Estroz sheep

Oestrosis of sheep is an invasive disease, the causative agents of which are the larvae of a winged insect – the gadfly. They parasitize in the nose and frontal cavity of sheep, as well as inside the horns of animals. The disease causes serious damage to the farm and causes suffering to livestock. The article will tell you in detail how the larvae enter the body of sheep and how to deal with the disease.

Sheep infected with estrosis

Causative agent

An insect of the species Oestrus ovis (Sheep gadfly) is directly related to the infection of sheep with estrosis. Its larvae parasitize in the body of animals, passing through all three stages of development. Consider the characteristics of the gadfly:

  1. Its body is about 12 mm long.
  2. The head is large, wider than the body.
  3. The insect is colored light brown.
  4. There are black spots on the body of the gadfly.
  5. The organs of vision are of the faceted type, located on the head, painted in dark green. In males, the distance between the eyes is 3 times narrower than in females.
  6. Adult insects do not have a mouth, as they do not eat. Throughout their life, gadflies live off the reserves that have been accumulated by the larva.

An adult female gadfly lives up to 3 weeks. During this time, she produces about 600 live larvae.

Attention! Oestrus ovis females are viviparous.

The causative agent of estrosis is precisely the larvae of the 1st stage. An adult fertilized female injects them into the nasal passages of grazing sheep on the fly or from the grass. For one injection, she is able to release about 40 live larvae. Not all of them remain in the body of the sheep, because, without having time to attach, some of them fall out. This is how sheep become infected with estrosis.

The further cycle of development of larvae occurs in the nasal, frontal and horn cavities of the animal. There they molt for several months, turning into larvae of the 2nd, then the 3rd stage of development.

The larva of each fly

The larva of each fly

In the spring, when the parasites are fully mature, they leave the body of the sheep, fall to the ground and burrow into it to a depth of about 10 cm. They pupate in the soil, after which sexually mature winged insects form from the pupae. Then they mate, and the whole cycle repeats.

Stages of development of the parasite

So, the causative agents of estrosis are precisely the larvae of the sheep gadfly. They enter the body of a sheep at the 1st stage of development. At this time, their length does not exceed 2 mm. The larvae are painted beige, their oral apparatus is equipped with two hooks, thanks to which the parasites are held on the mucous membrane of the nasal passages of the sheep and move. Parasites penetrate into the cavities of the head – frontal, nasal, as well as into the horns of the animal.

After a few months, molting occurs, after which the parasites reach the 2nd stage of development. The body size of the larva increases 6 times. At the last stage of development, the parasite becomes even larger – its body grows up to 3 cm in length, and its width exceeds 5 mm. There are a number of spines on the underside of the larva, while their upper part is absolutely smooth.

Attention! The gadfly larvae, having penetrated the body of a sheep, eat it from the inside, accumulating nutrients that will later be spent on pupation, mating and flight.

Pathogenesis

The larvae that parasitize in the body of a sheep violate the integrity of tissues and mucous membranes. As a result of damage, edema and inflammation develop. Affected cavities accumulate a huge amount of toxins that enter the bloodstream through damaged capillary walls. Tissues in the places of localization of parasites begin to rot and die.

Attention! The larvae of the sheep gadfly can also affect the central nervous system, as well as the trachea, where they penetrate through the nose.

Parasitic larvae in the body of a sheep

Parasitic larvae in the body of a sheep

Symptoms of the disease

The peak incidence of sheep falls on the warm season, when the flight of insects begins. Toward the end of spring and early summer, when female gadflies give birth and inject larvae of the 1st stage into the nasal passages of animals, the following symptoms of the disease appear in infected individuals:

  1. Anxiety. Sheep experience discomfort in the nasal passages, where parasites have penetrated. Animals sneeze, snort, trying to get rid of discomfort in the nose. They rub this part of the body against various objects.
  2. Discharge from the nose. Already 5-7 days after infection, mucus with an admixture of blood and pus is released from the nasal passages. At this stage, the symptoms of estrosis are similar to those of acute rhinitis.
  3. Later, crusts form in and under the nostrils.
  4. Temperature rise is possible.
  5. Exhaustion. Sheep lose weight due to the fact that they cannot eat properly: breathing through the nose is difficult. Lambs that feed on their mother’s milk are especially affected. Toddlers are forced to switch to pasture, which often leads to digestive problems.
  6. nervous phenomena. If the larvae have affected the membrane of the brain, another characteristic symptom appears – the sheep walk in a circle.

Such manifestations has estrosis at the first stage. Further, the symptoms of the disease are smoothed out, the disease proceeds imperceptibly. This period is in winter. By spring, when the larvae pass the 3rd stage of development and acquire an impressive size, the disease worsens again. Symptoms at the final stage appear in an even more acute form.

Attention! Starting in mid-summer, some sheep may be re-infected. In this case, larvae of the 3rd stage of the last year and larvae of the 1st stage of the current season parasitize in their body.

Methods of treatment and prevention

For the treatment of estrosis in sheep, the following agents are used:

Ivermek for injections

Ivermek for injections

  1. Aerosol Estrosol. The drug is sprayed into the air (60 mg of the substance per cubic meter of the room). It is necessary to carry out processing at least 5 times with a frequency of 1 time per day.
  2. A solution of chlorophos at a concentration of 3-4% is used for irrigation of the sinuses.
  3. A solution of chlorophos in a weaker concentration (0,05-0,1%) is given to drink to sick individuals.
  4. At the initial stage of the disease, it is advisable to use Ivermek (Ivomek) injections, since this drug is able to destroy the gadfly larvae of the 1st stage of development.

Prevention of estrosis includes the treatment of pens with insecticidal preparations, as well as regular cleaning of manure, followed by its burning. Sites where the slaughter and autopsy of dead animals are carried out are paved with asphalt in order to prevent the spread of the disease.

Animals diagnosed with estrosis are not allowed to pasture unless they have been treated. Before pasture for grazing, it is advisable to use repellent preparations to protect animals from gadfly and other insects. In sheep sheds during the spring-summer season, the walls are regularly treated with insecticides.

Estrosis of sheep can cause serious economic damage to the economy, therefore, with the onset of heat, it is important to follow all preventive measures to protect the flock from the sheep gadfly. Timely detection of the disease significantly reduces the risk of death of animals and the spread of insects in the area.

You can bookmark this page

Anna Evans

Author-editor

View all posts by Anna Evans →