Horses putting on weight are more than twice as likely to develop laminitis than their counterparts who are maintaining or losing weight, recent research suggests.
The risk posed by weight gain was among three risk factors consistently linked to higher rates of laminitis in the major British study.
The other were a previous history of laminitis, and lameness or soreness following routine shoeing or trimming.
The findings of the research, conducted by the Animal Health Trust in collaboration with the Royal Veterinary College and Rossdales Equine Hospital, have been published in the journal BMC Veterinary Research.
The findings provide compelling evidence that laminitis develops significantly more often after horses and ponies gained weight rather than when they lost or maintained weight.
The study was run over 29 months between 2014 and 2016, with horse owners and caregivers recruited nationally across a variety of equestrian and veterinary media platforms.
Participants submitted a baseline management and health questionnaire, supplemented with regular consecutive follow-ups, as well as the separate reporting of laminitis episodes.
In all, a total of 6953 questionnaires representing 1070 horses and ponies were submitted. These covered an accrued time of 1068 horse years at risk.
In the study, weight and body condition were regularly estimated and recorded by the horse and pony owners, with more than half the participating owners opting to use a custom-designed online weight tracker.
Worryingly, weight gain was often occurring unintentionally, even when owners were aiming for weight maintenance or loss.
This reveals the importance of consistent weight and body-condition recording, so that undesirable weight gain can be recognised before it harms health.
The researchers suggest owners should review their animal’s current diet, exercise and health management routines as soon as undesirable weight gain is detected and take appropriate action.
The work also identified high-risk groups found to be particularly susceptible to developing laminitis.
Owners of British native pony breeds and their crosses were found to be at higher risk than the general horse population.
A high risk of future laminitis episodes was identified in all animals shod or trimmed at intervals of more than 8 weeks, and those with a lengthy return to soundness following the most recent episode.
Earlier recognition of laminitis, along with adequate and prompt veterinary attention, farriery support and diagnostic testing of underlying metabolic disorders should give animals the best chance of recovery and a potential to reduce the risk of future episodes.
Features of diet, grazing management and health were also associated with the development of laminitis and require further investigation.
For example, horses and ponies with short-term morning-grass access, and those that wore grazing muzzles for only part of their grazing time were more likely to develop laminitis. These findings suggest that some grazing management interventions were not optimal at preventing laminitis.
“This is one of the largest, and the first, online laminitis studies where we collected regular information from the same group of owners in real-time,” said Dr Dee Pollard, of the Animal Health Trust, who worked on the study, which was funded by the charity World Horse Welfare.
“We assessed the relationship between laminitis and many potential management and health factors and identified those more likely to be present before a laminitis episode was reported.
“We now have good evidence to develop laminitis prevention guidelines, and a number of different avenues to explore in the future.
“We cannot emphasise enough how important systematic and regular weight and body condition monitoring are. It’s very easy to miss weight gain when you are just relying on your eyes and you see your horse or pony every day.
“You need to get hands on, feel for the fat deposits and take measurements. Remember, the figures don’t lie.”
World Horse Welfare’s head of support in Britain, Sam Chubbock, acknowledged that effective management of a horse or pony’s weight can be challenging.
“It is important that owners are aware of the increased risks associated with excess weight.
“This breakthrough study has highlighted which types of equines are most at risk and how important it is that owners and carers regularly measure and monitor their horse or pony’s condition throughout the year so they are able to spot changes as early as possible and alter their management accordingly.
“If anyone is concerned about their horse’s weight then their vet is best placed to advise on appropriate steps.”
The Animal Health Trust, with ongoing support from the Margaret Giffen Charitable Trust and World Horse Welfare, aims to develop up-to-date recommendations to help prevent laminitis development.
It will continue to investigate some of the identified risk factors, such as weight gain, to learn more about their impact on laminitis, and equine health in general.
Identification of modifiable factors associated with owner-reported equine laminitis in Britain using a web-based cohort study approach
D. Pollard, C.E. Wylie, K.L.P. Verheyen and J.R. Newton.
BMC Veterinary Research 2019 15:59 https://doi.org/10.1186/s12917-019-1798-8