What and Why are Ulcers in the Horse
An ulcer is a sore in the lining of the stomach wall. The horse’s stomach is divided into two areas: One third is the Oesophageal or Squamous part and is nonglandular – so no secretions. Two thirds is the Glandular (lower) region and does secrete a mix of hydrochloric acid, pepsin, bicarbonate and mucous and has a protective mucus layer. Science had determined that ulcers should be called Equine Gastric Ulcer Syndrome or EGUS as ulcers in themselves are not a disease and have many causes and symptoms. This definition was pertaining to ulcers in the squamous region. However just to complicate things further they have now found that ulcers develop in both areas of the stomach and those in the Glandular region should be referred to as Equine Glandular Gastric Disease EGGD. So, two areas of the stomach capable of producing ulcers from different causes. The Squamous region is the most common site of ulcers, and a common cause here is due to a lack of fibrous (slow moving) feedstuff. This part of the stomach is affected by the acid from the glandular region 24 hours a day, every day. It does not secrete the balancing factors like mucous and bicarbonate and does not have a good protective lining. When insufficient forage is available to the horse, the free-flowing acid is not neutralised by the food and damages the wall of the stomach. Ulcers are often diagnosed in racehorses due to lower fibre and high carbohydrate diets which pass quickly through the stomach. Stress can create ulcers. It is true that a stressed (from performance demands, travel, new environments, pain) horse may not eat well, and this can be an ulcer trigger. In the Glandular region, ulcers develop because of a disruption of the balance of the acids and the antacids and also the disruption of the structure of the wall of the stomach by medications such as Bute, NSAIDS and other drugs. They alter the cellular formation, particularly affecting the Phospholipids which are a core of the protective mucous. The key to a healthy stomach free of ulcers is the maintenance of the protective quality of the mucous lining.
What are the Signs and Symptoms of Equine Ulcers
Not all ulcers will show clear symptoms, and tests have shown that horses can have ulcers without any outward signs. When ulcers cause pain, then horses will show signs of pain. Their behaviour may alter from being touchy and defensive to being angry and aggressive. There have been studies to show the effect of feeding soya fats on improving the behaviour of horses, – it follows that behaviour improves with removal of pain. Signs vary due to the level of pain but also the natural temperament of the horse. A horse may be touchy and a change in temperament, grind its teeth, start wind sucking and it may have weight loss. A competition or racing horse can have reduced performance. Unfortunately, these outward signs can be caused by other sources of pain, so the most direct way is to ask your veterinarian to perform an endoscopy examination. They will pass a tube down the throat and into the stomach. This tube has a camera and ulcers can be seen. There are grades of ulcers, and the vet can advise the seriousness of any ulcers detected, sometimes low-grade ulcers are found but they are not the source of the pain symptoms.
Ulcers in Foals
Foals can have ulcers and they cause serious issues, even death. Foals secrete gastric acid at 2 days old and the acidity is high. The cause is from the lack of food intake (mares’ milk) from possibly an intolerant mare, a weak or sick foal not making the effort to feed, resting too much or exterior interruptions to feeding. As above this is an ulcer of the squamous region. It can also be the imbalance between the acidic factors and the antacid factors that can cause this ulceration, in the glandular region. A foal may show signs of only intermittently drawing milk, colic, poor condition, diarrhoea. A veterinarian should be called if these signs are noted.
How can Ulcers be Healed
Antacids are the first response to an ulcer. Treatment from a veterinarian is necessary and they will offer a product containing Omeprazole. This is a Proton Pump inhibitor – an acid blocker (like Losec or Zantac for humans) and is given daily for 28 days.
Omeprazole blocks the production of acid and will allow healing to take place; the usual course length is 28 days. It is not a suitable long-term intervention to prevent ulcers, as it reduces the uptake of calcium, so a mineral mix, with correct calcium levels, of 20g per day and lucerne chaff can offset the reduction to some degree. Feeding calcium alone is not recommended as it will alter the important ratios of minerals. Alternatively feeding lucerne chaff and a dose of minerals once a day will suffice.
There is also the Rebound Effect when the course of Omeprazole is ended. The reaction from the physiology of the horse is to immediately increase the acid flow to a much higher level for a few days. This can trigger the start of a new ulcer.
