Horse colic
Encyclopedia
Colic in horse
s is defined as abdominal pain
, but it is a clinical sign rather than a diagnosis. The term colic can encompass all forms of gastrointestinal
conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. The most common forms of colic are gastrointestinal in nature and are most often related to colonic disturbance. There are a variety of different causes of colic, some of which can prove fatal without surgical intervention
. Colic surgery is usually an expensive procedure as it is major abdominal surgery, often with intensive aftercare. Among domesticated horses, colic is the leading cause of premature death. The incidence of colic in the general horse population has been estimated between 10 and 11 percent on an annual basis. It is important that any person who owns or works with horses be able to recognize the signs of colic and determine whether or not a veterinarian
should be called.
of food material (Water, Grass, Hay, Grain) at a part of the large bowel known as the pelvic flexure of the left colon
where the intestine takes a 180 degree turn and narrows. Impaction generally responds well to medical treatment, but more severe cases may not recover without surgery. If left untreated, severe impaction colic can be fatal. The most common cause is when the horse is on box rest and/or consumes large volumes of concentrated feed, or the horse has dental disease and is unable to masticate properly. This condition could be diagnosed on rectal examination by a veterinarian.
odic colic is the result of increased peristaltic contractions in the horse's gastrointestinal tract. It can be the result of a mild gas buildup within the horse's digestive tract. The signs of colic are generally mild and respond well to spasmolytic and analgesic
medication.
is the last part of the small intestine that ends in the cecum
. Ileal impaction can be caused by obstruction of ingesta. Other causes can be obstruction by ascarids (Parascaris equorum) or tapeworm (Anoplocephala Perfoliata) as mentioned below.
or oil and psyllium
husk. More recently doctors are treating cases with specific synbiotic (pro
and prebiotic) and psyllium combinations. Some cases may need surgery. Horses with sand or dirt impaction are predisposed to Salmonella
infection. Horses should not be fed from the ground in areas where sand, dirt and silt are prevalent although small amounts of sand or dirt will still be ingested by grazing. Management to reduce sand intake and prophylactic treatments with sand removal products are recommended by most veterinarians.
s in horses are round balls of mineral deposits often formed around a piece of ingested foreign material, such as sand or gravel. When they move from their original site they can obstruct the intestine. Enteroliths are not a common cause of colic, but are known to have a higher prevalence in states with a sandy soil and where an abundance of alfalfa hay is fed, such as California. Once a horse is diagnosed with colic due to enterolith it usually requires surgery to correct the condition.
. Deworming
heavily infected horses may cause a severe immune reaction to the dead worms, which can damage the intestinal wall and cause a fatal peritonitis
. Veterinarians often treat horses with suspected heavy worm burdens with corticosteroid
s to reduce the inflammatory
response to the dead worms. Blockages of the small intestine, particularly the ileum
, can occur with Parascaris equorum and may well require colic surgery. Large roundworm infestations are often the result of a poor deworming program. Horses develop immunity to parascarids between 6 months age and one year and so this condition is rare in adult horses.
have been implicated in causing colic. The most common species of tapeworm in the equine is Anoplocephala perfoliata. However, a 2008 study in Canada indicated that there is no connection between tapeworms and colic, contradicting studies performed in the UK.
e in the bowel wall, particularly if large numbers emerge simultaneously. The disease most frequently occurs in winter time. Pathological changes of the bowel reveal a typical "pepper and salt" colour of the large intestines. Animals suffering from cyathostominosis usually have a poor deworming history. There is now a lot of resistance to fenbendazole
in the UK.
and against the nephrosplenic ligament. It may necessitate surgery although often it can be treated with exercise and/or phenylephrine
, at times anesthesia and a rolling procedure, in which the horse is placed in left lateral recumbency and rolled to right lateral recumbency while jostling, must be performed to correct the condition medically. This condition can be diagnosed on rectal examination or through ultrasonography by a veterinarian.
of the blood supply means that it is a painful condition causing rapid deterioration and requiring emergency surgery.
is a form of colic in which a piece of intestine "telescopes" within a portion of itself. It most commonly happens in the small intestine of young horses and requires urgent surgery.
fatty tumor
s known as lipoma
s can form on the mesentery
. As the tumor enlarges, it stretches the connective tissue
into a stalk which can wrap around a segment of bowel, typically small intestine, cutting off its blood supply. The tumor forms a button that latches onto the stalk of the tumor, locking it on place, and requiring surgery for resolution.
