# Prioritizing Differentials by Species and Signalment ## Key Takeaways - **Species is the primary filter:** Eliminate diagnoses that do not occur in the given species due to fundamental anatomic, physiologic, or immunologic differences; for example, hypertrophic cardiomyopathy is a primary concern in felines, not ruminants. - **Breed modifies probability for predisposed conditions:** Utilize breed-associated disease lists for inherited and breed-predisposed conditions, recognizing that mechanisms range from single-gene mutations to conformational risks, such as cervical vertebral instability in Doberman Pinschers. - **Age and life stage dictate disease prevalence:** Rank age-specific diseases first, with pediatric patients presenting with congenital anomalies and naive immune responses, while geriatric patients are more prone to neoplasia and chronic organ failure. - **Sex and reproductive status are critical modifiers:** Consider sex-limited diseases (e.g., pyometra in intact females) and sex-predisposed conditions, as well as hormonal and metabolic states like periparturient hypocalcemia in lactating dairy cows. - **Production class alters metabolic priorities and exposure risks:** Differentiate disease patterns based on production class; for instance, a lactating dairy cow with ketosis has a different differential list than a dry cow with fat cow syndrome, and feedlot steers have different risks than pasture-raised beef cattle. - **Signalment overrides presenting signs when conflicting:** When signalment and presenting signs diverge, the signalment typically narrows the differential list and influences the order of diagnostic testing, but does not negate the importance of the presenting sign; for example, a young cat with hematuria suggests FLUTD or urolithiasis, while an older cat with hematuria raises suspicion for neoplasia or chronic kidney disease. --- The North American Veterinary Licensing Examination (NAVLE) tests clinical reasoning across the full breadth of domestic species, and one of its most consistent demands is the ability to rank differential diagnoses before ancillary testing is available. This article explains how to use species, breed, age, and sex as explicit filters when building and prioritizing a differential list for NAVLE questions. It serves veterinary students preparing for the examination and clinicians who want a structured framework for cross-species diagnostic reasoning. The central question addressed is straightforward: when a signalment is given, which diagnoses move to the top of the list, and which should be deprioritized or discarded? The examination itself is organized around clinical case presentations that span multiple species, with content distributed across the major domestic and food animal categories. The [ICVA NAVLE Candidate Information](https://www.icva.net/navle/) describes the examination structure and content areas, which include medicine, surgery, theriogenology, and public health across species. Because the test draws from a defined species list, students who can rapidly map a signalment to a short list of high-probability diagnoses gain a measurable advantage in both speed and accuracy. ## At a Glance | Parameter | Decision Rule | Example | |---|---|---| | Species | Eliminate diagnoses that do not occur in the species before considering prevalence | Hyperkalemic periodic paralysis is a horse diagnosis, not a dog diagnosis | | Breed | Use breed-associated disease lists for inherited and breed-predisposed conditions | Dalmatian with hyperuricemia and lower urinary tract signs | | Age | Classify the patient as pediatric, adult, or geriatric and rank age-specific diseases first | Neonatal sepsis versus adult-onset immune-mediated disease | | Sex | Consider sex-limited and sex-predisposed conditions | Periparturient hypocalcemia in dairy cows, not in bulls | | Reproductive status | Intact versus neutered changes risk for reproductive tract disease | Pyometra requires an intact uterus | | Production class | Lactation, pregnancy, and growth stage alter metabolic priorities | Lactating dairy cow with ketosis versus dry cow with fat cow syndrome | | Geographic or regional exposure | Use endemic disease patterns when the question provides a location | Heartworm in the southeastern United States versus the arid Southwest | ## The Logic of Signalment-Based Filtering Signalment is not a single data point. It is a set of intersecting probability modifiers that operate on the differential list before physical examination findings are considered. The underlying logic is Bayesian: each element of the signalment shifts the prior probability of each candidate diagnosis. A 6-month-old intact male Labrador Retriever with acute onset of hindlimb weakness has a different differential list than a 12-year-old spayed female Labrador with the same sign, even though the signalment shares breed and species. The species filter is the most powerful. Many diseases are species-specific because of anatomic, physiologic, or immunologic differences. Ruminants cannot develop hypertrophic cardiomyopathy as a primary disease in the same way cats do. Horses do not develop feline infectious peritonitis. Dogs do not develop bovine viral diarrhea. The [MSD Veterinary Manual](https://www.msdvetmanual.com/) organizes