Insulin Risks in Australian Ponies

Abnormal insulin metabolism, called insulin dysregulation (ID), is an important component of equine metabolic syndrome, a common endocrine cause of laminitis in horses and ponies. Researchers from Australia conducted a cross-sectional survey of Shetland and Welsh ponies to estimate the prevalence of ID and identify risk factors for the disease.

Testing for high insulin levels, called hyperinsulinemia, and insulin resistance, where the body doesn’t respond normally to insulin, was conducted on 167 pony stallions, geldings and non-reproductive mares. The general health, height, weight, cresty neck score, body condition and signs of laminitis, if any, were also recorded.

The median age of the ponies was 9 years with a median body condition score of 5 (on a 1-9 scale according to owners) and 6 (moderately fleshy on a similar 1-9 scale according to veterinarians).

Test results for more than half (61%) of the ponies indicated they had ID. Increasing age, being female and higher body condition as assessed by the owners were identified as risk factors for ID. Almost 1/3 of the ponies (28%) showed signs of laminitis. The risk factors identified for laminitis included ID, insulin resistance and equine Cushing’s disease (pituitary pars intermedia dysfunction which affected 7% of the ponies). This study highlights the increased risk of ID and laminitis in these pony breeds compared with what is expected among horses, suggesting that increased monitoring of endocrine function would benefit their management.

— Clark BL et al. EVJ 2024;56:281-290

Return to Performance Following Suspensory Injury

Veterinarians working with the Hong Kong Jockey Club compared the prognosis for returning to athletic performance following injuries to the palmaroproximal aspect of the third metacarpus (the area behind the knee at the top of MC3, the front cannon bone). Injuries in this area primarily involve proximal suspensory ligament desmitis (SLD) but also include reactive bony changes as well as avulsion, stress and cortical fractures of the MC3 in this area.

This retrospective study used the medical records of 29 horses examined for forelimb lameness later confirmed to originate from the area around the proximal suspensory ligament using magnetic resonance imaging (MRI) from 2014 to 2022.

All horses examined were male, and the median age was 4 years. About half had raced in Hong Kong before injury with a median of 3½ starts each. Left and right limbs were equally represented with one horse affected bilaterally. Most of the horses (62%) were Grade 2 lame (Scale 0-5) with the remainder (31%) Grade 1 or (7%) Grade 3. Diagnostic nerve blocks confirmed the area as the source of lameness in 86% of the cases. MRI revealed that 35% of the horses had SLD involvement only, 48% had desmitis along with avulsion or fissure fractures and 17% had an area of reactive bone or a fissure fracture only.

Treatment included rehabilitation exercise, anti-inflammatories and shock wave therapy for most (75%) horses. Overall, 92% of horses returned to galloping, while 67% returned to racing. Reinjury occurred in 18% of the horses. Horses with bony involvement in addition to SLD took longer to return to galloping (116 days) compared with those with SLD only (69 days).

— Ratcliffe TOC et al. JAVMA 2024;262:383-390

Measuring the Hooves of Egyptian Arabs in Qatar

An international collaboration of researchers conducted a small study of 10 Straight Egyptian Arabian horses documenting the size and shape of the breed’s hooves using radiographic measurements with an eye toward better management of laminitis should it occur.

Normal adult mares from 3-18 years of age with no history of laminitis were used in the study. A total of 23 measurements were taken from dorsopalmar/plantar, mediolateral and dorsal 45-degree proximo-palmarodistal oblique views of each front and hind hoof.

Dorsal hoof wall angle, which was not significantly different between front and hind feet, averaged 48 degrees; and heel angles were 47 degrees and 53 degrees for the front and hind, respectively. Sole depth averaged about 1.5 cm, divergence of the toe angle and P3 angles was 0.08 degrees and the so-called Peloso ratio (ratio of hoof wall thickness at the tip of P3 : palmarocortical length of P3 as a percentage) was 29.5%.

Although it is difficult to know how representative this small sample may be to the overall breed characteristics of the Straight Egyptian Arab, it could provide the start of valuable baseline data for the breed.

— Jacquinet G et al. JEVS 2024:105072

Salt Preferences of Mares Eating Grass Hay

Researchers at Cornell University surveyed 342 horse owners to determine what types of salt they most often provided to their horses.

Plain, mineralized or Himalayan salt were equally common (each about 30% of respondents). After adding a selenium block to these types of salt, the investigators conducted a preference study with groups of eight to 12 mares. Each group was offered a choice between the types of salt and fresh salt blocks vs. previously licked blocks.

There was considerable variation in how often horses visited the salt blocks, from one to 42 visits each with no preference between new and used salt blocks. There were few preferences between the types of salt. Plain and mineralized blocks were equally popular. There was a modest preference for mineralized blocks vs. those with added selenium. There also was a significant preference for plain salt over Himalayan salt.

Although there was no effort to estimate how much salt the horses were consuming, the authors concluded that mineralized or selenium blocks can provide the sodium chloride horses need, in addition to other minerals.

— Sill S et al. ResVetSci 2024:105224