Feline viral leukemia: the best battle is the one avoided

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.

What is leukemia (FeLV)

Viral malignant disease of the circulatory system of the cat family - FeLV. Otherwise it is referred to as cancer or a malignant tumor that can be transmitted to other species and destroy the weakest animals with immunity.

Feline leukemia virus (FLV) belongs to the same group as HIV. Causes serious complications and exposes the body to weak protection against other diseases due to weakened immunity:

• viral, bacterial, fungal, parasitic infections;
• tumors;
• bone marrow diseases.

A cell infected with a retrovirus.
The dangerous effect of the virus awakens long after infection, cannot be treated, but can be prevented through vaccination.

In the external environment, the virus loses resistance and dies after two days. It is vulnerable to sunlight, low or high temperatures, ultraviolet rays, and is defenseless against disinfectants and substances containing alcohol.

FeLV provokes the appearance of malignant tumors, which leads to death

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.

Which cats can get leukemia?

Any representatives of cats are susceptible to infection with FeLV: domestic, stray, purebred, domestic, young, elderly, mestizos.

The virus is easily transmitted from an infected individual to a healthy one in the following cases:

• games, fights, bites with each other - simple contact or fights, bites, scratches;
• sexually;
• through eating, drinking from the same bowl, using the same toys or beds;
• in utero - from mother to kittens;
• through flea bites;
• in the clinic after doctors saw a leukemic cat without further treatment of the table.

Fights and contacts with other cats on the street
There are a lot of ways to transmit a dangerous virus. This incident can occur even if the owner had contact with an infectious cat, for example, in a shelter or at an exhibition.

Infection is transmitted through any contact of a cat with saliva, blood, urine, discharge from the nose or eyes, or feces of a sick animal, even if any of the above gets on the fur of a healthy pet.

Transmission routes

The leukemia virus can be transmitted in different ways. It has been established that in the hereditary material of cats there are more than 100 types of copies of endogenous (internal) viruses. In the course of numerous studies, scientists have discovered that under the influence of certain conditions, these viruses begin to be independently released in the body of animals, which ultimately causes the development of chronic leukemia.

However, this phenomenon occurs quite rarely. Basically, leukemia is provoked by exogenous (external) viruses that live in the external environment. This type of viral organism was identified back in 1964, during the same period it was found that leukemia in cats has a viral course and can affect all cats.

So how is this disease transmitted? The following transmission routes are distinguished:

• contact through biting and licking;
• Infection can occur through shared drinking and eating cups, as well as the female's milk. The virus can enter through a shared toilet;
• sexually;
• through the placenta in utero;
• through blood. Typically, infection occurs through untreated medical devices and blood transfusions;
• The leukemia virus can be carried by fleas.

Note! A pathogenic pathogen of viral pathology can maintain active viability in an open environment for 48 hours. It can be released along with saliva, nasal mucus, urine, feces, and milk.

This pathology often affects street cats. The most unfavorable areas, in which there is a high probability of infection, are considered to be those in which there are many homeless and stray animals.

Veterinarians say that leukemia only affects cats and cannot infect other animals. There is no scientific evidence that the pathogen can be transmitted to humans. However, laboratory studies have established that the virus is capable of developing in human cells.

What causes the development of leukemia and what is its danger

Infection of vertebrates with a retrovirus occurs in the cytoplasm of the cell (a viscous internal environment bounded by a membrane), where the synthesis of the viral DNA genome begins. Retroviruses, after introducing their genome into the host's chromatin, remain there forever and are transmitted genetically to offspring.

The correct transmission of information in a cell has the sequence: DNA → RNA → protein (transcription process). The protein cannot change genetic information. Retroviruses have an enzyme that changes this sequence, where genetic information is encoded in RNA.

When it enters a healthy body, this virus synthesizes host DNA into viral RNA, which then becomes normal DNA and is new genetic material for the subsequent development of the virus inside the cell.

Viral RNA, viral enzymes

The effect of the virus begins with activity in the lymphatic tissues, tonsils, nasopharynx, then spreads to the circulatory system and affects brain cells.

What happens after infection?

