Download GASTRIC ULCERATION

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