Is it abdominal pain or something else?

Discover your horse restless, pawing, and lying down repeatedly in his stall, and you might immediately think, “He’s colicking.”

Nine times out of 10, you’re probably right. But it’s important to understand that many, many other conditions besides colic can cause coliclike signs. And as with colic, delayed treatment or misdiagnosis can have serious consequences.

“For many of these conditions, if you were to inadvertently take a horse to (exploratory colic) surgery, you might very well might make the animal worse, not to mention spend a lot of money unnecessarily,” says Barbara Dallap Schaer, VMD, Dipl. ACVS, ACVECC, professor of emergency medicine and critical care, associate dean for clinical education and operations for New Bolton Center, and medical director at the University of Pennsylvania School of Veterinary Medicine, in Kennett Square.

Veterinarians define colic as abdominal pain or discomfort—something she says is critical for owners to understand. The classic signs of a horse with colic are many, including:

• Flank-watching or -biting;
• Stretching out;
• Lying down, rolling, or thrashing;
• Decreased appetite or anorexia;
• Weight-shifting;
• Pawing;
• Depression;
• Anxiety or agitation;
• Circling;
• Stiffness or reluctance to move;
• Straining to urinate or defecate;
• Muscle fasciculations (twitching);
• Sweating; and
• Increased heart and/or respiratory rate.

Conditions affecting a variety of body systems can appear similar to colic, often because the horse is painful somewhere, says Jarred Williams, DVM, PhD, Dipl. ACVS-LA, ACVECC, clinical assistant professor of large animal emergency medicine at the University of Georgia’s College of Veterinary Medicine, in Athens. What types of conditions? “Honestly, anything,” he says.

“If the underlying condition is not gastrointestinal (GI) in origin, a misdiagnosis can be made,” he says. “Treatment for the wrong condition or failing to treat for the correct condition can lead to continued morbidity (illness) or even mortality (death).”

In this article we’ll describe the main colic look-alikes, breaking them down by body system.

Urinary/Kidney Disease

Horses suffering from urinary or kidney problems can develop subtle coliclike signs, such as weakness, anorexia, decreased appetite, stretching out, straining to urinate, and depression. One reason is because the discomfort associated with these conditions usually originates in the body cavity or just outside the abdomen, says Williams.

Such conditions can include:

• Urolithiasis, a kidney or bladder stone that can cause affected horses to stretch out to pee frequently, look at their abdomen repeatedly, have a decreased appetite, lose weight suddenly, and act painful and depressed.
• Ruptured bladder in foals, which can cause signs of lethargy, depression, and straining to urinate.
• Urethral neoplasia, or a growth or tumor in the urethra, through which urine travels, which can cause horses to flank-watch, stretch out, and have difficulty urinating.
• Chronic kidney failure, which can cause lethargy, weight loss, and ventral edema (fluid swelling under the abdomen).
• Pheochromocytoma, a tumor of the adrenal gland in front of the kidneys that can erode blood vessels in that area, causing substantial bleeding and pain around the kidney.

“To rule out urinary/kidney disease, the practitioner should observe urination, evaluate a basic biochemical profile and a urinalysis, perform a rectal examination (noting if the bladder is large), and possibly perform a transabdominal ultrasound or abdominocentesis (puncture of the abdomen, or belly tap),” says Williams.

Other signs to look for that might point toward a urinary problem rather than colic include polyuria (increased ­urination), polydipsia (increased drinking), and chronic weight loss.

“And, like with all other non-GI conditions, you don’t find abnormality associated with the GI tract on ultrasound or rectal examination,” Williams adds.

Liver Disease

“Much like urinary/kidney disease, liver disease may present as colic due to signs of pain or depression,” says Williams.

Specifically, hepatic encephalopathy (altered mentation caused by liver damage) and pain from cholelithiasis (bile stones) can cause coliclike signs, such as anorexia, jaundice, recumbency (lying down), circling, anxiety, pawing, and depression, he says. More rarely, says Dallap Schaer, veterinarians encounter liver lobe torsion, which can look like colic.

To diagnose these conditions your veterinarian must run a full liver profile and perform an ultrasound. This can be difficult, however, for vets handling a case on the farm.

