FeLV

Question 1

Risk factors & transmission
- transmission routes?
- who gets it?
- environmental survival?

Answer 1

• Transmission mainly through saliva during mutual grooming, playing & sharing food/water bowls
• Transmission also possible through biting, transplacentally or blood transfusion.
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• Mainly domestic cats. Young (<1 y.o.) more likely to become progressively infected. No specific sex predilection. No breed predilection.
• Free roaming cats more at risk. Cats from areas of known high FeLV prevalence. Virus recognised as having worldwide prevalence.
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• Only infectious for minutes outside the cat and very sensitive to desiccation, disinfectants & heat. Environmental contamination not a concern
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• Not zoonotic!

Question 2

What is “provirus”?

Answer 2

the genetic material of a virus that is incorporated into and able to replicate with the genome of a host cell

Question 3

Etiology & pathophysiology – 3 possible clinical outcomes of infection

Answer 3

1. Abortive infection: strong immune
   response. Do develop antibodies. Healthy, not contagious & presumed life-long protection against new infection.
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2. Regressive infection: good immune response. Do develop antibodies. Do not shed/transmit the virus (except via blood transfusion). Infection can be reactivated after immunosuppressive/challenge event. Clinical disease uncommon.
   - Think of this as suppression/containment of virus by the immune system but not elimination!
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3. Progressive infection: poor immune response. No antibodies produced. Will likely develop FeLV associated disease.Will shed virus.

Question 4

Clinical Presentation – more specific PEX findings

Answer 4

• Gingivostomatitis & lymphadenopathy: may be signs consistent with viremia or with opportunistic infections
• Specific lymphoma-associated signs: dyspnea (mediastinal lymphoma), diarrhea +/- vomiting (git lymphoma), icterus (hepatic lymphoma)
• Specific myelosuppression-associated signs: haemorrhage due to thrombocytopenia, pallor due to non- regenerative anemia, anemia related heart murmur, tachycardia +/- tachypnea

Question 5

Diagnosis

Answer 5

• screening test / point of care test of choice:
• ELISE test for detection of FeLV antigen in serum, plasma, and blood
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  (remember, for FIV antibodies are detected)

Question 6

Confirmatory tests and when they are useful

Answer 6

• PCR to detect proviral DNA - very useful for regressive and progressive FeLV
• Immunofluorescence - for detecting intracellular FeLV antigen in neutrophils, platelets in blood smears or bone marrow
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• check with the veterinary pathology lab that services your clinic - advanced confirmatory tests are not always available? Costs may be prohibitive as well - check in advance
• N.B. ideally, blood do not cats should be screened by both FeLV ELISA and PCR testing

Question 7

Diagnosis – specific for 3 the possible outcomes

Answer 7

1. Abortive infection: FeLV antigen negative (ELISA neg) & provirus negative (PCR neg). Cats produce antibodies – true confirmation of abortive infection requires detection of antibodies but no reliable test for antibodies
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2. Regressive infection: Antigen negative (ELISA neg) or only positive for a short period. Provirus positive (PCR pos). Cats do produce antibodies but no reliable test for antibodies
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3. Progressive infection: Antigen and provirus positive (ELISA & PCR pos). Cats do not produce antibodies.

Question 8

When should testing be done?

Answer 8

• when cat is first acquired
• prior to vaccination for FeLV
• If there is concern of exposure to infected cats
• if clinical signs make you suspicious

Question 9

Implications of FeLV for your clients and other cats:
- mutli-cat households
- housing
- prevention
- etc…

Answer 9

• Every cat in a multi-cat household should be tested for FeLV…good to know status of all cats
• Do not house FeLV (+ve) cat with cats that have known contagious disease (e.g. cat flu/FURTI) or with FeLV (–ve) cats
• Commitment to diligent monitoring for clinical signs and regular check ups + re-testing as needed
• Indoor cat, enrichment of indoor space is important!
• FeLV vaccine is efficacious for multi cat households but better to keep FeLV (+ve) cats separated from FeLV(-ve) cats