This study guide covers medicine for porcine (swine), avian (poultry and pet birds), and exotic companion animals (rabbits, ferrets, reptiles, and small mammals).
Overview and Clinical Importance
This study guide covers medicine for porcine (swine), avian (poultry and pet birds), and exotic companion animals (rabbits, ferrets, reptiles, and small mammals). These species represent important segments of veterinary practice in production medicine, backyard farming, and companion animal care.
High-YieldDomain 4 (Medicine) is the LARGEST BCSE domain with 50-55 questions (approximately 25% of the exam). Understanding species-specific diseases, their pathophysiology, diagnosis, and treatment is essential for exam success.
BCSE Relevance: Questions frequently test knowledge of economically important diseases in food animals, zoonotic concerns, and unique physiological considerations of exotic species that affect diagnosis and treatment.
| Feature |
Details |
| Etiology |
PRRS virus (PRRSV) - RNA virus, Arteriviridae family. Two species: PRRSV-1 (European) and PRRSV-2 (North American) |
| Transmission |
Direct contact with infected pigs, contaminated semen, aerosol (up to 9 km reported), fomites (needles, boots, vehicles), insects (mosquitoes, flies) |
| Clinical Signs - Reproductive |
Late-term abortions, mummified fetuses, stillbirths, weak-born piglets, increased preweaning mortality, irregular estrus return |
| Clinical Signs - Respiratory |
Dyspnea, coughing, pneumonia in growing pigs, slow growth, increased susceptibility to secondary infections |
| Diagnosis |
PCR (gold standard for acute cases), serology (ELISA for herd screening), virus isolation |
| Treatment/Control |
No effective treatment; MLV vaccines reduce clinical signs but do not prevent infection; herd closure and exposure programs; biosecurity |
| Feature |
Details |
| Etiology |
Porcine epidemic diarrhea virus (PEDV) - Alphacoronavirus, similar to TGE virus but no cross-immunity |
| Clinical Signs |
Profuse watery diarrhea, vomiting, dehydration, anorexia. Neonates: up to 100% mortality in piglets less than 7-10 days old |
| Pathophysiology |
Virus destroys villous enterocytes causing villous atrophy, leading to malabsorptive diarrhea |
| Diagnosis |
PCR of feces or intestinal contents, immunohistochemistry on intestinal tissue |
| Control |
Feedback protocols (exposing gilts to infected material), vaccination, strict biosecurity, environmental decontamination |
| Feature |
Details |
| Etiology |
African swine fever virus (ASFV) - large DNA virus, family Asfarviridae. Only DNA virus transmitted by arthropods |
| Transmission |
Direct contact, soft ticks (Ornithodoros), contaminated pork products, fomites. Survives months in cured meats |
| Clinical Signs - Acute |
High fever (40-42 degrees C), hemorrhages (skin, lymph nodes, kidney, GI), cyanotic ears, sudden death, mortality up to 100% |
| Diagnosis |
PCR, virus isolation, ELISA for antibodies - performed ONLY at approved laboratories |
| Control |
NO vaccine available (unlike CSF). Immediate reporting, quarantine, depopulation, movement restrictions |
SECTION 1: PORCINE (SWINE) MEDICINE
Swine medicine encompasses both production animal health and disease surveillance for foreign animal diseases. The US swine industry produces over 120 million pigs annually, making disease prevention and early detection critical for both animal welfare and economic stability.
MEMORY AID - "PRRS PED ASF" - The Big Three: Remember the three most economically devastating swine diseases: PRRS (reproductive/respiratory), PED (enteric), ASF (foreign animal disease). These represent the greatest threats to US swine production.
Porcine Reproductive and Respiratory Syndrome (PRRS)
PRRS is one of the most economically significant diseases in the global swine industry, first recognized in the US in 1987. It is caused by a virus in the family Arteriviridae.
High-YieldPRRS costs the US swine industry approximately $664 million annually. The virus targets macrophages, particularly alveolar macrophages, leading to immunosuppression.
MEMORY AID - "SMAWS" for PRRS Effects: Stillbirths, Mummification, Abortions, Weak piglets, Slow growth - key reproductive and production impacts of PRRS.
[Include Image: Figure 1. Lung lesions in PRRS-affected pig showing interstitial pneumonia]
Source: CDC Public Health Image Library (phil.cdc.gov) or Wikimedia Commons - search "swine pneumonia pathology"
Porcine Epidemic Diarrhea (PED)
PED is caused by a coronavirus (PEDV) and causes severe watery diarrhea, particularly devastating in neonatal piglets. The disease emerged in the US in 2013 and caused massive losses.
