GASTRIC ULCERATION Dr C.J. (Kate) Savage BVSc(Hons), MS, PhD, Diplomate ACVIM Specialist in Equine Internal Medicine Head, Clinical Services, Equine Centre, University of Melbourne, Werribee 3030, VIC, AUSTRALIA Summary: Ulcers can be of great importance to foals, performance horses, horses with chronic orthopaedic problems and to other horses with illness requiring medication with non-steroidal pain relief. Gastroscopy is so important in performance horses because it allows us to visualise the stomach [saccus cecus, cardia (around the oesophagus), non-glandular (squamous) mucosa circumferentially above the margo plicatus (i.e. the margin of squamous meeting glandular mucosae), glandular mucosa including glandular fundus and pylorus]. We can then go into the duodenum on most horses. Then as we retract the gastroscope the oesophagus is examined thoroughly, as ulceration is sometimes seen in the distal 10-20 cm (usually if the cardia is affected with moderately severe ulceration). TERMINOLOGY to explain to your clients: Endoscopy This is the proper term for scoping, which is when vets insert a tube ( scope ) into the nasal passage of the horse or insert the scope into the urethra, vagina or even rectum of the horse. The scope can be connected to a TV in the newer models or vets can look through a small eyepiece to see the picture of internal structures. This is a marvellous diagnostic tool. Oesophagoscopy = scoping the tube that runs from the throat to the stomach (the oesophagus) This is the term for when the scope is introduced through the nasal passage and into the throat (nasopharynx) and then down into the oesophagus. This is useful if horses have choke (oesophageal obstruction) or after a choke. It is also useful if there are ulcers in the oesophagus (which is not as common as in humans). Gastroscopy This means endoscopy of the stomach. It requires a very long endoscope for an adult horse a minimum of 2 metres (but that will rarely reach the bottom of the pylorus) and more frequently a 3 metre endoscope. Gastroduodenoscopy This is the term for scoping the stomach and the duodenum.
Figure 1: A custom made 3 metre endoscope. This is a great way to store it once it has been cleaned and disinfected. ANATOMY Mucosa The lining of the stomach and bowel Non-glandular mucosa This is the light pink lining sometimes described as the colour of uncooked chicken breast. This is a common area to be affected by: 1) hyperkeratosis - thickening of the lining often a sign that the stomach has been attempting to heal; 2) erosions and 3) ulceration. This is also the area that has gastric (stomach) contents pushed up onto it when the horse gallops. Glandular mucosa This is the pink lining below the margo plicatus. If this is ulcerated it is often more serious and can cause quite severe colic signs. It is more common in foals than in adults, but can still occur in adults including in the pyloric region (pylorus).
Figure 2A and B: A) Left: Normal stomach the light pink lining (mucosa) is the nonglandular lining and the darker pink lining is the glandular lining (mucosa). The line of demarcation is called the margo plicatus. B) Ulcerated and hyperkeratotic (thickened yellow) lining of the stomach Margo plicatus This is the line of demarcation between the non-glandular (or squamous) lining of the stomach and the glandular portion. Cardia This is the area of the stomach near where the oesophagus enters. Pylorus This is the end of the stomach, where it enters into the small intestine (the duodenum). Ulcers and erosions are more common here than many vets think because the pylorus does not always get examined. The horse needs to be held off feed and water well to examine this area. Duodenum This is the first part of the bowel. The duodenum is the initial part of the small intestine. It is more commonly affected with ulceration in foals than in adults. Sometimes we take biopsies of the lining from the duodenum, but an endoscopic biopsy is small and very superficial (not deep). Figure 3: An endoscopic picture of the duodenum. You can see bile spurting out from the bile duct into the duodenum. The duodenal lining (mucosa) appears normal. Gastroscopy is used in horses commonly
