Content
Cattle hypodermatosis is a chronic disease that is caused by the introduction of subcutaneous botfly larvae into the animal's body. The highest concentration of parasites during infection is observed in the subcutaneous tissue, spinal cord and esophagus; these same areas of the body account for a large share of mechanical damage. In addition, gadfly larvae provoke allergic reactions in cattle, as well as a general depressed state, in which milk yield sharply decreases, the process of fattening young animals slows down, and animal skins depreciate in value.
What is hypodermatosis
In parasitology, cattle hypodermatosis is defined as a seasonal parasitic disease caused in Russia by the larvae of two types of subcutaneous gadflies. The peak of infection generally 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, shortly after leaving the animal's body, 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 compared to adult animals, which greatly facilitates the process of penetration into the subcutaneous tissue for the larvae of the subcutaneous gadfly. The pathogen enters new territories along with infected batches of cattle after the purchase or formation of a new group.
Pathogens
In Russia, hypodermatosis in cattle is caused by the larvae of the common and southern subcutaneous gadfly (or esophagus), photos of which are presented below. The external differences between these two species are minimal; parasites are mainly distinguished by size - the esophagus is slightly smaller than the common gadfly.
The size of the insects is on average 1.5-2 cm. Adults are in many ways similar to bumblebees due to their densely pubescent abdomen.
Sometimes gadflies are often confused with horseflies, however, this is completely wrong. Unlike horseflies, gadflies have underdeveloped oral organs. Moreover, they lack a piercing-sucking apparatus. This means that gadflies cannot cause mechanical damage to cattle through bites, as horseflies and flies do.
The development cycle of hypodermatosis in cattle
The life cycle of the common subcutaneous gadfly and esophagus lasts about a year.The significant difference lies only in the mechanism of penetration into the cow’s body; otherwise, all processes of parasite development are identical:
- To place a clutch of eggs on the skin of cattle, the common gadfly 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 make. The esophagus approaches the herd on the ground, so its appearance goes unnoticed.
- Infection with bovine 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 migrate along them to the esophagus. From there the parasites move into the spinal canal.
- At the late stage of development of bovine 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 subsequently transform into fistulas. The parasites take root inside the seal and remain in the body of the affected individual for some time.
- When the gadfly larva reaches maturity, it leaves the animal’s body 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 it will take for the parasite to develop. Within a few minutes after the gadfly leaves the pupa, it can fly.
The first gathering of subcutaneous gadflies of both species occurs in April in the south of the country. In regions with a cooler climate, the timing of the first gathering shifts closer to summer. Sometimes the gathering continues until the onset of autumn.
The female parasite lays a large number of eggs (from 150 to 500 eggs) on the fur of cattle, but she lays eggs only on cloudless, hot days.In cloudy weather and high air humidity, insect activity is reduced to a minimum. The eggs of subcutaneous gadflies are placed mainly in the area of 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 its eggs, it dies.
Signs and symptoms of subcutaneous gadfly in cows
The first symptoms of hypodermatosis in cattle:
- the appearance of small bleeding wounds on the skin of animals;
- ulcers;
- refusal to eat;
- problems swallowing food;
- swelling of the esophagus;
- dysfunction of the hind limbs up to paralysis;
- uneven gait.
Separately, it is worth noting the presence of hard subcutaneous tubercles on the skin of cattle, which then turn into fistulas - this is the first sign that the individual is infected with the larvae of the subcutaneous gadfly. The total number of tubercles on the body of one animal can reach 100-150 pieces. and more. Most of them are located in the lumbar region of cattle.
When opened, large accumulations of hardened connective tissue capsules can be found in the muscle and subcutaneous layer - these are traces of the migration of larvae throughout the animal’s body. An autopsy also shows severe tissue swelling and damage to blood vessels, along which living larvae can be found. A large number of capsules with parasites are located in the esophagus of cattle.
Diagnosis of hypodermatosis in cattle
Hypodermatosis in cattle is practically asymptomatic at the first stage of larval development; clinical manifestations are typical only for heavy infestation of an individual by parasites. To detect botfly larvae in cattle at an early stage of hypodermatosis, it is necessary to conduct serological studies.You can also do an allergic reaction test, especially if the farm is located in a region unfavorable for hypodermatosis.
