Morphological and biochemical changes in the blood of horses naturally infected with Gasterophilus sp. larvae.

Gasterophilus sp. constitute a group of specific parasites, which larval forms are found in horses and other phylogenetically related species--donkeys, mules and zebras. Their invasion is associated with marked fluctuations of hematological and biochemical blood parameters, including the activity of many enzymes and the electrolyte concentration. The purpose of the study was to analyze changes in selected biochemical and morphological blood parameters of horses infected with botfly larvae. The experimental group was formed of horses infested by Gasterophilus sp. larvae whereas the control group consisted of noninfested horses. The study was performed in two periods: at the beginning and at the most advanced invasion. Significant differences between horses at early and late stage of invasion were found in terms of erythrocyte parameters. Mean red and white blood cell counts and mean hemoglobin concentration were lower in horses with late invasion compared to those with the invasion at its early stage. The values of all the aforementioned erythrocyte parameters remained within the reference limits for both groups of horses. Moreover, both in horses infected with botfly larvae and in those from the control group, biochemical parameters studied did not exceed the respective reference limits. Our results suggest that larvae of botfly which colonize the gastrointestinal tract have relatively insignificant influence on the basic hematological and biochemical parameters of horse blood.