Hepatobiliary Infectious Diseases

Question 1

describe canine parvovirus-2 (CPV-2)

Answer 1

1. non-enveloped DNA virus: VERY resistant to disinfectants!
   -recommendation is Clorox
2. subfamily: parvovirinae
3. genus: parvovirus
   -includes feline panleukopenia virus (can use SNAP test for feline panleuk)
4. affects dogs and other canidae, but ferrets, mink, and cats have been experimentally infected

Question 2

describe signalment and transmission of CPV-2

Answer 2

1. contaminated feces contacts oral and nasal cavity
   -fomites
   -transplacental also possibke
2. intermittent shedding
   -begins 3 days after onset of signs
   -peak at 4 days
   -gradually reduced at 7 days
   -can affect testing! if not shedding high numbers, SNAP test may not detect so need to dx based on clin signs, suspicion, and history
3. can affect any breed, age, and sex
   -but seen most commonly in puppies 6wk-6mo old

Question 3

describe pathophysiology of CPV-2

Answer 3

1. uptake virus in epithelium over the tonsils
2. replication in lymphocytes in draining LNs
3. dissemination of infected lymphoblasts to thymus, spleen, lymph nodes, and peyer’s patches
4. lymphocytolysis leads to viremia
5. infection of GI crypt epithelium, hematopoeitic precursor cells, and cardiomyocytes (in utero infections)
   -why? these cells have high rates of division that parvo uses the division enzyme to activate itself
6. apoptosis of infected cells

Question 4

describe clinical signs of CPV-2

Answer 4

1. vomiting: GIT inflammation
2. diarrhea: increased permeability and malabsorptive
   -foul smelling, mucoid to melena and/or hematochezia
3. anorexia: feel like shit
4. fever, lethargy: inflammatory cytokines
5. sudden death: secondary to sepsis, DIC

Question 5

describe CPV-2 diagnosis

Answer 5

1. based on history, clinical signs, and a positive SNAP test
   -SNAP test (ELISA): detects antigen, very specific but poor sensitivity, can have false negative based on stage of shedding
2. bloodwork:
   -CBC: leukopenia
   -biochem: hypoproteinemia, hypoalbuminemia, hypoglycemia, prerenal azotemia
3. PCR: can be positive after vaccination!! s false positives are possible

Question 6

describe acute hemorrhagic diarrhea syndrome

Answer 6

1. used to be called hemorrhagic gastroenteritis
2. dx: based on clin features and ruling out other pathogens
3. clostridium perfringens type A
   -gram positive bacillus
   -anaerobic
   -alpha toxin, ENTEROTOXIN, NetE, NetF!!, NetG, others
4. more common in dogs

Question 7

describe C. perf type A signalment and tranmission

Answer 7

1. likely commensal bacterial overgrowth
   - +/- diet change or indiscretion
   -toxigenic strains in both healthy and diarrheic dogs
2. any breed, age, sex
   -middle age (approx 5 yrs) small breeds (approx 9.8kg) more common

Question 8

describe pathophysiology of C. perf type A

Answer 8

1. enterotoxin:
   -pore-forming
   -binds to claudin in epithelial cells leading to increased paracellular permeability
2. NetF:
   -also pore-forming

microscopically: areas of necrosis

Question 9

describe C. perf type A clinical findings

Answer 9

1. vomiting; hematemesis
   -inflammation or necrosis of intestinal mucosa
2. diarrhea: melena or hematochezia
   -inflammation or necrosis of intestinal mucosa
3. anorexia, lethargy: inflammatory cytokines
4. tachycardia: due to hypovolemia by time of presentation
5. chronic GIT dz occurs in 28% of dogs that recovered from AHDS

Question 10

describe diagnosis of C. perf type A

Answer 10

1. hx, clin signs, and exlusion of other pathogens (esp parvo)
2. bloodwork:
   -CBC: neutrophilia with a left shift
   -biochem: hypochloremia, hypokalemia, metabolic acidosis
3. anaerobic culture: presence does NOT mean disease
4. C. perf toxins gene PCR
   -positive does NOT mean toxin production
5. toxin ELISA not practical

Question 11

describe C. perf Type A in foals

Answer 11

1. foal necrotizing enteritis
2. in foals <10d old
   -adequate transfer of passive immunity
3. anorexia, diarrhea, depression, dehydration
   -colic without diarrhea
4. sudden death due to disease, sepsis
   -outbreak or solitary cases both possible