Page 348 - Problem-Based Feline Medicine

340 PART 6 CAT WITH WEIGHT LOSS OR CHRONIC ILLNESS

● Bite wounds are considered a primary source of adenopathy, AIDS-related complex (ARC), and AIDS.
infection. However it may be difficult to distinguish these stages
● Vertical transmission either transplacentally or via clinically.
infected milk occurs experimentally but is of ques- ● The acute phase begins about 4 weeks following
tionable significance in natural settings. infection and may persist for up to 4 months.
● Horizontal transmission in multiple cat households – Mild lymphadenopathy, neutropenia, fever,
via food bowls, mutual grooming appears rare. malaise and diarrhea may occur.
● Sexual transmission is not thought to be a signifi- – These signs may be mild and go completely
cant route of infection. unnoticed by the owner.
– These cats will usually test seronegative for the
The prevalence of FIV infection varies with the popu-
virus.
lation studied:
● The asymptomatic carrier phase may last for
● FIV infection in healthy cats in the United States
months to years.
and United Kingdom ranges from 2–3%, compared
– Despite being asymptomatic, significant immune
to rates approaching 30% in sick cats or cats with a
aberrations may be present
high risk of exposure.
● Persistent generalized lymphadenopathy lasts for
● Male cats are three times more likely to be
less than 2–4 months.
infected than female, especially male entire cats.
– Poor hair coat, fever and leukopenia may be
● Risk of infection is greater in free-roaming and
noted.
feral cats than indoor cats.
● The terminal clinical phase can sometimes be
FIV has a worldwide distribution in domestic cats. divided in to ARC and AIDS.
● ARC is the presence of clinical disease that does
The course of the disease following FIV infection is
not fulfill the criteria for AIDS.
dependent on a number of host- and virus-related fac-
● AIDS is the final stage of the infection.
tors, such as the age and health status of the cat and the
– Profound weight loss (> 20% of body weight)
strain and dose of the virus.
and a variety of opportunistic infections.
Acute infection involves rapid replication of virus in – Frequently there is persistent leukopenia and
lymphoid organs and salivary glands. anemia.
– Additionally, cats may have neurological dis-
Although CD4+ (helper) and CD8+ (cytotoxic) T lym-
ease or malignancy.
phocytes may be infected by FIV, FIV selectively
– Average life expectancy is less than 1 year.
destroys CD4+ cells.
● The ratio of CD4+ to CD8+ becomes “inverted” in Many diseases found in the asymptomatic phase
cats with FIV because of the relative lack of CD4+ may or may not be related to the virus.
cells.
Immunosuppression leads to opportunistic infections
● The lack of CD4+ leads to the immunosuppression
with bacterial, fungal or protozoal agents.
associated with many of the clinical signs of FIV
● Little good statistical evidence is available to show
infection.
that there is a higher incidence of many of these dis-
Many cats remain completely asymptomatic for years, eases in FIV-infected cats.
despite severe lack of CD4+ lymphocytes. ● Some studies indicate that these diseases may be
more severe in the FIV-infected cat.
Clinical signs Certain disease processes have been directly associated
with the terminal clinical phase of the disease.
Clinical signs are very variable from cat to cat, and may
● Chronic ulceroproliferative stomatitis is com-
be a direct effect of the virus or secondary to immuno-
mon, and may be associated with concurrent cali-
suppression.
civirus infection.
The infection can be divided into stages: acute, ● Ocular disease including uveitis, glaucoma, infil-
asymptomatic carrier, persistent generalized lymph- tration of inflammatory cells in the posterior chamber