Neurological Diseases Linked to Vaccines for Dogs

Vaccines for dogs are designed to give the animals boosted immunity to specific diseases, protecting them if exposed to it in the future. Vaccines fall into two categories, "dead" vaccines and "modified-live" ones. Modified-live vaccines contain live but altered strains of the disease. Dead vaccines contain strains whose disease-causing capabilities were killed via heat or chemical exposure. Live vaccines can trigger symptoms of the disease the vaccines were designed to prevent as well as other associated neurological diseases.

Coonhound paralysis is a neurological disease known in veterinary terms as idiopathic acute polyradiculoneuritis. Its name is derived from rural legend that coonhounds bitten by racoons develop the disease. But any breed can be affected. The modified-live rabies vaccine can trigger coonhound paralysis. It attacks the dog's autoimmune system -- specifically the nerves directing muscle activity. Its leading symptom is a type of paralysis often referred to as floppy dog syndrome. It begins with weakness in the hind end and quickly spreads to the rest of the dog's body. Blood and urine testing is the first step toward diagnosis, but they can be inconclusive. Use of a more expensive serum reaction to raccoon saliva is the best indicator. Dogs do recover from this disease but, in most cases, only after a long and expensive treatment regime.

The use of vaccines in the fight against Lyme disease among canines is one of the most heated debates in veterinary medicine today. Several vaccines are approved for use in dogs. The purpose is to protect dogs from the saliva of Lyme-infested deer ticks when the insects bite dogs. The use of the vaccines is most widely recommended in New England and western Great Lakes states where deer ticks are most prevalent. However, areas west of the Cascade Mountain range in the western United States also have relatively high populations of deer ticks. Manufacturers of the vaccines recommend each dog be individually evaluated for the use of the vaccine. Dogs who spend most of their lives indoors may not be candidates for the vaccine. In some cases, dogs receiving the vaccine developed the classic symptoms of Lyme disease: high fever, loss of appetite, swollen lymph nodes, joint inflammation and neurological disorders. Although vaccines exist, they are controversial because they may not prevent reinfection and because many complications from reactions have been reported, including seizures, cognitive impairment and neuropathy, or nervous system damage.

Most dogs are vaccinated against canine distemper, which is an extremely contagious viral disease causing inflammation of the brain. Veterinarians call it postvaccinal canine distemper virus encephalitis. Some dogs do react to the modified-live distemper vaccine by developing the symptoms of the disease itself. These symptoms include seizures, loss of coordination, behavioral changes and cognitive impairment. Pneumonia is another condition that can develop due to distemper. Once a canine is infected, either by contracting from another dog or reacting to a vaccine, the virus remains in the dog's system for up to one month. Treatment includes isolation from non-diseased dogs and supportive treatment via intravenous fluids to ward off dehydration. Veterinarian-prescribed antibiotics tackle secondary bacterial infections. Sedatives control seizures. Dogs do recover, but treatment is often a lengthy battle.

Vaccine-induced rabies, or rabies-vaccine-induced encephalitis, has symptoms that appear 10 to 21 days post injection if a modified-live vaccine is used and the canine reacts to it. These symptoms mirror those of rabies: limpness, paralysis and brain and spinal cord inflammation. Unfortunately, vaccine-induced rabies, just as with rabies not related to vaccines, is incurable. The canine infected via a vaccine-induced rabies is not infectious to others but will not recover from the disease.