There are several major infectious diseases for which safe and effective vaccines are available: among them rabies, feline panleukopenia (feline enteritis, feline “distemper”), and viral respiratory infections (rhinotracheitis, calicivirus). Each of these diseases can easily cause death in an unprotected cat. We are very fortunate to be able to prevent such serious illnesses with a procedure as technically simple as vaccination.
HOW VACCINES WORK
Antigens are molecules with particular areas on their surfaces that are recognized as foreign to the body. Antibodies are protein substances produced in the body that are responsible for recognizing these antigens. They are produced by cells called lymphocytes that originate in the bone marrow and multiply in the thymus, spleen, and lymph nodes. When lymphocytes recognize that a foreign substance (antigen), such as a virus or bacterium, has entered the body, they begin copious production of antibodies specific for the invader. Lymphocytes capable of antibody production against the invader multiply to produce progeny cells capable of producing the same antibodies. Some of these progeny cells immediately begin producing antibodies, while others become resting cells that serve as the body’s “memory” of the invader. If the same (or a very similar) invader makes an appearance again later, these cells are able to respond quickly to its presence. Vaccination introduces a modified disease agent into the body. Common methods of altering an organism’s ability to produce disease are by chemical killing and by “breeding” to an innocuous state. Biotechnology can also produce vaccines that consist of harmless immunity-inducing portions of agents that cause disease when they enter the body intact. Modified viruses or bacteria are able to induce lymphocytes to produce antibodies capable of protecting the body against disease without actually producing illness. Frequently the body produces a higher (usually more protective) level of antibodies that are more specific to a disease agent on the second exposure to a vaccine, but different vaccines vary in their ability to produce a protective antibody level on first exposure. The duration of the body’s immunological memory for different viruses and bacteria also varies. These are two reasons why the number of original vaccinations necessary for protection and the frequency of booster vaccinations vary with each disease.
YOUNG ANIMALS ARE SPECIAL CASES
Additional factors influence the vaccinations of a young animal. Cats and dogs receive a small amount of antibodies across the placenta (the organ that communicates between mother and fetus before birth). They receive a much greater amount in the colostrum (first milk) and milk when they are nursing. Kittens are capable of absorbing some antibodies through their gut for several days following birth, but the first twenty-four hours are most important. The amount of antibody received against each particular disease is dependent on the level of circulating antibody in the mother. The antibody received from the mother serves primarily to protect the kitten against disease for the first few weeks of life. Whether or not a nursing kitten receives a protective level of antibody depends on how recently the mother was exposed to the disease in question or how recently she was vaccinated. The antibody a cat receives can be a disadvantage as well as being useful since it can interfere with vaccination by tying up the vaccination-introduced antigen before it can stimulate the kitten’s immune system. The protection kittens receive early in life against feline distemper is an example. Some kittens lose their protective immunity against panleukopenia (feline “distemper”) acquired in nursing as early as six weeks of age, others as late as four months after birth. Therefore, the ideal vaccination schedule is individualized for each cat, and the last vaccination is given after twelve to sixteen weeks of age. There are tests for determining the level of antibody against panleukopenia in each cat, but, in general, they are too expensive and time-consuming for routine use. The techniques of vaccination are relatively simple. Knowledge of the proper handling of vaccines and the physiology of the immune response is what makes it important to have your cat vaccinated by a veterinarian who is interested in each animal as an individual. Vaccination by a good veterinarian also ensures that your cat gets a physical examination when he or she is young, and then also later, which may reveal important changes you have missed. Regular visits during the initial kitten vaccination series also provide a time to discuss any behavior or training problems you may have with your pet and allow a young animal to become well adjusted to visits to an animal hospital. If a veterinarian vaccinates your cat without taking a thorough history or performing a thorough physical examination and discussing your pet with you, something is amiss!
RABIES AFFECTS THE NERVOUS SYSTEM
This virus an infect humans and warm-blooded animal. It causes a disease of the nervous system often manifested by changes in behavior followed by paralysis and death. The principal reservoirs of rabies in the United States are skunks, raccoons, bats, …
Any wild animal that allows you to get close enough to handle it should certainly be suspected of rabies and left alone. Cats should be supervised when outdoors to prevent exposure to rabid wildlife, especially during the night.
HOW RABIES IS SPREAD
Rabies is usually spread when a rabid animal bites another, depositing virus from its saliva into the bite wound. However, the rabies virus can enter the body through any break in the skin, through the mucous membranes of the mouth, and probably those of the nose and eyes as well. After entering the body the rabies virus attaches to nervous tissue where it multiplies. Signs of rabies usually begin between about two to ten weeks following infection, but cases have developed more than one year after contact.
TWO FORMS OF RABIES
Rabid cats usually first show changes in their temperament. At this time rabies can be particularly difficult to diagnose because the signs are so variable. A cat may become restless, apprehensive, overly affectionate, or shy. A cat will often tend to hide at this stage. Some cats may be febrile (have a fever) and may have dilated pupils. Following these early signs, the animal often becomes extremely ferocious, biting or clawing at objects without provocation. This is considered as the furious form of rabies. These animals do not feel pain. Partial paralysis of the vocal cords results in a change in voice. Convulsions may be seen and may cause death.
The second form of this virus (rabies) is a dumb form. It is mainly characterized by paralysis. A cat’s mouth may hang open and saliva may drip from it. Since rabid cats cannot ingest food or water they become quite dehydrated. More often, however, cats with the dumb
form of rabies develop difficulty walking and then paralysis of the rear legs. Eventually, total paralysis occurs.
