Synonym: Lymphosarcoma
This is a significant cause of death in young cats. The animal remain in persistent viraemic stage for a long period and finally succumb.
Distribution
The disease is widely prevalent. 5% of healthy cats have been found to suffer in UK.
Aetiology
The disease is caused by retrovirus with a genome or RNA surrounded by a protein core and an external envelope.
Susceptible Hosts
Both house hold and free range cats used to suffer from FeLV infection.
Mode of Transmission
A cat may remain healthy but continue o excrete virus and thus transmit the infection to susceptible cats. In 30-40% cat FeLV may persist inducing a viraemic state often very young cats are infected while remain in close association with infected cats. Continuous transmission may occur from healthy carrier. Licking may spread the infection since virus may be excreted from mouth. Urine, faeces, milk may act as source of infection. Off spring may contract the infection while in the womb of the queen.
Pathogenesis
Most of the exposed cats following recovery may develop immunity. On entry the virus grows in the cell of oropharynx, then transported through mononuclear cells of blood to target tissue where viral replication takes place in a steady manner.
Virus from bone marrow will pass to other organs like upper respiratory tract, oropharynx, salivary glands through blood stream. The incubation period ranges from 4 to 30 weeks. The viral infection may persist for a short period known as transient FeLV infection. In some cats the virus may persist as healthy latent carrier known as latent FeLV infection. 85% of the viraemic cats will die within 3-5 days.
Clinical Findings
The FeLV related diseases have been classified as Malignant haemopoietic disease, Non malignant haemopoietic diseases. Malignant haemopoietic diseases include lymphosarcoma and myeloid leukaemia. Lymphosarcoma covers thymic thymic lymphosarcoma, multicentric lymphosarcoma, alimentary lymphosarcoma, lymphatic leukaemia. Myeloid leukaemia covers myeloid leukaemia, erythroleukemia, acute erythraemia.
Non-malignant haemopoietic diseases include anaemia, immuno deficiency, marrow aplasia. Anaemia may cover haemolytic anaemia and erythroid hypoplasia.
The clinical findings of Lymphosarcoma
- Young cats
- Weight loss
- Tachypnoea, dyspnoea
- Regurgitation
- Enlargement of lymphnodes
- Splenomegaly
- Tumours palpable in abdomen
- Anorexia, weight loss
- Wasting, vomiting, diarrhoea
- Pallor of mucous membrane
- Anaemia
- Intermittent pyrexia
- Anorexia, weight loss
- Pallor of mucosa
- Haemorrhage in skin mucosa
Other manifestations which are likely to be observed in FeLV are enteritis and infertility. Severe enteritis due to immunodeficiency has been reported. Enteritis may be associated with panleukopenia syndrome. Foetal resorption and absorption may occur causing reproductive problem.
Diagnosis
Diagnosis is based on clinical signs, haematology and serology.
ELISA is the most important tool for diagnosis.
Besides, virus isolation, immunofluorescence may be employed for diagnosis.
Treatment
Cytotoxic drugs are recommended for treatment. A combination of prednisolone, cyclophosphamide orally and vincristine intravenously has been suggested at 2 weekly intervals.
Control
All possible measures are to be adopted to segregate test positive cats from the negative ones. Retesting should be done at 12 weeks interval following segregation. Since the infection may spread in uterine life, breeding of sero-positive cats should not be allowed. The infection may spread through milk. Therefore such cats should not be recommended for breeding.
Vaccines if available may be used. Two vaccines are in existence in UK. They are Inactivated viral vaccine known as Leucocell-2 marketed by Smithkline Beecham, Animal Health Tad worth, Genetically engineered subunit vaccine known as leucogen marketed by Virbac Ltd. Both may afford 80-100% protection.
