Surgery and Radiology Section

MUSCLE

• Muscle is evaluated for size, tone and strength. All of the muscles should be systematically palpated starting with the head, extending down the neck and trunk and continuing down each limb.
• Change in muscle size may be apparent from observation as well as from palpation loss of muscle mass (Atrophy) is the most frequent finding.
• Atrophy may indicate lower motor neuron (LMN) disease or disuse. Localized muscle atrophy which usually accompanies LMN disease is an important localizing sign.
• Alteration in muscle tone, either increased or decreased can be detected by palpation and passive manipulation of the limb.
• Increased tone of the extensor muscles, a common finding in upper motor neuron (UMN) disease, manifests as an increased resistance to passive flexion of the limb.
• Muscle strength is difficult to evaluate even in the most co-operative patients.
• Extensor muscles can be evaluated during postural reaction such a hopping, in which the animal must support all of its weight on one limb.
• The Flexor muscles can be evaluated by relative strength of pull during a flexor reflex. Loss of muscle strength is usually a sign of LMN disease.