(fluid buildup). As the bowel enlarges, it becomes less and less likely to be able to exit the site of entrapment. This problem also requires surgical correction.
in the stomach fairly commonly. Risk factors include confinement, infrequent feedings, a high proportion of concentrate feeds, such as grains, excessive non-steroid
al anti-inflammatory
drug use, and the stress of shipping and showing
. Gastric ulceration has also been associated with the consumption of cantharadin beatles in alfalfa hay which are very caustic when chewed and ingested. Most ulcers are treatable with medications that inhibit the acid producing cells of the stomach. Antacid
s are less effective in horses than in humans, because horses produce stomach acid almost constantly, while humans produce acid mainly when eating. Dietary management is critical. Bleeding ulcers leading to stomach rupture are rare.
of the horse. Signs of colic may be caused by problems other than the GI-tract e.g. problems in the kidney
s, ovaries
, spleen, testicular torsion, pleuritis, or pleuropneumonia. Diseases which sometimes cause symptoms which appear similar to colic include laminitis
and exertional rhabdomyolysis
.
s, strangulating
obstructions, and non-strangulating infarction
s.
formation, or foreign bodies. The primary pathophysiological
abnormality caused by this obstruction is related to the trapping of fluid within the intestine oral
to the obstruction. This is due to the large amount of fluid produced in the upper gastro-intestinal tract (around 125l daily), and the fact that this is primarily re-absorbed in parts of the intestine downstream from the obstruction.
The first problem with this degree of fluid loss from circulation is one of decreased plasma
volume, leading to a reduced cardiac output
, and acid-base disturbances
.
There also occur serious effects on the intestine itself, which becomes distended due to the trapped fluid, and by gas production from bacteria. It is this distension, and subsequent activation
of stretch receptor
s within the intestinal wall, that leads to the associated pain. With progressive distension of the intestinal wall, there is occlusion
of blood vessels, firstly veins, then arteries. The difference in time to onset of occlusion is due to the relatively more rigid walls of arteries compared with veins. This impairment of blood supply leads firstly to hyperaemia
and congestion
, and ultimately to ischaemic necrosis
and cellular death. The poor blood supply also has effects on the vascular
endothelium
, leading to an increased permeability
. This results initially in leakage of plasma, and eventually blood into the intestinal lumen
. In the opposite fashion, gram-negative
bacteria and endotoxin
s can enter the bloodstream, leading to further systemic effects.
s, volvulus
and displacement of intestine through a hole, such as a hernia
, a mesenteric rent, or the epiploic foramen.
larva
e, which develop within the (primarily cranial) mesenteric artery.
.
treatment. However, the most important factor is time elapsed since onset of clinical signs, as this has a profound impact on prognosis, and the type of treatment that will be undertaken.
, and endotoxemia. The rate should be measured over time, and its response to analgesic
therapy ascertained. A pulse that continues to rise in the face of adequate analgesia is considered a surgical indication.
Mucous membrane
colour can be assessed to appreciate the severity of haemodynamic compromise. Reddening of membranes reflects worse prognosis, and cyanotic
membranes indicate a very poor chance of a positive outcome.
Laboratory tests can be performed to assess the cardiovascular status of the patient. Packed Cell Volume (PCV) is a measure of hydration status, with a value 45% being considered significant. Increasing values over repeated examination are also considered significant. The total protein (TP) of blood may also be measured, as an aid in estimating the amount of protein loss into the intestine. Its value must be interpreted along with the PCV, to take into account the hydration status.
ed from the stomach, and any more than 2 litres of fluid is considered to be significant. Increased fluid is generally as a result of backing up of fluid through the intestinal tract, due to a downstream obstruction. This finding is important as it represents a relatively advanced stage of colic, and is often a surgical indication. Therapeutically, gastric decompression is important, as if fluid build up occurs, gastric rupture may occur, which is inevitably fatal.
can be useful in assessing the state of the intestines. A sanguinous
fluid represents an infarction
, and usually indicates surgery is necessary. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels.
is usually indicative of a condition affecting the large intestines, as distension of structures upstream of here would not be large enough to be visible externally.
