Hypodermatosis CRS

Hypodermatosis of cattle is a chronic disease that is caused by the introduction of larvae of subcutaneous gadflies into the body of an animal. The highest concentration of parasites during infection is observed in the subcutaneous tissue, spinal cord and esophagus, the same areas of the body account for a large proportion of mechanical damage. In addition, gadfly larvae provoke allergic reactions in cattle, as well as a general depression, in which milk yields drop sharply, the process of fattening young animals slows down, and animal skins depreciate.

What is hypodermatosis

In parasitology, cattle hypodermatosis is defined as a seasonal parasitic disease caused in Our Country by the larvae of two species of subcutaneous gadflies. The peak of infection mainly occurs at the end of spring and the beginning of summer – it is at this time that subcutaneous pupae are destroyed from the inside by fully formed adults, which are ready to lay a new batch of eggs shortly after leaving the body of animals.

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 causative agent of the disease enters new territories together with infected batches of cattle after purchase or formation of a new group.

Causative agents of the disease

In Our Country, hypodermatosis in cattle is caused by larvae of the common and southern subcutaneous gadfly (or esophagus), photos of which are presented below. External differences between these two species are minimal, mostly parasites are distinguished by size – the esophagus is slightly smaller than an ordinary gadfly.

The size of insects averages 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 lack a piercing-sucking apparatus. This means that gadflies cannot cause mechanical damage to cattle through bites, as horseflies and flies do.

The cycle of development of hypodermatosis in cattle

The life cycle of an ordinary subcutaneous gadfly and esophagus lasts about a year. The essential difference lies only in the mechanism of penetration into the body of a cow, otherwise all the processes of development of parasites are identical:

1. The common gadfly for laying 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 wings of the insect make. The esophagus approaches the herd on the ground, so its appearance goes unnoticed.
2. Infection with cattle hypodermatosis occurs according to the following scheme: the larvae hatched from the eggs crawl along the hair to the skin, penetrate inside and migrate through the blood vessels or along them into the esophagus. From there, the parasites move into the spinal canal.
3. At the late stage of 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 converted into fistulas. Parasites take root inside the seal and remain in the body of the affected individual for some time.
4. Having reached maturity, the gadfly larva leaves the body of the animal and falls to the ground or into manure. There it pupates and after 1,5-2 months turns into a full-fledged individual. The cooler the climate in the area, the longer it will take for the parasite to develop. Within a few minutes after the gadfly leaves the chrysalis, he 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 rally is shifted closer to summer. Sometimes the rally continues until the onset of autumn.

The female parasite lays a large number of eggs (from 150 to 500 eggs) on the wool of cattle, but she only lays eggs on cloudless hot days. In cloudy weather and high humidity, insect activity is minimized. The eggs of the subcutaneous gadflies are placed mainly in the udder, abdomen, and also on the sides of the cattle.

The subcutaneous gadfly does not live long, only a few days. After the insect lays 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;
• abscesses;
• refusal to eat;
• problems with 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 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.

At autopsy, large accumulations of hardened capsules from connective tissues can be found in the muscle and subcutaneous layers – these are traces of the migration of larvae through the body of the animal. Also, an autopsy shows severe tissue swelling and damage to blood vessels, along which live larvae can be found. A large number of capsules with parasites are found in the esophagus of cattle.

Diagnosis of hypodermatosis in cattle

Hypodermatosis in cattle proceeds almost asymptomatically at the first stage of larval development, clinical manifestations are typical only for abundant infestation of the individual by parasites. 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 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 administered to 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 oblong seals begin to cover the back of the animals. After 1-2 months, they turn into large nodules. On closer inspection, tiny holes can be found on 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 the larvae of the subcutaneous gadfly in cattle, you can resort to the help of chemicals or remove the parasites mechanically. The most effective means include:

1. «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. Re-treatments are not required.
2. «Gyphlophos“. Method of application – local treatment in the amount of 15-18 ml per individual. A month after the procedure, it is necessary to apply the drug to the skin of the animal again.
3. «Fascoverm“. Dosage – 1 ml per 20 kg of the weight of an individual with hypodermatosis (but not more than 10 ml per animal). The drug is administered subcutaneously once.
4. «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 who have about a month left before calving.
5. «Cydectin“. It is administered subcutaneously once at the rate of 0,5 ml for every 25 kg of weight. Unlike the previous remedy, “Cidectin” is approved for use throughout pregnancy.

The treatment of livestock against hypodermatosis is carried out in the fall, when the activity of adult individuals 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 fistulous passages along with dead tissues. In addition, it is necessary to clean the wounds from pus. In order to stimulate healing, the connective tissue of the diseased individual is additionally excised, and at the same time, compensatory therapy is administered.

Mechanically, the larvae of the subcutaneous gadfly are removed only at a late stage of hypodermatosis. By this time, the fistula openings on the skin reach a sufficiently large size – up to 5 mm, which makes it possible to squeeze the larva 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 larvae of gadflies 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 in cattle are carried out in several steps. The optimal frequency of manual treatment for hypodermatosis is 8-10 days.

Prevention of hypodermatosis in cattle

In order to minimize the likelihood of hypodermatosis in cattle, at least the most basic preventive measures must be followed. So, you do not have to wage a long and exhausting struggle with parasites. The full range of preventive measures includes the following recommendations:

1. Cattle are periodically examined for the presence of fistulas. Particular attention should be paid to the back and lower back area – 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, even non-professionals can detect them. The further course of treatment of hypodermatosis in cattle is determined by the veterinarian.
2. In late August – early September, cattle are recommended to be treated with special preparations for parasites that destroy gadfly larvae at an early stage of development. Treatment of cattle against hypodermatosis should be extended to the entire population, and not just to individuals with suspected disease. It is desirable to complete all procedures before the transfer of cattle to summer keeping.
3. The spread of parasites is limited by the isolation of diseased individuals. If an animal is suspected of hypodermatosis, it is not allowed to graze. So, the gadfly larvae will not be able to go to the pasture and infect the rest of the herd.
4. The likelihood of developing hypodermatosis in cattle can be reduced by shifting 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, 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, pyrethroids and chlorophos are used primarily. The recommended frequency of processing 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 the diagnosis of sick animals in the early stages is difficult due to the latent nature of the course of the disease. Timely treatment of animal skins with medicinal preparations helps to reduce the risk of cattle infection 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 – it is not uncommon for gadfly larvae to pass to humans. In addition, parasites can be introduced into the body of domestic animals, such as dogs.