High-YieldPED and TGE (Transmissible Gastroenteritis) look clinically identical but do NOT provide cross-protective immunity. Always differentiate with PCR testing.
African Swine Fever (ASF)
ASF is a FOREIGN ANIMAL DISEASE not currently present in the continental US. It is reportable to state and federal authorities. Recognition and immediate reporting are critical.
High-YieldASF is NOT related to Classical Swine Fever (CSF/Hog Cholera) despite similar names. ASF is caused by a DNA virus (Asfarviridae), while CSF is caused by an RNA virus (Flaviviridae). Both are foreign animal diseases in the US.
MEMORY AID - "ASF Has NO Cure" Mnemonic: A = Always reportable, S = Soft tick vector (Ornithodoros), F = Fatal (high mortality), Has NO = No vaccine, NO treatment, NO cross-immunity with CSF.
[Include Image: Figure 2. Hemorrhagic lymph nodes in African swine fever - characteristic "marble" appearance]
Source: FAO (Food and Agriculture Organization) public domain resources or USDA APHIS public images
Other Important Porcine Diseases
Porcine Circovirus Associated Disease (PCVAD)
Caused by Porcine Circovirus Type 2 (PCV2). Results in postweaning multisystemic wasting syndrome (PMWS), porcine dermatitis and nephropathy syndrome (PDNS), and reproductive failure.
MEMORY AID - "PCV2 Wastes Pigs Away": PCV2 causes wasting in post-weaned pigs (PMWS). Key signs: progressive weight loss, enlarged lymph nodes, respiratory distress, jaundice, diarrhea.
Swine Influenza
High-YieldSwine are "mixing vessels" for influenza viruses because they have receptors for both avian and mammalian influenza strains, allowing viral reassortment.
| Feature |
Details |
| Etiology |
Influenza A virus subtypes H1N1, H1N2, H3N2 most common in swine |
| Clinical Signs |
Sudden onset fever, anorexia, lethargy, coughing, dyspnea, nasal discharge. High morbidity, low mortality |
| Zoonotic Potential |
YES - bidirectional transmission between pigs and humans. 2009 H1N1 pandemic originated from swine-origin reassortant virus |
| Control |
Vaccination, biosecurity, all-in/all-out production, avoid mixing pigs from different sources |
| Feature |
Details |
| Etiology |
Influenza A virus, Type A, subtypes H5 and H7 most concerning. Classified as LPAI or HPAI based on pathogenicity in chickens |
| Reservoir |
Wild waterfowl (ducks, geese) and shorebirds - often asymptomatic carriers |
| Clinical Signs - HPAI |
Sudden high mortality, swollen cyanotic head/wattles/comb, hemorrhages, respiratory distress, decreased egg production, neurologic signs |
| Diagnosis |
Virus isolation, RT-PCR, pathotyping (IVPI testing) at approved laboratories only |
| Control |
REPORTABLE DISEASE - immediate depopulation, quarantine, surveillance zones, movement restrictions. Vaccination allowed in some countries |
| Feature |
Details |
| Pathotypes |
Velogenic (viscerotropic or neurotropic) = highly virulent. Mesogenic = moderate. Lentogenic = mild, used in vaccines |
| Clinical Signs - Velogenic |
Respiratory distress, greenish diarrhea, neurologic signs (torticollis, paralysis), sudden death, edematous head, up to 100% mortality |
| Gross Lesions |
Hemorrhages in proventriculus, intestinal hemorrhages (especially at cecal tonsils), splenomegaly |
| Diagnosis |
Virus isolation, RT-PCR, pathotype determination (ICPI greater than 0.7 = virulent) |
| Zoonotic |
Mild conjunctivitis in humans - occupational hazard for poultry workers |
SECTION 2: AVIAN MEDICINE
Avian medicine covers both commercial poultry (chickens, turkeys, ducks) and companion/pet birds (psittacines, passerines). Understanding reportable diseases and zoonotic concerns is critical.
MEMORY AID - "HPAI and vND = High Mortality": Highly Pathogenic Avian Influenza (HPAI) and virulent Newcastle Disease (vND) cause rapid, high mortality in poultry. Both are REPORTABLE and require immediate notification to authorities.
