Effects of Horseshoes on Dynamic Hoof Angles

In collaboration with faculty at the University of Calgary, researchers from New Bolton Center in Pennsylvania conducted an experiment to measure differences in dorsal-palmar and medial-lateral hoof angles at midstance after applying six different types of shoes and walking the horses over tracks of rubber pavers, turf and sand.

Six horses actively being used in competition without signs of lameness were alternately shod in a randomized cross-over manner with flat; toe-, medial- or lateral-wide; egg bar and wedged egg-bar shoes. An accelerometer was attached to the dorsal hoof wall to measure hoof orientation while standing and at midstance.

On the hard surface, dorsal hoof angles were similar when standing and at a walk’s midstance. All the shoes on both deformable surfaces significantly affected hoof angles at midstance, with all combinations pitching the hoof forward for an increase in hoof angle. All the shod conditions also revealed lateral sinking of the hoof at midstance.

Dorsal hoof angle increased the most on both turf and sand, with egg bars producing a greater hoof wall increase than wedged egg bars. The egg bar also increased lateral sinking of the hoof into the sand surface. As one would expect the medial-wide shoe increased lateral sinking. The lateral-wide shoe produced a slight increase in medial sinking on the sand, but only slightly decreased the lateral sinking seen on the turf with the flat shoe.

 —  Reilly PT et al. EVJ 2023:13990e

Lameness Exams in Gaited Icelandic Horses

Examining gaited horses for lameness often presents unique challenges not encountered with non-gaited horses. Researchers in Iceland described how gait and movement change in response to a mild lameness in comparison to what is normally seen in non-gaited horses.

They measured upper body and limb kinematics using 11 inertial measurement units attached to the poll, withers, pelvis, limbs and hooves in 10 non-lame horses before and after inducing a mild lameness using a sole pressure shoe. The measurements were obtained in hand at the walk and trot and while ridden at the walk, trot and tolt.

Lameness significantly increased vertical movement asymmetry at the walk and trot and subtly changed temporal elements of the gait in a manner similar to what one expects to see in non-gaited horses with the head’s vertical range of motion increasing more at the walk and trot in hand compared under saddle. However, there were few measurable changes seen at the tolt. The authors suggest movement asymmetry, particularly of the head, is less useful to identify lameness at the tolt and lameness exams should primarily focus on the walk and trot.

—  Smit IH et al. EVJ 2023:13998

Effects of Shoeing on Hoof Landing

In consultation with a Dutch scientist, the faculty of the Leipzig University in Germany conducted an experimental trial to examine the effects of trimming and shoeing on hoof landing duration, initial contact location and angle of 10 sound horses while walking and trotting in a straight line on concrete.

Measurements were obtained using an inertial measurement sensor attached to the dorsal hoof wall, and the horses were examined barefoot, after trimming, with lateral weights and 5-degree medial wedges attached to the hoof and with plain steel, aluminum, egg bar and lateral extension shoes.

There was considerable variation in the measured parameters both within and between horses. Landing duration was shorter at the walk than the trot, but there were no significant differences in initial contact location or angle between the two gaits. Steel shoes increased landing duration (the time from initial contact to complete hoof stabilization) compared with the barefoot condition and increased the laterality of the initial contact location with a decrease in flat-footed landing. Rolled-toe shoes increased landing duration compared with non-rolled-toe shoes. None of the other modifications significantly affected hoof landing.

—  Hagen J et al. JEVS 2023:104866

Limb Deformities in Foals

Understanding the causes of limb deformities in foals requires population-level studies of many animals followed over time.

Researchers from the United Kingdom (U.K.) conducted this type of study, following a group of Thoroughbred (Tb) foals enrolled from seven farms across the U.K. born over a 2-year period. Data was extracted from mare, farm and veterinary records to investigate mare and pregnancy-related factors associated with limb deformities (angular and flexural deformities) between birth and 6 months of age.

A total of 272 foals from 275 pregnancies (99% live foal rate) among 235 mares were enrolled in the study over two breeding seasons. Fifty-seven (21%) required veterinary intervention for limb deformities during the first 6 months of life. Seventy-five percent of the 57 deformities were flexural and 25% were angular.

After several mare, pregnancy and farm-level factors were considered, only gestation length was found to have a significant association with limb deformities with the risk decreasing as gestation increased between 314 and 381 days (normal gestation length for Tb ranges from 320 to 380 days). No foals born after 360 days of gestation required intervention. The final statistical model predicted the probability of early limb deformities to be 40% at 320 days, 20% at 345 days and 10% at 360 days.    

—  Mouncey R et al. JEVS 2023:104896