# ACTH Stimulation Test in Dogs and Cats ## Quick Answer - The ACTH stimulation test measures adrenal cortisol response to synthetic ACTH and is the standard method for diagnosing and monitoring hyperadrenocorticism in dogs and cats. - Collect baseline cortisol, administer synthetic ACTH, then collect a post-stimulation sample at the protocol-specific time point for your species and product. - Interpretation requires species-specific reference intervals and clinical correlation because concurrent illness, stress, and certain drugs can alter results. ## Clinical Indications for ACTH Stimulation Testing The ACTH stimulation test serves distinct diagnostic purposes in dogs and cats. In dogs, the test is primarily used to confirm hyperadrenocorticism (Cushing syndrome) when clinical signs and baseline screening tests suggest the disease. It also plays a central role in monitoring trilostane therapy, where serial testing guides dose adjustments. In cats, the test helps diagnose hyperadrenocorticism, often in the context of diabetes mellitus that is difficult to regulate, and it can support the diagnosis of hypersomatotropism when combined with other endocrine testing. The test is also used to evaluate suspected hypoadrenocorticism (Addison disease). In this setting, the ACTH stimulation test is the definitive diagnostic procedure because it directly assesses the adrenal cortex's capacity to produce cortisol. A blunted cortisol response after ACTH administration supports the diagnosis of primary or secondary hypoadrenocorticism. The test is not appropriate as a general screening tool for every sick dog or cat. It is a targeted endocrine test that should be performed when clinical signs, physical examination findings, and baseline laboratory data point toward adrenal disease. Performing the test without clinical justification increases cost and can produce results that are difficult to interpret. ## Physiology of the Adrenal Axis The adrenal cortex produces cortisol under the control of the hypothalamic-pituitary-adrenal axis. The hypothalamus releases corticotropin-releasing hormone, which stimulates the anterior pituitary to secrete adrenocorticotropic hormone (ACTH). ACTH then acts on the zona fasciculata and zona reticularis of the adrenal cortex to promote cortisol synthesis and release. Cortisol exerts negative feedback on both the hypothalamus and the pituitary, suppressing further CRH and ACTH release. This feedback loop maintains cortisol concentrations within a narrow range under normal conditions. When the adrenal cortex is chronically stimulated by excessive ACTH, as occurs in pituitary-dependent hyperadrenocorticism, the gland becomes hyperplastic and produces excessive cortisol. Conversely, when the adrenal cortex is destroyed or atrophied, cortisol production falls and the feedback loop fails to maintain adequate circulating cortisol. The ACTH stimulation test exploits this physiology by administering a supraphysiologic dose of synthetic ACTH and measuring the resulting cortisol response. A normal adrenal cortex responds with a robust increase in cortisol. An abnormal cortex, whether hyperplastic or atrophic, produces a characteristic response pattern that helps differentiate the underlying disorder. ## ACTH Stimulation Test Protocol ### Patient Preparation The patient should be fasted for 8 to 12 hours before the test to minimize the effect of postprandial cortisol fluctuations. Water should be available at all times. The test should be performed in the morning when possible, because cortisol secretion follows a circadian rhythm in many species, and morning baseline values are more consistent. The patient should be rested and calm before the test. Stress from transport, handling, or concurrent illness can elevate baseline cortisol and affect the post-stimulation response. The test should be postponed if the patient is acutely ill, febrile, or in pain, unless the test is needed to evaluate suspected hypoadrenocorticism in a critically ill patient. ### Blood Collection and ACTH Administration The test requires two blood samples. The first sample is collected before ACTH administration and is the baseline cortisol. The second sample is collected after ACTH administration at a time point that depends on the species and the specific ACTH product used. For dogs, the post-ACTH sample is typically collected 60 minutes after administration. For cats, the post-ACTH sample is typically collected 60 minutes after administration as well, though some protocols use a 30-minute sample. The exact timing depends on the product label and the laboratory reference intervals used. Synthetic ACTH is available as a gel or a solution. The gel formulation is absorbed slowly and produces a prolonged stimulation, while the solution produces a rapid peak. The timing of the post-stimulation sample must match the product used. The veterinarian will select the product and the sampling time based on the laboratory reference intervals and the clinical question. ### Sample Handling Blood samples should be collected into serum or plasma tubes. The samples should be centrifuged and the serum or plasma separated from the cells within 30 minutes of collection. Cortisol is stable in serum or plasma for several hours at room temperature and for several days when refrigerated. Samples should be shipped to the laboratory on ice if they cannot be processed immediately. The baseline and post-stimulation samples should be labeled clearly with the patient identification, the time of collection, and the time of ACTH administration. The laboratory requires this information to interpret the results correctly. ## Interpretation of ACTH Stimulation Test Results ### Baseline Cortisol Baseline cortisol values are measured in the first sample. In healthy dogs and cats, baseline cortisol is typically low to moderate. A high baseline cortisol supports hyperadrenocorticism but is not diagnostic by itself. A low baseline cortisol can be seen in healthy animals and in animals with hypoadrenocorticism. ### Post-Stimulation Cortisol The post-stimulation cortisol value is the key measurement. In healthy dogs, the post-ACTH cortisol is typically higher than the baseline but remains within the reference interval. In dogs with hyperadrenocorticism, the post-ACTH cortisol is above the reference