Development of two surgical approaches to the pituitary gland in the Horse

Abstract

Background: Current treatment of equine pituitary pars intermedia dysfunction (PPID) requires daily oral medication. Minimally invasive surgical palliation of this condition is appealing as a single treatment to alleviate the clinical signs of disease, dramatically improving the welfare of the horse. Objective: To develop a surgical approach to the equine pituitary gland, for subsequent treatment of PPID. Study design: A cadaver study to develop methodology and a terminal procedure under anaesthesia in the most promising techniques. Animals and methods: Four surgical approaches to the pituitary gland were investigated in cadaver animals. A ventral trans-basispheniodal osteotomy and a minimally invasive intravenous approach via the ventral cavernous sinus progressed to live horse trials. Results: Technical complications prevented the myeloscopic and trans-sphenopalatine sinus techniques from being successful. The ventral basisphenoidal osteotomy was repeatable and has potential if an intra-operative imaging guidance system could be employed. The minimally invasive approach was repeatable, atraumatic and relatively inexpensive. Conclusions: A minimally invasive surgical approach to the equine pituitary gland is possible and allows for needle placement within the target tissue. More work is necessary to determine what that treatment might be, but repeatable access to the gland has been obtained, which is a promising step.

A transmandibular lateral transsphenoidal navigated surgical approach to access a pituitary macroadenoma in a warmblood mare

“…Such microsurgical anatomy references are lacking in equine surgery. Previously reported experiences with a series of equine cadaveric specimen trials to access the pituitary gland (Carmalt and Scansen 2018 ) encouraged us to look for alternative approaches. In the latter, the ventral aspect of the basisphenoid bone was accessed through a standard laryngotomy (Ducharme et al.…”

“… 2019 ), intracranial surgery is rarely performed in horses. Apart from a ventral transsphenoidal osteotomy to approach the equine pituitary gland (Carmalt and Scansen 2018 ) there is no available literature as how to access the ventral or ventrolateral aspect of the skull and specifically the pituitary gland in horses. In humans, the treatment of choice for ACTH-dependent hyperadrenocorticism (true Cushing disease) caused by an adenoma is curative by transnasal transsphenoidal hypophysectomy (Biller et al.…”