Positive and negative aspects of animal therapy using are discussed. Research of 30 case studies is displayed that pet therapy is a good therapeutic tool in approximately 60% of cases. To diagnose possible problems in families which have got a dog as a "therapist" for the child suffering from some or other form of dysontogenesis, the author suggests theoretical model of human-animal relationships. This model includes definition of heterospecific group, necessary condition of its creation and sufficient condition of its existing, types of relationships in heterospecific group, psychological phenomena arising in such group, and dynamics of heterospecific group functioning. The methods most relevant to research of heterospecific groups and correction of infringements in these groups are described. For a diagnostic basis, the following classification has been accepted: (1) infringements from the animal; and (2) infringements from the person. Correction of infringement for the purpose of restoring stability in the group is shortly described. (Contains 9 figures and 1 footnote.)