of the abdomen, usually performed in a four quadrant approach, can be a useful tool. Increased gut sounds are not usually found with major changes, and may be indicative of spasmodic colic. A decreased amount of sound, or no sound, may be suggestive of serious changes.
produced, and its character can be helpful, although as changes often occur relatively distant to the anus, changes may not be seen for some time. In areas where sand colic is known to be common, or if the history suggests it may be a possibility, faeces can be examined for the presence of sand, often by immersion in water, or simply by its texture.
s, providing clean feed and drinking water, preventing the ingestion of dirt or sand by using an elevated feeding surface, a regular feeding
schedule, regular deworming
, regular dental care
, a regular diet that does not change substantially in content or proportion and prevention of heatstroke
. Horses that bolt
their feed are at risk of colic, and several management techniques may be used to slow down the rate of feed consumption.
Turnout is thought to reduce the likelihood of colic, although this has not been proven. It is recommended that a horse receive ideally 18 hours of grazing time each day, as in the wild. However, many times this is difficult to manage with competition horses and those that are boarded, as well as for animals that are easy keeper
s with access to lush pasture and hence at risk of laminitis
. Turnout on a dry lot with lower-quality fodder may have similar beneficial effects.
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s is defined as abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, but it is a clinical sign rather than a diagnosis. The term colic can encompass all forms of gastrointestinal
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. The most common forms of colic are gastrointestinal in nature and are most often related to colonic disturbance. There are a variety of different causes of colic, some of which can prove fatal without surgical intervention
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
. Colic surgery is usually an expensive procedure as it is major abdominal surgery, often with intensive aftercare. Among domesticated horses, colic is the leading cause of premature death. The incidence of colic in the general horse population has been estimated between 10 and 11 percent on an annual basis. It is important that any person who owns or works with horses be able to recognize the signs of colic and determine whether or not a veterinarian
Veterinarian
A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....
should be called.
Types
This list of types of colic is not exhaustive but details some of the types which may be encountered.Pelvic flexure impaction
This is caused by an impactionImpaction
Impaction, from the Latin impingere, is a medical term used to describe several different types of blockage.- In Reptiles : Impaction occurs in reptiles when they consume something that they cannot digest. Common causes of impaction are rocks and sand which might be accidentally consumed when the...
of food material (Water, Grass, Hay, Grain) at a part of the large bowel known as the pelvic flexure of the left colon
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
where the intestine takes a 180 degree turn and narrows. Impaction generally responds well to medical treatment, but more severe cases may not recover without surgery. If left untreated, severe impaction colic can be fatal. The most common cause is when the horse is on box rest and/or consumes large volumes of concentrated feed, or the horse has dental disease and is unable to masticate properly. This condition could be diagnosed on rectal examination by a veterinarian.
Spasmodic colic
SpasmSpasm
In medicine a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes...
odic colic is the result of increased peristaltic contractions in the horse's gastrointestinal tract. It can be the result of a mild gas buildup within the horse's digestive tract. The signs of colic are generally mild and respond well to spasmolytic and analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....
medication.
Ileal impaction
The ileumIleum
The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum.The ileum follows the duodenum...
is the last part of the small intestine that ends in the cecum
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
. Ileal impaction can be caused by obstruction of ingesta. Other causes can be obstruction by ascarids (Parascaris equorum) or tapeworm (Anoplocephala Perfoliata) as mentioned below.
Sand impaction
This is most likely to occur in horses that graze sandy or heavily grazed pastures leaving only dirt to ingest. The term sand also encompasses dirt. The ingested sand or dirt accumulates in the pelvic flexure, right dorsal colon and the cecum of the large intestines. As the sand or dirt irritates the lining of the bowel it can cause diarrhea. The weight and abrasion of the sand or dirt causes the bowel wall to become inflamed and can cause a reduction in colonic motility and in severe cases even peritonitis. Historically medical treatment of the problem is with laxatives such as liquid paraffinParaffin
In chemistry, paraffin is a term that can be used synonymously with "alkane", indicating hydrocarbons with the general formula CnH2n+2. Paraffin wax refers to a mixture of alkanes that falls within the 20 ≤ n ≤ 40 range; they are found in the solid state at room temperature and begin to enter the...
or oil and psyllium
Psyllium
Psyllium , or Ispaghula , is the common name used for several members of the plant genus Plantago whose seeds are used commercially for the production of mucilage.-History:...
husk. More recently doctors are treating cases with specific synbiotic (pro
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
and prebiotic) and psyllium combinations. Some cases may need surgery. Horses with sand or dirt impaction are predisposed to Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
infection. Horses should not be fed from the ground in areas where sand, dirt and silt are prevalent although small amounts of sand or dirt will still be ingested by grazing. Management to reduce sand intake and prophylactic treatments with sand removal products are recommended by most veterinarians.
