Leukemia in cats (viral leukemia): symptoms, pathology diagnosis and treatment

Viral leukemia in cats is one of the most dangerous incurable diseases caused by a retrovirus. The disease has a latent, sluggish form without manifestations until the terminal phase begins. Viral leukemia, together with immunodeficiency and infectious peritonitis, is one of the most dangerous diseases of cats with high infectivity and mortality.

In addition to the standard name, the disease is also called lymphosarcoma, blood cancer, hemoblastosis, viral leukemia and leukemia. In tests, leukemia is abbreviated as FeLV or VLK.

Owners of a cat with leukemia should take into account that if the disease is detected at an early stage, then with the help of supportive therapy selected by a veterinarian, their furry pet can live a long and happy life.

Why is it dangerous to neglect treatment for leukemia?

Lack of treatment is fraught with the development of the disease and its accompanying pathologies, which lead to death. An animal that does not receive veterinary care develops:

• anemia;
• spontaneous bleeding;
• chronic cystitis;
• constant low-grade fever;
• bacterial infections;
• viral respiratory diseases;
• peritonitis;
• ascites;
• toxoplasmosis;
• autoimmune glomerulonephritis;
• stillbirth;
• damage to the mammary glands in females;
• miscarriages;
• fetal resorption and fading kitten syndrome;
• sarcoma of the lymphatic system.

A pregnant cat with leukemia will give birth to already infected kittens, which usually do not survive due to the body’s lack of strength to fight the virus. Therefore, cattery owners should definitely examine their cats.

How does it manifest?

Viral leukemia can be asymptomatic for months or even years. The disease can become active due to stress, decreased immunity, and other diseases. Symptoms are varied and nonspecific, depending on the subgroup of the virus. The most common are the following:

• frequent infections of the respiratory tract, nose, eyes, ears, skin, often difficult to treat
• viral infections in animals vaccinated against them
• lethargy
• gingivitis (inflammation of the gums)
• stomatitis (inflammation of the mouth)
• loss of appetite
• progressive weight loss
• abortions and stillbirths in cats
• enlarged lymph nodes
• frequent persistent diarrhea
• anemia (low red blood cell count)
• leukemia, often progressing to leukemia
• “fading kitten syndrome”: newborn kittens die within a few weeks
• lymphoma (benign tumor of lymphoid tissue)
• lymphosarcoma (malignant tumor of lymphoid tissue)

Which cats can get leukemia?

All cats are at risk. Stray animals, domestic animals, young and old, purebred and mixed-breed animals are susceptible to the disease.

Why, then, are they not all carriers of the virus? The fact is that the virus is quite unstable to external influences. In the external environment, it most often dies within a couple of days. It is dangerous from sunlight, ultraviolet rays, low and high temperatures. It is vulnerable to disinfectants and alcohol-containing products. Nevertheless, it is incorrect to even talk about the relative safety of animals.

Reference! Cats, due to their lifestyle, are more often susceptible to the disease (fights, including for the right to mate with a cat in heat).

Definition of disease

In veterinary medicine, feline viral leukemia is usually called a disease characterized by a polysymptomatic course. It can manifest itself as immunodeficiency syndrome, the formation of malignant tumors, pathologies of various organs and systems, fetal death and miscarriages. Sick pets become more susceptible to other infections, which significantly distort the clinical picture of the disease and make diagnosis difficult.

Leukemia in cats occurs after the RNA-containing retrovirus FeLV enters the body and causes a significant decrease in immunity, provokes the development of malignant tumors in the spleen and red bone marrow. A very important factor is that the feline leukemia virus FeLV is not dangerous to humans and other animals, even with direct contact with the source of infection.

Note! This viral pathology should be distinguished from classic feline leukemia, which is an oncological disease with characteristic mutations in red bone marrow cells and the formation of cancer cells. Such leukemia most often develops under the influence of large doses of radiation, when carcinogenic substances enter the animal’s body, as well as hereditary genetic factors. In this case, the disease is not contagious to other cats and is manifested by a set of certain clinical signs.

