Feline Immunosuppressive Diseases

There are three viral diseases that infect your cat and have similar outcomes. We call these viruses the Feline Immunosuppressive Disease group. All three viruses can infect your cat by transmitting  the virus from one cat to another cat. All three  viruses can be fatal. All three viral diseases have little hope of cure. Testing your cat and possibly vaccinating your cat is the only hope for prevention.

Although these diseases are often grouped together, they are quite different in viral cause and clinical signs. They often hoodwink the veterinarian because there are no clinical signs early in any of these diseases. They often do not announce themselves for what they are – sneaky killers of cats.

Let’s start with

Feline Leukemia (FeLV)

FeLV or Feline Leukemia Virus is found world-wide. It is caused by  a retrovirus. The prevalence of infection varies greatly depending on their age, health, environment, and lifestyle. In the United States, approximately 2 to 3% of all cats are infected with FeLV. Rates rise significantly—13% or more—in cats that are ill, very young, or otherwise at high risk of infection.

Infected mother cat

Cats persistently infected with FeLV serve as sources of infection. Virus is shed in very high quantities in saliva and nasal secretions, but also in urine, feces, and milk from infected cats. Cat-to-cat transfer of virus may occur from a bite wound, during mutual grooming, and (though rarely) through the shared use of litter boxes and feeding dishes. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing.

Clinical Signs

During the early stages of infection, it is common for cats to exhibit no signs of disease at all. However, over time—weeks, months, or even years—the cat's health may progressively deteriorate or be characterized by recurrent illness interspersed with periods of relative health. Signs can include:

·         Loss of appetite

·        Slow but progressive weight loss, followed by severe wasting late in the disease    process

·         Poor coat condition

·         Enlarged lymph nodes

·         Persistent fever

·         Pale gums and other mucus membranes

·         Inflammation of the gums (gingivitis) and mouth (stomatitis)

·         Infections of the skin, urinary bladder, and upper respiratory tract

·         Persistent diarrhea

·         Seizures, behavior changes, and other neurological disorders

·         A variety of eye conditions

·         In unspayed female cats, abortion of kittens or other reproductive failures

Prevention

The only sure way to protect cats is to prevent their exposure to FeLV-infected cats. You can do this by:

·    Keep cats indoors, away from potentially infected cats that might bite them. If you do allow your cats outdoor access, provide supervision or place them in a secure enclosure to prevent wandering and fighting.

·    Adopt only infection-free cats into households with uninfected cats.

·    House infection-free cats separately from infected cats, and don't allow infected cats to share food and water bowls or litter boxes with uninfected cats.

·    Consider FeLV vaccination of uninfected cats. (FeLV vaccination of infected cats is not beneficial.) Discuss the advantages and disadvantages of vaccination with your veterinarian. FeLV vaccines are widely available, but since not all vaccinated cats will be protected, preventing exposure remains important even for vaccinated pets.

Feline Infectious Peritonitis

Feline infectious peritonitis (FIP) is a viral disease of cats caused by certain strains of a virus called the feline coronavirus. Cats infected with a feline coronavirus generally do not show any symptoms during the initial viral infection, and an immune response occurs with the development of antiviral antibodies. In a small percent of infected cats (5 to 10 percent), either by a mutation of the virus or by an aberration of the immune response, the infection progresses into clinical FIP. The virus is then referred to as feline infectious peritonitis virus (FIPV). With the assistance of the antibodies that are supposed to protect the cat, white blood cells are infected with virus, and these cells then transport the virus throughout the cat's body.

The Risk

Any cat that carries any coronavirus is potentially at risk for developing FIP. However, cats with weak immune systems are most likely to develop the disease, including kittens, cats already infected with feline leukemia virus (FeLV), and geriatric cats. Most cats that develop FIP are under two years of age, but cats of any age may develop the disease.

FIP is relatively uncommon in the general cat population. However, the disease rate is much higher in multiple-cat populations, such as some shelters and catteries.

Clinical Signs

Cats that have been initially exposed to the feline coronavirus usually show no obvious symptoms. Some cats may show mild upper respiratory symptoms such as sneezing, watery eyes, and nasal discharge. Other cats may experience a mild intestinal disease and show symptoms such as diarrhea. Only a small percentage of cats that are exposed to the feline coronavirus develop FIP-and this can occur weeks, months, or even years after initial exposure.

Cat with FIP

In cats that develop FIP, the symptoms can appear to be sudden since cats have an amazing ability to mask disease until they are in a crisis state. Once symptoms develop, often there is increasing severity over the course of several weeks, ending in death. Generally, these cats first develop nonspecific symptoms such as loss of appetite, weight loss, depression, rough hair coat, and fever.

There are two major forms of FIP, an effusive, or "wet" form, and a noneffusive, or "dry" form. Generally, cats will exhibit the signs of the noneffusive form FIP more slowly than the effusive form. Symptoms generally include chronic weight loss, depression, anemia, and a persistent fever that does not respond to antibiotic therapy.

Feline Immunodeficiency Virus

Virologists classify feline immunodeficiency virus (FIV) as a lentivirus (or "slow virus"). FIV is in the same retrovirus family as feline leukemia virus (FeLV), but the viruses differ in many ways including their shape.

The Infection

FIV-infected cats are found worldwide, but the prevalence of infection varies greatly. In the United States, approximately 1.5 to 3 percent of healthy cats are infected with FIV. Rates rise significantly-15 percent or more-in cats that are sick or at high risk of infection. Because biting is the most efficient means of viral transmission, free-roaming, aggressive male cats are the most frequently infected.

            Clinical Signs 

            Cat infected with FIV can have:

      ·   Poor coat condition and persistent fever with a loss of appetite are commonly seen.

·    Inflammation of the gums (gingivitis) and mouth (stomatitis) and chronic or recurrent infections of the skin, urinary bladder, and upper respiratory tract are often present.

Cat with FIV

·    Persistent diarrhea can also be a problem, as can a variety of eye conditions.

·    Slow but progressive weight loss is common, followed by severe wasting late in the disease process.

·    Various kinds of cancer and blood diseases are much more common in cats infected with FIV, too.

·    In unspayed female cats, abortion of kittens or other reproductive failures have been noted.

·    Some infected cats experience seizures, behavior changes, and other neurological disorders.

Prevention: the test and FIV vaccine

When to test:

·    If your cat has never been tested.

·    If your cat is sick, even if it tested free of infection in the past but subsequent exposure can't be ruled out.

·    When cats are newly adopted, whether or not they will be entering a household with other cats.

·    If your cat has recently been exposed to an infected cat.

·    If your cat is exposed to cats that may be infected (for example, if your cat goes outdoors unsupervised or lives with other cats that might be infected). Your veterinarian may suggest testing periodically (yearly) as long as your cat is exposed
      to potentially infected cats.

·      If you're considering vaccinating with an FIV vaccine.

      It is my opinion that cats that live in multi-cat households and cats that go outside, even occasionally, should be tested and vaccinated for the Feline Immunosuppressive Disease group. Even if the vaccines are not 100% protective, as many argue, proactive testing and vaccinating is better that no protection at all.

      Cats that live alone and never go out still have a small risk. The risk is not zero. It comes down to personal choice for you and your cat(s).

      Some information in this article was obtained through Cornell Feline Health Center, Cornell University, College of Veterinary Medicine, Ithaca, New York.

     The Providence Veterinary Hospital Blog is a publication of Peter Herman, VMD, at the Providence Veterinary Hospital, 2400 Providence Ave. in Chester, PA. Contact Dr. Herman at 610-872-4000 or visit us at http://www.providencevet.com