its clinical content by species precisely because the pathophysiologic frameworks differ so substantially across taxa. When a NAVLE question provides a species, the first step is to remove every diagnosis that cannot occur in that species, regardless of how well the clinical signs match. ## Breed as a Probability Modifier Breed information narrows the list further by introducing inherited and breed-predisposed conditions. These are also genetic curiosities. They represent diseases with high prevalence in specific breeds and near-zero prevalence in others. A 3-year-old male Doberman Pinscher with cervical weakness and proprioceptive deficits should trigger consideration of cervical vertebral instability, a condition with a strong breed association. The same signs in a 3-year-old mixed-breed dog would place that diagnosis much lower on the list. Breed associations are not limited to dogs. Cats have breed predispositions for hypertrophic cardiomyopathy in Maine Coon and Ragdoll breeds. Horses have breed associations for hyperkalemic periodic paralysis in Quarter Horses and related breeds. Cattle breeds differ in susceptibility to specific metabolic and infectious diseases. The student who memorizes breed lists without understanding the underlying mechanism will struggle when the question presents an atypical breed. The mechanism matters: some breed associations reflect single-gene mutations, others reflect conformational risk, and others reflect production traits such as milk yield that create metabolic vulnerability. ## Age and Life Stage Age filters operate on developmental and degenerative timelines. Pediatric patients have a differential list dominated by congenital anomalies, developmental orthopedic disease, and infectious diseases that exploit naive immune systems. Geriatric patients shift toward neoplasia, degenerative disease, and chronic organ failure. The transition points differ by species and by disease. A 2-year-old dog with lameness has a different list than a 10-year-old dog with the same lameness, but a 2-year-old horse and a 10-year-old horse have different lameness distributions again because of the species-specific effects of exercise and conformation. The [AAVMC veterinary education resources](https://www.aavmc.org/) emphasize the importance of life-stage medicine in the curriculum, reflecting that age-based reasoning is a core clinical competency instead of an examination trick. In NAVLE questions, age is often the single most discriminating piece of signalment when the presenting sign is common across many diseases. Seizures in a 6-month-old dog suggest congenital or metabolic causes. Seizures in a 9-year-old dog suggest intracranial neoplasia or metabolic disease. The same sign, the same species, and a different age produce a different prioritized list. ## Sex and Reproductive Status Sex filters operate through two distinct mechanisms. The first is anatomic: only females can develop pyometra, ovarian neoplasia, or dystocia. Only males can develop prostatic disease or testicular neoplasia. The second is hormonal and metabolic: pregnancy, lactation, and estrus create physiologic states that predispose to specific diseases. Periparturient hypocalcemia in dairy cows, pregnancy toxemia in ewes, and eclampsia in lactating bitches are all sex and reproductive status limited. Reproductive status matters independently of sex. An intact female dog with polyuria and polydipsia has pyometra on the differential list. A spayed female dog with the same signs does not, unless the spay was incomplete. An intact male cat with urethral obstruction has a different risk profile than a neutered male cat, though both can obstruct. The [AVMA practice resources](https://www.avma.org/resources-tools) address the clinical importance of reproductive status in routine practice, and the same logic applies to examination questions. When the question provides reproductive status, use it. When it does not, the absence of that information is itself a clue that the diagnosis may not depend on it. ## Species as a Primary Filter Species determines which organ systems are most likely to fail, which pathogens are endemic, and which physiologic norms apply. A 5-year-old cat with tachypnea and a 5-year-old horse with tachypnea share a clinical sign but almost no differential overlap. The cat's list begins with feline bronchial disease, cardiomyopathy, and pleural effusion. The horse's list begins with exercise-induced pulmonary hemorrhage, recurrent airway obstruction, and pleuropneumonia. The [ICVA NAVLE candidate information](https://www.icva.net/navle/) describes an examination built around species-specific clinical scenarios, and the [MSD Veterinary Manual](https://www.msdvetmanual.com/) organizes its content by species for the same reason: the species is the first and strongest probability filter. Species also dictates which diagnostic tests are feasible and which reference intervals apply. Serum creatinine in a Greyhound exceeds the general canine reference interval without indicating renal disease. Fibrinogen is a useful acute phase protein in cattle but has limited utility in cats. A reticulocyte count in a horse is difficult to interpret because equine reticulocytes are not released into circulation in the same pattern as in dogs. When