Canine & Feline Parvo

Question 1

What is the structure of viruses in the family Parvoviridae?

Answer 1

• 5kb ssDNA
• Noneveloped
  *

Question 2

How stable are parvo viruses?

Answer 2

• Highly resistant to disinfection/temperature/pH
• Infectious for months to years

Question 3

How do parvo viruses replicate in the host?

Answer 3

• Occurs in cells with high mitotic rates
  
  • No viral DNA polymerase
  • Requires host nucleoprotein synthesis (DNA replication)
• Primary sitesL
  
  • tissues undergoing organogenesis in fetal or neonatal development
  • Enteric epithelial crypt cells, hematopoietic and lymphoid tissues

Question 4

What is Canine Parvovirus (CPV-2)?

Answer 4

• 1978 - now present worldwide
• Infects dogs, coyotes, wolves, foxes, raccoons, sknks
• 3 main variants ( 2a, 2b, 2c)
  
  • similar virulence
  • 2b - most commonly associated with illness
  • 2c - most recent emergence

Question 5

How is CPV-2 transmitted?

Answer 5

• Direct: oronasal contact with infectious feces
• Indirect: oronasal contact with contaminated fomites
  
  • environment, personnel, equipment
  • D

Question 6

When do infected dogs start shedding the CPV-2 virus?

Answer 6

• 4-5 dpi
  
  • can occur prior to clinical onset of disease
• continues up to 10 days after clinical resolution

Question 7

What happens during phase 1 of CPV-2 infection?

Answer 7

• Initial replication in oropharyngeal lymphoid tissue
• Subsequent replication in Peyer’s patches and GI lymphoid tissue

Question 8

What happens during phase 2 of CPV-2 infection?

Answer 8

• Virus spreads by blood and lymphatics to secondary sites of replication
• Targets rapidly dividing cells:
  
  • SI crypt epithelium
  • Bone marrow
  • Primary and secondary lymphopoietic tissue

Question 9

What is the pathogenesis of CPV-2 in the lymphopoietic/hematopoietic cells/tissues, intestinal crypt epithelium, or in utero infection?

Answer 9

• Lymphopoietic/hematopoietic cells/tissues:
  
  • Leukopenia (lymphopenia, neutropenia
  • Immunosuppression
• Intestinal crypt epithelium:
  
  • epithelial necrosis and villus atrophy
  • Impaired absorptive capacity
  • Disrupted gut barrier - bacterial translocation
• In utero / < 8 week sw/out maternal antibodies:
  
  • Myocarditis
  • Myocardial necrosis

Question 10

What are the 2 disease syndromes of CPV-2?

Answer 10

• Myocarditis
• acute enteritis

Question 11

What happens with CPV-2 associated myocarditis?

Answer 11

• Infection in utero or < 8 weeks
• Clinical presentation:
  
  • acute cardiopulmonary failure or delayed, progressive cardiac failure
    
    • +/- enteritis
• Less common
  
  • maternal antibodies from vaccination or exposure are protectie

Question 12

What happens with CPV-2 associated acute enteritis ?

Answer 12

• Most common
• Young puppies (6wk - 6 mo)
  
  • waning maternal antibodies
  • unvaccinated or incomplete vaccination
  • Breed susceptibility: Dobermans, rottweilers, labs, pit bulls
• Co-morbidities affect disease severity
  
  • Elevated stress, poor nutrition, GI parasites, others
• Intussusception can occur

Question 13

What is the clinical presentation of CPV-2 enteritis?

Answer 13

• Clinical signs develop w/in 5-7 dpi and last between 2-14 days
• Early signs can be nonspecific - lethargy, decreased appetite
• Progresses to vomiting and small-bowel diarrhea (often hemorrhagic) w/in 24-48 hrs
• Depression, pyrexia, dehydration, abdominal pain, dilated and fluid-filled intestinal loops
• Septic shock: weak femoral pulse, prolonged CRT, tachycardia, hypothermia, collapse

Question 14

What are the results of a CBC on a CPV-2 infected dog?

Answer 14

• Moderate to severe leukopenia characterized by lymphopenia and neutropenia

Question 15

What are the serum chemistry results associated with CPV-2?

Answer 15

• Prerenal azotemia, hypoalbuminemia (protein loss through GI tract) hyponatremia, hypokalemia, hypochloremia, hypoglycemia, increased liver enzymes

Question 16

What gross necropsy lesions are associated with CPV-2?

Answer 16

• Thickened and discolored intestinal wall
• Watery, mucoid, or hemorrhagic intestinal contents
• Edema and congestion of lymph nodes
• Thymic atrophy

Question 17

What histopathologic lesions are associated with CPV-2?

Answer 17

• Multifocal necrosis of intestinal crypt epithelium
• Intestinal villus blunting and sloughing
• Lymphoid depletion
• Bone Marrow hypoplasia

Question 18

Hos is CPV-2 diagnosed?

Answer 18

• High index of suspicion at presentation:
  
  • young, incomplete or no vaccination, compatible clinical signs
  • may be newly acquired - incomplete medical history
• SNAP test - ELISA for CPV-2 capsid antigen in feces
  
  • Widely available, easy to use, rapid results
  • Detects all subtypes, minimal reactivity with MLVs
  • Good specificity; sensitivity depends on virus shedding
    
    • Test at presentation/onset of clinical illness
    • Negative w/ high index of suspicion should be re-tested in 1-2 days
• Detection of virus/antigen in feces
  
  • PCR, EM, VI
• Detection of CPV-2 antibodies
  
  • 4x increase in IgG titer over 14 day period
  • IgM antibody without recent vaccination (>4wks)

Question 19

What is the treatment for CPV-2?