The most susceptible to feline leukemia virus are kittens under 8 weeks of age born to unvaccinated mothers. Intrauterine infection is also possible. In both cases, the pathogen immediately enters the bloodstream, quickly spreads throughout all tissues of the body and provokes death.

The risk group also includes cats over 7 years of age and stray animals. A large percentage of sick young cats is explained by their activity during the period of sexual heat, when pets run away from home and come into contact with infected relatives.

Methods of transmission of the virus

The virus is highly contagious - the ability of the infection to be transmitted from sick animals to healthy ones. It is transmitted from a sick animal to a healthy one under the following conditions:

• contact with the host’s saliva, urine, feces, or secretions from his nose or eyes;
• biting during a fight or play;
• through shared dishes, toys, beds;
• sexually;
• in utero from mother to kittens (as a rule, such babies do not survive);
• through flea bites;
• at an exhibition when using common things or being close to a sick colleague;
• after the owner visits the house where the leukemic cat lives, or a shelter, without changing clothes;
• in a clinic where instruments and tables are not thoroughly sanitized after each patient.

The greatest prevalence of hemoblastosis is observed in crowded cat prides, in so-called granny apartments, in shelters, as well as in basements where homeless individuals live.

Detailed lecture from a veterinarian about leukemia in cats:

What symptoms indicate the disease

The leukemia virus is secretive for a long time. The following signs may indicate that your cat has FeLV:

• exhaustion, lethargy;
• fever, brick-brown urine;
• overexcitation or drowsiness;
• pallor, swelling of the mucous membranes;
• loss of movement coordination;
• skin pathologies (wounds, scabs around the claws).

A cat with FeLV symptoms has difficulty breathing, has difficulty clotting, and has cold limbs and skin. Fainting, convulsions, and disruption of the gastrointestinal tract are observed.

Upon examination, the veterinarian diagnoses a tumor, anemia, paralysis, nodules in the intestines, enlarged lymph nodes, fluid in the pleural and abdominal cavity, rhinitis, sinusitis, peritonitis, edema, etc.

The acute course of the leukemia virus occurs without enlargement of the spleen and lymph nodes, or it is insignificant. Chronicization of the process results in the proliferation of lymphoid tissue and metastasis. FeLV is a systemic pathology, manifested by a complex of symptoms.

What causes the development of leukemia and what is its danger

The causative agent of the disease is an RNA-containing oncogenic retrovirus, which invades blood cells and destroys their genetic code. The Latin name is Feline leukemia virus. It was identified by scientists in Glasgow in 1964. Scientists have established a connection between cases of cancer of the blood and lymphatic system in cats with the detection of strains of this virus in their blood.

The virus is dangerous due to its oncogenicity and changes in blood composition, reducing the resistance of the cat’s body, and provoking secondary diseases. It begins its activity in the tonsils and lymphatic tissues of the nasopharynx, gradually spreading to the lymph, circulatory system, and brain.

Immune deficiency increases unnoticed. When the process spreads to the bone marrow, it is too late to fight, since the affected bone marrow produces more and more replicas of the virus along with blood cells, and leukocytosis progresses. Death usually occurs from diseases associated with hemoblastosis.

Highest Magnitude

Viral leukemia (leukemia, leukemia, lymphosarcoma) is a tumor disease of the hemolymphopoietic system of cats, characterized by malignant proliferation of hematopoietic tissue, disruption of the maturation process of blood cells with predominantly intensive formation of young cell forms and manifested in the form of syndromes.

The causative agent of feline leukemia is recognized to be an RNA-containing virus of the family Retroviridae, subfamily Oncornavirinae, genus of oncovirus, type C, species of feline oncovirus. Abroad it is called FeLV. The pathogen exists in two forms - endogenous (non-pathogenic) and exogenous (pathogenic).