a NAVLE question presents a species, the correct answer must respect that species' unique physiology, also its disease prevalence. ## Production Class and Use Within a species, production class changes the differential list substantially. A dairy cow with hypocalcemia is a different diagnostic problem than a beef cow with hypocalcemia, even though the metabolic disturbance is identical. The dairy cow's risk peaks in the first 24 to 48 hours after calving, while the beef cow's risk is lower because of lower milk production. The [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) emphasize that disease surveillance and control strategies differ by production system, and the same principle applies to individual diagnosis. Consider a 3-year-old intact male Holstein with anorexia and fever. The differential list includes traumatic reticuloperitonitis, pneumonia, and mastitis, but also hardware disease from ingested metal, which is more common in confinement-housed dairy cattle than in pasture-raised beef cattle. A 3-year-old intact male Angus on pasture with the same signs has a different risk profile: anaplasmosis, infectious bovine keratoconjunctivitis, and foot rot move up the list. Production class also affects which conditions are economically relevant and which diagnostic steps are justified. A feedlot steer with respiratory disease warrants treatment based on clinical signs and pen-side assessment, not on extensive imaging. A show animal or breeding animal may justify advanced diagnostics. The NAVLE expects you to recognize when the production context changes the diagnostic plan, also the differential list. ## Species-Specific Differential Tables The following table organizes common differentials by species and signalment category. Use it as a rapid reference when a question provides limited signalment information. | Species | Signalment Category | Presenting Sign | High-Priority Differentials | Lower-Priority Differentials | |---|---|---|---|---| | Canine | Young intact male | Stranguria | Urethral obstruction, urolithiasis, prostatitis | Neoplasia, neurogenic bladder | | Canine | Older intact male | Stranguria | Prostatic hyperplasia, prostatitis, prostatic neoplasia | Urethral obstruction, urolithiasis | | Feline | Young adult | Polyuria and polydipsia | Chronic kidney disease, hyperthyroidism, diabetes mellitus | Acromegaly, pyelonephritis | | Feline | Middle-aged to older | Polyuria and polydipsia | Hyperthyroidism, chronic kidney disease, diabetes mellitus | Acromegaly, hepatic disease | | Equine | Neonatal foal | Fever and diarrhea | Sepsis, rotavirus, clostridial enterocolitis | Salmonellosis, meconium impaction | | Equine | Adult horse | Acute colic | Large colon volvulus, gastric dilation, enterolithiasis | Sand impaction, inflammatory bowel disease | | Bovine | Periparturient dairy cow | Recumbency | Hypocalcemia, hypomagnesemia, toxic mastitis | Calving paralysis, musculoskeletal injury | | Bovine | Feedlot steer | Cough and fever | Bovine respiratory disease complex, lung abscess | Interstitial pneumonia, congestive heart failure | | Ovine | Young lamb | Neurologic signs | Polioencephalomalacia, listeriosis, pregnancy toxemia in ewes | Scrapie, tetanus | | Caprine | Adult doe | Weight loss and anemia | Hemonchosis, caseous lymphadenitis, caprine arthritis encephalitis | Johne's disease, malnutrition | | Porcine | Grower pig | Cyanosis and fever | Classical swine fever, erysipelas, salmonellosis | Porcine reproductive and respiratory syndrome, circovirus | | Avian | Young psittacine | Regurgitation and weight loss | Proventricular dilatation disease, chlamydiosis, aspergillosis | Bacterial enteritis, heavy metal toxicosis | ## Breed Modifiers Within Species Breed modifies probability within a species, and the NAVLE frequently tests breed predispositions that change the ranking of differentials. A 4-year-old Labrador Retriever with progressive hindlimb weakness has a list that includes fibrocartilaginous embolism, degenerative myelopathy, and intervertebral disc disease, but degenerative myelopathy is far more likely in this breed than in a Beagle of the same age. A 4-year-old Beagle with the same sign has a list that emphasizes intervertebral disc disease and fibrocartilaginous embolism. Breed also affects drug metabolism and anesthetic risk. A Collie with a MDR1 mutation may have prolonged sedation from ivermectin at doses that are safe in other breeds. A brachycephalic dog has higher anesthetic risk and a different airway management plan than a dolichocephalic dog. The [AVMA practice resources](https://www.avma.org/resources-tools) include breed-specific health guidance, and the NAVLE expects you to apply breed knowledge to both diagnosis and treatment planning. ## Age and Sex Interaction Age and sex interact with species to produce characteriztic disease patterns. A 6-month-old intact female cat with vomiting and diarrhea has a list that includes parasitism, dietary indiscretion, and feline panleukopenia. A 6-year-old intact female cat with the same signs has a list that includes chronic enteropathy, pancreatitis, and neoplasia. A 12-year-old intact female cat with the same signs has a list that includes lymphoma, chronic kidney disease, and hyperthyroidism. Sex and reproductive status matter most