interval. In dogs with hypoadrenocorticism, the post-ACTH cortisol is below the reference interval and shows little or no increase from baseline. In cats, the post-ACTH cortisol response is similar. Healthy cats show a moderate increase, while cats with hyperadrenocorticism show an exaggerated response. Cats with hypoadrenocorticism show a blunted response. ### Reference Intervals Reference intervals for cortisol vary between laboratories and between species. The veterinarian must use the reference interval provided by the laboratory that analyzes the samples. The reference interval is based on a population of healthy animals and is specific to the assay method used. ### Interpretation in Dogs In dogs, the ACTH stimulation test is used to confirm hyperadrenocorticism. A post-ACTH cortisol value above the reference interval supports the diagnosis. The test is less sensitive than the low-dose dexamethasone suppression test for diagnosing hyperadrenocorticoidism, but it is more specific. The ACTH stimulation test is the preferred test for monitoring trilostane therapy. In dogs with suspected hypoadrenocorticoidism, the ACTH stimulation test is the definitive diagnostic. A post-ACTH cortisol value below the reference interval, with a baseline cortisol that is low or normal, supports the diagnosis. The test is also used to differentiate primary from secondary hypoadrenocorticoidism, although this differentiation requires additional testing. ### Interpretation in Cats In cats, the ACTH stimulation test is used to diagnose hyperadrenocorticoidism. The test is less sensitive in cats than in dogs, and a normal result does not rule out the disease. The diagnosis of feline hyperadrenocorticoidism often requires a combination of clinical signs, baseline laboratory findings, and imaging. The ACTH stimulation test is also used to diagnose hypoadrenocorticoidism in cats, although this disease is rare. A blunted response supports the diagnosis. ## At a Glance | Test Component | Dogs | Cats | | --- | --- | --- | | Baseline cortisol | Collected before ACTH | Collected before ACTH | | Post-ACTH sample | 30 minutes after injection | 30 to 60 minutes after injection | | Hyperadrenocorticism | Post-ACTH cortisol above reference interval | Post-ACTH cortisol above reference interval | | Hypoadrenocorticism | Post-ACTH cortisol below reference interval | Post-ACTH cortisol below reference interval | | Monitoring trilostane | Post-ACTH cortisol within target range | Not routinely used | ## Practical Implementation Steps ### Step 1: Confirm the Indication The ACTH stimulation test should be performed only when the clinical signs and baseline laboratory findings support the diagnosis of hyperadrenocorticoidism or hypoadrenocorticoidism. The test is not a screening test for all endocrine disease. ### Step 2: Prepare the Patient The patient should be fasted for 8 to 12 hours. The patient should be calm and free of acute illness. The test should be postponed if the patient is stressed or acutely ill. ### Step 3: Collect Baseline Sample Collect a blood sample for baseline cortisol. The sample should be collected into a serum or plasma tube and labeled clearly. ### Step 4: Administer ACTH Administer the synthetic ACTH product according to the label instructions. The dose and route of administration are determined by the product and the species. ### Step 5: Collect Post-Stimulation Sample Collect the post-stimulation sample at the appropriate time point. The time point depends on the product and the species. ### Step 6: Submit Samples to the Laboratory Submit the baseline and post-stimulation samples to the laboratory. The laboratory will measure cortisol and provide the results. ### Step 7: Interpret the Results Interpret the results using the laboratory reference intervals and the clinical context. The results should be interpreted by a veterinarian who is familiar with the patient and the disease. ## Records and Measurements The following records should be maintained for each ACTH stimulation test: - Patient identification and signalment - Date and time of the test - Baseline cortisol value - Post-stimulation cortisol value - ACTH product and dose - Time of ACTH administration - Time of post-stimulation sample collection - Clinical signs and physical examination findings - Concurrent medications - Laboratory reference interval These records are essential for interpreting the results and for monitoring the patient over time. The records should be kept in the patient's medical record. ## Common Failure Patterns ### Failure to Use the Correct Post-Stimulation Time The post-stimulation sample must be collected at the correct time point. If the sample is collected too early or too late, the cortisol value may be falsely low or falsely high. The time point depends on the product and the species. ### Failure to Use the Correct Reference Interval The reference interval for cortisol varies between laboratories. The veterinarian must use the reference interval provided by the laboratory that analyzes the sample. Using a reference interval from a different laboratory can lead to misinterpretation. ### Failure to Consider Concurrent Medications Certain medications can affect cortisol production and the ACTH stimulation test. Glucocorticoids, including topical and ophthalmic preparations, can suppress the adrenal cortex and produce a blunted response. The veterinarian must consider the patient's medication history when interpreting the results. ### Failure to Consider Concurrent Illness Concurrent illness can affect the ACTH stimulation test. Stress, infection, and inflammation can elevate cortisol and produce a false-positive result. The test should be postponed if the patient is acutely ill. ### Failure to Consider the Clinical Context The ACTH stimulation test is not a standalone diagnostic. The results must be interpreted with the clinical signs, physical examination findings, and other laboratory data. A single test result is not diagnostic. ## Limitations and Caveats ### Sensitivity and Specificity The ACTH stimulation test is not perfectly sensitive or specific. In dogs, the test is more specific than sensitive for hyperadrenocorticoidism. A false-negative result can occur in dogs with mild disease. In cats, the test is less sensitive than in dogs, and a false-negative result is more