Distemper used to be one of the leading causes of death in unvaccinated puppies throughout the world. Although the incidence of distemper has decreased dramatically over the years due to distemper vaccination programs, the distemper virus is still out there and can strike without warning.
The distemper virus is related to the human measles virus and can produce different disease patterns in distemper infected dogs. Dogs infected with distemper shed the distemper virus in all body excretions, with airborne transmission the most common means of distemper dissemination. Like kennel cough, distemper is highly contagious and can travel some distance on air currents.
Distemper is a multi-faceted disease; that is, it can affect a number of different body systems, including the respiratory, gastrointestinal, and nervous systems. Early signs of distemper include fever, loss of appetite, and a mild conjunctivitis (eye inflammation). These signs of distemper infection can come and go, lasting only a few days at a time. As a result, pet owners often miss or ignore this early distemper phase.
As distemper progresses, signs become more serious and extensive. Distemper can cause coughing, breathing difficulties, eye and nose discharges, vomiting and diarrhea, blindness, paralysis, and seizures. The seizures associated with distemper often have their own unique presentation, called chewing gum fits. As the name implies, dogs stricken with distemper -induced seizures will look as if they are "chewing gum". In fact, many owners, when they see this, immediately think of rabies.
The final outcome of a distemper infection depends on the extent of exposure, the strain of the distemper virus involved, and on the ability of the dog's immune system to mount a defense against the distemper virus (with the help of supportive treatment). Depending upon these factors, infection outcome can present itself in one of four ways:
The first two outcomes are self-explanatory. The third distemper outcome can result in conditions known as "hard pad" and enamel hypoplasia. Hard pad is characterized by a prominent thickening and proliferation of the pads of the feet, hence the name. Enamel hypoplasia is a term used to describe the lack of normal enamel covering the tooth surfaces. This occurs in puppies stricken with distemper at an early age, before their permanent teeth have erupted. The distemper virus attacks and kills those cells responsible for manufacturing the tooth enamel; therefore, the new teeth grow in lacking this vital component. Needless to say, teeth that lack enamel are not very strong and tend to erode quickly and becoming brownish in color.
Life-threatening side effects from distemper usually result from nervous system degeneration. Distemper dogs can show a progressive deterioration of both motor skills and mental abilities. Rhythmic muscle twitching can become so extensive that it totally disables the unfortunate pet. Seizures, paralysis, and incoordination can also become factors as the disease progress in severity.
A diagnosis of distemper is based upon a history of exposure, on the absence of proper vaccination against distemper, and on recognition of classic distemper clinical signs. In addition, direct microscopic evidence of the distemper virus within blood cells, or within scrapings of the conjunctiva of the eye or toensils, can help out the veterinarian in his/her diagnosis.
There is no specific treatment for canine distemper; as a result, supportive care with antibiotics, fluids, and anticonvulsants is indicated. Unfortunately, the overall prognosis for recovery from distemper is poor, with over 50 percent of dogs that exhibit severe signs of distemper dying in spite of good supportive care. Of those dogs that do recover from distemper, 50 percent can be expected to develop some form of nervous system complication within weeks.
Immunization is the cornerstone for preventing distemper. Distemper vaccinations should be started as early as 8 weeks of age (6 weeks if the mother has not been properly vaccinated for distemper), with booster distemper vaccines administered at 12 weeks, 16 weeks, and at 16 months of age. After that initial series, timing of subsequent distemper vaccines depends on the vaccine used, the potential for exposure to distemper, and the dog's age. Your veterinarian can advise you on the best schedule for your particular pet.
Any puppy or dog suspected of having distemper should be immediately isolated from other dogs, even if the latter have been vaccinated. Disinfection of the contaminated premises with bleach (one part bleach to 30 parts water) will also help reduce spread of the distemper virus, yet is rarely practical.