We report a new form of muscular dystrophy in cats. Signs of muscle weak-ness and atrophy were first noticed in the pelvic limbs beginning about 5–6months of age in two female cats, one Flame-point Siamese and one DSH.Sensation was preserved and reflexes depressed or absent. The DSH cat alsoshowed dramatic contracture of affected muscles. Serum creatine kinase activitywas elevated (8,000 and 6742 U/L). Titers for FIV, FeLV, and Neospora canis(DSH only) were negative. Over 6–12 months, signs progressed to involve thethoracic limb. Before euthanasia at 13 and 18 months of age, the cats were stillbright and responsive, but unable to stand or walk. The DSH had severe contracture of all muscles in the pelvic limb and could only move the distal pha-langes. The tail and lumbar spine were rigid. She could still move the thoraciclimbs, but had limited range of movement of those limbs, the neck and the jaw.EMG showed minimal abnormalities and nerve conduction velocity was slowed.

Fixed and frozen muscle from both cats were evaluated by standard histological and histochemical stains and enzyme reactions. Dystrophic changes includ-ing marked endomysial fibrosis, myofiber necrosis, variability of fiber size andperimysial lipid accumulation were present in both cats.

Immunohistochemicallabeling showed normal reactivity of the sarcolemmal membrane with antibodiesto the rod domain and carboxy terminus of dystrophin; alpha, beta, gamma anddelta-sarcoglycans; and alpha and beta-dystroglycans. Antibodies against the C-terminus of laminin alpha 2 showed an absence of reactivity in both cats, whilethey reacted strongly with laminin alpha 2 in normal cat muscle.Laminin alpha 2 is deficient in 50% of the human cases of congenital musculardystrophy and in the dy dystrophic mouse. In most human cases and in themouse, mutations are found in the gene for the laminin alpha 2. Laminin alpha2 is a subunit of laminins 2 and 4 (collectively called merosin) which are majorcomponents of the muscle basement membrane. To our knowledge, musculardystrophy with deficiency of laminin alpha 2 has not been previously reportedin domestic animals.