Help prevent infections, especially if your dog has allergies, by keeping his eyes and eye area clean. Every day I use a hypo allergic wipe to remove any crusts or balls of mucus around her eyes.
Weekly and on bathing days, I trim any hair that's getting too close to her eyes. Obviously, be VERY careful doing this and use a blunt tip scissors. It helps to have a second person hold your little dog's head still.
Finally, on the same weekly/bathing schedule, I put some eye drops in her eyes to clean them.
Here's a good video that shows basic eye care.
If there's no medical reason for tear stains; i.e., blocked tear duct, it's purely a matter of cosmetics if you attack the stains or not. It's the combination of pigment in his tears reacting to light that causes the discoloration.
Dog saliva contains the same pigments; that's why the hair around his lips can turn brown if a dog drools excessively or the hair on his paws turns brown if a dog with allergies licks at them constantly.
You can spend a lot of money at a veterinarian's searching for the cause of tear stains if there's no obvious medical one. Is it worth it if it's nothing more than a cosmetic issue?
There are products such as Angels Eyes that work well to eliminate stains, but you'll have to use them forever. It and others are not cheap and they usually contain antibiotics such as tetracycline, metronidazole, or tylosin, the latter in Angels Eyes.
Most veterinarians will advise you that indiscriminate use of antibiotics can lead to antibiotic resistance. That's a lot worse than cosmetic tear staining especially if your little dog gets a serious disease and his body no longer responds to standard antibiotics.
Angels Eyes has come out with 'natural' versions that don't use antibiotics, but my friends including a Maltese breeder say it doesn't work well. Another product that has worked well for some (and not so well for others) is Four Paws Crystal Eye for Pets.
There are eye wipes designed to remove stains but these can be irritating and should be washed off his face so they don't get into his eyes.
For a homemade, less expensive but less effective, treatment, dip the tip of a Q-tip or cotton ball in 3% hydrogen peroxide and swab the stain to help "bleach" it away. Keep the hydrogen peroxide away from his eyes. By the way, this is not the bleach you use to bleach human hair.
NEVER use real bleach; e.g. Clorox, around the eyes. You may find some websites or old timers that still recommend that but DON"T DO IT. You could cause permanent injury, not to mention pain, to your dog.
Also, a dab of of Vaseline applied daily to the inner corners of the eyes can help reduce the buildup of hair which will help reduce stains.
You'll have to decide for yourself how important it is and what you're willing to do to keep your dog tear stain free.
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