Infectious anemia of horses affects one-hoofed animals, including agricultural ones. It is called INAN by a slow virus of the Retroviridae family and is characterized primarily by damage to the blood-forming organs. Horses, donkeys and mules can be sick in farms with infectious anemia.
A bit of history
This disease was first described in France in 1843 by Lignay. The contagious nature of infectious anemia was proved somewhat later - in 1859 by Anginnard, who introduced as an experiment blood from infected animals to healthy ones. In 1904, scientists Carre and Bale established that the disease is caused by a virus. In 1969, the latter was isolated by Kono researcher in the culture of white blood cells.
In Russia, the first cases of INAN horse disease were detected in 1910. Methods for diagnosing this disease in our country were developed in 1932 by Ya. E. Kolyakov et al. This disease was especially widespread on farms during the First and Second World War. At the moment, horse breeders are faced with such a problem not only in Russia, but also in Japan, India, Australia, and the USA. Inan is also found on farms on the African continent and in Europe.
Features of the disease
The nature of the INAN may be acute, subacute or chronic. Infectious anemia often affects horses. Donkeys and mules are more resistant to the Retroviridae virus. Man and not one-hoofed animals cannot become infected with infectious anemia.
A characteristic feature of this disease is the alternation of seizures and remissions. At the same time, each new exacerbation proceeds in a more severe form, which indicates an allergic feature of the horse's INAN.
The epidemic of infectious anemia on farms usually lasts 3-5 months. First, horses with an acute course of the disease are identified on the farm. In the future, many animals are diagnosed with chronic and latent forms.
Retroviridae virus strains isolated in different parts of the globe are antigenically identical. A feature of Retroviridae, among other things, is its resistance to chemical factors. At temperatures from 0 to 2 ° C, the INAN virus is able to persist for up to 3 years. Under normal conditions, he usually lives in urine and slurry for up to 2.5 months, and in feed for 9 months.
Infection pathways
Outbreaks of this disease are often observed in farms where sanitary standards are not respected. The Retroviridae virus is isolated in sick horses mainly with secrets and excrements containing protein: urine, feces, milk, nasal mucus. Therefore, INAN can be transmitted including through infected litter, hay, water, manure, feed and other infected objects.
However, most often this bloodsucking insect carries this disease of horses. In the saliva of horseflies, mosquitoes and ghost flies, the Retroviridae virus can persist for a very long time. For infection, it is enough that at least 0.1 ml of infected blood penetrates into the body through the skin of the animal. Therefore, the disease in one-hoofed animals can begin to develop already from one bite.
Due to the fact that the virus of infectious anemia of horses is usually transmitted through insects, outbreaks of this disease most often occur in the warm season. At the same time, horses, donkeys and mules found on farms located next to ponds and marshes are most susceptible to it. In winter and spring, outbreaks of this disease occur, but most often they are only exacerbations of the chronic or latent course of the disease.
Features of infection
After penetration into animals, the Retroviridae virus spreads to all organs and tissues. It reproduces especially intensively in the bone marrow and in the blood. Its negative effect is manifested primarily in the fact that it is able to inhibit hemolysis and erythropoiesis of red blood cells. 5 days after infection, the amount of the latter in the blood of a monocotyledon decreases to 1.5 ... 3 million per 1 μl. As a result, hemotocrit and hemoglobin levels are reduced by about 50%. After 24 hours, the ESR in the animal in the blood increases significantly.
Does sustainability develop
Immunity in this disease in horses, donkeys and mules is non-sterile. According to the results of studies, virus-neutralizing precipitating antibodies are present in the blood of infected animals. Having experienced INAN, one-holed ones in many cases acquire some resistance to this ailment. However, the relationship between the strength of the immunity of horses to the Retroviridae virus and humoral antibodies has been clarified at the moment, unfortunately, is not enough. Accordingly, the serum for vaccinations from INAN was not developed.
Incubation period
After infection in animals, the latent development of the disease begins. Within 5-90 days (usually 10-30 days), the virus actively multiplies in the organism of the one-hoofed, but does not manifest itself in any way with external signs. It is impossible to determine the presence of disease in one-hoofed animals at this time.
Such a long incubation period of the INAN is explained by the fact that the body at this time manages to restore the affected cells. However, after a high number of Retroviridae units accumulate in the body, the ailment becomes active.
Features of the acute course
With this development, infectious anemia in horses, donkeys and mules is accompanied by fever, sweating, and inoperability. The body temperature of animals rises to 42 ° C. The acute form of INAN develops in 15-16% of infected horses.
