What Makes the Whites of Your Dog's Eyes Red?

Foreign Bodies

• If your dog spends any time outside, myriad things can come in contact with your dog's eye, including bushes, bugs, grass or burrs. These types of irritants can create inflammation, which causes the whites of the eyes to become red. Your dog may experience eye pain as evidenced by squinting, tearing or pawing at his eyes. Check your dog's eye or eyes, starting by restraining him and ensuring that he is quiet and calm. Part the eyelids with a clean finger and thumb and look for a foreign body.

  If the foreign body is embedded in or penetrating the eye, do not touch it; instead contact your vet immediately, advises dog expert and author David Taylor. If the foreign body is sitting on the surface of the eye, try to remove it by irrigating the eye with a gentle saline solution -- don't use a cotton swab, though; it can leave tiny fibers that cause more problems.

Episcleritis

• Episcleritis is an inflammation that begins in the white part of the eye and is often thought to be related to a compromised immune system, according to PetMD.com. Dogs with episcleritis exhibit reddening of the sclera and enlarged blood vessels, which can cause the tissue to thicken. Episcleritis is typically contained to one specific area of the eye, but it can spread to other portions if left untreated. It may be difficult to detect episcleritis from conjunctivitis or glaucoma, so it is not a condition you can treat at home. The vet may prescribe anti-inflammatory drugs -- if there is no secondary corneal ulceration -- that you apply to the dog several times per day. Dogs with episcleritis may require lifetime therapy for this condition.

Secondary Redness Due to Ulceration

• A scratch on the cornea can be extremely painful for a dog. It can also lead to vision loss or eye rupture if the ulceration is very deep. Any kind of corneal abrasion or scratch can lead a dog to paw or rub at the eye incessantly or rub his eye on the carpet, which in turn creates more trauma to the eye and causes the eye to turn red. Furthermore, be very careful when shampooing your dog; shampoo can be highly irritating and even cause a chemical burn to the cornea. Only a vet can detect a corneal ulcer using a florescent stain and a special light. Treatment requires topical ointments and antibiotics. If the ulceration progresses, which it can do quickly, surgery may be in order.

Conjunctivitis

• Although the conjunctiva is not the white portion of your dog's eye -- it's the pink tissue that surrounds the eye -- conjunctivitis, or inflammation, can cause reddening that may be difficult for the untrained eye to differentiate. Conjunctivitis is the most common eye issue presented at veterinary clinics, according to veterinary ophthalmologist Dr. Ralph Hamor. The eye becomes red due to swelling of the delicate mucous membranes; and, since it itches, the dog may rub his eye on the sofa, bed or carpet, further exacerbating the redness. Conjunctivitis is treated with a prescription of an antibacterial agent. You must be diligent when administering eye drops to your dog.