Horse breeding  is one of the main branches of animal husbandry, that’s why the problem of it’s revival is one of the most actual for today. Different diseases, especially parasitic, discourage of intensive development of horse breeding that in the most cases run chronic and cause significant damage. Among parasitic diseases of horses the special place take Nematodes of digestive tract, namely Strongilatosis.

The objective of our investigations was studying and spreading  Strongilatosis of horses  in the conditions of SSRC BNAU, to set the specific structure of Strongilatosis and effectiveness of antihelmintics Nemasectin in this invasion.

The investigations were provided on the base of SSRC and also in laboratories of parasitic and pharmacy department of BNAU. For scatological investigations of horses there were used the general in veterinary practice method created by Darling in modification of G. Kotelnikov and V. Khrenov. There were investigated 25 samples of feces from horses of different breeds and age groups.

Due to the fact that to determine the specific affiliation of Strongilate eggs’  anatomy almost impossible we conducted the culturing of eggs  to invasive larvae with perfected method, using pigment.

The experiment in studying antihelmintic effectiveness of Nemasectin was conducted on horses from 1 to 8 years of age, that were spontaneously infested by Strongilit. With this purpose for experiment 12 horses were chosen and we also formed 2 groups of animals (6 heads in each) - experimental and control.

For animals of experimental group Nemasektin was used, which was given inside one time in a rate of 0,2 mg per kg of body weight (2 g of paste per 100 kg of body weight). Animals of control group didn’t get the antihelmintics. Before giving the drug and also 12 days after the last application of antihelmintics  investigations were conducted. All animals in both groups were in the same conditions of feeding and keeping.

In order to study helminthological situation in housekeeping were conducted feces investigations for availability of parasitic eggs. The amount of eggs in 3 drops of  flotal  liquid was from 34 to 154 samples. Eggs were found  in 80 % of animals.

For differentiation of strongilit and determination the specific structure of parasites we used perfected by O. Sheremet  diagnostic  method with using pigment. On the results of differential diagnostic of Strongilit in horses in the conditions of SSRC of BNAU there were founded 6 species of parasites, family Strongylidae: Strongylus equinus (ЕІ=32,0 %), Strongylus edentatиs (ЕІ=28,0 %),family Cyathostomidae: Cylicocyclus nassatus and Cylicocyclus leptostomum (12,0 %), Cylicostephanus longibursatus and Cylicostephanus minutes (8,0 %).

In this experiment all horses were infected for 100 % by Strongilit eggs with  the  intensity of invasion from 42,0 to 65,0 samples of eggs in 3 drops of flotal liquid.

On the 12^th day after the last application of antihelmintic drug we took samples of feces again and defined that used drug has 100% effectiveness against Strongilatosis.

Thus, we can say that affection of horses in SSRC of BNAU by Strongilatosis was 80 %. Intensity of invasion  was 65,4 samples of eggs in 3 drops of flotal liquid. Horses were affected by helmintics of 2 families namely Strongylidae: Strongylus equinus (ЕІ=32,0 %), Strongylus edentatиs (ЕІ=28,0 %) and family Cyathostomidae: Cylicocyclus nassatus та Cylicocyclus leptostomum (12,0 %), Cylicostephanus longibursatus and Cylicostephanus minutes (8,0 %). The antihelmintic Nemasektin is highly effective  drug against horse strongilit. One time individual using of Nemasektin inside in a rate of 0,2 mg per kg of body weight( 2g of paste per 100 kg of body weight) provides deliverance horses from Strongilit invasion for 100%.

Key words: strongilyaty intensity of invasion, extent of infestation, ekstens- and intens, nemasektin, family Strongylidae, family Cyathostomidae.