On the conjunctiva and mucous membranes in the unexperienced with this course of the disease, point hemorrhages are observed. The pulse in animals is weak arrhythmic. Horses, donkeys and mules die 7-30 days after infection. In surviving animals, the disease becomes chronic and a period of remission sets in.
Occasionally, an oversharp course of this disease can be observed in one-hoofed animals. In this case, the animal may die within a few hours or 2-3 days after infection. In the period of remission of clinical signs of the disease, in one-hoofed animals is not observed.
Symptoms of acute and super acute form
Determining INAN in horses, mules, and donkeys is usually not very simple. This is especially true for super-acute and acute forms of the disease. Signs of INAN in this case are masked by the symptoms of many other ailments. With a super-acute form, the animal will observe:
- fever;
- general depression;
- rapid breathing;
- palpitations;
- vomiting
- hind limb paralysis;
- bloody diarrhea.
The acute form of the disease in the unexperienced is accompanied by the same, but somewhat less pronounced and sharp symptoms, as the super-acute. In addition, in this case, animals can observe:
- swelling in the limbs, chest and abdomen;
- a sharp decrease in body weight;
- nosebleeds.
How does INAN flow in chronic form?
After a period of remission in sick animals, new attacks occur with almost the same symptoms as in the acute course. During exacerbations, some animals may also die. The chronic form differs from the acute, among other things, the type of pathological changes. In both of these cases, animals have hemorrhagic diathesis and granular-fatty degeneration of parenchymal organs. But in the victims of exacerbation in the chronic form of one-hoofed animals, the liver also acquires a “muscat” appearance. That is, in the context it resembles nutmeg (on a general yellowish or red background, dark red spots are noticeable).
Very often, chronic infectious anemia in one-hoofed animals is a continuation of the acute course of the disease. However, sometimes it can arise as an independent form.
Symptoms of a chronic form
During the period of remission INAN in horses practically does not manifest itself in any way. During seizures, animals may experience the following symptoms:
- fever and shortness of breath;
- palpitations;
- muscle tremors;
- persistent sweating;
- decreased performance.
The temperature in the horse during exacerbations rises to 42 ° C.
Subacute form
The chronic course of the disease in one-hoofed animals is often preceded by a subacute. This period can last for 1-2 months. The main symptom of the subacute form is increased fever. The horse’s body temperature “jumps” at this time. Periods of remission and exacerbations in such a course succeed each other very quickly. At the end of the subacute period, the condition of the animals improves dramatically, but after 3-15 days the disease returns. After several cycles of remissions and exacerbations, animals develop weakness and exhaustion. One-hoofed can also die with this form of the disease.
Latent current
With this form of the disease, animals only occasionally experience slight temperature increases. Also, the latent development of the disease is characterized by mild morphological changes. A horse with this form of ailment remains functional. But in any case, animals with a latent course of infectious anemia are virus carriers. That is, upon contact with healthy healthy hoofed animals, infection can easily occur. The same goes for insect bites.
Treatment
Infectious anemia can cause truly irreparable harm to the household. The fact is that the treatment of this disease has not been developed. Specialized medicines designed to combat INAN simply do not exist. All infected animals are slaughtered. Such a measure is taken to prevent the spread of infection to healthy horses, donkeys and mules.
Security measures
Horse breeding in Russia is quite well developed. Therefore, the Retroviridae virus can easily and quickly migrate between farms. Accordingly, if INAN is detected on the farm, it is declared dysfunctional in the prescribed manner and restrictions are imposed.
In the case of diagnosing equine infectious anemia on the farm, it is prohibited to:
- withdrawal from the farm of animals and introduction of new ones into it;
- rearrangement of susceptible animals;
- the implementation of serum preparations obtained from animals without prior disinfection.
All livestock on the farm are inspected, and laboratory blood tests of one-holed animals are also carried out. Clinically sick animals are slaughtered, and meat is disposed of from them. Those hoofed animals whose diagnosis is doubtful are also killed. Their meat is subjected to laboratory research. If it is deemed suitable, it is additionally neutralized by welding. In the future, the meat of one-hoofed animals is fed by carnivorous farm animals or poultry. It is not intended to add this product to pigs only. After slaughter, the head, bones and organs of diseased animals are disposed of, and the skins are disinfected and sent to tanneries.