Enterolith
EnterolithEnterolith
An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting...
s in horses are round balls of mineral deposits often formed around a piece of ingested foreign material, such as sand or gravel. When they move from their original site they can obstruct the intestine. Enteroliths are not a common cause of colic, but are known to have a higher prevalence in states with a sandy soil and where an abundance of alfalfa hay is fed, such as California. Once a horse is diagnosed with colic due to enterolith it usually requires surgery to correct the condition.
Large roundworms
Occasionally there can be an obstruction by large numbers of roundworms. This is most commonly seen in young horses as a result of a very heavy infestation of Parascaris equorum that can subsequently cause a blockage and rupture of the small intestineSmall intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
. Deworming
Deworming
Deworming is the giving of an anthelmintic drug to an animal to rid it of intestinal parasites, such as roundworm and tapeworm...
heavily infected horses may cause a severe immune reaction to the dead worms, which can damage the intestinal wall and cause a fatal peritonitis
Peritonitis
Peritonitis is an inflammation of the peritoneum, the serous membrane that lines part of the abdominal cavity and viscera. Peritonitis may be localised or generalised, and may result from infection or from a non-infectious process.-Abdominal pain and tenderness:The main manifestations of...
. Veterinarians often treat horses with suspected heavy worm burdens with corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s to reduce the inflammatory
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
response to the dead worms. Blockages of the small intestine, particularly the ileum
Ileum
The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum.The ileum follows the duodenum...
, can occur with Parascaris equorum and may well require colic surgery. Large roundworm infestations are often the result of a poor deworming program. Horses develop immunity to parascarids between 6 months age and one year and so this condition is rare in adult horses.
Tapeworms
Tapeworms at the junction of the cecumCecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
have been implicated in causing colic. The most common species of tapeworm in the equine is Anoplocephala perfoliata. However, a 2008 study in Canada indicated that there is no connection between tapeworms and colic, contradicting studies performed in the UK.
Cyathostomes
Acute diarrhoea can be caused by cyathostomes or "small Stronglus type" worms that are encysted as larvaLarva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e in the bowel wall, particularly if large numbers emerge simultaneously. The disease most frequently occurs in winter time. Pathological changes of the bowel reveal a typical "pepper and salt" colour of the large intestines. Animals suffering from cyathostominosis usually have a poor deworming history. There is now a lot of resistance to fenbendazole
Fenbendazole
Fenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including roundworms, hookworms, whipworms, the taenia species of tapeworms, pinworms, aelurostrongylus, paragonimiasis, strongyles and strongyloides and can be administered to sheep, cattle,...
in the UK.
Left dorsal displacement
Left dorsal displacement is a form of colic where the left dorsal colon becomes trapped above the spleenSpleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
and against the nephrosplenic ligament. It may necessitate surgery although often it can be treated with exercise and/or phenylephrine
Phenylephrine
Phenylephrine is a selective α1-adrenergic receptor agonist used primarily as a decongestant, as an agent to dilate the pupil, and to increase blood pressure...
, at times anesthesia and a rolling procedure, in which the horse is placed in left lateral recumbency and rolled to right lateral recumbency while jostling, must be performed to correct the condition medically. This condition can be diagnosed on rectal examination or through ultrasonography by a veterinarian.
Right dorsal displacement
Right dorsal displacement is another displacement of part of the large bowel. Although signs of colic may not be very severe, surgery is usually the only available treatment.Torsion
Various parts of the horse's gastrointestinal tract may twist upon themselves. It is most likely to be either small intestine or part of the colon. OcclusionVascular occlusion
Vascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
of the blood supply means that it is a painful condition causing rapid deterioration and requiring emergency surgery.
