A research project funded by equine charity The Horse Trust has found that lameness is the most common reason for euthanasing a geriatric horse.

According to the charity, this research is the first in the UK to provide data on the causes of death in geriatric horses. Although post-mortem studies have provided some data regarding causes of death, "old age" was previously reported as a common reason for the euthanasia of adult horses.

The research was carried out by Joanne Ireland at the University of Liverpool and led by Dr Gina Pinchbeck. Ireland surveyed horse owners living in the North-West and Midlands areas of England and North Wales who have a horse aged 15 years or older. 918 owners of geriatric horses were followed in a cohort study and 118 mortalities were reported during the 18 month follow-up period, of which 111 were euthanased.

The researchers found that 24% of horses were euthanased due to lameness; an additional 12% were euthanased due to laminitis - a common cause of lameness. After lameness, colic was the next most common cause of euthanasia, with 21% of owners citing this as the main reason.

In an earlier stage of the project, the researchers had found that half the geriatric horses surveyed suffered from lameness, but only 24% of owners reported the problem.

Dr Pinchbeck said: "Although lameness is common in older horses, this is the first study to quantify its contribution to their mortality.

"Owners are often missing the early signs of lameness in their horse, which means the condition isn't being managed and may deteriorate faster."

Dr Pinchbeck said it would be useful to carry out further research into lameness in geriatric horses to find out the main causes of lameness and how these may be prevented or treated.

The research team also found that half of the horses euthanased were suffering from concurrent health problems and these influenced the owner's decision to euthanase in 43% of cases. The most frequently reported additional health problems were musculoskeletal problems, such as arthritis.

The mortality rate among the horses surveyed was 11 per 100 horse-years at risk, meaning that if 100 geriatric horses were followed for a year, an average of 11 would die. The mortality rate for horses over 30 years of age was over five times the rate than in horses aged 15 - 19 years.

Jeanette Allen, Chief Executive of The Horse Trust, said the data provided by this research is likely to provide useful information for both horse owners and vets to enable them to improve the welfare of older horses. She said: "As there are a significant number of geriatric horses in the UK, it is vital that we understand more about the health problems that affect them. We hope that more owners of older horses will give their horse an annual health-check to enable the horse to have a longer, healthier life."

The research was published in the September 2011 issue of Preventive Veterinary Medicine.

PS: Whilst you're here, take a moment to see our latest job opportunities for vets.