Page 942 - Clinical Small Animal Internal Medicine

880 Section 9 Infectious Disease

– If prior exposure to FeLV needs to be known: uncommon, even in the absence of medical treatment.
VetBooks.ir analysis of the FeLV situation in a cat colony with Some FeLV‐positive cats can live without major disease
FeLV problems.
complications for years with routine prophylactic care,
– If the cat is used as blood or organ donor: FeLV can
be transmitted by transfusion of FeLV provirus‐pos- good husbandry, minimal stress, and avoidance of sec-
ondary infections. Infected cats should be kept strictly
itive blood. Antigen testing is not sufficient. indoors to reduce the risk of exposure to infectious
Test sick cats for the presence of FeLV provirus in the agents and prevent transmission of the virus to other
●
blood (PCR). Confirmatory of positive or questionable cats. Physical examinations focusing on external para-
antigen tests; true antigen‐positive samples are highly sites, skin infections, dental disease, lymph node size,
provirus positive. and body weight should be performed semiannually,
– Early infection: provirus PCR from blood tests along with a routine program for parasite control and
earlier positive than antigen tests. annual fecal, complete blood count, chemistry panel, and
– If prior exposure to FeLV needs to be known: urinalysis testing. All infected cats should be neutered.
analysis of obscure clinical cases, analysis of the Owners should be advised to watch for signs of FeLV‐
FeLV situation in a cat colony with FeLV prob- related disease, particularly secondary infections.
lems, etc. Although FeLV‐positive cats often respond well to
Test any cat for the presence of FeLV viral RNA in the treatment for secondary infections, therapy for such
●
blood (RT‐PCR). Early infection: RT‐PCR tests earlier infections or other illnesses should be early and aggres-
positive than provirus PCR and antigen tests. Not fre- sive because of immunocompromise. Because FeLV is
quently used. historically associated with rapid and grave disease, the
modern prognosis varies considerably depending on
Kittens can be tested any time for antigenemia – mater- husbandry, veterinary care, and individual immune sys-
nal antibodies do not interfere with the p27 testing. A tem variation.
confirmed positive result is conclusive, while a negative
result is not always; in some cases the kittens became
positive only after weeks to months. Each kitten should Prognosis
be tested individually.
Large‐scale studies have demonstrated an average sur-
vival of 2.4 years after diagnosis among positive cats
Treatment (versus six years after testing for negative control cats),
with 50% mortality in two years and 80% mortality by
Unfortunately, no curative treatment currently exists to three years after diagnosis. Progression of disease is
cure retroviral infection. In vitro studies have yielded much more rapid in kittens, whereas some adult cats
promising results suggesting virus‐suppressing activity remain healthy for many years and may succumb to con-
of human FDA‐approved drugs used to treat HIV and ditions unrelated to their retroviral status.
other myelodysplastic syndromes against FeLV virus
(e.g., raltegravir, tenofovir, gemcitabine, decitabine).
Further research is needed to demonstrate efficacy and Prevention and Control
safety in vivo and in field trials, as well as to address
affordability of these drugs for most cat owners. Feline Feline leukemia virus is unstable in the environment and
interferon‐omega and human interferon‐alpha have is susceptible to all common detergents and disinfect-
been associated with improved survival, but concerns ants. In a hospital or boarding setting, infected cats may
surrounding availability, cost, and absence of strong be kept in the general population as long as they are
evidence in controlled field studies have limited their housed in separate cages. Medical and surgical equip-
widespread integration into standard treatment proto- ment contaminated with body fluids, even when dried,
cols for FeLV. can be fomites for infection. Thorough cleaning and
Anecdotal reports of various antiviral and immuno- sterilization of equipment, strict attention to washing
therapeutic agents to reverse viremia, improve clinical contaminated hands, and avoiding reuse and sharing of
signs, and prolong survival are abundant. Controlled single‐use and consumable supplies between patients are
studies using naturally infected cats have either not been critical practices to prevent iatrogenic transmission.
performed or have not confirmed anecdotal observa- Feline leukemia virus vaccines are noncore and are
tions. Treatment efficacy must be demonstrated in intended to protect cats against FeLV infection or reduce
controlled clinical trials, because spontaneous reversion the likelihood of persistent viremia. Types of vaccines
to seronegative status or prolonged survival is not include killed whole virus, subunit, and genetically