Effects of age, sex, and post mortem interval on intestinal lengths of horses during development.

This research article investigates how the lengths of different sections of the horse’s intestine vary with age, sex, and the period after death. The study shows that while the overall length of the intestine grows rapidly from mid-gestation to one year of age, then slows down with further increase up to 35 years, the rate and timing of this growth differs for the different sections. Neither sex nor the period after death was found to significantly affect the length of the intestine.

Study Objective and Methodology

• The primary objective of the study was to understand how the lengths of the different parts of a horse’s intestine – the small intestine, caecum, ascending colon, and descending colon – develop over time, from mid-gestation to old age. The researchers also wanted to investigate whether these changes were influenced by the horse’s sex or the period after its death.
• To this end, they measured the lengths of the intestines in 103 horse subjects of varying ages, from foetuses to adult horses, some of them after different time periods post mortem.

Findings

• The researchers found that the total length of the horse’s intestine increased significantly from mid-gestation until around one year of age, but showed very little further increase up until 35 years of age. Thus, the vast majority of the growth in length happens early in the horse’s life, particularly in the first year.
• However, the rates and timings of growth varied substantially for each section of the intestine. The length of the small intestine increased most rapidly in the first month after birth. The caecum grew fastest between the first and sixth months, while the ascending colon extended rapidly between one week and one year. In contrast, the length of the descending colon increased slowly and steadily after birth.
• The periods of most rapid increase in length matched with periods of rapid body growth in the horse, and also with changes in the horse’s diet. This suggests that the intestinal development may be closely linked with these factors.
• Neither the sex of the horse nor the period after death had a significant impact on the length of any part of the intestine.

Implications

• This research contributes valuable insights into the development and growth patterns of the horse’s digestive system. The findings could help vets and horse breeders to support the health and growth of their horses, particularly in the critical first year of life.
• The lack of influence from sex and post mortem interval minimizes potential confounding variables, making the results more reliable and applicable.