Prevalence and risk factors for laminitis within the Norwegian pony breed Nordlandshest/Lyngshest

Laminitis is a systemic condition resulting in debilitating pain and structural changes within the feet, and hence has major welfare implications. Causes include endocrine and systemic inflammatory conditions. Ponies are frequently affected, and observations in the field suggest that occurrence of laminitis is also common in Norwegian breeds. The aim of this study was to estimate the prevalence and risk factors for laminitis within the Norwegian pony breed Nordlandshest/Lyngshest.

The study was a cross-sectional study based on questionnaires sent to members of the Norwegian Nordlandshest/Lyngshest breed association. Questionnaires were received for 504 animals, of which 464 records were eligible and included in analyses. The population comprised 71 stallions, 156 geldings, and 237 mares, with an age between 1 and 40 years (median and interquartile ranges: 12 (6-18) years). The estimated 3-year period prevalence of laminitis was 8.4% (95% confidence interval (CI₉₅): 6.0-11.3%), whereas lifetime prevalence was 12.5% (CI₉₅: 9.6-15.9%). Mares had a significantly higher period- and lifetime prevalence of laminitis than male horses, and horses 10 years and older had a significantly higher prevalence than younger horses. The lifetime prevalence of laminitis was 3.2% in horses 9 years and younger, whereas from 17.3-20.5% in older horses. Multivariable logistic regression analysis identified age, sex, and regional adiposity as significantly (P < 0.05) associated with the 3-year period outcome of laminitis: Horses older than 9 years had a three-fold increase in the likelihood of having laminitis compared to the younger horses (Odds Ratio (OR)_10-14 years = 3.37 (CI₉₅ = 1.19-9.50), OR_15-19 years = 3.06 (CI₉₅ = 1.04-9.05), and OR_>20 years = 2.70 (CI₉₅ = 0.90-8.02). Mares were more than twice as likely (OR = 2.44 (CI₉₅ = 1.17-5.12) to have laminitis compared to male horses, and horses with regional adiposity had increased odds (OR = 2.35 (CI₉₅ = 1.15-4.82) of laminitis compared to horses without regional adiposity.

Laminitis appears to be a considerable welfare issue in the Norwegian pony breed Nordlandshest/Lyngshest. The identified risk factors age, sex, and regional adiposity highlight the need for improved owner education and awareness of strategies to reduce laminitis risk.