when the reproductive tract is involved, but they also affect non-reproductive disease risk. An intact male dog has a higher risk of perianal adenoma and prostatic disease. A neutered female dog has a higher risk of urinary incontinence and certain neoplasms. A pregnant mare has a different response to certain drugs and a different risk of colic than a non-pregnant mare. The NAVLE questions that include reproductive status are often testing whether you recognize that the reproductive tract is the source of the problem, also a coincidental finding. ## When Signalment Overrides Presenting Signs The most difficult NAVLE questions are those where the presenting sign points in one direction but the signalment points in another. A 10-year-old cat with weight loss and a heart murmur could have hyperthyroidism, chronic kidney disease, or cardiomyopathy. The signalment does not resolve the list, but it changes the order of testing. Hyperthyroidism is more likely in an older cat, and a thyroid panel is a reasonable first test. A 10-year-old dog with the same signs has a different list: chronic valvular disease, neoplasia, and hypothyroidism are all possible, but the diagnostic approach differs. When signalment and presenting signs conflict, the signalment usually narrows the list but does not eliminate the presenting sign's contribution. A 2-year-old cat with hematuria has a list that includes feline lower urinary tract disease, urolithiasis, and trauma. A 12-year-old cat with hematuria has a list that includes neoplasia, urolithiasis, and chronic kidney disease. The presenting sign remains the same, but the signalment shifts the probability ranking. The correct answer in a NAVLE question is the one that respects both the signalment and the presenting sign, not the one that ignores either. ## Recognized Failure Modes and Early Detection Signalment-based filtering fails in predictable patterns. The most common failure is anchoring: a student identifies one high-probability breed or species diagnosis and stops generating alternatives. This converts a probability modifier into a certainty filter. Detect this early by forcing a minimum of three differentials before evaluating any single candidate, regardless of how strongly the signalment points to one disease. A second failure mode is overfitting to breed predisposition when the presenting sign is weakly correlated with the predisposed disease. A young Labrador Retriever with acute vomiting is more likely to have dietary indiscretion than hereditary myopathy, even though the breed list for myopathy is shorter. The discriminating check is whether the presenting sign matches the typical clinical course of the predisposed condition, also whether the breed appears on a predisposition list. The third failure mode is temporal neglect. Signalment filters the differential list at a single moment, but many diseases have age windows that shift with management changes. Feline hypertrophic cardiomyopathy can present at 6 months or 14 years. A breed-based filter that excludes the diagnosis outside a narrow age band will miss both ends of the distribution. The corrective action is to treat age as a probability curve, not a binary gate. ## Common Errors and Corrective Actions Students frequently confuse species susceptibility with species exclusivity. Toxicity from lilies is often framed as a feline-only problem, but the clinical question may ask about the dog exposed to the same plant, where the differential priority shifts to gastrointestinal irritation instead of renal failure. The corrective action is to ask what the lesion or toxin does in this species, not what the species is known for. A related error is applying production-animal reasoning to companion animals and the reverse. Rumen acidosis is a high-priority differential in a feedlot steer with anorexia, but it is irrelevant in a pet goat evaluated for the same sign. The [MSD Veterinary Manual professional edition](https://www.msdvetmanual.com/) organizes many conditions by production class precisely because the same species can have different disease spectra depending on use. Students should identify the production class before applying species-based filters. A third error is ignoring reproductive status when it is the strongest signalment variable. A intact female dog with polyuria and polydipsia has pyometra high on the list even when the presenting sign is not classically reproductive. The corrective action is to check reproductive status before finalising any differential list for a middle-aged intact female, regardless of the body system involved. ## Limitations of Evidence and Divergent Expert Opinion The evidence base for breed predisposition is uneven. Some conditions have robust multi-institutional data, while others rest on case series or single-center reports. The [ICVA NAVLE candidate information](https://www.icva.net/navle/) describes the examination as testing clinical reasoning across species, but it does not specify which breed associations the examination considers established. This creates genuine uncertainty: a student may encounter a breed-disease pairing that is widely taught but thinly documented. Expert opinion diverges most on how heavily to weight breed when the presenting sign is common and the predisposed disease is