Colic, the dreaded fear of horses, horse owners and veterinarians everywhere. Colic has been called the number one killer of horses and accounts for a large proportion of the emergency situations that horse owners and veterinarians must deal with. Colic is not a specific disease, but rather a combination of signs that signal the presence of abdominal pain in horses. These signs can range in severity from mild to severe, and can become a life threatening situation. It is imperative at the onset of acute colic, that prompt veterinary care is sought to maximize the chance for complete recovery.
Some of the most common clinical signs encountered that represent the presence of abdominal pain in horses are:
· Turning the head toward the flank
· Pawing
· Kicking or biting at the abdomen
· Stretching out as if to urinate
· Repeatedly lying down and getting up or attempting to do so
· Rolling, especially violent rolling
· Sitting in a dog-like position, or lying on the back
· Lack of appetite (anorexia)
· Putting head down to water without drinking
· Lack of bowel movements, as evidenced by the small number of manure piles
· Absence of, or reduced, digestive sounds
· Sweating
· Rapid respiration and/or flared nostrils
· Elevated pulse rate (greater than 52 beats per minute)
· Depression
· Lip curling (Flehmen response)
· Cool extremities
The digestive tract in the horse has become well adapted over millions of years to grazing small amounts of grass nearly continuously. It consists basically of a very long muscular tube (about 100 feet in total) consisting of 6 basic parts: the esophagus, the stomach (small, 4 gallon maximum capacity), the small intestine (approximately 70 feet), the cecum ( a large digestion vat shaped like a giant comma about 4 feet in length), the large colon (about 15 feet in length with multiple bends and turns), and the small colon (the final 10 feet leading to the ground, small in diameter compared to the large intestine). The cellulose found as a major component of grass is poorly digestible and the horse has adapted in two important ways to aid in the breakdown of cellulose to useable nutrients. First, its long length prolongs the time that food stays in the body so there is a longer time to digest it. Also, there is a population of bacteria that live in the digestive tract that help to break down cellulose so the horse can absorb the nutrients. However, because of its adaptation to continuous grazing, the horse is very susceptible to disruptions of digestive function caused by modern day management practices.
While most colic relates to the abdominal cavity, it is important to realize that other factors can play a significant role in causing pain in horses. Colic signs can be broken into intestinal causes of colic, and non-intestinal causes. Some examples of non-intestinal causes are:
· “Tying up” or exertional rhabdomyolisis
· Laminitis or “Founder”
· Ruptured bladder in male foals
· Abortion
· Uterine torsion twist of the uterus in mid to late pregnancy
· Heart Failure
· Urinary stones
Intestinal reasons for abdominal pain can be broken down to four basic groups:
· Distension:
No physical blockage but the digestive tract can’t move material along normally, the distension of the intestine becomes painful, can be rapid and severe or slow and mild.
Examples:
Gas colic
Spasmodic colic
Thromboembolic colic
· Simple obstruction or blockage:
Where material cannot move down the digestive tract due to an obstruction. Usually mild to moderate pain and relatively slow progression.
Examples:
Feed impaction
Ascarid impaction
Enterolith
Sand
Foreign body
Entrapments
· Obstruction or blockage with partial or complete shut off of the blood supply:
Usually see constant and severe pain with rapid development of shock because of intestinal death and subsequent release of toxins and bacteria into the blood stream.
Examples:
Torsions
Twists
Lipomas – Fatty tumors
Epiploic foramen incarceration
Intussusception
· Enteritis / Colitis, or inflammation of the bowel wall:
Causes stasis of the intestine due to inflammation and subsequent distension of the intestine
Examples:
Salmonella diarrhea
Potomac horse fever
Anterior enteritis
Clostridium diarrhea
Gastric ulcers
With a basic understanding of the pathology of colic, one can soon see that determining the specific cause or reason for the pain can be difficult and with the wide range in the severity of specific diseases it becomes apparent why veterinary intervention becomes so important.
My horse has colic, what do I do?!?
First when you notice your horse exhibiting signs of colic, take immediate action. Time is perhaps one of the most critical factors if colic is to be successfully treated. Some cases may resolve without intervention, but the majority require prompt medical care, possibly including emergency surgery. Some recommendations if you suspect your horse is suffering from colic are: (taken from AAEP handout “Colic, Understanding the Digestive Tract and Its Function,” 1994)
1. Remove all food and water.
2. Notify your veterinarian immediately.
3. Be prepared to provide the following specific information:
· Pulse rate
· Respiratory rate (breathing)
· Rectal temperature
· Color of mucous membranes
· Capillary refill time (tested by pressing on gums adjacent to teeth, releasing, then counting the seconds it takes for color to return)
· Behavioral signs, such as pawing, kicking, rolling, depression, etc.
