Hypodermatosis in cattle is a chronic disease that is caused by the introduction of the larvae of subcutaneous gadflies into the animal's body. The highest concentration of parasites during infection is observed in the subcutaneous tissue, spinal cord and esophagus, and a large proportion of mechanical damage falls on these parts of the body. In addition, gadfly larvae provoke allergic reactions in cattle, as well as a general depression, in which milk yield sharply decreases, the process of feeding young animals slows down and animal skins are devalued.
What is hypodermatosis
In parasitology, cattle hypodermatosis is defined as a seasonal parasitic disease caused on the territory of Russia by the larvae of two species of subcutaneous gadflies. The peak of infection mainly occurs in late spring and early summer - it is at this time that the subcutaneous pupae are destroyed from the inside by fully formed adults, which, soon after leaving the body of the animals, are ready to lay a new batch of eggs.
Most often, an outbreak of hypodermatosis in cattle begins with infection of young animals, since they have thinner skin in comparison with adult animals, which greatly facilitates the process of penetration into the subcutaneous tissue for the larvae of the subcutaneous gadfly. The causative agent of the disease penetrates into new territories together with infected lots of cattle after purchasing or forming a new group.
Important! The greatest difficulty in the prevention and treatment of hypodermatosis in cattle is the latent nature of the disease - in most cases it is very difficult for a layman to identify the symptoms of the disease.
Causative agents of the disease
In Russia, hypodermatosis in cattle is caused by the larvae of the common and southern subcutaneous gadfly (or esophagus), the photos of which are presented below. External differences between these two species are minimal, mainly the parasites are distinguished by size - the esophagus is slightly smaller than an ordinary gadfly.
The size of insects is on average 1.5-2 cm. Adults are in many ways similar to bumblebees due to the densely pubescent abdomen.
Sometimes gadflies are often confused with horseflies, however, this is fundamentally wrong. Unlike horseflies, gadflies have underdeveloped mouth organs. Moreover, they do not have a piercing-sucking apparatus. This means that gadflies cannot cause mechanical damage to cattle through bites, as gadflies and flies do.
Important! In the course of their vital activity, gadfly larvae secrete hypodermotoxin into the body of sick animals - an extremely toxic substance that can enter the human body together with milk or cattle meat products.
The cycle of development of hypodermatosis in cattle
The life cycle of an ordinary subcutaneous gadfly and esophagus lasts about a year. A significant difference lies only in the mechanism of penetration into the body of the cow, otherwise all the processes of development of parasites are identical:
- The common gadfly for placing a clutch of eggs on the skin of cattle moves from individual to individual in flight, which plunges the herd into panic - the animals are frightened by the loud crackling sound that the insect's wings emit. The esophagus approaches the herd along the ground, so its appearance remains unnoticed.
- Infection with cattle hypodermatosis occurs according to the following scheme: larvae hatched from eggs crawl along the hair onto the skin, penetrate inside and along the blood vessels or along them migrate to the esophagus. From there, the parasites travel to the spinal canal.
- At a late stage in the development of cattle hypodermatosis, the larvae are located in the subcutaneous layer, where they molt several times. The consequence of molting is the formation of dense capsules, which are subsequently transformed into fistulas. The parasites take root inside the seal and remain in the body of the affected individual for some time.
- Having reached maturity, the gadfly larva leaves the body of the animal and falls to the ground or into manure. There she pupates and after 1.5-2 months turns into a full-fledged individual. The cooler the climate in a given area, the longer the parasite will develop. Within a few minutes after the gadfly leaves the chrysalis, he can fly.
The first gathering of hypodermic gadflies of both species takes place in April in the south of the country. In regions with a cooler climate, the dates of the first rally are shifted closer to summer. Sometimes the gathering continues until the onset of autumn.
The female of the parasite lays a large number of eggs on the cattle wool (from 150 to 500 eggs), but she only clutches on cloudless hot days. In cloudy weather and high humidity, insect activity is minimized. Subcutaneous gadfly eggs are placed mainly in the udder, abdomen, and also on the sides of cattle.
The subcutaneous gadfly does not live long, only a few days. After the insect lays eggs, it dies.
Signs and symptoms of a subcutaneous gadfly in cows
The first symptoms of hypodermatosis in cattle:
- the appearance of small bleeding wounds on the skin of animals;
- refusal to eat;
- problems swallowing food;
- swelling of the esophagus;
- disruption of the hind limbs up to paralysis;
- uneven gait.
Separately, it is worth noting the presence in cattle of hard subcutaneous tubercles on the skin, which then turn into fistulas - this is the first sign that an individual is infected with the larvae of a subcutaneous gadfly. The total number of tubercles on the body of one animal can reach 100-150 pcs. and more. Most of them are located in the lumbar region of the cattle.
When opened, large accumulations of hardened capsules from connective tissues can be found in the muscle and subcutaneous layer - these are traces of the migration of larvae along the body of the animal. An autopsy also reveals severe tissue edema and damage to blood vessels, along which live larvae can be found. A large number of capsules with parasites are found in the cattle esophagus.
Diagnostics of the cattle hypodermatosis
Hypodermatosis in cattle is almost asymptomatic at the first stage of larval development; clinical manifestations are typical only for abundant parasite infestation of an individual. To detect gadfly larvae in cattle at an early stage of hypodermatosis, it is necessary to conduct serological studies. You can also do an analysis for an allergic reaction, especially if the farm is located in a region that is unfavorable for hypodermatosis.
In autumn, blood is collected from cattle - during this time period, the concentration of antibodies in the collected material reaches its highest point. With the help of indirect hemagglutination in the laboratory, it is possible to identify the presence of parasites in the livestock at the very beginning of the development of hypodermatosis.
