The main symptoms and methods of treating leukemia in cats

Viral lesions of the immune system in cats (as in humans) are among the most severe diseases with a questionable prognosis. In humans, it is acquired immunodeficiency syndrome (AIDS). The two most common diseases in cats are feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). Both of them have a suppressive effect on the hematopoietic organs. Today we will talk about feline viral leukemia, caused by the oncogenic retrovirus FeLV.

Pathogenic effect of the FeLV virus

The leukemia virus belongs to the family of retroviruses (RNA viruses) that attack vertebrate cells. Having penetrated the body, it penetrates into the bone marrow tissue and disrupts the genetic code of immune cells - leukocytes. As a result, they can no longer fully perform their protective function. The disease has another name - leukemia, since the number of immature white blood cells in the patient's blood increases pathologically.

The main results of the destructive effect of a viral infection are as follows:

1. A blow to the immune system leads to a sharp decrease in resistance. Animals often get sick. Any interaction with pathogens can cause unpredictable complications, including death.
2. Immune cells with a disrupted genetic code are carried throughout the body by blood. This dramatically increases the likelihood of cancer.
3. There is a difficulty in making a diagnosis. The disease begins almost asymptomatically. Immune deficiency increases gradually. Serious disorders appear when the disease is already advanced. When examining sick animals, doctors cannot always associate the presence of malignant tumors with the effect of the virus.
4. With leukemia, the death of a cat usually occurs from a secondary infection that develops in conditions of weakened immunity. At the same time, there were cases when, even without the introduction of a vaccine, the initially strong immune system destroyed the invading virus, and the animal recovered.

Treatment of viral leukemia

There is no etiotropic therapy directed against the causative agent of the disease. With the help of symptomatic and supportive therapy, the course of the disease can be mitigated and life expectancy can be increased. Animals with viremia need medical attention; they are shown the following:

• maintenance therapy, including intravenous infusions - as indicated;
• good care;
• avoiding corticosteroids that suppress red bone marrow function and immunity; in special cases they can be used very carefully under the supervision of a veterinarian;
• early detection and treatment of secondary infections using antibacterial drugs: amoxicillin;
• fluoroquinolones;
• cephalosporins;
• doxycycline;

Cats with:

• severe secondary infection;
• severe anemia;
• severe exhaustion (cachexia);
• those in need of surgical care.

Routes of transmission of the virus

Individuals leading a street lifestyle and individuals with weakened immune systems are more susceptible to the disease. Cats get sick somewhat more often than cats. The virus is unstable and can survive in the external environment for about two days. In addition, it does not withstand the effects of disinfectants and is afraid of heating.

The pathogen can be transmitted through close contact between animals, through saliva, blood, breast milk, feces, urine and feces. A cat can become infected when playing together, through a shared bowl, tray, and during sexual intercourse. A transplacental (intrauterine) route of infection is also possible. Blood-sucking insects (for example, fleas) can transmit the virus from sick cats to healthy ones. Very often, animals become infected by biting and licking each other.

The disease is not believed to be airborne. The main caution must be observed if a pet goes for a walk and freely communicates with its street counterparts, who may be contagious. It's definitely worth getting him vaccinated. But the vaccine against feline viral leukemia also does not provide 100% protection. In addition, weakened animals should not be exposed to the vaccine.

Your cat's risk factors

Contact with infected cats increases the risk of FeLV infection, especially in kittens and young adults. Older cats are less likely to contract the infection because resistance increases with age.

For domestic cats, the risk of FeLV infection is very low. Cats in multi-pet households or kennels are at greater risk, especially if they share water, food, and litter boxes.

Only about 3% of cat-only households are infected with the virus, but the rate is much higher for cats that spend time outdoors. However, the prevalence of FeLV has decreased over the past 25 years due to vaccines and reliable testing.

Forms and types of leukemia

After entering the cat’s body, the virus begins to multiply in its tissues, after which it spreads along the lymphoid pathways, accumulating in the lymph nodes. At this stage, the disease is reversible; the body can still fight off the infection. When the virus penetrates the bone marrow and begins its destructive effect there, the cat will have almost no chance to be cured.

