Feline Immunodeficiency Virus.

The law of natural selection means that all living species need to constantly battle their environment in order to survive hostile changes. Higher mammals, including cats, can often adapt their behaviour to help cope with these new challenges.

Bacteria and viruses are much simpler organisms but they reproduce far more rapidly, often producing several generations in a day. This makes them better able to adapt to the challenges of a changing environment by altering their genetic structure. That's why, just when we think we have a disease beaten, with a new antibiotic or vaccine, the nature of the disease changes, and we have to develop new strategies. However hard we try to be hygienic, we are surrounded by potentially harmful agents, and we rely upon our immune systems to keep us healthy. An animal that has had its immune system attacked, such as a cat with advanced Feline Immunodeficiency Virus (FIV) infection, will rapidly succumb to infections that would normally be shrugged off.

Media publicity about new super bugs does not necessarily mean that standards of hygiene are falling. We should use antibiotics sensibly, to slow down the process of bacterial antibiotic resistance, and we should maintain high standards of hygiene, particularly when dealing with patients whose immunity may be lowered by ill health. But, in the long term, we are fighting a war of science against nature, to try to prevent us returning to the era before antibiotics, when people and animals died from what would nowadays be treatable bacterial infections, and against new variations of old viruses.

New forms for old Feline Calicivirus (FCV) has been identified as one of the common causes of cat flu, typically causing some 'cold-like' signs but also tongue ulcers. Although unpleasant, cats usually recover from the infection. FCV-associated viral systemic disease is an example of a new disease that is caused by a mutation of this well-recognized virus. Fortunately, this new disease is still rare in this country, but it is worrying because infected cats are usually severely ill. In addition to the upper respiratory signs usually seen, affected cats run a high temperature, develop swelling of the head and limbs, and ulcers around the face and lower limbs. Internal organs such as the liver are also commonly affected, and up tl 50 per cent of cats that develop the infection die of it. Current vaccines do not protect against this form of the disease, and although there is no need for panic, organizers of events such as cat shows, where there are large numbers of cats, need to be particularly careful to ensure disease control measures are stringent.



MRSA in cats:
Methacillin resistant staphylococcus aureus, better known as MRSA, primarily affects humans. It can cause severe post-operative wound complications, particularly in patients whose immune system is depressed. Staphylococcus aureus is found on the skin of normal people and many carry the MRSA strain without knowing it. The normal bacteria found on the skin of
cats and dogs are different, so they are much less likely than people to be carriers. However, it has caused post-operative infections in cats and dogs, which is worrying because of its resistance to treatment with most antibiotics, and because of the risk that it could then be passed on to people.
When cats do contract the bug, it is usually from humans that are carrying it, rather than from other cats, and vet surgeries are now putting systems into place to reduce the risk of their patients becoming infected.

Advances in diagnosis one of the first steps in dealing with an infection is to identify what is causing it. Diagnostic tests have developed greatly and general vet practices can now offer almost immediate and highly accurate results of in-house tests for problems such as FeLV (Feline Leukaemia Virus) and Flv. A major new type of testing, called Polymerase Chain Reaction (PCR) , looks for sequences of DNA in a sample and can now be used for a wide range of diseases, helping to distinguish between subtle strains of viruses. It is hoped to develop a reliable test for the virus that causes Feline Infectious Peritonitis (FIP).

Vaccinations:
Vaccine manufacturers are constantly searching for new vaccines and for improvements in existing ones. In particular, the race is on for effective vaccines against FIV and FIP but we still seem to be some way off producing vaccines that are truly effective against these highly-significant cat diseases. There have been some efforts to develop vaccines that give greater protection against the range of organisms that cause upper respiratory disease. Chlamydia causes predominantly conjunctivitis, and Bordetella causes kennel cough in dogs, but has also recently been shown to be a significant infectious cause of coughing in cats. Vaccines are now available against both, and although not considered essential as part of the core cat vaccines, they are very useful in cat colonies where particular problems exist.

New drugs for the treatment of infections the struggle to develop new antibiotics that are effective against the more resistant new strains of bacteria, is constant developments in vet medicine tend to follow those in human drugs, since the cost of research and testing is enormous and the cost of the new drugs are correspondingly high. Often, it is not worth the expense of obtaining a veterinary licence for what is a very small market and vets have to use human drugs that have not been thoroughly tested in animals. Antibiotics have no effect against viruses, and anti-viral agents tend to be much more toxic.

There has been much research into the use of such drugs, particularly for humans suffering from AIDS, and some of these products have helped cats, although many products are unproven.

AZT is widely used in humans, and has been shown to be generally safe for use in cats, and to have some beneficial effect in cats infected with FIV, There is some evidence to suggest that evening primrose oil, as well as the amino acid lysine, may boost the immune system and prolong life expectancy of cats suffering from FIV and, although this is not conclusively proven, these substances are so safe that it would seem that using them has to be worth trying. One of the most interesting developments in the field of anti-viral treatments for cats has been the licensing of a product called Virbagen Omega, which contains a drug known as feline omega interferon. This is naturally produced in tiny amounts as an antiviral agent within the cat's body and has long been studied as a potential agent to tackle these types of infection. Now, advances in genetic engineering have enabled it to be produced in sufficient quantities to make it commercially viable. There is sound theoretical information about how this drug works to suggest that it should be useful in treating viral infections and there is _ anecdotal evidence of its usefulness in treating FeLV, FIV and even FIP, which has always carried an extremely poor prognosis. However, the drug is very expensive and for vets to be able to use it with confidence, we need to see more evidence of clinical trials. .

_{source Your Cat Mag.}