Porcine NAVLE High-Yield Guide: Swine Questions You Must Know

Porcine medicine represents approximately 5 to 7 percent of NAVLE questions, yet it is consistently one of the most under-prepared species categories for companion-animal-focused students. That gap is an opportunity. A focused study of high-yield swine content can meaningfully raise your overall NAVLE score without requiring you to master every nuance of a five-hundred-sow farrow-to-finish operation.

This guide covers exactly what the NAVLE tests: herd-medicine thinking, the most commonly examined porcine diseases, reportable foreign animal diseases, anesthesia hazards unique to pigs, and production-system concepts that appear on swine-focused questions year after year.

The Herd-Medicine Mindset for NAVLE Porcine Questions

The single most important conceptual shift for porcine NAVLE questions is moving from individual-animal medicine to population-level thinking. Unlike a dog or cat presenting to a clinic, swine questions almost always describe a production problem: a percentage of a group affected, an age class with clinical signs, or a herd-level outcome like increased pre-weaning mortality or reduced average daily gain.

When you read a porcine vignette, ask these questions before selecting an answer:

• What age group is affected? (Neonatal, nursery, grow-finish, breeding herd)
• Is the problem reproductive, respiratory, enteric, or neurologic?
• What is the morbidity versus mortality pattern? High morbidity + low mortality suggests a different differential than high morbidity + high mortality.
• Is this a foreign animal disease? Fever plus vesicular lesions in swine demand immediate USDA APHIS reporting.

Treatment in swine is almost always discussed at the group level (in-water or in-feed medication), and cost-effectiveness is a legitimate consideration the NAVLE will test. Recommend euthanasia for severely ill individuals and treat the group, not the reverse.

Top Tested Porcine Diseases: Quick Reference

The table below summarizes the ten most frequently tested porcine conditions on the NAVLE. Memorize the age distribution and key distinguishing signs for each one.

Neonatal and Nursery Enteric Disease

Diarrhea is the most common clinical problem in young pigs and accounts for a significant portion of pre-weaning mortality. The NAVLE will ask you to differentiate between several enteric pathogens based on age at onset, character of diarrhea, and mortality pattern.

Porcine Epidemic Diarrhea (PED)

PED virus is an alpha-coronavirus that causes devastating outbreaks in naive herds. In piglets less than one week of age, mortality approaches 100 percent. The diarrhea is voluminous, watery, and yellow. Vomiting may precede diarrhea. Older pigs develop profuse diarrhea but typically survive. PED is a reportable disease in the United States and must be reported to state veterinarians and USDA APHIS. There is no specific antiviral treatment; feedback (controlled exposure of pregnant sows to intestinal contents of affected piglets) is used to stimulate lactogenic immunity.

Transmissible Gastroenteritis (TGE)

TGE virus is also a coronavirus and is clinically almost identical to PED in neonates. The key distinguishing feature for the NAVLE is age distribution: TGE causes high mortality in piglets under two weeks, but pigs over three weeks of age have substantially lower mortality. The villi of the small intestine are destroyed, causing malabsorption and osmotic diarrhea. TGE has decreased in prevalence since the emergence of PED in the United States.

Rotavirus

Porcine rotavirus (Groups A, B, C) causes diarrhea primarily in piglets one to four weeks of age. Mortality is lower than with PED or TGE. Rotavirus is a common co-infection with other enteric pathogens. Vaccination of sows provides passive immunity via colostrum.

Escherichia coli

Enterotoxigenic E. coli causes neonatal diarrhea (within the first week of life) and post-weaning diarrhea (PWD). Edema disease, caused by Shiga toxin-producing E. coli (STEC), occurs in the first few weeks after weaning, presenting with sudden death, ataxia, and subcutaneous edema (especially periorbital). Treatment includes oral electrolyte replacement and antimicrobials. Vaccination of sows with E. coli bacterin reduces neonatal losses.

Porcine Respiratory Disease Complex (PRDC)

Porcine Respiratory Disease Complex (PRDC) is the most economically important respiratory syndrome in swine worldwide. It is a multifactorial condition caused by a combination of viral and bacterial pathogens acting together with environmental and management stressors. The NAVLE tests your ability to identify the individual pathogens and their specific roles.

PRRSV deserves special emphasis: it is the most economically important swine pathogen in North America. It is an enveloped single-stranded RNA virus (Arterivirus family). The "blue ear disease" name originated in Europe due to cyanosis of ear tips in severely affected sows. There is no curative treatment. Herd stabilization via modified-live virus (MLV) vaccination and strategic herd closure are the primary control tools.

