Characteristics of sarcoptic mange and demodicosis in livestock animals

Acariasis: Sarcoptic and Demodectic Mange in Livestock

Sarcoptic mange (sarcoptosis) and demodectic mange, if not timely prevented and treated, lead to decreased productivity, spoilage of hides, and even the death of livestock animals. In the autumn-winter period, sarcoptosis follows an acute course: small nodules and vesicles form in the lesions, severe itching occurs, the skin becomes hyperemic, covered with exudate, thickens, and cracks. In summer, the disease becomes chronic with mild symptoms.

• Quarantine for premises and pastures — 2 months
• Incubation period of sarcoptosis — 2–3 weeks
• Development of the Sarcoptes mite — 15–19 days
• Fecundity of the female itch mite — 40–60 eggs
• Full development of Demodex — 25–30 days
• Survival of Demodex outside the body — up to 9 days

The causative agents of sarcoptosis are dioecious, eyeless mites of the Sarcoptes genus, which are spherical in shape (0.25–0.5 mm long). In females, the 1st and 2nd pairs of legs are equipped with suckers, and in males, the 1st, 2nd, and 4th pairs are. The parasites localize in the epidermal layer of the skin of pigs, horses, camels, goats, and humans. Each species of itch mite requires a specific host; on non-specific hosts, the parasites produce only one generation. The adults (imago) live for 40–50 days, burrowing into the skin, while larvae emerge from the eggs after 3–7 days. The primary localization of the mites varies by species: in pigs — around the eyes, on the cheeks, and ears; in horses — on the head, shoulders, and back; in goats — on the lips, nostrils, and ears; in camels — on the neck and inner surfaces of the thighs.

Demodectic mange affects cattle">cattle and some other animal species. Mites of the Demodex genus have a worm-like body (0.2–0.3 mm long) with a well-developed rostrum and short legs with claws. They live in colonies in hair follicles and sebaceous glands. Females lay eggs within the skin, larvae hatch in 4–7 days, and after two molts, turn into adults. The disease manifests as the formation of dense nodules 2–10 mm in diameter on the neck and shoulder blades, from the center of which bloody fluid is released, followed by hair loss.

A diagnosis of sarcoptosis is made based on symptoms and the results of microscopy of skin scrapings taken strictly before the appearance of serous fluid. Demodectic mange is diagnosed by microscopy of the nodule contents. Treatment for sarcoptosis is carried out according to the protocols adopted for psoroptosis.

Prevention of mange diseases is based on regular cleaning of premises, adequate feeding, protection of the skin from contamination, and avoidance of contact with livestock farms of unknown veterinary status. Newly acquired livestock must be kept in quarantine. Sheep are treated against mange before being moved to remote pastures and upon their return, after the quarantine of newly arrived individuals, as well as before sending animals for herd replenishment.

Cattle Hypodermatosis: Biology of the Pathogen and Specifics of Infection

Warble flies cause severe damage to muscle tissue and skin in the back and lumbar regions. Affected livestock animals lose weight, their milk yield drops significantly, and both meat and hide products are rejected.

The disease is caused by the larvae of the common warble fly and the southern warble fly. The behavior of females during egg-laying differs: the female common warble fly pursues cattle with a loud buzzing sound, causing panic in the herd, and attaches one egg at a time to hairs in the lower abdomen, groin, and paralumbar fossae. The female southern warble fly lands on the ground near the animal, crawls silently onto the limbs, and lays 5–20 eggs on a single hair at once.

First-stage larvae hatch in 6–7 days, penetrate through the skin, and begin their migration through the body. The larvae of the common warble fly move into the fatty tissue of the spinal canal, and those of the southern fly into the submucosal layer of the esophagus. At the final stage of migration, they move under the skin of the back and lumbar region, where they create fistulas. From May to August, matured larvae fall through the fistulas to the ground and pupate. The development of the pupa in the soil takes from 20 to 40 days.

Epizootological data. The source of infection is affected livestock animals. The spread of the disease is facilitated by favorable climatic conditions and high livestock density. In search of animals, females are capable of traveling up to 10 km.

Pathogenesis. During the migration period in the animal's body, larvae traumatize its tissues, facilitate the penetration of microflora into the organism, and exert a toxic effect on it.

Symptoms. At the stage when larvae reach the skin of the back and lumbar region, single or multiple firm, painful nodules and fistulas form on the animals.

Diagnosis. Diseases are diagnosed during the winter-spring period by inspection and palpation of the back and lumbar region of the animals for the presence of nodules and fistulas.

Control measures and prevention. The primary method for eliminating hypodermatosis is the destruction of larvae within the animals' bodies. To this end, after the end of the gadfly flight season, cattle cattle are treated with Ivomec. The preparation is administered subcutaneously at a rate of 1 ml per 100 kg of live weight. In spring, livestock are thoroughly examined, and if nodules are detected, they are treated again. During the gadfly flight season, animals are grazed in cloudy, windy weather or only at night.