Gastroscopy/Duodenoscopy/Oesophagoscopy can be done easily as an out-patient procedure. However, some clients like the horse to arrive at the clinic the day before so the horse can be held off feed there. Before this procedure is performed the horse must have been held off feed and then water in order to examine the stomach in an empty state. This allows us to see the lining of the stomach. If it is really hot weather, we may delay the removal of water. Typically a horse that is scheduled to have a 10 am Monday morning stomach scope needs to be held off feed from approximately 3 or 4 pm on Sunday and water removed at approximately midnight or if hot, we might allow 6 litres of water in until 6am. Individual hospital requests will be explained to you at the time of booking in the horse. We usually go down to the stomach rather quickly with the long (2.5-3 metre) endoscope and then look at the oesophagus last. We do this when we have retracted the endoscope back out of the stomach after the examination of the stomach and duodenum. We usually look for ulcers and erosions in the last 10-20 cm (distal oesophagus) of the oesophagus, just before it connects to the stomach. Vets performing the gastroscopy may be especially interested in the oesophagus if there are signs of ulceration in the cardia of the stomach. Ulceration and involvement of the oesophagus is more common in people than in horses, but it still occurs in horses. The most common reason for wanting to scope the oesophagus is during or after a choke episode (oesophageal obstruction - usually with food). Sometimes the oesophagus must be examined to see if we need to arrange special feeding/fluid administration plans or medication for the horse. The stomach is divided into two different lining (mucosa) types: 1) non-glandular (squamous) mucosa - light pink in colour 2) glandular mucosa (including glandular fundus and pylorus) darker pink in colour We also examine the margin between the non-glandular and glandular linings, because this often is involved in ulceration, erosion and thickening of the lining cells as they try to heal (hyperkeratosis). This margin between the two different types of lining is called the MARGO PLICATUS and is very obvious because of the colour demarcation. It is always a good place to look at as squamous ulceration often occurs just above this line. It s also quite exciting because when we are in the stomach, we turn the scope (endoscope) so that we can see the entrance of the oesophagus to the stomach. This means that we can see part of our scope entering the stomach too. This is called the CARDIA and if there is ulceration here, we should ensure that when we are finished with the duodenum and stomach that we come out of the stomach into the oesophagus slowly, and examine the lining for about 20 cm, as we pull out. After examining the upper stomach we dive into the fluid (even though horses have been held off feed from approximately 3-4 pm the day before the appointment and had water restricted over night and then removed at approximately 6 am depending on weather conditions!!). Through the fluid we examine more of the glandular mucosa and then the scope is pushed into the pylorus. The pyloric region has the exit hole from
the stomach into the bowel (the duodenum). The pylorus is usually free of fluid and so we can get a very clear picture of any lesions in this area. This is really important many performance horses have ulcers and erosions here that you would never know about unless they are completely scoped. The treatment is usually different from horses that only have squamous ulceration too, so this becomes crucial. We can then go into the first part of the small intestine (this is termed the duodenum) on most horses. Then as we retract the scope we can recheck the other side of the upper stomach and then pull back so the scope sits in the oesophagus. Clinical signs why you would consider scoping the stomach of your horse It is important to perform gastroscopy in horses that: 1) are grumpy I have learned that the owner and trainers are so accurate in their assessment of their horse s behaviour 2) are not performing as well as they had been - eg. suddenly a decrease in willingness to jump don t assume it is a back problem 3) have a decreased appetite OR when they will eat hay/pasture, but not grain and concentrate 4) have a low packed cell volume (pcv) (ANAEMIC) and sometimes a low albumin measurements. Sometimes these values are just low normal, but it may be enough that you want to check. In cases of stomach ulceration, there may be a loss of red blood cells and protein into the gastro-intestinal tract (i.e. the stomach and in cases of right dorsal colitis into the lumen of the large bowel). NOTE: Right dorsal colitis is an ulcerative inflammatory process in the large colon of horses, often associated with the administration of medications like phenylbutasone (Bute) or Flunixin and aspirin etc.. 5) occasionally have increases in liver enzymes if the duodenum (eg. foals) or pyloruis is involved there may be changes to motility of the duodenum which MAY facilitate ascending cholangiohepatitis in rare cases. 6) have a poor hair coat 7) has excessive salivation more common in foals (see Figure 7) 8) grinds his/her teeth 9) are losing weight or just not quite as heavy as one would like for the horse s height and feed intake 10) have soft manure not quite formed and you don t have a green grass or feed change reason 11) have colic signs especially when there is a history of mild to moderate, chronic, intermittent abdominal pain 12) have a history of non steroidal anti-inflammatory drugs. NSAIDs include Phenylbutasone (bute), Flunixin meglumine (for example Finadyne ), Ketoprofen, dipyrone (for example Buscopan ), and aspirin (which is sometimes used for patients with heart problems, laminitis and chronic uveitis (a particular eye problem)
