My 85 lb border collie mix recently started having runny eyes. It started when I noticed the white part of his eyes were slightly pink on the left side. Now goo is appearing every day in the corner of each eye. When I wipe it clean, he starts to rub his eyes on the carpet. It must be itching him. Should I take him to our vet or can I buy something over the counter? If I didn't know better, I'd say he had human pink eye.

Optional Information:
Age: 6; Male; Breed: border collie mix

Already Tried:
nothing