By Catherine Ashe, DVM – February 20, 2.019

A few decades ago, this lethal virus was responsible for thousands of dog deaths annually. Its easy to prevent with timely vaccination, but treatment remains a challenge.

Canine distemper virus (CDV) was once a common killer of dogs and other animals. Cats, ferrets, and raccoons are also quite susceptible to contracting this virus, but dogs are considered the “reservoir” host. This means that CDV prefers to hang out in dogs, and they serve as a source of infection.

However, thanks to a very effective and readily available vaccine, distemper has become fairly rare in companion canines. Still, CDV is not eradicated, so it’s important to recognize the signs and symptoms of this virus. This is especially true if you are dealing with puppies in shelter or foster settings, “backyard-bred” dogs, or dogs that have been imported from other countries.

Currently, the most likely place that CDV is encountered is in rescued puppies in shelters. These pups often have multiple health issues and suppressed immune systems, making them more susceptible to illness. Many of these puppies have gastrointestinal (GI) parasites like roundworms and hookworms, and external parasites such as fleas, ticks, and mites. As a final insult, many have received poor nutrition prior to rescue.

All of these factors contribute to a poor immune response, so when a life-threatening virus makes the rounds, puppies are often the first infected. And when you house them in a stressful shelter, they become prime targets for opportunistic bacteria and viruses.

CDV is spread through respiratory secretions; sneezing and coughing are frequent modes of transmission. As you can imagine, in a shelter, there may be lots of both! This is exacerbated by the sort of crowded and stressful housing conditions that are often seen in rescues. Dogs can mount successful immune responses and fight the disease off, but it’s more difficult to do in a shelter.

The incubation period between exposure and the development of clinical signs in unprotected dogs may be as little as one week to as long as six weeks, with the majority of dogs showing signs within one to four weeks.

Making control of the contagion more difficult is the fact that dogs who are infected with distemper can start shedding the virus (be contagious) up to five days prior to the onset of clinical signs of the illness.

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