Understanding Feline Viruses: FeLV, FIV, and FIP

FeLV, FIV, and FIP: What do these three have in common?

Actually, they have quite a bit in common because they are all viral diseases of cats and don’t have a cure. Also, no cat guardian wants to be told that their cat has been diagnosed with any one of these conditions. However FeLV and FIV arguably have a worse reputation than they deserve, whilst FIP remains definitely the ‘bad boy’ of the bunch.

Feline Viruses 101

OK, so what do those abbreviations stand for?

• FeLV: Feline leukaemia virus
• FIV: Feline immunodeficiency virus
• FIP: Feline infectious peritonitis

Mention any one of these three and it’s enough to make a cat guardian shudder. However, these feline viruses are as different as apples, pears, and oranges; each is passed on in a slightly different manner to cause a variety of clinical signs.

Who’s At Risk?

Let’s put some clear water between each of these feline viruses by looking at how they are transmitted, and therefore which cats are at greatest risk.

FeLV

• This virus is spread in saliva and requires close contact with an infected cat for it to spread.
• Most commonly FeLV is spread by cats grooming each other or sharing a water bowl.
• Kittens in the womb can be infected via the placenta or their mother’s milk.
• Cats are most commonly infected when young and become ill later in life due to the long incubation period.

FIV

• This requires the virus to enter the blood stream.
• Most commonly disease is spread via fighting and bite wounds.
• Unneutered male cats are at greatest risk as they are most likely to fight.
• A litter of kittens born to an FIV positive mother stand a 25% chance of being infected.

FIP

• FIP is caused by a mutation of the relatively innocuous Corona virus, the latter being a common cause of stomach upsets and diarrhoea in cats.
• The virus mutates each time is passes through a cat; therefore repeated contact with faeces greatly increases risk.
• Multi-cat households are most at risk because of sharing litter trays. This includes homes with 5 or more cats, breeding establishments, catteries, and shelters.
• Those with a weak immune system such as kittens or the elderly are most prone to infection.

What Signs Do I Look For?

Ok, FeLV and FIV share an affinity for attacking the immune system, whilst FIP causes leaky blood vessels. So what does this mean in terms of symptoms?

FeLV

• Average survival time after diagnosis is 3 years
• The virus may target the white blood cells that fight infection and make the cat more vulnerable to bugs
• FeLV can cause anaemia leading to lack of energy and weakness
• FeLV sometimes floods the gut with cells that cause diarrhoea and weight loss

FIV

• After infection the cat may remain healthy for years
• The immune system is weakened so the cat is more vulnerable to serious infection, for example a simple cold turning to pneumonia
• Some cats typically develop long term inflammation of the gums
• The signs can be non-specific such as weight loss, poor appetite, or tummy upsets

FIP

• Once diagnosed, the average survival time is around 5 weeks (wet FIP)
• The cat may have breathing difficulties
• The cat’s belly becomes swollen
• Fever
• Diarrhoea and tummy upsets
• Poor appetite

The Difficulties of Diagnosis

Diagnosing these conditions is anything but straight forward.

FeLV and FIV

A variety of tests are available which work in different ways. The tests most commonly used in vet clinics detect the immune system’s response (i.e. the presence of antibodies) to the virus, but this doesn’t predict whether the cat will become sick or fight off infection. The test acknowledges the body has mounted a defence, but doesn’t predict if it is successful or not.

Your vet may suggest a repeat test in 3 – 4 weeks (to see if the antibodies have subsided, in which case the cat is now clear) or run a different test to look for the ‘smoking gun’ and the presence of virus itself.

FIP

How do you distinguish between the harmless version of Corona virus and the deadly mutated form? The answer is a trick question because science has yet to find a way to do this. Instead your vet uses evidence from the changes in antibody level to Corona virus, clinical signs, fluid analysis, and the presence of certain proteins to assemble a strong case for or against FIP infection.

The most reliable method of diagnosis is a biopsy of tissue from the liver or kidney of the sick cat.

What are the Treatment Options?

What does unite these feline viruses is that there is no cure.

Unlike bacterial infections which respond to antibiotics, the latter do nothing to kill viruses. However, antibiotics do have an important role to play because they are used to fight secondary bacterial infections which the immune system was too sick to combat.

Thus for any cat diagnosed with one of these feline viruses, if they become off colour it’s critical to take them promptly to the vet. Whilst the vet cannot kill the underlying cause, they can support the cat’s immune system so they don’t take a turn for the worse.

In recent years some vets have started using feline Interferon in these cases. Whilst Interferon is not a cure, in some cases it definitely seems to help and may extend life.

What about Prevention?

FeLV is alone in having an effective vaccination that is in wide usage. This can be given from 9 weeks of age and requires regular booster injections to keep full protection.

Since FIV is largely spread through fighting, neutering your male cat is of huge benefit since it decreases his likelihood of wandering off and getting into scraps.

Likewise, you can decrease the chances of FIP by cleaning litter trays every day, keeping less than five cats, and ensure each cat has their own litter tray.