Important! The most unfavorable time for serological testing of cattle is in the spring - early summer. The efficiency indicator reaches its minimum with the onset of June.
A test for an allergic reaction is prepared on the basis of biological material from gadfly larvae. The resulting material is injected into cattle subcutaneously. If a characteristic thickening appears on the skin area within 5-6 hours, the reaction to the test is positive.
It is possible to independently detect progressive hypodermatosis in cattle only with the onset of winter. In the south of the country, the disease manifests itself already in December, in the north - in February, when elongated seals begin to cover the back of the animals. After 1-2 months, they turn into large nodules. Closer inspection reveals tiny holes.
It is important to remember that some of the symptoms of hypodermatosis coincide with the clinical picture of other diseases. In this regard, for a more accurate diagnosis, it is necessary to be guided by the principles of differential diagnosis of hypodermatosis in cattle.
Treatment of a subcutaneous gadfly in cattle
In order to get rid of the larvae of the subcutaneous gadfly in cattle, you can resort to using chemicals or remove parasites by mechanical means. The most effective remedies include:
- "Hypodermine-chlorophos". This drug against hypodermatosis in cattle is best suited for isolated cases of infection. The drug is applied externally to the lumbar region and spinal column in a volume of 8 ml per 100 kg of animal weight. No reprocessing is required.
- "Hypkhlofos". Method of application - local treatment in a volume of 15-18 ml per individual. A month after the procedure, it is necessary to apply the drug to the animal's skin again.
- Faskoverm. Dosage - 1 ml per 20 kg of body weight of a patient with hypodermatosis (but not more than 10 ml per animal). The drug is administered subcutaneously once.
- Ivomek. Means for subcutaneous single use, the recommended dosage is 0.2 mg per 1 kg of body weight. The drug should not be used to treat hypodermatosis in pregnant cows that have about a month before calving.
- "Cidectin". Injected subcutaneously once at the rate of 0.5 ml for every 25 kg of body weight. Unlike the previous remedy, "Cydectin" is approved for use throughout pregnancy.
Treatment of livestock against hypodermatosis is carried out in the fall, when the activity of adults of the subcutaneous gadfly gradually decreases. If the disease has been started, in the later stages, the treatment of hypodermatosis includes surgical intervention - it is recommended to remove the fistulous passages along with the dead tissues. In addition, it is necessary to cleanse the wounds of pus. In order to stimulate healing, the connective tissue of the sick individual is additionally excised, at the same time, compensatory therapy is introduced.
Mechanically, the larvae of the subcutaneous gadfly are removed only at a late stage of hypodermatosis. By this time, the holes of the fistula on the skin have reached a sufficiently large size - up to 5 mm, which allows the larva to be squeezed out of the seal on the skin. All extracted parasites must be collected in one container, after which they are burned. In no case should you throw gadfly larvae on the ground. Parasites can burrow into the ground, pupate and eventually turn into a full-fledged individual.
Since the larvae of the subcutaneous gadfly reach maturity at different times, the procedures for the mechanical removal of parasites from cattle are carried out in several stages. The optimal frequency of manual processing for hypodermatosis is 8-10 days.
Important! After all procedures, the livestock of cattle is examined again. There should be no bumps, seals or fistulas on animal skins.
Prevention of hypodermatosis in cattle
In order to minimize the likelihood of cattle with hypodermatosis, at least the most basic preventive measures must be followed. So, you don't have to wage a long and exhausting struggle with parasites. A full range of preventive measures includes the following recommendations:
- Cattle are periodically examined for fistulas. Particular attention should be paid to the area of the back and lower back - from the end of March to May, these areas need to be felt from time to time. The presence of subcutaneous nodules is one of the most obvious signs of the disease, and even non-professionals can detect them. The further course of treatment of hypodermatosis in cattle is determined by the veterinarian.
- In late August - early September, it is recommended to treat cattle with special preparations against parasites that destroy gadfly larvae at an early stage of development. Treatment of cattle against hypodermatosis should be extended to all livestock, and not just to individuals with suspected disease. It is advisable to complete all procedures before transferring cattle to summer housing.
- The spread of parasites is limited by the isolation of sick individuals. If an animal has a suspicion of hypodermatosis, it is not allowed to graze. So, gadfly larvae will not be able to move to pasture and infect the rest of the herd.
- The likelihood of developing hypodermatosis in cattle can be reduced by shifting the grazing time. During the grazing period, cows and horses are best allowed to graze early in the morning, before 10:00, or late in the evening, after 18:00. During the day, animals are best kept indoors or under a canopy. Such an organization of grazing takes into account the activity of gadflies during the day - the gathering of insects occurs at the peak of the heat. In conditions of low temperatures, dampness and wind, gadflies practically do not show activity.
For the prevention of hypodermatosis in cattle, primarily pyrethroids and chlorophos are used. The recommended processing frequency is 20-30 days.
You can learn more about the treatment and prevention of hypodermatosis in cattle from the video below:
Important! The drug "Aversect", which is administered by intradermal injection, has proven itself well in the fight against parasites. It scares off adult gadflies and destroys insect larvae at an early stage of development.
Hypodermatosis in cattle is easier to prevent than to cure, since the diagnosis of sick animals in the early stages is complicated by the latent nature of the course of the disease. Timely treatment of animal skins with drugs helps to reduce the risk of infection of cattle with gadflies to a minimum.
All manipulations with sick individuals with hypodermatosis are recommended to be carried out with protected skin and eyes. Close contact with cattle during this period can lead to infection - there are often cases when gadfly larvae passed to humans. In addition, parasites can invade pets such as dogs.