my prince had that in one eye.. it looked like a popped blood vessel or somethin and u could only see it if he looked to the left, i brought it up at one of his vet visits and the dr said that it could be from him scratching his eyes, his hair irritating his eyes, etc. butr more likely from heat. yep, he said that if i have the heater on too close to him or for long periods of time then it could cause this. since then i lowered his heater and keep it across the room & it all cleared up!