Episodic, involuntary muscle contractions or spasms involving the hindlimbs are associated with postural and locomotor disturbances as well as spasticity. The condition may progress to posterior paresis or hindlimb paralysis. It is seen most frequently in Holstein and Guernsey cattle 3–7 yr old. Spastic syndrome is regarded as a genetic disease, possibly due to an autosomal dominant gene with incomplete penetrance. The pathology and pathophysiology remain obscure.
Clinical signs may vary in severity, duration, and frequency. Usually, some stimulus provokes the onset of clinical signs, such as the effort associated with rising or any factor that induces a significant emotional reaction. Pain, particularly in the feet or joints, may precipitate an attack. During an attack, the animal may be unable to move forward, stands trembling, and characteristically extends its hindlimbs backward. Between episodes, the animal can ambulate normally.
Spastic syndrome is progressive, and because of the possibility of genetic transmission, animals (particularly bulls used for artificial insemination) are best eliminated as soon as a positive diagnosis is made. Palliative treatment for animals in the peak of production may be helpful. Mephenesin (30–40 mg/kg, PO, for 2–3 days) may be given during an episode. Phenylbutazone may also have beneficial effects.