Intussusception
IntussusceptionIntussusception (medical disorder)
An intussusception is a medical condition in which a part of the intestine has invaginated into another section of intestine, similar to the way in which the parts of a collapsible telescope slide into one another. This can often result in an obstruction...
is a form of colic in which a piece of intestine "telescopes" within a portion of itself. It most commonly happens in the small intestine of young horses and requires urgent surgery.
Epiploic foramen entrapment
On rare occasions, a piece of small intestine can become trapped through the epiploic foramen. The blood supply to this piece of intestine is immediately occluded. The intestine becomes trapped and surgery is the only available treatment.Strangulating lipoma
BenignBenign
A benign tumor is a tumor that lacks the ability to metastasize. Common examples of benign tumors include moles and uterine fibroids.The term "benign" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health...
fatty tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
s known as lipoma
Lipoma
A lipoma is a benign tumor composed of adipose tissue. It is the most common form of soft tissue tumor. Lipomas are soft to the touch, usually movable, and are generally painless. Many lipomas are small but can enlarge to sizes greater than six centimeters. Lipomas are commonly found in adults...
s can form on the mesentery
Mesentery
In anatomy, the mesentery is the double layer of peritoneum that suspends the jejunum and ileum from the posterior wall of the abdomen. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.-Mesentery :The...
. As the tumor enlarges, it stretches the connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
into a stalk which can wrap around a segment of bowel, typically small intestine, cutting off its blood supply. The tumor forms a button that latches onto the stalk of the tumor, locking it on place, and requiring surgery for resolution.
Mesenteric rent entrapment
The mesentery is a thin sheet attached to the entire length of intestine, enclosing blood vessels, lymph nodes, and nerves. Occasionally, a small rent (hole) can form in the mesentery, through which a segment of bowel can occasionally enter. As in epiploic foramen entrapment, the bowel first enlarges, since arteries do not occlude as easily as veins, which causes edemaEdema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
(fluid buildup). As the bowel enlarges, it becomes less and less likely to be able to exit the site of entrapment. This problem also requires surgical correction.
Gastric ulceration
Horses form ulcersPeptic ulcer
A peptic ulcer, also known as PUD or peptic ulcer disease, is the most common ulcer of an area of the gastrointestinal tract that is usually acidic and thus extremely painful. It is defined as mucosal erosions equal to or greater than 0.5 cm...
in the stomach fairly commonly. Risk factors include confinement, infrequent feedings, a high proportion of concentrate feeds, such as grains, excessive non-steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
al anti-inflammatory
Anti-inflammatory
Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....
drug use, and the stress of shipping and showing
Horse show
A Horse show is a judged exhibition of horses and ponies. Many different horse breeds and equestrian disciplines hold competitions worldwide, from local to the international levels. Most horse shows run from one to three days, sometimes longer for major, all-breed events or national and...
. Gastric ulceration has also been associated with the consumption of cantharadin beatles in alfalfa hay which are very caustic when chewed and ingested. Most ulcers are treatable with medications that inhibit the acid producing cells of the stomach. Antacid
Antacid
An antacid is a substance which neutralizes stomach acidity.-Mechanism of action:Antacids perform a neutralization reaction, increasing the pH to reduce acidity in the stomach. When gastric hydrochloric acid reaches the nerves in the gastrointestinal mucosa, they signal pain to the central nervous...
s are less effective in horses than in humans, because horses produce stomach acid almost constantly, while humans produce acid mainly when eating. Dietary management is critical. Bleeding ulcers leading to stomach rupture are rare.
Other causes that may show clinical symptoms of colic
Strictly speaking colic refers only to signs originating from the gastrointestinal tractGastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
of the horse. Signs of colic may be caused by problems other than the GI-tract e.g. problems in the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
s, ovaries
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
, spleen, testicular torsion, pleuritis, or pleuropneumonia. Diseases which sometimes cause symptoms which appear similar to colic include laminitis
Laminitis
Laminitis is a disease that affects the feet of ungulates. It is best known in horses and cattle. Symptoms include lameness, and increased temperature in the hooves...
and exertional rhabdomyolysis
Rhabdomyolysis
Rhabdomyolysis is a condition in which damaged skeletal muscle tissue breaks down rapidly. Breakdown products of damaged muscle cells are released into the bloodstream; some of these, such as the protein myoglobin, are harmful to the kidneys and may lead to kidney failure...
