SWEENY

• Sweeny is the condition in which the suprascapular nerve is compressed,crushed as it runs around the front of shoulder blade.
• Sweeny is the result of nerve damage at the front of the shoulder blade.
• Its signs include muscle atropy along the side of the scapula and inability of the shoulder joint.
• Sweeny can develop following a scapular neck fracture or as the result of a direct blow to the front of the shoulder.
• The nerve involved is the suprascapular.
• A surgical procedure for removing part of the scapula over which the nerve courses has been described, aiming to provide optimal conditions for nerve recovery.
• Muscle stimulation, under the guidance of a trained physiotherapist, will help to limit muscle fibrosis and may encourage nerve regeneration.
• The suprascapular nerve runs around the front of the scapular neck on its way to the muscle that overlie the scapula: the supraspinatous and infraspinatous muscles.
• However, this process can take many months and frequently some loss of muscle bulk will remain. 
• Trauma to the nerve,or compression by a bone fragment or surrounding soft tissue swelling can result in the lose of nerve supply to these muscles.
• within a couple of weeks,the muscles atropy because they are no longer stimulated to contract.
• loss of muscle function allows the joint to pop out or partially dislocate to the side when the horse bears weight on the leg.
• Careful assessment of the muscles involved and radiography of the neck and shoulder will aid differentiation.
• Scintigraphy is useful for rapid screening of the proximal limb and cervical and thoracic vertebra for damage that may have an adverse effect on prognosis.

Reference

The Mercks veterinary manual