Figure 4: The non-glandular (squamous) stomach lining with extreme hyperkeratosis (thickening) and a large, perforating ulcer in the glandular lining (mucosa) in a young horse that required euthanasia, due to excessive NSAID (phenylbutasone) use by the owner. The non-glandular (squamous) mucosa is pale and at the top and the glandular mucosa is pink. Treating ulcers For many years it has been thought that most ulcerative lesions and erosions and hyperkeratosis (thickening of the lining when they are ulcerating and trying to heal) are typically in the squamous mucosa. Whilst this is the area that is most commonly affected, data from retrospective studies and anecdotal clinical data have shown conclusively that pyloric lesions occur in a large percentage of performance horses. This is imperative to know because it changes how we treat horses with gastric ulceration. You should ask your vet if he/she can scope the pylorus if your horse has been colicing intermittently or if you want a complete exam. However, be warned if you don t hold your horse off feed properly then the vet can t get there. It is not enough to say that your horse is off his feed, because invariably there is a surprising amount of feed down in the stomach body, blocking the way to the pylorus and duodenum. Treatments that decrease acid (increase the ph) in the stomach We are very lucky to have omeprazole (a proton pump inhibitor it is the best way of modifying and increasing the stomach ph) widely available now for horses. Examples of this medication are Gastrozol and Gastroshield in Australia. Histamine 2 receptor antagonists. These include ranitidine (Ulcergard in Australia) and famotadine and cimetidine (rarely used anymore) Another that many clients ask about are the ANTACIDS these can work but only for about 1-2 hours, so not very convenient in a horse, but might help to decrease some pain associated with acidic stomach contents if you have just diagnosed it in a colicy horse. The only other time when they might be used strategically is if you have a horse about to gallop and it could be given 60-90 minutes before, so that stomach contents pushed upto the cardia during fast exercise have a higher ph. However, mostly these are not useful in horses.
Good prostaglandins Glandular lesions including the pyloric lesions appear to improve more if we have a medication, which is a prostaglandin E analogue (this is called misoprostol) i.e. the good prostaglandins that help the lining of the stomach, duodenum and even large bowel (eg. right dorsal colon) heal. These good prostaglandins are decreased, along with the bad inflammatory prostaglandins, when we use NSAIDs (eg. Bute, flunixin). Sometimes sucralfate should be used as well, especially if either the oesophagus or right dorsal colon is affected sucralfate may increase local beneficial prostaglandins, but this has not been looked at specifically in horses. The medication regimen has to be really closely looked at because it does change depending on the location and severity of ulcers, and also for safety reasons the owner/trainer must be informed about all medications (eg. the Prostaglandin E analogue should not be handled by asthmatic people or pregnant women or administered to pregnant fillies/mares). Controlling colic without NSAIDs (including Phenylbutasone, dipyrone, Flunixin, Ketoprofen and aspirin) ask your vet to use drugs other than NSAIDs if your horse has been diagnosed with ulcers and is still having intermittent colic bouts that require medical treatment. Some suggestions would include xylazine and butorphanol, which do not cause or exacerbate ulcers of the stomach and bowel in horses. Antibiotics It is possible that a novel Helicobacter species (not exactly the same as the human bacterium of the stomach named Helicobacter pylori) is involved in ulcers. Sometimes when we are having problems healing ulcers we use Metronidazole, which is an antibiotic. It may also work in that it helps if there is a local peritonitis. Other methods There are other methods that are useful when setting up a treatment regimen or prophylactic regimen including the use of lucerne hay (it is not known whether this is useful in healing ulcers because of its protein or calcium level). Other feed additives that are being researched or have been researched in other species include: corn oil [may modify volatile fatty acid (VFA) type] psyllium powdered calcium carbonate probiotics