Symptoms of leukemia in cats

The disease is insidious in that it does not appear immediately, but when the number of leukocytes in the blood exceeds acceptable limits. In this case, helping your pet is very difficult, if possible at all.

Therefore, it is necessary to show your furry puppy to the veterinarian twice a year so as not to miss the first symptoms of the disease.

VLK in cats manifests itself with the following symptoms:

• drowsiness;
• lack of interest in games;
• frequent rises in temperature;
• loss of appetite;
• lethargy;
• salivation;
• frequent colds, cystitis;
• digestive problems;
• enlarged lymph nodes;
• discharge from the eyes and nose;
• bulging eyes;
• pallor of mucous membranes.

The symptoms are nonspecific, and the owner will not be able to independently figure out what is bothering his pet. By self-medicating, you can waste time and ultimately lose your pet.

Blood test for feline leukemia

The most accurate way to make a diagnosis. Typically, the analysis is carried out twice to eliminate the risk of error. The study is carried out in laboratory conditions. The following deviations in indicators are observed in infected animals:

• increased number of neutrophils;
• acceleration of ESR sedimentation;
• increase in the number of leukocytes.

A cat is considered healthy if tests taken 12 weeks apart are negative on both occasions.

Life expectancy of a cat after infection

How long a cat can live after contracting viral leukemia depends on its immunity. Typically, it takes 3 to 10 years from infection to death. The incubation period ranges from four days to eight months.

Unfortunately, 90% of infected animals die in the 4th year of the disease. This high mortality rate is due to the fact that obvious symptoms appear 3 years after the cat is infected.

With good care, the animal remains a carrier of the infection for a long time, but does not get sick, and clinical signs of the virus do not appear. However, carrying the virus poses a danger to other cats.

Causative agent of leukemia

Feline viral leukemia can also affect other animals. The causative agent of the disease is oncovirus. It belongs to the group of retroviruses. When infected, tumors can form. Viruses are spherical in shape. Leukemia cells quickly lose activity at high temperatures. When heated to 70 degrees Celsius, the virus is deactivated after 30 minutes. If the temperature rises to 85 degrees, leukemia cells die within 10 seconds. They remain active for about 3 years. The virus is sensitive to ether and chloroform.

Can a person get infected from a cat?

Numerous studies prove that it is impossible to become infected with leukemia from cats . In the human body there is nothing for it to “catch onto”, since the DNA of a cat and a person do not have identical areas vulnerable to the virus. In addition, human leukemia has a completely different, non-viral nature.

Feline leukemia is not dangerous for dogs either.

Therefore, you should not be afraid to take such an animal into your home as your only pet or in the company of a carrier of the same virus.

Types and forms of leukemia

An animal may have one or more retrovirus strains: A, B, C or T.

Depending on the state of immunity, leukemia in cats can occur in several forms:

• Transient (temporary). The initial period of the disease, until leukemia affects the bone marrow. At this stage, in rare cases, a strong immune system can develop a powerful response and destroy the pathogen completely. Such an animal receives lifelong immunity against viral leukemia. Typically, no more than two months pass from the onset of the disease, and these cats do not become a source of danger to others.
• Latent . This variety can occur when the immune system is strong. Replications of the virus are already present in the tissue structure, but the infection cannot multiply and become active. The animal remains a carrier, it may feel great, however, it poses a danger to healthy fellow tribesmen.
• A persistent or replication form of a viral organism. The weakened immune system no longer resists the penetration of the virus into the bone marrow structure. Signs of leukemia increase, primarily anemia. Particular harm is caused to the gastrointestinal tract, skin, bladder, and respiratory system.

Leukemia can be differentiated by type of localization:

• Thoracic leukemia is characterized by the accumulation of fluid in the chest area, due to which the animal becomes increasingly suffocated. Differential analysis with the wet form of viral peritonitis is required due to the similarity of symptoms;
• abdominal is characterized by damage to the gastrointestinal tract and resembles an intestinal disorder or jaundice; constipation, dehydration, and cachexia also develop;
• multifocal affects several organs at once and has a very poor prognosis due to the difficulty of diagnosis.

