What is leukemia in cows, its symptoms and signs

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Leukemia in cattle is caused by a special type of virus. The activity of the pathogen leads to an excessive increase in the size of the cells of the hematopoietic organs. Leukemia is common in cows.

Leukemia in cows

Today, the disease cannot be treated, and the only control measure is regular examination of livestock. Do vaccinated cows have leukemia? Could this be a poor grooming problem? The answer to these questions can be obtained by carefully studying all the information regarding the disease and its causes.

Causes of leukemia in cows

Leukemia in cows is caused by a representative of oncornaviruses. This type of virus provokes malignant degeneration of healthy cells and tumor growth. The site of localization of the pathogen is leukocytes, more specifically, the fraction of lymphocytes.

The main reason why blood cancer appears in domestic horned animals is the acquisition of new animals from dubious breeders, as well as neglect of preventive measures.

How is leukemia spread in cows? It happens:

1. When animals come into contact, through biological fluids (blood, milk, semen). From bulls to heifers, the virus is transmitted with sperm. Calves become infected from a sick mother in the womb or after birth through milk. Leukemia in cows is easily transmitted in herds where there is no inseminating bull. During the hunting period, cattle jump on top of each other, as a result of which the skin may be disturbed, and this is the risk of infection. If one animal is infected with the bovine leukemia virus, it is transmitted through the blood to the second.
2. Through the bites of blood-sucking insects. Mosquitoes and other blood-sucking animals are also dangerous. It is impossible to cope with this problem, there is no panacea.
3. Through inventory for veterinary and zootechnical processing. Veterinary services very often use non-sterile instruments for mass inspection of the herd, vaccination, etc. The first signs and symptoms will not appear immediately, and this threatens the spread of the disease to other individuals in the herd.

The disease can occur in two forms: sporadic and enzootic. Enzootic leukemia is characterized by a long latent period of more than 3 months. The disease affects adult cattle. Young animals are susceptible to sporadic leukemia. This disease develops very rarely.

The development of the leukemia virus in cows is not influenced by climatic conditions, therefore, infection of cows is common in different countries. A higher risk of getting the disease is observed in Africa, India, etc.

Stages of leukemia in cows

Bovine leukemia affects cows, regardless of their color and size. The disease develops in three stages:

1. Hidden (incubation). It starts from the moment the virus enters the animal's body. Outwardly, the disease does not manifest itself. The stage can last for a very long time if the immunity of the pets is strong.
2. Hematological stage. It is characterized by a change in the composition of the animal's blood.There is a rapid and constant increase in the concentration of leukocytes (leukocyte). Bovine leukemia can be diagnosed with a blood test. The first symptoms also appear: disruption of the gastrointestinal tract.
3. Tumor. The growth of tumors of the hematopoietic organs is observed. The tumor stage can occur only 5 years after infection.

In the early stages, the causative agents of leukemia in adults can be found in milk, so it is important to regularly donate it for research to a microbiological laboratory, to follow the rules for keeping animals. The disease is transmitted to healthy individuals very quickly. Timely identification will help to avoid significant losses of livestock, treatment has not yet been developed.

Symptoms of leukemia in cows

Signs of animal leukemia do not appear in the early stages. Symptoms are noticeable at a late stage. A change in the composition of the blood leads to serious disorders in the body.

To suspect that a cow is sick with leukemia, the following signs will help:

1. Weakness.
2. Rapid, heavy breathing.
3. Digestive problems.
4. Exhaustion.
5. Swelling of the dewlap, abdomen, udder.
6. Lameness in the hind legs.
7. Severe swelling of the lymph nodes.
8. The appearance of visible tumors in different parts of the body.
9. Exophthalmos (bulging), a rare symptom.

Sick animals poorly assimilate proteins, fats, carbohydrates, vitamins and minerals from feed. This becomes the cause of exhaustion, weakness. Also, the animal gives less milk. When signs of malaise appear, you need to isolate the animal, conduct an immediate veterinary examination, and do blood tests. Blood cancer in cattle is incurable. Abnormal white blood cells do not perform a protective function, so animals will be susceptible to various infectious diseases.

What can and cannot be done when a disease is detected in livestock?

Diagnosis of leukemia in livestock

The diagnosis of bovine leukemia is made only after a number of laboratory tests. Tests will help determine the presence of the disease:

1. Indirect serological tests - immunodiffusion reaction (RID), enzyme-linked immunosorbent assay.
2. Direct detection of the virus in biological fluids is a polymerase chain reaction.