“Sometimes your bloodwork will help you, but there are certainly some GI conditions that can cause elevations of liver enzymes,” says Dallap Schaer. “Probably the thing that helps the most is a liver function test, which measures ammonia, which people may or may not be able to run in the field, and a really good abdominal ultrasound to evaluate the liver.”

Giveaways that your veterinarian might be dealing with hepatic encephalopathy, rather than colic, include unusual signs of altered mentation, head-pressing, somnolence (sleepiness), and even coma, says Williams.

Musculoskeletal Disease

We typically associate musculoskeletal issues with lameness, but some do mimic signs of abdominal pain. For instance, horses with the hoof disease laminitis tend to lie down frequently, shift their weight from side to side, have a decreased appetite, are reluctant to move, and develop muscle fasciculations, says Williams.

Fortunately, your veterinarian can easily identify this condition after examining the horse’s hooves, feeling for a digital pulse in the feet, and taking radiographs.

Exertional rhabdomyolysis (the muscle condition tying-up) is another musculoskeletal condition commonly misconstrued as colic. Affected horses might be stiff, sweaty, anorexic, and reluctant to move; lie down frequently; and have muscle fasciculations, says Williams.

Your veterinarian can diagnose tying-up based on muscle palpation and measuring serum creatine kinase (an enzyme associated with muscle damage) levels. “Rapid and accurate diagnosis of rhabdomyolysis is essential” to a horse’s prognosis, he adds, so owners should be aware of this disease and call a veterinarian immediately if they see signs of it.

Dallap Schaer recalls one case in which an owner walked her tying-up Quarter Horse for 14 hours, thinking he was colicking (owners have historically been told to walk horses with colic, mainly to prevent them from rolling, thrashing, and injuring themselves). He ended up dying of kidney failure.

“It is really important for clients to understand that walking is going to make certain conditions like rhabdomyolysis worse,” she says. “The same goes for laminitis or botulism.”

Other musculoskeletal conditions that can mimic colic include:

• Clostridial myositis, or muscle inflammation, with signs of flank-watching, pain, and reluctance to move. This potentially fatal disease is often associated with intramuscular (IM) Banamine (flunixin meglumine) injections. “This is why it’s important for vets first looking at the horse to get accurate information from the owner, like did he get IM Banamine?” says Dallap Schaer. “Then understand the timeliness of that disease, because it’s one that if you don’t catch onto it right away can really progress fast.”
• Hyperkalemic periodic paralysis, a genetic disorder that causes weakness, stiffness, recumbency, circling, and anorexia; and
• Pelvic fracture.

“I have had horses present for colic with foot abscesses,” says Williams. “The bottom line is a painful horse that doesn’t want to eat and/or move and spends time lying down may be mistaken for colic.”

Respiratory Disease

The main respiratory issues veterinarians misdiagnose as colic, says Williams, are those associated with pleural (lung lining) pain. Specifically, pleuropneumonia (pneumonia complicated with pleurisy and sepsis, a systemic inflammation) can cause rapid breathing, depression, anorexia, flank-watching, and reluctance to move, he says. Rib fractures (which occur primarily in foals) can cause similar signs.

Your veterinarian can palpate for rib pain and take radiographs. He or she might also hear a clicking noise when listening to the rib area with a stethoscope.

To diagnose pleuropneumonia your veterinarian can perform ultrasound or thoracocentesis (a chest tap) and listen to lung sounds. With the stethoscope, he or she might be able to hear heart sounds radiating across several rib spaces, due to fluid in the affected horse’s chest, says Dallap Schaer.

She adds that horses with pleuropneumonia also display a very characteristic stance. “They stand with their elbows abducted (held away from the body), and they classically hate turning tightly in a stall,” she says. “So that should alert you to the fact you have pleural pain rather than GI disease.”

Two other respiratory-related issues that might manifest as colic include diaphragmatic hernias and pulmonary neoplasias.

While some signs of respiratory and gastrointestinal disease are subtle and overlap, “horses with respiratory disease tend to have a more sustained tachypnea (increased respiratory rate) and/or labored or trouble breathing,” says Williams. “Oftentimes the diagnosis of respiratory versus gastrointestinal has a lot to do with the veterinarian’s suspicion of disease, coupled with exclusion of the nonoffending system (i.e., the GI tract).”

