«F.E.L.V.» or Leukémia

By the Veterinary Doctor Nathalie Vidal-Terrier

In 1964, Dr. Jarret identify the viral agent responsible for lymphosarcoma and feline leukemia virus called feline (FeLV), feline leukemia virus.

FeLV is an oncogenic virus and its discovery is particularly significant that the lymphosarcoma and tumor type as observed in cats and this virus is a model of choice in the study of virus-induced tumors.

Besides of lymphosarcoma, it appears that FeLV is responsible for many other non-tumor, as frequent as diverse and severe in cats.


A. Etiology – Epidemiology


The virus of the family Retroviridae, is very resistant in the environment. Infection occurs through direct contact then.

The contaminants are the body fluids, primarily blood but also saliva, nasal secretions, urine, feces, milk, tears.

The infectious process can proceed in several ways :

  • Vertically : the infection is transmitted by the viral genome integrated into the genome of a germ cell. The parent then sends infected directly by the genome of the virus to her offspring.
  • Transplacentally : the infected female and in a state of viremia, can contaminate its scope in utero through the placenta. This infection leads to death or premature abortion of fetuses with fetal resorption, or the birth of congenitally infected kittens at risk of developing early disease, tumor or not.
  • Horizontally : this is the most common mode of infection, an infected cat viremic infects a healthy animal. We can associate without this form of infection, the case of newborn kittens infected early in their mother’s milk. We note as well that the infection may be a more or less advanced age, cats seem susceptible to infection regardless of age.

Following infection there are three possible developments :

  • There is infection but the virus is eliminated without viremia
  • There may be a transient viremia, one can be healthy carriers of cats which can then eliminate the virus. They become resistant to reinfection.
  • There viremia persists over time and affected individuals then have a pathology linked to FeLV.

The population most affected is that of « street cats » and larger communities.


B. Clinical


B.1. Agent tumor

Agent tumor diseases of lymphosarcoma and lymphocytic leukemia of the cat, it is also lympho-proliferative diseases infrequent. We then have:

  • Malaise (anorexia, emaciation, loss of muscle)
  • Hyperthermia in advanced irregular
  • Anemia
  • Difficulty breathing
  • Eventually cardiac signs
  • Various digestive disorders (vomiting, diarrhea, intestinal obstruction)
  • Quickly chronic renal failure

 B.2. The non tumor diseases

  • Anemia
  • Atrophy of the thymus in the kitten
  • Immunosuppression leading to secondary infections chronic viral, bacterial and fungal
  • Glomerulonephritis leading to chronic renal failure
  • Abortion and fetal resorption
  • Spinal cord atrophy

Changes in kittens can be fatal within weeks.

Death occurs in the adult patient on average in the 2.5 to 4 years after being declared the disease.


C. Diagnosis and Prophylaxis


Diagnosis is made on simple blood and various laboratory techniques allow the detection of FeLV reached.

A negative result means that the animal is not carrying the virus or incubation. A positive result indicates that viremia as we have seen above may be transient or persistent. Therefore in case of doubt or symptoms not consistent with the test results, it is necessary to repeat these tests between 3 and 6 months later.

The existence of these tests can take a sanitary prophylaxis of the disease.

It is based on the distance of carrier animals (whether or not patients).

Any new person entering must be tested first.

Medical prophylaxis is also with the existence on the market of effective vaccines, while entering new individual must be not only tested but also vaccinated.

This is a fatal flaw.

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