Glaucoma is relatively common in the dog, with a number of potential causes. Canine primary angle-closure glaucoma is a common such cause, with important prognostic and treatment indications for the remaining, fellow eye. Accurate diagnosis is, therefore, critical, and can be hindered by concurrent lesions like uveitis and preiridal membranes. While the pathogenesis of glaucoma development in this disease remains incompletely understood, the underlying lesion is goniodysgenesis (literally, malformed angle). The image to the right is a photomicrograph of a normal canine iridocorneal angle, with a perforated pectinate ligament (*).
In the image below, the asterisk denotes a thick and imperforate pectinate ligament - the lesion of goniodysgenesis. The ciliary cleft is open, and trabecular meshwork are visible, indicating a non-glaucomatous state at this point.
In this image, the thickened pectinate ligament (*) overlies a collapsed ciliary cleft
and inapparent trabecular meshwork (narrow rectangle), consistent with chronic
glaucoma. This dog's other eye is at high risk for primary angle-closure glaucoma.
Dr. Christopher Reilly