Effect of hay nets on subluxations, pain-pressure thresholds, and cervical range of motion in the axial skeleton of adult horses.

The research studied if using hay nets for feeding horses affects their skeletal health, specifically focusing on subluxations or partial dislocation of joints, pain threshold, and neck movement range. They found that horses fed with hay nets had slightly more subluxations and increased neck flexibility, but there was no difference in pain threshold.

Research Objectives and Methodology

• This research aimed to assess any potential impact on the skeletal health of horses due to the use of hay nets, a feeding device designed to slow down consumption and reduce hay waste.
• The specific aspects of skeletal health that the study examined were subluxations (partial dislocations), the range of motion in the neck, and pain-pressure thresholds, collectively referred to as the measurements of the axial skeleton (the part of the skeleton that consists of the skull, the vertebral column, and the rib cage).
• A total of 13 horses were involved in the experiment, which spanned two years from September 2021 to September 2023. During this time, they were randomly assigned to one of two groups: one fed using hay nets (NET) and the other fed without nets (CON).
• The horses’ subluxations were measured by a chiropractor twice a year. The range of motion in the neck and the horses’ sensitivity to mechanical pressure (mechanical nociceptive thresholds) on key parts of the body (jaw, poll, and withers) were evaluated three times a year.

Research Findings

• The results showed that the horses fed using hay nets had an average increase of 1.6 points in cervical subluxations compared to horses not fed with hay nets. This indicates a slight increase in partial joint dislocation in horses fed using hay nets. However, no changes were observed in the temporomandibular joint (TMJ) or the thoracic (mid-back) or lumbar (lower back) vertebral regions.
• The study also found that the neck movement range was slightly higher (5 degrees more) in horses fed using hay nets when measuring movement from chin to chest and chin to fetlock (the area just above a horse’s hoof).
• Moreover, there was no difference in the horses’ mechanical nociceptive thresholds (an indicator of pain sensitivity), regardless of whether they were fed using hay nets or not.
• Overall, the study concluded that using netted round bales for feeding horses may have minor impacts on their axial skeleton but these observations were over a short duration of 12 weeks.