Risk factors for strangulating lipoma obstruction and lipomata in horses.

Background: Strangulating lipoma obstruction (SLO) is the most common cause of equine small intestinal strangulation and is fatal without surgery. Currently, epidemiological information is primarily limited to signalment-related risk factors and requires further investigation.

Objectives: To identify horse-level risk factors for SLO and/or abdominal lipoma(s) (LP) formation in horses with acute colic that underwent surgery or post-mortem examination at participating equine clinics.

Study design: Prospective, international, multicentre, epidemiological study.

Methods: An epidemiological study was conducted over 27 months (January 2022-April 2024) in 8 clinics (UK n = 4, USA n = 4) to identify variables associated with altered likelihood of SLO and/or LP. Horses presenting with acute colic signs that underwent surgery or post-mortem examination were eligible. Those (i) that had SLO as the primary cause of colic, or (ii) those that had mesenteric and/or omental lipoma(ta) (LP) were compared to horses without lipomata. Signalment, adiposity, endocrine status, and lipomata deposition data were analysed using univariable and multivariable logistic regression models.

Results: Data from 392 horses was obtained (108 SLO; 190 LP). Increasing age (odds ratio [OR] 1.23) for every year increase in age 95% CI (95% CI: 1.17-1.30, p < 0.001), male sex (OR 1.78, 95% CI: 1.08-2.95, p = 0.02) and clinical indicators of Equine Metabolic Syndrome (EMS) (OR 4.77, 95% CI: 2.93-7.77, p < 0.001) were significantly associated with increased likelihood of SLO. Increasing age, clinical indicators of EMS, indicators of previous/current laminitis (hoof growth ring score), jejunal mesenteric fat score and omental fat scores were significantly associated with increased likelihood of LP.

Main limitations: Population restricted to horses with acute colic signs admitted to collaborating clinics.

Conclusions: Measures to prevent adiposity and EMS development appear important to reduce the likelihood of LP and SLO. Further investigation of differential adipose tissue deposition between male and female horses is warranted.