Canine Parvoviral Infection

• It is infectious viral disease of dogs, cat, cattle and human beings.
• It attacks intestinal cells or myocardium.
• Puppies are more susceptible than adult dogs.
• Parvovirus is less likely to affect older dogs because of their immunity through natural infection or immunization.
• Disease is characterized by sudden onset of vomiting, diarrhoea, dysentery, depression, anorexia, pyrexia, severe dehydration, leucopenia and death.

Etiology:

• Parvovirus of Parvoviridae family
• It is small, non-enveloped, single stranded DNA virus with icosahedral symmetry
• It replicates in nuclei of rapidly dividing cells such as lymphoid cells, thymus, intestinal epithelium, bone marrow and heart, forming intracellular inculsion bodies.
• Stable in environment, resistant to heat, solvents, disinfectants and pH changes.

Epidemiology:

• Infection spreads quickly over countries and continents.
• Morbidity rate reaches upto 100% and mortality is upto 10%.
• Young puppies are more susceptible to disease. Breeds like Dobermann and Labrador are at higher risk.
• Virus is highly resistant and persist in the environment for months, making thorough disinfection essential.
• Outbreaks can be more prevalent during dry season.
• In 1978, CPV has rapidly spread worldwide, resulting in outbreaks and high morbidity rates among dog populations.
• CPV has undergone genetic changes, leading to the emergence of different genotypes (CPV-2a, CPV-2b, and CPV-2c), which have expanded its host range to include cats and tissue culture cells.
• virus is more infectious in males than females.

Transmission:

• virus is transmitted through direct contact with infected animal or its excretion.
• Virus are excreted in enormous quantity through feces.
• Virus is highly contagious and spreads directly and indirectly by anything contaminated by fecal materials, fomites, saliva, vomit and urine.

Pathogenesis:

• Virus gains entry through ingestion or intake into skin or oral mucosa; even minimal amount of virus.
• Virus targets tissue of intestinal cells and lymphoid tissue and begins replicating.
• Virus then disseminated to lymph node, bone marrow via blood.
• During this replicative phase, it enters blood stream, leading to viremia.
• Within a few days, it reaches organs characterized by high cellular proliferation rates and continues replicating.
• Canine parvovirus infiltrates the hemopoietic system within the bone marrow, disrupting leukocyte production
• It induces continual cellular sloughing within the intestinal villi, resulting in bloody diarrhea and heightening the risk of secondary bacterial infections as intestinal bacteria enter the bloodstream.
• Most fatalities associated with this virus stem from persistent vomiting and diarrhea, which lead to severe dehydration followed by hypovolemic shock.

Clinical Findings:

• Incubation period is typically 3-7 days.
• Disease is manifested in 2 forms; enteric form and Myocarditic form

1. Enteric form

• It is characterized by high rise of temperature, inappetance, refusal of food, diarrhoea and vomition.
• Diarrheic stool may contain blood.
• Vomitus may contain yellow frothy material or bile colored frothy materials or blood.
• Sudden depression
• Animals pass brownish; semi-solid feces mixed with excess mucus followed by fetid hemorrhagic diarrhea.
• Dehydration and exhaustion due to vomition and diarrhea.
• Death occurs due to peripheral circulatory failure.

2. Myocarditic form:

• Damaged heart muscles and affected animals show signs of circulatory failure.
• Respiratory problem, pulmonary edema
• Depression, cough, ascites
• Animal may die due to cardiogenic shock
• Death occur in susceptible dogs between 4-8 weeks of age.

PM findings:

• Lower and middle small intestine dilated- contents are watery and flocculent
• Bone marrow depleted.
• Lungs heavy and edematous, grey-pink in color with fecal congestion
• Heart dilated with ill defined pale areas in myocardium
• Hemorrhage in pancreas
• Clear watery fluid in thorax and abdomen
• Pale, flabby heart with myocardial fibrosis in more chronic case

Diagnosis:

• Based on the history of vaccination
• Based on clinical findings
• Based on PM findings
• Isolation of virus: viral antigen can be demonstrated in feces
• Hemagglutination test, hemagglutination inhibition test (HI), FAT
• ELISA, Commercial diagnostic kit
• Hematology: Leukopenia due to lymphopenia and granulocytopenia
• Abdominal radiograph: Gas and fluid distension may be evident.
• Serum chemistry profile: Prerenal azotemia (elevation in BUN and creatinine), hypokalemia secondary to anorexia and losses from vomiting and diarrhea, hypoalbuminemia, hypoglycemia

Differential Diagnosis:

1. CDV:

• It affects respiratory system and neurological signs appear.

2. Canine coronavirus:

• Vomiting and diarrhea is mild in corona virus.
• Often seen in kennel cough outbreaks

3. Bacterial Enteritis:

• Fecal culture demonstrates bacteria.

Treatment and Control Measures:

• Immediate isolation of suspected or confirmed cases.
• Supportive therapy is indicated in hospital settings.
• Broad-spectrum antibiotics; Ceftriaxone, Ceftiofur is administered parenterally usually IV; @15-20 mg/kg, b.wt. BID
• SC administration of fluids; D5 or RL
• Parenteral administration of antiemetics; Maropitant @ 1mg/kg, SC every 24 hours
• In the absence of substantial vomiting, oral electrolyte solutions can be offered.
• Correcting dehydration, replacing ongoing fluid losses, and providing maintenance fluid needs are essential for effective treatment.
• Dogs must be monitored for development of hypokalemia and hypoglycemia. supplementation of IV fluids with potassium chloride (supplemented in fluids at 20–40 mEq/L) and dextrose (supplemented in fluids at 2.5–5%) is appropriate if electrolytes and serum blood glucose concentration cannot be routinely monitored.
• For severe clinical signs and/or marked neutropenia, additional gram-negative coverage (eg, enrofloxacin [10–20 mg/kg, IV, every 24 hours for 5–7 days] or gentamicin [9–12 mg/kg, IV, IM, or SC, every 24 hours for 5–7 days]) is indicated.
• Ondansetron @0.5 mg/kg, IV, every 8 hours as needed to control vomiting) appear to be equally effective at controlling vomiting.
• fecal microbiota transplantation (taking 10 g of feces from a healthy dog, then diluting in 10 mL of saline solution [0.9% NaCl] and administering rectally 6–12 hours after admission) in dogs with CPV infection was associated with a faster resolution of diarrhea and shorter hospitalization time.
• Personnel handling dogs with confirmed or suspected parvoviral enteritis must follow strict isolation procedures.
• All surfaces should be cleaned of gross organic matter and then disinfected with a solution of dilute bleach (1:30) or a peroxygen, potassium peroxymonosulfate, or accelerated hydrogen peroxide disinfectant.
• The same solutions may be used as footbaths to disinfect footwear.
• vaccination with a modified live virus vaccine is recommended at 6–8, 10–12, and 14–16 weeks of age, followed by a booster administered 1 year later and then every 3 years.