Abstract
Background:
Middle cranial fossa syndrome refers to a group of neurological signs caused by damage to the oculomotor, trochlear, abducent, and trigeminal nerves and sympathetic innervation to the eye as they cross the middle cranial fossa due to different pathologies. Neurological deficits include external ophthalmoparesis or ophthalmoplegia, ptosis, reduced or absent direct and indirect pupillary light reflex, mydriasis, and reduced or absent corneal and nasal sensation. Neoplasia is the most common etiology in dogs and cats.
Canine leishmaniosis is a vector-borne infectious disease caused by Leishmania spp., which has been shown to affect several organs. Although rare, cases of damage to the central and peripheral nervous systems have been reported; however, no cases with signs of middle cranial fossa syndrome have been described.

Case description:
A 16-month-old male neutered 1.5 kg cross breed dog was presented for evaluation with neurological signs consistent with a multifocal neuroanatomical localization (middle cranial fossa, optic chiasm, and cervical and thoracolumbar spinal cord). Laboratory tests revealed hematological and biochemical abnormalities compatible with an infectious process. Computed tomography revealed osteolytic lesions of the basisphenoid bone at the middle cranial fossa and several vertebrae. Cytological analysis of the vertebral lesions identified Leishmania spp. amastigotes Treatment with meglumine antimoniate, allopurinol, and prednisone resulted in rapid clinical and radiological improvement.

Conclusion:
Leishmaniasis is a new potential etiology for middle cranial fossa syndrome in dogs.

Key words: Dog; Leishmania; Middle cranial fossa syndrome.