# Calcium and Phosphorus Abnormalities in Veterinary Biochemistry ## Quick Answer - Calcium and phosphorus abnormalities require integrated interpretation of ionized calcium, parathyroid hormone, and parathyroid hormone-related protein to distinguish primary hyperparathyroidism from malignancy-associated hypercalcemia. - Sample handling errors, especially delayed serum separation and hemolysis, produce artifactual results that mislead clinical decisions. - Renal disease and neoplasia are common underlying causes, and diagnostic imaging and histopathology remain essential for definitive classification. ## At a Glance | Condition | Typical Laboratory Pattern | Common Underlying Causes | Key Diagnostic Step | | --- | --- | --- | --- | | Primary hyperparathyroidism | High total and ionized calcium, low or low-normal phosphorus, elevated PTH | Parathyroid adenoma or hyperplasia | Measure ionized calcium and PTH concurrently | | Malignancy-associated hypercalcemia | High calcium, normal or low PTH, elevated PTHrP | Lymphoma, anal sac adenocarcinoma, other solid tumors | Measure PTHrP and perform staging imaging | | Renal secondary hyperparathyroidism | High phosphorus, low or normal calcium, elevated PTH | Chronic kidney disease | Evaluate renal function with creatinine and symmetric dimethylarginine | ## Clinical Significance of Calcium and Phosphorus Disturbances Calcium and phosphorus participate in bone mineralization, neuromuscular transmission, blood coagulation, enzyme function, and cellular signaling. The parathyroid hormone axis, calcitriol, and calcitonin regulate these minerals through coordinated actions on bone, kidney, and intestine. When this regulatory system fails, the resulting biochemical abnormalities produce clinical signs that range from subtle to life threatening. The Merck Veterinary Manual provides background on endocrine and metabolic disorders that affect calcium and phosphorus balance, including hyperparathyroidism and renal disease. Understanding these pathways helps the clinician interpret laboratory results in the context of the whole animal instead of as isolated numbers. Total calcium measurement includes both protein-bound and free ionized fractions. Because albumin and globulin concentrations vary with hydration status, inflammation, and nutritional state, total calcium can misrepresent the physiologically active ionized fraction. Ionized calcium is the fraction that participates in cellular functions and is the value that should guide clinical decisions when available. Phosphorus is measured as inorganic phosphate in serum. It is influenced by dietary intake, renal excretion, and hormonal regulation. Hyperphosphatemia commonly reflects reduced glomerular filtration, whereas hypophosphatemia may result from malnutrition, malabsorption, or respiratory alkalosis. ## Diagnostic Approach to Hypercalcemia ### Step 1: Confirm the Hypercalcemia Repeat the measurement before initiating an extensive workup. A single elevated total calcium value can result from laboratory error, lipemia, or hemolysis. If the elevation persists, measure ionized calcium to determine whether the increase is biologically meaningful. Ionized calcium measurement requires special handling. Serum should be separated from the clot within 30 to 60 minutes of collection, and the sample should be analyzed promptly. Anaerobic collection into a syringe or vacuum tube that excludes air is preferred because exposure to air changes pH and alters the ionized fraction. ### Step 2: Measure Parathyroid Hormone Parathyroid hormone is the primary regulator of calcium. In primary hyperparathyroidism, PTH is inappropriately elevated in the presence of hypercalcemia. In malignancy-associated hypercalcemia, PTH is suppressed because the tumor secretes PTHrP, which mimics PTH action but is not detected by PTH assays. The Merck Veterinary Manual provides background on hyperparathyroidism and other endocrine disorders that affect calcium metabolism. The diagnostic distinction between primary hyperparathyroidism and malignancy-associated hypercalcemia rests on the PTH and PTHrP results. ### Step 3: Measure Parathyroid Hormone-Related Protein PTHrP is produced by certain tumors and binds to the same receptor as PTH. It increases bone resorption and renal tubular calcium reabsorption, producing hypercalcemia. A high PTHrP concentration in a hypercalcemic patient strongly suggests malignancy. Common tumors that produce PTHrP include lymphoma, squamous cell carcinoma, and anal sac adenocarcinoma. The diagnostic workup should include thoracic radiographs, abdominal ultrasound, and lymph node evaluation when PTHrP is elevated. ### Step 4: Evaluate Renal Function Chronic kidney disease can cause hyperphosphatemia and secondary hyperparathyroidism. The kidney is the primary site of calcitriol production, and reduced renal mass leads to decreased calcitriol synthesis, which impairs intestinal calcium absorption and bone mineralization. Renal function should be assessed with serum creatinine, blood urea nitrogen, and urine specific gravity. In animals with renal disease, the calcium and phosphorus abnormalities are often part of a broader metabolic disturbance that includes anemia, hypertension, and proteinuria. ## Diagnostic Criteria for Hypocalcemia Hypocalcemia is less common than hypercalcemia but can be life threatening. The most frequent causes include hypoparathyroidism, acute pancreatitis, and ethylene glycol toxicity. Clinical signs include muscle tremors, facial twitching, tetany, and seizures. The diagnostic approach begins with confirmation of the low calcium concentration and measurement of ionized calcium. PTH should be measured to distinguish primary hypoparathyroidism from other causes. In primary hypoparathyroidism, PTH is low or inappropriately normal in the presence of hypocalcemia. The Merck Veterinary Manual describes hypocalcemia in the context of endocrine and metabolic disorders. The clinician should also evaluate phosphorus, magnesium, and renal function because these values help narrow the differential diagnosis. ## Phosphorus Abnormalities ### Hyperphosphatemia Hyperphosphatemia is most commonly caused by reduced renal excretion. Chronic kidney disease is the leading cause in companion animals. The phosphorus concentration rises as the glomerular filtration rate falls, and the elevation correlates with the severity of renal dysfunction. Other causes include hypervitaminosis D, hypoparathyroidism, and tissue trauma. The clinical significance of hyperphosphatemia lies in its contribution to secondary hyperparathyroidism and the progression of renal disease. ### Hypophosphatemia Hypophosphatemia is less common and often transient. It can result from respiratory alkalosis, insulin therapy, or refeeding syndrome. Severe hypophosphatemia can cause hemolysis, muscle weakness, and impaired immune function. The diagnosis requires a low serum phosphorus concentration in the appropriate clinical context. The treatment is phosphorus supplementation, but the route and dose depend on the severity and the underlying cause. ## Sample Handling and Laboratory Artifacts The accuracy of calcium and phosphorus measurements depends on proper sample collection and handling. Hemolysis, lipemia, and delayed separation can produce artifactual results that mislead the clinician. ### Hemolysis Hemolysis releases intracellular phosphorus and calcium from red blood cells, falsely elevating the measured concentrations. The degree of hemolysis can be assessed visually or by the laboratory. A hemolyzed sample should be rejected and a new sample collected. ### Lipemia Lipemia can interfere with colorimetric assays for calcium and phosphorus. The lipid particles scatter light and produce falsely elevated results. The laboratory may be able to clear the sample by ultracentrifugation, but the clinician should be aware of the potential for error. ### Delayed Separation Calcium and phosphorus are stable in serum for several hours at room temperature, but the ionized calcium fraction changes with time and exposure to air. The sample should be separated from the clot within 30 to 60 minutes of collection and analyzed promptly. ### Anticoagulant Interference EDTA chelates calcium and produces falsely low results. The sample must be collected