Microanatomical development of the equine kidney and defects associated with intra-uterine growth retardation

Using novel stereological techniques, this study attempts to establish norm al organogenesis of the equine kidney in utero and into the post partum per iod, and the effects of adverse intra-uterine conditions on fetal developme nt. At birth, renal maturation appears to be more advanced in Ponies compar ed to Thoroughbreds (TB's), and the study has highlighted differences in no rmal kidney development between native Ponies and "un-naturally" selected T B's. The data presented supports previous physiological studies. Results al so showed that compared to other species, organ development continues for a relatively longer time postnatally in the horse, Until completion of organ ogenesis the horse may be at risk of exceeding its functional capacity espe cially during periods of stress or excessive physiological demands which ar e placed on the developing racehorse. Altered/deficient organogenesis seen in the intra-uterine growth retarded (IUGR) animals may help to explain som e of the physiological incompetence and the increase in morbidity and morta lity seen in this group of animals by equine clinicians.