Treatment options for feline leukemia
Some cats with leukemia are seriously ill and die quickly, but many live for several years after being diagnosed. Death is usually caused by a secondary infection because these cats are not able to fight off bacteria and viruses.
Since there is no specific treatment for leukemia in cats, cats are given supportive care. For example, cats with anemia are given blood transfusions. Cats with infections are given tetracycline antibiotics (Doxycycline and Oxytetracycline) or Liquamycin. These antibiotics are chosen because they help eliminate a very troublesome bacteria (Haemobartonella) that worsens the anemia that accompanies the leukemia.
If your cat is dehydrated or not eating, he or she will be given fluids and nutritional supplements. Cats with gum and mouth disease are given supportive dental care. Cats can be given immune modulating drugs such as oral interferon, IV ImmunoRegulin (propionibacterium acnes), or oral acemannan. Injections into the abdomen of immunomodulator staphylococcal protein A have helped some cats with infected bone marrow. For cats that develop tumors, chemotherapy with Cyclophosphamide, Vincristine, Chlorambucil, and Prednisone may induce short periods of remission.
Veterinarians recommend giving vitamins and antioxidants to cats with leukemia, such as Soft VitaChews for Cats. It is beneficial to give Omega 3 and Omega 6 fatty acids, such as those found in Be Well for Cats and The Missing Link Ultimate Feline Formula. Enzyme toothpaste, such as C.E.T. Enzymatic Toothpaste helps remove bacteria and decrease gingivitis.

Preventing feline leukemia
If your cat is infected with leukemia, three things can happen: your cat can clear the virus, develop a latent infection, or develop an overwhelming persistent infection. Rather than relying on your cat to clear the infection, it is best to prevent it. The best prevention is to test all female cats and either prevent pregnancy or remove kittens from mothers that have tested positive for the virus before the kittens have nursed. Testing all male cats also helps prevent disease if cats that have the virus are kept indoors and away from others they might infect.
Keeping your cat healthy, unstressed, and housed in peaceful circumstances helps prevent infection. To promote health, feed as much fresh cat food with as wide a variety as possible. For example, offer cats bits of sweet potatoes, rhubarb, yogurt, liver, etc. Use calming pheromones, such as found in the Sentry Calming Collar for Cats and the calming flower remedy, Be Serene.

Should I vaccinate my cat?
If your cat already has leukemia, he or she should not be vaccinated. Vaccines are effective in cats when they have healthy immune systems, and any cat with the leukemia virus does not have a healthy immune system. If your cat is going to be vaccinated, killed vaccines rather than live vaccines are used.

Feline Leukemia Virus (FeLV) Vaccine: Vaccines help protect kittens from developing leukemia. To be effective, they should be given to kittens under four months of age. Before vaccinating, have your kitten's blood tested to confirm that no exposure to the virus has occurred. If your kitten has been exposed, giving the vaccine is not helpful.Many veterinarians do not believe the FeLV vaccine protects older cats. Either your cat has been exposed to the virus when he or she was young or not. If not, and your cat has a healthy immune system, there is little chance of your cat being infected as an adult. This is known because researchers tried to give FeLV infections to adult cats, and they could not infect the cats unless they immune suppressed them first.
Some healthy cats develop cancer called a fibrosarcoma when they are given the FeLV vaccine because their bodies react in an unhealthy manner to the material in the vaccine. The incidence of cancer is higher if cats are vaccinated for rabies at the same time and in the same area.

Getting another cat
The leukemia virus is not hardy and dies quickly in the environment. Because the virus is easily killed by cleaning with household detergents, it is not necessary to wait a long time to get another cat. Thoroughly wash your bedding, cat beds, cat toys, floors, and counters, and feel confident that your new cat can live a healthy life in your home.