Depending on the state of the animal’s immune system, there are several forms of the disease:

1. Transient or temporary. It is typical at the very beginning of the disease, until the virus reaches the bone marrow. A strong immune system produces an effective immune response that destroys infection. This variant of the development of the disease is relatively rare. Usually no more than two months pass from the onset of the disease.
2. Latent or form of hidden carriage. This is also possible if you have a strong immune system. The virus is contained in tissues, but does not have the opportunity to multiply and become active. A cat can be a virus carrier for quite a long time - several years. She feels well, but is a source of infection for other animals.
3. Persistent or replication form of the virus. Low immunity cannot prevent the virus from entering the bone marrow. Leukocytes carry the virus throughout the body. Its content in the blood is quite high, so the signs of leukemia gradually increase. The gastrointestinal tract, bladder, skin and respiratory system are primarily affected.
4. The body's atypical response may represent a partially effective immune response. This situation occurs when, against the background of a good immune response of the body, the virus develops in a specific organ.

In addition, there are several types of leukemia depending on the location of the lesions:

1. Leukemia of the chest cavity. It is characterized by the accumulation of fluid in the chest area. The main symptom is breathing problems.
2. Abdominal leukemia has symptoms similar to those of food poisoning or intestinal infection: lack of appetite, weight loss, constipation or diarrhea, vomiting.
3. Multifocal leukemia. It has several localization sites, so diagnosing it causes particular difficulties.

Signs of leukemia in cats

The first symptoms do not appear immediately, but after several months or even years; they can be triggered by stress, other diseases, hormonal drugs, etc.

The virus, relatively speaking, loves cells that divide quickly. These are bone marrow, mucous membranes of the intestines and respiratory tract. It also promotes the formation of tumors. As a result, symptoms may vary.

If the virus has developed in the bone marrow, there will be disturbances in hematopoiesis and decreased immunity. The formation of a tumor in the intestines will lead to vomiting, diarrhea, and digestive disorders.

The development of the disease in the chest cavity is accompanied by respiratory failure and the formation of fluid in the lungs. When the nervous system is damaged, neurological deficits are observed, for example, gait disturbance.

Cats usually do not have obvious external signs indicating leukemia; the pathology can only be assumed. Typical symptoms that you need to pay attention to are gingivitis (inflammation of the gums) or other diseases that have been resistant to treatment for a long time. For example, treat diarrhea, it goes away, but if you stop giving medications, it comes back.

It is also worth paying attention to causeless weight loss (if the diet is normal and the cat has been treated for worms) or enlarged lymph nodes.

Secondary diseases caused by the virus

Persistent feline leukemia is the most dangerous, as it is characterized by active progression of the disease. Against the background of this stage, the animal’s condition quickly deteriorates. There are a number of secondary diseases that arise as a result of the action of the virus in the body. Each is caused by one of four strains of the virus (A, B, C or T).

1. Immune suppression is a consequence of all diseases leading to damage to the immune system. The animal becomes susceptible to a variety of viral, bacterial and fungal infections. This condition occurs in almost all infected cats.
2. Anemia or a decrease in the number of red blood cells in the blood. By affecting the bone marrow, the virus damages the precursor cells that produce red blood cells. This disrupts the normal process of hematopoiesis in the body.
3. Neoplasia is a pathological process leading to the development of tumors. The cause of these disorders is the integration of the leukemia virus into the genetic code of bone marrow cells. Sick animals become very susceptible to cancer. Their probability increases 50 times. But this does not always happen, but only in 15 percent of cases.
4. Other diseases. The animal's reproductive system and skin are most susceptible to the consequences of a viral attack.

FeLV infection routes

The pathogen is excreted in milk, feces, saliva, mucus, and urine. In warm conditions with moderate humidity, it lasts up to 2 days. The virus is not afraid of sunlight, but dies from disinfectants and when heated above 60C.

How can you become infected:

• when mating;
• airborne;
• through secretions;
• in utero.

