Swellings of the angle of the mandible in 32 horses (1997-2011).

This research paper examined the causes of swellings at the angle of the jaw in horses, using records from an equine hospital. Although a large number of cases presented with these swellings, the cause was only identified in 41% of cases. The majority of these were attributed to trauma, with a small number of cases being caused by diseases like cancer or infection. Many cases of unidentifiable swelling had characteristics suggesting trauma but without sign of fracture.

Scope of the Research

• This paper analyzed records from 1997 to 2011 from the Edinburgh University Equine Hospital.
• A total of 32 horses that were referred due to swellings at the angle of the mandible were studied.

Findings

• Out of the 32 cases, the cause of the swellings was determined in 13 (41%).
• These identified causes included fractures, localized trauma, tumors (neoplasia), inflammation of adjacent salivary gland and masseter muscle.
• The remaining 19 cases (59%) did not have a determined cause, but showed patterns that gave clues to their possible origins.

Patterns in Undiagnosed Cases

• Twelve of the undiagnosed cases had characteristic localized injuries on the ventral aspect of the angle of mandible, which the researchers concluded were likely due to trauma.
• The final seven undiagnosed cases had symptoms of chronic infection but no changes to the mandibular bone. The researchers speculated that these might have been caused by draining lesions in the retro-pharyngeal area.

Conclusions

• The research concluded that the cause of swellings at the angle of the equine mandible are often difficult to identify.
• The researchers believe that most are likely due to traumatic injuries, but the horse’s dense musculo-tendinous structures often prevent fractures.
• The team also found that a small number of cases could be attributed to draining retropharyngeal lesions, which responded poorly to medical treatment but well to surgical intervention.