Lack of attentiveness in horses linked by researchers to back pain

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Attention or monitoring behaviour in horses is characterized by standing motionless at the stall door, with their neck horizontal or slightly elevated, ears and neck mobile, and slowly scanning their environment by moving their head laterally or occasionally gazing for a short moment at environmental stimuli.
Attention or monitoring behaviour in horses is characterized by standing motionless at the stall door, with their neck horizontal or slightly elevated, ears and neck mobile, and slowly scanning their environment by moving their head laterally or occasionally gazing for a short moment at environmental stimuli.

Do you have trouble with an inattentive or disengaged horse? It could be that the animal is suffering from back problems, research suggests.

Horses’ inattentiveness to their day-to-day environment has been linked to back pain in a French study.

The study team found a correlation between what they described as lower attentional engagement and the level of back problems in the horses.

The researchers from the University of Rennes 1, writing in the journal Scientific Reports, said their results yielded interesting indications for evaluating animal welfare.

“Attentional engagement could become a reliable indicator of chronic pain and thus a useful tool for identification of suffering individuals,” Céline Rochais and her colleagues suggested.

The researchers said scientific literature repeatedly reported attention deficits and other cognitive impairments in human patients with chronic lower back pain, fibromyalgia, migraine, rheumatoid arthritis, and musculoskeletal discomfort.

“Pain is an inherently attention-demanding sensory process and distraction of attention has been shown to reduce perception of acute pain,” they said.

Animal-related studies in the area were scare, they noted, and were often based around the level of physical activity and appetite, which can both decrease as a result of pain.

The researchers set out to evaluate domestic horses’ attentional engagement in their home setting and compare it to estimates of vertebral disorders assumed to be linked to chronic pain.

The research comprised two studies – the first involving 59 riding-stable horses from three facilities and the second involving 44 horses from five facilities.

In the first study, the horses’ spines were assessed beforehand by a specialist practitioner while in the second study they were assessed using static surface electromyography (sEMG), a technique considered highly reliable to evaluate human patients’ lower back pain.

A total of 90 instantaneous scans of each horse were recorded by an experienced observer across three sessions during calm moments in their stables. The observer was looking for evidence of attentiveness or monitoring behaviour at their stall door – the likes of standing with their neck horizontal or slightly elevated, ears and neck mobile, and scanning their environment by moving their head laterally or occasionally gazing for a short moment at environmental stimuli.

In the first study, no evidence of back issues was found in just 15 percent of the horses. They ranged up to horses in which 88% of the vetebral sites examined were believed to be affected by problems.

They found in subsequent data analysis that the more the horses monitored their environment, the less affected they were by back issues.

“In other words, healthy horses were more attentive to their environment,” they reported.

Horses deemed unaffected or only slightly-affected (with one vertebral site affected) monitored their environment significantly more than severely affected animals – those assessed as having two or more vertebral sites affected.

In the second study, the sEMG evaluations indicated that 61% of the horses showed high muscular activity at one vertebral site or more.

The overall results were largely similar to those of the first study.

“Correlation between cervical spine area evaluations and monitoring was still stronger, suggesting that neck problems may impact more attentional engagement,” the study team wrote.

They noted that the prevalence of back disorders was assessed as higher in the first study.

“This could be due to management differences. Nevertheless, pooled data for the two studies revealed a still stronger negative relationship between times horses spent monitoring and the numbers of vertebral sites affected. This correlation was confirmed when only the cervical area was considered.”

Discussing their findings, the study team said the findings clearly linked lower attentional engagement with the level of back disorders.

“This is especially clear as two different evaluation techniques used to evaluate the state of the spines gave similar results. One study showed that data for the neck area in particular contributed to this correlation.”

They acknowledged that the evaluations of the horses may not be indicative of chronic pain, as they did not measure it directly.

“Although animals’ chronic back pain, unless intense enough to induce immobility or lameness, is difficult to detect, all practitioners consider that elevated tenseness at vertebral sites reflects chronic pain.”

They noted that horses’ chronic back pain is known to be correlated with aggressiveness towards humans.

“Our demonstration showing that an animal spontaneous attention to the environment can be impaired by chronic back pain opens new lines of research for humans,” they said.

“It suggests that novel animal models could prove useful for preclinical research on chronic pain-related cognitive impairments.

“Our results are of great interest for evaluations of animal welfare and suggest that this approach should be developed for other domestic or captive species. If attentional engagement (or sensory inattention) proves a reliable indicator of chronic pain or discomfort for a variety of species, it would be a useful tool for a rapid and economical identification of potentially suffering individuals, leading to appropriate treatments or remediation.”

They noted that depressed-like animals and anaemic horses tended to isolate themselves from environmental stimuli, suggesting that, like human patients suffering from chronic pain, they lived in what other researchers have described as an impoverished and restricted environment.

“Chronic pain, being inescapable, is often associated with depression also in humans. Animal models should help disentangle the processes involved. The finding that the neck area of the spine is particularly involved in cognitive impairments related to both horses’ and humans’chronic pain deepens the parallels.”

Rochais, C. et al. Lower attention to daily environment: a novel cue for detecting chronic horses’ back pain? Sci. Rep. 6, 20117; doi: 10.1038/srep20117 (2016).
The full study, published under a Creative Commons License, can be read here

 

 

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