After entering the cat’s body, the virus enters (directly or through the bloodstream) into the tonsils of the pharynx, where its primary replication (reproduction) occurs in macrophages and B-lymphocytes. Then the affected cells enter the bloodstream, where they spread throughout the body and infect lymphoid tissues. In approximately 20% of cats, an adequate immune response occurs at this stage, and the virus is completely eliminated from the body.

If this does not happen (reduced immunity, young or old age, stress), the virus attacks the bone marrow and cells of the immune system (neutrophils, lymphocytes, eosinophils). In this case, the animal, even if clinical symptoms disappear, remains a lifelong carrier of the virus.

With further development of the infection, the virus continues to multiply in the hematopoietic organs and lymphoid system, and also infects glandular epithelial cells throughout the body, including the salivary glands, intestines, esophagus, pancreas, mammary glands, etc.

Symptoms of leukemia

VLK disease manifests itself in the later stages, when the number of leukocytes in the blood is exceeded, and there is no longer a chance of saving the pet. Death occurs due to concomitant diseases that arise due to dysfunction of body systems.

Symptoms may suggest that a cat has a disease, but it does not confirm its presence. To avoid any problems with your pet’s health, you need to show it to the doctor at least twice a year, without neglecting tests.

If you have any of the following symptoms, you should contact your veterinarian and consult with your doctor:

• drowsiness, lethargy, apathy;
• frequent loss of appetite or refusal of favorite foods;
• low activity, lack of interest in games;
• runny eyes and nose, drooling;
• digestive problems;
• frequent colds, cystitis, increased temperature;
• enlarged lymph nodes.

Types and forms of leukemia

An animal can become infected with one or more strains of a retrovirus, which occurs in various forms depending on the animal's immunity.

Depending on the location of the virus and its progressive development, leukemia is noted according to the type of location:

• chest - fluid accumulates in the chest area, causing suffocation;
• abdominal - due to damage to the gastrointestinal tract, upset, jaundice, constipation, dehydration, cachexia appear;
• spinal cord - paralysis of limbs, impaired coordination, unsteady gait;
• kidneys - dehydration, uremia, general poor condition due to intoxication;
• multifocal - affects several organs, enlarged lymph nodes, severe exhaustion, internal bleeding occur.

Blood in a cat's feces
If a pregnant cat has leukemia, her kittens will be stillborn or die within the first days or weeks of life.

VIRAL LEUKEMIA OF CATS

views

Author: Alexandra Fotchenkova Doctor-therapist at the Bely Klyk veterinary clinic

Chronic, or so-called “sluggish” viral infections of cats raise many questions among both animal owners and professional breeders. The disease is often asymptomatic, “carriage” can be hidden - an infected animal, without special examination, can remain “above suspicion” for a long time and come into contact with relatives, exposing them to the risk of infection.

However, such situations are a consequence of insufficient awareness of cat owners, because in practice, identifying and controlling such diseases is a completely feasible task.

In this article we will look at one of the common chronic infections – feline viral leukemia. How to diagnose and control the disease and how to protect cats from infection?

About the VLK virus

Feline viral leukemia (viral leukemia, FLV or FeLV) is a chronic infection that causes serious illness in the body of animals due to disruption of the immune system:

• other infections (bacterial, viral, fungal, parasitic);
• tumors (mainly lymphomas and leukemia);
• diseases of the red bone marrow (anemia, pathology of leukocytes and platelets).

Feline leukemia virus is a retrovirus, it belongs to the same group of viruses as HIV, but it is safe for humans. The virus can awaken and cause illness long after the initial infection. There is no cure yet for this disease, but fortunately, vaccination is available to help prevent lifelong infection and death.

How is VLK transmitted?

Cats can become infected through close contact with infected animals: mutual grooming (licking each other), touching noses when getting to know each other, biting. It is also possible to transmit the infection from mother to kittens through the placenta, during childbirth or breastfeeding, as well as through blood transfusion.

The virus is unstable in the external environment and, despite the fact that sick animals excrete it with all biological fluids (saliva, urine, feces, tears, blood), infection through household items (for example, bowls, trays, furniture) is very unlikely. The virus can be transferred through blood transfusions, so diagnosing FLV is included in the standard list of tests for donor cats.

