Older horses are vulnerable to a diversity of diseases that are impacted by age. These include pituitary pars intermedia dysfunction (PPID), dental disease, osteoarthritis, strangulating colic, and laminitis. The authors of this report wanted report the reasons for death in older horses and determine what affect, if any, PPID had on horse mortality. They included horses older than 15 years and defined these animals as geriatric.
The average age of horses that died at the facility was 26 years, with a range of 16-37 years. The most common cause of death was colic, followed by “old age” and lameness (excluding laminitis). The diagnosis of old age revolves around decisions related to welfare, including lethargy, inability to eat adequately due to dental disease, arthrosis, and no group or social interaction. In this study very few of the horses experienced chronic weight loss, which has been reported in other studies to be an important cause of elective euthanasia. They suggest that management, including frequent preventative care, might explain these differences. It is also worth noting that chronic respiratory diseases, such as severe asthma (heaves) were not common in the region.
Of interest was that the authors found that horses with a diagnosis of PPID lived longer than those without that diagnosis. Also, they reported no difference in lifespan between positive animals that were treated compared to positive horses that were not treated. They did not confirm a link between a PPID diagnosis and death due to PPID related diseases, such as laminitis, weight loss and chronic infections. There are likely issues related to the accuracy of the PPID diagnosis due to seasonal timing of testing and related normal ranges. Treatment of PPID with pergolide may have resulted in improvement in individual horse welfare.
Retrospective analysis of cause of death at an equine retirement center in the Netherlands over an eight year period. Van Proosdij and Frietman, published in the Journal of Equine Veterinary Science (2021), doi: https://doi.org/10.1016/j.jevs.2021.103824