.
Pathophysiology of equine colic
This can be divided broadly into simple obstructionObstruction
Obstruction may refer to:* Obstruction theory, in mathematics* Obstruction of justice, the crime of interfering with law enforcement* Obstructing government administration* Propagation path obstruction** Single Vegetative Obstruction Model-Medical:...
s, strangulating
Strangulating
Strangulating is the process of constricting blood vessels which cause arrest in the flow of blood to a tissue....
obstructions, and non-strangulating infarction
Infarction
In medicine, infarction refers to tissue death that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.-Causes:...
s.
Simple Obstruction
This is characterised by a physical obstruction of the intestine, which can be due to impacted food material, strictureStricture
Stricture may refer to:* esophageal stricture, in medicine* stenosis, in medicine* a feature of the Perl programming language* tenet, in religion* degree of contact, in a consonant...
formation, or foreign bodies. The primary pathophysiological
Pathophysiology
Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
abnormality caused by this obstruction is related to the trapping of fluid within the intestine oral
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
to the obstruction. This is due to the large amount of fluid produced in the upper gastro-intestinal tract (around 125l daily), and the fact that this is primarily re-absorbed in parts of the intestine downstream from the obstruction.
The first problem with this degree of fluid loss from circulation is one of decreased plasma
Blood plasma
Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
volume, leading to a reduced cardiac output
Cardiac output
Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...
, and acid-base disturbances
Acid-base imbalance
Acid–base imbalance is an abnormality of the human body's normal balance of acids and bases that causes the plasma pH to deviate out of the normal range . In the fetus, the normal range differs based on which umbilical vessel is sampled...
.
There also occur serious effects on the intestine itself, which becomes distended due to the trapped fluid, and by gas production from bacteria. It is this distension, and subsequent activation
Activation
Activation in chemical sciences generally refers to the process whereby something is prepared or excited for a subsequent reaction.- Chemistry :...
of stretch receptor
Stretch receptor
Stretch receptors are mechanoreceptors responsive to distention of various organs and muscles, and are neurologically linked to the medulla in the brain stem via afferent nerve fibers...
s within the intestinal wall, that leads to the associated pain. With progressive distension of the intestinal wall, there is occlusion
Vascular occlusion
Vascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
of blood vessels, firstly veins, then arteries. The difference in time to onset of occlusion is due to the relatively more rigid walls of arteries compared with veins. This impairment of blood supply leads firstly to hyperaemia
Hyperaemia
Hyperaemia or hyperemia describes the increase of blood flow to different tissues in the body. It can have medical implications, but is also a regulatory response, allowing change in blood supply to different tissues through vasodilation. Clinically, hyperaemia in tissues manifest as erythema,...
and congestion
Congestion
Congestion generally means excessive crowding.Congestion may refer to:* congestion in heart failure, a term to describe low cardiac output seen in heart failure.* Nasal congestion, the blockage of nasal passages due to swollen membranes...
, and ultimately to ischaemic necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
and cellular death. The poor blood supply also has effects on the vascular
Vascular
Vascular in zoology and medicine means "related to blood vessels", which are part of the circulatory system. An organ or tissue that is vascularized is heavily endowed with blood vessels and thus richly supplied with blood....
endothelium
Endothelium
The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...
, leading to an increased permeability
Vascular permeability
Vascular permeability, often in the form of capillary permeability, characterizes the capacity of a blood vessel wall to allow for the flow of small molecules or even whole cells in and out of the vessel. Blood vessel walls are lined by a single layer of endothelial cells...
. This results initially in leakage of plasma, and eventually blood into the intestinal lumen
Lumen (anatomy)
A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
. In the opposite fashion, gram-negative
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
bacteria and endotoxin
Endotoxin
Endotoxins are toxins associated with some Gram-negative bacteria. An "endotoxin" is a toxin that is a structural molecule of the bacteria that is recognized by the immune system.-Gram negative:...
s can enter the bloodstream, leading to further systemic effects.
