Horses, donkeys, mules and other animals belonging to the order of equids are susceptible to severe infectious diseases. Glanders is a disease caused by gram-negative bacteria and transmitted from infected animals to healthy animals and people. The risk of death after diagnosing glanders in horses is high. Today, the disease is most often recorded in Asian countries.
Description of the disease and its historical background
The infection was described in detail in the second half of the 19th century. Leffler isolated a pathogenic bacterium from the contents of skin formations on the animal's rump.A few years later, Russian veterinarians created a method for diagnosing glanders in horses, which made it possible to begin the fight against glanders. Veterinarians have developed a test for the administration of mallein. This method remains the most informative to this day.
An outbreak of the disease in Russia was observed from 1917 to 1924. The horse at this time was a valuable working unit: it was in demand in the fields, and was also used for movement between populated areas. In addition, there was a separate category of army horses, which soldiers could not do without.
The government has developed a special action plan to prevent and diagnose glanders. During this period, more than 100 thousand animals were destroyed. The complete elimination of glanders in Russia was achieved by 1940.
The causative agent of the disease
The infection is caused by the bacterium Burkholderia mallei, which belongs to the second group of pathogenicity. The microorganism causes massive damage to horses, so it was used as a biological weapon during the 1861 War in America. This pathogen is capable of infecting horses and humans in a short time.
The pathogen is a short rod, arranged in the form of bacilli, connected in pairs. They do not have spores or capsules. During the period of existence they remain absolutely motionless, but begin to grow when they enter a nutrient medium.
Physico-chemical properties of pathogens:
- exist at temperatures from -10 to +55 °;
- resistant to some antibiotics;
- do not withstand prolonged treatment with disinfectants.
When a bacterium enters a nutrient medium, it begins to grow. A dense, brown-brown coating forms on the infected surface.If the pathogen enters water or soil, its properties can persist for 2 months. Inside the animal's corpse, in its excrement, the bacterium exists for 2 to 3 weeks.
Reference! The bacterium dies under the influence of UV radiation and cannot withstand heating to temperatures above +80 °.
Symptoms and course of glanders in horses
Epizootology, or mass spread, begins with contact with an infected animal. Sick horses excrete the pathogen in secretions from their nostrils. It is also found in saliva and the contents of skin formations throughout the surface of the croup. This means that a healthy horse can become infected through contact with a sick horse through the skin. If the pathogen comes into contact with a microtrauma on the croup of a healthy horse, then infection occurs much faster than when entering through the sinuses and respiratory tract.
Individuals with chronic glanders are especially dangerous. In the absence of visible signs of illness, they spread the pathogen around themselves by dispersing salivary or nasal secretions. Such horses can infect a healthy horse with short contact and cause epizootology.
In addition, transmission occurs during the exchange of horse equipment, during the intake of feed or through manure.
A factor that provokes infection is keeping animals in cramped stable stalls. But during pasture grazing, the transmission of the pathogen slows down significantly. This is due to the high resistance of horses to glanders during grazing and the low ability of the pathogen to spread under the influence of direct sunlight.
After infection, the incubation period begins. It lasts from 3 days to 2 weeks. Then the symptoms appear, and they determine the type of course of the disease:
- Acute course.It is characterized by a significant increase in body temperature (up to 40-41 °), hyperemia of the mucous membranes. The horse begins to breathe intermittently, becomes weak and lethargic. On the second day, nodules with a red rim appear on the mucous membrane of the nostrils; they quickly merge, forming a continuous stripe. The rash begins to undergo necrosis, and ulcers with purulent contents form. At the same time, skin lesions develop on the inner thigh and neck area. The last symptom is elephantiasis or significant enlargement of the limbs.
- Chronic course. With a chronic disease, the horse’s body temperature periodically rises and coughs. Animals lose weight. Wounds begin to appear on the mucous membrane of the nostrils, which then heal. Chronic glanders can last for several months or several years. It is detected during a thorough examination, but is almost not diagnosed during a superficial examination without collecting biological material and clinical examination.
- Latent flow. This is a lifelong type of disease that can become acute as the horse’s living conditions worsen. Latent glanders is almost impossible to diagnose without detecting signs of an acute course.
Diagnostic methods
Among the methods for detecting glanders, the most informative is the allergic method. It includes 2 types of biological material collection:
- Ophthalmological test. Mallein is placed into the conjunctival sac and the reaction is observed. After 2-3 hours, if the reaction is positive, lacrimation and discharge of pus begin. If the diagnosis is negative, then slight redness of the eye occurs.
- Subcutaneous test.It is carried out if the horse is diagnosed with eye diseases. A maleic injection is injected under the skin. After 6-8 hours the reaction is read. If swelling appears at the injection site and body temperature rises (up to 39-40°), then the test is considered positive. A negative reaction assumes the absence of swelling and fever.
In case of positive samples, bacteriological studies are carried out. The diagnosis is made subject to the presence of three components:
- detection of changes in internal organs that are characteristic of glanders;
- isolation of a pathogen from biological material;
- presence of external signs of glanders.
Treatment
Horses suspected of having glanders are kept in quarantine. Until diagnosis is made, animals are administered antibiotics of the penicillin or streptomycin group. At the same time, injections are given with vitamins and compounds to improve blood quality.
Attention! To prevent infection, horses with a confirmed diagnosis are taken to slaughter. Animal corpses are burned without autopsy.
Prevention and elimination
Horses that meet sanitary veterinary standards are allowed to be imported into the country. After import, the horses are quarantined where they undergo various diagnostic checks and are also tested for the presence of glanders. To prevent infections, measures have been introduced to comply with a mandatory preventive plan horse vaccinations.
If the maleic test gives a positive result, then the measures pre-established by the protocol are carried out to destroy the individual and treat the premises:
- the corpse is burned completely away from residential premises or agricultural facilities;
- Bedding, manure and remaining feed are burned along with the corpse;
- the soil after burning is treated with formaldehyde or bleach solution;
- the walls of the premises in which the horse was kept are treated with a 20% bleach solution;
- After disinfection, the walls are whitened with slaked lime.
The clothes and shoes of personnel who worked with infected horses are treated separately. Protective suits are boiled for 15-20 minutes in a 2% soda solution. Gloves, hats, and aprons are left in the chloramine solution for 20 minutes.
Boots and galoshes are treated with a chloramine solution. Personal clothing is kept in a steam-formalin chamber for 10-15 minutes. Transport that was located near the source of infection is additionally treated with a 1 or 3 percent chloramine solution.
