Arthroscopic approach to the subextensorius recess of the lateral femorotibial joint of the foal.

OBJECTIVE: To (1) develop an arthroscopic approach to the subextensorius recess of the lateral femorotibial (LFT) joint in foals and (2) report its use in foals with LFT joint sepsis. STUDY DESIGN: (1) Anatomic study and (2) retrospective case series. SAMPLE POPULATION: (1) Cadaveric hind limbs (n = 32 foals) to delineate the anatomy of the subextensorius recess; 13 foal limbs for cadaver surgery to assess the approach to the subextensorius recess; and (2) foals (n = 8) with LFT joint sepsis. METHODS: (1) The LFT joint was distended and examined ultrasonographically. Dissection was used to document periarticular landmarks, potential distal arthroscopic portals, and assess iatrogenic damage after cadaveric surgery. (2) Retrieval of data from 8 foals with LFT joint sepsis treated using the arthroscopic approach. RESULTS: (1) The optimal arthroscopic approach to the distal subextensorius recess is craniolaterally, 8-10 cm distal to the tibial plateau, immediately caudal to the peroneus tertius muscle, through the long digital extensor muscle belly, entering the distal extent of the subextensorius recess. Thirteen limbs dissected after cadaver surgery had no iatrogenic damage to the peroneus tertius muscle or peroneal nerve. (2) Two foals were euthanized. Resolution of sepsis occurred in 6 foals, and all were sound at follow-up >9 months after surgery. CONCLUSION: The subextensorius recess may be safely accessed arthroscopically in foals.

Hypertrichosis in a horse with alimentary T-cell lymphoma and pituitary involvement.

A 13-year-old Quarterhorse mare had a 6-month history of diarrhea, progressive weight loss, and lethargy. At presentation the mare was hirsute, had hyperhidrosis, and abnormal fat distribution in addition to severe diarrhea. A presumptive clinical diagnosis of protein-losing enteropathy and pituitary pars intermedia dysfunction was made. T-cell lymphoma was diagnosed in a rectal biopsy specimen. The owner elected to euthanize the mare because of poor prognosis and the severity of the disease. At necropsy, the mare had hypertrichosis and the pituitary gland was diffusely enlarged. Histologically, neoplastic lymphocytes infiltrated the gastrointestinal mucosa, mesenteric lymph nodes, and the pituitary gland. In addition, there was hyperplasia of the pituitary gland pars intermedia. Pituitary adenoma was not present. Hypertrichosis in this case could have been triggered by a combination of adenomatous hyperplasia of pars intermedia and lymphoma resulting in disruption of the hypothalamic dopaminergic tone or disruption of the hypothalamic thermoregulatory center.