Feline Leukemia Virus Disease is a viral infection that affects cats. With the exception of trauma, the feline leukemia virus (FeLV) is the leading cause of death in cats, killing 85 percent of cats infected for more than three years after being diagnosed with the virus. Aside from causing anemia or lymphoma, the virus can also put cats at risk for contracting life-threatening infections due to its ability to depress the immune system.
The good news is that exposure to the feline leukemia virus does not necessarily result in death; around 70% of cats who come into contact with the virus can either resist infection or clear the virus independently.
What is the Prevalence of FeLV?
FeLV infection can be found all over the world. According to estimates, approximately 1-2 percent of the cat population is chronically infected with this virus, exposed to many more. The number of cats affected varies according to the geographical location, the environment, and the cat’s lifestyle. A higher incidence of infection is observed in cat colonies where individuals are in close touch with one another.
What Kind of Disease is Brought on by this Virus?
FeLV infects and infiltrates a variety of cells in the cat’s immune system and blood-forming tissues. Invasion into a cell results in the cell’s death or a mutation (change) in the cell’s genetic code. Such a shift can cause the cell to become potentially malignant, although this change may not occur even for several years after the infection has been detected.
Because of FeLV, cancers can develop in several tissues, organs, and bodily sites throughout the body. This type of malignancy might affect various types of circulating white blood cells (leukemia) and other cells of the blood-forming tissues. The most prevalent type of tumor-associated with FeLV is lymphoma or lymphosarcoma, lymphoid cell tumors (see handout “Lymphoma in the Cat” for more information). These tumors can develop in a single or several locations throughout the body.
However, while cancer development is a possible consequence of FeLV infection, other disorders are more common. FeLV disease results in a moderate to severe immune system inhibition in a large proportion of cats. Cats with the disease may exhibit various clinical indications, and their health will progressively deteriorate over time. Thus, the diseased cat cannot protect itself against a wide range of illnesses that would not typically pose a threat to healthy cats.
FeLV-infected cats are also prone to developing life-threatening anemia, another typical occurrence (low red blood cells). Other complications of FeLV infection include abortion, severe enteritis (intestinal inflammation), neurological (nerve) disease, and ocular (eye) disease, all of which are common.
FeLV is almost always deadly. According to studies, 80-90 percent of FeLV-infected cats will die within three to four years after being diagnosed with the virus.
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Stages of FeLV
Once a cat has contracted FeLV, one of three things can happen to her:
- Abortive Infection and Immunity: A cat may contract a transitory viral illness, fight it off, and then gain future immunity due to this experience. Kittens under 16 weeks of age have a significantly lower chance of surviving FeLV infection than adult cats.
- Progressive Infection and Disease: The virus replicates, and the kitten or cat becomes infected with FeLV over time if the original FeLV infection is not overcome. Once in the bone marrow, the virus damages the immune system and finally kills the person. However, although a cat in this state may exhibit no signs of sickness for several years, FeLV-related disorders, including anemia, skin problems, and leukemia, often manifest within two to three years of being infected. Infected cats with progressive FeLV infection shed the virus in their bodily secretions (including saliva), making them a transmission source to other cats.
- Infection and regressive immunity: Cats that become persistently infected do not necessarily acquire disease due to the infection. Some cats can mount an efficient immune response against the virus while also retaining the pathogen in their bodies. Thus, a FeLV-infected cat enters a regressive or carrier condition, indicating that the cat will have a minimal probability of developing FeLV-related disorders. For the majority of cats, the regressive phase of FeLV infection appears to be just transitory. They can become virus-free within a few years of being exposed to it. The regressive infection condition of FeLV in cats makes them less likely to shed or disseminate the virus.
In contrast to cats with progressive FeLV infections, cats with regressive FeLV infections rarely shed or disseminate the virus to other cats. They cannot transmit the virus to other cats unless a veterinarian performs a blood transfusion on them.
