Enzyme histochemistry on muscle biopsies as an aid in the diagnosis of diseases of the equine neuromuscular system: a study of six cases.

This research examines muscle biopsies from six horses with muscle-related symptoms, using enzyme histochemical techniques to aid in diagnosing potential neuromuscular disorders. The study suggests that these techniques can be effective in diagnosing such conditions in horses, revealing similar pathohistochemical changes as those found in the diseased skeletal muscles of humans.

Study Overview

• The focus of this study was on enzyme histochemistry or the use of enzyme-specific stains to analyse the cellular level composition of muscle biopsies from six horses.
• The horses selected for the study displayed symptoms such as muscle tremors, muscle atrophy, myopathic symptoms, unsteadiness of pelvic limbs and progressive ataxia. These symptoms were suggestive of potential neuromuscular disorders.
• The main aim was to evaluate the diagnostic value of enzyme histochemical techniques in identifying neuromuscular disorders in horses.

Findings

• The study found a variety of conditions within the biopsied muscle tissues like hypertrophy, atrophy, fibre splitting, waxy degeneration, phagocytosis and necrosis.
• Using the calcium ion stimulated myosine ATP-ase (Ca-ATP-ase) stain, fibre type predominance and fibre type grouping were observed in some cases.
• Three cases displayed ‘Moth-eaten fibres’ which were identified using various stains such as NADH: nitro blue tetrazolium oxidoreductase (NADH-TR), succinate dehydrogenase (SDH), NADH dependent malate dehydrogenase, cytochrome c oxidase and lactate dehydrogenase.
• In the cases with fibre phagocytosis, catabolic enzymes like acid phosphatase (ACP) and 5′-nucleotidase were active.
• In three cases, an increased activity of glucose-6-phosphate dehydrogenase (GPDH) and 6-phosphogluconate dehydrogenase (PGDH) indicated the importance of the oxidative part of the pentose phosphate pathway in myopathic tissue.

Interpretation and Recommendations

• The study found that the pathological changes in the horse muscle tissue were similar to those observed in diseased skeletal muscles in humans, suggesting a similar pathology process for neuromuscular disorders in both species.
• Based on the findings of the research, the authors recommend the use of tissue-saving enzyme histochemical techniques for studying muscle tissues in horses suspected of having neuromuscular disorders.