Article reprinted with permission of DVM360 – May 11,
2018. DVM360 MAGAZINE is a copyrighted publication of
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CPD ACCREDITED ARTICLE
Living With FeLV-infected Cats:
A Guide for Veterinarians and Their Clients
With proper management by the owner and healthcare
from the veterinary team, cats with this retrovirus can live
longer, more comfortable lives.
By Glenn Olah, DVM, PhD, DABVP (feline)
Feline leukemia virus (FeLV) is an RNA gamma-
retrovirus of cats found worldwide, infecting anywhere
from 3% to 14% of domestic cats depending on
geographic location, sex, lifestyle and general health 1 .
Experts speculate that the virus evolved from rats
during the late Pleistocene era up to 10 million years
ago in the North African desert. Ancestral rats and cats
roamed freely, and the virus was likely transmitted
to cats through rat ingestion or bite. 2,3 .FeLV is highly
contagious, particularly in kittens, and is readily
spread among cats in casual close contact, which
can include sharing food and water as well as mutual
grooming. However, aggression (i.e. cat-fight bites)
can also readily transmit the virus. There are three
primary outcome stages of FeLV infection: abortive,
regressive and progressive. 4 Approximately two-thirds
of cats exposed to FeLV will experience either the
abortive or regressive stage of infection, and about
one-third of cats develop progressive infection 5 . Here
are some additional details:
Abortive stage
An abortive infection occurs when a cat clears the
infection. (Cats with this stage were formerly referred
to as “regressor” cats.)
Regressive stage
While a regressive infection causes a cat to become
temporarily viraemic, the cat eventually clears the
viraemia and does not become ill from FeLV-associated
diseases. However, it does have viral DNA integrated
into its genome. 6-8 (Cats with regressive infection were
formerly referred to as “latently infected” cats.)
Progressive stage
Progressively infected cats shed virus in their saliva,
ocular and nasal secretions, urine, faeces and milk
and are thus infectious to other cats. (These cats
were formerly called “persistently viremic” cats.)
Progressively infected cats can survive months to
years, with a mean survival of 3.1 years, and may die
of FeLV-associated diseases 9 . However, with proper
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