Reproductive Disease and the SMEDI Syndrome

Reproductive failure in swine is assessed on the NAVLE through the SMEDI syndrome: Stillbirths, Mummies, Embryonic Deaths, and Infertility. The three most commonly tested causes are PRRSV, Porcine Parvovirus (PPV), and Leptospirosis.

PRRSV Reproductive Syndrome

In the breeding herd, PRRSV causes late-term abortions, increased stillbirths and mummies, weak-born pigs, and reproductive failure in gilts. The clinical pattern often involves a sudden increase in premature farrowings and an associated respiratory disease outbreak in the nursery simultaneously.

Porcine Parvovirus (PPV)

Porcine parvovirus is the classic cause of SMEDI in non-immune gilts. PPV infects the fetus transplacentally. If exposure occurs before 35 days of gestation, embryonic death and resorption result in small litters or return to estrus. Exposure between days 35 and 70 results in mummies. After day 70, fetuses mount an immune response and survive. Vaccination of gilts before first breeding is highly effective and routinely done.

Leptospirosis

Leptospira interrogans serovars (particularly Pomona and Bratislava) cause late-term abortions, stillbirths, and infertility. Treatment is with streptomycin or penicillin. Vaccination (multivalent bacterins) and rodent control are cornerstones of prevention.

Lameness and Musculoskeletal Disease

Lameness questions in swine most commonly center on Glasser's disease, erysipelas, osteochondrosis dissecans in boars, and MMA syndrome in sows.

Glasser's Disease

Glaesserella parasuis (formerly Haemophilus parasuis) causes polyserositis in nursery pigs typically four to eight weeks of age. The hallmark pathological finding is fibrinous peritonitis, pericarditis, and pleuritis on necropsy — "paint brush" fibrin deposits on serosal surfaces. Joints may be swollen. Treatment is penicillin; bacterin vaccination of sows provides passive immunity.

Erysipelas

Erysipelothrix rhusiopathiae causes three clinical forms: (1) acute septicemia with high fever and sudden death, (2) subacute form with characteristic diamond skin lesions (urticarial plaques on the skin), and (3) chronic form with vegetative endocarditis and non-erosive arthritis. The drug of choice is penicillin. Erysipelas is a zoonotic disease — veterinarians and abattoir workers can develop erysipeloid (localized skin infection) after exposure. Vaccination is effective and widely used.

Osteochondrosis Dissecans (OCD)

OCD is a developmental orthopedic disease occurring most commonly in rapidly growing boars and gilts. Genetic selection for rapid lean growth has increased prevalence. The stifle, elbow, and hock are common sites. Affected animals show progressive lameness; early culling is typically recommended.

MMA Syndrome

Mastitis-Metritis-Agalactia (MMA), also called farrowing fever or postpartum dysgalactia syndrome, affects sows within 12 to 24 hours after farrowing. The triad is fever, reduced milk production (agalactia), and uterine discharge. E. coli is the most commonly implicated pathogen. Treatment includes oxytocin to stimulate milk letdown, broad-spectrum antibiotics, and anti-inflammatory drugs. Untreated MMA leads to severe piglet starvation.

Nutrition and Metabolic Disease

Iron Deficiency Anemia

Piglets are born with minimal iron stores and sow's milk is a poor source of iron. Without supplementation, piglets develop hypochromic microcytic anemia by two to three weeks of age — pale skin, poor growth, and increased susceptibility to infection. Prevention is simple and highly effective: injectable iron dextran (100–200 mg IM) on days 1 to 3 of life. This is one of the most standard swine husbandry procedures and a favorite NAVLE teaching point.

Mulberry Heart Disease (Vitamin E / Selenium Deficiency)

Mulberry heart disease is caused by vitamin E and/or selenium deficiency. It affects rapidly growing pigs, typically two to four months old, and presents as sudden death or acute cardiovascular collapse. The characteristic gross pathology is a mottled, hemorrhagic myocardium resembling a mulberry. Skeletal muscle lesions (nutritional muscular dystrophy) may coexist. Treatment and prevention: selenium and vitamin E supplementation. Be aware that selenium toxicity (blind staggers) is also tested — the therapeutic window is narrow.