In the fall, blood is collected from cattle - during this time period the concentration of antibodies in the collected material reaches its highest point. Using indirect hemagglutination in the laboratory, it is possible to detect the presence of parasites in livestock at the very beginning of the development of hypodermatosis.
A test for an allergic reaction is prepared on the basis of biological material from gadfly larvae. The resulting material is injected subcutaneously into cattle. If a characteristic thickening appears on an area of skin 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 oblong lumps begin to cover the animals’ backs. After 1-2 months they turn into large nodules. Upon closer inspection, you will find tiny holes in them.
It is important to remember that some 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 subcutaneous gadfly in cattle
In order to get rid of subcutaneous gadfly larvae in cattle, you can resort to the help of chemicals or remove the parasites mechanically. The most effective means include:
- «Hypodermin-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. Repeated treatments are not required.
- «Hyphlovos" Directions for use: 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.
- «Fascoverm" Dosage - 1 ml per 20 kg of weight of an individual with hypodermatosis (but not more than 10 ml per animal). The drug is administered subcutaneously once.
- «Ivomek" The product is for subcutaneous single use, the recommended dosage is 0.2 mg per 1 kg of weight. The drug cannot be used to treat hypodermatosis in pregnant cows that are about a month away from calving.
- «Cydectin" Injected subcutaneously once at the rate of 0.5 ml for every 25 kg of 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 adult subcutaneous gadflies gradually decreases. If the disease has been advanced, in the later stages treatment of hypodermatosis includes surgery - it is recommended to remove the fistula tracts along with dead tissue. In addition, it is necessary to clean the wounds from pus. In order to stimulate healing, the connective tissue of the sick individual is additionally excised, and at the same time compensatory therapy is introduced.
The larvae of the subcutaneous gadfly are removed mechanically only at the late stage of hypodermatosis. By this time, the openings of the fistula on the skin have reached quite large sizes - 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. Under no circumstances should you throw botfly larvae onto 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, procedures for mechanical removal of parasites from cattle are carried out in several stages. The optimal frequency of manual treatment for hypodermatosis is 8-10 days.
Prevention of hypodermatosis in cattle
In order to minimize the likelihood of cattle contracting hypodermatosis, it is necessary to observe at least the most basic preventive measures. This way, you won’t have to fight a long and grueling fight against parasites. The full range of preventive measures includes the following recommendations:
- Cattle are periodically examined for the presence of fistulas. Particular attention should be paid to the back and lower back areas - from the end of March to May, these areas must be palpated from time to time. The presence of subcutaneous nodules is one of the most obvious signs of the disease; even non-professionals can detect them. The further course of treatment for hypodermatosis in cattle is determined by the veterinarian.
- At the end of August - beginning of September, it is recommended to treat cattle with special anti-parasite preparations that destroy botfly larvae at an early stage of development. Treatment of cattle against hypodermatosis should apply to the entire herd, and not just to individuals suspected of having the 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 is suspected of having hypodermatosis, it is not allowed to graze. Thus, the larvae of gadflies will not be able to move to the pasture and infect the rest of the herd.
- The likelihood of developing hypodermatosis in cattle can be reduced by staggering grazing times. During the grazing period, it is better to let cows and horses graze early in the morning, before 10:00, or late in the evening, after 18:00. During the day, it is better to keep animals indoors or under a canopy. This organization of grazing takes into account the activity of gadflies during the day - the insects gather at the peak of the heat. In conditions of low temperatures, dampness and wind, gadflies show virtually no activity.
To prevent 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:
Conclusion
Hypodermatosis in cattle is easier to prevent than to treat, since diagnosing sick animals in the early stages is difficult due to the hidden nature of the disease. Timely treatment of animal skins with medications helps reduce the risk of cattle infection by 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 frequent cases of gadfly larvae passing on to humans. In addition, parasites can invade the body of domestic animals, such as dogs.