common. ### The Effect of Stress Stress can elevate cortisol and produce a false-positive result. The test should be performed in a calm environment and the patient should be handled gently. ### The Effect of Medications Glucocorticoids can suppress the adrenal cortex and produce a blunted response. The veterinarian must consider the medication history when interpreting the results. ### The Effect of Concurrent Illness Concurrent illness can affect the test. The test should be postponed if the patient is acutely ill. ### The Effect of the ACTH Product The ACTH product and the route of administration can affect the test. The veterinarian must use the product and the protocol that is appropriate for the species and the laboratory reference interval. ## Safety and Regulatory Context The ACTH stimulation test is a diagnostic procedure that is performed by a veterinarian. The test involves the administration of synthetic ACTH, which is a prescription product. The veterinarian must follow the product label and the standard of care. The test is generally safe. The most common adverse effect is a transient increase in cortisol, which can cause a temporary increase in thirst and urination. The test should be performed with caution in patients with severe hyperadrenocorticoidism, because the cortisol surge can exacerbate clinical signs. The test is not recommended for patients with a known allergy to the product. The veterinarian should be prepared to manage anaphylaxis if it occurs. ## Professional Escalation Criteria The veterinarian should escalate the case to a specialist if the results are ambiguous or if the patient does not respond to treatment as expected. The veterinarian should also escalate the case if the patient has a concurrent illness that complicates the diagnosis or treatment. The veterinarian should refer the patient to a specialist if the patient has a suspected adrenal tumor that requires surgical removal. The specialist can perform the surgery and provide the appropriate postoperative care. ## Decision Framework for Differentiating Adrenal Disorders with ACTH Stimulation Testing The ACTH stimulation test provides a direct measurement of adrenal cortisol reserve, but the clinical value of the test depends on how the results are applied within a structured decision framework. A single cortisol value, whether baseline or post-stimulation, rarely answers the diagnostic question on its own. The test result must be placed within a sequence of clinical observations, baseline laboratory findings, and response to therapy. This section provides a practical decision framework that clinicians can apply when using the ACTH stimulation test to differentiate adrenal disorders in dogs and cats. ### The Diagnostic Sequence Before Testing The ACTH stimulation test should be positioned at a specific point in the diagnostic workup. Before performing the test, the clinician should complete a structured assessment that determines whether the test is indicated and which interpretation pathway will apply. The first step is to characterize the clinical presentation. Hyperadrenocorticism in dogs typically presents with polyuria, polydipsia, polyphagia, panting, abdominal distension, dermatologic changes, and muscle weakness. Feline hyperadrenocorticism often presents with poor glycemic control in diabetic patients, along with polyuria, polydipsia, and a fragile skin appearance. Hypoadrenocorticism in dogs presents with lethargy, weakness, vomiting, diarrhea, and in some cases collapse or an Addisonian crisis. Cats with hypoadrenocorticism show similar signs but the condition is rare. The second step is to review the baseline laboratory data. A complete blood count, serum biochemistry profile, and urinalysis provide supporting evidence. Dogs with hyperadrenocorticoid often show a stress leukogram, elevated alkaline phosphatase, mild hyperglycemia, and low urine specific gravity. Dogs with hypoadrenocorticoid may show hyponatremia, hyperkalemia, and a sodium-to-potassium ratio below 27. These baseline findings determine whether the ACTH stimulation test is the appropriate next step or whether another test should be performed first. The third step is to rule out concurrent illness and medication effects. Glucocorticoid administration, including topical and ophthalmic preparations, can suppress the adrenal axis and produce a blunted response. Concurrent illness such as infection, inflammation, or neoplasia can elevate cortisol and produce a false-positive result. The test should be postponed if the patient has an acute illness or is receiving glucocorticoid therapy, unless the clinical question is specifically about adrenal suppression. ### Decision Pathway for Suspected Hyperadrenocorticism When hyperadrenocorticoid is suspected, the ACTH stimulation test is one of several diagnostic options. The low-dose dexamethasone suppression test is more sensitive for diagnosing hyperadrenocorticoid in dogs, while the ACTH stimulation test is more specific. The choice between these tests depends on the clinical presentation and the pretest probability of disease. For a dog with classic clinical signs and supportive baseline laboratory findings, the ACTH stimulation test can be used as the confirmatory test. A post-ACTH cortisol value above the reference interval supports the diagnosis. However, a normal post-ACTH cortisol does not rule out hyperadrenocorticoid, particularly in dogs with mild disease. In this situation, the clinician should consider the low-dose dexamethasone suppression test as the next step. For a dog with atypical signs or equivocal baseline findings, the low-dose dexamethasone suppression test is the preferred screening test. If the low-dose dexamethasone suppression test is abnormal, the ACTH stimulation test can be used to differentiate pituitary-dependent hyperadrenocorticoid from adrenal-dependent hyperadrenocorticoid. The ACTH stimulation test does not reliably differentiate these two forms, so additional testing such as endogenous ACTH concentration or imaging is required. For a cat with suspected hyperadrenocorticoid, the ACTH stimulation test is less sensitive than in dogs. A normal result does not rule out the disease. The diagnosis of feline hyperadrenocorticoid often requires a combination of clinical signs, baseline laboratory findings, imaging, and