Is Feline Leukemia a Contagious Disease?
Feline leukemia is contagious between cats. It can be passed from one feline to another by the blood, saliva, nasal secretions, tears, milk, urine, and stool of the cat infected with the disease. In most cases, cats spread this virus by biting wounds and grooming each other; nevertheless, mother cats can infect their kittens in utero and nursing. The virus can also be spread via shared resources, including food and water bowls and litter boxes; however, this is less usual. Even if they appear to be healthy, cats can still spread the illness to other cats. However, if your cat is infected with FeLV, it cannot be transmitted to humans, dogs, or other animals. The virus can only be passed from cat to cat and not from person to person. As a result, it will not affect you or any of your other pets, as long as they are not cats.
FeLV infection is most common in kittens and young adult cats, but cats of any age can become infected with the virus. Those cats exposed to the elements and contact with other cats and those who reside in a high-density setting such as a shelter or cattery are at greater risk of contracting FeLV. It is also possible for cats with a compromised immune system to become infected with the virus.
Fortunately, this virus is not exceptionally resilient and does not survive for lengthy periods in the environment. It can also be readily eliminated by using standard cleaning procedures and products.
Because of how contagious feline leukemia is, all cats should be tested for the disease before being adopted into a new household or rehomed. If you have adopted a stray cat and don’t know anything about him, keep her separated from your other kitties until he can be checked for parasites and diseases.
The Mode of Transmission of the Feline Leukemia Virus
Feline leukemia is a disease that affects cats exclusively; it cannot be spread to humans, dogs, or other animals through the environment. One cat transmits FeLV to another by the saliva, blood, and, to a lesser extent, urine and feces of the cat in question. The virus does not exist outside the cat’s body for very long — perhaps only a few hours. The most prevalent mechanisms for infection to spread appear to be through grooming and fighting. Kittens can get the disease while still in the womb or through the milk of a mother who has been afflicted. Because otherwise healthy cats frequently share the condition, even if a cat looks healthy, it may be infected with the FeLV virus and can transmit it.
On the other hand, FeLV is not a highly contagious virus, and transmission between infected and susceptible cats typically needs a protracted period of intimate contact between the two cats. Mating, mutual grooming, and the sharing of litter trays and food bowls are all examples of close contact activities. Cat bites from an infected cat have the potential to spread the virus.
Another possible cause of infection is the birth of a kitten from a pregnant cat that has been infected with FeLV. In this case, the kittens may be born infected with the FeLV virus, or they may become infected when their mother grooms them, which is more likely. In contrast, most queens infected with FeLV are infertile, and kittens born to infected queens die before they are weaned due to abortion or resorption of the fetuses.
What Happens to a Cat When it is exposed to FeLV?
It is not true that all cats exposed to FeLV will develop chronic infections. Many infected cats have a strong immune response to the virus, and approximately 30% of these cats successfully eliminate the virus from their bodies. While the illness is being treated, these cats continue to have the virus, and harm can be done during this period, resulting in disease later in the cat’s life.
Approximately 70% of cats cannot build a sufficient immune response and hence eradicate the virus from their bodies. Following infection, these cats become constantly and permanently infected with the virus, putting them at the most significant risk of acquiring FeLV-related disease in their lifetimes. These cats who have been sick for an extended time are primarily responsible for the transmission of FeLV to other cats. When a virus is first infected, it might take months or even years before any clinical disease problems manifest themselves in the body. Virus particles may be shed in the cat’s saliva constantly during this period.
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Feline Leukemia Virus Signs and Symptoms
The following symptoms may be displayed by cats who have been infected with the FeLV virus:
- Pale gums
- Poor coat condition
- Weakness and lethargy that worsen with time
- Fever
- Yellow coloration around the lips and in the whites of the eyes
- Expansion of the lymph nodes
- Infections of the bladder, skin, or upper respiratory tract
- Weight loss or loss of appetite
- Diarrhea
- Dyspnea
- Feline reproductive issues such as infertility in cats who have not been spayed
- Stomatitis — A type of oral illness characterized by gingival ulcers.
