NAVLE Mnemonics: 12 Memory Tricks for Vet Students

Building a complete differential list

“DAMNIT-V”

1. DDegenerative
2. AAnomalous (congenital)
3. MMetabolic
4. NNeoplastic, Nutritional
5. IInflammatory, Infectious, Immune-mediated, Idiopathic
6. TToxic, Traumatic
7. VVascular

Use it when: Neurology stems (seizures, paresis, vestibular signs) and any 'which is the most likely cause' item where you need to make sure the right category is on your list.

Careful: DAMNIT-V checks completeness, not likelihood. Rank by signalment and time course: peracute and non-progressive suggests vascular or trauma; chronic and progressive suggests degenerative or neoplastic. Idiopathic epilepsy is a diagnosis of exclusion, typically in dogs aged about 6 months to 6 years.

Causes of hypercalcemia

“GOSH DARN IT”

1. GGranulomatous disease (systemic fungal infection, e.g. blastomycosis)
2. OOsteolytic lesions (bone tumors, multiple myeloma)
3. SSpurious: lipemia, hemolysis, young growing animals
4. HHyperparathyroidism (primary)
5. DVitamin D toxicosis: cholecalciferol rodenticides, calcipotriene psoriasis creams
6. AAddison's disease (hypoadrenocorticism)
7. RRenal failure
8. NNeoplasia: humoral hypercalcemia of malignancy (lymphoma, anal sac adenocarcinoma)
9. IIdiopathic (mainly cats)
10. TTemperature (hypothermia)

Use it when: Stems with a high calcium on a chemistry panel: pick the next diagnostic (ionized calcium, PTH, PTHrP, rectal exam, lymph node aspirate) or the most likely cause for the signalment.

Careful: Confirm with ionized calcium first: renal failure often raises total calcium while ionized calcium is normal or low. In dogs, neoplasia (especially lymphoma) is the most common pathologic cause, so do a rectal exam for anal sac masses and palpate the lymph nodes. In cats, idiopathic hypercalcemia leads the list.

Organophosphate and carbamate toxicosis (muscarinic signs)

“SLUDGE”

1. SSalivation
2. LLacrimation
3. UUrination
4. DDefecation (diarrhea)
5. GGI distress
6. EEmesis

Use it when: Toxicology vignettes with excess secretions, miosis and bradycardia after insecticide exposure, and items asking for the antidote.

Careful: Atropine controls only the muscarinic signs; muscle tremors, weakness and paralysis are nicotinic. Pralidoxime (2-PAM) helps organophosphates if given before the enzyme bond 'ages', but not carbamates. Do not confuse with permethrin toxicosis in cats, which causes tremors and seizures without SLUDGE and is treated with methocarbamol, bathing and intravenous lipid.

Rodenticides by mechanism

“K for Klotting, B for Brain, C for Calcium, Z for gas”

1. KAnticoagulants (brodifacoum, bromadiolone and others): vitamin K antagonists causing delayed bleeding; antidote vitamin K1
2. BBromethalin: cerebral edema with tremors, seizures or paralysis; no antidote, so decontamination and supportive care
3. CCholecalciferol: hypercalcemia and hyperphosphatemia leading to acute kidney injury; fluids, furosemide, prednisone, bisphosphonates
4. ZZinc phosphide: releases phosphine gas in the acid stomach; vomitus is a hazard to staff, so ventilate the room

Use it when: Stems where a pet ate 'rat bait' and you must choose the right test, monitoring plan or treatment.

Careful: Bait color and brand do not identify the active ingredient; ask for the package or EPA registration number. With anticoagulants, PT prolongs first (factor VII has the shortest half-life) and bleeding starts days after ingestion, so a normal PT on day 1 does not rule it out. Recheck PT 48-72 hours after the last vitamin K1 dose.

Blood color in ruminant poisonings

“Chocolate-brown is nitrate, cherry-red is cyanide”

1. BrownNitrate/nitrite (heavily fertilized forage, weeds, water): methemoglobinemia; treat with methylene blue
2. RedCyanide (wilted Prunus leaves, young sorghum and Johnsongrass): tissues cannot use oxygen, so venous blood stays bright red; treat with sodium nitrite and sodium thiosulfate

Use it when: Herd-death or field-necropsy stems that mention blood color, and items asking which antidote to give.

Careful: Red maple leaf poisoning in horses also causes methemoglobinemia, but with Heinz body hemolysis, and methylene blue is not effective in horses. Acetaminophen in cats causes methemoglobinemia too; the antidote there is N-acetylcysteine.

Bovine respiratory disease complex agents

“I'm Pretty Bad Breathing; My Pal Has Mycoplasma”

1. IIBR (bovine herpesvirus 1)
2. PPI3 (parainfluenza 3)
3. BBVDV (bovine viral diarrhea virus)
4. BBRSV (bovine respiratory syncytial virus)
5. MMannheimia haemolytica: the main cause of shipping fever pneumonia
6. PPasteurella multocida
7. HHistophilus somni
8. MMycoplasma bovis

Use it when: Feedlot and stocker-calf vignettes, vaccine-program items, and questions about which pathogen fits a necropsy finding such as fibrinous pleuropneumonia.