Salt Toxicity (Water Deprivation Encephalopathy)

Salt toxicity in pigs classically occurs after a period of water deprivation followed by sudden unrestricted access to water. Pigs are particularly susceptible because they are often managed in groups with a limited number of water access points. The pathophysiology involves sodium accumulation in the brain during deprivation, and the subsequent rapid drop in serum sodium during rewatering causes osmotic swelling of neurons. Clinical signs mimic polioencephalomalacia: aimless wandering, head pressing, seizures, and blindness. Histologically, eosinophilic infiltrates (eosinophilic meningoencephalitis) are characteristic. Critical management point: do NOT rewater severely deprived pigs rapidly — reintroduce water slowly in small amounts over 24 to 48 hours to prevent worsening cerebral edema.

Zoonoses and Reportable Diseases in Swine

This section is extremely high yield. The NAVLE tests your knowledge of which swine diseases require immediate regulatory notification and which are zoonotic hazards for veterinary personnel. Knowing these is non-negotiable.

For FMD and ASF, the NAVLE expects you to recognize the clinical presentation AND know the correct regulatory action: immediately quarantine the premises and contact USDA APHIS. Do not attempt to treat. Do not move animals. Do not wait for laboratory confirmation to report.

Anesthesia and Handling in Pigs: Malignant Hyperthermia

Porcine anesthesia questions almost always involve one concept: malignant hyperthermia (MH).

Malignant hyperthermia is a pharmacogenetic disorder caused by a mutation in the ryanodine receptor gene (RYR1), historically called the halothane gene or porcine stress syndrome (PSS) gene. The mutation is autosomal recessive and is most prevalent in Pietrain and Landrace breeds selected for high lean muscle mass.

The condition is triggered by:

• Inhalant anesthetics, particularly halothane
• Succinylcholine (depolarizing neuromuscular blocker)
• Physical and psychological stress (handling, transport, mixing with unfamiliar pigs)

Clinical signs develop rapidly: sustained muscle rigidity, rapidly escalating hyperthermia, tachycardia, hypercapnia, and metabolic acidosis. Death occurs within minutes if untreated. Sudden death in stressed pigs at slaughter (pale, soft, exudative pork — PSE) is also a manifestation of this syndrome.

Treatment: dantrolene sodium (inhibits RYR1-mediated calcium release from the sarcoplasmic reticulum), immediate cessation of triggering agent, active cooling, and correction of acidosis. Dantrolene can also be given pre-operatively for prophylaxis in susceptible breeds.

For routine porcine anesthesia on the NAVLE, remember:

• Ketamine + xylazine is a common injectable combination for minor procedures
• Isoflurane (not halothane) is the preferred inhalant when gas anesthesia is required
• Pigs are prone to stress-induced hyperthermia and respiratory compromise; minimize handling time and avoid hot environments
• Atropine is useful for managing bradycardia and hypersalivation

Biosecurity and APHIS Reportable Disease Protocol

The NAVLE will present scenarios requiring you to identify both the likely diagnosis and the appropriate regulatory response. For swine, the key biosecurity and reporting principles are:

• All-in / all-out (AIAO) management by room or barn is the cornerstone of swine biosecurity. It breaks the cycle of pathogen transmission between age groups.
• Quarantine new arrivals for a minimum of 30 days. Acclimation to herd pathogens (especially PRRSV and M. hyopneumoniae) before introduction to the main herd is critical.
• Shower-in / shower-out facilities at the biosecurity perimeter are standard in high-health commercial herds.
• For any vesicular disease (suspect FMD, SVD, VS), the protocol is: stop all animal movement, quarantine premises immediately, contact state veterinarian and USDA APHIS emergency hotline. Do not attempt to confirm with in-clinic diagnostics first.
• For ASF or CSF, the same immediate reporting obligation applies. The US has national response plans for both.
• Permit requirements for interstate transport of swine and the role of the National Swine Identification System may appear in regulatory-type questions.

From First Login to Passing Day: A Porcine Study Plan

Related NAVLE Study Resources

Porcine medicine does not exist in isolation on the NAVLE. These related guides provide essential context and cross-species comparison that will strengthen your overall performance:

• The Complete NAVLE Study Guide — full exam blueprint, scoring, and strategy for all species
• NAVLE Species Breakdown — how many questions to expect per species and where to focus study time
• Bovine NAVLE High-Yield Guide — cattle share many herd-medicine principles with swine; this guide reinforces production-animal thinking
• How to Pass the NAVLE on Your First Try — study planning, test-taking strategy, and timing tips from veterinarians who have been there

Frequently Asked Questions: Porcine NAVLE Questions