Less commonly, you can introduce the leukemia virus to a cat during surgical manipulations with poorly sterilized instruments or through blood transfusions. FeLV can be spread by fleas.

There is a high probability of mass infection in shelters, nurseries, and in a flock of stray animals. The leukemia virus feels free in places where there is a concentration of animals and there is no hygiene.

Fact! There have been no documented cases of cats transmitting the leukemia virus to other animals or humans. But the possibility of FeLV reproduction in human cells has been laboratory confirmed.

Symptoms of the disease

Leukemia always causes a sharp decrease in immunity in cats. An infected animal is susceptible to frequent illnesses that are severe and have complications that tend to recur.

The remaining symptoms are associated with secondary infection and depend on its type. The following violations are almost always observed:

• frequent rises in temperature;
• loss of interest in outdoor games;
• increased drowsiness;
• poor appetite and refusal to eat;
• frequent colds, gastrointestinal problems;
• very often drooling can be observed, since the virus localized in the salivary glands causes disruption of their functioning;
• swollen lymph nodes;
• pallor of the mucous membranes.

How does feline leukemia manifest?

The decrease in the immunity of infected animals occurs gradually and asymptomatically.

Cat owners may not realize for years that their pet is dangerously ill.

Clinical signs of leukemia in cats do not appear immediately; they are diverse and resemble other pathological conditions.

Symptoms of viral leukemia:

• Weakness, increased fatigue, drowsiness;
• Lethargy, refusal of active games with the owner and relatives.
• Frequent long-term diseases of viral and bacterial nature. Relapses.
• Loss of appetite, exhaustion, refusal to eat.
• Enlarged and painful lymph nodes.
• Frequent alternation of periods of excitement with a depressed state.
• Fever. Increased body temperature above 40°C.
• Anemia.
• Pale mucous membranes.
• Jaundice.
• Gastrointestinal disorders: diarrhea, nausea, vomiting.
• Deterioration of coat condition, loss of shine.
• Difficulty breathing, shortness of breath.
• Loss of coordination of movements, muscle spasms.
• Increased salivation, stomatitis.
• Purulent discharge from the nose and eyes.
• Convulsions, seizures, fainting.
• Anisocoria – different pupil sizes.
• Reproductive problems: infertility, miscarriages.
• Tachycardia.
• Swelling of the limbs.

Important!

This dangerous disease can only be diagnosed in a clinic based on the results of laboratory tests. Don't put off visiting the veterinarian!

Diagnostic methods

Diagnosis of the disease is impossible without a detailed blood test.

1. Polymerase chain reaction (PCR) is a rapid test for the presence of the virus in the bone marrow with a high percentage of accuracy.
2. No less useful is an enzyme-linked immunosorbent test (ELISA). This is a rapid test that allows you to determine the presence of virus waste products in the blood.
3. If the diagnosis is questionable, these methods are used again after a certain period of time.
4. A general blood test will reveal disorders of the blood composition and the presence of inflammatory processes in the body.
5. An instrumental examination of organs and systems, including X-rays, ultrasound or MRI, allows us to determine deviations in their functioning, as well as the presence of tumor processes in the body.

Pulmonary lymphoma - what is it?

The lymphatic system of the lungs resembles a branched tree - its vessels penetrate the entire length of the chest and are responsible for lymph flow. There are 13 types of lymph nodes, classified into 5 groups:

1.Supraclavicular lymph nodes;

2.Upper medial lymph nodes (paratracheal, prevascular, prevertebral);

3.Aortic lymph nodes;

4.Lower mediastinal lymph nodes;

5.Root, lobar, (sub)segmental lymph nodes.

In the nodes, lymph is filtered and lymphocytes mature. Lymphomas arise in the lymph nodes.

Affected lymph nodes are often not visible or palpable. Pathological changes - enlarged lymph nodes, tissue compaction - are clearly visible on a high-resolution multi-slice CT scan or MRI. To determine the specifics of the neoplasm (normal or malignant process), the attending physician may refer the patient for histological examination. In some situations, an increase in nodes is a relative norm (after infectious and inflammatory diseases, injuries, allergic reactions), in others it indicates an oncological process. In the latter case, we can talk about lymphoma.

