Cat Diseases –  Feline leukemia

Cat Diseases – Feline leukemia

Feline leukemia

Feline leukemia is an infectious disease characterized by malignant lymphoma caused by feline leukemia virus (FLV) and feline sarcoma virus (FSV). 

The disease was first confirmed by Americans in 1964. Subsequently, it occurred in many countries in the world, and it is one of the important infectious diseases of cats.


Both feline leukemia virus (FLV) and feline sarcoma virus (FSV) belong to the feline leukemia virus of the retroviral family, the subfamily of tumor viruses, type C tumor viruses. The morphology and structure of the two viruses are very similar, and they are almost indistinguishable in serology. FLV is round or elliptical, has a capsule, and has a diameter of 90-110nm. The genome is composed of single-stranded RNA, which is a complete virus. FSV is a dependent virus that needs the assistance of FLV to replicate in cells. Almost all FSV isolated from sick cats contain FLV at the same time.

FLV is sensitive to deoxycholic acid, and commonly used disinfectants can inactivate it. It can be inactivated at 56°C for 30 min and at pH 4.5 or lower. The virus has certain resistance to ultraviolet light.

FLV has three serotypes: A, B, and C. Each serotype adapts to a different host. Type A FLV can only multiply on cat-derived cells, type B FLV can grow on cat, dog, cow, monkey, pig and human cells , and type C FLV can multiply on cat, dog, guinea pig and human cells.


FLV mainly infects cats, and kittens are more susceptible than adult cats. Sick cats and latently infected cats excrete toxins to the outside world through saliva and urine. Contaminate feed, drinking water, utensils and the surrounding environment. The virus is transmitted through the respiratory and digestive tracts, and can also be transmitted vertically. Pregnant female cats can infect the fetus through the uterus. Female cats during lactation can be transmitted through the digestive system. The blood contains viruses, and blood-sucking insects, cat fleas, can also become a transmission vector.


The incubation period of this disease is long, about 2 months, and the symptoms are various. It lacks specificity and is often related to the hematopoietic system. Common symptoms include weight loss, anemia, anorexia, lethargy and depression. Due to the different locations of tumors, the clinical manifestations of the characteristic symptoms of different locations.

(1) Gastrointestinal lymphoma. Intestinal lymph nodes, mesenteric lymph nodes and lymph nodes are enlarged. B-cell lymphoma occurs. The tumor mass can be palpated by touching the abdomen. Sick cats show vomiting, diarrhea, intestinal obstruction, weight loss, anemia , and jaundice. And other symptoms.

(2) Cats with multiple lymphoma are depressed. Progressive weight loss, swollen lymph nodes on the entire body, splenomegaly and liver masses can be felt by touching the abdomen.

(3) Cats with thymic lymphoma have difficulty swallowing and breathing, and the thymus tissue is replaced by tumor tissue. In severe cases, it spreads to the front of the mediastinum and mediastinal lymph nodes. Intestinal effusion, atelectasis, deep pressure in the mediastinum on both sides of the abdomen can feel the mass.

(4) Cats with leukemia have pale mucosa, mucous membranes, bleeding spots on the skin, weight loss, intermittent fever, weakness, and a significant increase in the total number of white blood cells in the blood test.


Based on clinical symptoms and pathological anatomy, a preliminary diagnosis can be made, and the diagnosis requires pathogenic diagnosis in the laboratory. Immunofluorescence antibody method can be used in laboratory diagnosis. ELISA method or take the lymphatic tissue or peripheral blood lymphocytes of sick cats, and cultivate them synchronously with the lymphocyte lines of healthy cats, and then use the neutralization test and immunofluorescence technology to identify the virus. Nowadays, FLV rapid diagnostic test strips are commonly used for diagnosis.


At present, there is no effective vaccine to prevent this disease. The feasible prevention measures are to strengthen quarantine, isolation and elimination. Establish a leukemia-free healthy cat group, strengthen feeding and management, and improve environmental sanitation.

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