In course of realized in the conditions of the Republic of Belarus research there were studied the relations of the most widely spread helminthes and protozoan which infest in gastrointestinal tract of dogs with the normal microflora of small intestine and large intestine. Research results showed that in the conditions of single-agent infestation and associative parasitic disease of dogs caused by Toxocara canis, Toxascaris leonine, Dipylidium caninum, Uncinaria stenocephala, Taenia sp., Isospora ochioensis, Isospora canis and Eimeria canis in small and large intestine of sick animals there was seldom stated the changes of quality and quantity composition of microflora. In the conditions of mixed agents infestation the microflora composition changed more intensively

Searching for new, effective and safe methods of treatment of hookworm disease (ancylostomatidosis) of dogs caused by Ancylostoma caninum and Uncinaria stenocephala was realized in the conditions of the Republic of Belarus on the basis of studying of spices composition and dissemination of Ankilostomatidae, age-specific and seasonal disease dynamics, testing of medical and preventive preparations Univerm and Fenbendazol. In the Republic of Belarus Ancylostoma caninum was stated 4,2% of studied cases and Uncinaria stenocephala – in 14,3%. The maximum intensity of the invasion was stated in summer and autumn periods: in cases of individual keeping – 19,4%; in cases of group keeping the disease transformed into enzootic form with 66,7% affect. In winter period there was the lowest invasion – up to 1,4%. The preparation Univerm administrated twofold with feed in dose of 0,1 mg/kg with 24 hours interval proved to be highly effective therapeutic agent with extensefficiency100%. Anthelmintic Fenbendazol administrated once with feed in dose of 0,005 g/kg proved to be highly effective with extensefficiency 80% and intensefficiency 98,84%. Hematological indexes of sick dogs showed the evidence of erythropenia (4,30-4,80 x 10E12/l), hemoglobinemia (113-119 g/l) and eosinophilia (up to 11%), as well as the increased quantity of leukocytes on 5,46% - 23,61 %, and the lowered quantity of lymphocytes on 15,84 % in comparison with healthy animals indexes

Evaluation of influence of monoinvasions and mixed parasitoses on quality and quantity composition of microbiocenosis of gastro-intestinal tract of carnivore was realized in the conditions of the Republic of Belarus. Changes in intestinal microflora of gastro-intestinal tract of dogs with monoinvasions and associated parasitic diseases in comparison with indexes of healthy animals were typical for disbacteriosis and took place towards the reduction of quantity of normal intestinal microflora (bifidobacteria and lactobacteria) and increasing of transient microorganisms: aerobic bacilli, micromicetes, proteus spp, staphylococci, streptococci.