Branchial remnant cysts of mature and juvenile horses.

The research article discusses eight cases of branchial remnant cysts (BRC) in horses, observed in both mature horses and foals. It details the presentation, diagnosis, treatment, and potential post-surgery complications of BRC.

Clinical Presentation of Cases

The article reports that horses with BRC came in two age groups: 5 mature horses aged 8 to 21 years old and 3 foals aged 1, 6, and 10 months. Different symptoms were used to identify the BRC:

• Mature horses usually exhibited dysphagia, intermittent obstruction of the oesophagus, and swelling behind the pharynx
• Foals generally exhibited respiratory stridor and visible masses.

On clinical examination, a palpable mass was often found in the retropharyngeal area. These masses ranged in size from 3 to 35 cm in diameter, were usually located on the right side, or positioned dorsally. In one case, a mass was found on the left side during a routine post-mortem examination.

Diagnosis and Histopathology

The diagnosis for BRC used various diagnostic techniques:

• Ultrasonography typically revealed thick-walled cysts filled with hypoechoic fluid, which may have blood clots represented by hyperechoic masses
• Radiographs and upper airway endoscopy also suggested a retropharyngeal mass
• Fluid cytology revealed chronic haemorrhage in six out of eight cases and squamous epithelial cells in one case.

Histopathology, the microscopic examination of tissue to study the manifestations of disease, uniformly showed an epithelium-lined cyst with no smooth muscle or thyroid tissue in all cases.

Case Outcomes and Treatment

Two out of the eight cases resulted in euthanasia, one due to concurrent laryngeal anomalies and the other due to financial limitations. The remaining 5 cases were treated through surgical excision. After surgery, it was noted that four out of the five cases showed right laryngeal hemiplegia, a condition which can lead to swallowing and breathing difficulties.

Implications for Future Research

The paper points out that all prior BRC cases reported in horses focused on juvenile animals, indicating that this study expands the understanding of BRC to include mature horses as potential patients. The research suggests that if a mature horse has a mass in the throatlatch area, the possibility of a BRC should be considered. They also emphasize that surgical treatment may commonly result in right recurrent laryngeal nerve damage, requiring further care and treatment.