One-holed, recognized healthy, again checked after a month. After 30 days, another check is done. If both times sick animals are not detected, the economy is considered safe according to INAN. Quarantine on the horse farm is stopped 3 months after the death or slaughter of the last sick animal. From this moment, certain restrictions are removed from the farm. However, the sale of animals from such a farm is possible only 3 months after the removal of quarantine, provided that a study of blood serum by RDP with a negative result is carried out.
How to conduct an inspection
This procedure must be performed by a veterinarian. The main task of the specialist during the examination is to identify:
- duration of symptoms;
- the nature of the symptoms;
- disease dynamics;
- identification of sources of infection and causes of the disease.
At this point, the veterinarian determines the nature of the fever. He also listens to the heart of the animal in order to detect interruptions in his work. In addition, a specialist in paralysis of the limbs of an animal identifies the causes of a disorder of nervous activity.
How are laboratory tests carried out?
Horse breeding in Russia has been developing for several centuries. And of course, over this long period, effective methods have been developed for diagnosing a wide variety of diseases of the one-hoofed. In the XX century. Experts have also developed laboratory methods to detect infectious diseases of such animals with high accuracy.
To diagnose infectious anemia in horses, mules and donkeys, specialists are currently testing blood for pathologies. In this case, serological tests are carried out in the laboratory. Also, the blood of animals with suspected INAN is subjected to microbiological studies based on the RDP protocol. This technique allows you to identify Retroviridae at any stage of its development.
When conducting studies to diagnose INAN, blood is determined, among other things:
- the number of red blood cells, white blood cells and hemoglobin;
- ESR;
- white blood cell count;
- retraction of a blood clot.
Important
It is believed that laboratory blood tests for infectious anemia are mandatory. As already mentioned, the symptoms of this disease are not too pronounced and may be similar to the signs of many other diseases.
During a routine examination, equine infectious anemia, for example, can be confused with:
- leptospirosis;
- rhinopneumonia;
- nuttalliosis;
- trypanosomiasis;
- pyroplasmosis.
Pathological signs
After opening the carcasses of slaughtered or dead animals with infectious anemia, the following are observed:
- exhaustion, pallor and yellowness of the mucous membranes;
- the presence of small hemorrhages on the serous integument of the intestine and heart;
- the accumulation of histiocides, macrophages and lymphoid cells in the liver;
- strong infiltration of spleen tissue by immature red blood cells;
- lymph node swelling and enlarged spleen.
Such changes are not observed only in animals with a latent form of the disease.
The heart in infected one-hoofed animals is usually enlarged, and the myocardium has a gray-clay color. The spleen in such animals is in many cases filled with blood, and the liver is enlarged and has a flabby structure. The subcutaneous and axillary tissue of the fallen horses is icteric and is riddled with hemorrhages.
How is disinfection performed?
In addition to the slaughter of infected animals, in dysfunctional farms, of course, all measures are taken to prevent the spread of infection. After slaughter of sick individuals, the following is produced:
- the stables themselves;
- territories around them;
- care items and tools;
- waste.
Sodium hydroxide is most often used for disinfection. Sometimes, a 2% formaldehyde solution or 4% sodium hydroxide solution is also used for this purpose. All of these substances can kill the virus of infectious anemia almost instantly.
In the quarantine period, in a dysfunctional farm, processing is supposed to be done once every 2 weeks. When breeding horses in stables on farms, of course, a lot of manure accumulates. After the slaughter of sick animals, it is neutralized biothermally on the farm for 3 months.
Disease prevention
Thus, it is impossible to cure infectious anemia in horses, donkeys, mules. Therefore, in order not to incur losses, farm owners must take measures to prevent the development of this disease in one-hoofed animals.
Firstly, on farms, strict sanitary and veterinary control over the condition of animals must be observed. In order to avoid cattle death due to INAN and the need to slaughter part of the livestock, the following preventive measures are proposed:
Compliance with the rules of moving and replenishing the herd. All new animals entering the farm must first be quarantined in separate rooms.
Avoiding contact of horses, mules, and donkeys with infected animals.
Use during medical procedures and examinations only clean, disinfected equipment.
Periodic treatment of horses, donkeys and mules with insecticides. Such a measure is necessary to prevent horse bites in the herd or at the stable by horseflies, flies, etc. The treatment of one-hoofed animals in insect farms is usually carried out with a 3% solution of creolin.
Farm workers must wear protective clothing while performing their duties. This measure is necessary in order to prevent the transfer of infection from personal households.