The Long Reach of Pain

As prey animals, horses naturally hide signs of pain, because showing pain could make them more vulnerable to predators. This instinct makes it difficult for us to pick up on a horse’s discomfort until the severity is quite advanced.? Being aware of even subtle changes in your horse’s movement, personality and habits can make all the difference in how quickly you detect pain in your horse.

WHAT IS PAIN’ Pain is multifaceted. Its varying degrees and types are influenced by hundreds of chemical signals that vary widely. Driven by the nervous system, pain is complex and bodywide. Think about it this way: Stepping on a nail is a split-second occurrence, but in that split-second the body uses hundreds of chemical transmitters to achieve what we call ?pain.?

TYPES OF PAIN. Pain can be either acute (instant) or chronic (ongoing).? It can be described by the body system affected (i.e. musculoskeletal or visceral) or the area of the body, such as abdominal.? For instance: Acute abdominal pain,? that nasty phenomenon commonly known as colic, is a visceral pain.

Although tHere’s a lot of controversy as to how to classify the many types of pain, We’ve zeroed in on the four we find most common:?

1. Pain due to a noxious stimulus. A noxious stimulus is the nail the horse steps on. It can also be a pressure point from an ill-fitting saddle. In many instances, this pain is acute and occurs as a result of a foreign object or action that impacts the body. it’s anything that creates an instant feeling of discomfort.

2. Pain due to inflammation. Inflammation is a complex physiologic phenomenon that is commonly characterized by five cardinal signs: Heat, Swelling, Redness, Loss of Use, and Pain.? Inflammation occurs when the body experiences a harmful stimulus, such as a difficult workout that results in sore, fatigued muscles. Inflammation is a protective attempt by the body to stop the injurious stimuli and to initiate the healing process.? Without it, we couldn?t heal.

Inflammation increases blood circulation to the injured tissue to bring oxygen and inflammatory cells to begin the healing process. Inflammation?s pain reminds the body not to use the hurt area so that it may heal sufficiently.

3. Pain due to infection. Infection is defined as the invasion of body tissues by a disease-causing organism.? Nine times out of 10, it’s bacteria, but it could also be a virus (West Nile encephalitis or influenza), fungus (thrush, canker), protozoan (EPM), or parasite (encysted larval small strongyles in the colon wall).?? The body?s defense to infection is inflammation and that, as we know, causes pain.

4. Neurogenic pain. This is often associated with chronic pain. It occurs when a noxious stimulus (such as a pressure point from an ill-fitting saddle) occurs repeatedly over a long period of time. This is by far the most difficult type of pain to detect and manage.

that’s because a body in chronic pain will undergo a series of changes to its pain receptors and to its response to the signals that the chronically damaged tissues send to the brain.? These changes can result in an abnormal, inappropriate pain sensation in the body (also known as parestesia) and are proven to change one?s personality?for the worse!

People in chronic pain are on edge, irritable, and often fatigued.? They have problems sleeping and functioning on a day-to-day basis due to a constant distractive hypersensitivity to stimuli.? Over a long period of time, a body in chronic pain undergoes a serious transformation in its nervous system called ?spinal cord wind-up.?

Spinal cord wind-up is characterized as the upregulation of the NMDA (n-methy-d-aspartate) pain super-receptor.? (Think of the NMDA receptor as one pain receptor that does the work of 10.)? When this receptor is unregulated, the body can become exponentially more sensitive to stimuli, causing those that previously weren?t painful to become painful.? Chronic pain also can cause a sustained release of stress hormones that can cause ulcers, tax the liver, and impaire immune function.

THE MEMORY OF PAIN. Neurogenic pain is a deep and dangerous rabbit hole.? This is because of the multiple physiologic changes the body undergoes as a result of chronic painful stimuli.

Once the body makes the physiologic changes characterized as spinal cord wind-up, they can’t easily be undone.? Posture can change, tendon and ligament elasticity lessens due to decreased range of motion, muscles shrink, and the body suffers.? Often, removing the chronic painful stimulus, like injecting an arthritic joint with cortisone, won?t make everything better.? (Sure, you put out the fire, but all of the land is still scorched!)

Horses walk around every day with neurogenic pain with no ?symptoms.? Over time, the owner starts to see the horse’s behavior or body posture as normal for that horse, even though they’re actually a result of spinal cord wind up.

How many times have we heard, ?Oh, he has always been like that!?’? Well, that may mean that there has always been a problem. Bodies can ?remember? pain and remain irritable for years.? So how do we fix it’

ADDRESSING A HORSE IN PAIN. First, determine if any pain truly exists. Ask yourself these questions:

1. Does my horse have any history of injury’

2. Are there any medical conditions, like arthritis or ulcers, that would cause my horse to be in chronic discomfort’

3. Is my horse spooky or on-edge all the time’

4. Does he show signs of sleep deprivation, such as abraded front fetlocks or drowsiness in cross-ties’

5. Has there been any uncharacteristic change in my horse’s demeanor or behavior (such as irritability or grinding teeth)’

6. Does my horse resist doing certain activities such as walking down hills or taking the rein’

7. Does he seem sore to the touch’

If any of these answers are ?Yes,? ask your veterinarian to guide you through the investigation.? Some veterinarians, especially those who have undergone acupuncture and chiropractic training, can detect subtle sources of pain in horses, helping determine if your horse is ?hiding? a painful condition.

The next step is therapy. If it’s an obvious source of chronic pain, you may be able to quickly put your horse on the road to recovery. For problems that are less obvious, such as gastric ulcers, you may have to pursue diagnostics, such as gastroscopy, to rule them in or out.? Some horse owners put their horses on ulcer medication for two weeks to see if it can make a difference.

Therapies such as acupuncture, acupressure, therapeutic ultrasound, massage and chiropractic help reverse spinal cord wind-up.? Just remember: Be patient.? Problems that have existed for years don’t go away after one treatment.? It can take a long time to reteach a body how to sense stimuli and turn-off the NMDA pain receptors.

Finally, if one or several therapies are working in your horse, be mindful of the changes that you see.? If your horse reverts back to his ?old ways,? it probably means that you need to revisit your management program and determine where a change needs to be made.

don’t forget that medications can be a wonderful help when addressing painful conditions in horses, and We’ve included them in our chart pain meds.? Some of these medications are available over the counter, while others must be prescribed by your veterinarian.

Article by Dr. Grant Miller, Contributing Veterinary Editor.

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