Highly Pathogenic Avian Influenza (HPAI)
High-YieldHPAI H5N1 has caused human deaths and is a significant zoonotic concern. Veterinarians should use appropriate PPE when investigating suspicious mortality events in poultry.
[Include Image: Figure 3. Cyanotic comb and facial swelling in chicken with highly pathogenic avian influenza]
Source: USDA APHIS public images or FAO animal health resources
Newcastle Disease
Newcastle disease (ND) is caused by avian paramyxovirus type 1 (APMV-1). Virulent strains (velogenic) cause devastating disease with high mortality, while mild strains (lentogenic) are used in vaccines.
MEMORY AID - "Newcastle = Neuro + Respiratory + GI": Velogenic Newcastle causes signs in three systems: Neurologic (torticollis, paralysis), Respiratory (gasping), and GI (green diarrhea). Remember: "The NRG of Newcastle" - it affects Neuro, Respiratory, GI.
Marek's Disease
MEMORY AID - "Marek's Makes young birds lame": Marek's disease causes leg paralysis in YOUNG birds (12-24 weeks). Contrast with Lymphoid Leukosis which affects OLDER birds (greater than 14 weeks, usually greater than 4 months). Marek's = paralysis + tumors in young birds.
High-YieldThe classic "splits" position (one leg forward, one back) is characteristic of Marek's disease affecting the sciatic nerve. Affected birds often cannot walk but remain bright and alert.
[Include Image: Figure 4. Chicken with Marek's disease showing characteristic leg paralysis (splits position)]
Source: Wikimedia Commons - search "Marek's disease" or USDA public domain poultry images
Other Important Avian Diseases
MEMORY AID - "BCSE Poultry Pathogens = VIM + NC": Viral: Influenza, Infectious bronchitis, ILT, Marek's, Newcastle, Fowl pox. Bacterial: Mycoplasma, Pasteurella (fowl cholera). Parasitic: Coccidiosis (Eimeria).
| Feature |
Details |
| Etiology |
Gallid alphaherpesvirus 2 (Marek's disease virus - MDV), a highly contagious oncogenic herpesvirus |
| Transmission |
Inhalation of virus shed from feather follicles (dander). Highly stable in environment |
| Clinical Forms |
Classical (neural) - leg paralysis from sciatic nerve involvement. Acute (visceral) - lymphomas in liver, spleen, gonads, kidneys. Cutaneous - feather follicle tumors. Ocular - irregular pupil, blindness |
| Key Age Group |
Usually affects birds 12-24 weeks of age (younger than lymphoid leukosis) |
| Control |
VACCINATION at day-old or in ovo. HVT (herpesvirus of turkeys) vaccine most common. Vaccine prevents tumors but NOT infection |
| Disease |
Etiology |
Key Features |
Control |
| Infectious Bronchitis |
Coronavirus (IBV) |
Respiratory signs, egg production drop, wrinkled eggs, nephritis in some strains |
Vaccination, biosecurity |
| Infectious Laryngotracheitis (ILT) |
Gallid alphaherpesvirus 1 |
Severe dyspnea, blood-tinged mucus, high mortality |
Vaccination (attenuated or recombinant) |
| Fowl Pox |
Avipoxvirus |
Dry form (skin nodules) or wet form (diphtheritic membranes in mouth/trachea) |
Vaccination, mosquito control |
| Coccidiosis |
Eimeria species |
Bloody diarrhea (E. tenella - cecal), weight loss, high morbidity |
Anticoccidials in feed, vaccination, litter management |
| Mycoplasma gallisepticum |
Mycoplasma gallisepticum |
Chronic respiratory disease, sinusitis, egg production drop |
Eradication, antibiotic treatment, vaccination |
| Feature |
Details |
| Definition |
Slowing or cessation of normal GI motility, often leading to cecal dysbiosis |
| Causes |
Low fiber diet, dehydration, pain (dental disease, other illness), stress, lack of exercise, intestinal obstruction |
| Clinical Signs |
Anorexia, decreased/absent fecal pellets, hunched posture, teeth grinding (bruxism - sign of pain), abdominal distension |
| Diagnosis |
History, physical exam, radiographs (gas distension, foreign body rule-out) |
| Treatment |
Fluid therapy, prokinetics (metoclopramide, cisapride), pain management, syringe feeding critical care formula, hay/fiber once eating |
SECTION 3: EXOTIC ANIMAL MEDICINE
Exotic companion animals include rabbits, ferrets, guinea pigs, chinchillas, hamsters, rats, reptiles, and amphibians. These species have unique anatomical and physiological features that affect disease presentation and treatment.
