Viral infection in canines: prevention and cure


Our doggies too suffer from dreaded viral infections. One of the highly contagious viral diseases is caused by Canine Parvovirus-2. Here’s how to prevent, diagnose and treat it.
What is parvovirus gastroenteritis?
Canine Parvovirus gastroenteritis is a viral infection caused by Canine Parvovirus-2 (CPV-2) in dogs. It is a serious and highly contagious viral disease that occurs in carnivorous animals with dog as a principal host. The disease mainly affects gastrointestinal tract and heart of the dogs depending upon the age of the affected dog.
Dogs at risk
Generally dog of any age and sex can be affected by CPV-2 infection. Some breeds including Doberman Pinschers, Rottweilers, American Pit Bull Terriers and German Shepherds are more predisposed to the disease than other dogs. But most severe form of the disease is observed in puppies of less than three months of age. Adult dogs are comparatively resistant to CPV-2 infection and develop only mild syndrome.
Transmission in dogs
The CPV-2 is very stable in environment and resistant to most of common disinfectants. The virus is transmitted to susceptible dogs by direct contact with the infected dog. Virus is also transmitted indirectly through contamination of the fomites, food by feces of infected dogs. The virus is shed in feces by infected dogs for at least three weeks after infection.
Signs of Parvovirus gastroenteritis
CPV-2 has affinity towards actively dividing cells in host body. So, virus attacks the actively dividing cells of the body which includes bone marrow, lymphoid tissue, intestinal epithelium and myocardial cells in puppies less than three month of age. Affected dogs show dullness, anorexia, fever, vomiting and diarrhoea. The gastroenteritis is more severe in young pups below 20 weeks of age. The clinical disease is exaggerated by concurrent infection with opportunistic intestinal pathogens like Salmonella, Clostridium perfringens, E. coli, Campylobacter, Coronavirus or worms.
The feces are loose and may contain mucus or in severe cases blood (melena). Fluid loss causes rapid dehydration and electrolyte and acid-base imbalance in young dogs. Affection of villous epithelium is also responsible for decrease in absorption of food. Affection of bone marrow causes reduction in white blood cells of body which might further increase susceptibility of dogs to a number of other infections. If appropriate treatment and care is provided, chances of recovery and survival increase. Occasionally affection of myocardium by virus may lead to congestive heart failure and pulmonary edema in pups less than three months old, finally culminating in death.
Diagnosis of Parvovirus gastroenteritis
Generally history of vaccination and clinical signs tell us about the Parvovirus gastroenteritis. Blood tinged diarrhoea and vomitng in unvaccinated but dewormed dogs give suspicion about CPV-2 infection. Laboratory tests like haemagglutination test, enzyme linked immunosorbent assay (ELISA) to detect Parvovirus antigens in fecal sample of dogs are most commonly used for diagnosis of CPV-2 infection in dogs. Complete blood count and biochemical parameters will further tell about physical condition as well as outcome of the disease.
Treatment of Parvovirus gastroenteritis
There is no treatment as such for Parvovirus gastroenteritis. But timely supportive cares save life of dogs affected with CPV-2. In severe cases, signs of circulatory collapse blood transfusion or plasma expanders are indicated. Before transfusion of blood compatibility testing should be done with donor blood. But most commonly, fluid and electrolyte therapy remains as a mainstay of treatment of CPV-2 infection. Lactated Ringers solution and Dextrose is given intravenously to compensate fluid and electrolyte losses.
As affected dog is immunosuppressed, broad spectrum antibiotic coverage with bactericidal drug is required to check any secondary bacterial infection that might otherwise further aggravate the condition. Feeding and watering is commonly withheld till subsidence of vomition. While recovering, dog should be offered with bland diet containing rice, cottage cheese or commercially available prescription diet with gradual inclusion of normal diet should be given based on the speed of recovery.
Preventing Canine Parvovirus infection in your dogs
Premises of dogs should be kept clean with disinfectants like household bleach (1:30 dilution), formalin, gluteraldehyde, etc. Canine Parvovirus infection of dogs can be prevented totally by vaccinating your dog against CPV-2 infection at right time. But sometimes maternal antibodies which provide passive protection against CPV-2 infection may interfere with development of post vaccination immunity. The exact time of disappearance of maternal antibodies from pup is not known. So, vaccination of pups should be started at age of 6-8 weeks and continued at interval of four weeks till 14-16 weeks of age. This will help in inducing very good level of active immunity in pups against CPV-2 infection. Thereafter every year annual booster vaccination should be given.
Until your pups attend the age of 16 weeks with history of complete vaccination against CPV-2, care should be taken to prevent contact with feces of other puppies or dogs if you are taking your dogs for walk in parks and gardens. Modified live virus vaccines are most commonly available in the market for CPV-2 infections. The vaccines available in India for Parvovirus infection include single vaccines like Duramune KF-II, Megavac-P (both live and inactivated vaccine), Nobivac-Parvo-C, Parvocin, Vanguard-CPV and combined vaccines like Megavac-6, Nobivac-DHPPi, Nobivac-DH-LR, etc.
Although CPV-2 is one of serious infections of dog’s especially young pups, it can be prevented by maintaining proper hygiene and vaccinating pups at right age.
The authors are PhD scholars at Division of Medicine, Indian Veterinary Research Institute (IVRI), Izatnagar, Bareilly, UP.