Answer 19

• Fluid therapy
  
  • lactated ringers or 0.9% saline
  • SQ fluids for mild dehydration (<5%)
  • IV fluids for moderate to sever dehydration
    
    • +/- dextrose and KCl supplementation
    • +/- colloid for sever hypoproteinemia
• Antibiotics
  
  • prevent secondary infection
  • broad-spec w/ good gram negative coverage (enterics)
    
    • ampicillin-sulbactam IV - inpatient
    • Cefovecin - outpatient
• Antiemetics - prolonged/intractable vomiting
• Nutritional support
  
  • small amounts of bland flood when vomiting resolved

Question 20

What is the prognosis of CPV-2?

Answer 20

• W/out treatment:
  
  • death can occur w/in 1-3 days of clinical onset
  • mortality can be >90%
• W/ supportive treatment:
  
  • 70-90% of dogs with enteritis survive
  • most pups that survive the first 3-4 days will recover

Question 21

What biosecurity measures should be taken with CPV-2?

Answer 21

• Limit environment contamination and spread
• Isolate positive patients - separate housing and equipment
  
  • consider moving suspect animals out of the waiting room
• Proper PPE
• Frequent cleaning/disinfection:
  
  • Bleach (1:30), Virkon-S, accelerated hydrogen peroxide

Question 22

What is the CPV-2 vaccine?

Answer 22

• AAHA Core vaccine
• Modified-live vaccine
  
  • initial 6-8wks, 10-12 wks, 14-16 wks
  • Booster 1 year later, then every 3 yrs
• Inactivated vaccine
  
  • pregnant dogs or colostrum deprived pups
• Protective against different subtypes

Question 23

What is Feline Panleukopenia Virus (FPV)?

Answer 23

• “Feline distemper”
• Before 1900
• Worldwide distribution - infrequent due to vaccination
• Causes disease in felids, raccoons, foxes and mink

Question 24

How is FPV transmitted?

Answer 24

• Oronasal exposure - direct or indirect
  
  • virus is abundant in all secretions/excretions during acute phase of illness
• Shedding typically occurs over a short period (1-2 days) but up to 6 wks has been reporterd

Question 25

What is the pathogenesis of FPV in pregnant queens?

Answer 25

• Virus may spread transplacentally
• Embryonic resorption, fetal mummification, abortion/stillbirth

Question 26

What is the pathogenesis of FPV in Perinatal kittens?

Answer 26

• Virus infects the germinal epithelium of the cerebellum (dividing neuroblasts)
• Cerebellar hypoplasia:
  
  • ataxia, tremors, blindness, hypermetric movements
• Syndrome has become rare due to passive maternal antibody transfer

Question 27

What is phase one of FPV infection?

Answer 27

• Initial replication in oropharyngeal lymphoid tissue
• subsequent replication in Peyer’s patches and GI lymphoid tissues

Question 28

What is phase two of FPV infetion?

Answer 28

• Hematogenous spread (viremia) to secondary sites of replication
• Targets rapidly dividing cells:
  
  • SI crypt epithelium
  • Bone Marrow
  • Primary and secondary lymphopoietic tissue
• Viremia usually resolves within 5-7 days due to induction of neutralizing antibodies

Question 29

What is the clinical presentation of FPV?

Answer 29

• Most infections are subclinical
• Clinical disease most common in cats 3-5 months of age
• Disease more common with rescues and groups of unvaccinated cats
• Peracute cases - may die suddenly
• Acute:
  
  • Clinical signs appear within 2-7 dpi, last approx 4-7 days
  • Pyrexia, decreased appetite, depression, +/- transient diarrhea, vomiting, dehydration, +/- abdominal pain, thickened intestinal loops, enlarged mesenteric lymph nodes
  • CBC/chem: similar to CPV-2
  • Septic shock: hypothermia, DIC

Question 30

What are the lesions associated with FPV?

Answer 30

• Dilated intestinal loops with thickened and hyperemic walls
• Petechiae on intestinal serosal surfaces
• Dilated intestinal crypts
• Necrotic intestinal epithelial cells
• Villus blunting and fusion

Question 31

How is FPV diagnosed?

Answer 31

• Presumptive: hx, vaccination status, clinical signs, leukopenia
• Fecal antigen/virus detection
  
  • Rapid ELISA antigen test: false negative possible = short duration of virus shedding
  • PCR - more sensitive
• FPV antibody tests - mainly for retrospective use

Question 32

What is the treatment for FPV?

Answer 32

• Fluid therapy and parental broad-spectrum antibiotics

Question 33

What is the prognosis for cats with FPV?

Answer 33

• Better for cats receiving adequate supportive therapy
  
  • mortality highest in kitten s< 5 month
  • prognosis is poorer with low total WBC (<2,000/uL)
• Cats will be briefly immunosuppressed following FPV infection

Question 34

What is the FPV vaccine?

Answer 34

• AAFP Core Vaccine
• Modified live virus
  
  • begin at 6-9 wks
  • boost every 3-4 weeks until 16-20 wks of ag
  • Booster at 6 months, 1 year, and then every 3 years
• Inactivated vaccines:
  
  • safer for pregnant, immunosuppressed, FIV or FeLV + cats