GIT MCQ (3)

Bovine Viral Enteritis

• Rotavirus: Common cause of calf diarrhea, affects villi of the small intestine, typically seen in calves 1-2 weeks old
• Coronavirus: Common cause of calf diarrhea, affects villi of the small intestine, typically seen in calves less than 3 weeks old
• Pestivirus (BVD): Highly contagious, causes high morbidity and mortality, characterized by fever, diarrhea, pneumonia
• Rinderpest: Highly contagious, causes high morbidity and mortality, characterized by high fever, anorexia, decreased milk yield, nasal/ocular mucopurulent discharge, severe bloody diarrhea, dehydration, shock, death
  • Gross Findings: Focal erosions and ulcers of upper GI tract, hemorrhagic, necrotic, edematous Peyer's patches, hemorrhage and congestion of cecum, colon, rectum
  • Microscopic Findings: Lymphoid necrosis, necrosis of intestinal crypts, syncytia, intracytoplasmic and intranuclear inclusion bodies
  • Differential Diagnosis for gastrointestinal ulceration in bovines:
    • Bovine viral diarrhea/mucosal disease: Linear esophageal ulcers
    • Malignant catarrhal fever: conjunctivitis and corneal edema, necrotizing vasculitis
    • Infectious bovine rhinotracheitis: eosinophilic intranuclear inclusions
    • Foot-and-mouth disease: vesicles, affects coronary bands and interdigital areas
    • Bluetongue disease
  • Differential Diagnosis for diarrhea in bovines:
    • Salmonella sp.
    • Johne's disease
    • Coccidiosis
  • Comparative Pathology: Other morbilliviral diseases include:
    • Peste-des-petits-ruminants
    • Canine distemper
    • Measles
    • Phocine distemper
• Malignant Catarrhal Fever (MCF): Causes conjunctivitis and corneal edema, necrotizing vasculitis

Salmonella sp.

• An important zoonosis worldwide
• Transmitted via fecal-oral route
• Disease forms: Septicemic, Acute Enteric, Chronic Enteric
• Most animals are symptomless carriers
• Stressors and/or diseases that compromise immune competence or disrupt the enteric bacterial ecosystem are often implicated in salmonellosis
• Cattle: Commonly seen in newborn calves (usually more than one week old)
  • Gross Findings: Fibrinonecrotic (diphtheritic) enteritis, fibrinous cholecystitis, multifocal hepatitis (paratyphoid nodules)

Enterotoxemia

• Caused by Clostridium perfringens
• Characterized by sudden death in well-nourished animals, necrotizing/hemorrhagic enterocolitis & toxemia
• Gram-positive, sporulating, anaerobic bacillus
• 5 strains (A-E) based on production of 4 major lethal exotoxins (alpha, beta, epsilon, and iota)
• Epsilon toxin (ETX) is the third most potent clostridial toxin (after botulinum and tetanus toxins)
• Types of Clostridium perfringens:
  • A: alpha toxin, Yellow lamb disease
  • B: alpha toxin, beta toxin, and epsilon toxin, Lamb dysentery
  • C: alpha toxin and beta toxin, Bloody diarrhea in neonates, Struck in adults
  • D: alpha toxin and epsilon toxin, Pulpy kidney disease in lambs

Ovine

• Bluetongue: A non-contagious viral disease transmitted by Culicoides, Reoviridae family, orbivirus genus, sheep are most susceptible species, goats and cattle are susceptible
  • Gross Findings: Ulcerations and crust of the skin, mucosa of oral and nasal cavity, edema and cyanosis of the tongue, laminitis and coronitis, hemorrhage in the tunica media at the base of the pulmonary artery
  • Other manifestations: Congenital anomalies (Hydranencephaly), abortion
  • Comparative Pathology: Other common Orbiviruses include:
    • African horse sickness virus
• Peste des Petits Ruminants (PPR): A viral disease (Morbillivirus) of goats and sheep characterized by oculonasal discharge, pneumonia (bronchointerstitial), syncytia, stomatitis, linear hemorrhages, diarrhea

Feline

• Feline Panleukopenia: Caused by parvovirus, affects young cats, rapidly dividing cells in intestine, bone marrow & lymphoid organs
  • Gross Findings: Crypt necrosis & loss, villous atrophy, hyperemia and hemorrhage of intestinal wall, intranuclear inclusions, cerebellar hypoplasia
• Feline Infectious Peritonitis: Caused by mutated enteric Coronavirus infection, multisystemic disease, 2 forms: Wet (effusive) and Dry (pyogranulomas)
  • Gross Findings: Serofibrinous peritonitis & pleuritis, multiple white nodules (pyogranulomas) on the serosal surface of the small intestine

Canine

• Canine Parvovirus Enteritis (CPV-2): Similar to feline disease, interstitial myocarditis in puppies (rare)
• Canine Distemper: Morbillivirus, causes enteritis, encephalitis, pneumonia

Colibacillosis

• Gram-negative bacteria
• Non-virulant strains are considered normal flora
• Most common cause of neonatal diarrhea in calves and pigs
• Enterotoxigenic E. coli: Ingestion of virulent bacteria > adherence to small intestinal enterocytes > toxin production > diarrhea
  • Diarrhea in neonatal pigs, calves, lambs. 2500 serovars/serotypes.
  • Nomenclature: (e.g. Salmonella enterica subsp enterica serotype Typhimurium) (shortened to Salmonella Typhimurium)
  • Highly host-adapted serotypes (e.g. Dublin in cattle, S.Cholerasuis in swine) cause systemic disease (septicemia) in all ages of animal
  • Non host adapted (S.Typhimurium) cause enterocolitis (young animals)
  • Serotypes that invade enterocytes have the ability to survive and replicate within macrophages.