Oct 30, 2017
You are listening to Bark & Wag 15 Minute Vet Talk and I am your host Polly ReQua.
Canine distemper is a contagious and serious viral illness with no known cure. The disease affects dogs, and certain species of wildlife, such as raccoons, wolves, foxes, and skunks. The common house pet, the ferret, is also a carrier of this virus. Canine distemper belongs to the Morbillivirus class of viruses, and is a relative of the measles virus, which affects humans, the Rinderpest virus that affects cattle, and the Phocine virus that causes seal distemper. All are members of the Paramyxoviridae family. Young, unvaccinated puppies and non-immunized older dogs tend to be more susceptible to the disease.
The virus, which is spread through the air and by direct or indirect (i.e. utensils, bedding) contact with an infected animal, initially attacks a dog’s tonsils and lymph nodes and replicates itself there for about one week. It then attacks the respiratory, urogenital, gastrointestinal, and nervous systems.
In the initial stages of Canine Distemper, the major symptoms include high fever (≥103.5 ° F, or 39.7° C), reddened eyes, and a watery discharge from the nose and eyes. An infected dog will become lethargic and tired, and will usually become anorexic. Persistent coughing, vomiting, and diarrhea may also occur. In the later stages of the disease, the virus starts attacking the other systems of the dog’s body, particularly the nervous system. The brain and spinal cord are affected and the dog may start having fits, seizures, paralysis, and attacks of hysteria.
Canine distemper is sometimes also called “hard pad disease” because certain strains of the virus can cause an abnormal enlargement or thickening of the pads of an animal’s feet. In dogs or animals with weak immune systems, death may result two to five weeks after the initial infection.
The disease can be acquired from improperly attenuated vaccines, though this occurs rather rarely. Bacterial infections of the respiratory or gastrointestinal systems may also increase an animal’s vulnerability to the disease. Non-immunized dogs that come into any kind of contact with an infected animal carry a particularly high risk of contracting the disease.
Canine distemper is diagnosed with biochemical tests and urine analysis, which may also reveal a reduced number of lymphocytes, the white blood cells that function in the immune system in the initial stages of the disease (lymphopenia). A serology test may identify positive antibodies, but this test cannot distinguish between vaccination antibodies and an exposure to a virulent virus. Viral antigens may be detected in urine sediment or vaginal imprints. Haired skin, nasal mucous, and the footpad epithelium may be tested for antibodies as well. Radiographs can only be used to determine whether an infected animal has contracted pneumonia. Computed tomography (CT) and magnetic resonance imaging (MRI) scans can be used to examine the brain for any lesions that may have developed.
Unfortunately, there is no cure for canine distemper. Treatment for the disease, therefore, is heavily focused on alleviating the symptoms. If the animal has become anorexic or has diarrhea, intravenous supportive fluids may be given. Discharge from the eyes and nose must be cleaned away regularly. Antibiotics may be prescribed to control the symptoms caused by a secondary bacterial infection, and phenobarbitals and potassium bromide may be needed to control convulsions and seizures. There are no antiviral drugs that are effective in treating the disease.
In the more acute stages of canine distemper, it is necessary to monitor for development of pneumonia or dehydration from diarrhea. The central nervous system (CNS) must also be monitored because seizures and other neural disturbances may occur. A dog's chances for surviving canine distemper will depend on the strain of the virus and the strength of the dog’s immune system. Recovery is entirely possible, although seizures and other fatal disturbances to the CNS may occur two to three months after recovery. Fully recovered dogs do not spread or carry the virus.
The best prevention for canine distemper is routine vaccinations and immediate isolation of infected animals. Special care must be taken to protect new-born pups from exposure, since they are especially susceptible to the disease.
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