Why the Need?
Both the World Small Animal Veterinary Association and the American Animal Hospital Association recommend recording both a Body Condition Score (BCS), and a Muscle Condition Score (MCS) as part of routine examination data collection.
Although both the BCS and the MCS evaluate uniform muscle wasting due to disease or malnutrition, neither system evaluates whether or not patients have increased muscle mass, or when different parts of the body have different MCS scores. Further, neither system allows for reporting muscle tone, which is easily determined when palpating the patient’s muscle mass.
How Does the MMAT Score Work?
The MMAT score is divided into 3 parts, one for each the hindlimbs, the vertebral
column, and the forelimbs, and each region is assigned its own score. Scores range
from emaciation at one end, to debilitating excess of either mass or tone at the other.
During your physical examination, palpate each the shoulder region, back musculature, and hindlimb musculature, assigning it a number based on the description in the table below.
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How Does the MMAT Score Work?
For example, a dog with normal muscle tone and an even distribution of muscle mass
throughout the body – enough muscle mass to allow long lease walks and playing in the
park – would receive a score of 4/4/4. A working Malinois with taut, strong, and robust
musculature would receive a score of 5/5/5. A dog with chronic bilateral cruciate
disease, with atrophy of the hind legs but over developed musculature in the front legs
due to weight shifting, would receive a score of 5/4/3.
In addition, there may be variations in muscle mass or tone within a body region. For
example, a dog with unilateral cruciate disease may score a 3 for one hind leg, but 4 for
the opposite hind leg. For these cases, assign an average score for the overall
musculature in that region, and flag that value with a hashtag (“#”) symbol. Thus, a dog
with normal muscle mass overall, except for atrophy secondary to chronic left hindlimb
cruciate disease would be assigned a score of 4/4/4#. The “#” alerts the reader that a
separate notation about the hind limbs contained in the medical notes.
Similarly, if there is variation in muscle tone within a region, then an asterix (“*”) is
applied. For example, if the dog above had increased tone in the lumbar muscles
secondary to lower back pain, its score would become 4/4*/4#.
How to Palpate for the MMAT Score
To assess muscle mass, have the patient stand squarely and facing forward. Palpate
the hindlimb musculature over the pelvis and thighs, along the top of the back as well as
the abdominal wall, and the shoulder blade musculature.
Muscle tone can be assessed at the same time, noting any changes from when the
patient is standing, compared to lying down.
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Key Areas to Evaluate
Forelimbs:
Shoulder blade musculature (infraspinatus and supraspinatus): How prominent is
the spine of the scapula? A prominent scapular spine, one that can be pinched from the
sides, indicates inadequate mass of the surrounding musculature. Adequate
musculature allows the top of the scapular spine to be felt, but not the sides. Robust or
athletic musculature results in the top of the scapular spine palpable only as the bottom
of a trough surrounded by raised musculature on either side.
Because of the thickness of front limb fascia, most muscles will have a very firm texture
regardless whether the patient is standing or lying down. The triceps should have firm
but not excessive tone when the patient is standing, and relaxed loose tone when the
patient is lying down.
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Vertebral Column and Abdominal Wall:
Dorsal spinus processes (DSP): The tops of the dorsal spinous processes should be
palpable along the midline of the thoracolumbar spine, but it should not be possible to
pinch the DSP from the sides; DSP become more prominent as the surrounding
musculature atrophies. The mammillary processes are bony prominences that are
shorter and immediately adjacent to the DSP. They should not be palpable in dogs with
normal epaxial muscle mass.
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To assess mass, palpate the musculature down the length of the vertebral column, from
the temporalis muscles of the skull to the last lumbar vertebra. Regions with focal pain
or pathology may have focal atrophy.
Palpate both the epaxial muscles and the abdominal wall to assess tone. Epaxial
muscles are firm due to overlying fascia, but normal tone also allows for full flexibility of
the vertebral column. The abdominal wall should be firm and tucked upward, not soft
and pendulous.
Hindlimbs and Pelvis:
Pelvis and thigh musculature: The cranial aspect of the ilial wings (hip bones) should
be surrounded by musculature that prevents palpation of more than the edge of the
ilium. If the concave aspect of the lateral ilium is palpable, there is a deficiency of gluteal
muscle. Similarly, palpate the circumference of the thigh musculature, noting
development of the quadriceps cranially, and the hamstring muscles caudally.
All pelvic and thigh muscles should feel engaged when standing but relaxed when lying
down or offloading the leg being examined. No spasticity or fibrous tone should be
appreciated.
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Visual descriptions of MMAT scores for each region can be found below:
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