by Roy F. Dvorak
Canine distemper virus or CDV is one of many canine viral diseases. Distemper not only affects dogs and cats but also harbor seals, ferrets, the African lion and other mammals.
Puppies lose their maternal antibodies by the time they are three months old. Therefore, CDV may be found in puppies 3 to 8 months old that have not been vaccinated, especially in kennel or shelter litters. Most canine veterinary manuals recommend that a brood bitch receive a booster vaccination before she is bred.
CDV is usually transmitted through the air. However, it can be transmitted through physical contact with saliva, urine, feces, and probably human hands. The virus itself has a high mortality rate in the environment. This implies that for a dog to get the virus, it probably came in contact with an animal that is already infected or probably from a human hand that carried the virus. For example, a litter of puppies are always making contact with each other and being picked up by people. The means of transmittal in this instance is probably due to poor hygienic conditions in the whelping area or poor hygiene practices on the part of a breeder.
The disease typically goes through two stages. By the 3rd day after exposure, a fever develops. There will be a watery discharge from the eyes and nose. The puppy may become lethargic and not eat. After a few days, the discharge turns to a thick yellow discharge (one article indicated a green discharge). Diarrhea is a problem at this point and can cause dehydration in a few days. The symptoms of the first stage of CDV may occur anywhere from 3 days to 2 weeks after the initial exposure. If the maternal antibodies are sufficiently strong, the puppy will recover sometime during this period. According to the UC Davis School of Veterinary Medicine Book of Dogs, the "most significant death loses in kennels occur in pups 5 to 7 weeks of age". However, puppies that developed a fairly strong immune defense, may terminate the spread of the virus and expel it from their bodies. This usually occurs around 8 or 9 days after the initial exposure. These puppies will grow up to be very normal healthy dogs.
In the second stage of CDV that begins at 2 to 3 weeks after the initial exposure, some dogs may develop signs of brain involvement. Depending on the level of the immune response of the puppy, the CDV may take one of 3 courses and will effect:
The respiratory signs (inflammation of the nasal passages and mucus membranes of the eyes) and the intestinal signs (diarrhea and dehydration) are followed by the neurological signs (circling, head tilt, rapid eye movements, partial paralysis, paralysis, convulsions, and insanity). Convulsions here mean seizures. According to the Dog Owners Home Veterinary Handbook "Dogs with brain involvement usually do not survive".
There is no cure for distemper. Antibiotics will not stop the spread of the distemper virus. They can only help to avoid the secondary complications, such as pneumonia, that may result. Fluids should be administered to counter act the effects of diarrhea.
Only through the use of CDV vaccinations can the disease be prevented. Annual distemper booster vaccinations are recommended and most states require that distemper vaccinations be current in all dogs. Recommended periods for puppy vaccinations are at 6 to 8 weeks, 10 to 12 weeks, and 14 to 16 weeks and then on an annual basis.
In addition to the MRI on Korie, we also had a spinal tap - CSF analysis performed. Korie was under general anesthesia for the MRI and the cerebrospinal fluid was collected at this time. The results from the CSF were normal. In the words of Dr. deLahunta "Cerebrospinal fluid (CSF) is a clear, colorless fluid that surrounds and permeates the entire central nervous system (CNS) and therefore protects, supports, and nourishes it." The CSF analysis is the best test to determine if any central nervous system inflammatory disease (i.e., distemper) is present. The white blood count (WBC) and the protein levels in Kories spinal fluid were both within normal limits. There is an accepted standard or count for the WBC and protein levels of the fluid. Any increase in the levels of these values is cause for concern. The presence of any inflammatory disease would be indicated by an increased protein level in the fluid. Similarly, the presence of any bacterial or fungal disease would be shown by an increased white blood count. The table below, derived from Dr. deLahuntas book Veterinary Neuroanatomy and Clinical Neurology shows the relationship between normal CSF readings and those associated with a disease.
According to Oliver and Lorenz in their text Handbook of Veterinary Neurology, "Increased WBC and increased protein levels are expected with active inflammatory diseases. . . . Any disease that causes degeneration of nervous tissue without inflammation will cause an increase in CSF protein with little or no increase in cells". As one can observe from the above table, nothing in Korie's CSF analysis indicates that any problem exists. From the CSF analysis, Korie has no disease that causes inflammation of the spinal tract.
In the 40s and 50s John Paul Scott and John L. Fuller assembled a team of people to study the social behavior of dogs. Their research lasted nearly 13 years and involved the study of hundreds of dogs that were raised from birth to 1 year of age. Several factors such as feeding, sanitation, and disease control needed to be considered regarding the environment where the puppies were raised. All of their test puppies were given distemper vaccinations. The vaccinations were tested, unintentionally, when a dog with latent distemper was introduced into their test environment. All puppies that were not completely vaccinated acquired distemper. Their project was halted for 6 months to bring the distemper virus under control. As a result of the distemper epidemic, the vaccination schedule was changed to begin the vaccinations at 8 weeks of age, the time when puppies begin to lose their acquired immunity.
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