Careful: Modified-live IBR and BVDV vaccines can cause abortion in pregnant cattle unless the label allows use in pregnant cows. BVDV infection of the fetus at roughly days 40-125 of gestation can produce persistently infected calves that shed for life. M. bovis does not respond to beta-lactams because it lacks a cell wall.

Circling ruminant: listeriosis or polio?

“Listeria is lopsided; polio is blind”

Listeriosis is a brainstem disease: one-sided cranial nerve deficits (V, VII, VIII), head tilt, circling toward the lesion, drooling or food packed in the cheek, with normal vision. It is linked to poor silage and treated with high-dose penicillin or oxytetracycline. Polioencephalomalacia is a cortical disease: both eyes blind with intact pupillary reflexes, dorsomedial strabismus, head pressing and opisthotonos, linked to grain diets, high sulfur or thiaminase. It is treated with thiamine.

Use it when: Small ruminant and cattle neurology stems where both conditions appear in the options.

Careful: Lead poisoning also causes central blindness in cattle (especially calves) and is a close mimic of polio; check the history for batteries or old paint and measure blood lead. Give thiamine anyway, because it is part of lead treatment too. Do not let circling alone decide it; vision and symmetry decide it.

Newborn foal milestones

“1-2-3 rule”

1. 1Foal stands within 1 hour
2. 2Foal nurses within 2 hours
3. 3Mare passes the placenta within 3 hours

Use it when: Foaling and neonatal stems that ask whether the timeline is normal and when to intervene.

Careful: Retained fetal membranes (beyond about 3 hours) are an emergency in the mare because of metritis, sepsis and laminitis; do not pull them out forcibly. A foal that misses its milestones is at risk of failure of passive transfer: check IgG at 12-24 hours (over 800 mg/dL is adequate).

Reading test results (sensitivity and specificity)

“SnNout and SpPin”

1. SnNoutA highly Sensitive test with a Negative result rules a disease OUT
2. SpPinA highly Specific test with a Positive result rules a disease IN

Use it when: Epidemiology items on screening versus confirmatory testing, and stems that ask what to do after an unexpected positive or negative result.

Careful: Predictive values depend on prevalence, which the shortcut ignores. In a low-prevalence population, even a good screening test produces many false positives, so a positive FeLV snap test in a low-risk cat should be confirmed with a different test (PCR or IFA) before acting on it.

Rabies exposure management (2016 NASPHV Compendium)

“10, 45, 4”

1. 1010-day observation of a healthy dog, cat or ferret that bites a person
2. 4545-day owner observation for a vaccinated dog or cat exposed to a rabid animal, after an immediate booster
3. 44-month strict quarantine (or euthanasia) for an unvaccinated dog or cat exposed to a rabid animal, with rabies vaccination given immediately

Use it when: Public health stems about a bite to a person or a pet's exposure to a rabid or suspect wild animal.

Careful: The 10-day observation applies regardless of the biting pet's vaccination status, and wildlife or livestock that bite are handled differently (testing, not observation). Dogs and cats that are overdue but have documented prior vaccination are boosted and observed for 45 days. State and local law overrides the Compendium, so the right first step in a stem is often to contact public health authorities.

Drugs prohibited from extralabel use in food animals (21 CFR 530.41)

“Can Cows Drink Nasty Nitro? Few Good Scientists Prescribe Ceph”

1. CChloramphenicol
2. CClenbuterol
3. DDiethylstilbestrol (DES)
4. NNitroimidazoles (dimetridazole, ipronidazole, others)
5. NNitrofurans (furazolidone, nitrofurazone)
6. FFluoroquinolones
7. GGlycopeptides (e.g. vancomycin)
8. SSulfonamides in lactating dairy cattle, except the approved uses of sulfadimethoxine, sulfabromomethazine and sulfaethoxypyridazine
9. PPhenylbutazone in female dairy cattle 20 months of age or older
10. CCephalosporins (not cephapirin) in cattle, swine, chickens or turkeys for prevention, at unapproved doses, frequencies, durations or routes, or in unapproved species or production classes

Use it when: Items on what you may legally prescribe off-label in a food animal, withdrawal times, and antimicrobial stewardship.

Careful: Some of these drugs are legal on label: enrofloxacin and danofloxacin are approved for bovine respiratory disease in beef and non-lactating dairy cattle, and ceftiofur is approved in cattle and swine. What is banned is extralabel use. Extralabel use in feed is not allowed either, and adamantanes and neuraminidase inhibitors are separately prohibited for influenza A in chickens, turkeys and ducks.

Core vaccines for dogs, cats and horses

“Every core list ends in R for rabies”

1. DogDistemper, adenovirus-2, parvovirus, rabies, and Leptospira (AAHA made lepto core for dogs in its 2024 update)
2. CatPanleukopenia (FPV), herpesvirus-1 (FHV-1), calicivirus (FCV), rabies; FeLV is core for cats under 1 year
3. HorseTetanus, Eastern and Western equine encephalomyelitis, West Nile virus, rabies (AAEP)

Use it when: Wellness and herd-health stems that ask which vaccine is core or what to recommend for a new puppy, kitten or horse.

Careful: Leptospirosis was non-core in older guidelines, so older study material is out of date. Canine parainfluenza is usually in the combination product, but AAHA lists it as optional rather than strictly core. Horses that are wounded or have surgery 6 months or more after their last tetanus booster get a tetanus toxoid booster at that time.