Extensive intraocular melanoma with secondary glaucoma in a 15-month-old Thoroughbred filly.

A 15-month-old, grey, Thoroughbred filly presented for investigation of a 6-week history of corneal oedema and blepharospasm on the right eye (OD). The filly was otherwise healthy. Following ophthalmic examination, glaucoma on the OD was diagnosed. A space occupying mass within the anterior chamber was documented on transpalpebral ultrasonographic examination. This mass obliterated most of the anterior intraocular structures on the peripheral nasal side (corneal endothelium and drainage angle), leading to secondary glaucoma. After systemic and topical treatment addressing secondary glaucoma, the corneal oedema reduced. The mass was visualised as an irregularly rounded brown structure associated with the iris on the peripheral nasal side of the anterior chamber. Given the filly's signalment, location and appearance of the mass, a tentative diagnosis of intraocular melanoma was made and enucleation was performed. Histopathological evaluation of the globe revealed solid sheets of heavily pigmented melanocytic cells, disrupting the normal ciliary body architecture and extending into the iris and subretinal. The cells were pleomorphic, polyhedral to round with occasional spindle-shaped cells, and contained moderate to large amounts of granular black-brown pigment (melanin). The iridal component expanded into the anterior chamber, with cells directly opposed to Descemet's membrane, with loss of the endothelium and expanding and occluding the filtration angle in this area. The lesion infiltrated locally into the edge of the sclera, but did not extend through the sclera, though occasional perivascular clusters of melanophages were observed within the scleral stroma adjacent to the optic nerve. Diagnosis of a uveal melanocytic neoplasm was confirmed, with characteristics similar to only one reported case . This is a unique case of a rapidly growing, invasive, uveal melanoma in a young horse. Intraocular melanoma should be considered as a differential diagnoses for glaucoma in grey horses, regardless of the age and absence of melanocytic skin lesions.

'First Case of Stiff-Horse Syndrome in United Kingdom'.

Stiff-person syndrome is a well-recognised disease in humans, whilst cases of stiff-horse syndrome (SHS) have been rarely reported in the veterinary medicine literature. SHS is a progressive immunomediated disorder of the central nervous system leading to a disturbance of gamma amino butyric acid transmission at the neuromuscular junction in which antibodies are produced against the enzyme glutamic acid decarboxylase. A 6 year-old Irish Sport Horse was presented for investigation of involuntary violent contraction of hindlimb and back muscles triggered by stress. The diagnosis of SHS was made after elevated anti-glutamic acid decarboxylase antibodies titres were detected in the horse's serum. Administration of oral corticosteroids (prednisolone 0.75 mg/kg bwt) resulted in resolution of the clinical signs. However, reoccurrence of clinical signs was observed after the dose of corticosteroids was reduced or the treatment discontinued. To the best of the authors' knowledge this is the first reported case of SHS in United Kingdom. Considering the potential implications on the horses' welfare, further investigation on SHS pathogenesis and treatment are warranted.

Diffusion of Radiodense Contrast Medium Following Perineural Injection of the Deep Branch of the Lateral Plantar Nerve Using Two Different Techniques in Horses: an In Vivo Study.

OBJECTIVES: This article evaluates and compares the diffusion pattern of radiopaque contrast medium following perineural analgesia of the deep branch of the lateral plantar nerve performed using two different techniques: weight-bearing or flexed. STUDY DESIGN: This was an in vivo experimental study. METHODS: Eight horses were enrolled. Perineural injection of the right and left deep branch lateral plantar nerves was performed with a weight-bearing or flexed technique, using radiopaque contrast medium (iohexol). Radiographic evaluation was performed after 5 (T5), 15 (T15) and 30 (T30) minutes. The diffusion of contrast medium was assessed independently by two blinded readers who analysed the extension of the main contrast medium bulk and the maximum diffusion of contrast medium in both proximal and distal directions. The effect of time and technique employed on contrast medium diffusion was assessed using two-way analysis of variance for repeated measures (p ≤ 0.05). RESULTS: There was no significant difference in the diffusion of the contrast medium between the two techniques at T15. However, at T30 the weight-bearing technique resulted in a significantly increased diffusion in the proximal direction (p = 0.02). In one case, belonging to the weight-bearing group, contrast medium was identified within the tarsal sheath. There was no evidence of contrast medium in the tarsometatarsal joint of any horse, regardless of the technique used. CONCLUSIONS: The two techniques resulted in a similar diffusion at T15. However, the use of a weight-bearing technique resulted in a significant increase in proximal contrast medium diffusion 30 minutes after injection.

An atypical presentation of leiomyosarcoma causing extremity compartment syndrome of the crural region in a Dutch Warmblood mare: a case report.

A 12-year-old Warmblood mare was presented with an acute onset left hindlimb lameness associated with generalised soft tissue swelling of the entire limb and medial saphenous vein (MSV) thrombophlebitis. A presumptive diagnosis of extremity compartment syndrome (ECS) was made. Due to the clinical deterioration, emergency fasciotomy of the crural fascia and biopsy was performed. Histological and immunohistochemical examination of the samples confirmed a diagnosis of leiomyosarcoma likely originating from the tunica media of the MSV. This report is the first to describe an unique combination of ECS and thrombophlebitis associated with a leiomyosarcoma in a horse.