High-YieldExotic species often hide signs of illness until disease is advanced. Additionally, many drugs are used off-label with limited pharmacokinetic data. Species-specific dosing and husbandry corrections are essential.
Rabbit Medicine
Rabbits are hindgut fermenters with unique digestive physiology. They are obligate nasal breathers and are extremely sensitive to stress. Common conditions include GI stasis, dental disease, pasteurellosis, and encephalitozoonosis.
Gastrointestinal Stasis
MEMORY AID - "Rabbit GI Stasis = FHPS": Fiber deficiency, Hairball/obstruction, Pain, Stress - the four major causes of rabbit GI stasis. Treatment priority: Fluids, Pain relief, Prokinetics, Syringe feeding.
High-YieldRabbits cannot vomit due to a well-developed cardiac sphincter. Never attempt to induce vomiting in rabbits. True GI obstruction is a surgical emergency.
Encephalitozoonosis
Encephalitozoon cuniculi is a microsporidian parasite causing neurologic, renal, and ocular disease in rabbits. It is zoonotic and particularly concerning for immunocompromised humans.
MEMORY AID - "E. cuniculi Hits Head, Eyes, Kidneys": The three target organs: Head (neurologic/vestibular), Eyes (phacoclastic uveitis), Kidneys (chronic nephritis). Remember: "HEK" = Head, Eyes, Kidneys.
[Include Image: Figure 5. Rabbit with head tilt (torticollis) due to vestibular disease]
Source: Wikimedia Commons - search "rabbit head tilt" or veterinary education open access resources
Pasteurellosis (Snuffles)
Pasteurella multocida is a common commensal in rabbit nasal passages but can cause clinical disease when immunity is compromised. It affects multiple body systems.
High-YieldRabbit abscesses contain thick, caseous pus that does not drain well. Treatment usually requires complete surgical excision rather than lancing and draining. Long-term antibiotic therapy is often needed.
Ferret Medicine
Ferrets are obligate carnivores with high metabolic rates and short GI transit times. Common conditions include adrenal disease, insulinoma, and lymphoma - the "big three" of ferret medicine.
MEMORY AID - "Ferrets Get AIL": The three most common ferret diseases: Adrenal disease, Insulinoma, Lymphoma. All are very common in middle-aged to older ferrets (greater than 3 years).
High-YieldFerrets require rabies and canine distemper vaccination. Both diseases are fatal in ferrets. Use ONLY approved ferret vaccines to avoid anaphylaxis.
[Include Image: Figure 6. Ferret with adrenal disease showing symmetric truncal alopecia]
Source: Veterinary education resources or Wikimedia Commons
Reptile Medicine
Reptiles are ectothermic with unique physiological requirements. Most reptile diseases are related to improper husbandry (temperature, humidity, UV lighting, diet). Metabolic bone disease is extremely common in captive reptiles.
Metabolic Bone Disease (MBD)
MEMORY AID - "MBD = Missing UV-B Diet calcium": The two main causes of MBD: Missing UVB lighting and Missing dietary calcium. Always ask about UV light source and diet when presented with a weak reptile.
High-YieldDifferent reptile species have different UVB requirements. Diurnal lizards (bearded dragons, iguanas) need high UVB. Nocturnal species need less but still benefit from UVB access. All require appropriate temperature gradients for proper metabolism.
Other Common Reptile Conditions
MEMORY AID - "Reptile Problems = TEMPS": Temperature wrong, Environment inadequate, Metabolic (MBD), Poor diet, Stress - the five husbandry factors behind most reptile diseases.