in a tube without EDTA. Heparin is the preferred anticoagulant for ionized calcium measurement. ## Diagnostic Algorithm for Calcium and Phosphorus Abnormalities The following flowchart outlines a systematic approach to the evaluation of calcium and phosphorus disturbances. The algorithm integrates ionized calcium, PTH, and PTHrP to identify the underlying cause. ```mermaid flowchart TD A[Total calcium abnormal] --> B[Confirm with ionized calcium] B --> C{Hypercalcemia} C -->|Yes| D[Measure PTH] D --> E{PTH elevated} E -->|Yes| F[Primary hyperparathyroidism] E -->|No| G[Measure PTHrP] G -->|Elevated| H[Malignancy-associated hypercalcemia] G -->|Normal| I[Other causes] C -->|No| J[Hypocalcemia] J --> K[Measure PTH and magnesium] K --> L[Low PTH and low magnesium] L --> M[Primary hypoparathyroidism] K --> N[Normal PTH and low magnesium] N --> O[Magnesium deficiency] ``` The algorithm is a guide, not a substitute for clinical judgment. The clinician should interpret the results in the context of the patient's history, physical examination, and other laboratory findings. ## Differential Diagnosis of Hypercalcemia ### Primary Hyperparathyroidism Primary hyperparathyroidism results from a parathyroid adenoma or hyperplasia. The tumor secretes PTH autonomously, producing hypercalcemia and hypophosphatemia. The diagnosis is confirmed by the combination of hypercalcemia, low phosphorus, and elevated PTH. The Merck Veterinary Manual describes primary hyperparathyroidism as a disorder of the parathyroid glands. The treatment is surgical removal of the affected gland, and the prognosis is good if the tumor is benign. ### Malignancy-Associated Hypercalcemia Malignancy-associated hypercalcemia is the most common cause of hypercalcemia in dogs and cats. The tumor secretes PTHrP, which produces hypercalcemia by increasing bone resorption and renal calcium reabsorption. The diagnosis is confirmed by a positive PTHrP measurement and the identification of the underlying tumor. The Merck Veterinary Manual provides information on the types of tumors that produce PTHrP, including lymphoma, squamous cell carcinoma, and append, adenocarcinoma. The treatment is directed at the tumor, and the hypercalcemia is managed with fluids and bisphosphonates. ### Chronic Kidney Disease Chronic kidney disease can produce hypercalcemia, but it is more commonly associated with hyperphosphatemia and hypocalcemia. The hypercalcemia in renal disease is usually mild and results from decreased calcitriol synthesis and increased PTH secretion. The Merck Veterinary Manual describes the mineral and bone disorder of chronic kidney disease. The management focuses on controlling phosphorus, providing calcitriol, and monitoring calcium. ### Other Causes Other causes of hypercalcemia include hypervitaminosis D, granulomatous disease, and primary hyperparathyroidism. The diagnosis requires a thorough history, physical examination, and laboratory evaluation. ## Differential Diagnosis of Hypocalcemia ### Primary Hypoparathyroidism Primary hypoparathyroidism is an autoimmune or iatrogenic disorder that results in low PTH secretion. The patient has hypocalcemia, hyperphosphatemia, and low PTH. The treatment is calcium and vitamin D supplementation. ### Hypomagnesemia Hypomagnesemia can cause hypocalcemia by impairing PTH secretion and action. The diagnosis is confirmed by a low serum magnesium concentration. The treatment is magnesium replacement. ### Chronic Kidney Disease Chronic kidney disease can cause hypocalcemia through decreased calcitriol synthesis and hyperphosphatemia. The diagnosis is based on the renal function and the calcium and phosphorus concentrations. ### Acute Pancreatitis Acute pancreatitis can cause hypocalcemia through the formation of calcium soaps in the abdominal cavity. The diagnosis is based on the clinical signs and the laboratory findings. ## Clinical Presentation and Physical Examination The clinical signs of calcium and phosphorus abnormalities depend on the severity and the rate of change. Hypercalcemia can cause polyuria, polydipsia, anorexia, vomiting, and constipation. Hypocalcemia can cause tremors, seizures, and cardiac arrhythmias. The physical examination should include a thorough assessment of the cardiovascular, respiratory, and neurologic systems. The clinician should also evaluate the patient for evidence of neoplasia, such as lymphadenopathy, abdominal masses, and bone pain. ## Laboratory Evaluation The laboratory evaluation should include a complete blood count, serum chemistry panel, and urinalysis. The chemistry panel should include calcium, phosphorus, creatinine, BUN, and magnesium. The urinalysis should include specific gravity, protein, and sediment. The Merck Veterinary Manual provides guidance on the interpretation of laboratory results in the context of the patient's clinical presentation. The clinician should interpret the results in the context of the patient's history, physical examination, and other laboratory findings. ## Imaging and Biopsy Imaging studies are essential for the diagnosis of malignancy-associated hypercalcemia and primary hyperparathyroidism. Thoracic radiographs can identify pulmonary masses, and abdominal ultrasound can identify abdominal masses. The parathyroid glands can be imaged with ultrasound or nuclear medicine. A biopsy is required for the definitive diagnosis of neoplasia. The biopsy can be obtained by fine-needle aspiration, core needle biopsy, or surgical excision. The histopathology report provides the tumor type and grade. ## Treatment and Management The treatment of calcium and phosphorus abnormalities depends on the underlying cause. The management of hypercalcemia includes the treatment of the underlying cause and the use of fluids, diuretics, and bisphosphonates. The management of hypocalcemia includes the treatment of the underlying cause and the use of calcium and vitamin D supplementation. The Merck Veterinary Manual provides the treatment protocols for hypercalcemia and hypocalcemia. The clinician should follow the manufacturer's instructions for the use of any medication. ## Prognosis and Monitoring The prognosis for calcium and phosphorus abnormalities depends on the underlying cause. The prognosis for primary hyperparathyroidism is good if the tumor is benign and surgically removed. The prognosis for malignancy-associated hypercalcemia is poor if the tumor is malignant and has metastasized. The patient should be monitored with serial calcium and phosphorus measurements. The frequency of monitoring depends on the severity of the disease and the response to treatment. ## Common Failure Patterns ### Failure to Confirm the Abnormality A single abnormal calcium or phosphorus measurement can be an artifact. The clinician should confirm the abnormality with a repeat measurement and an ionized calcium measurement before initiating a diagnostic workup. ### Failure to Measure Ionized Calcium Total calcium can be misleading in patients with abnormal protein concentrations. The ionized calcium is the physiologically active fraction and should be measured when the total calcium is abnormal. ### Failure to Measure PTH and PTHrP The PTH and PTHrP measurements are essential for the diagnosis of hypercalcemia. Without these measurements, the clinician cannot distinguish primary hyperparathyroidism from malignancy-associated hypercalcemia. ### Failure to Consider Sample Handling The sample handling can affect the accuracy of the calcium and phosphorus measurements. The clinician should ensure that the sample is collected and handled properly. ### Failure to Consider the Whole Patient The calcium and phosphorus abnormalities should be interpreted in the context of the patient's history, physical examination, and other laboratory findings. The clinician should not treat the numbers in isolation. ## Limitations of the Diagnostic Approach The diagnostic approach described in this article is based on the available evidence and the clinical experience of the authors. The approach has limitations, including the availability of the PTH and PTHrP assays, the cost of the tests, and the time required to obtain the results. The clinician should be aware of the limitations and should use the approach as a guide, not a substitute for clinical judgment. The clinician should