Since the lymphatic system is a vast network of vessels, capillaries and cavities, malignant cells can spread throughout the body, forming multiple disseminated metastases.

Treatment and prevention

To date, there is no medicine that destroys the virus, so the most effective protection against the virus is animal vaccination. The vaccination is given to kittens once. Adult animals should be vaccinated once a year. In this case, a test for leukemia is first done. If the disease already exists, but occurs in a latent form, then the introduction of a weakened vaccine can lead to activation of the virus.

Treatment of viral leukemia in cats consists of providing them with symptomatic care. But, it must be said that it can also be effective and allows you to postpone the tragic outcome for several years, by maintaining immunity at a high level. Its main points are:

1. Treatment begins with the prescription of immunostimulating drugs. Their list is compiled by the doctor taking into account the patient’s condition. To maintain immunity, the same drugs are usually used as in the treatment of HIV infection. This could be Interferon, Azidotimidine (AZT), Raltegravir.
2. High-quality, nutritious nutrition is of no small importance in maintaining a good immune status of the animal. All products must be subjected to heat treatment to eliminate the risk of various pathogens entering a weakened body along with food.

Leukemia in cats has symptoms of secondary diseases, and treatment should be aimed specifically at eliminating them.

1. Blood transfusions and antianemic therapy have a good effect.
2. If cancer has already developed due to viral leukemia, chemotherapy is used. In many cases, it is possible to stop the pathological process.
3. When a stable condition is achieved, regular visits to the attending physician are necessary. He adjusts the immunostimulating therapy and does a test to assess the animal’s health.
4. A sick cat must be kept in quarantine for life so that it cannot infect other animals. In turn, she has a risk of receiving third-party infections from surrounding animals. It is also necessary to keep her place clean, wash her bowl, tray, and toys.

Studies have shown that viral leukemia in cats is not transmitted to humans. Human leukemia is non-viral in nature. These are most likely genetic disorders of the chromosomal apparatus, living in areas with high levels of radiation.

With the active development of the virus, the prognosis of the disease is unfavorable or cautious. It all depends on how long the animal’s immunity can be maintained in good condition. But even with the most optimistic forecasts, maximum survival does not exceed four years.

Currently, we can do much more to prevent the disease than to successfully treat it. Don't forget this. Vaccinate your pets on time and do a rapid test for leukemia every year.

Features of VLK

It has been established that the causative agent of the disease can be transmitted through direct or indirect contact. It can be found in the blood, urine, saliva and milk of cats with leukemia. Fleas can also be carriers. According to recent data, feline viral leukemia is transmitted even in utero, through the placenta or when the cat bites the umbilical cords when giving birth to kittens.

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If sanitation requirements are not followed during medical procedures, the virus can spread in the body at high speed. Professionals need to be very careful :

• at the time of blood transfusion;
• when giving cats injections and other injections;
• during blood sampling.

Leukemia develops more rapidly in cats that have a genetic predisposition to the disease or an immunological deficiency. The disease destroys processes in the cat’s body such as proliferation and differentiation of hematopoietic tissue cells. Not all animals become permanently infected. They can be classified into three groups :

• Thanks to powerful immunity, about 60% of those infected are able to inactivate the leukemia virus and even completely destroy it.
• Of the remainder, 30% are considered chronically infected.
• Another 10% of cats literally “drive” the infection into some part of the body and inactivate it there. However, with prolonged stress, with the occurrence of other diseases and their drug treatment, a sharp outbreak of viral leukemia is possible.

Of animals belonging to the second group, 50% die within the first six months after diagnosis. After 3 years, the death toll will be 80%. And only 20% of cats will be able to live the allotted time, although they will be susceptible to various chronic diseases.

