The application of a new laminitis scoring method to model the rate and pattern of improvement from equine endocrinopathic laminitis in a clinical setting

Abstract

Background: Endocrinopathic, or hyperinsulinaemia-associated laminitis (HAL) is a common and debilitating equine foot disease, and although no pharmacological treatments are registered, several are under development. To evaluate the effect of such treatments, an accurate and consistent method is needed to track the clinical signs of laminitis over time, and the natural history of the disease, in terms of a 'normal' pattern of improvement, needs to be understood. This study examined the improvement pattern in clinical cases of naturally-occurring HAL subjected to a range of best-practice interventions, using two different scoring methods. Eighty horses and ponies with suspected HAL were enrolled in a study conducted at 16 veterinary practices across Germany. The severity of laminitis was assessed by independent veterinarians using both the traditional Obel method and a modified Obel method developed by Meier and colleagues. Assessments were made on the day of diagnosis (d 0), then on days 4, 9, 14, 25 and 42 during the intervention period. Pain medications were withheld for 24 h prior to clinical examination in all cases.

Results: Time to marked improvement from laminitis varied between individuals, but was difficult to monitor accurately using the Obel method, with the median grade being 2/4 on days 0 and 4, then 0/4 from d 9 onwards. More subtle changes could be identified using the Meier method, however, and the median scores were seen to follow the form of an exponential decay model in most horses, improving from 8/12 on d 0, to 0/12 on d 25. Within this composite scoring method, considerable variation was observed in the rate of improvement of individual clinical signs, with the average time taken for each sign to reach a median score of 0 ranging from 4 days (foot lift and weight shifting) to 25 days (gait when turned in a circle) across all 80 horses.

Conclusions: The Meier method provides a reliable and consistent method for monitoring the clinical status of horses with HAL, and despite the variability, the pattern of improvement described here should provide a useful benchmark against which individual cases and new treatments can be assessed.

Keywords: Diagnosis; Equine metabolic syndrome; Insulin; Laminitis; Obel.

Fig. 1

Median laminitis severity scores determined in 80 horses using the Meier (●) and Obel (Δ) methods over a 42-d period post-diagnosis

Fig. 2

Median laminitis severity scores determined using the Meier (●) and Obel (Δ) methods over a 42-d improvement period, demonstrating an atypical pattern of improvement in four horses (one horse per graph)

Fig. 3

The observed versus predicted scores for the severity of laminitis as measured using the Meier method in 64 horses on 6 occasions during a 42-d improvement period. Predicted values were estimated after fitting an exponential decay model

Fig. 4

Panel a: Median scores for individual clinical signs of laminitis, recorded using the Meier method of severity scoring in 80 horses over a 42-d improvement period. Panel b: Percentage of horses with a positive score for each criterion over the same period (Panel b). The clinical signs included: weight shifting (●), resistance to lifting the forelimbs (Δ), a bounding digital pulse (♦) atypical gait when walking in a straight line (x), atypical gait when turning in a circle (◊)