rare. Some clinicians argue that breed should only break ties between otherwise plausible differentials. Others apply breed as an early filter that can eliminate candidates. The safer approach for examination purposes is to keep the predisposed condition on the list but rank it below more common causes of the same sign, unless the signalment match is extreme and the clinical picture aligns. Regional variation compounds this problem. A disease that is common in one practice area may be exotic in another, and breed popularity shifts geographically. The [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) address reportable diseases that must be considered regardless of local prevalence, which creates a separate filter layer that can override breed-based reasoning entirely. ## Referral, Consultation, and Reporting Triggers Signalment-based reasoning should trigger escalation when the filtered list contains a disease with public health, regulatory, or zoonotic implications. Rabies, brucellosis, and highly pathogenic avian influenza are examples where the signalment may point to a common condition, but the possibility of a reportable disease requires diagnostic testing before or alongside routine care. The [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) define which conditions require notification, and the [AVMA practice resources](https://www.avma.org/resources-tools) provide guidance on state and federal reporting obligations in the United States. Students should know that reporting obligations override client confidentiality and practice autonomy. Referral is warranted when the filtered differential list includes a condition requiring advanced imaging, specialised endoscopy, or surgical expertise that the primary setting cannot provide. A breed-predisposed cardiac disease with an ambiguous echocardiogram, or a suspected portosystemic shunt in a breed where the condition is common, should prompt referral before initiating empirical therapy that could obscure the diagnosis. Laboratory involvement is indicated when the signalment-filtered list includes diseases with overlapping biochemical profiles. A young cat with icterus and anemia requires differentiation between hemolysis and hepatic disease, which may require coagulation panels, blood smears, and bile acid testing. The decision to escalate should be made when the physical examination and minimum database cannot separate the top three filtered differentials. ## Troubleshooting Table | Observation | Likely Cause | Discriminating Check | |---|---|---| | One differential dominates the list | Anchoring on breed or species predisposition | Generate three alternatives before evaluation | | Breed match but atypical clinical course | Overfitting to predisposition | Compare onset, progression, and lesion distribution to the classic description | | Age-appropriate disease excluded | Temporal neglect | Recheck the full age range for the predisposed condition | | Species susceptibility applied across species | Species exclusivity confusion | Ask what the disease or toxin does in this species | | Production class ignored | Cross-context reasoning | Identify use class before applying species filters | | Reproductive status not considered | Signalment omission | Verify intact status before finalising any list | | Reportable disease not on list | Regulatory filter absent | Consult current notifiable disease lists before finalising | | Top differentials cannot be separated | Diagnostic ceiling reached | Escalate to advanced testing or referral | ## Frequently Asked Questions ### How do I rank differentials when the signalment points to a rare disease and the presenting signs point to a common one? Start with the common disease that fits the signalment, then ask whether the rare disease explains findings the common one cannot. A young intact male dog with acute abdominal pain and a palpable prostate is more likely to have benign prostatic hyperplasia than a prostatic abscess, even though the abscess explains fever and sepsis better. The NAVLE rewards prioritizing prevalence within the species and age class, then using atypical features to promote the less common diagnosis. If the rare disease is reportable or carries public health significance, mention it in your answer even when it ranks lower. The [ICVA NAVLE candidate information](https://www.icva.net/navle/) confirms that questions test clinical reasoning across species, so your ranking logic matters more than memorising every rare condition. ### What should I do when the signalment fits two diagnoses equally well? Compare the consequences of missing each diagnosis. A 5 year old female cat with weight loss and vomiting could have chronic kidney disease or lymphoma. Missing lymphoma delays treatment, but missing kidney disease changes fluid therapy decisions immediately. Rank the diagnosis whose misdiagnosis causes the most harm first, then use additional history to separate them. Ask about appetite, water intake, and response to prior treatment. The [MSD Veterinary Manual professional edition](https://www.msdvetmanual.com/) organizes many conditions by species and system, which helps you build a complete list before you rank. When two diagnoses remain tied after full evaluation, state both in your answer and explain the test