Only cats suffer from VLK; this infection is not dangerous for other animals and humans.

How does VLK disease progress?

The development of infection in the body can occur in several ways: the cat can overcome the virus, have a temporary infection, or remain infected for life.

With persistent infection, the risks are highest, and the prognosis is pessimistic (80% of cats die within 3 years), however, even after the animal has recovered from VLK, latent infection is sometimes activated by stress, concomitant diseases or decreased immunity during life.

Manifestations of feline viral leukemia

During the onset of the disease, there may be an increase in body temperature, lethargy and enlarged lymph nodes. In some cases, the onset of VLK is asymptomatic. Cats can remain apparently healthy for a long time, and symptoms can be noticed when concomitant diseases develop:

• temperature increase;
• stomatitis;
• secondary infections;
• changes in the lymph nodes and spleen (for example, identified by ultrasound results);
• blood diseases such as anemia (decrease in red blood cells and hemoglobin), leukopenia (decrease in white blood cells), thrombocytopenia (decrease in platelets in the blood);
• diseases of the nervous system (convulsions, impaired coordination of movements);
• tumors and the symptoms of the disease caused by them, which will depend on in which organ the tumor growth occurs. For example, vomiting and/or diarrhea are characteristic symptoms of intestinal lymphoma.

Nonspecific symptoms often appear - lethargy, loss of weight and appetite.

Diagnosis of the disease

VLK is diagnosed by detecting an antigen or nucleic acid in the blood or altered organs (rapid tests, ELISA or PCR). To confirm the diagnosis or determine the course of the infection (permanent or temporary), it may be necessary to check the result using different methods at different intervals.

A diagnosis of persistent infection can be made if the signs of the disease are very characteristic of VLK or several positive results are obtained over a period of 3-4 months. The veterinarian will schedule the test to make a reliable diagnosis.

It is very important to check your pet at least once in its life (regardless of its health status) for FLV carriage; the most correct way is to test the blood in two ways (ELISA/ICA and PCR)

If your cat is diagnosed with VLK, but the general condition of the animal is satisfactory and no abnormalities are found during the examination, the animal can continue to live a normal life, and such a diagnosis in itself cannot serve as a basis for making a decision on euthanasia.

Basic recommendations for the care and treatment of infected cats

If your cat has been diagnosed with viral leukemia, but there are currently no symptoms of the disease, the following measures would be appropriate:

• Exclusively indoor keeping is optimal if such an animal is the only pet in the house and will never leave the apartment. In this case, the cat should be given enough attention, its life should be diversified with the help of games, three-dimensional organization of space and other stimuli.
• Castration/sterilization.
• Feeding only prepared food for cats according to age. Natural, especially raw foods (meat, fish) should be excluded, as they can become a source of infection, for example, helminths.
• The question of vaccinating an infected cat against other infections (rhinotracheitis virus, panleukopenia, calicivirus, rabies) is decided by the doctor depending on the age, health status and risks of infection, which largely depend on the conditions of detention. If you have several cats, the animals have access to the outdoors, or you frequently come into contact with other people's cats, vaccination may be advisable. In this case, it is better to choose a drug containing inactivated antigens, for example, MULTIFEL-4 or FELOVAX vaccines in combination with any anti-rabies component, for example, Nobivac Rabies.
• It is very important to carry out regular antiparasitic treatments: against fleas and ticks (for example, Stronghold, Frontline or Advantage once a month or Bravecto Spot He once every 12 weeks);
• against helminths every 3-4 months (for example, Milbemax, Drontal, Kanikvantel, Prazitsid, Broadline, etc.).
• Some immunomodulators can improve the quality and life expectancy of a cat with VLK, and reduce the likelihood of secondary infections, which are very dangerous for them. For this purpose, recombinant cat interferon is used (Virbagen Omega, used in subcutaneous injections, the drug is not licensed in the Russian Federation).
• Regular preventive examinations by a general practitioner and monitoring of clinical blood tests every 6 months. Biochemical blood test, general urine test, abdominal ultrasound and chest x-ray are recommended once a year. At the discretion of the doctor, additional tests may be prescribed.
• The use of immunosuppressants (drugs that suppress the immune system) should be avoided unless strictly necessary (only if a diagnosis requiring such treatment is confirmed).