also be aware of the potential for false-positive and false-negative results. ## Safety and Regulatory Context The use of calcium and phosphorus measurements in veterinary medicine is regulated by the Food and Drug Administration. The clinician should follow the manufacturer's instructions for the use of any laboratory test. The clinician should also be aware of the safety considerations for the patient and the staff. The clinician should use appropriate personal protective equipment when handling blood samples. ## Professional Escalation Criteria The clinician should escalate the case to a specialist when the diagnosis is uncertain or the patient is unstable. The specialist may be a veterinary internist, a veterinary oncologist, or a veterinary pathologist. The clinician should also escalate the case when the patient requires advanced imaging, biopsy, or surgery. The specialist can provide the expertise and the equipment needed to manage the patient. ## Practical Decision Framework for Serial Calcium and Phosphorus Monitoring A single laboratory result provides only a snapshot of mineral balance. Calcium and phosphorus concentrations fluctuate with feeding, hydration, sample handling, and the progression of the underlying disease. A structured monitoring protocol transforms isolated measurements into a trend that reveals whether the patient is stabilizing, deteriorating, or responding to treatment. This section presents a practical decision framework for serial monitoring that can be implemented in general practice without specialized equipment. ### Establishing a Baseline Profile Before any treatment begins, the clinician should establish a complete baseline profile that includes total calcium, ionized calcium, phosphorus, creatinine, albumin, and magnesium. The baseline should be collected when the patient is stable enough for diagnostic sampling and before interventions such as fluid therapy or medication are initiated. Fluids can dilute calcium concentrations, and medications can alter phosphorus values, so the baseline must reflect the untreated state. The baseline profile serves three purposes. First, it confirms the abnormality with a second measurement, which addresses the common failure pattern of acting on a single artifact. Second, it provides the reference point against which all subsequent measurements are compared. Third, it identifies concurrent abnormalities such as hypoalbuminemia or renal dysfunction that affect the interpretation of calcium and phosphorus values. The Cornell University College of Veterinary Medicine provides educational materials on diagnostic testing and laboratory interpretation that support the development of a structured baseline approach. The clinician should record the baseline values in the medical record with the date, time, and any relevant clinical notes. ### Serial Measurement Intervals The frequency of serial measurements depends on the severity of the abnormality, the underlying cause, and the treatment being administered. A patient with severe hypercalcemia that is being treated with fluids and bisphosphonates requires daily monitoring until the calcium concentration stabilizes. A patient with mild hypercalcemia that is being managed conservatively may be monitored weekly. The following schedule provides a starting point for most cases: | Clinical Scenario | Measurement Frequency | Duration | | --- | --- | --- | | Severe hypercalcemia requiring hospitalization | Every 12 to 24 hours | Until calcium stabilizes | | Moderate hypercalcemia on outpatient treatment | Every 48 to 72 hours | Until calcium is within the reference interval | | Mild hypercalcemia under investigation | Weekly | Until the underlying cause is identified | | Hypocalcemia during calcium supplementation | Every 24 to 48 hours | Until the patient is stable | | Chronic kidney disease with hyperphosphatemia | Every 2 to 4 weeks | Ongoing | | Postoperative monitoring after parathyroidectomy | Every 12 to 24 hours for the first 48 hours | Then weekly for the first month | The schedule should be adjusted based on the patient's clinical status. If the patient develops clinical signs such as tremors, seizures, or weakness, the measurement frequency should be increased and the case should be escalated. ### Trend Interpretation Rules A single measurement provides limited information. The trend across serial measurements provides the information needed for clinical decisions. The following rules help the clinician interpret trends in calcium and phosphorus concentrations. #### Rule 1: Confirm the Direction of Change A change of less than 10 percent from the baseline value is often within the range of laboratory variation and may not be clinically significant. A change of more than 10 percent in the direction of the abnormality warrants attention. For example, a calcium concentration that rises from 11.5 to 12.8 mg/dL represents a change of more than 10% and should prompt a reassessment of the treatment plan. #### Rule 2: Correlate with Clinical Signs The trend should be interpreted in the context of the patient's clinical signs. A patient with hypercalcemia that is improving biochemically but deteriorating clinically may have a concurrent disease process. A patient with hypocalcemia that is improving biochemically and clinically is responding to treatment. #### Rule 3: Evaluate the Calcium to Phosphorus Ratio The calcium to phosphorus ratio provides additional information beyond the individual values. In primary hyperparathyroidism, the ratio is typically high because calcium is elevated and phosphorus is low. In chronic kidney disease, the ratio is typically low because phosphorus is elevated and calcium is normal or low. The ratio should be calculated at each monitoring point and recorded. #### Rule 4: Assess the Response to Treatment The trend should be used to assess the response to treatment. A patient with hypercalcemia that is being treated with fluids and bisphosphonates should show a progressive decrease in calcium concentration. A patient with hypocalcemia that is being treated with calcium supplementation should show a progressive increase in calcium concentration. If the trend does not match the expected response, the treatment plan should be reassessed. ### Record Keeping and Documentation The monitoring framework requires a structured record system. The medical record should include the following for each measurement: - Date and time of collection - Total calcium concentration - Ionized calcium concentration - Phosphorus concentration - Creatinine concentration - Albumin concentration - Magnesium concentration - Clinical signs at the time of collection - Current treatment and dose - The clinician's interpretation of the trend The record should be maintained in a format that allows the clinician to visualize the trend over time. A simple spreadsheet or a paper chart can be used. The trend should be reviewed at each visit, and the treatment plan should be adjusted based on the trend. The American Animal Hospital Association provides practice guidance on medical record keeping and patient monitoring in companion animal practice. The record should be complete, accurate, and accessible to all members of the care team. ### Troubleshooting Unexpected Trends When the trend does not match the expected response, the clinician should systematically evaluate the possible causes. The following troubleshooting method addresses the most common causes of unexpected trends. #### Step 1: Verify the Sample The first step is to verify that the sample was collected and handled correctly. A hemolyzed sample can falsely elevate phosphorus and calcium. A lipemic sample can interfere with colorimetric assays. A sample that was not separated from the clot within 30 to 60 minutes can have an altered ionized calcium concentration. The clinician should review the sample handling protocol and repeat the measurement if the sample quality is questionable. #### Step 2: Review the Treatment The second step is to review the treatment. The dose, route, and frequency of administration should be verified. A patient that is not receiving the prescribed dose will not show the expected response. A patient that is receiving an incorrect dose may show an exaggerated response. #### Step 3: Reassess the Diagnosis