Disorder - Spinal muscular atrophy

Organ Systems Involved
Musculoskeletal

Alternative disorders described within LIDA

Neuroaxonal dystrophy; Myopathy

Presenting Signs

Spinal muscular atrophy is a simple recessive trait. This means that both parents must pass a copy of the gene to a kitten in order for it to inherit the disorder. A reduction in muscle mass (muscle atrophy) occurs because of a loss of nerve cells in the spinal cord. The muscles of the upper (proximal) portion of the hind limbs are usually most severely affected. Clinical signs typically start at 13-17 weeks, with an abnormal way of walking and fine muscle tremors (particularly in the hind limbs) being first noticed. While affected cats are bright and responsive, weakness in all limbs (again, especially the hind limbs) rapidly develops. By five months of age, muscles are noticeably wasted, and affected cats walk with widely-spaced forelimbs and sideways-swaying hind limbs. At rest, the hind feet are often rotated outwards. Shallow, rapid breathing may also be observed.

After approximately eight months, the initial rapid decline in muscle function slows, and symptoms stabilise at various levels. Affected cats can survive for many years with a range of disabilities. For example, some cats may be able to walk on all four limbs at six years of age, while others may develop flaccid paralysis of the hind limbs by 2.5 years of age.

Breeds Affected
Maine Coon


PubMed References
Spinal muscular atrophy

Contributor
Ben Sawtell