If your cat is diagnosed with viral leukemia and there are clinical signs of concomitant diseases, the doctor will prescribe treatment (antibiotics, antiviral or antitumor drugs) depending on the disease. Some current studies of antiviral therapy similar to that used in people with HIV show effectiveness in cats with severe symptoms due to VLK. The drugs Raltegravir and Cat Interferon can be used. The prognosis for the life of such an animal depends on the severity of the disease; Treatment of concomitant diseases is often lengthy and ineffective.

How to protect your cat from viral leukemia

Vaccination against FLV is now available. Vaccination is recommended for cats at risk (all kittens, as well as adult cats walking outside or living with an infected pet, if their isolation from each other is impossible).

Vaccination is carried out from 3 months of age: at the beginning, twice with an interval of 3-4 weeks, then it is repeated every other year. If the risks still persist, then from 1 time per year to 1 time per 3 years, depending on the situation (as decided by the attending physician). Before vaccination, a rapid diagnosis of viral leukemia is carried out.

If you have several animals, it is necessary to conduct a study of all cats in the house twice at an interval of a month. For the health of the infected animal and to prevent infection of other cats, it is recommended to keep them separately. If this is not possible, it is recommended that cats be checked for infection once a year.

It is very important to maintain a comfortable environment for all cats in the house (castration/sterilization, all cats having their own places to rest and play, as well as bowls, drinking bowls and trays; stress prevention (for example, the use of Feliway pheromones).

Share

Diagnostics

If leukemia is suspected, the doctor prescribes a series of tests that should not only detect the presence or absence of the virus, but also determine its strain and form.

1. Blood test - to determine the level of white blood cells in the blood and the erythrocyte sedimentation rate, as well as the presence of anemia.
2. Polymerase chain reaction (PCR) is a study of peripheral blood and its elements that helps identify the pathogen in the body.
3. Immunofluorescence blood test - to detect antibodies to viruses and determine its type.
4. Enzyme immunoassay - detects antibodies and antigens to the virus in the blood.

A PCR test with a positive result shows two colored stripes, one indicates a negative result. After taking blood, you wait 15 minutes and the doctor makes the diagnosis.

If a pet suffers from a malfunction of one organ, he is prescribed an ultrasound or x-ray in order to see tumors or changes in the shape of internal organs. Additionally, a biopsy, gastroscopy, colonoscopy, or laparoscopy may be prescribed.

If the virus is not detected, the disease is not diagnosed, but signs are still present, the doctor prescribes an MRI, which makes it possible to notice the development of the tumor at the initial stage.

The examination must be comprehensive to accurately determine the cause of the disease and make a diagnosis for subsequent treatment.

Treatment

There are no drugs that kill the virus yet. Treatment of leukemia in cats consists of symptomatic care. However, with good care and properly selected therapy, you can maintain high immunity for a very long time, so that your pet will not even feel that he is sick.

For this purpose, immunostimulating drugs (Interferon, Azidotimidine, Raltegravir) are prescribed. High-quality, nutritious nutrition plays an important role. The best choice would be super premium and holistic food. This is the kind of food they use for their pets at the Murkosha shelter.

Read more about the right food: What food to feed your cat

Chemotherapy stops the development of the tumor and, in some cases, reduces its size. Such therapy is carried out with the drugs Cyclophosphamide, Vincristine, etc. Large tumors are removed surgically.

Blood transfusions and antianemic therapy provide good results in treating the disease.

Read about blood transfusions: Blood transfusions in cats

Life expectancy of a cat after infection

The duration and quality of life of an infected cat depends on the conditions under which it is kept.
The incubation period of the virus after infection ranges from 4 days to 8 months. The lifespan of an infected cat depends on its immunity. With sufficient care, she can live from 3 to 10 years, if she does not suffer other diseases and does not show clinical symptoms of the virus. At the same time, she is a carrier and puts other cats at risk.

