Distemper in dogs is a viral infection that is caused by a member of the Paramyxoviridae family of RNA viruses that are similar to the viruses that cause measles, bronchiolitis, and mumps in man. The viral infection mostly targets the respiratory and gastrointestinal tracts of dogs, although there is an increasing incidence of canine distemper that invades the brain and spinal cord as well as other organs and tissues of the body such as optic nerves, urogenital structures, and epithelial tissues.
While most viral infections are self-limiting, the virulence of canine distemper virus is unmatched. When coupled with the incidence of secondary bacterial infections in dogs infected with canine distemper, this can lead to higher mortality. As a matter of fact, the mortality rate of canine distemper can be as high as 100 percent especially in unvaccinated populations.
How is Distemper in Dogs Spread?
There are three ways by which canine distemper can be spread from an infected dog to other dogs. The first mechanism involves airborne transmission. When a distemper-infected dog sneezes or coughs, it dislodges some of the viral proteins from its respiratory system into the air. These stay airborne, contaminating the air, and is readily transmitted to dogs that inhale the same air.
Since the virus can also reside in the gastrointestinal tract of infected dogs, transmission can also occur indirectly through the sharing of food and water bowls as well as other equipment that can get in contact with the saliva or even the feces of an infected dog. Other bodily fluids such as urine can also contain the canine distemper virus.
The virus can also be transmitted transplacentally. A pregnant dog that is infected with canine distemper can easily pass on the virus to its puppies through the placenta.
The virus is considered highly infectious between 6 to 22 days after getting exposed. Unfortunately, the clinical manifestations of canine distemper infection does not appear until about 14 to 18 days from initial exposure. What this typically means is that your dog may already be infected with canine distemper but you don’t know it yet, although fever may be present 3 to 6 days after exposure. Sadly, since there are no additional symptoms, it is very early to tell if the fever your pooch is showing is related to distemper exposure or not.
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What are the Signs and Symptoms of Canine Distemper?
While fever may be the earliest sign of canine distemper infection, presenting as early as 3 to 6 days after exposure, it is not a very definitive sign of distemper infection since there are myriad reasons for fever in dogs. Nevertheless, by the 14th to 18th day after infection, you should be able to see the following clinical manifestations.
- Cough that is quite difficult to differentiate from kennel cough
- Runny nose
- Excessive salivation
- Difficulty or labored breathing
- Watery eyes or thick discharge from the eyes
- Loss of appetite
With the involvement of the central nervous system, you can expect to see the following symptoms.
- Involuntary muscle twitching
- Seizures accompanied by increased salivation
- Unusual jaw movements as if chewing bubble gum
If the viral infection remains untreated, the following manifestations may be observed.
- Hypersensitivity to light, touch, and pain
- Circling behavior
- Motor incoordination
- Deterioration of motor function
- Severe seizures or convulsions leading to grand mal seizures
Grand mal seizures effectively cut the supply of oxygen to the brain leading to cerebral infarcts. In many cases this can lead to the dog’s death. In rare cases where the dog survives, blindness and paralysis almost always ensue.
Dogs that are More Vulnerable to Canine Distemper
Canine distemper mostly infects puppies that are younger than 4 months old as well as adolescent dogs that have never been vaccinated against the virus.
Treating and Preventing Canine Distemper
There is no treatment for the virus itself. The usual treatment approaches are directed at addressing the symptoms. For example, if there is fever and pain, then antipyretics and analgesics are given. If there are secondary bacterial infections, then appropriate antibiotics are administered. Diarrhea and vomiting may have to be managed using antiemetics, antidiarrheals, and aggressive intravenous therapy.
Prevention offers a much better hope of protection against canine distemper. All puppies below 4 months old should be vaccinated between the ages of 6 and 8 weeks with repeat vaccination every 2 to 4 weeks until the puppy reaches 4 months of age.
Canine distemper is a serious infection in dogs. While its treatment is primarily supportive, there is a much better chance of ensuring ample protection in dogs with appropriate and timely vaccination against the virus.
- Anna Burke, Distemper in Dogs – Causes, Symptoms, & Treatment, The American Kennel Club
- Canine distemper, American Veterinary Medical Association