Since the advent of gastroscopy – passing a long telescope-like instrument into a horse’s stomach in order to assess the stomach lining – we have become aware of the high frequency of occurrence of gastric ulcers in horses from all sorts of work disciplines. These ulcers tend to occur in specific locations but vary in their size and depth. The big questions that arise are what is their underlying cause and what influence do they have on performance?
It has been my observation over many years of talking to horse owners that if a horse is performing below expectations, then often gastroscopy is performed, and if ulcers are identified expensive treatment follows. However, it is also clear that although the ulcers may improve, there is not always an associated improvement in the horse’s behaviour.
So what scientific evidence is there that gastric ulceration causes a decrease in ridden horse work quality? There is a single case report which described four Thoroughbred racehorses that presented with poor performance and gastric ulceration as the only abnormal finding, and improved performance after treatment with omeprazole was observed. In a case series of 37 horses with girth aversion behaviour, one-third of horses had gastric ulcers and owner-reported behaviour improved after treatment with omeprazole. In a large group of Thoroughbred racehorses an association between the presence of gastric ulcers and poor performance was identified, but no other investigations were performed to determine if there were other potential causes. An association does not equate with a causal relationship.
A group of international experts in equine internal medicine produced a consensus statement in 2015, concluding ‘that a wide range of clinical signs might be present in individual cases of equine gastric ulcer syndrome (EGUS), with varying degrees of reduced appetite and poor body condition the most prevalent at a population level. Although inconsistent, effects on behaviour are not uncommon. Likewise, it is recognised that EGUS might result in poor performance; however, given the numerous factors that potentially contribute to poor performance other causes need to be considered.’
One of the lead authors, Dr Ben Sykes, has subsequently stated in 2021 that 50% of the horses presented to him with suspected gastric ulceration are lame horses, and the cause of lameness needs to be identified and managed appropriately in order to improve performance. This certainly mirrors my experience. A large proportion of sports horses that I have assessed in the last 10 years because of either a failure to perform to expectations or a decline in performance have already undergone gastroscopy and treatment for EGUS, but the majority have failed to show any improvement in performance. All of these horses have had one or several sources of musculoskeletal pain and when nerve blocks have been performed to remove pain there has been an immediate improvement in lameness, work quality and ridden horse behaviour. I strongly suggest that these horses are under chronic stress because of on-going musculoskeletal discomfort and this stress predisposes to the development of EGUS.
So, my take home message is that by far the most common cause of poor performance is musculoskeletal pain. This may not be manifest as overt lameness, but careful assessment of the horse’s movement when ridden in all gaits, together with tack fit for horse and rider, will usually reveal that the horse’s movement is compromised. The next challenges are to identify and manage the primary causes!
© Sue Palmer, The Horse Physio, 2021
Treating your horse with care, connection, curiosity and compassion