· Digestive noises, or lack of them
· Bowel movements, including color, consistency and frequency
· Any recent changes in management, feeding, or exercise
· Medical history, including deworming and any past episodes of abdominal pain
· Breeding history and pregnancy status if the patient is a mare, and recent breeding history if the patient is a stallion
· Insurance status and value of the horse (NOTE: The insurance carrier should be notified if surgery or euthanasia is being considered).
4. Keep horse as calm and comfortable as possible. Allow the animal to lie down if it appears to be resting and is not at risk of injury.
5. If the horse is rolling or behaving violently, attempt to walk the horse slowly.
6. Do not administer drugs unless specifically directed to do so by your equine practitioner. Drugs may camouflage problems and interfere with accurate diagnosis.
7. Follow your veterinarian's advice exactly and await his or her arrival.
When the veterinarian arrives, they will try and identify the cause of the colic, evaluate its severity and begin a treatment protocol. Some of the most common procedures are: (taken from AAEP handout “Colic, Understanding the Digestive Tract and Its Function,” 1994)
· Observation of such signs as sweating, abdominal distension (bloating), rapid breathing, flared nostrils, and abnormal behavior
· Obtaining an accurate history
· Passage of a stomach tube to determine presence of excess gas, fluids, and ingesta
· Monitoring vital signs, including temperature, pulse, respiration (TPR), color of the mucous membranes, and capillary refill time
· Rectal palpation for evidence of intestinal blockage, distension, or other abnormalities
· Blood test for white cell count and other data
· Abdominal tap in order to evaluate protein level and cell type in the peritoneal fluid
· Analgesics or sedatives to relieve pain and distress
· Laxatives to help reestablish normal intestinal function
· Continued observation to determine response to treatment
· Transport
If your veterinarian determines that further evaluation and treatment is necessary, they may refer you to a veterinary hospital with advanced diagnostic techniques, and staff who can further evaluate and treat your horse. At a referral hospital, other diagnostic tests such as x-rays (radiographs) of the abdomen, and abdominal ultrasound may be performed to attempt to determine the cause of the abdominal pain. If the pain can be effectively controlled, and there does not seem to be imminent danger to a horse’s life, aggressive medical management including intravenous fluid therapy, analgesics and regular stomach decompression may be initiated in an intensive care unit setting. If the horse does not respond or continues to be exceptionally painful, then surgical intervention may be indicated.
What do you mean surgery?
Surgery may be necessary to save a horses life when severe abdominal pain is present. The number one reason why surgery is pursued is because the pain the horse is encountering cannot be effectively controlled. Other reasons include laboratory or rectal examination abnormalities indicating a surgical disease (enteroliths, severe intestinal gas distension, uterine torsion, failure to respond to other therapies). When this occurs, it is necessary to perform an exploratory abdominal surgery to determine the cause of the problem, evaluate the prognosis for survival, and then if possible fix the problem.
Surgical intervention is a significant undertaking and requires a significant commitment by the owner, both mentally and fiscally. There are risks involved with surgery that go beyond just the original abdominal problem. General anesthesia, and recovery from anesthesia pose potential problems in horses given their size, flight mentality and severe compromise due the primary abdominal problem. Once surgery has been successfully completed, risks of recovery such as catastrophic fracture of a leg pose a threat to a successful outcome. Fortunately, advances in anesthesia have reduced the incidence of such problems significantly, but they have not been eliminated.
Once recovered from surgery, the horse will be admitted to an intensive care unit, where continued care is provided. Intravenous fluids, systemic antibiotics, analgesic and anti-inflammatory medications may be necessary for varying amounts of time depending on the diagnosis. Possible post-operative complications include:
· Endotoxic shock
· Infection within the abdomen (peritonitis) or incision
· Adhesions between intestines causing recurrent colic problems
· Hernia of the abdominal wall
· Diarrhea from bowel damage or gut flora upset
· Salmonella infections – a serious cause of diarrhea
· Laminitis or founder
· Jugular vein thrombosis or blockage (occurs in very sick horses with IV catheters)
Once discharged from the hospital, recovery from major abdominal surgery typically takes 3 months. Initially the horse will be confined to a stall with daily hand walking for 30 days. This will be increased to a small paddock for 30 days, then a larger paddock or small pasture for an additional 30 days before evaluation for return to work. It is necessary to monitor the incision for any swelling or drainage, and typically skin staples will need to be removed about 14 days after surgery. The feeding routine is slowly increased over about 1 weeks time, and access to fresh water is always encouraged.
