How to prevent and control sheep hard tick disease? Detailed explanation of practical technical points

Dense infestation of hard ticks on sheep can cause goats to become emaciated, some pregnant ewes to abort, and mortality is very high among lambs and ewes after lambing.

Expert disease analysis.

(1) Pathogen: The pathogen of this disease is 6 genera of the family Ixodidae, namely Ixodes, Hyalomma, Haemaphysalis, Dermacentor, Rhipicephalus, and Boophilus. Their common morphological features are: the adult body is elongated oval, slightly convex on the dorsal side and flat on the ventral side; there is no distinction between head, thorax, and abdomen, and the three are fused into one body, with a false head at the front end; the false head is composed of a pair of chelicerae, one hypostome, and a pair of palps, with the oral opening between the chelicerae and the hypostome; the ventral side of the body has 4 pairs of legs, each leg composed of coxa, trochanter, femur, tibia, pretarsus, and tarsus, with 1 pair of claws on the tarsus and a claw pad between the claws; the dorsal side of the tick has a scutum, the scutum of the female tick is small, occupying only the front 1/2-1/3 of the back, while that of the male tick occupies almost the entire dorsal side. On the scutum there are various patterns, punctations, and grooves. The sexes are separate, with great difference in size; unfed female and male ticks are about the size of sesame seeds, while engorged female ticks are as large as castor beans, dark red or reddish brown, while engorged male ticks show little change in size.

(2) Epidemiological characteristics: In our country, the distribution of ticks of the family Ixodidae varies with natural conditions such as climate, geography, and landforms in different places. Some ticks are distributed in deep mountain grassy slopes and hilly areas, some in forests and grasslands, and some inhabit livestock sheds and places where livestock stay. Generally, adult ticks overwinter under stones or in cracks in the ground, and the activity season of each tick also varies with the tick family; generally from late February to mid-November there are ticks active on livestock bodies. Sheep infestation by ticks mostly occurs during grazing and feeding, and the parasitic sites are mainly on areas with short and sparse wool.

(3) Symptoms: Direct harm. After hard ticks infest sheep, the mouthparts piercing the skin during blood feeding can cause local damage, tissue edema, bleeding, and skin thickening. Some cases may also be secondarily infected by bacteria, causing suppuration, swelling, and cellulitis, etc. When young sheep are infested by large numbers of hard ticks, due to excessive blood feeding, and because toxins in the tick saliva enter the body and damage the hematopoietic organs, dissolve red blood cells, and form pernicious anemia, the formed elements of the blood drop sharply. In addition, due to the action of toxins in tick saliva, neurological symptoms and paralysis may sometimes appear, causing tick paralysis.

Expert treatment.

(1) Prevention: a. Manually capture or use instruments to remove ticks parasitic on the body surface of sheep. b. Eliminate ticks in sheds; some ticks may inhabit walls, cracks, and holes in sheds, and after spraying or whitewashing with the above therapeutic drugs, seal them with cement, lime, etc. c. Eliminate ticks in nature; according to specific conditions, rotational grazing may be adopted, and after an interval of 1-2 years, the adult ticks on the pasture can be eliminated.

(2) Treatment: a. Subcutaneous injection of avermectin, dose 0.2 ml/kg body weight; b. 0.05% amitraz, 0.1% malathion, 0.1% parathion, 0.05% chlorpyrifos, 0.05% diazinon, 1% carbaryl, 0.0015% deltamethrin, 0.003% fenpropathrin may be selected; c. For spray application of medicinal liquid, emulsions such as 1% malathion, 0.2% phoxim, and 0.25 times parathion may be used to spray the livestock body, with a dose of 200 ml per sheep each time, treated once every 3 weeks.