Feline Leukemia Virus Diagnosis
The diagnosis of FeLV infection is relatively simple. It is possible to perform a quick blood test that will detect portions of the virus in the blood of a cat that has been infected with the virus. This test is entirely accurate and dependable, while it is possible to receive false-positive findings on occasion. Some cats with only a temporary FeLV infection (those who can generate an efficient immune response) will test positive on the initial blood test, while others will test negative. It may be necessary to do a second test eight to twelve weeks following the initial test to distinguish between transitory and persistent illnesses. Occasionally, additional blood testing at a specialized laboratory may be required to establish the presence of infection in certain circumstances.
Your veterinarian can identify the disease by administering a simple blood test called an ELISA, which detects the presence of FeLV proteins in the patient’s bloodstream. This test is quite sensitive, and it can detect infections in cats who are still in the early stages. It’s crucial to remember that some cats will eliminate the virus within a few months and subsequently test negative for the infection.
A second blood test, the IFA, reveals the progressive phase of the infection, and cats who test positive for IFA are unlikely to be able to rid themselves of the virus completely. Your veterinarian’s office will not do the IFA test because it is performed in a laboratory. In general, cats that test positive for IFA have a dismal prognosis over the long term.
Because of the massive range of signs and symptoms associated with FeLV illness, it is more challenging to make a definitive diagnosis. It is usual to find yourself in a difficult position with FeLV infection where various diseases or disorders coexist with the virus.
Antiviral Therapy for the Feline Leukemia Virus
Eighty-five percent of cats infected with the feline leukemia virus for a long period die within three years of being diagnosed. Regular veterinary check-ups and appropriate preventative health care, on the other hand, can help keep these cats feeling better for a longer period while also protecting them from secondary infection. Physical examinations, laboratory tests, and parasite control should be performed twice a year to avoid difficulties and identify issues as soon as they occur. All FeLV-infected cats should be kept indoors and fixed as quickly as possible.
At this time, there is no ultimate cure for FeLV infection.
Secondary infections can be treated as soon as they manifest themselves, and cats suffering from cancer can be treated with chemotherapy. Cats with bone marrow failure or lymphoma that has spread throughout their bodies, on the other hand, have a poor outlook.
How to Keep Your Cat Safe from the Feline Leukemia Virus
It is almost impossible for your cat to get FeLV if you keep him or her indoors and away from other sick animals. Immunizations can be administered to cats at high risk of exposure as an additional precautionary measure, such as those who go outside or reside in shelters or catteries. It is recommended that only cats who test negative for FeLV be vaccinated. Even those cast who have received the vaccine should be tested to see whether there has been any possible exposure to the virus. The test should be performed at least 30 days after the probable exposure has occurred. A sick cat should be examined, and any cat that appears to be unwell should be tested. This is because the virus has been linked to a wide range of health problems in different people.
New cats or kittens above eight weeks are recommended to be tested for the virus before being brought to a multi-cat home. Because they may be at threat of catching the illness – even with vaccination – most veterinarians advise avoiding introducing a new cat into a household that already has a FeLV-positive feline member present. Furthermore, the stress of a newcomer may harm the FeLV-positive cat’s health.
Living and Management
It helps if you lookout for signs of disease in your cat, and you will need to communicate with your veterinarian about any necessary follow-up therapy or tests. It is highly crucial to treat small disease indicators in a cat diagnosed with the feline leukemia virus. Her body may be unable to respond adequately to mild infections and other ailments due to the virus she carries.
Cats infected with the feline leukemia virus may have an average lifespan, provided protection from other infections.
Cats with FeLV infection should be kept indoors and segregated from healthy cats to avoid viral exposure and FeLV transmission. It is critical to maintaining proper nutrition while treating any secondary bacterial, viral, or parasite illnesses.
