EQUINE COLIC Part 2 Terminology used in describing colics
Dr. Grahame Best
Ranvet Pty Ltd
As briefly described in Part 1, colic is a condition of abdominal pain
rather than a single disease. Causes are numerous, and sometimes
difficult to diagnose accurately, because a number of digestive tract
disorders result in colic.
By location, the following list describes commonly observed disorders
which result in colic:
Ulcers, impactions, tumors and distension of the
stomach
Impactions, enteritis, displacements, torsion, ileus, infarctions,
obstructions and intussusceptions of the small intestine
Impaction, perforation, torsion, intussusception and infarction of the
caecum
Gaseous distension, impaction, enteroliths, torsions, displacements,
strangulation, obstruction and ulcerative colitis of the large colon
Obstruction and impaction of the small colon
Peritonitis (inflammation of the abdominal cavity)
In addition, most colics can be classified as belonging to one of three
types;
Intestinal dysfunction the horses digestive tract is not working
properly. This is the most common category, and includes gas distension,
impaction, spasms and paralysis (ileus)
Intestinal accidents where the intestines are injured or torn. These
are less common than the category above, and include displacements,
torsions and hernias. The intestinal accidents almost always require
surgery.
Enteritis or ulcerations these are colics caused by infections,
inflammations and other intestinal disease, including parasitism and
stress
Depending on the cause of the colic, the horse intestine will show one
of two types of disruption;
Increased gut activity (hyperperistalsis), where gut movement is
increased above normal. This is seen with parasitism, mouldy hay, excess
grain or forage. If you hear significant amounts of gas rumbling when
you place your ear against the flank and the horse is passing manure,
you are most likely seeing an increased gut activity colic. The outcome
from these is usually very favourable.
Decreased gut activity (hypoperistalsis), where gut activity is
reduced, or non existent. This can be caused by excess parasites, grain
overload, sudden feed changes, cold water in hot horses. If you hear
decreased gut sounds, or none at all, and the horse is not passing
manure, and appears to be in acute pain, this is a serious potential
situation and requires veterinary advice and action rapidly
Because many of the terms used in the diagnosis, treatment of, and
literature about, colic are unfamiliar to horse owners, the descriptions
below will assist owners to understand some of the frequently used
terms, in the hope of providing better understanding:
Caecum at the junction of the small and large intestines, the horse
gut has a large sac over 1 metre long, with a capacity of 25-30 litres.
This is the caecum the equine version of the human appendix. Food
passes into the caecum from the small intestine before entering the
large intestine.
Together, the caecum and large intestine form the fermentation chamber
for the horse, where microbes digest much of the fibre to produce energy
for the horse. (See Large Intestine)
Colic a condition of abdominal pain
Colitis inflammation of the colon (large intestine), often resulting
in diarrhoea
Displacement movement of a part of the intestine to an abnormal
location (usually resulting in a loss of function)
Distension abnormal enlargement of a part of the digestive tract that
results from pressure exerted by an accumulation of gas, liquid,
ingesta, or other materials. Commonly seen in the stomach.
Endotoxaemia increased amounts of endotoxins in the blood. Endotoxin
is a normal part of the cell membrane of microbes in the horse
intestine. Endotoxin is not usually absorbed into the blood unless the
intestinal lining is damaged. Endotoxaemia may result because of
increased growth of bacteria, or damage to their cell wall structure.
This can result in colic, damage to organs, circulatory disease and
death
.
Enteritis inflammation of the small intestine
Enteroliths stone-like concretions that form around a foreign body in
the digestive tract
Flatulence gas, as in flatulent colic in which abdominal pain is
accompanied by the passage of large amounts of gas.
Flexure a bend in a segment of intestine such as the pelvic flexure of
the large intestine
Functional obstruction decreased rate of passage of material through
the digestive tract with no evidence of damage to the anatomy of the
intestine
Gastric rupture gastric refers to the stomach. Rupture means breaking
of tissue. Gastric rupture occurs because of pressure exerted from
abnormal accumulations of materials in the stomach. Often seen when
horses gorge on grain, or on a substance which expands when wet, such as
dried Beet Pulp. Horses cannot vomit, so stomach contents have nowhere
to be expelled quickly as in dogs and man, and the stomach may burst.
Once this happens, death is inevitable.
Gastritis inflammation of the stomach
Impaction a physical blockage of a portion of the inner part of the
digestive tract caused by the presence of abnormally excessive amounts
of material. This includes impaction caused by heavily parasitised
horses and accumulation of excess feed ingesta. Impactions result in
accumulations of gas and ingesta.
Ileus a condition in which the bowel is not functioning to move lumen
contents at normal rates of flow along the digestive tract because of
lack of normal nerve and muscle control.
Infarction blockage of a blood vessel, usually an artery that supplies
an area of intestine. Often results in areas of devitalised (dead)
bowel, in similar fashion to infarction in the heart producing areas of
dead heart muscle with subsequent heart attack in man. Infarction in
horses is most commonly caused by intestinal parasites.
Intussusception telescoping of the intestine in which one segment of
the intestine passes inside an adjacent segment of the intestine
(telescoping), which causes occlusion (blockage) of the lumen , and
often of the blood supply to that area, as well.