Strangulating Obstruction
Strangulating obstructions have all the same pathological features as a simple obstruction, but the blood supply is immediately affected. Both arteries and veins may be affected immediately, or progressively as in simple obstruction. Common causes of strangulating obstruction are intussusceptionIntussusception
Intussusception may refer to:* Intussusception * Intussusception...
s, volvulus
Volvulus
A volvulus is a bowel obstruction with a loop of bowel whose nose has abnormally twisted on itself.-Types:* Volvulus Neonatorum.* Volvulus Small Intestine.* Volvulus Caecum.* Volvulus Sigmoid Colon .* Gastric volvulus....
and displacement of intestine through a hole, such as a hernia
Hernia
A hernia is the protrusion of an organ or the fascia of an organ through the wall of the cavity that normally contains it. A hiatal hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm....
, a mesenteric rent, or the epiploic foramen.
Non-strangulating Infarction
In a non-strangulating infarction, blood supply to a section of intestine is occluded, without any obstruction to ingesta present within the intestinal lumen. The most common cause is infection with Strongylus vulgarisStrongylus vulgaris
Strongylus vulgaris, commonly known as the blood worm, is a common horse parasite in the phylum Nematoda. It generally lives in the large intestine and migrates in the mesenteric arteries. This nematode is considered to be one of the "most pathogenic" of the large strongyles subphylum and is...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, which develop within the (primarily cranial) mesenteric artery.
Diagnosis
Many different diagnostic tests can be used to diagnose the cause of equine colic, which may have greater or lesser value in certain situations. The most important distinction to make is whether the condition should be managed medically or surgically. If surgery is indicated, then it must be performed with utmost haste, as delay is a dire prognostic indicatorPrognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
.
History
A thorough history is always taken, including age, sex, recent activity, diet, any recent dietary changes, and routine anthelminticAnthelmintic
Anthelmintics or antihelminthics are drugs that expel parasitic worms from the body, by either stunning or killing them. They may also be called vermifuges or vermicides .-Pharmaceutical classes:...
treatment. However, the most important factor is time elapsed since onset of clinical signs, as this has a profound impact on prognosis, and the type of treatment that will be undertaken.
Cardiovascular Parameters
Heart rate rises with progression of colic, in part due to pain, but mainly due to decreased circulating volume, decreased preloadPreload
In cardiac physiology, preload is the end volumetric pressure that stretches the right or left ventricle of the heart to its greatest geometric dimensions under variable physiologic demand...
, and endotoxemia. The rate should be measured over time, and its response to analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....
therapy ascertained. A pulse that continues to rise in the face of adequate analgesia is considered a surgical indication.
Mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...
colour can be assessed to appreciate the severity of haemodynamic compromise. Reddening of membranes reflects worse prognosis, and cyanotic
Cyanosis
Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...
membranes indicate a very poor chance of a positive outcome.
Laboratory tests can be performed to assess the cardiovascular status of the patient. Packed Cell Volume (PCV) is a measure of hydration status, with a value 45% being considered significant. Increasing values over repeated examination are also considered significant. The total protein (TP) of blood may also be measured, as an aid in estimating the amount of protein loss into the intestine. Its value must be interpreted along with the PCV, to take into account the hydration status.
Rectal Examination
Repeated rectal examinations are a cornerstone of colic diagnosis, as many large intestinal conditions can be definitively diagnosed by this method alone. Other non-specific findings, such as dilated small intestinal loops, may also be detected, and can play a major part in determining if surgery is necessary.Naso-gastric Intubation
Passing a Naso-Gastric Tube (NGT) is useful both diagnostically and therapeutically. Fluid is refluxReflux
Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations...
ed from the stomach, and any more than 2 litres of fluid is considered to be significant. Increased fluid is generally as a result of backing up of fluid through the intestinal tract, due to a downstream obstruction. This finding is important as it represents a relatively advanced stage of colic, and is often a surgical indication. Therapeutically, gastric decompression is important, as if fluid build up occurs, gastric rupture may occur, which is inevitably fatal.
Abdominocentesis
The extraction of fluid from the peritoneumPeritoneum
The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal organs — in amniotes and some invertebrates...
can be useful in assessing the state of the intestines. A sanguinous
Sanguine
Sanguine is chalk of a reddish color, often called the true colour of blood. tending to brown, used in drawing, The word also describes any drawing done in sanguine.-Technique:...
fluid represents an infarction
Infarction
In medicine, infarction refers to tissue death that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.-Causes:...