Luckily for the horse owner, the need for colic surgery is relatively rare. Studies indicate that approximately 10% of all horses are affected by some sort of colic. Eighty percent of cases are termed simple colic, indicating that they resolve with intervention at the farm without aggressive medical or surgical treatments.1 Studies of colic cases diagnosed in veterinary practices also have shown a predominance of simple obstruction or spasmodic colic cases. Often no diagnosis is made in that type of case where signs are easily treated or are mild and transient. Impaction of the colon is the second-most-frequent diagnosis in horse populations or veterinary practices. Colic caused by disease and requiring surgery is rare, only 1%-3% of all horses with colic require surgical intervention.2,3
In a normal farm population, horse mortality from all types of colic was 7 deaths per 1,000 horses over a one-year period of time.1 This is nearly twice as high as other diseases, including traumatic injuries. Of all horses with colic in this farm population, 6.7% died. Most of the fatal cases were due to stomach rupture, strangulated intestine, or enteritis.
|
Percent of resident horses six months of age or older that were affected with the following conditions during 1997 by region |
|||||
|
Cause |
Southern |
Northeast |
Western |
Central |
All |
|
Colic |
4.7 |
5.1 |
4.4 |
4.2 |
4.6 |
From NAHMS Equine ’98 Study, www.aphis.usda.gov/vs/ceah/cahm.
Simple obstructions of the large colon, such as impaction, have a low fatality rate (less than 10%), whereas simple obstructions or impactions of the small intestine are somewhat higher (30%). Impactions of the cecum have a higher fatality rate than impactions of the large colon, but overall, the survival is relatively high (85%). Small intestinal volvulus (twist), incarcerations in mesenteric rents (hernias in the attachments of the intestine) and the epiploic foramen (anatomical internal potential hole) have the highest fatality rate (50-75%). Diseases that cause strangulation obstruction have the highest fatality rate. Of those causing death, large colon volvulus (torsion) is the most common with small intestinal strangulation the next highest.4
These fatality rates appear to be decreasing with the advent of more advanced therapeutic, surgical and anesthetic techniques. Also playing a significant role in improved survival rates is early recognition and intervention by owners and their veterinarians. It is not unusual to have 80%-90% of horses having abdominal surgery discharged from the hospital.4 Long-term survival of horses having abdominal surgery indicates a fatality rate varying from 45.5% to 66%, with evidence of an overall increase in long-term survival in the last 10-15 years. The fatality rate for horses after discharge from the hospital (25%) appears to be improving as well. Of those horses surviving surgery for the long term, most (90%) are able to return to their original function.4
At Alamo Pintado Equine Medical Center, one of the most common causes of colic and need for colic surgery in horses are enteroliths. Enteroliths are concretions of minerals that form into stones in the large colon of horses. In a recent study performed at U.C. Davis, 15.1% of all horses admitted for colic had enteroliths and 27.5% of horses requiring surgery were for enterolith removal.5 Short term (recovered from anesthesia) and 1 year survival rates were 96.2% and 92.5% respectively.5
The overall cost of surgery at Alamo Pintado Equine Medical Center varies depending on the severity of the disease, duration of hospitalization and amount of care required. Typical estimates range from $5000.00 to $8000.00. Horses with uncomplicated enterolith removal average approximately $5000.00 and horses with complicated small intestinal resections are prone to bills in excess of $8000.00.
What can I do to prevent this?
Prevention has always been considered the best method to avoid the problems associated with colic. While horses seem predisposed to colic due to the anatomy and function of their digestive tracts, management can play a key role in prevention. Although not every case is avoidable, the following guidelines can maximize the horse's health and reduce the risk of colic: (taken from AAEP handout “Colic, Understanding the Digestive Tract and Its Function,” 1994)
Summary:
Virtually any horse is susceptible to colic. However, with conscientious care and management, the potential is present to reduce and control the incidence of colic. With the continual improvement in surgical and anesthetic techniques, the survival rate of horse requiring colic surgery is improving.
References:
1.Tinker, M.K., White, N.A., Lessard, P., Thatcher, C.D., Pelzer, K.D., Davis, B., Carmel, D.K. Prospective Study of Equine Colic Incidence and Mortality. Equine Vet J. 1997; 29:448-453.
2. Uhlinger, C. Investigations into the incidence of field colic. Equine Vet. J. (Suppl
13):16-18, 1992.
3. Reeves, M.J., Salman, M., Smith, G. 1996 Risk factors for equine acute abdominal disease (colic): Results from a multi-center case-control study. Preventive Vet. Med. 26:285-301.
4. White, N.A., The Epidemiology of Colic. The Horse 16:8 20-26
5. Hassel, D.M., Langer D.L., Snyder, J.R., et al. Evaluation of enterolithiasis in equids: 900 cases (1974-1996). J Am Vet Med Assoc. 214:233-237