Incidence and risk factors for recurrence of endocrinopathic laminitis in horses

Abstract

Background: Endocrinopathic laminitis is common in horses and ponies, but the recurrence rate of the disease is poorly defined.

Objectives: To determine the incidence of, and risk factors for, the recurrence of endocrinopathic laminitis.

Animals: Privately owned horses and ponies with acute laminitis (n = 317, of which 276 cases with endocrinopathic laminitis were followed up to study completion).

Methods: This prospective cohort study collected data on veterinary-diagnosed cases of acute laminitis for 2 years. Each case was classified on acceptance to the study as endocrinopathic or non-endocrinopathic using data collected in a questionnaire completed by the animal's veterinarian. Follow-up data were collected at regular intervals to determine whether the laminitis recurred in the 2-year period after diagnosis.

Results: The recurrence rate for endocrinopathic laminitis was 34.1%. The risk of recurrence during the 2-year study period increased with basal, fasted serum insulin concentration (P ≤ .05), with the probability of recurrence increasing markedly as the insulin concentration increased beyond the normal range (0-20 μIU/mL) to over the threshold for normal (up to approximately 45 μIU/mL). Being previously diagnosed with laminitis (before the study; P = .05) was also a risk factor for recurrent laminitis. Cases with a higher Obel grade of laminitis were likely (P = .05) to recur sooner.

Conclusions and clinical importance: Knowing that hyperinsulinemia and being previously diagnosed with laminitis are significant risk factors for recurrence will enable clinicians to proactively address these factors, thereby potentially reducing the risk of recurrence of laminitis.

Keywords: ACTH; equine metabolic syndrome; horse; hyperinsulinemia; insulin dysregulation; pituitary pars intermedia dysfunction.

Figure 1

The probability of recurrence of endocrinopathic laminitis in horses and ponies. A, The relationship between the probability of the recurrence of laminitis and basal (resting) serum insulin concentration (μIU/mL; quantiles) was hyperbolic (P = .05; n = 267). B, The probability of the recurrence of laminitis was lowest in horses/ponies that experienced an initial episode of laminitis in the spring months (data from animals in the Southern hemisphere [n = 242])