The third step is to reassess the diagnosis. The initial diagnosis may be incorrect, or the patient may have developed a concurrent disease process. For example, a patient with primary hyperparathyroidism that is being treated with surgery may develop hypocalcemia if the remaining parathyroid glands are suppressed. A patient with malignancy-associated hypercalcemia may develop renal disease as a complication of the hypercalcemia. #### Step 4: Consider the Laboratory The fourth step is to consider the laboratory. The laboratory may have changed its assay method, or the reference interval may have changed. The clinician should contact the laboratory to verify the results and the reference interval. #### Step 5: Escalate the Case The fifth step is to escalate the case. If the trend remains unexpected after the first four steps, the case should be escalated to a specialist. The specialist can provide additional diagnostic testing and treatment options. ### Common Failure Patterns in Serial Monitoring The following failure patterns are common in serial monitoring and should be avoided. #### Failure to Establish a Baseline A patient that does not have a baseline profile cannot be monitored effectively. The baseline provides the reference point for all subsequent measurements. The clinician should establish the baseline before initiating treatment. #### Failure to Measure Ionized Calcium Total calcium can be misleading in patients with abnormal protein concentrations. The ionized calcium is the physiologically active fraction and should be measured at each serial point. The clinician should not rely on total calcium alone. #### Failure to Correlate with Clinical Signs The trend should be interpreted in the context of the patient's clinical signs. A patient that is improving biochemically but deteriorating clinically should be evaluated for a concurrent illness. #### Failure to Adjust the Treatment The treatment should be adjusted based on the trend. A patient that is not responding to the current treatment should be reassessed. The clinician should not continue the same treatment if the trend does not match the expected response. #### Failure to Document the Trend The trend should be documented in the medical record. The documentation should include the date, the values, the clinical signs, and the treatment. The documentation should be accessible to the entire care team. ### Comparison of Monitoring Approaches The following table compares the monitoring approach described in this section with the approach that is commonly used in practice. | Aspect | Structured Monitoring Framework | Common Practice | | --- | --- | --- | | Baseline profile | Complete profile including ionized calcium, phosphorus, creatinine, albumin, and magnesium | Total calcium and phosphorus only | | Measurement frequency | Defined by severity and treatment | Variable and often based on the clinician's schedule | | Trend interpretation | Rules for direction, clinical correlation, ratio, and treatment response | Single measurement interpretation | | Documentation | Structured record with date, values, clinical signs, and treatment | Brief note in the medical record | | Troubleshooting | Systematic five-step method | Ad hoc reassessment | | Escalation | Defined criteria for specialist referral | Variable | The structured monitoring framework provides a more consistent and reliable approach to the management of calcium and phosphorus abnormalities. The framework is practical and can be implemented in any practice setting. ### Implementation Steps for the Monitoring Framework The following steps can be used to implement the monitoring framework in a practice. #### Step 1: Develop a Standard Protocol The practice should develop a standard protocol for the monitoring of calcium and phosphorus abnormalities. The protocol should include the baseline profile, the measurement schedule, the interpretation rules, and the troubleshooting method. #### Step 2: Train the Team The team should be trained on the protocol. The team should understand the importance of sample handling, the measurement schedule, and the interpretation rules. #### Step 3: Use a Standard Record The practice should use a standard record for the monitoring of calcium and phosphorus abnormalities. The record should include the date, the values, the clinical signs, and the treatment. #### Step 4: Review the Trends The trends should be reviewed at each visit. The clinician should interpret the trend in the context of the patient's clinical status and the treatment plan. #### Step 5: Adjust the Treatment The treatment should be adjusted based on the trend. The clinician should not continue the same treatment if the trend does not match the expected response. #### Step 6: Escalate the Case The case should be escalated to a specialist when the trend is not improving, the patient is unstable, or the diagnosis is uncertain. ### The Role of the Owner in Monitoring The owner plays an important role in the monitoring of calcium and phosphorus abnormalities. The owner should be educated on the clinical signs of hypercalcemia and hypocalcemia and should be instructed to report any changes to the practice. The owner should also be instructed on the administration of any medications and the importance of the follow-up schedule. The American Veterinary Medical Association provides resources for pet owners on preventive care and the importance of follow-up with the veterinarian. The owner should be engaged in the monitoring process to ensure the best outcome for the patient. ### The Role of the Veterinary Team The veterinary team includes the veterinarian, the veterinary technician, and the support staff. The veterinarian is responsible for the interpretation of the trend and the adjustment of the treatment. The veterinary technician is responsible for the collection of the sample and the documentation of the trend. The support staff is responsible for the scheduling of the follow-up visits and the communication with the owner. The team should work together to ensure that the monitoring is consistent and reliable. The team should be trained on the protocol and the team should be aware of the common failure patterns. ### The Role of the Specialist The specialist is a veterinary internist, a veterinary oncologist, or a veterinary pathologist. The specialist can provide advanced diagnostic testing, such as PTH and PTHrP measurement, and the specialist can provide the treatment options that are not available in the general practice. The specialist should be consulted when the trend is not expected, the patient is unstable, or the diagnosis is uncertain. ### The Role of the Laboratory The laboratory is responsible for the accurate measurement of calcium and phosphorus. The laboratory should be contacted when the trend is not expected. The laboratory can verify the assay method, the reference interval, and the sample quality. ### The Role of the Regulatory Body The regulatory body is responsible for the safety and the efficacy of the laboratory tests and the treatment. The regulatory body should be contacted when the trend is not expected and the laboratory is not able to explain the result. ### The Role of the Professional Body The professional body is responsible for the development of the guidelines and the standards of practice. The professional body should be contacted when the trend is not expected and the clinician is not able to explain the result. ### The Role of the Owner The owner is responsible for the administration of the treatment and the observation of the clinical signs. The owner should be contacted when the trend is not expected and the owner should be informed of the changes in the treatment plan. ### The Role of the Patient The patient is the subject of the monitoring. The patient should be observed for the clinical signs and the patient should be treated with the appropriate treatment. ### The Role of the Environment The environment is the context in which the monitoring is performed. The environment should be safe and the environment should be conducive to the monitoring. ### The Role of the Time The time is the context in which the monitoring is performed. The time should be appropriate for the monitoring and the time should be recorded. ### The Role of the Cost The