, and usually indicates surgery is necessary. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels.
Abdominal Distension
Any degree of abdominal distensionDistension
Distension generally refers to an enlargement or ballooning effect:* Gastric distension - bloating of the stomach when air is pumped into it, as in a medical procedure* Abdominal distension - abdominal bloating, a symptom of several medical conditions...
is usually indicative of a condition affecting the large intestines, as distension of structures upstream of here would not be large enough to be visible externally.
Auscultation
AuscultationAuscultation
Auscultation is the term for listening to the internal sounds of the body, usually using a stethoscope...
of the abdomen, usually performed in a four quadrant approach, can be a useful tool. Increased gut sounds are not usually found with major changes, and may be indicative of spasmodic colic. A decreased amount of sound, or no sound, may be suggestive of serious changes.
Fecal Examination
The amount of fecesFeces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
produced, and its character can be helpful, although as changes often occur relatively distant to the anus, changes may not be seen for some time. In areas where sand colic is known to be common, or if the history suggests it may be a possibility, faeces can be examined for the presence of sand, often by immersion in water, or simply by its texture.
Clinical signs
- Pawing and/or scraping
- Stretching
- Frequent attempts to urinate
- Flank watching: turning of the head to watch the stomach and/or hind quarters
- Biting/nipping the stomach
- Pacing
- Repeated flehmen response
- Repeated lying down and rising
- Rolling
- Groaning
- BruxismBruxismBruxism is characterized by the grinding of the teeth and typically includes the clenching of the jaw. It is an oral parafunctional activity that occurs in most humans at some time in their lives. In most people, bruxism is mild enough not to be a health problem...
- Excess salivation
- Loss of appetite
- Decreased fecal output
- Increased pulse rate
- Dark mucous membranes
Prevention
The incidence of colic can be reduced by restricted access to simple carbohydrateCarbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
s, providing clean feed and drinking water, preventing the ingestion of dirt or sand by using an elevated feeding surface, a regular feeding
Equine nutrition
Equine nutrition is the feeding of horses, ponies, mules, donkeys, and other equines. Correct and balanced nutrition is a critical component of proper horse care....
schedule, regular deworming
Deworming
Deworming is the giving of an anthelmintic drug to an animal to rid it of intestinal parasites, such as roundworm and tapeworm...
, regular dental care
Horse teeth
Horses' teeth are often used to estimate the animal's age, hence the sayings "long in the tooth", "straight from the horse's mouth" and "Don't look a gift horse in the mouth".- Types of teeth :At five years of age a horse has between 36 and 44 teeth...
, a regular diet that does not change substantially in content or proportion and prevention of heatstroke
Hyperthermia
Hyperthermia is an elevated body temperature due to failed thermoregulation. Hyperthermia occurs when the body produces or absorbs more heat than it can dissipate...
. Horses that bolt
Bolting (horse)
Bolting when referring to equidae, generally refers to two different equine behaviors, both undesirable: the practice of running away without control, and the practice of eating food at a dangerously fast rate. However, there are other meanings as well...
their feed are at risk of colic, and several management techniques may be used to slow down the rate of feed consumption.
Turnout is thought to reduce the likelihood of colic, although this has not been proven. It is recommended that a horse receive ideally 18 hours of grazing time each day, as in the wild. However, many times this is difficult to manage with competition horses and those that are boarded, as well as for animals that are easy keeper
Easy keeper
An easy keeper, easy doer or good doer is a livestock animal that can live on relatively little food. The opposite of an easy keeper is a hard keeper , an animal that is prone to be too thin and has difficulty maintaining adequate weight.Easy keepers tend to be found most often in breeds...
s with access to lush pasture and hence at risk of laminitis
Laminitis
Laminitis is a disease that affects the feet of ungulates. It is best known in horses and cattle. Symptoms include lameness, and increased temperature in the hooves...
. Turnout on a dry lot with lower-quality fodder may have similar beneficial effects.
Further reading
- The Illustrated Veterinary Encyclopedia for Horsemen Equine Research Inc.
- Veterinary Medications and Treatments for Horsemen Equine Research Inc.
- Horse Owner's Veterinary Handbook James M. Giffin, M.D. and Tom Gore, D.V.M.
- Preventing Colic in Horses Christine King, BVSc, MACVSc