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The genetic resistance of a cat's body to infection with leukemia depends on the amount of antibodies in the blood. However, they are not detected in all cases. The leukemia virus in cats can be characterized by the following :

• Decreased bone marrow function. Anemia develops and spontaneous bleeding appears.
• Suppression of immunity. Infectious peritonitis and other diseases are possible.
• The course of pregnancy with leukemia is complicated. Resorption of fetuses, frequent stillbirths, and repeated abortions (miscarriages) occur.

The leukemia virus begins to spread throughout the body, settling in the tonsils of the pharynx. The intensity of its attacks depends on the cat’s immunity, its age, and the dose of the virus received. It first attacks lymphoid tissue, then bone marrow.

What types of lymphomas are there?

Primary lymphomas are usually divided into two large groups:

• Hodgkin's lymphomas/lymphogranulomatosis (Hodgkin's disease, Hodgkin's lymphomas),
• Non-Hodgkin's lymphomas (lymphosarcoma, NHL).

According to the National Medical Research Center of Oncology named after. N.N. Blokhin, in Russia the incidence of non-Hodgkin's lymphomas is 1.5-3 times higher than the incidence of lymphogranulomatosis.

The difference between these lymphomas becomes clear after morphological examination of a tissue sample (biopsy). In Hodgkin's disease, large mutated Berezovsky-Sternberg-Reed cells are found in the affected lymph nodes. Hodgkin's lymphomas have a more aggressive course with pronounced symptoms, but they are easily treatable.

Lymph nodes affected by Hodgkin's disease are most often located above the collarbones, in the neck, armpits, and mediastinum.

In addition to B-lymphocytes, non-Hodgkin's lymphomas also affect T-lymphocytes. The disease usually occurs without significant symptoms and is difficult to treat. But first you need to correctly determine the type of non-Hodgkin lymphoma - the current classification consists of 30 names, including:

• chronic lymphocytic leukemia;
• T-cell leukemia;
• follicular lymphoma;
• diffuse large B-cell lymphoma;
• mycosis fungoides Sézari et al.

Lymphoma of the lungs on CT

Signs of pulmonary lymphoma are especially pronounced in the fourth stage of the disease, when the disease affects the respiratory organ. On a CT scan, enlarged lymph nodes will be visible, forming chains and conglomerates. In this case, the patient may also experience pulmonary edema. However, the high resolution of CT makes it possible to detect lymphoma at an early, first stage.

On CT scans, lymphomas, like any lumps, are visualized in a relatively lighter color. Normally, the airy pulmonary parenchyma is almost uniformly dark in color. Sometimes there are several such compactions and they are disseminated. The contours of the lymphoma are clear and even. Areas of “frosted glass” are found around pathological lesions.

Is lung lymphoma cancer?

Not always. However, lymphomas primarily include malignant neoplasms of the lymphatic system, which are formed due to the uncontrolled accumulation of pathologically altered lymphocytes. An exception may be indolent lymphomas. They do not require treatment, but monitoring them is also important. If the patient exhibits the symptoms described above (temperature, fever, chest pain), then examination and treatment of such lymphomas must be carried out.

Malignant lymphocyte cells have a different shape from “regular” cells and represent a fatal “failure” in the functioning of the body. Such cells have completely different functions - they produce a huge amount of proteins and toxins, but are not destroyed by cells of the immune system as hostile.

Lymphomas are not always the primary site of cancer. A pathologically enlarged node or a group of nodes (disseminated or localized in one place) is often a consequence of metastatic processes. This occurs due to the fact that the lymph node acts as a filter and accumulates malignant cells that have separated from the primary affected organ. In this case, it is important not only to identify the lymphoma, but also the primary focus. Enlarged lymph nodes of the lungs may indicate cancer of the lungs, breast, mediastinum, stomach, that is, organs located in close proximity.

The diagnosis of a benign or malignant neoplasm can be clarified based on the results of a biopsy (histological examination of a tissue sample). The patient also undergoes clinical and biochemical blood tests. On a CT scan of the lungs, doctors identify a tumor, can assess its size, the extent of enlarged lymph nodes, but it is not possible to make an accurate conclusion about the type of tumor without tests.