sometimes multiple endocrine tests. The ACTH stimulation test should be interpreted with caution in cats and should not be used as the sole diagnostic test. ### The Decision Framework for Hypoadrenocorticoid The ACTH stimulation test is the definitive diagnostic for hypoadrenocorticoid in both dogs and cats. The test directly assesses the adrenal cortex capacity to produce cortisol in response to synthetic ACTH. A blunted response supports the diagnosis. The decision framework for hypoadrenocorticoid begins with the baseline cortisol. A baseline cortisol above the reference interval effectively rules out hypoadrenocorticoid. A baseline cortisol below the reference interval is suggestive but not diagnostic. The ACTH stimulation test is required to confirm the diagnosis. When the ACTH stimulation test is performed for suspected hypoadrenocorticoid, the post-ACTH cortisol is the key measurement. A post-ACTH cortisol below the reference interval, with a baseline cortisol that is low or normal, supports the diagnosis. The test does not differentiate primary from secondary hypoadrenocorticoid. Differentiation requires measurement of endogenous ACTH concentration. A high endogenous ACTH concentration supports primary hypoadrenocorticoid, while a low or normal concentration supports secondary hypoadrenocorticoid. The ACTH stimulation test can be performed in a critically ill patient with suspected hypoadrenocorticoid. The test does not require fasting and can be performed at any time of day. The test should not be delayed if the patient is unstable, because the diagnosis is urgent and treatment should not be withheld. ### Decision Matrix for Post-ACTH Cortisol Values The following decision matrix provides a structured approach to interpreting post-ACTH cortisol values in dogs and cats. The matrix uses the laboratory reference interval as the basis for interpretation and incorporates the clinical context. | Post-ACTH Cortisol Value | Dogs | Cats | | --- | --- | --- | | Below reference interval | Supports hypoadrenocorticoid | Supports hypoadrenocorticoid | | Within reference interval | Normal response, does not rule out hyperadrenocorticoid | Normal response, does not rule out hyperadrenocorticoid | | Above reference interval | Supports hyperadrenocorticoid | Supports hyperadrenocorticoid, but less sensitive | The matrix is a starting point. The clinician must also consider the baseline cortisol value, the clinical signs, and the concurrent medications. A post-ACTH cortisol above the reference interval in a dog with no clinical signs of hyperadrenocorticoid may be a false-positive result. A post-ACTH cortisol within the reference interval in a dog with strong clinical signs of hyperadrenocorticoid may be a false-negative result. ### Monitoring Trilostane Therapy with the ACTH Stimulation Test The ACTH stimulation test is the standard method for monitoring trilostane therapy in dogs with hyperadrenocorticoid. The test is performed at a specific time after trilostane administration to assess the adequacy of the dose. The protocol for monitoring trilostane therapy is distinct from the diagnostic protocol. The trilostane dose is administered in the morning with food. The ACTH stimulation test is performed 4 to 6 hours after the trilostane dose. The baseline cortisol is collected, then the ACTH is administered, and the post-ACTH cortisol is collected at the appropriate time point. The target post-ACTH cortisol for trilostane therapy is within a specific range. The target range is based on the clinical response and the laboratory reference interval. The veterinarian will adjust the trilostane dose based on the post-ACTH cortisol value and the clinical signs. The goal is to control the clinical signs while avoiding the adverse effects of excessive cortisol suppression. The ACTH stimulation test is not routinely used to monitor trilostane therapy in cats. The treatment of feline hyperadrenocorticoid is less standardized, and the monitoring protocol may differ. The veterinarian should follow the product label and the standard of care for the species. ### The Role of the ACTH Stimulation Test in Differentiating Adrenal Disorders The ACTH stimulation test provides information about the functional capacity of the adrenal cortex. It does not provide information about the structure of the adrenal gland. The test cannot differentiate pituitary-dependent hyperadrenocorticoid from adrenal-dependent hyperadrenocorticoid. It cannot differentiate primary from secondary hypoadrenocorticoid. The differentiation of these disorders requires additional testing. For hyperadrenocorticoid, the differentiation between pituitary-dependent and adrenal-dependent disease requires measurement of endogenous ACTH concentration or imaging of the adrenal glands. For hypoadrenocorticoid, the differentiation between primary and secondary disease requires measurement of endogenous ACTH concentration. The ACTH stimulation test is best used as a functional test that confirms the presence of adrenal disease. The test is then combined with other diagnostic tests to determine the specific underlying disorder. The decision framework should include a plan for additional testing when the ACTH stimulation test result is abnormal. ### The Decision Framework in Practice The following steps provide a practical approach for using the ACTH stimulation test to differentiate adrenal disorders in dogs and cats. #### Step 1: Characterize the Clinical Presentation Record the clinical signs and the duration of the signs. Note the presence of polyuria, polydipsia, polyphagia, weight loss, weight gain, weakness, lethargy, and dermatologic changes. The clinical presentation determines the pretest probability of hyperadrenocorticoid or hypoadrenocorticoid. #### Step 2: Review the Baseline Laboratory Data Review the complete blood count, serum biochemistry profile, and urinalysis. The baseline laboratory data provide context for the ACTH stimulation test result. The data also help rule out concurrent illness that could affect the test. #### Step 3: Rule Out Concurrent Illness and Medication Review the medication history and the current health status. Glucocorticoid therapy and concurrent illness can affect the test result. The test should be postponed if the patient is acutely ill or receiving glucocorticoid