According to a site I just found, there could be a number of causes for this problem. Here is what it said: Your pet's red eye may signal a problem requiring treatment from eye drops to emergency surgery. Here's a peek at some of the causes and treatments for red eyes. Conjunctivitis "Conjunctivitis-inflammation of the mucous membranes of the eye-is the most common eye disease of all domestic animals," says Dr. Ralph Hamor, veterinary ophthalmologist at the University of Illinois Veterinary Medicine Teaching Hospital in Urbana. Dogs with allergies and purebred cats are prone to conjunctivitis. The eye reddens because of the increased flow of blood, and you may see swelling of the mucous membranes. Viruses or bacteria may cause conjunctivitis; parasites and allergies are less common causes. Discharge may be clear or contain mucus, depending on severity of the infection. "As a rule of thumb, conjunctivitis itches," explains Dr. Hamor. "Keeping the eye clean and eliminating the cause of the conjunctivitis with appropriate medication are keys to control." Keratitis "Chronic superficial keratitis, also know as degenerative pannus, occurs primarily in German shepherds but occasionally in other breeds," says Dr. Paul Gerding, also a veterinary ophthalmologist at the teaching hospital. "The disease causes pigmentation and superficial blood vessels on the eye. It's not that painful but can decrease vision if left untreated. Keratitis also occurs in chronic cases of keratoconjunctivitis sicca (KCS). KCS occurs when there is not enough moisture in the tear film. A thick, ropy mucous discharge is associated with this common ophthalmic disorder. In chronic cases, the corneal layer of the eye becomes infiltrated with blood vessels, pigmented, and harder because of the long-term irritation. Treatment involves tear stimulants and anti-inflammatories. "Eye ulcers are often associated with keratitis and may require surgical repair," adds Dr. Gerding. Inflammation of the eyelids and cherry eye Eyelids may become inflamed from dermatitis; a bacterial, parasitic, or fungal infection; a metabolic or immune system problem; neoplasia; trauma; or sun damage. Treatment varies by exact diagnosis. "Cherry eye" is a prolapse of the gland of the third eyelid. It commonly affects young dogs, especially beagles, cocker spaniels, Pekingese, and bulldogs. "The gland protrudes and becomes irritated and inflamed," explains Dr. Hamor. "If one eye has cherry eye, the other eye could be predisposed to it as well." Treatment for cherry eye is surgical replacement of the gland. Scleritis "Scleritis usually involves only one eye. The red area may develop suddenly and be lumpy, immovable, and hard," says Dr. Gerding. It is often treated with steroids. Uveitis "Inflammation of part or all of the uveal tract is a very common ocular problem in domestic animals and human beings," says Dr. Hamor. The uvea surrounds much of the eye with blood vessels. Your pet may show signs of eye pain such as an overflow of tears, eyelid spasms, sensitivity to light, recession of the eyeball into the orbit, and small pupils. If untreated uveitis harms vision. Glaucoma "Glaucoma, if not treated immediately, can lead to irreversible blindness. A dog with glaucoma deserves the same emergency status as a dog that has been hit by a car," says Dr. Hamor. "Veterinarians may see glaucoma in 8 percent of all canine patients." Glaucoma is an elevation of pressure in the eyeball because an obstruction prevents fluids in the eye from flowing out. Signs of glaucoma include cloudy pupils, large pupils, and redness. "Treatment of acute glaucoma by the primary care veterinarian should be directed toward one goal-rapid reduction of pressure in the eye before permanent blindness occurs. Medical therapy must be started immediately after diagnosis in order to preserve vision," says Dr. Hamor. Blood in the anterior chamber of the eye Bleeding in the eye generally results from trauma, inflammation, or other vascular defects. Hemorrhage from trauma may need to be surgically corrected. Uveitis and neoplasia can bring about growth of new blood vessels, which are inherently leaky and may cause blood to accumulate. If the eye has progressed to glaucoma, removal of the eye may be necessary. For further information about a suspected eye problem in your pet, contact your local veterinarian. http://www.cvm.uiuc.edu/petcolumns/showarticle.cfm?id=65

Dogs can get eye infections including pink eye. They also have very sensitive skin and eyes and noses. Dogs do have allergic reactions and hay fever. If the eyes emit any discharge that looks pussy or are very teary, take the poor pup to the vet. If the dog seems to be rubbing the eyes a lot, bring him to the vet as well because he's adding to the irritation.

You didn't mention what breed your dog is. That can be relative as some breeds are prone to having red eyes in a general way! (Bloodhounds and Bassets both come to mind). This is the season where people are starting to use lawn care products that are NOT exactly friendly to man or beast too. Your dog may have been exposed to something in this arena that has caused some inflammation. Also, depending upon where you live, allergy season is starting to gear up with lots of pollen. Dogs, just like people can suffer from pollen allergies that will cause their eyes to redden and often to swell in addition to redness of the skin (belly most often). If it doesn't clear up (and the dog is not in distress or dismay over it) give it two days to clear. I would strongly say have your vet at least look at it, especially if it just popped up out of nowhere, and the dog has never had it before. Rack your brain a bit too...think of the things your dog may have come into contact with...lawn care products, house cleaning products? If nothing comes to mind at all...do call the vet. Here is a product that works well, I was turned on to it by a client of mine. http://www.petwellbeing.com/dog-conjunctivitis-p31.cfm REMEMBER THOUGH...YOU NEED TO KNOW WHAT THE PROBLEM IS...BEFORE YOU GO USING ANY PRODUCT ON YOUR DOG...neither YOU, ME or anyone here can see your dog, run tests or accurately diagnose what the EXACT problem is.

Allergies. Get some Benadryl and give 1/2mg per lb. every 8 hours (max dose 2mg per lb.) If that helps the redness then you need to experiment with your dog's environment and see if you can figure out what's irritating him. If it doesn't clear up however then go to the vet because he has an eye problem.