Neuronal lipofuscinosis in an adult horse

Lipofuscin pigment can accumulate in different post mitotic cells especially neurons and glial cells. This pigment induces cellular dysfunction and degeneration in the affected cells and produces neurologic disorders. An adult (12 years old) cross bred female horse with clinical signs including progressive weight loss, salivation, dysphagia and some neurologic symptoms including incoordination, repeating chewing behavior and severe depression was referred to the Hospital of Veterinary faculty of Tehran University. Because the horse did not show any progression in treatment, it was euthanized. At necropsy, none of the organs had any gross lesions except brain. The brain tissue showed softness in palpation without any gross discoloration. However, microscopically there were perinuclear eosinophilic, autofluorescent lipofuscin pigments in the nerve cells of cerebrum and cerebellum. The pigments were positive in Periodic Acid Shift (PAS) staining method. In the cerebrum there were vacuolation of white matter, axonal degeneration and loss of myelin. Histopathological investigation suggested the neuronal lipofuscinosis in the horse.