Porcine Medicine Key Points
- PRRS is the most economically significant endemic swine disease - causes reproductive failure and respiratory disease
- PED causes severe diarrhea with up to 100% mortality in neonatal piglets - virus destroys intestinal villi
- ASF is a foreign animal disease with NO vaccine - immediate reporting required
- Swine are "mixing vessels" for influenza - zoonotic concern
Avian Medicine Key Points
- HPAI and vND are reportable diseases causing high mortality - immediate notification required
- Marek's disease causes paralysis and tumors in young birds (12-24 weeks) - vaccination prevents tumors but not infection
- Wild waterfowl are natural reservoirs for avian influenza
Exotic Animal Medicine Key Points
- Rabbits: GI stasis is common and potentially fatal - fiber deficiency, pain, and stress are main causes
- E. cuniculi causes head tilt, renal disease, and phacoclastic uveitis in rabbits - zoonotic
- Ferrets: Adrenal disease, insulinoma, and lymphoma are the "big three" diseases
- Reptiles: Most diseases are husbandry-related - always assess UVB, temperature, and diet
- MBD in reptiles results from calcium deficiency and/or lack of UVB exposure
| Feature |
Details |
| Clinical Signs - Neurologic |
Head tilt (torticollis), vestibular disease, nystagmus, ataxia, rolling, seizures, hind limb paresis |
| Clinical Signs - Renal |
Chronic kidney disease, polyuria/polydipsia, weight loss (often subclinical) |
| Clinical Signs - Ocular |
Phacoclastic uveitis from lens rupture (typically unilateral), cataracts |
| Diagnosis |
Serology (IgG/IgM - exposure, not necessarily active disease), PCR of urine, definitive diagnosis requires histopathology |
| Treatment |
Fenbendazole (20 mg/kg PO q24h for 28 days), supportive care, anti-inflammatories. Treatment may not reverse existing damage |
| Manifestation |
Clinical Features |
| Upper Respiratory (Snuffles) |
Mucopurulent nasal discharge, sneezing, matted fur on front paws from wiping nose |
| Lower Respiratory |
Pneumonia, dyspnea, anorexia, cyanosis |
| Otitis Media/Interna |
Head tilt (peripheral vestibular - differentiate from E. cuniculi) |
| Abscesses |
Subcutaneous abscesses with thick, caseous pus that does not drain well |
| Genital |
Pyometra, orchitis, metritis |
| Disease |
Clinical Signs |
Diagnosis/Treatment |
| Adrenal Disease |
Bilateral symmetric alopecia (starting at tail), vulvar swelling in spayed females, prostate enlargement in males (stranguria), pruritus |
Dx: Clinical signs, ultrasound, hormone panel. Tx: Surgery (adrenalectomy), GnRH agonists (deslorelin implant), melatonin |
| Insulinoma |
Episodic weakness, ataxia, ptyalism (drooling), pawing at mouth, seizures, hypoglycemia (blood glucose less than 70 mg/dL) |
Dx: Fasting blood glucose less than 60 mg/dL, elevated insulin. Tx: Frequent small meals, prednisone, diazoxide, surgery |
| Lymphoma |
Peripheral lymphadenopathy, splenomegaly, weight loss, weakness. May be classic, mediastinal, or GI form |
Dx: FNA/biopsy of lymph nodes, CBC, imaging. Tx: Chemotherapy (prednisone plus other agents), supportive care |
| Feature |
Details |
| Definition |
Group of disorders resulting in weakened bones due to calcium/phosphorus imbalance, usually from nutritional deficiency or lack of UVB |
| Causes |
Inadequate calcium in diet, improper Ca:P ratio (should be 2:1), lack of UVB lighting (prevents vitamin D3 synthesis), renal disease |
| Clinical Signs |
Soft/pliable mandible (rubber jaw), limb tremors, pathologic fractures, kyphosis/lordosis, anorexia, weakness, egg binding in females |
| Diagnosis |
History (husbandry review essential), physical exam, radiographs (decreased bone density, fractures), blood calcium/ionized calcium |
| Treatment |
Correct husbandry (proper UVB, temperature), calcium supplementation (oral or injectable), supportive care, address underlying cause |
| Condition |
Species Affected |
Key Features |
| Respiratory Infection |
All species, especially chelonians and snakes |
Open-mouth breathing, nasal discharge, wheezing. Often caused by improper temperature/humidity. Bacterial, viral (paramyxovirus), or fungal |
| Dystocia (Egg Binding) |
All egg-laying species |
Inability to pass eggs. Causes: MBD, improper nesting site, oversized eggs. Emergency requires oxytocin or surgery |
| Stomatitis (Mouth Rot) |
Snakes, lizards |
Caseous material in mouth, petechiae, swelling. Often secondary to immunosuppression from poor husbandry |
| Inclusion Body Disease |
Boid snakes (boas, pythons) |
Neurologic signs, regurgitation, respiratory disease. Caused by arenavirus. Fatal, no treatment |
| Shell Rot |
Chelonians (turtles/tortoises) |
Ulcerative shell disease from bacteria/fungi. Often from poor water quality or trauma. Requires debridement and antibiotics |