Parvovirus – An update

By Beth Davidow, DVM DACVECC

ACCES Medical Director

A week ago, we alerted referring veterinarians in the area to an uptick in the number of parvovirus cases we were seeing at ACCES’ two referral hospitals (Seattle and Renton). Word quickly spread to the greater community setting off an unexpected scare.

Parvovirus is a virus that causes vomiting and severe diarrhea. In addition, it can suppress the immune system and put animals at risk for secondary infections. It mainly affects puppies and can cause death if not treated appropriately. With treatment, which includes intravenous fluids, anti-nausea medication, antibiotics and plasma in severe cases, survival is 90%. Adults dogs can get the infection as well but often are less sick or may shed virus and not have clinical signs.

The virus is shed in stool and can live in the environment for weeks to months. It is extremely hardy and not killed by standard disinfectants – bleach is most effective. The virus can be passed from an animal shedding the virus, picked up on clothes, shoes, and other objects, and then carried to another animal.

Parvovirus is not a new infection. It is a virus we have known about for a long time and one of the first diseases for which we developed a vaccine for dogs. The vaccine is extremely effective when administered properly. Puppies need to receive vaccines every three to four weeks from eight weeks of age until they are over 16 weeks of age, again at one year and then every three years thereafter.

The difficulty with this disease is that puppies often get sick in the window after they have had one vaccine but not the full series. If puppies are in environments where the virus has been shed by asymptomatic carriers, they can pick up the virus. Health for the dog population relies on compliance by everyone – a concept known as “herd immunity”.

This year we have seen an uptick in the number of parvo cases. We see an average of 16 cases a year and have diagnosed 28 this year, eight in the last three weeks. The virus does ebb and flow so this may just be a high year. Cases have been from a number of locations and have been mostly young, incompletely vaccinated dogs. However, it is also possible that the move away from vaccines has led to less herd immunity and more shedding of virus. Speaking to other hospitals in the area, some are also seeing more cases but other clinics north of us are not.

Our recommendations are:

1)     VACCINATE – make sure your puppy gets the full SERIES of vaccines up to at least 16 weeks of year. Make sure the vaccine is boostered one year later and then every three years after that.

2)     Do not take incompletely vaccinated puppies to dog parks or other high traffic areas. Dog parks are great places to socialize but only after the full series of puppy shots have been given.

3)     If you have a dog with vomiting and diarrhea, have them seen promptly. Early diagnosis and proper treatment does lead to a good long term outcome.

If your dog is fully vaccinated, there is no reason to avoid the dog parks – let your dogs play if we have a sunny day. 

Parvovirus; Think Outside the Box

By Dr. Beth Guerra

Quite a few years ago, I evaluated a one year old schnauzer for an acute onset of vomiting and diarrhea. He had no known medical problems and had not eaten anything unusual that could have caused his symptoms. The owner allowed me to do a complete workup, including x-rays and bloodwork. There were very few abnormalities except for a very low white blood cell count, which can indicate overwhelming infection or inadequate bone marrow response to infection. I was wracking my brains for a cause that would also explain his symptoms, when I noted in the chart that the owner had acquired him as a very young puppy and that he was not yet neutered.  When I asked why she had not neutered him, she said he had never visited a veterinarian. That set off a bell in my head, and I questioned her about vaccine status. She reported he had never had any vaccines or boosters and that the breeder did not mention that he was given any before she acquired him. I immediately set up a parvo test, and it was a strong positive.

Veterinarians tend to think of parvovirus as a disease of very young puppies, usually under 16 weeks of age. The general public knows of parvo as “the puppy killer” because it is highly contagious and often affects young dogs that are not fully developed and therefore have an immature immune system. What I had failed to think of in this case was that even though this dog was a year old, he had never been vaccinated and therefore was still at risk for contracting the virus. We just had another case present this week with a severe parvo infection who is 4 years old, but again, had not been fully vaccinated.  In our current case, he had a single puppy shot and not the full series needed to produce immunity.

Parvovirus is ubiquitous in the environment and very difficult to kill with normal disinfectants; prolonged contact with a bleach solution is required. It is highly contagious and can remain in the environment for many months. Transmission between animals is via oral exposure to feces containing the virus, however, objects such as bedding and toys can also transmit the virus. Infection can be widespread in environments such as pet stores or breeding facilities due to close contact between animals. Incubation within the body can be up to two weeks and the virus can continue to be shed in the feces after infection has resolved.

The virus targets specialized crypts in the intestinal lining where new cells are rapidly produced. These cells die off and the intestinal lining becomes more permeable, allowing for loss of vital blood proteins and electrolytes and also letting harmful bacteria into the bloodstream from the intestinal tract. 

Symptoms include vomiting, diarrhea (often bloody), inappetance, and abdominal pain. Septic shock or disseminated intravascular coagulation (widespread hemorrhage) can occur in severe cases. The virus can also destroy developing white blood cells. The drop in crucial white cells increases the risk of secondary bacterial infections.

