Before trying home remedies to get rid of a sty on your dog's eyelid, take him to the veterinarian for an examination. It's possible that what you think is a sty could turn out to be a more serious eye condition, such as a tumor.
Formally known as a hordeolum, a sty results from an eyelid gland infection. The most common agent of infection is the bacteria Staphylococcus aureus, and the eyelid glands affected by a sty are called the Glands of Moll and Zeis. A sty is an abscess, which either will form a head and eventually burst or will reabsorb. If it forms a head, don't try to squeeze it; let it burst naturally or via treatment recommended by your vet.
If your dog experiences a sty, this abscess can appear as one or more pimplelike bumps along the margins of the eyelid, often accompanied by eyelid swelling. Styes are painful, so be careful if touching the swelling when examining your pet's eye. Your dog could react with a nip. If the abscess has broken, you might see pus coming out of it.
Because styes resemble other eye infections, your veterinarian must perform a bacterial culture for a definite diagnosis. Other infections or conditions causing eye swelling include bacterial blepharitis, an overall term for eye swelling; a chalazion, or enlarged Meibomian gland, or other Meibomian gland inflammation. In puppies, a swelling resembling a sty can occur with juvenile pyoderma, with small abscesses forming. Older dogs might develop sebaceous adenoma, or oil gland growths on the eyelid. Demodetic mange can also cause eyelid swelling.
Your veterinarian might recommend putting warm compresses on the sty several times a day for five to 15 minutes to bring the infection to a head. She might also prescribe topical antibiotics in the form of eye drops. When the sty bursts, clean the eye of discharge with saline solution. Once the sty heals, the prognosis is good, and it's unlikely to recur. If the sty doesn't heal well or comes back, it's possible your dog was misdiagnosed. Complications can occur when a dog further injures his eye by scratching at the sty.