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(207) 846-6515 H

(207) 846-6515



FIV was first discovered in a California cattery in 1986. It is a type of virus in the category Retroviridae, subfamily Lentivirinae. Other viruses in the same subfamily include horse infectious anemia virus, sheep progressive pneumonia virus, goat arthritis/encephalitis virus and human immunodeficiency virus (HIV). Viruses are, for the most part, species specific: the virus that infects one species will not infect another. FIV is not transmissible to humans. 

Lentiviruses similar to FIV have been found in other felids, including lions, pumas, mountain lions and the Florida panther.

Cats that are infected with FIV are sometimes said to have "feline AIDS". This is incorrect, and is very unhelpful terminology. AIDS conjures images of a devastating, highly infectious disease; I do not want to downplay the potential seriousness of FIV infection, but it is not highly infectious and only very, very rarely devastating. 

FIV is present in the saliva of infected cats. In order to cause infection saliva containing FIV must get through a cat's skin or mucus membranes (gums), it will not cause infection if it is simply inhaled or swallowed. Thus, it is most effectively transmitted from infected to non-infected cats by salivary contact - bite wounds and, to a lesser extent, one cat grooming another cat.

The FIV virus is very fragile. Outside of the infected cat's body it lasts a few minutes at most. It is easily killed by common cleaning agents.

Infection is most common in male cats and free-roaming cats. It can also be transmitted from queen to kitten in utero or through the queen's milk. In experiments queens have been infected by semen, but it is uncertain and very unlikely that this mode of transmission occurs to any significant extent naturally. 

In most multiple cat households the resident cats do not commonly inflict skin-penetrating bite wounds on each other, nor do they spend a great amount of time grooming each other. Even when a cat with FIV infection is present in this type of multicat household for a very prolonged time it is still very uncommon for uninfected cats to become infected.

One veterinary text breaks FIV infection down into various phases. (This approach is helpful to our understanding of the problem, but somewhat artificial; not every infected cat progresses through all the phases in the same way or at the same pace.)

The four phases:
1. Acute: For the short time period immediately after infection a cat might act vaguely ill with lethargy and loss of appetite, or remain symptom-free.
2. Latent: Infected cats typically remain symptom-free for months to years. 
3. Early symptoms: Once cats start to show signs of their FIV infection, those signs are usually mild and persistent or reoccuring, and relatively manageable. Like the latent phase, the early-symptom phase lasts months to years.
4. Terminal phase: This final phase lasts no longer than a few months and is characterized by neurologic disorders (seizures, tremors, etc), cancer, and/or multiple serious infections. 

In phase 3 the signs of infection are due partly to a suppressed immune system (immunodeficiency syndrome) and partly  to inappropriate stimulation of the immune system (immune-mediated disease). Signs include:
- respiratory - sneezing, nasal discharge, trouble breathing
- urinary - straining to urinate, drinking and urinating too much
- skin - hair loss, excessive redness, scaliness, itch
- oral - inflammation of the gums and the mouth in general (gingivostomatitis)
- gastrointestinal - chronic diarrhea
- eye - red, painful eyes; eye discharge; rarely, blindness
- nervous system - seizures, abnormal behavior, weakness, paralysis
- tumors
- anemia (low blood volume) - weakness

We use an in-clinic blood test to screen patients for FIV infection. From the time of infection most cats will test positive within 60 days, although for a small number of cats it could be up to 4 months. If a cat tests negative we will often recommend repeating the test in 2 months for confirmation. 

If a cat tests positive with the in-house screening test we can immediately run a second blood test, sent to a referral laboratory, to confirm the positive result. 

FIV infection is not curable. Attempts to treat it have focused primarily on the same drugs used to treat HIV, such as AZT. To date (2014) this treatment has not proven to be practically worthwhile in cats.

On the other hand, treatment of the various problems that occur secondary to FIV infection is usually possible and often rewarding. Multiple large-scale studies have demonstrated that the average survival time of cats that are FIV infected is not different from that of cats that are not; this indicates that treatment of illnesses that occur secondary to FIV infection is a worthwhile undertaking. 

Owners of cats with FIV can minimize their pet's chance of becoming ill by:
confining infected cats indoors, to prevent disease transmission and to protect the infected cat from trauma and infectious diseases
feed a high quality commercial diet
avoid raw diets, and raw meat and eggs, and unpasteurized dairy products, because these are potentially sources of serious bacterial and parasitic infections
monitor closely for signs of illness including changes in social activity with people and other pets, lethargy, decreased food and/or water consumption, weight loss, halitosis
consult a veterinarian at the first possible sign of illness, and have wellness exams yearly or more often

FIV is a fragile virus that does not persist in the environment, and is transmitted primarily by bite wounds. Transmission is highly unlikely in socially stable (i.e. cats not regularly biting each other) households and properly managed shelters, boarding facilities, and veterinary hospitals. A common-sense approach to cleanliness and infection control is all that is required:
FIV is susceptible to all common detergents and disinfectants
ensure routine handwashing
ensure routine washing of all food and water bowls, litter boxes, and cages
in shelters, boarding facilities and veterinary hospitals house FIV-infected cats individually, but not in special isolation areas

Peter Smith, DVM  

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