Three risk factors consistently tied to higher laminitis rates in horses


Three risk factors are consistently linked to a higher risk of laminitis developing in horses, British researchers report.

A previous history of laminitis, lameness or soreness following routine shoeing or trimming, and recent weight gain were the key factors linked to a heightened risk of laminitis development.

Danica Pollard and her colleagues set out in their study to identify factors associated with laminitis in horses and ponies in Britain using the internet to reach horse owners.

The study team, writing in the journal BMC Veterinary Research, noted that few robust studies had been conducted to ascertain the animal and management-level factors that contributed to laminitis development.

The researchers were particularly interested in evaluating modifiable risk factors that had previously been identified in a case-controlled study.

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.

The median number of submissions per animal was 4, with a range of 2 to 9. The median time between submissions was 38 days.

Analysis identified 16 variables associated with laminitis development.

Those linked with higher rates of laminitis included weight gained during the study; native pony breeds versus all other breeds combined; a previous history of laminitis, particularly when previous episodes were not veterinary-diagnosed; longer recovery periods following the most recent laminitis episode; recent use of steroidal or non-steroidal anti-inflammatory drugs; lameness due to soft tissue injury; benzimidazoles used for the most recent worming as opposed to products containing macrocyclic lactones such as ivermectin; lameness or foot soreness following the most recent trimming or shoeing; and a trimming or shoeing frequency greater than eight weeks.

Risk factors were also identified around turnout and grazing management. Those with short-term access to grass in the mornings as opposed to accessing grass at other times of the day and/or night were at higher risk; as were horses who wore grazing muzzles only part of the time versus those who did not use them at all, or used them the whole time during grazing.

Spending 12 hours or less stabled carried a higher risk factor than those stabled more than 12 hours, as did being transported in the previous year mainly due to moving yards versus being transported for other reasons or not at all.

Turning to supplementary feeding, the feeding of ryegrass forage (hay or haylage) carried a higher risk than forage of other grass types (for example, meadow grass or timothy) or no supplementary forage.

Animals whose turnout area bordered woodland had a reduced rate of laminitis compared to animals not turned out adjacent to woodland.

The study team said the work had identified an association between a number of animal and management-level factors and owner-reported laminitis.

“It has corroborated the association between previously identified risk factors and laminitis and identified potential management-related interventions and risk group identifiers which should be targeted for future detailed study.

“There is now consistent evidence that weight gain, a previous history of laminitis, and soreness following routine hoof care are associated with laminitis development, as the same factors were found to be associated with laminitis in a previous case-controlled stud.

“Priority targeting of the more common exposures that are also most-modifiable, such as weight gain, will have the highest impact on disease incidence.

“These results serve as a sound evidence-base towards the development of strategic recommendations for the horse/pony-owning population.”

They said the creation of evidence-based recommendations, and their translation to practical interventions, should contribute to a reduced laminitis rate in Britain, while risk groups identifiers will distinguish animals for which the interventions would be of particular relevance.

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


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