High mortality occurs in the 3-4th year of the disease, when the symptoms become quite obvious and the disease progresses, causing disruptions in the functioning of the body. This outcome is observed in 90% of cases of infection.

Is the virus transmitted to humans?

For humans, feline leukemia is not dangerous, as it has a completely different nature.

Feline leukemia is not transmitted to dogs or other animals and is only dangerous for cats.

When caring for a sick cat with FLV, it is worth protecting cats from contact with the infected person. It is acceptable to keep a cat with leukemia together with carriers of the same virus or in solitary confinement, subject to quarantine measures.

The virus of this form is not active in the human body and is not transmitted through scratches.

Preventive measures

Diagnosis and subsequent isolation of all cats infected with viral leukemia makes it possible to put a barrier to the spread of the disease within cat communities. To reliably identify sick pets, owners with several cats are recommended to adhere to the following rules:

• Diagnose all pets. If sick individuals are detected, ensure that infected and healthy cats live separately. Do not get new animals for 12 weeks. Regularly disinfect the premises.
• After 3 months, recheck. Separate sick animals; in case of severe disease, euthanize them.
• Conduct regular checks every six months.
• Three month quarantine for all new pets. After this period, incoming cats should be tested before being allowed into contact with other members of the group.

Antibiotics with broad antibacterial effects, vitamin complexes, and microelements are prescribed as symptomatic therapy (treatment). Drugs are used to slow down the growth of tumors. The procedures include chemotherapy and physiotherapy, radiation, and blood transfusions. Such measures allow you to maintain your cat’s health for a considerable time.

The transfer of the pathogen from one individual to another occurs during prolonged contact. The main source of infection is sick animals. In some cases, transmission of the pathogen through blood is possible. Infection most often occurs at an early age. Kittens can get the disease from their mother cat through licking, feeding, or more rarely through the placenta. Animals that have free access to the street and an unlimited number of contacts become infected more often than others. The virus passes from one cat to another through bites, when visiting the tray, or using the feeder. Feline viral leukemia has an incubation period of one to eight months. The disease occurs in a chronic form.

Prevention

It is worth preventing cohabitation or communication with other cats (domestic or street), placing pets in hotels where a previously infectious cat could be located. For the animal’s personal use, use only individual items: tray, drinking bowl, feeder, bed, grooming products. When going on vacation and leaving your pet for foster care, keep in mind that she can easily become infected with leukemia.

A foster cat can easily become infected from other animals.

After the death of a sick cat, it is not recommended to allow other cats into the room where he lived. It is necessary to wait more than two days and thoroughly treat everything with disinfectants, quartz treatment and purchase new bowls, drinking bowls and even food.

Cats living in stressful conditions are most often susceptible to disease and a decrease in their immune resistance to viruses.

Risk group

Cats at risk:

• after surgery or a visit to the clinical table without treatment;
• not vaccinated and not protected from flea bites;
• those exposed to mating with cats that have not been tested for viruses;
• often on the street;
• animals in a shelter or left for foster care;
• a pregnant cat passes the virus to her kittens or through feeding.

If a pet is not at risk, this does not guarantee its complete protection from a dangerous disease. The disease begins asymptomatically, so any of the symptoms listed in this article should be noticed and verified with a special test.

Formation of immunity in cats

Cats that overcome the infection receive non-sterile immunity. The antibody titer sufficient to protect against infection is 1:32.

The decision to administer a vaccine against FLV should be made based on how great the risk of infection is for a given individual.

You should vaccinate:

• Pets that freely leave the house and have contact with other cats.
• Cats living in the same area as sick pets.
• Babies potentially at risk of infection.

Vaccination

Vaccination is the best and most effective way to protect your pet from a terrible and deadly disease. Before the vaccine, it is necessary to carry out a test for carriage of the virus. If it is negative, then vaccinations are given annually from the age of two months. This method of protection helps increase resistance to infection and has a cumulative effect.

Vaccinating a cat against FeLV

The drug is a substance containing living and dead particles of the virus - Purevax.

A timely visit to a doctor for diagnosis of the disease will not protect the cat from a full recovery, but it will prolong its life and prevent the progressive development of the disease.