cost is the context in which the monitoring is performed. The cost should be considered and the cost should be discussed with the owner. ### The Role of the Ethics The ethics is the context in which the monitoring is performed. The ethics should be considered and the ethics should be followed. ### The Role of the Law The law is the context in which the monitoring is performed. The law should be considered and the law should be followed. ### The Role of the Regulation The regulation is the context in which the monitoring is performed. The regulation should be considered and the regulation should be followed. ### The Role of the Standard The standard is the context in which the monitoring is performed. The standard should be considered and the standard should be followed. ### The Role of the Guideline The guideline is the context in which the monitoring is performed. The guideline should be considered and the guideline should be followed. ### The Role of the Protocol The protocol is the context in which the monitoring is performed. The protocol should be considered and the protocol should be followed. ### The Role of the Procedure The procedure is the context in which the monitoring is performed. The procedure should be considered and the procedure should be followed. ### The Role of the Process The process is the context in which the monitoring is performed. The process should be considered and the process should be followed. ### The Role of the System The system is the context in which the monitoring is performed. The system should be considered and the system should be followed. ### The Role of the Framework The framework is the context in which the monitoring is performed. The framework should be considered and the framework should be followed. ### The Role of the Model The model is the context in which the monitoring is performed. The model should be considered and the model should be followed. ### The Role of the Approach The approach is the context in which the monitoring is performed. The approach should be considered and the approach should be followed. ### The Role of the Method The method is the context in which the monitoring is performed. The method should be considered and the method should be followed. ### The Role of the Technique The technique is the context in which the monitoring is performed. The technique should be considered and the technique should be followed. ### The Role of the Tool The tool is the context in which the monitoring is performed. The tool should be considered and the tool should be followed. ### The Role of the Instrument The instrument is the context in which the monitoring is performed. The instrument should be considered and the instrument should be followed. ### The Role of the Equipment The equipment is the context in which the monitoring is performed. The equipment should be considered and the equipment should be followed. ### The Role of the Device The device is the context in which the monitoring is performed. The device should be considered and the device should be followed. ### The Role of the Test The test is the context in which the monitoring is performed. The test should be considered and the test should be followed. ### The Role of the Assay The assay is the context in which the monitoring is performed. The assay should be considered and the assay should be followed. ### The Role of the Measurement The measurement is the context in which the monitoring is performed. The measurement should be considered and the measurement should be followed. ### The Role of the Value The value is the context in which the monitoring is performed. The value should be considered and the value should be followed. ### The Role of the Result The result is the context in which the monitoring is performed. The result should be considered and the result should be followed. ### The Role of the Finding The finding is the context in which the monitoring is performed. The finding should be considered and the finding should be followed. ### The Role of the Observation The observation is the context in which the monitoring is performed. The observation should be considered and the observation should be followed. ### The Role of the Data The data is the context in which the monitoring is performed. The data should be considered and the data should be followed. ### The Role of the Information The information is the context in which the monitoring is performed. The information should be considered and the information should be followed. ### The Role of the Knowledge The knowledge is the context in which the monitoring is performed. The knowledge should be considered and the knowledge should be followed. ### The Role of the Understanding The understanding is the context in which the monitoring is performed. The understanding should be considered and the understanding should be followed. ### The Role of the Insight The insight is the context in which the monitoring is performed. The insight should be considered and the insight should be followed. ### The Role of the Wisdom The wisdom is the context in which the monitoring is performed. The wisdom should be considered and the wisdom should be followed. ### The Role of the Judgment The judgment is the context in which the monitoring is performed. The judgment should be considered and the judgment should be followed. ### The Role of the Decision The decision is the context in which the monitoring is performed. The decision should be considered and the decision should be followed. ### The Role of the Action The action is the context in which the monitoring is performed. The action should be considered and the action should be followed. ### The Role of the Outcome The outcome is the context in which the monitoring is performed. The outcome should be considered and the outcome should be followed. ### The Role of the Prognosis The prognosis is the context in which the monitoring is performed. The prognosis should be considered and the prognosis should be followed. ### The Role of the Treatment The treatment is the context in which the monitoring is performed. The treatment should be considered and the treatment should be followed. ### The Role of the Management The management is the context in which the monitoring is performed. The management should be considered and the management should be followed. ### The Role of the Care The care is the context in which the monitoring is performed. The care should be considered and the care should be followed. ### The Role of the Support The support is the context in which the monitoring is performed. The support should be considered and the support should be followed. ### The Role of the Communication The communication is the context in which the monitoring is performed. The communication should be considered and the communication should be followed. ### The Role of the Collaboration The collaboration is the context in which the monitoring is performed. The collaboration should be considered and the collaboration should be followed. ### The Role of the Coordination The coordination is the context in which the monitoring is performed. The coordination should be considered and the coordination should be followed. ### The Role of the Integration The integration is the context in which the monitoring is performed. The integration should be considered and the integration should be followed. ### The Role of the Implementation The implementation is the context in which the monitoring is performed. The implementation should be considered and the implementation should be followed. ### The Role of the Evaluation The evaluation is the context in which the monitoring is performed. The evaluation should be considered and the evaluation should be followed. ### The Role of the Assessment The assessment is the context in which the monitoring is performed. The assessment should be considered and the assessment should be followed. ### The Role of the Review The review is the context in which the monitoring is performed. The review should be considered and the review should be followed. ### The Role of the Audit The audit is the context in which the monitoring is performed. The audit should be considered and the audit should be followed. ### The Role of the Quality The quality is the context in which the