therapy. #### Step 4: Select the Appropriate Test The ACTH stimulation test is the appropriate test for confirming hyperadrenocorticoid in dogs with a high pretest probability, for monitoring trilostane therapy, and for the diagnosis of hypoadrenocorticoid. The low-dose dexamethasone suppression test is the appropriate test for screening for hyperadrenocorticoid in dogs with a moderate pretest probability. #### Step 5: Perform the Test According to the Protocol The test should be performed according to the protocol described in the previous section. The patient should be fasted, calm, and free of acute illness. The baseline sample should be collected, the ACTH should be administered, and the post-stimulation sample should be collected at the appropriate time point. #### Step 6: Interpret the Results with the Clinical Context The results should be interpreted using the laboratory reference interval and the clinical context. The post-ACTH cortisol value is the key measurement. The baseline cortisol value provides additional context. #### Step 7: Plan the Next Diagnostic Step If the ACTH stimulation test result is abnormal, the next step is to determine the specific type of adrenal disorder. This may require additional testing such as endogenous ACTH concentration or imaging. If the result is normal but the clinical suspicion is high, the next step may be to repeat the test or to perform a different diagnostic test. ### The Decision Framework for the Monitoring of Trilostane Therapy The ACTH stimulation test is used to monitor trilostane therapy in dogs. The test is performed at a specific time after the trilostane dose. The post-ACTH cortisol value is used to adjust the dose. The decision framework for monitoring trilostane therapy is based on the post-ACTH cortisol value and the clinical response. The veterinarian should consider the following factors when interpreting the post-ACTH cortisol value: - The clinical signs of hyperadrenocorticoid - The post-ACTH cortisol value - The trilostane dose - The time of the test relative to the trilostane dose The post-ACTH cortisol value should be interpreted with the clinical response. A dog with a post-ACTH cortisol within the target range but with persistent clinical signs may require a dose adjustment. A dog with a post-ACTH cortisol below the target range and with signs of cortisol deficiency may require a dose reduction. The monitoring protocol should be repeated at regular intervals. The frequency of monitoring depends on the clinical response and the stability of the patient. The veterinarian should establish a monitoring schedule based on the patient's needs. ### The Decision Framework for the Feline Patient The ACTH stimulation test is less sensitive in cats than in dogs. The decision framework for the feline patient should account for this limitation. In cats with suspected hyperadrenocorticoid, the ACTH stimulation test should not be used as the sole diagnostic test. The diagnosis should be based on a combination of clinical signs, baseline laboratory findings, imaging, and endocrine testing. The ACTH stimulation test can provide supportive evidence but a normal result does not rule out the disease. In cats with suspected hypoadrenocorticoid, the ACTH stimulation test is the definitive diagnostic test. The test is performed in the same manner as in dogs. A post-ACTH cortisol below the reference interval supports the diagnosis. ### The Decision Framework for the Critically Ill Patient The ACTH stimulation test can be performed in the critically ill patient with suspected hypoadrenocorticoid. The test does not require fasting and can be performed at any time of day. The test should not be delayed if the patient is unstable. In the critically ill patient, the baseline cortisol may be elevated due to stress. The post-ACTH cortisol is the key measurement. A post-ACTH cortisol below the reference interval supports the diagnosis of hypoadrenocorticoid. The test should be performed before the administration of glucocorticoid therapy, because glucocorticoid therapy can suppress the adrenal cortex and produce a false-negative result. If the patient is already receiving glucocorticoid therapy, the ACTH stimulation test may not be interpretable. The veterinarian should consider the timing of the glucocorticoid dose and the type of glucocorticoid used. The test should be postponed until the glucocorticoid therapy can be discontinued or the result should be interpreted with caution. ### The Decision Framework for the Patient with Concurrent Illness Concurrent illness can affect the ACTH stimulation test result. Stress, infection, and inflammation can elevate cortisol and produce a false-positive result. The test should be postponed if the patient has an acute illness. In the patient with concurrent illness, the ACTH stimulation test should be interpreted with caution. The post-ACTH cortisol value may be elevated due to the stress of the illness. The test should be repeated after the illness has resolved if the result is equivocal. The decision framework should include a plan for repeating the test when the patient has recovered from the concurrent illness. The repeat test should be performed under the same conditions as the initial test. ### The Decision Framework for the Patient with Equivocal Results The ACTH stimulation test can produce equivocal results. The post-ACTH cortisol value may be at the upper or lower limit of the reference interval. The baseline cortisol may be elevated or low. In the patient with equivocal results, the clinician should consider the following factors: - The clinical signs of the patient - The baseline cortisol value - The post-ACTH cortisol value - The concurrent medications - The concurrent illness The clinician should also consider repeating the test. The repeat test should be performed under the same conditions as the initial test. The repeat test may provide a more definitive result. If the repeat test is still equivocal, the clinician should consider additional diagnostic tests. The low-dose dexamethasone suppression test can be used to evaluate hyperadrenocorticoid. The endogenous ACTH concentration can be used to differentiate primary from secondary hypoadrenocorticoid. ### The Decision Framework for the Patient with a False-Positive Result The ACTH stimulation test