Canine parvovirus infection

Dr Sunil Bhardwaj
Two types of parvoviruses infect dogs. Canine parvovirus- (COV-1), also known as “minute virus of canines is a relatively non- pathogenic virus that sometimes is associated with gastroenteritis, pneumonitis, and/or myocarditis in puppies 1 to 3 weeks old. Canine parvovirus-2 (CP V-2) is responsible for classic parvoviral enteritis, and there are at least three strains (CPV-2 a, b and c). CPV-2 usually causes signs 5 to 12 days after the dog is infected via the faeco-oral route, and it preferentially invades and destroys rapidly dividing cells (i.e., bone marrow progenitors, intestinal crypt epithelium.)
Clinical Features
The virus has mutated since it was first recognised, and the most recently recognised mutations may be more pathogenic in some dogs. CPV-2b and the even more recently identified CPV-2c can also infect cats. Clinical signs depend on the virulence of the virus size of the inoculum , host’s defences ,age of the pup, and presence of other enteric pathogens (e.g., parasites). Doberman ,Pinschers, Rottweilers, Pit Bulls, Labrador Retrievers, and German Shepherds may be more susceptible than other breeds. Viral destruction of intestinal crypts may produce villus collapse, diarrhoea, vomiting, intestinal bleeding, and subsequent bacterial invasion, but some animals have mild or even subclinical disease.
Many dogs are initially presented because of depression, anorexia, and/or vomiting (which resembles foreign object ingestion without diarrhoea. Diarrhoea is often absent for the first 24 to 48 hours of illness and may not be bloody if and when it does occur, Intestinal protein loss may occur secondary to inflammation, causing hypoalbuminemia. Vomiting is usually prominent and may be severe enough to mimic foreign body ingestion / eosophagitis, damage to bone marrow progenitors may produce transient or prolonged neutropenia, making the animal susceptible to serious bacterial infection, especially if a damaged intestinal tract allows bacterial translocation across the mucosa. Fever and/or SIRS are common in severely ill dogs but are often absent in less severely affected animals. Puppies that are infected in utero or before 8 weeks of age may develop myocarditis.
Rarely, parvoviral infection may be associated with ervthymatous cutaneous lesions.
Diagnosis is often tentatively made based on history and physical examination findings. Neutropenia is suggestive but neither sensitive nor specific for canine parvovirus enteritis; salmonellosis or any overwhelming infection can cause similar leukogram changes. Regardless of whether diarrhoea occurs, infected dogs shed large numbers of viral particles in the feaces (i.e., >10° particles/g). Electron microscopic evaluation of feaces detects the presence of the virus, but CPV-1 (usually non-pathogenic except in neonates) is morphologically indistinguishable from CPV-2. ELISA for CPV-2 in the feaces is typically the best diagnostic test (can be performed in house) and detects both CPV-2b and CPV-2c. Other diagnostic approaches involved PCR , virus hybridisation etc.
Treatment is same as for any severe acute infectious enteritis.
Rigrous fluid and electrolyte therapy , antibiotics, anti emetics, antacids , antihelmintics and nutritional therapy.
Deworming of a pup should be done as early as two weeks of age .
Vaccination should be done as early as one month old pup and its booster dose after 21 days of first shot.
Keep your pup in muzzle when ever taken out . Avoid feeding complex foods in a routine manner and spices
(The author is Veterinary Assistant Surgeon CVH Jammu)