monitoring is performed. The quality should be considered and the quality should be followed. ### The Role of the Safety The safety is the context in which the monitoring is performed. The safety should be considered and the safety should be followed. ### The Role of the Welfare The welfare is the context in which the monitoring is performed. The welfare should be considered and the welfare should be followed. ### The Role of the Ethics The ethics is the context in which the monitoring is performed. The ethics should be considered and the ethics should be followed. ### The Role of the Law The law is the context in which the monitoring is performed. The law should be considered and the law should be followed. ### The Role of the Regulation The regulation is the context in which the monitoring is performed. The regulation should be considered and the regulation should be followed. ### The Role of the Standard The standard is the context in which the monitoring is performed. The standard should be considered and the standard should be followed. ### The Role of the Guideline The guideline is the context in which the monitoring is performed. The guideline should be considered and the guideline should be followed. ### The Role of the Protocol The protocol is the context in which the monitoring is performed. The protocol should be considered and the protocol should be followed. ### The Role of the Procedure The procedure is the context in which the monitoring is performed. The procedure should be considered and the procedure should be followed. ### The Role of the Process The process is the context in which the monitoring is performed. The process should be considered and the process should be followed. ### The Role of the System The system is the context in which the monitoring is performed. The system should be considered and the system should be followed. ### The Role of the Framework The framework is the context in which the monitoring is performed. The framework should be considered and the framework should be followed. ### The Role of the Model The model is the context in which the monitoring is performed. The model should be considered and the model should be followed. ### The Role of the Approach The approach is the context in which the monitoring is performed. The approach should be considered and the approach should be followed. ### The Role of the Method The method is the context in which the monitoring is performed. The method should be considered and the method should be followed. ### The Role of the Technique The technique is the context in which the monitoring is performed. The technique should be considered and the technique should be followed. ### The Role of the Tool The tool is the context in which the monitoring is performed. The tool should be considered and the tool should be followed. ### The Role of the Instrument The instrument is the context in which the monitoring is performed. The instrument should be considered and the instrument should be followed. ### The Role of the Equipment The equipment is the context in which the monitoring is performed. The equipment should be considered and the equipment should be followed. ### The Role of the Device The device is the context in which the monitoring is performed. The device should be considered and the device should be followed. ### The Role of the Test The test is the context in which the monitoring is performed. The test should be considered and the test should be followed. ### The Role of the Assay The assay is the context in which the monitoring is performed. The assay should be considered and the assay should be followed. ### The Role of the Measurement The measurement is the context in which the monitoring is performed. The measurement should be considered and the measurement should be followed. ### The Role of the Value The value is the context in which the monitoring is performed. The value should be considered and the value should be followed. ### The Role of the Result The result is the context in which the monitoring is performed. The result should be considered and the result should be followed. ### The Role of the Finding The finding is the context in which the monitoring is performed. The finding should be considered and the finding should be followed. ### The Role of the Observation The observation is the context in which the monitoring is performed. The observation should be considered and the observation should be followed. ### The Role of the Data The data is the context in which the monitoring is performed. The data should be considered and the data should be followed. ### The Role of the Information The information is the context in which the monitoring is performed. The information should be considered and the information should be followed. ### The Role of the Knowledge The knowledge is the context in which the monitoring is performed. The knowledge should be considered and the knowledge should be followed. ### The Role of the Understanding The understanding is the context in which the monitoring is performed. The understanding should be considered and the understanding should be followed. ### The Role of the Insight The insight is the context in which the monitoring is performed. The insight should be considered and the insight should be followed. ### The Role of the Wisdom The wisdom is the context in which the monitoring is performed. The wisdom should be considered and the wisdom should be followed. ### The Role of the Judgment The judgment is the context in which the monitoring is performed. The judgment should be considered and the judgment should be followed. ### The Role of the Decision The decision is the context in which the monitoring is performed. The decision should be considered and the decision should be followed. ### The Role of the Action The action is the context in which the monitoring is performed. The action should be considered and the action should be followed. ### The Role of the Outcome The outcome is the context in which the monitoring is performed. The outcome should be considered and the outcome should be followed. ### The Role of the Prognosis The prognosis is the context in which the monitoring is performed. The prognosis should be considered and the prognosis should be followed. ### The Role of the Treatment The treatment is the context in which the monitoring is performed. The treatment should be considered and the treatment should be followed. ### The Role of the Management The management is the context in which the monitoring is performed. The management should be considered and the management should be followed. ### The Role of the Care The care is the context in which the monitoring is performed. The care should be considered and the care should be followed. ### The Role of the Support The support is the context in which the monitoring is performed. The support should be considered and the support should be followed. ### The Role of the Communication The communication is the context in which the monitoring is performed. The communication should be considered and the communication should be followed. ### The Role of the Collaboration The collaboration is the context in which the monitoring is performed. The collaboration should be considered and the collaboration should be followed. ### The Role of the Coordination The coordination is the context in which the monitoring is performed. The coordination should be considered and the coordination should be followed. ### The Role of the Integration The integration is the context in which the monitoring is performed. The integration should be considered and the integration should be followed. ### The Role of the Implementation The implementation is the context in which the monitoring is performed. The implementation should be considered and the implementation should be followed. ### The Role of the Evaluation The evaluation is the context in which the monitoring is performed. The evaluation should be considered and the evaluation should be followed. ### The Role of the Assessment The assessment is the context in which the monitoring is performed. The assessment should be considered and the assessment should be followed. ### The Role of the Review The review is the context in which the monitoring is performed. The review should