Risk factors associated with owner-reported sleep disturbances in Nordic horses.

Background: Very little is known about sleep disturbances in horses, although several management or animal-based factors may contribute to an increased risk of disturbances.

Objectives: To investigate factors related to rest and sleep behaviour of horses kept in stalls as perceived by Nordic horse owners or caretakers and their association with suspected sleep disturbances (SSD).

Study design: Cross-sectional survey.

Methods: The 40 question online international survey included a convenience sample of horse owners or caretakers with horses over 4 years old kept in the same individual stalls for at least the last three previous months. Multivariate binary logistic regression was used to generate models of the factors associated with the SSD and their possible causes and consequences for the horses.

Results: Overall, 5.0% of respondents (88/1749) suspected that their horse had sleep disturbances. The horse-specific factors which were associated with SSD (adjusted OR; 95% CL) were age in years (1.12; 1.07-1.16), withers height (1.05; 1.03-1.08), current illness/injury (3.14; 1.92-5.15), if the horse was not seen laying down (27.82; 8.72-88.75), nightly injuries (9.16; 3.36-25.00), loss of balance/unexpected fall (40.30; 16.77-96.87), daytime drowsiness (3.85; 1.68-8.82) and difficulties lying down/getting up (16.33; 6.02-44.30). The environment-specific factors associated with SSD were hard and dry (3.50; 1.56-7.84) and hard and wet (8.63; 2.41-30.94) lying surface.

Main limitations: Self-selection enrolment of participants may limit the generalisability of the findings.

Conclusions: Several environmental and horse-related factors were found to be associated with SSD in horses, including hard and dry/wet lying surfaces.