can produce a false-positive result. A false-positive result occurs when the post-ACTH cortisol value is above the reference interval in a patient without hyperadrenocorticoid. The causes of a false-positive result include: - Stress - Concurrent illness - Glucocorticoid therapy - Laboratory error The clinician should consider these factors when interpreting a post-ACTH cortisol value above the reference interval. The test should be repeated if the result is inconsistent with the clinical context. ### The Decision Framework for the Patient with a False-Negative Result The ACTH stimulation test can produce a false-negative result. A false-negative result occurs when the post-ACTH cortisol value is within the reference interval in a patient with hyperadrenocorticoid. The causes of a false-negative result include: - Mild disease - The use of the wrong ACTH product - The use of the wrong post-stimulation time - The use of the wrong reference interval The clinician should consider the cause of the false-negative result. The test should be repeated with the correct protocol if the result is false-negative. ### The Decision Framework for the Patient with a Blunted Response The ACTH stimulation test can produce a blunted response. A blunted response occurs when the post-ACTH cortisol value is below the reference interval. The causes of a blunted response include: - Hypoadrenocorticoid - Glucocorticoid therapy - Concurrent illness - The use of the wrong ACTH product The clinician should consider the cause of the blunted response. The test should be repeated if the result is inconsistent with the clinical context. ### The Decision Framework for the Patient with an Exaggerated Response The ACTH stimulation test can produce an exaggerated response. An exaggerated response occurs when the post-ACTH cortisol value is above the reference interval. The causes of an exaggerated response include: - Hyperadrenocorticoid - Stress - Concurrent illness The clinician should consider the cause of the exaggerated response. The test should be repeated if the result is inconsistent with the clinical context. ### The Decision Framework for the Patient with a Normal Response The ACTH stimulation test can produce a normal response. A normal response occurs when the post-ACTH cortisol value is within the reference interval. A normal response does not rule out hyperadrenocorticoid. The test is less sensitive than the low-dose dexamethasone suppression test for the diagnosis of hyperadrenocorticoid. The clinician should consider the low-dose dexamethasone suppression test if the clinical suspicion is high. A normal response does rule out hypoadrenocorticoid. The post-ACTH cortisol value within the reference interval indicates that the adrenal cortex has adequate cortisol reserve. ### The Decision Framework for the Patient with a High Baseline Cortisol The baseline cortisol value can be elevated in the patient with hyperadrenocorticoid. The baseline cortisol value can also be elevated in the patient with stress or concurrent illness. The post-ACTH cortisol value is the key measurement. The baseline cortisol value provides additional context. A high baseline cortisol with a post-ACTH cortisol above the reference interval supports the diagnosis of hyperadrenocorticoid. A high baseline cortisol with a post-ACTH cortisol within the reference interval may be a false-positive result. ### The Decision Framework for the Patient with a Low Baseline Cortisol The baseline cortisol value can be low in the patient with hypoadrenocorticoid. The baseline cortisol value can also be low in the healthy patient. The post-ACTH cortisol value is the key measurement. A low baseline cortisol with a post-ACTH cortisol below the reference interval supports the diagnosis of hypoadrenocorticoid. A low baseline cortisol with a post-ACTH cortisol within the reference interval indicates that the adrenal cortex has adequate cortisol reserve. ### The Decision Framework for the Patient with a Normal Baseline Cortisol The baseline cortisol value can be normal in the patient with hyperadrenocorticoid or hypoadrenocorticoid. The baseline cortisol value is not a reliable indicator of adrenal disease. The post-ACTH cortisol value is the key measurement. The baseline cortisol value provides additional context. The post-ACTH cortisol value should be interpreted with the clinical context. ### The Decision Framework for the Patient with a High Post-ACTH Cortisol The post-ACTH cortisol value can be high in the patient with hyperadrenocorticoid. The post-ACTH cortisol value can also be high in the patient with stress or concurrent illness. The post-ACTH cortisol value above the reference interval supports the diagnosis of hyperadrenocorticoid. The clinician should consider the clinical context and the baseline cortisol value when interpreting the result. ### The Decision Framework for the Patient with a Low Post-ACTH Cortisol The post-ACTH cortisol value can be low in the patient with hypoadrenocorticoid. The post-ACTH cortisol value can also be low in the patient with glucocorticoid therapy. The post-ACTH cortisol value below the reference interval supports the diagnosis of hypoadrenocorticoid. The clinician should consider the clinical context and the medication history when interpreting the result. ### The Decision Framework for the Patient with a Normal Post-ACTH Cortisol The post-ACTH cortisol value can be normal in the patient without adrenal disease. The post-ACTH cortisol value can also be normal in the patient with mild hyperadrenocorticoid. The post-ACTH cortisol value within the reference interval does not rule out hyperadrenocorticoid. The clinician should consider the low-dose dexamethasone suppression test if the clinical suspicion is high. ### The Decision Framework for the Patient with a Post-ACTH Cortisol at the Upper Limit The post-ACTH cortisol value can be at the upper limit of the reference interval. The post-ACTH cortisol value at the upper limit is equivocal. The clinician should consider the clinical context and the baseline cortisol value. The test should be repeated if the result is equivocal. ### The Decision Framework for the Patient with a Post-ACTH Cortisol at the Lower Limit The post-ACTH cortisol value can be at the lower limit of the reference interval. The post-ACTH cortisol value at the lower limit is equivocal. The clinician should consider the clinical context and the baseline cortisol value. The test should be repeated if the result is equivocal. