Severity and outcome of equine pasture-associated laminitis managed in first opinion practice in the UK

Data from 107 cases of pasture-associated laminitis were obtained from first opinion practices to study factors associated with severity, survival and return to ridden exercise. There were 43 mares and 64 geldings, with a median age of 11 years. Of the 107 animals, 33 were small ponies, 45 were large ponies/cobs, 17 were small horses and 12 were large horses. Ninety-seven animals were categorised as having laminitis as defined by Cripps and Eustace 1999): 76 had mild (Obel grade 1 or 2) laminitis and 31 had severe (Obel grade 3 or 4) laminitis. Forty-three animals had previously had laminitis, and were significantly less likely (P=0.02) to have severe laminitis than those that had not. Eighty-nine animals were overweight, and there was a trend (P=0.09) towards severe laminitis cases having a higher body mass index. Eight weeks after disease onset, 102 animals were alive. Lower bodyweight, optimal body condition, mild laminitis and category of acute/chronic founder as defined by Cripps and Eustace (1999) were significantly associated with survival. There was a trend (P=0.06) towards treatment with acepromazine being associated with survival. Of the 81 animals that were used for riding, 48 were being ridden again; this was 2.6 times more likely in animals without previous laminitis. The clinical outcome was judged by a panel of three veterinarians as ‘good’ in 77 of 107 of cases. Clinical outcome was significantly associated (P=0.03) with horse type: the outcome was ‘bad’ in none of the small horses, compared with 15 of 45 large ponies/cobs, 11 of 33 small ponies and three of 12 large horses.