Having a pet that is sick is always heartbreaking and difficult, but it's always worse when they are a young puppy or kitten. Ronin, a 9-week old Red Heeler (Australian Cattle Dog) and Dooley an 8-week old Retriever Mix both came to us lethargic and not eating. After diagnostics were run, both were found to have Parvovirus. Parvovirus is a potentially fatal disease, especially in young puppies.
Parvovirus was first discovered in the 1970s. The virus is spread between dogs through an oral-fecal route, where a dog is exposed to contaminated feces that the parvovirus is being shed in. Parvovirus is a hardy virus that can persist for many years in the environment. It is difficult to inactivate the virus with common disinfectants and detergents.
Once the virus enters the dog, the virus begins to replicate in rapidly dividing tissues (lymph nodes, thymus, intestines, bone marrow, and heart). Clinical signs appear within 1-5 days after exposure to the virus. As the virus destroys the intestinal lining, the dog presents with vomiting and diarrhea. Due to the loss of the intestinal lining, electrolytes are lost resulting in dehydration and the bacteria from the intestinal tract can be released into circulation causing sepsis. As the virus attacks the bone marrow, there is suppression in the white blood cells produced, resulting in the dog not having an immune system to mount a response to the bacteria being released from the damaged intestinal lining and viral infection. Typically the heart muscle is targeted in dogs 8 weeks or younger, resulting in a myocarditis leading to congestive heart failure and death in most cases. The congestive heart failure can occur within days or months after the heart was affected.
Parvovirus is diagnosed based on clinical signs and diagnostics. A positive ELISA test for the viral antigen in the feces confirms the diagnosis of canine parvovirus. A false negative on the ELISA test can be obtained if the test is performed before the virus is shed in the feces. It can take 3-5 days before the virus is shed in the feces after exposure. A complete blood count is performed to assess the bone marrow for any suppression, and to help with the prognosis for the patient. A chemistry panel is performed to assess the electrolytes and organ function.
Only supportive treatment is available for parvovirus infections. The patient is placed on intravenous fluid therapy to correct the dehydration from the vomiting and diarrhea. Electrolytes are supplemented in the intravenous fluids if there is a derangement noted on the chemistry panel. Intravenous antibiotics are given to help prevent or treat sepsis, especially if there is suppression of the bone marrow present. Antiemetic drugs are used to treat the vomiting and nausea associated with the parvovirus infection. The white blood cell count and electrolytes are monitored while the patient is in the hospital to assess response to treatment. Hospital treatment continues until the patient is able to eat without vomiting and their immune system has mounted a response to the virus, in order for treatment with oral medications to commence. The patient will continue to shed the virus in their feces for 7-14 days after recovering.
Parvovirus can be prevented with proper vaccination. A puppy should start the initial vaccine series at 8 weeks of age, and continue to receive vaccines every 3-4 weeks until 16 weeks of age. Puppies are still susceptible to parvovirus infections while undergoing vaccines. Therefore, while puppies are undergoing vaccination they should not be exposed to areas where dogs congregate or pass through with unknown vaccines histories, and to areas where previous parvovirus infected pets have had access.
Thankfully both Ronin and Dooley have recovered nicely and are enjoying life once again with their families. Please be sure your dogs, young and old, are vaccinated against this nasty virus!