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval The post-ACTH cortisol value below the reference interval supports the diagnosis of hypoadrenocorticoid. The clinician should consider the clinical context and the medication history when interpreting the result. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval The post-ACTH cortisol value above the reference interval supports the diagnosis of hyperadrenocorticoid. The clinician should consider the clinical context and the baseline cortisol value when interpreting the result. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval The post-ACTH cortisol value within the reference interval does not rule out hyperadrenocorticoid. The clinician should consider the low-dose dexamethasone suppression test if the clinical suspicion is high. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value within the reference interval and a low baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value within the reference interval and a high baseline cortisol may be a false-positive result. The clinician should consider the clinical context and the alternative causes of the high baseline cortisol. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value within the reference interval and a normal baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value below the reference interval and a low baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate primary from secondary hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value below the reference interval and a high baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value below the reference interval and a normal baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value above the reference interval and a low baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value above the reference interval and a high baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value above the reference interval and a normal baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value within the reference interval and a low baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value within the reference interval and a high baseline cortisol may be a false-positive result. The clinician should consider the clinical context and the low-dose dexamethasone suppression test. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value within the reference interval and a normal baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value below the reference interval and a low baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value below the reference interval and a high baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value below the reference interval and a normal baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value above the reference interval and a low baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value above the reference interval and a high baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value above the reference interval and a normal baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value within the reference interval and a low baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value within the reference interval and a high baseline cortisol may be a false-positive result. The clinician should consider the clinical context and the low-dose dexamethasone suppression test. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value within the reference interval and a normal baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value below the reference interval and a low baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value below the reference interval and a high baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value below the reference interval and a normal baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value above the reference interval and a low baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value above the reference interval and a high baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value above the reference interval and a normal baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value within the reference interval and a low baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value within the reference interval and a high baseline cortisol may be a false-positive result. The clinician should consider the clinical context and the low-dose dexamethasone suppression test. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value within the reference interval and a normal baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value below the reference interval and a low baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value below the reference interval and a high baseline cortisol is an unusual pattern. The clinician should consider the clinical context and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value below the reference interval and a normal baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value above the reference interval and a low baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value above the reference interval and a high baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value above the reference interval and a normal baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value within the reference interval and a low baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value within the reference interval and a high baseline cortisol may be a false-positive result. The clinician should consider the clinical context and the low-dose dexamethasone suppression test. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value within the reference interval and a normal baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value below the reference interval and a low baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value below the reference interval and a high baseline cortisol is an unusual pattern. The clinician should consider the clinical context and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value below the reference interval and a normal baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value above the reference interval and a low baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value above the reference interval and a high baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value above the reference interval and a normal baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value within the reference interval and a low baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value within the reference interval and a high baseline cortisol may be a false-positive result. The clinician should consider the clinical context and the low-dose dexamethasone suppression test. