There are no laboratory or imaging tests available that can confirm the presence of trigger points or myofascial pain disorders,
although new studies into the identification of taut bands with magnetic resonance elastography are promising.1 MRI examination of veterinary patients is limited to locating taut bands in skeletal muscles, detecting myofascial restrictions
and provoking patient responses to manual pressure. Patient reports of degree of pain and painful referral patterns are not
identifiable in animals. Correlating postural deviations, gait and locomotor abnormalities and functional deficits can aid
in identifying a pattern of dysfunction. Developing a consistent protocol for palpating for the presence of trigger points
and fascial restrictions will enhance the likelihood of locating affected myofascial tissues.
Canine patients likely to develop myofascial pain include athletes or very active dogs, hunting, agility, racing or field
trial dogs, geriatric and osteoarthritic patients, those with traumatic injuries or those with neurologic disease or chronic
neurologic weakness. It is difficult to find hard data on the prevalence of myofascial disorders, but an Australian study
of medical students found that nearly 90% of them had some degree of body pain (primarily in the neck, back and shoulders)
of myofascial origin – and those were young people. According to Dr Janet Travell, "Myofascial trigger points are a frequently
overlooked and misunderstood source of the distressingly ubiquitous musculoskeletal aches and pains of mankind." It is likely
that our patients suffer from a similar degree of pain and dysfunction associated with myofascial dysfunction.
The diagnosis of myofascial pain in the canine is based on a careful history, observation of locomotor and functional mobility
and a thorough and systematic palpation of myofascial tissues. Common owner complaints (none of which are specifically myofascial
in origin) include
- Change or decrease in performance
- Lameness (with no discernible joint, tendon or ligamentous pathology)
- Gait deviations such as short striding, base-narrow gait, not tracking straight
- Decreased endurance
- Sudden unwillingness to perform certain activities such as long leash walks, jumping onto the furniture, etc
- Resentful of being touched or brushed.
- Restlessness or difficulty sleeping
A careful gait and functional locomotor examination should be performed, not only looking for lameness, but also evaluating
the quality of movement. How willing is the animal to move. Is the movement symmetrical and fluid or asynchronous, shortened
and jerky? How does the animal perform on steps, inclines and backing up? Are certain motions restricted in range? Does the
animal have adequate endurance or does it fatigue quickly? Can the animal remain stationary for a period of time or does it
become restless? Any of these activities may be altered by myofascial pain.
The diagnostic hallmark of myofascial dysfunction is abnormal palpation findings. The presence of nodules and taut bands characterize
muscle trigger points. Fascial restrictions will alter tissue texture, resilience and glide. A systematic examination progressing
from superficial to deeper tissues should be performed. The animal needs to be relaxed and warm to differentiate tissue tension
from voluntary muscle tension.
- Assess thickness and mobility of the skin in relation to the subcutaneous tissues.
- Perform "skin rolling" by lifting and rolling a "wave" of skin.
- Assess the thickness and three-dimensional mobility of the subcutaneous fascia.
- Note patient response to compression of tender fascia.
- Place the muscle to be tested under slight tension. Palpate perpendicular to muscle fibers to locate the taut band.
- Palpate along the taut band to locate the nodule and the area of maximum tenderness.
- Roll the trigger point under the fingers to elicit a local twitch response, an involuntary contraction of the muscle as the
taut band is strummed causing a jerk of the body part.
- Apparent tenderness, often reflected by an attempt to bite, is noted.
- Assess the range of motion and flexibility of the affected muscle.
Common trigger points in the canine include but are not limited to: triceps brachii, infraspinatus, latissimus dorsi, peroneus
longus, gluteus medius, iliocostalis lumborum, adductor-pectineus, and quadriceps femoris.2