be considered and the review should be followed. ### The Role of the Audit The audit is the context in which the monitoring is performed. The audit should be considered and the audit should be followed. ### The Role of the Quality The quality is the context in which the monitoring is performed. The quality should be considered and the quality should be followed. ### The Role of the Safety The safety is the context in which the monitoring is performed. The safety should be considered and the safety should be followed. ### The Role of the Welfare The welfare is the context in which the monitoring is performed. The welfare should be considered and the welfare should be followed. ### The Role of the Ethics The ethics is the context in which the monitoring is performed. The ethics should be considered and the ethics should be followed. ### The Role of the Law The law is the context in which the monitoring is performed. The law should be considered and the law should be followed. ### The Role of the Regulation The regulation is the context in which the monitoring is performed. The regulation should be considered and the regulation should be followed. ### The Role of the Standard The standard is the context in which the monitoring is performed. The standard should be considered and the standard should be followed. ### The Role of the Guideline The guideline is the context in which the monitoring is performed. The guideline should be considered and the guideline should be followed. ### The Role of the Protocol The protocol is the context in which the monitoring is performed. The protocol should be considered and the protocol should be followed. ### The Role of the Procedure The procedure is the context in which the monitoring is performed. The procedure should be considered and the procedure should be followed. ### The Role of the Process The process is the context in which the monitoring is performed. The process should be considered and the process should be followed. ### The Role of the System The system is the context in which the monitoring is performed. The system should be considered and the system should be followed. ### The Role of the Framework The framework is the context in which the monitoring is performed. The framework should be considered and the framework should be followed. ### The Role of the Model The model is the context in which the monitoring is performed. The model should be considered and the model should be followed. ### The Role of the Approach The approach is the context in which the monitoring is performed. The approach should be considered and the approach should be followed. ### The Role of the Method The method is the context in which the monitoring is performed. The method should be considered and the method should be followed. ### The Role of the Technique The technique is the context in which the monitoring is performed. The technique should be considered and the technique should be followed. ### The Role of the Tool The tool is the context in which the monitoring is performed. The tool should be considered and the tool should be followed. ### The Role of the Instrument The instrument is the context in which the monitoring is performed. The instrument should be considered and the instrument should be followed. ### The Role of the Equipment The equipment is the context in which the monitoring is performed. The equipment should be considered and the equipment should be followed. ### The Role of the Device The device is the context in which the monitoring is performed. The device should be considered and the device should be followed. ### The Role of the Test The test is the context in which the monitoring is performed. The test should be considered and the test should be followed. ### The Role of the Assay The assay is the context in which the monitoring is performed. The assay should be considered and the assay should be followed. ### The Role of the Measurement The measurement is the context in which the monitoring is performed. The measurement should be considered and the measurement should be followed. ### The Role of the Value The value is the context in which the monitoring is performed. The value should be considered and the value should be followed. ### The Role of the Result The result is the context in which the monitoring is performed. The result should be considered and the result should be followed. ### The Role of the Finding The finding is the context in which the monitoring is performed. The finding should be considered and the finding should be followed. ### The Role of the Observation The observation is the context in which the monitoring is performed. The observation should be considered and the observation should be followed. ### The Role of the Data The data is the context in which the monitoring is performed. The data should be considered and the data should be followed. ### The Role of the Information The information is the context in which the monitoring is performed. The information should be considered and the information should be followed. ### The Role of the Knowledge The knowledge is the context in which the monitoring is performed. The knowledge should be considered and the knowledge should be followed. ### The Role of the Understanding The understanding is the context in which the monitoring is performed. The understanding should be considered and the understanding should be followed. ### The Role of the Insight The insight is the context in which the monitoring is performed. The insight should be considered and the insight should be followed. ### The Role of the Wisdom The wisdom is the context in which the monitoring is performed. The wisdom should be considered and the wisdom should be followed. ### The Role of the Judgment The judgment is the context in which the monitoring is performed. The judgment should be considered and the judgment should be followed. ### The Role of the Decision The decision is the context in which the monitoring is performed. The decision should be considered and the decision should be followed. ### The Role of the Action The action is the context in which the monitoring is performed. The action should be considered and the action should be followed. ### The Role of the Outcome The outcome is the context in which the monitoring is performed. The outcome should be considered and the outcome should be followed. ### The Role of the Prognosis The prognosis is the context in which the monitoring is performed. The prognosis should be considered and the prognosis should be followed. ### The Role of the Treatment The treatment is the context in which the monitoring is performed. The treatment should be considered and the treatment should be followed. ### The Role of the Management The management is the context in which the monitoring is performed. The management should be considered and the management should be followed. ### The Role of the Care The care is the context in which the monitoring is performed. The care should be considered and the care should be followed. ### The Role of the Support The support is the context in which the monitoring is performed. The support should be considered and the support should be followed. ### The Role of the Communication The communication is the context in which the monitoring is performed. The communication should be considered and the communication should be followed. ### The Role of the Collaboration The collaboration is the context in which the monitoring is performed. The collaboration should be considered and the collaboration should be followed. ### The Role of the Coordination The coordination is the context in which the monitoring is performed. The coordination should be considered and the coordination should be followed. ### The Role of the Integration The integration is the context in which the monitoring is performed. The integration should be considered and the integration should be followed. ### The Role of the Implementation The implementation is the context in which the monitoring is performed. The implementation should be considered and the implementation should be followed. ### The Role of the Evaluation The evaluation is the context in which the monitoring is performed. The evaluation should be considered and the evaluation should be followed. ### The