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Veterinarian Technician March 2013 (Vol 34, No 3)

Equine Essentials: Understanding the Equine Pain Score

by Jamie DeFazio, AS, CVT, VTS (EVN)

    As everyone in the veterinary profession knows, we have one of the greatest challenges in health care: assessing pain in patients that cannot describe the location and level of their pain. Although animals present with signs of pain, sometimes it is difficult to interpret and categorize the signs. Like animals, humans vary in their tolerance of pain; however, people can verbalize their pain score or point to a smiling or frowning face to describe how they feel, whereas veterinary professionals have to assess their patients more creatively.

    In equine medicine, we are paying more attention to pain management and are, therefore, tracking certain metrics and behaviors that are likely to be linked with pain. In horses, we see variances in pain tolerance among breeds and between the sexes.1 For example, an old Belgian broodmare with severe colon torsion may show very mild signs of colic, whereas a young Thoroughbred colt with an impaction could be violently painful and unresponsive to analgesics.

    To assess a patient’s pain score, it is important to tailor the evaluation criteria to the affected area of the body or the condition, as many signs of pain are different. For example, a patient undergoing an orthopedic repair should be monitored for specific signs that may not be pertinent to patients with colic, ophthalmic issues, or respiratory distress. Currently, the greatest focus of equine pain scoring is on orthopedics, specifically laminitis.

    What is evaluated to determine a pain score?

    In any pain assessment, the heart and respiratory rates are important because an increase in either can indicate pain.1 Evaluation of the appetite is also vital, as painful animals are likely to lose interest in feed.2 An animal’s demeanor can also be a good indicator of the pain level because painful animals are likely to become withdrawn and dull and may appear irritable. However, every animal is different; sometimes animals show signs of significant pain without having an increased heart rate or going off their feed.

    Consistent tracking is an important component of accurate pain assessment, so the associated paperwork should be well defined and easy to understand. If possible, the same personnel should be responsible for tracking every animal’s progress.

    Specific pain assessment criteria for orthopedic cases (e.g., horses with laminitis) include the horse’s location in the stall, the position of the head and ears, the digital pulses, and whether the horse is recumbent. Subtle indicators of pain include weight shifts and hoof lifts per minute. These subtle indicators are part of the pain score system that I use.

    Metrics such as heart and respiratory rates are used to track measurable data. The normal range for the equine heart rate is 28 to 44 bpm, and the average respiratory rate is 8 to 24 breaths/min.3 Heart and respiratory rates above these ranges in resting animals should prompt concern for a patient’s comfort level. These metrics can be used to track comfort level over time and the response to analgesia. Blood pressure has also been used in many cases but may not be the most reliable metric. A baseline must be determined for each patient.

    Whether the patient is recumbent and where it is in the stall are good to monitor because horses tend to be creatures of habit. Any change in their routine could indicate that something is wrong. Likewise, any change in a horse’s behavior and demeanor could indicate a problem, as horses tend to have a fairly consistent temperament. An average horse should be standing much more than lying down; during the latter, lateral recumbency is least likely. Horses are most likely to lie sternally and face the front of the stall. Painful animals usually lie laterally, facing a back wall or corner. Nonpainful horses should have an alert demeanor and be curious about their surroundings. Horses should keep their heads up when standing, move their ears regularly, and be bright, alert, and responsive. Conversely, painful horses are likely to hold their heads low, keep their ears still, and have a dull or disinterested demeanor. Pain may cause horses to become manic (i.e., appear aggressive or mad) or, conversely, to appear sleepy.

    In orthopedic and, especially, laminitis cases, it is important to know whether the patient is favoring a limb, especially the one opposite the limb being treated. Ways to determine whether a limb is being favored include counting the number of hoof lifts or weight shifts per minute. Hoof lifts can be a very subtle, early indicator of a problem. In addition, palpating the digital pulses can detect problems with a specific limb.3 It is important to review the pain assessment data in regard to the analgesic treatment to help determine whether the treatment is appropriate. When you review the assessment over a period of 12, 24, or 48 hours (whatever your practice chooses to do), you should look for trends such as a decrease in heart rate or in weight shifting after analgesic medication was given, which would indicate a positive response to medication. If there is no sign of improvement, the pain management should be reevaluated by the veterinarian. It is also important to note any procedures (e.g., farrier treatments, bandage or cast changes, repeat surgical procedures under anesthesia) that were performed.

    A patient’s appetite can also be useful for assessing pain because painful animals are less likely to eat as readily as those that are comfortable. Healthy horses eat an average meal (approximately 2 lb) of concentrate feed in about 15 to 30 minutes4 and should eat hay, grass, or another type of forage steadily throughout the day. Pain is associated with a decreased appetite for both concentrate feed and hay meals.

    The Modified Obel Lameness Score is an example of an evaluation tool (TABLE 1). This scoring system assesses a horse’s willingness to move around the stall, stand if recumbent, and lift its feet. When prompted, a normal horse should rise, pick up each foot, and be willing to move around the stall, even in a circle. A painful horse may be reluctant to stand, even with significant coaxing; may not be willing to be led around a stall; and may be reluctant to pick up the foot opposite the painful limb to avoid bearing more weight on the painful side.

    In my experience, a scale of 1 through 5 or 10 may also be used to evaluate the overall visual assessment based on the data collected. This type of scale is meant to capture the observer’s generalized opinion. You can define your scale in any way that is logical for your practice. For example, on a scale of 10, “5” could indicate that the patient seems to be content, “2” could mean “quite comfortable,” and “8” could mean “very painful.”

    What is done with the data?

    Data collected from pain assessment sheets should be evaluated by the senior veterinary provider. Every member of the veterinary team can help to score the patient, but the collective data shape the overall pain “picture” of the patient. If the patient seems to show improvement shortly after analgesic medications are administered, this can be considered a positive response to treatment. If the patient still shows signs of pain and its comfort level does not seem to improve despite treatment, the pain management plan should be evaluated and adjusted.

    Some cases of pain may be managed with analgesics such as NSAIDs; in cases involving more intense pain, opioids may be necessary. The pain management regimen should be well thought out to gradually adjust dosages or modify medications as needed. There should be (1) a plan for what to try if the patient does not respond and, equally important, (2) a plan for weaning a patient off of medications that have been effective.

    Conclusion

    Monitoring is one of the most important responsibilities of veterinary technicians. By implementing and using equine pain scoring, which requires little training, veterinary technicians can give the veterinarian a more solid report. Practices can tailor pain scoring to suit their needs and the needs of their patients. Intently monitoring your patients’ pain can strongly convey to your clients that your practice provides a high level of care.

    Ms. DeFazio discloses that she is a consultant for International WIN, Ltd. She is also the Equine Essentials section editor for Veterinary Technician.

    1. Orsini J, Divers T. Management of special problems. In: Manual of Equine Emergencies, Treatment and Procedures. Philadelphia, PA: Saunders; 2003:749, 750.

    2. Kentucky Horse Research, Equinews. Causes of Poor Appetite in Horses. www.equinews.com/article/causes-poor-appetite-horses. Accessed May 23, 2012.

    3. Reeder D, Miller S, Wilfong D, et al, eds. Nursing care. In: AAEVT’s Equine Manual for Veterinary Technicians. Ames, Iowa: Wiley-Blackwell; 2009:268-270.

    4. Geor RJ. American Association of Equine Practitioners. How Horses Digest Feed. www.aaep.org/health_articles_view.php?id=200. November 7, 2002. Accessed September 10, 2012.

    References »

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