Protect your cat from rabies so you will never have to deal with the problem of owning a rabid animal. Cats should first be vaccinated against rabies when they are three to four months of age. There are several types of vaccine available. The most commonly used types contain inactivated virus.
The vaccine is administered by intramuscular (in the muscle) injection into one of the hindlegs or subcutaneously (under the skin), usually near the shoulder blades. Protection against rabies is reached within one month after primary immunization. Vaccination against rabies is required by state law, and the same law regulates the frequency of booster vaccinations as well. The current recommendations of the Centers for Disease Control vary with the type of vaccine administered. In general, a booster shot is given one year following the original vaccination, then booster doses are given every one to three years depending on the product used. If you or your cat is exposed to a rabies suspect, that animal should be confined if possible and turned over to a public health officer for rabies quarantine or euthanasia. All bite wounds should be thoroughly washed with large quantities of soap and water and flushed with 70% ethyl alcohol, which kills the rabies virus. Whether or not your cat will be quarantined following exposure to a rabies suspect will depend on state and local regulations. However, it is recommended that exposed, currently vaccinated cats be revaccinated immediately and confined for observation for ninety days.
PSEUDORABIES MAY MIMIC RABIES
Pseudorabies, a herpesvirus-induced disease of swine that is fatal when transmitted to cat or dogs, may be confused with rabies infection. Although aggressive behavior has not been reported, the fever, lack of appetite, restlessness, drooling, and self-mutilation that often accompany this disease can look similar to signs of rabies. The animal should be eliminated if treatment is not successful. Prevent this infection by not feeding your cat raw pork.
Feline panleukopenia is an extremely common, very contagious, and often fatal viral disease that occurs in cats (both domestic and wild) and raccoons and other members of the raccoon family. The panleukopenia virus attacks rapidly growing body cells such as those in the bone marrow and the intestinal lining. As a result, the white blood count is lowered when the bone marrow is infected, the bowel becomes damaged, and the cat may die from secondary bacterial infection and/or dehydration. Although this disease is commonly called distemper, it is not at all related to canine distemper which often occurs in young dogs. Other common names for panleukopenia are feline infectious enteritis, cat or show fever, and cat plague.
SIGNS OF PANLEUKOPENIA
The incubation period (time from exposure to first signs of disease) for panleukopenia is usually about seven days, although it may vary from two to ten days. In young cats (under six months) in particular, the disease can be so severe and of such rapid onset that death occurs before an owner is truly aware that signs of illness are present. More often the first signs are fever (frequently 104 to 105°F), listlessness, lack of appetite, and vomiting usually accompanied by extreme dehydration. A cat may seem interested in drinking (some sit with their heads over or near their water bowls) but often will not drink or vomits soon after doing so. Diarrhea may accompany the first signs but often seems to develop later. The stool is
usually very watery and may contain pieces of the intestinal lining and sometimes blood.
“PANLEUK” VIRUS RESISTS DISINFECTION
The procedure for initial immunization against panleukopenia varies depending on, among other things, the immune status of your kitten and on your ability to isolate your cat from exposure to the virus before vaccination is complete. Every effort should be made to keep your kitten away from cats who might be shedding the virus and away from panleukopenia contaminated environments until vaccination is complete. The “panleuk” virus is shed in all bodily secretions and excretions and can be transmitted from cat to cat easily without bodily contact with the infected carrier cat. It is one of the most resistant viruses and can remain alive and a source of infection for susceptible cats for several months even after premises have been cleaned thoroughly. Only 0.5% formalin or hypochlorite, a 1:32 dilution of household bleach in water, can kill this virus. The best policy to follow is not to introduce a susceptible cat into premises where a cat has had panleukopenia for three to four months following the episode even if the area has been disinfected. Do not allow an unvaccinated cat to associate with strange cats. Keep him or her indoors if necessary until vaccination is complete. Keep your kitten in your lap or in a carrier and out of contact with possibly sick cats while at your veterinarian’s office.
VACCINES PROTECT AGAINST “PANLEUK”
Take your kitten to a veterinarian for his or her first vaccination at six to ten weeks of age. A good veterinarian will perform a complete physical examination before administering the vaccine. At this time he or she will also be able to answer any questions you may have about the care of your cat. Don’t be afraid to ask questions; no question is “dumb” and you may learn something very important by asking. The injection is usually given under the skin (subcutaneously) in the back between the shoulder blades and as with most vaccines, seems pretty
painless; many kittens act as if they don’t realize they are being vaccinated. Your veterinarian will ask you to bring your kitten back for a second vaccination in three weeks or more. In the meantime be sure to keep your kitten well isolated from exposure to disease. In general, two or three vaccinations are given before immunity is complete. Because there are various kinds of vaccines and variations in cats’ ages at the time of first vaccination, fewer or more vaccinations may be necessary. The important thing to remember is that no matter how young when vaccination is begun, kittens should finish their vaccines after twelve to sixteen weeks of age. If you think the series is finished or have been told that the series is finished before your kitten is this age, bring him or her back to the veterinarian for another shot.
TREATMENT FOR PANLEUKOPENIA
If your cat contracts panleukopenia, it is important to have immediate examination by a veterinarian and to get intensive treatment started early. A complete blood count is necessary to help confirm the disease (the virus causes a marked decrease in the number of white blood cells present), and hospitalization is often necessary for successful treatment. You may, however, be able to work with your veterinarian on treatment at home. Treatment consists of appropriate antibiotics, vitamins, and supportive care including fluids, hand-feeding, and antidiarrheal medication. Heroic measures such as blood transfusions have been necessary in some cases. Although panleukopenia is often fatal, there is no reason to give up at the first sign of disease. Many cats have survived severe cases to live out normal, healthy lives.