By Dr. Jennifer Coates
Canine distemper used to be very common in North America but is now mostly involved in smaller, local outbreaks or diagnosed in shelter situations. However, any dog who is not fully vaccinated is still at risk for developing this potentially fatal disease.
Canine distemper is highly contagious. Dogs with distemper shed the virus in their urine, saliva, and respiratory secretions. Virus particles from the environment can then enter the body of a susceptible dog through the mouth or nose and travel through the lymphatic and circulatory systems to invade the respiratory tract, eyes, gastrointestinal tract, skin, and nervous system.
When a dog is coming down with distemper, the first signs that an owner typically notices include drainage from the nose and eyes, coughing, and difficulty breathing. Most dogs will also have a fever, be somewhat lethargic, and will not be eating well, if they are eating at all.
As canine distemper progresses, the virus does more damage to the lining of the gastrointestinal tract. Infected dogs will start to vomit, have diarrhea, and become increasingly dehydrated. The diarrhea may contain blood. The race is on between the damage the virus is causing and the immune system’s ability to mount an effective counterattack.
Around the same time that vomiting and diarrhea develop, changes to the dog’s skin may also become evident. The skin covering the nose and footpads can be come hard, thick, and can crack. Puppies sometimes develop pustules (pimples on the skin that contain pus) and skin inflammation. At this point, recovery is still possible if the dog receives appropriate veterinary treatment.
In some dogs, the canine distemper virus also invades the central nervous system. Signs that this has occurred include twitching, difficulties with balance, stiffness, extreme weakness, jaw snapping or clicking, and seizures. Neurologic symptoms can occur at the same time as the other clinical signs of distemper or several weeks later, when the dog appears to be on the road to recovery. No matter when neurologic signs develop, the chances that a dog will survive the infection drop dramatically.
Rarely, fully vaccinated elderly dogs can develop neurologic symptoms like difficulty walking, head pressing, and pacing that appears to be caused by inflammation associated with the presence of canine distemper virus in their brains. These individuals may or may not have had an episode of distemper when they were younger. The reason for why some dogs develop “old dog distemper” but most do not is unclear.
Most cases of distemper can be prevented with a series of vaccines that start when a puppy is around 7-8 weeks old. Puppies receive three or four distemper vaccines roughly every three weeks until they are 3-4 months old. Dogs should be revaccinated one year later. Then, most dogs only need a distemper booster every three years, or they can have an annual vaccine titer to check their immunity level.
Distemper is potentially fatal. Protect your dogs by keeping their vaccinations up to date.