Feline Leukemia Virus - Prevention

Prevention

Vaccines for FeLV are available (ATCvet code QI06AA01 and various combination vaccines), though no currently available vaccine offers 100% protection from the virus. Serious side effects have also been reported as a result of FeLV vaccination; in particular, a small percentage of cats who received FeLV vaccines subsequently developed vaccine-associated sarcomas, an aggressive tumour, at the injection site. The development of sarcomas with the use of the old FeLV and other vaccines may be due to the inflammation caused by aluminium adjuvants in the vaccines. It is worth noting that no causal link has been demonstrated between sarcomas and vaccination, that no statistical difference has been shown between prevalence of Sarcomas in those animals vaccinated with adjuvented or unadjuvented vaccines, and that the occurrence of sarcomas is significantly lower in Europe and Great Britain than the USA regardless of the use of similar vaccines.

Merial produces a recombinant vaccine consisting of canarypox virus carrying FeLV gag and env genes (sold as PUREVAX FeLV in the USA and Eurifel FeLV in Europe). This is thought to be safer than the old vaccine as it does not require an adjuvant to be effective. Although this is a live virus, it originates from a bird host and so does not replicate in mammals. However, it has not been shown to reduce the incidence of sarcomas in any clinical or field study.

Since the virus is very weak and dies within two hours in a dry environment, the incidence of transmission will drop considerably if the litterbox is kept from remaining damp between uses. One method is to clean all damp litter out of a standard box after each use; however, this is sometimes not practical.

Another option is a specialized three-part litterbox that uses either a ground corncob or safflower seed litter in a slotted top unit, which allows the liquid to drain into a reservoir that is emptied regularly. The litter material air-dries quickly, thus killing the virus quickly.

This litterbox was originally designed for diabetic cats, to allow regular testing of the sugar level in the cat's system. By coincidence, the box also helps prevent FeLV infection between household cats.