What is Parvo?
Parvo is a common and potentially serious viral disease in dogs. The virus is officially known Parvovirus. The disease caused by this virus is commonly referred to as Parvo. The virus first appeared clinically in 1978, and there was a widespread epidemic in dogs of all ages. Since no dogs had been exposed or vaccinated (the vaccine didn't exist at the time), dogs of all ages died from the infection. The virus can "adapt" over time, and other strains of the virus have appeared since then, but properly administered vaccinations are the best protection. Canine Parvovirus is thought to be a mutation from the feline Parvovirus, also known as Feline Distemper virus.
What are the signs seen with Parvovirus infection?
There are three main manifestations of Parvovirus infection:
- Asymptomatic - No signs seen. Common in dogs over 1 year old and vaccinated dogs.
- Cardiac - This form of the disease is much less common than the intestinal form due to widespread vaccination. Severe inflammation and necrosis (cell death), of the heart muscle causes breathing difficulty and death in very young (less than 8 weeks of age) puppies. Older dogs that survive this form have scarring in the heart muscle.
- Intestinal - This virus causes extreme damage to the intestinal tract, causing sloughing of the cells that line the tract. This can leave the patient open to secondary bacterial infection. Most of the affected dogs (85%) are less than one year old and between 6-20 weeks old -- before the full set of vaccinations can be given. The death rate from infection is reported to be 16-35% in this age group.*
The intestinal signs include:
- Loss of appetite
- Diarrhea - usually bloody, and very foul-smelling (a characteristic odor, particular to Parvovirus infection)
- Intussusception - when a section of the inflamed intestinal tract telescopes into itself. This is an emergency.
The onset of clinical signs is usually sudden, often 12 hours or less. The incubation from exposure to seeing the clinical signs varies from 3 to 10 days.
How is Parvovirus infection diagnosed?
This disease is diagnosed by physical examination, signalment (age, vaccination status, breed, etc.), and a fecal Parvo (ELISA) test. Additional diagnostics include blood work and radiographs. Dogs infected with Parvo typically have a low white count. Radiographs help rule out other potential causes for vomiting and diarrhea.
* Stats from The Merck Veterinary Manual, 8th ed.