Clinical picture

The initial stage of the disease lasts up to 16 weeks. During this period, the cat's lymph nodes enlarge. This stage can lead to the development of the disease in three ways.

In the first case, viral cells are present in saliva and blood for a short period of time, namely up to 12 weeks. The development of infection ends with the cat’s complete recovery. She gains lifelong immunity. The animal is not a carrier of the disease.

In the second case, the virus remains in the blood and saliva for more than 12 weeks. The disease develops and progresses. Over time, the animal dies.

In the latter case, the virus disappears from the blood and saliva after some time. However, it remains in the bone marrow, spleen and lymph nodes. Such animals release infection into the environment. Over time, clinical symptoms may develop. In this case, the infection multiplies and suppresses the pet’s immune system. Secondary diseases develop, namely toxoplasmosis, peritonitis and respiratory diseases. Over time, the animal may also develop anemia. Bleeding may occur. The cat has a painful tumor or enlarged lymph nodes.

Diagnostics

In order to confirm or exclude viral leukemia, and if confirmed, determine its type and form, the veterinarian performs a series of tests:

• clinical blood test - to determine the level of leukocytes in the blood, erythrocyte sedimentation rate, the presence of anemia;
• PCR - polymerase chain reaction - study of peripheral blood;
• immunofluorescence blood test , which allows you to detect antibodies to the virus and determine its type;
• ELISA is an enzyme-linked immunosorbent assay that detects the presence of antibodies and antigens to the virus in the blood.

Attention! If, while symptoms persist, all tests for VLK are negative, it is too early to calm down. It is necessary to retake them after three months and conduct a differentiated study, since the same symptoms may indicate completely different diseases.

Today, veterinary clinics are increasingly doing rapid tests for leukemia ; they provide a high degree of reliability, but it is better to play it safe and conduct a comprehensive analysis.

It also doesn’t hurt to conduct ultrasound and x-ray studies, which can help identify the presence of malignant neoplasms and see abnormalities in the functioning of internal organs.

In some cases, the following are recommended for diagnosis:

• biopsy;
• colonoscopy;
• gastroscopy;
• laparoscopy.

These are invasive or minimally invasive tests and are done under general or local anesthesia.

Diagnosis and therapy

So, it is possible to more or less accurately determine the presence of leukemia only in a well-equipped clinic based on the results of a blood test, biopsy, serological reactions and other specific methods. A simpler diagnosis will not yield anything meaningful. It is important to note that tests to detect the disease must be carried out twice. If the result is positive both times, everything is bad. What about therapeutic activities? Is there any salvation from this terrible disease? Unfortunately, there is still no effective treatment. Symptomatic therapy is used, which helps relieve particularly severe symptoms and prolongs the life of the animal, but, unfortunately, it is still impossible to make it healthy. In particularly severe cases, it is recommended to euthanize the cat.

Treatment of viral leukemia

It is not yet possible to completely cure a cat from leukemia. But timely symptomatic therapy will significantly alleviate the pet’s condition and prolong its life. The selection of drugs is carried out by a veterinarian strictly individually, depending on the condition, tests and symptoms of the patient.

Modern veterinary science suggests acting in two directions in cases of deteriorating health:

1. Stimulation and strengthening of the animal's immunity . The following proven drugs are used:

• Raltegravir.
• Feliferon.
• Interferon.
• AZT.

Antibiotics and vitamin complexes are also used.

1. Symptomatic therapy:

• with the help of medications, symptoms of diseases developing due to decreased immunity and inhibition of hematopoiesis are relieved;
• a good but temporary effect is achieved by blood transfusion , this procedure will have to be repeated every 2 weeks; if oncology is diagnosed, chemotherapy (in particular, Vincristine), usually in this way it is possible to stop the pathological process.

