Feline Leukemia Virus (FeLV) ✪ FeLV is distributed worldwide. The domestic cat is the predominant host, but the virus can also infect other felidae Navies 2011

Etiology  FeLV retrovirus in family Oncoviae  Subgroups A.Subgroup A: All infected cats have this type, causes immune suppression B.Subgroup B: 50% along with subgroup A Neoplastic Disease (abnormal tisue growth) C.Subgroup C: Isolated from 1% along with subgroup A Can sometimes have all three

History The Name "Feline Leukemia Virus" is a misnomer stuck. FeLV is NOT leukemia, but leukemia was one of the first diseases associated with the virus, and thus, the name was applied. By the time it was discovered that this actually was a virus and not leukemia, the term had already stuck and was in popular use. Discovered in1964 in a cluster of cats with lymph sarcoma

History The feline leukemia virus (FeLV) was discovered in 1964 in a cluster of cats with lymphosarcoma. The observed clustering of cases of feline lymphosarcoma suggested that FeLV was an infectious agent for cats. The development of a simple immunofluorescent test for FeLV permitted a seroepidemiological study to be undertaken on the distribution of the virus in cats living in their natural environment. Over 2000 cats were tested, and the results showed conclusively that FeLV is an infectious agent for cats.

Signalment  Young kittens  Males are 1.7x more likely to be infected  1-6 years of Age  All breeds  Studies indicate that it cannot be passed on to other species. Cats only.

Transmission  Incidence is directly related to the population  Healthy cats can transmit this virus, they can be a carrier  Large quantities are secreted through saliva  Tears, urine, & feces (less likely but still possible)  Vertically & Horizontally  Enveloped  Virus is unstable within the environment close contact must occur for infection to take place  Incubation Period: about 8 weeks  Some strains of FeLV can be grown in human tissue cultures. This has led to concerns of possible transmission to humans. Several studies have addressed this concern; none have shown any evidence that any zoonotic risk exists

CLINICAL SIGNS  Regressive form: transient infection  Progressive infection (primary viremia): persistent viremia and no clinical signs. Diagnosed by ELISA  Active form: Clinical signs and secondary viremia. Point of no most cats will be infected for the rest of their lives. Diagnosed by IFA/ ELISA

Clinical Signs  Fever  Anorexia  Weight loss  Anemia  “Secondary infections”: non healing wounds  Vomiting & diarrhea  Spontaneous abortion  Renal disease  Tumors of lymphoid origin LYMPHOMA  Neurological signs ★ Anisocoria is occasional within FeLV patients Pansystemic disease

Clinical Signs Vary because so many body systems can be affected Loss of appetite, fever, weight loss, and weakness are the most common. Enlarged lymph nodes, blood in stool, diarrhea, jaundice, non healing wounds. could appear normal and actually have the disease in its system

Diagnosis  IFA (Immuno Florescence Assay) Tests for the presence of structural antigens in the cytoplasm of infected cells  ELISA Tests for the presence of FeLV p27 Tests for antigens vs. virus itself  Accuracy is higher when both tests are run

There are 6 stages of FeLV infection as follows: Stages FeLV is disseminated through the lymphoid tissue. Stage 4 – FeLV infects the bone marrow. Stage 5 - Viral-infected neutrophils and platelets are released from the bone marrow. Stage 6 – FeLV appears in epithelial tissues (e.g., salivary glandular epithelium).

Treatment Husbandry Isolation Kept indoors Vaccinated Elimination of stress Medical NO CURE Immunomodulator drugs  Acemannan  Propionibacterium acnes  Human recombinant interferon-α ★ These drugs are toxic to bone marrow. Cats should have hemograms reevaluated frequently during treatment. Limit treatment to 3-week intervals to avoid marrow toxicity. Antiviral Drugs Broad Spectrum Antibiotics Appetite Stimulants Chemotherapy Blood transfusions Fluid therapy Pain medication Therapeutic diets

Prognosis  Depends on immune status, exposure to virus, & vaccination history  70% develop immunity & are able to fight of the virus before developing the symptoms  30% that’s don’t develop the immunity are persistently viremic  Stress, or drugs that suppress the immune system, can develop a viremic breakout  IFA positive =will succumb within 6 months of detection  Average lifespan is less than 3 years

Pathologic Lesions ★ The virus causes both immune cell depletion and dysfunction which result in several FeLV-induced immunopathologic diseases and numerous secondary immunosuppressive diseases which together are the major cause of death of FeLV-infected cats Persistently veremic cats may manifest single or multiple neoplastic diseases: Lymphoma (Most Common)  Thymic lymphoma (usually in young cats <3 years old)  Alimentary lymphoma  Multicentric lymphoma  Unclassified lymphoma Lymphocytic Leukemia Erythroid and Myeloid Leukemias Fibro Sarcoma Myelodysplastic Syndrome Immunosuppression Enteropathy Infertility, Fetal Resorption or Abortion

Pathologic Lesions (Examples)

Prevention o Kittens should be vaccinated at 9 to 10 weeks of age, again 3 to 4 weeks later, and then annually. o Current commercial vaccines include a killed virus with adjuvant, killed virus without adjuvant, or a recombinant gp70 protein vaccine with an adjuvant. o The recommended site for FeLV vaccination is on the left rear thigh or tail. o If you have an infected cat in a multi-cat household, keep them separate and be persistent when it comes to cleaning! o Before vaccinating cats against FeLV, owners should consider the risks of FeLV exposure versus the potential of vaccine-related complications.

Client Education  Even though a cat may be positive for FeLV the cat does not need to be euthanized  If cat is positive these precautions must be taken:  (Keep animal indoors, Isolate from all other cats, Keep up with vaccines and see a vet if any symptoms develop)

Management of FeLV + cats  Confine FeLV-infected cats indoors to reduce their exposure to other infectious agents carried by animals, and to prevent the spread of infection to other cats in the neighborhood.  Spay or neuter FeLV-infected cats.  Feed nutritionally complete and balanced diets.  Avoid uncooked food, such as raw meat and eggs, and unpasteurized dairy products because the risk of food-borne bacterial and parasitic infections is much higher in immunosuppressed cats.  Schedule wellness visits with your veterinarian at least once every six months.  Veterinarian should pay special attention to the health of the gums, eyes, skin, and lymph nodes. A complete blood count, serum biochemical analysis, and a urine analysis should be performed at every examination.  Weight: your cat's weight should be accurately measured and recorded, as weight loss is often the first sign of deterioration.  Closely monitor the health and behavior of your FeLV-infected cat. Alert your veterinarian to any changes in your cat's health immediately.

To “Sum It Up”  Feline Leukemia Overview Feline Leukemia Overview

References   /2_Part_2/582.full.pdf /2_Part_2/582.full.pdf   Common Diseases of Companion Animals