Leukocyte indices in dogs with acquired primary hypothyroidism

According to global statistics, hypothyroidism in dogs is a widespread disease. However, due to certain difficulties in conducting laboratory diagnostics, as well as the cross-species specificity of such indicators as thyroid-stimulating hormone, thyroglobulin autoantibodies, prompt diagnosis and differentiation of hypothyroidism in dogs in the practice of a veterinarian is difficult. Thus, it is relevant to search for secondary auxiliary methods of diagnosis and detection of hypothyroidism in dogs based on a set of indicators and diagnostic coefficients-indices. Since hypothyroidism causes an immune system malfunction, such indicators may be leukocyte indices characterizing indicators of nonspecific cellular immunity and the organism reactivity.

The purpose of the presented study was to evaluate the leukocyte indices of dogs with primary acquired hypothyroidism for further use in order to facilitate the diagnosis of thyroid dysfunction in dogs, as well as to study the formation of an immune response in different animal species, followed by its possible use in experimental studies of the influence of various factors on the nonspecific cellular immunity of animals and humans.

The blood leukogram parameters of 15 dogs with established primary hypothyroidism were evaluated before the start of replacement therapy and compared with similar leukogram parameters of clinically healthy dogs (n = 19).

There was a significant increase in the leukocyte intoxication index (p ≤ 0.05), the leukocyte shift index (p ≤ 0.1), the nuclear index of G. D. Dashtayants (p ≤ 0.05) in the group of hypothyroid dogs compared with the group of healthy dogs (n = 19).

An increase in the leukocyte intoxication index may indicate the development of inflammatory processes and an increase in the degree of endogenous intoxication of the body. An increase in shift index in the blood of sick dogs may indicate active inflammatory processes, as well as a decrease in the degree of immunological reactivity in hypothyroidism. The increase of nuclear index of G. D. Dashtayants characterizes an elevation in the rate of regeneration of neutrophils and monocytes and an increase in the duration of circulation of these types of leukocytes in the bloodstream. This, in turn, indicates a chronic process. Thus, when detecting a simultaneous increase in the blood of a dog of such leukocyte indices as mentioned above, attention should be paid and included in the list of possible differential or concomitant diagnoses of hypothyroidism. In the future, the study is planned to expand with an increase in the sample of animals, record and analysis of individual physiological conditions and breed characteristics, as well as dietary characteristics, correlation with the severity of the condition, analysis of life expectancy and survival.