Sarah's Dream Shelties & Collies

Collie Eye Anomaly is an inherited developmental defect affecting the eye, specifically the retina (the light-sensitive tissue at the back of the eye) and the choroid (the underlying layer of blood vessels). This genetic condition causes these structures to develop abnormally before birth. It is primarily seen in herding breeds and is inherited in an autosomal recessive manner.

This genetic condition affects the nervous system by impairing the blood-brain barrier, which normally acts as a protective filter for the brain. Due to a missing transport protein, certain common medications can cross this barrier unchecked and accumulate in the brain. This can lead to severe, life-threatening neurological damage.

The merle coat pattern is caused by an autosomal-dominant mutation in the PMEL gene, which affects pigment-producing cells in the skin, eyes, and inner ears. When a dog inherits two copies of this gene, a condition known as double merle, it disrupts the normal development of these sensory organs. This genetic defect can lead to severe structural abnormalities in both the auditory and visual systems.

Ocular anomalies are a group of congenital malformations, meaning they are present from birth, that affect various structures of the dog's eye such as the retina, lens, or cornea. These developmental defects alter the normal structure of the visual system, potentially impacting how light is focused or how the eye functions. The condition is complex and can range from minor physical irregularities to severe structural changes.