Gasterophilosis of horses is a disease that causes damage to the digestive tract and a reduction in the productivity of animals.

The pathogen is represented by the larvae of gastrointestinal botflies: *Gasterophilus intestinalis*, *G. nasalis*, *G. pecorum*, *G. nigricornis*, *G. meridionalis*, etc. Their length upon entering the organism is 0.58—1.48 mm, and at the moment of exit, it is 12—21.5 mm; the length of winged botflies ranges from 9—13 mm. The mouth apparatus is underdeveloped.

Insects fly from June to September and live for 12—40 days, fueled by substances accumulated during the larval stage. Females of *Gasterophilus intestinalis*, *G. nasalis*, *G. nigricornis*, and *G. meridionalis* lay eggs on the hair of horses, while *G. pecorum* lays them on grass. Over its lifetime, one female produces 100—1000 eggs. After 1—2 weeks, stage I larvae hatch from the eggs and reach the oral cavity of the horse through various means (crawling, migrating through tissues, being ingested by animals while grooming their skin, or together with grass). Further, the larvae penetrate the tissues of the cheeks, gums, soft palate, tongue, and pharynx, and then move into the gastrointestinal tract, where they undergo stage II and III of development. They remain in the animals' bodies for 6—7 months, after which they are excreted with feces and pupate.

Figure 37 – Development biology of the gasterophilosis pathogen. Examine the stages.

Epizootological data. Horses become infected in the pasture during the gadfly flight season and can be affected by several species at once.

Pathogenesis. On the mucous membrane of the gastrointestinal tract, at the sites of attachment of the botfly larvae, depressions form, inflammatory processes occur, and ulceration of the mucous membrane takes place.

Symptoms. With significant infestation, animals appear emaciated, exhibit signs of chronic gastroenteritis, and frequently experience colic.

Lice are permanent ectoparasites living on specific hosts and feeding on blood. The lifespan of lice is 3-4 weeks. The female lays 50-100 eggs (nits), from which larvae hatch in 10-18 days, undergoing three molts and reaching the sexually mature stage in 10-14 days.

Epizootological data. The disease is registered everywhere. Infection occurs through contact, care items, bedding, and harness. The spread of the disease is facilitated by inadequate feeding of animals, high humidity in facilities, and irregular cleaning. Outside the organism, parasites can survive for 110 days.

Symptoms. Sick animals are restless and scratch their skin. As a result, their hair breaks and becomes ruffled, and the skin gradually coarsens, becoming rough and folded. Such animals lag in growth, and their body condition score decreases.

Diagnosis. Siphunculatosis is diagnosed based on the discovery of sexually mature insects or their nits on the animals' bodies.

Control measures and prevention. During the warm season, affected animals are sprayed with a solution of Stomosan or other agents; in the cold season, they are treated with dust or injected with Ivomec (avermectin). In summer, the treatment is repeated after 10-12 days, and in winter, after 14-18 days.

To prevent the disease, livestock facilities must be cleaned regularly; high humidity must be avoided; the cleanliness of the animals' skin must be monitored; and the order of herd composition must be observed.

Knowledge of the fundamentals of veterinary medicine will allow students of the Zootechnics specialization to understand what pathologies may arise in livestock and domestic animals during their breeding and intensive exploitation. The complex of veterinary measures consists of the prevention of non-infectious and infectious diseases, and in the event of their occurrence, of therapeutic techniques and measures for their elimination. Furthermore, a number of infectious diseases pose a serious economic threat not only to a specific farm but also to a settlement or even an entire region.

Veterinarians and zootechnical specialists always work together. It is the zootechnicians who monitor the feed base and housing conditions, as well as keep records of productivity, and the process of obtaining breeding and commercial livestock animals and poultry. The role of veterinary specialists is the prevention and management of diseases, and the preservation of the health of young stock, breeding, and productive animals. Only full-fledged cooperation will allow obtaining high-quality products that are safe for consumers.

Numerous facts indicate that the greatest harm during measures to prevent or eliminate infectious animal diseases is caused by violations of the requirements of the RF Law "On Veterinary Medicine" and the veterinary rules and instructions developed on its basis for the protection of farms, ranches, and herds from the introduction of infectious agents, as well as the rules for the destruction of disease pathogens in the external environment. Compliance with the requirements of veterinary legislation is mandatory for the heads of livestock farms of all forms of ownership and for all animal owners.

The development and implementation of more advanced methods and means for the prevention and treatment of animal diseases, based on modern achievements in veterinary medicine, is relevant. The rational application of a number of veterinary measures at specific biological stages of animal life will significantly increase the profitability of livestock farming.

The knowledge gained on the basics of veterinary medicine will help livestock breeders understand the need to comply with veterinary and sanitary requirements, standards, and rules for organizing technological processes in livestock farming, techniques for providing emergency first aid to sick animals, and will contribute to protecting the environment from pollution.

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