The larvae of the subcutaneous gadfly, parasitizing on cows, cause cattle hypodermatosis. This seasonal disease is characteristic of the whole territory of Russia. Pathogens cause economic damage to livestock and meat industry. Acquaintance with the mechanisms of disease in cattle allows for effective prevention of invasion - the penetration of parasites into the body.
Description of the pathogen
Hypodermatosis in cows causes two types of parasites: the line - a simple subcutaneous gadfly and the esophagus - gadfly, parasitizing in the southern regions of Russia. Having reached childbearing age gadfly (imago), outwardly resemble a large bumblebee. The rounded body, having up to two centimeters in length, is covered with a layer of thick red-yellow and black hairs, and has sweeping wings of light-gray outflow. The adults of the gadfly do not eat at all and they have no mouth openings.
For cattle, only fertile females are dangerous; they lay about 800 oblong eggs and die immediately afterwards. The female of the row pastes eggs with the fur of the hind limbs and the abdomen of the animal, and the esophagus with the coat of the forelimbs and dewlap.
Larvae development stages
For 5-7 days larvae hatch with larval hooks (1st stage larvae) from eggs. Reaching a length of 0.6 mm, they settle on the skin of the animal and begin their penetration. Line - in the spinal canal, esophagus - in the esophagus. Having stayed in the organs of the cow for about six months, the larvae continue to migrate in the form of connective tissue capsules to the back and waist of the animal. During this period, parasites need oxygen, so they make through holes in the skin of cattle.
After a week, the larvae molt, and the 2nd stage of development begins. Now they reach a length of 20 mm and undergo another molt. After 3-4 weeks, the parasites reach the 3rd stage of development, at which they increase in size up to 28 mm and can freely creep out of the capsules. Settling on the surface of the earth, they pupate for 4-6 weeks and transform into imago.
Sick animals - the source of the invasion
The main carrier of hypodermatosis is cattle. The peak of animal infection occurs in the summer, when insects go through egg laying stages. Spring exacerbations are not excluded. Infections with hypodermatosis are most susceptible to cows aged 1-3 years. Older animals are sick less often, as their skin is denser and their tissues are rougher. With inadequate feeding of livestock, the risk of adult disease is significantly increased.
Climate conditions affect the activity of hypodermatosis pathogens: strong winds, rains, heavy and wet soils.
A weighty factor affecting the number of gadflies and the development of hypodermatosis in cattle is the degree of density of the animals. A cow can become infected with a cattle patient brought to the farm without proper thorough examination. Persistent acquired immunity is an excellent protection of animals against larvae bearing hypodermatosis.
Animals anticipate danger
During the period of increased gadfly activity and infection with hypodermatosis, animals may feel approaching danger. Therefore, the owner must pay attention to their behavior.
External distinctive signs in cows upon the onset of infection:
- increased anxiety of the animal;
- swelling, itching and soreness of certain skin areas;
- suspicious thinness with regular meals;
- reducing the amount of milk from a cow;
- obvious blood leaks on the body of the animal;
- in the lumbar or dorsal region, characteristic bulges (grooves), hard to the touch;
- contamination of wool and subcutaneous layer by purulent masses released from wounds;
- paralysis of limbs, when insects enter the spinal section of the animal.
Suspension and loss of appetite
The first symptoms of a cow infection are allergic, toxic and mechanical irritation. They lead to a local inflammatory reaction with obvious painful symptoms. Bleeding wounds appear on the animal's body, eventually becoming covered with scabs.
When larvae of the 1st stage are introduced into the muscular layer of the esophagus and into the spinal canal of a cow, they are denied food and swelling of the digestive tract of the animal occurs. In this case, the cattle becomes hard to swallow, there is belching. You can notice stretching the neck and wobbly gait.
At the stage of introduction of the gadfly into the almost impassable layer of skin, distinct, hard nodules appear, the number of which can be up to 200 pieces. The greatest number of nodules is concentrated along the spine. The danger of their localization is that during the vital activity of the larvae a mass of toxic substances is released. During this period, the animal is prone to severe intoxication, which leads to the inhibition of vital functions and the gradual death of muscles.
With the manifestation of the above symptoms in livestock, it is necessary to carry out the immediate destruction of the larvae that have penetrated into the organism of animals. The work is carried out in two stages.
The early stage is carried out from mid-September to November with insecticides. When more than 5 nodules are found on the cow's body, chlorophos is used. Using a special dispenser, the drug is sprayed along the ridge of the animal.
During the late stage, from early March to September, larvae that have reached stage 2-3 of development are being utilized. 10 grams of 4% chlorophos powder is mixed with 1 liter of water and the affected skin of the animal is treated with this solution.
Drug treatment of hypodermatosis is widely used. Drugs such as dioxaphos and fenthion should not be used during lactation of animals. These medicines can release dangerous toxins and impair the properties of milk. Antibiotics that contain avermectin, are able to completely destroy the subcutaneous larvae.
Preventing invasion is easier than curing.
Preventive work to prevent illness in animals should be carried out at all stages of the herd's life. Grazing should be carried out mainly in the morning and evening, when the activity of pathogens decreases. In areas with a high risk of infection with hypodermatosis, cattle are treated with pyrethroid preparations and chlorophos. Such prevention should be carried out every 20-30 days for all animals, without exception.
Scaring away adult individuals of gadfly from cows is carried out by intracutaneous administration of the drug "Aversect". The stall where livestock is kept, periodically needs to be treated with biothermal means. Manure must not only be collected, but also decontaminated. In the summer, animals should be treated with pyrethroids (1 time in 20 days), these include K-otrin, butox, stomazan and ectomin.
Hypodermatosis of cattle is a serious parasitic infection, which leads to intoxication of the whole system of the body and reduces the productivity of an infected cow. Contribute to the fight against the disease - share the article with your friends.
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