Large Intestine 3-4 metres long, with a diameter of 20-25cm along most
of its length, and a capacity of over 50 litres, the large intestine
fills a significant part of the abdomen. Surprisingly, this large
structure is attached to the body wall at only two points: at its
beginning where it joins the small intestine and caecum, and at its end
where it joins the short, narrow small colon which leads to the anus.
With only two fixed points, the large intestine lies in the abdomen in a
neat double-U formation, with one U stacked up on top of the other.
This arrangement means that food must navigate around a number of 180
degree bends (flexures) in the intestine.
Lipoma benign fatty tumors that develop on the mesentery around the
digestive tract. Some are attached to the mesentery by a very long,
narrow stalk. These pedunculated lipomas may entwine around intestine
causing a strangulation obstruction.
Mechanical obstruction a blockage of the intestines caused by an
enterolith, accumulation of ingested feed (impaction), or by intestinal
displacement.
Mesentery the majority of the small intestine hangs like a curtain
from a membrane called the mesentery, which is attached to one point in
the middle of the abdomen under the spine. The small intestine looks
like a very long sausage running along the bottom of this thin curtain,
with the top of the curtain near the attachment to the body under the
spine quite bunched together
.
Peritonitis inflammation of the lining of the abdominal cavity (the
peritoneum)
Simple obstruction blockage in the lumen of the digestive tract by a
food mass or foreign material without disruption of normal blood flow.
Spasmodic colic colic due to increased intestinal contractions. These
abnormal spasms cause the intestine to contract painfully. Usually
respond well to treatment.
Strangulation obstruction blockage in the lumen of the intestine and
compromise of the blood flow to the bowel.
Torsion abnormal twisting of intestine
Volvulus involves twisting of the intestine on its mesentery. Torsion
and volvulus almost always cause a total blockage of the intestine and
require immediate surgery if the horse is to survive.
What Are The Major Signs of Colic?
Colic makes the horses behaviour alter to varying degrees, depending on
the severity of pain, and the severity of the lesion (type of colic).
Some of the more typical signs include;
Not eating, or changing in eating habits
Circling, laying down, rolling, laying down and rising frequently,
suddenly dropping to the ground, pawing.
Violent rolling
Reduced manure output, or altered manure consistency (dry and hard or
fluid)
Turning the head and looking at the flank or abdomen
Kicking at the abdomen, stretching out and standing for long periods
Anxious, trembling and sometimes sweating
Absence of, or increased bowel sounds
Increased heart and respiratory rate
Cool extremities
You can conduct several procedures yourself to help provide information
to your vet, and to help monitor the progress of any colic episode.
Learn to take the heart rate and respiratory rate. Resting heart rates
of over 50 beats per minute may indicate moderate to severe pain.
Breathing rate also increases with pain. Normal respiratory rate is
between 8-16 breaths per minute.
The mucous membranes (inside the lips) are normally pink and moist.
Purple, or grey, dry gums indicate circulation problems that suggest
severe colic
Learn to listen for gut sounds over the flank area. Lack of gut
sounds, or excessive gut sounds, can suggest severe problems. You can
put your ear against the flank if you have no stethoscope to do this,
but you will need to listen to a normal horse so you can identify what
you are listening to first. Are the gut sounds normal, increased,
decreased or absent?
Frequency of abdominal pain is it intermittent or continuous?
Is there manure? Is it dry, or moist?
What Are The Major Types of Colic?
Impaction Colic the most common colic. The intestine is blocked by a
large mass of food. Usually impactions occur in the large intestine at
one of the flexures. This is essentially constipation in horses. Usually
resolve fairly easily with appropriate treatment in most cases
Gas Colic sometimes gas builds up in the intestine, most commonly
in the large intestine and caecum. The gas distends the intestine,
causing pain. Usually resolve fairly easily with appropriate treatment
Spasmodic Colic some colics are due to increased intestinal
contractions, which appear to come and go regularly. These usually
resolve readily with appropriate treatment. Over 75% of colics are
spasmodic in many trials and surveys.
Displacement / Volvulus / Torsion (Twisted Bowel) Except in rare
cases these are medical emergencies if the horse is to survive. Early
cases can easily look like more benign colics, so it is important to
take all colic cases seriously.
Enteritis or Colitis inflammation of the intestines can cause colics.
These are serious medical cases requiring immediate veterinary
attention.
Gastric Distention or Rupture when horses gorge on grain or dried
beet pulp, for example, stomach contents expand dangerously. The horse
cannot vomit, so the stomach may burst. Death is then inevitable. Keep
grain locked away from horses!
Unknown many colic cases cannot be determined as to the actual
cause.
Be aware that one of the problems with colic is that it can be very
difficult in the early stages to distinguish a mild colic from a
potentially fatal colic. Treat all colics seriously!
Remember that the vast majority of colics (about 93%) are medical, and
can be treated with appropriate supportive treatment and pain relief
medication.
Remember also that three management factors are found to regularly
influence the onset of colic in horses;
Change in diet abrupt diet changes increase colics. Incidence of
colic increases with increases of grain in diets.
Change in stabling conditions
Change in activity
By now you will be beginning to understand the bewildering array of
issues your veterinarian must consider when dealing with equine colic.
The most effective thing you can do for your horse is to;
carefully consider and act on what you can do to reduce the risk of
colic
learn to take vital signs such as heart and respiratory rate
learn to observe your horses normal behaviour so you know when it is
abnormal
make sure you have a good relationship with your veterinarian.