that would distinguish them. ### How do I adjust my differential list when I cannot run the diagnostic tests I would prefer? Work backwards from the tests you can run. If you only have a chemistry panel and urinalysis, rank differentials by which ones those tests can support or exclude. A 12 year old dog with polyuria and polydipsia can be evaluated for diabetes mellitus, hyperadrenocorticism, and chronic kidney disease with basic testing alone. If you cannot measure cortisol, you can still document urine specific gravity and proteinuria to narrow the list. The [AVMA practice resources](https://www.avma.org/resources-tools) address practical limitations in clinical settings, including financial constraints and equipment availability. In your NAVLE answer, prioritize the diagnosis you can confirm with available tests, but note which additional tests would change your ranking. ### How does my differential list change when the same presenting sign appears in a different species? The list changes more than most students expect. Vomiting in a dog suggests dietary indiscretion, pancreatitis, or foreign body. Vomiting in a horse suggests gastric dilatation, enteritis, or grass sickness depending on region. Vomiting in a cat suggests hairball, inflammatory bowel disease, or lymphoma. The same sign carries different urgency by species. A cow with abdominal distension and no feces has a surgical abdomen until proven otherwise, while a dog with the same signs might have simple constipation. The [WOAH terrestrial animal health standards](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) also remind you that some species-specific signs indicate reportable diseases, which changes both your differential ranking and your legal obligations. ### What records should I keep when I use signalment to prioritize differentials? Record the signalment, the ranked differential list, the reasoning for the ranking, and the tests that would change your decision. This documentation matters for continuity of care and for defending your clinical reasoning later. Write the list before you run tests, then update it with results. Note which differentials you excluded and why. If you deprioritised a disease based on breed or age, record that reasoning explicitly. The [AVMA practice resources](https://www.avma.org/resources-tools) include guidance on medical record keeping standards. In a NAVLE question, you will not keep records, but you should practice articulating your reasoning in writing because the exam rewards clear, defensible logic over vague impressions. ### How do I explain my signalment-based ranking to a client who expects a specific diagnosis? Lead with what you found, then explain why the signalment narrows the possibilities. Say that a young dog is more likely to have an infection than a tumor, or that an older cat is more likely to have chronic disease than a dietary indiscretion. Use plain language for the reasoning, not the full differential list. Clients respond well to hearing that you ranked possibilities by likelihood and that your diagnostic plan tests the most probable causes first. If you need to justify a more expensive test, explain that the signalment makes the less common diagnosis possible and that the test distinguishes it from the more common one. The [MSD Veterinary Manual professional edition](https://www.msdvetmanual.com/) provides client-friendly summaries of common conditions that can help you frame your explanation without oversimplifying the medicine. ## Related Clinical & Scientific Guides * [Developing a Study Schedule for NAVLE Diagnostic Reasoning](/knowledge/veterinary-medicine/navle-exam-prep/developing-a-study-schedule-for-navle-diagnostic-reasoning) * [Veterinary Physiology Concepts Frequently Tested on the NAVLE](/knowledge/veterinary-medicine/navle-exam-prep/veterinary-physiology-concepts-frequently-tested-navle) * [NAVLE Clinical Rotation Preparation: What to Review Before Each Service](/knowledge/veterinary-medicine/navle-exam-prep/navle-clinical-rotation-preparation-what-to-review-before-each-service) ## References and Further Reading - [ICVA NAVLE Candidate Information](https://www.icva.net/navle/). ICVA. - [AAVMC Veterinary Education Resources](https://www.aavmc.org/). AAVMC. - [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual. - [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association. - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). WOAH. ## Related Articles - [Building a Differential Diagnosis List for the NAVLE](/knowledge/veterinary-medicine/navle-exam-prep/building-a-differential-diagnosis-list-for-the-navle) - [Differential Prioritization in Emergency Presentations](/knowledge/veterinary-medicine/navle-exam-prep/differential-prioritization-in-emergency-presentations) - [High-Yield Differential Diagnoses for Common Presenting Signs](/knowledge/veterinary-medicine/navle-exam-prep/high-yield-differential-diagnoses-for-common-presenting-signs) - [Veterinary Immunology Concepts for the NAVLE](/knowledge/veterinary-medicine/navle-exam-prep/veterinary-immunology-concepts-navle) - [Veterinary Pharmacology Calculations for the NAVLE](/knowledge/veterinary-medicine/navle-exam-prep/veterinary-pharmacology-calculations-navle) > This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.