Diagnosis is based on presenting symptoms, vaccine history, and test results, which can include a positive parvo test (fecal test that can be done in house), decreased white blood cell count, or low blood albumin. Some puppies also have intestinal parasites that are found on fecal exam. Therapy is supportive while the virus runs its course. Intravenous fluids, anti-emetics, and broad spectrum antibiotics are utilized to minimize secondary effects of the virus. Some animals receive transfusions of whole blood or plasma. Parvovirus can be rapidly fatal if left untreated and these cases usually require several days of hospitalization on the road to recovery. Puppies that develop severe sepsis or secondary infections, such as pneumonia, may succumb to the disease. However, studies have shown that chance of survival with aggressive treatment is over 90%.

Once infection has cleared, the puppy may have lifelong immunity, however, vaccines are the best prevention. Puppies usually receive a series of “combo” vaccines, which include distemper, parvovirus, adenovirus, and parainfluenza. Vaccines begin around 8 weeks of age and boosters are administered every few weeks until they are 16 weeks of age. Whether you obtain a puppy from a breeder, pet store, or friend, it is important to question them about the vaccination status up to that point. Infection with parvovirus can occur at any time between boosters, so it is important to have your puppy evaluated by a veterinarian and comply with the  FULL vaccine schedule.

Rabies in Washington State

By Dr. Beth Guerra

I grew up in the Midwest, where rabies was more prevalent in wildlife such as bats, raccoons, coyotes, and skunks as well as the rare household pet. In Washington state the primary animal that has been identified is the bat. Although the risk is fairly low (less than 1% of bats are infected), the virus is nearly always fatal and care should be taken to avoid exposure.

In 2011, 11 bats in Washington state tested positive for rabies in the following counties: Chelan, Clallam, Island, King, Lewis, Pierce, Snohomish, Walla Walla, and Whatcom. As of July 2012, there have already been three infected bats in similar counties. The most recent case of rabies in a household pet (cat) was in 2002 in Walla Walla county, and the last two human cases were in 1995 and 1997. All of these cases were infected with bat rabies.

Bats that carry rabies are usually clinically ill and cannot fly properly. This makes them more likely to be found by humans or household animals. There have also been reports of bats getting into houses and being found in closets or shoes. The teeth of the bat are very small and a bite may not be easily detected, especially if a person is bitten while sleeping.

Rabies is a virus that affects the central nervous system. The virus is found in saliva and transmitted via bite or scratch wounds. Household pets are exposed through wildlife and are usually the source of exposure for humans. Early symptoms may include headache and fever, but within two to eight weeks can progress to confusion, paralysis, and difficulty swallowing. If exposure is suspected, the exposed person usually begins a regimen of injections, including rabies immunoglobulin as well as the vaccine, over a two week period.  The best treatment is prevention.

As of January 1, 2012, current rabies vaccines are required for all dogs, cats, and ferrets. Rabies vaccines are readily available at veterinary clinics and are inexpensive. If a household pet is exposed to rabies, there is mandatory six month quarantine, so vaccination is best.

The following information was taken from the Washington State Department of Health:

What should I do if an animal bites me?

Clean the site of any animal bite with soap and water. Contact your health care provider and Public Health Communicable Disease and Epidemiology at (206) 296-4774 to determine the potential for rabies exposure, the need for treatment, and to decide whether or not to test the animal for rabies.

What should I do if I find a bat in my living space?

Do not touch the bat. Close the doors and windows to the room. Wait until the bat lands on the floor or a wall. Wearing leather or other thick gloves, capture the bat in a can or box without touching it. Seal the container and call Public Health Communicable Disease and Epidemiology at (206) 296-4774. The health department will help you determine if any people or pets in your home may have been exposed and can arrange to test the bat for rabies, if needed. “Bat proof” your home by making sure open windows have screens and that other small entry points—such as cracks, crevices, or holes—are sealed.

What treatment is available after exposure to rabies occurs?

Safe and effective treatment following potential rabies exposure should begin as soon as possible after the exposure occurs. Treatment is a series of shots. These shots, called post-exposure prophylaxis (PEP), include one dose of human rabies immunoglobulin (HRIG) and four doses of rabies vaccine given on a specific schedule over a 14-day period. People with weak immune systems will also need a fifth dose of vaccine and a blood test to check that the vaccine worked.

Treatment can be arranged through your health care provider and your local health department.

What can I do reduce the risk of rabies exposure for my family and me?

• Do not handle wild animals, especially bats.
• Teach your children never to touch or handle bats, even dead ones. Have your children tell an adult if they find a bat at home, at school, or with a pet.
• If you see a wild animal leave it alone.
• Do not keep wild animals as pets.
• Keep bats out of your living space by “bat proofing” your home.
• Pets may get rabies if bitten by a rabid animal. Protect them and yourself by getting them vaccinated routinely. Dogs, cats, and ferrets are now required to be vaccinated in Washington. Consult your veterinarian for vaccine recommendations.

Sources: Washington State Department of Health