Laminitis is a painful and common condition that can be caused by hyperinsulinaemia (also known as endocrinopathic laminitis), mechanical, or inflammatory factors. Ponies are at a higher risk of hyperinsulinaemia-associated laminitis than horses, but further research is required to quantify how different risk factors may combine for this disease.  

Researchers in the U.K. aimed to identify the most useful physical examination, metabolic, and management factors to predict laminitis risk in nonlaminitic ponies. The study included 374 ponies (aged 5-32 years) and 891 pony-years. The researchers visited each pony every six months for up to four years to monitor them for the development of laminitis. 

At each visit, the ponies underwent a standardized veterinary examination. The researchers collected data in three categories:  

  1. Blood analytes: The researchers analyzed the ponies’ basal blood samples for serum insulin concentrations and plasma concentrations of adiponectin, triglycerides, glucose, and adrenocorticotrophic hormone (ACTH). They also analyzed blood samples taken 30 and 60 minutes after a modified oral sugar test (OST) for insulin only. 
  1. Physical/clinical measurements: The researchers recorded the ponies’ weight, height, body length, neck length, heart girth, belly girth, body condition score, cresty neck score, and the presence or absence of hypertrichosis, bulging supraorbital fat pads, a pot belly, or forelimb evidence of divergent hoof growth.  
  1. Owner/keeper questionnaire: At each visit, owners/caretakers completed a questionnaire documenting the ponies’ diet, management, and health. 

The laminitis incidence in this study was 4.8 cases/100 pony-years. Laminitis development was significantly associated with basal insulin concentrations, insulin 60 minutes after an OST, adiponectin, and divergent hoof growth. ACTH (often measured for diagnosing pituitary pars intermedia dysfunction) was not independently associated with laminitis.  

The researchers concluded that basal insulin concentrations and insulin measured 60 minutes after administration of corn syrup best quantify the risk of future laminitis development in nonlaminitic ponies. They noted that these insulin values “may be used to classify ponies as high-, medium-, or low-laminitis risk such that preventative strategies can be targeted on those at highest risk.” 

Reference 

Knowles EJ,  Elliott J,  Harris PA,  Chang Y-M,  Menzies-Gow NJ.  Predictors of laminitis development in a cohort of nonlaminitic ponies. Equine Vet J.  2023; 55(1): 12–23. https://doi.org/10.1111/evj.13572 

Further Reading

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