Feline Leukemia Virus Infection

Feline Leukemia Virus (FeLV) is a viral infection that can be spread between cats via exposure to infected nasal secretions or saliva that might occur under a variety of circumstances, such as mutual grooming or sharing water or food dishes. However, the virus may also be transmitted through contact with infected urine or feces, from one cat inflicting a bite wound upon another, or passed from mother to kitten during gestation or while nursing.

Once infection occurs, the virus spreads from the tonsils and pharynx to the lymph nodes of the neck, from which it journeys through the bloodstream to other organs and tissues, most notably the spleen, bone marrow and intestines. As the virus continues to replicate, it will become detectable in the blood within two weeks to one month from onset.

Is My Cat at Risk for Feline Leukemia?

Feline leukemia is by far the most serious disease that affects up to 3% of the US feline population, often with fatal results. It is most commonly found in male cats between the ages of one and six, particularly if they are permitted to spend time outdoors. Overall, up to 2% of outdoor domestic cats in the US are infected with FeLV compared to 1% of indoor cats. However, up to 13% of feral cats may be infected with the virus. Other risk factors include:

• Cats already impacted by illness are four times more likely to contract FeLV than healthy cats.
• 50% of cats plagued by chronic bacterial infections are also infected with FeLV.
• Up to 75% of cats suffering from toxoplasmosis (a disease caused by a parasite) also have the FeLV.
• Cats residing in multi-cat households are more likely to become infected with FeLV.

Types of Feline Leukemia

There are three forms of feline leukemia and any cat can become infected with more than one or even all three types. The breakdown of type and degree of infection is as follows:

• FeLV-A is common to all FeLV-positive cats and is characterized by a compromised immune system.
• FeLV-B is found in about half of all FeLV-positive cats and is responsible for leading to an increased occurrence of neoplastic disorders, such as tumors.
• FeLV-C causes chronic anemia and is present in only about 1% of FeLV-positive cats.
• Approximately 30% of FeLV-infected cats are transiently viremic, meaning that the virus only remains in the blood temporarily until it is destroyed by the immune system, often the reward of being vaccinated. However, these cats can still spread the virus by the usual means for several weeks after infection initially occurs.
• About 40% of FeLV-infected cats host the virus in the spleen or lymph nodes rather than in the blood, so they are considered latently infected and may even test negative for the virus.
• Roughly 30% of FeLV-infected cats are persistently viremic and will continue to be infected and a transmission risk to other cats for the remainder of their lives.

Symptoms of Feline Leukemia

Symptoms may vary according to the type of FeLV involved, but generally most cats will exhibit one or more of the following during the first few weeks of infection:

• Dental disease
• Skin infections
• Diarrhea
• Weakness or lethargy
• Decreased appetite
• Weight loss
• Bloody stools
• Frequent urination
• Low-grade fever
• Jaundice
• Swollen lymph nodes

Approximately 30% of FeLV-positive cats will also develop tumors as a symptom of lymphoma, or cancer. These animals may also present:

• Kidney disease
• Liver disease
• Vomiting
• Respiratory difficulties
• Cloudy eyes
• Seizures

How is Feline Leukemia Diagnosed?

There are two standard tests to check for the presence of FeLV antigens. The first is the enzyme-linked immunosorbent assay (ELISA), which detects antigens early while the virus is still in the blood and before it has spread to lymph nodes and bone marrow. The second method of diagnosis is the immunofluorescence assay (IFA), also known as the ’Hardy,’ or simply as the slide test. This test can detect the FeLV virus in white blood cells. Both the ELISA and the IFA tests can detect the virus in bone marrow.

There are further distinctions about these tests and their outcomes as noted below:

• While useful for early detection, the ELISA test is sometimes unreliable, often yielding false-positive results.
• Cats that test negative via the IFA test may still be infected but the virus escapes detection due to being only recently introduced.
• Cats who test FeLV-positive according to the IFA test are usually infected for life.

Conventional Treatment of Feline Leukemia

The good news is that approximately 70% of cats that become infected with FeLV are able to develop immunity and avoid becoming clinically ill. However, the remaining 30% of FeLV-infected cats, for which there is no cure, may have to undergo a variety of treatments to diminish symptoms, including:

• Chemotherapy (if tumors are present)
• Antibiotic therapy (to prevent secondary infections)
• Immunomodulating therapy (i.e., medication with interferon)
• Blood transfusions

Additional therapies for Feline Leukemia

In addition to adhering to a natural, holistic diet, there are several natural treatments used to combat FeLV, such as:

• Orthomolecular therapy (megavitamins)
• Glycoprotein therapy (i.e., acemannan supplementation)
• Botanical therapy to boost immunity, including herbs such as goldenseal, astragalus, red clover, cordyceps and echinacea.
• Homepathic nosodes (homeopathic versions of vaccines)