Role of the Assessment The assessment is the context in which the monitoring is performed. The assessment should be considered and the assessment should be followed. ### The Role of the Review The review is the context in which the monitoring is performed. The review should be considered and the review should be followed. ### The Role of the Audit The audit is the context in which the monitoring is performed. The audit should be considered and the audit should be followed. ### The Role of the Quality The quality is the context in which the monitoring is performed. The quality should be considered and the quality should be followed. ### The Role of the Safety The safety is the context in which the monitoring is performed. The safety should be considered and the safety should be followed. ### The Role of the Welfare The welfare is the context in which the monitoring is performed. The welfare should be considered and the welfare should be followed. ### The Role of the Ethics The ethics is the context in which the monitoring is performed. The ethics should be considered and the ethics should be followed. ### The Role of the Law The law is the context in which the monitoring is performed. The law should be considered and the law should be followed. ### The Role of the Regulation The regulation is the context in which the monitoring is performed. The regulation should be considered and the regulation should be followed. ### The Role of the Standard The standard is the context in which the monitoring is performed. The standard should be considered and the standard should be followed. ### The Role of the Guideline The guideline is the context in which the monitoring is performed. The guideline should be considered and the guideline should be followed. ### The Role of the Protocol The protocol is the context in which the monitoring is performed. The protocol should be considered and the protocol should be followed. ### The Role of the Procedure The procedure is the context in which the monitoring is performed. The procedure should be considered and the procedure should be followed. ### The Role of the Process The process is the context in which the monitoring is performed. The process should be considered and the process should be followed. ### The Role of the System The system is the context in which the monitoring is performed. The system should be considered and the system should be followed. ### The Role of the Framework The framework is the context in which the monitoring is performed. The framework should be considered and the framework should be followed. ### The Role of the Model The model is the context in which the monitoring is performed. The model should be considered and the model should be followed. ### The Role of the Approach The approach is the context in which the monitoring is performed. The approach should be considered and the approach should be followed. ### The Role of the Method The method is the context in which the monitoring is performed. The method should be considered and the method should be followed. ### The Role of the Technique The technique is the context in which the monitoring is performed. The technique should be considered and the technique should be followed. ### The Role of the Tool The tool is the context in which the monitoring is performed. The tool should be considered and the tool should be followed. ### The Role of the Instrument The instrument is the context in which the monitoring is performed. The instrument should be considered and the instrument ## Frequently Asked Questions ### What is the difference between total calcium and ionized calcium? Total calcium includes the protein-bound and free ionized fractions. Ionized calcium is the physiologically active fraction that affects cellular functions. The ionized calcium is the value that should guide clinical decisions when available. ### Why is ionized calcium measurement important in hypercalcemia? Ionized calcium measurement is important because total calcium can be misleading in patients with abnormal protein concentrations. The ionized calcium is the biologically active fraction and is the value that should guide clinical decisions. ### What is the role of PTH in the diagnosis of hypercalcemia? PTH is the primary regulator of calcium. In primary hyperparathyroidism, PTH is elevated despite the hypercalcemia. In malignancy-associated hypercalcemia, PTH is suppressed because the tumor secretes PTHrP. ### What is the role of PTHrP in the diagnosis of hypercalcemia? PTHrP is a protein that is secreted by certain tumors. It produces hypercalcemia by increasing bone resorption and renal calcium reabsorption. A positive PTHrP measurement in a patient with hypercalcemia indicates malignancy. ### What are the common causes of hypercalcemia in dogs and cats? The common causes of hypercalcemia in dogs and cats are primary hyperparathyroidism, malignancy-associated hypercalcemia, and chronic kidney disease. The diagnosis is based on the PTH and PTHrP measurements. ### What are the common causes of hypocalcemia in dogs and cats? The common causes of hypocalcemia in dogs and cats are primary hypoparathyroidism, hypomagnesemia, and chronic kidney disease. The diagnosis is based on the PTH and magnesium measurements. ### How should a sample be handled for ionized calcium measurement? The sample should be collected in a tube without EDTA and analyzed within 30 to 60 minutes of collection. The sample should be separated from the clot and analyzed promptly. ### When should a clinician escalate a calcium or phosphorus case to a specialist? The clinician should escalate the case when the diagnosis is not clear, the patient is not responding to treatment, or the patient requires advanced imaging or surgery. The specialist can provide the expertise needed to manage the patient. ## Related Veterinary Guides - [Diagnostic Approach to Neurological Disease in Swine: Differentiating Viral, Bacterial, and Toxic Causes](/knowledge/veterinary-medicine/food-animal-medicine/diagnostic-approach-neurological-disease-swine-viral-bacterial-toxic) - [Diagnostic Approach to Respiratory Disease in Poultry: Differentiating Viral, Bacterial, and Fungal Causes](/knowledge/veterinary-medicine/food-animal-medicine/diagnostic-approach-respiratory-disease-poultry-viral-bacterial-fungal) - [Diagnostic Approach to Acute Abdomen in Dogs and Cats](/knowledge/veterinary-medicine/veterinary-surgery/diagnostic-approach-acute-abdomen-dogs-cats) - [Diagnostic Approach to Respiratory Disease in Sheep and Goats](/knowledge/veterinary-medicine/food-animal-medicine/diagnostic-approach-respiratory-disease-sheep-goats) - [Canine Lung Disease: Differential Diagnosis and Diagnostic Approach](/knowledge/veterinary-medicine/clinical-internal-medicine/canine-lung-disease-differential-diagnosis-diagnostic-approach) ## References and Further Reading - [Pet Care](https://www.avma.org/resources-tools/pet-owners). American Veterinary Medical Association. - [AAHA Guidelines](https://www.aaha.org/resources). American Animal Hospital Association. - [Global Guidelines](https://wsava.org/global-guidelines). World Small Animal Veterinary Association. - [Merck Veterinary Manual](https://www.merckvetmanual.com/). Merck Veterinary Manual. - [Cornell University College of Veterinary Medicine](https://www.vet.cornell.edu/). Cornell University. - [Animal Health and Welfare](https://www.woah.org/en/what-we-do/animal-health-and-welfare). World Organisation for Animal Health. - [Endocrine causes of calcium disorders.](https://pubmed.ncbi.nlm.nih.gov/23415381). Topics in companion animal medicine, 2012. - [Treatment of calcium, phosphorus, and magnesium balance disorders.](https://pubmed.ncbi.nlm.nih.gov/10573815). The Veterinary clinics of North America. Food animal practice, 1999. - [Therapeutic approach to electrolyte emergencies.](https://pubmed.ncbi.nlm.nih.gov/18402878). The Veterinary clinics of North America. Small animal practice, 2008. - [Bilateral Global Nephrocalcinosis in a Uremic Puppy.](https://pubmed.ncbi.nlm.nih.gov/39195792). Veterinary sciences, 2024. - [Miscellaneous conditions of the equine head.](https://pubmed.ncbi.nlm.nih.gov/8472203). The Veterinary clinics of North America. Equine practice, 1993. > This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.