Neurologic Disease

Horses that are ataxic (incoordinated), staggering, or recumbent due to neurologic disease can also appear as if they’re colicking. Causes might include:

• Rabies;
• Tetanus;
• Equine motor neuron disease, a neurodegenerative disease that in its early stages causes weakness, weightshifting from side to side, sweating, recumbency, muscle fasciculations, and weight loss. “EMND horses have a really characteristic stance, like they’re an elephant standing on a ball, and they tend to not be persistently painful,” notes Dallap Schaer; and
• Botulism, a deadly disease caused by Clostridium botulinum toxins, which can be challenging to differentiate from colic in its early stages, says Williams. Signs include recumbency, dysphagia (inability to swallow), anorexia, muscle fasciculations, tachycardia (increased heart rate), and dullness. “With time, the patient will progress to signs more consistent with botulism than colic,” he says.

“Botulism is far and away the biggest colic imitator we see up here,” says Dallap Schaer. “If you inadvertently take a horse with botulism to surgery, you’re probably sealing its fate.”

She says one indicator a horse has botulism and not colic is that his high heart rate often drops as soon as he becomes recumbent, and typically he won’t roll. These horses also lose their ability to grasp grain and hay readily and efficiently due to reduced tongue strength.

“In the absence of other colic signs, the inability to rise or altered mentation may differentiate neurologic disease from gastrointestinal,” says Williams.

When examining these animals, says Dallap Schaer, veterinarians should get a thorough history of the horse’s ­vaccination status against diseases such as rabies and botulism.

Reproductive Problems

Both stallions and mares can demonstrate reproductive-system-related colic signs simply due to these organs’ proximity to the abdomen.

Testicular torsion, inguinal hernia, or neoplasia can cause stallions to flank-watch, stretch out, paw, roll, and lie down. Your veterinarian can easily diagnose these issues, however, by palpating and using ultrasound to scan the testicles.

The condition most commonly confused with colic in mares? Ovulation, says Williams, thanks to general ovary discomfort. Mares might flank-watch, paw, lie down frequently, roll, and act irritable. Other things that can cause mares to display coliclike signs include:

• Pneumovagina (aspiration of air into the vulva, or “wind sucking”);
• Uterine artery bleed and hemoabdomen (blood in the ­abdomen);
• Ovarian tumors; and
• Uterine torsion.

For the latter three, veterinarians can palpate the ovaries and perform transrectal ultrasound to rule these conditions in or out, says Williams. For pneumovagina, “palpate and give them a dose of oxytocin (which causes the uterus to contract), and they’re fixed,” says Dallap Schaer.

Drugs and Toxins

Horses occasionally have adverse reactions to plants (e.g., red maple, jimsonweed) and medications (e.g., antibiotics such as penicillin or ceftiofur) that manifest as colic signs. Some are also sensitive to the antipsychotic fluphenazine, sometimes used as a long-term tranquilizer.

“The colic signs (during a fluphenazine reaction) are typically lying down, rolling, and oftentimes thrashing around the stall uncontrollably,” says Williams. “A characteristic stance with the head bowed between the legs and a careful interview with the responsible parties help to make the diagnosis.”

Horses that have ingested jimsonweed, says Dallap Schaer, have dilated pupils, while those with red maple poisoning experience red blood cell destruction that causes them to have chocolate-colored mucous membranes (gums).

… And Almost Anything Else

Myriad conditions can confuse owners into thinking their horses have body cavity pain caused by the GI tract. Knowing it could be something besides colic and making that call to the vet as soon as possible can help your horse have a positive prognosis, says Dallap Schaer.

“Even the most experienced person can be fooled,” says Williams. “Your best opportunity to get it correct is to have a veterinarian evaluate the horse and, even then, more specialized veterinarians may be needed. My advice is to never just assume. Many problems can snowball into bigger problems quickly.” 

Lastly, says Dallap Schaer, note all the signs your horse displays and what you observed first. As the owner, you can play a critical role in providing your veterinarian with the history, signs, and vaccination status he or she needs to diagnose and treat your horse properly.