By Dr. Jennifer Johnson

While we place top priority on a good physical exam at your pet's annual visit, vaccinations still play a very important role in preventative health care.

The first vaccine is actually for a combination of several diseases that can put your dog at risk. They include canine distemper, hepatitis, parainfluenza and parvovirus. There can be some variation depending on the manufacturer, but most contain these four.

Canine distemper is readily available in the respiratory secretions of an infected pet and is commonly spread by coughing. Clinical signs vary depending on the virulence, or strength, of the strain, and range from milder signs consistent with an upper respiratory infection, to generalized illness. This disease also can have significant effects on Fido's neurological system, causing tics, tremors and even seizures. This disease is frequently fatal, and treatment is supportive only. Supportive treatment means that there is no specific method to kill or combat the causative organism and the medical team can only support the pet's immune system while it is fighting a disease. Appropriate vaccination is a terrific prevention for this disease, but vaccines must be periodically updated to maintain their protection.

Infectious hepatitis, on the other hand, is very stable in the environment and very hard to kill with disinfectants. It can lay in wait long periods of time for your unvaccinated pet to come across its path and then strike suddenly. Owners often believe their pets have been poisoned because the animal can become sick and die within as little as four hours once the virus has taken hold. This virus affects multiple organs, and treatment is only symptomatic and supportive. Appropriate puppyhood vaccination can provide lifelong immunity to this disease.

Parainfluenza primarily causes an acute, self-limiting cough, but in rare cases can cause encephalitis and an accumulation of fluid around the brain known as hydrocephalus. There is no treatment for the neurological form of this disease, but routine vaccination for the respiratory strain is thought to offer some cross-protection.

Parvovirus is an intestinal virus that causes vomiting, which can be severe, followed by diarrhea and rapid onset of dehydration. Death can occur in as little as two days once the illness has begun. Treatment is supportive, and while typically rewarding, it usually requires a stay in the hospital that can be very costly. Vaccination is most important in growing puppies, as they are the most likely target of the virus, and become the most ill with infection Periodic boosters also are required to maintain effective immunity.

The next vaccine is commonly known as the "kennel cough" vaccine. It is actually a vaccine against the gram-negative bacteria called Bordatella bronchiseptica. While vaccinated animals still are at risk for this disease, it requires a larger exposure, and infection typically results in only a pesky cough that is self-limiting and resolves without treatment. In the unvaccinated animal however, pneumonia is a real concern and can quickly become life-threatening. This vaccine is similar to human's flu vaccine in that it requires regular updating to remain effective.

The last vaccine is, of course, the rabies vaccine. This vaccine is required by law, and can only be given by your veterinarian. Rabies is a fatal disease with significant public health concerns. Vaccination is recommended after 3 months of age, and then must be boosted at their first annual visit. After that, it depends on the type of vaccine your veterinarian is using and the laws of the city or county where you live. Your veterinarian's recommendations should be strictly followed to help guarantee appropriate immunity.

In addition to these vaccines, there are several, pet-specific vaccines that some pets will need, and others will not. Any questions you have about your pet's vaccines should be discussed with your veterinarian.

Coming March 7: Vaccines for cats.