The Differences in Histoarchitecture of Hoof Lamellae between Obese and Lean Draft Horses

SIMPLE SUMMARY: Modern research indicates a significant role of obesity in equine health. Obesity is associated with equine metabolic syndrome (EMS), which affects hoof lamellae, causing a painful condition known as laminitis. However, it is not known if obesity itself can cause lamellar failure. Forelimbs from 12 draft horses (six obese and six lean) were acquired. To exclude EMS animals, the insulin concentration was measured in the blood. The hooves were radiographed and assessed histologically. Lamellae differed between obese and lean animals; the damage was found in both groups. However, it is hard to say which group had more laminitic changes: the present study revealed that, in the obese group, 89% of the primary dermal lamella (PDL) was standard, but in the lean group the percentage was only 58%. Therefore, the study did not support the effects of obesity on lamellar failure. The measurements taken indicate that the lamellae are much longer compared to other research studies; this could indicate that the length of the primary epidermal lamellae (PEL) depends on the hoof size. Regardless of previous results, this is the first research showing the anatomy of lamellae of draft horses. ABSTRACT: Obesity is a common problem in horses. The associations between obesity and equine metabolic syndrome (EMS) and between EMS and laminitis are known. However, there is a lack of data on whether obesity itself can affect hoof lamellae. Forelimbs and blood from 12 draft horses (six obese and six lean) from a slaughterhouse were acquired. To exclude laminitis and EMS horses, insulin concentration was measured, and hooves were radiographed. Histological evaluation was performed. The shape of the primary and secondary epidermal lamellae (PEL and SEL) was evaluated, and the length of the keratinized and total primary epidermal lamellae was measured (KPEL and TEL). All horses showed pathological changes in lamellae. In the lean group, the changes were longer SELs, more proliferated and separated PDLs, and less standard PDLs. In the obese group, the changes were a lower number of club-shaped and standard SELs and significantly more tapered SELs. No difference in the shape of PELs and the length of KPELs was noticed. The research did not confirm the effects of obesity on lamellar failure. The measurements taken indicate that the lamellae are much longer compared to other research studies; this could indicate that the length of the PEL depends on the hoof size.