Guttural pouch mycosis in six horses in New Zealand.

The research highlights six cases of guttural pouch mycosis, a fungal infection, in horses of New Zealand and discusses their diagnosis, treatment, and outcomes, making this the first documented report of this type of equine disease in New Zealand.

Case Presentations

• Six horses from different locations in New Zealand exhibited symptoms of guttural pouch mycosis, a fungal infection of the guttural pouch, a sac-like structure in the horse’s head. Notably, all horses had a history of nose bleed (epistaxis) within two weeks before being diagnosed.
• Five out of the six horses were diagnosed with guttural pouch mycosis based on endoscopic examination, a procedure using an instrument that allows visual examination of interior parts of the body, that revealed fungal plaques inside the affected guttural pouches. However, one horse died before surgical treatment could be attempted.

Treatments and Outcomes

• Out of the remaining four horses, all underwent a surgical procedure of ligation (tying off) and balloon catheter occlusion (blockage) of the internal carotid artery, a major blood vessel supplying the affected pouch.
• Three of these treated horses survived and showed good health a year after the operation.
• One horse had a fatal bleeding episode eight weeks post-surgery.

Additional Cases and Findings

• In the sixth horse, an endoscopy was performed, but the recently bleeding guttural pouch wasn’t accessed. Though it underwent ligation surgery, it ultimately died. The post-mortem examination revealed a guttural pouch mycosis infection of the maxillary artery, another blood vessel inside the guttural pouch – confirming the disease was indeed guttural pouch mycosis.
• Further microscopic examination (histology) showed the presence of fungal structures (hyphae) in the blood clots in the interior (lumen) of the affected maxillary artery within the infected guttural pouch.
• Also, two horses showed symptoms indicative of damage to the cranial nerve, a collection of nerves in the head, within the guttural pouch.

Significance and Implications

• The study serves as the first documented record of clinical cases of guttural pouch mycosis in horses in New Zealand.
• Veterinary practitioners in New Zealand need to recognise this disease’s signs to ensure timely treatment or referral for surgical intervention, thus avoiding fatal bleeding or serious neurological symptoms.