Diagnostics using RID and ELISA allows detecting antibodies to BLV in the biological fluid. The causative agent lives in the animal's body for life, integrating its genome into the blood cell. The immune system starts producing specific antibodies a few days after infection. They are constantly present in the blood of a sick individual.

PCR diagnostics allows to detect the RNA of the causative agent of cattle leukemia in the blood. This most sensitive and accurate method has not yet become widespread due to the high cost of reagents and equipment. The PCR result does not depend on the age of the animal, in contrast to the RID tests, therefore, using this method of analysis, it is possible to identify a sick calf. RID is used only for adults. In the early stages, it is difficult to detect infection with immunological tests. The body has not yet developed response molecules. PCR, on the other hand, allows you to detect infection from the first days. To quickly identify infected animals and improve the health of the herd, it is advisable to use a complex of RID, ELISA and PCR studies.

Is the bovine leukemia virus dangerous for humans?

Bovine leukemia is a serious and incurable disease. The appearance of one sick individual in the herd can lead to a fall in the entire livestock population. Is the disease dangerous for humans and is leukemia dangerous for young cows? This is the most common question doctors are asked. Humans are not susceptible to existing strains of BLV. Until now, no cases of human infection with cattle leukemia have been identified in medical practice, but still doctors still cannot answer for sure whether animal leukemia is dangerous for humans, everything is very individual.

Viruses are very flexible, mutate quickly, adapting to drugs and environmental conditions, so there is no guarantee that tomorrow there will not be a new VLCV strain that will pose a danger to humans.

A sick cow can infect goats and sheep with leukemia. The infection is transmitted through milk.

Can you drink milk or eat meat from a sick cow?

Cow leukemia is not dangerous to humans. But you should refrain from eating milk and meat: an infected specimen gives dangerous products. During the development of cancer, harmful substances and toxins accumulate in the animal's body. You can not get sick with leukemia, but get an ailment from harmful toxins. The pathogen dies during heat treatment, and there is no way to get rid of toxins, therefore it is better not to eat meat and not drink milk from cows with leukemia, not to give it to children.

If the disease was detected in the first stage, the animal is slaughtered on a general basis.

Sick cows with a hematological stage of infection are killed in a slaughterhouse. The meat undergoes a mandatory examination, the veterinarian gives recommendations on its further use. The meat can be allowed to be eaten in the form of sausage or stew. Unsuitable raw materials are disposed of.

Prevention of leukemia in cows

Treatment of leukemia in cows is not carried out even in the most developed countries. Infected individuals are given for slaughter. However, cattle disease can be prevented. Leukemia prevention measures were developed for large and small farms back in 1999.

To prevent infection of livestock with leukemia, you need to follow these rules:

1. You can buy and bring into your farm only young animals from healthy bulls and cows. There should be no leukemia patients in their pedigree.
2. New animals are kept for the first 2 months in premises isolated from the main herd. During this time, the animals must be examined by a veterinarian twice and blood taken for PCR. If negative test results are obtained, the cattle are brought into the general herd. If sick animals are found among the young, they are sent for fattening. The rest are double-checked by RID and ELISA, introduced into the general herd, if the analyzes both times gave a negative result.
3. RID-positive animals should be formed into a separate herd and kept isolated from others. Such animals go to fattening. Calves of the last calving from RID-positive cows must be checked by the PCR method. If the answer to the test is in the affirmative, the animals are fed. Older offspring are used depending on the advice of the veterinarian.
4. In large farms, hardware milking, veterinary treatment, etc. you need to start with healthy cows.
5. It is important to number the calves with liquid nitrogen, dehydrate them thermally or chemically, so as not to infect them through instruments.
6. Preventive measures should cover all livestock.
7. Blood for analysis is taken from bulls-inseminators 4 times a year.
8. Pregnant cows are examined two months before and two months after calving.

It is also important to ensure the sanitary conditions for keeping animals. It is necessary to handle milking machines, all veterinary equipment. In the premises for calving cows in large farms, special sanitary conditions must be created. Free mating in a herd of cattle should not be allowed. If there is no inseminating bull, sperm for artificial insemination of cows should be bought only from verified people and submitted for research to a microbiological laboratory.

Cow leukemia is a serious disease. Pets are infected by contact with patients, through veterinary equipment. Sick individuals and calves are slaughtered, no treatment is performed. Cow leukemia is dangerous for sheep and goats; humans are not susceptible to the virus. Milk from infected individuals should not be consumed; in rare cases, it is possible to eat meat, but only after a veterinary examination.Regular preventive blood testing of livestock will help maintain a healthy livestock.