[Lafora disease (progressive myoclonic epilepsy) in the Bassett hound--possibility of early diagnosis using muscle biopsy?].

A progressive, hereditary disease has been observed in Basset Hounds, which appears clinically and neuromorphologically as myoclonus epilepsy (ME) and is similar to Lafora-Glueck disease in humans. The characteristic intracellular accumulations are typical myoclonus inclusion bodies. Four forms of inclusion bodies (IB) can be distinguished: a) very small, homogeneous, PAS-positive IBs, b) IBs consisting of an accumulation of PAS-positive particles, c) IBs with a concentric internal structure and a smooth or radial outer zone, and d) IBs with a homogeneous center, concentric layering, light intermediate zone, and a smooth outer zone. The occurrence of IBs is restricted largely to nerve cells. Here they are located mainly in pericarya, to a lesser extent in dendrites, and rarely in the neurites of the peripheral nervous system. IBs are also found in samples of skeletal muscle where they lie between myofibrils or beneath the sarcolemma. They are slightly basophilic in HE-staining and markedly PAS-positive. In transmission electron micrographs IBs prove to consist of chain-like filamentous material of varying density with focal concentrations. They are similar to IBs of the brain. Both muscular and neuronal IBs lack surrounding membranes. Diagnosis of Lafora disease in dogs by examination of muscle biopsies is discussed.