How can Ulcers be Prevented
The immediate prevention can be achieved by feeding an acid neutraliser supplement, especially for all the times a stomach may not have feed inside, e.g. stabling with insufficient hay, travelling, trying to diet an overweight horse or pony. Vetpro Acid Protect supplement is scenically proven to neutralise acid for 6 hours per dose. When a horse is due to do a strenuous workout, a race or competition, it is usual not to give a feed to avoid colic. However, this is the time acid splash occurs from the movement of the horse and acid moves up to the squamous area causing discomfort that can negatively affect performance as well as trigger an ulcer. A handful of chaff with Acid Protect can help prevent acid splash.
Look at the feeding programme and make sure the horse has access to forage (fibre such as grass, hay, chaff etc) 24 hours a day. If a horse is being stabled or penned, then he should have access to hay for that time. (Note hay should be washed). Keep the intake of Bute or other pain reducing drugs to a minimum if possible. Provide an acid neutraliser for the times that a horse does not have grass or forage (e.g. chaff) in the stomach, and times of medication.
The current myth of “grass affected” horses from mycotoxins in grass (Check out the article on our website – www.vetpro.co.nz/toxins-and-binders/) is being made a reason to withdraw horses from naturally grazing on pasture and that will have a direct effect on the likelihood of ulcers forming. Horses that seem over excited from the grass just need a supplement such as Digest-Rite Sport + to asst the digestion of the fructans and that behaviour will disappear. It can create stress in a horse to lock him up away from other horses and unable to roam and graze naturally. Hay is often substituted but as it is dried grass it makes no sense to replace pasture with hay. Often hay is not available continuously to the horse as pasture would be. Allow the horse access to pasture and feed a supplement to assist digestion of pasture, check out Vetpro Digest-Rite on our website www.vetpro.co.nz/product/digest-rite-sport-2/. Calcium is found naturally in legumes such as lucerne and clover. Feeding lucerne chaff and a good formula mineral supplement will provide all the calcium needed. Overfeeding calcium is negative to a horse’s health, so check out the total intake from all feed intake and keep to a daily level of 20 gm for maintenance an average size horse, 40 gm if in hard work.
Where practical reduce grains and cereals and increase fat in the diet, e.g. soya bean oil, rice bran. Avoid overuse of pain-relieving drugs. Take time to introduce ahorse to new environments and reduce stress with careful handling.
References
L. Holland2, D. S. Kronfeld, and T. N. Meacham Feeding alfalfa hay to exercising horses reduces the severity of gastric squamous mucosal ulceration.: Lybbert, T.; Gibbs, P.; Cohen, N.; Scott, B.; Sigler, D. 2007
Evaluation of diet as a cause of gastric ulcers in horses J A Nadeau 1, F M Andrews, A G Mathew, R A Argenzio, J T Blackford, M Sohtell, A M Saxton 2000 Nutritional Management of Gastric Ulceration Andrews et Al 2017
Leleu, C., & Couroucé, A. (2023). Studies Effect of a blend of magnesium oxide on equine squamous gastric disease in young trotter horses under training. Journal of Veterinary Science, 24(6), e118. https://doi.org/10.4142/jvs.23118 (2)
Veterinary School of Nantes, Inovalys Laboratory (2021) In-Vitro evaluation of gastric pH and kinetics in horses. Lester, G. D., Smith, R. L., & Robertson, I. D. (2005).
Effects of treatment with omeprazole or ranitidine on gastric squamous ulceration in racing Thoroughbreds. Journal of the American Veterinary Medical Association, 227(10), 1636–1639. https://doi.org/10.2460/javma.2005.227.1636
Lorenzo-Figueras, M., & Merritt, A. M. (2002). Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses. American Journal of Veterinary Research, 63(11), 1481–1487. https://doi.org/10.2460/ajvr.2002.63.1481 Pagan, J. D., Petroski-Rose, L., Mann, A., & Hauss, A. (2020).
Omeprazole reduces calcium digestibility in Thoroughbred horses. Journal of Equine Veterinary Science, 86, Article 102851. https://doi.org/10.1016/j.jevs.2019.102851
Shan, R., Steel, C. M., & Sykes, B. (2023). The impact of two recommended withholding periods for omeprazole and the use of a nutraceutical supplement on recurrence of equine gastric ulcer syndrome in Thoroughbred racehorses. Animals, 13(11), Article 1823. https://doi.org/10.3390/ani13111823
Sykes, B. W. (2021). A free ride: Is long-term omeprazole therapy safe and effective? Equine Veterinary Education, 33(10), 556–560. https://doi.org/101111/eve.13458 Vokes, J., Lovett, A., & Sykes, B. (2023). Equine gastric ulcer syndrome: An update on current knowledge. Animals, 13(7), Article 1261. https://doi.org/10.3390/ani13071261