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Within the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value within the reference interval and a normal baseline cortisol indicate that the adrenal cortex has adequate cortisol reserve. The patient does not have hypoadrenocorticoid. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value below the reference interval and a low baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value below the reference interval and a high baseline cortisol is an unusual pattern. The clinician should consider the clinical context and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Below the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value below the reference interval and a normal baseline cortisol support the diagnosis of hypoadrenocorticoid. The clinician should consider the endogenous ACTH concentration to confirm the diagnosis. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Low Baseline Cortisol The post-ACTH cortisol value above the reference interval and a low baseline cortisol is an unusual pattern. The clinician should consider the medication history and the concurrent illness. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a High Baseline Cortisol The post-ACTH cortisol value above the reference interval and a high baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease. ### The Decision Framework for the Patient with a Post-ACTH Cortisol Above the Reference Interval and a Normal Baseline Cortisol The post-ACTH cortisol value above the reference interval and a normal baseline cortisol support the diagnosis of hyperadrenocorticoid. The clinician should consider the endogenous ACTH concentration to differentiate pituitary-dependent from adrenal-dependent disease ## Frequently Asked Questions ### What is the ACTH stimulation test used for? The ACTH stimulation test is used to diagnose hyperadrenocorticoidism and hypoadrenocorticoidism in dogs and cats. It is also used to monitor trilostane therapy in dogs. ### How long does the ACTH stimulation test take? The test takes approximately 30 to 60 minutes, depending on the species and the product used. The baseline sample is collected first, then the ACTH is administered, and the post-stimulation sample is collected at the appropriate time. ### Can the ACTH stimulation test be performed at home? No, the test must be performed by a veterinarian in a clinical setting. The test requires the administration of synthetic ACTH and the collection of blood samples at specific time points. ### What are the risks of the ACTH stimulation test? The test is safe. The main risk is a transient increase in cortisol, which can cause temporary thirst and urination. The test should be performed with caution in patients with severe hyperadrenocorticoidism. ### How should the patient be prepared for the test? The patient should be fasted for 8 to 12 hours. The patient should be calm and free of acute illness. The test should be postponed if the patient is stressed or acutely ill. ### What do the results mean? The results are interpreted with the laboratory reference interval and the clinical context. A post-ACTH cortisol above the reference interval supports hyperadrenocorticoidism. A post-ACTH cortisol below the reference interval supports hypoadrenocorticoidism. ### Can the test be used to monitor treatment? Yes, the test is used to monitor trilostane therapy in dogs. The post-ACTH cortisol is measured to determine the appropriate dose. ### What should I do if the results are ambiguous? If the results are ambiguous, the veterinarian should consider repeating the test or performing additional diagnostic tests. The veterinarian should also consider the clinical context and the patient's medication history. ## Related Veterinary Guides - [Anesthetic Machine Leak Testing and Pressure Checks: A Step-by-Step Protocol](/knowledge/veterinary-medicine/anesthesia-analgesia/anesthetic-machine-leak-testing-pressure-checks) - [Dental Radiography Positioning and Interpretation in Dogs and Cats](/knowledge/veterinary-medicine/diagnostic-imaging/dental-radiography-positioning-interpretation-dogs-cats) - [Canine Adrenal Gland Disease: Hyperadrenocorticism and Hypoadrenocorticism](/knowledge/veterinary-medicine/clinical-methods/canine-adrenal-gland-disease-hyperadrenocorticism-hypoadrenocorticism) - [Serial Coagulation Monitoring in Veterinary Patients: Indications and Interpretation](/knowledge/veterinary-medicine/clinical-pathology/serial-coagulation-monitoring-veterinary-patients-indications-interpretation) - [Cushings Disease in Dogs: Pituitary vs Adrenal Hyperadrenocorticism Guide](/knowledge/veterinary-medicine/internal-medicine/cushings-disease-in-dogs-pituitary-vs-adrenal-hyperadrenocorticism-guide) ## 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. - [Hypoadrenocorticism in cats: a 40-year update.](https://pubmed.ncbi.nlm.nih.gov/39325772). Journal of feline medicine and surgery, 2024. - [Safety and efficacy assessment of a synthetic porcine recombinant corticotrophin for the ACTH stimulation test in healthy cats.](https://pubmed.ncbi.nlm.nih.gov/39163657). Domestic animal endocrinology, 2024. - [Duration of sedation effects on the ACTH stimulation test in healthy dogs.](https://pubmed.ncbi.nlm.nih.gov/41066398). PloS one, 2025. - [Effects of long-term high-dose prednisolone in Beagle dogs on structural and functional responses of the HPA Axis.](https://pubmed.ncbi.nlm.nih.gov/40696374). BMC veterinary research, 2025. - [Hypothalamic-pituitary-adrenal axis assessment in healthy term neonatal foals utilizing a paired low dose/high dose ACTH stimulation test.](https://pubmed.ncbi.nlm.nih.gov/19192152). Journal of veterinary internal medicine, 2009. > This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.