In addition, owners will have to reconsider their approach to feeding their pet. Food must be complete and of high quality, heat-treated to prevent germs, bacteria and other pathogens from entering the weakened body of a pet.

A cat diagnosed with viral leukemia will have to be kept in quarantine for life , contact with other cats must be prevented, and its bed, dishes, toys, and litter tray must be kept clean. If there are other cats in the house, then after contact with the carrier you need to thoroughly wash your hands and, if possible, change clothes. It is useful to regularly quartz the room in which the carrier cat lives (during quartzing, the animal must be removed from the room).

Important! Remember that euthanizing a cat is a last resort. Never give up in the fight against the disease, even without resorting to treatment.

Prevention

You should not allow your pet to come into contact with stray and unexamined fellow pets, place it in dubious pet hotels and in unverified foster care, or use other people’s toys, trays, treats, food, bowls, beds, or medicines.

After the death of the previous cat from leukemia, it is recommended to get a new companion no earlier than 2 days after the death of the sick cat and only after cleaning the apartment. It is better to purchase new bowls and trays.

But the best way to protect your pet from viral leukemia is timely vaccination , which must be preceded by a carrier test. Kittens are vaccinated at the age of 2 months and repeat this procedure annually. The vaccine does not kill the infection, but increases the body's resistance to the virus and has a cumulative effect. Therefore, it is important not to forget to vaccinate your pet.

Viral leukemia is one of the most dangerous pathologies in cats. The prognosis for the disease is unfavorable, but still, in our time, lymphosarcoma is not a death sentence, so it is important to recognize VLK at the initial stages of development using comprehensive diagnostics. A timely visit to a specialist will help improve the quality of life of your furry cat and extend his days. To prevent infection, it is necessary to follow preventive measures and pay attention to the general condition of the animal.

Lymphosarcoma of the thymus

As noted above, viral leukemia in cats (its symptoms are very diverse) has many elements in its structure, among which thymus lymphosarcoma occupies a special place. The most important sign of the disease are tumors of significant size in the anterior mediastinum. The lymph nodes become larger, however, the spread of the tumor mass to other nodes is practically excluded. In addition, unhealthy cells can be observed in the blood extremely rarely.

When studying the clinical signs that accompany leukemia in cats (symptoms and treatment of the pathology are interrelated) of this form, one should highlight the enormous size of the tumor after just half a month, which causes rapid breathing, as well as shortness of breath and intolerance to physical stress. In addition, there may be difficulties in swallowing due to compression of the esophagus, as well as a dull heartbeat. It is important to note that this form of leukemia is most often observed in cats between two and three years of age.

Leukemia in cats (symptoms discussed above) can also manifest itself in the form of multiple lymphosarcoma. In this case, it is appropriate to involve tissues of the entire body in the pathological process. Malignant lymphoid cells undergo infiltration, causing the lymph nodes to become significantly enlarged. Moreover, this excess of size is bilateral in nature. In addition, the spleen and sometimes the liver enlarge.

With multiple lymphosarcoma, moderate anemia occurs (in approximately 50 percent of cases). But tumor cells can be observed extremely rarely in the blood (about 20% of all situations). Treatment of leukemia in cats with multiple lymphosarcoma is carried out only after confirmation of the diagnosis (through lymph node biopsy).

In the case of lymphosarcoma of the alimentary type, malignant masses are located in the walls of the digestive system. In addition, they can spread to the misenteric lymph nodes. The tumor is often localized in the large, small or cecum. Less commonly, it is located in the stomach or rectum. Detection of diffuse infiltration of a significant part of the intestine is extremely rare.

Among the clinical signs of the disease in question, significant weight loss should be noted, usually leading to anorexia. If the tumor mass clogs the passage of the small intestine, vomiting is one hundred percent likely to occur. But diarrhea occurs when a tumor has developed in the small intestine or in its lower part in a diffuse manner.