My dog often has bloodshot eyes,..

Brief：
Answers: Bloodshot eyes are a common occurrence for the simple reason that dogs and cats are energetic, curious creatures that approach the world head.. 

Answers:

Bloodshot eyes are a common occurrence for the simple reason that dogs and cats are energetic, curious creatures that approach the world headfirst. They don't always have time to duck or blink when running face-first through high grass, under branches, or under the bed. Even a little scratch or irritation in the eye can cause major redness in their eyes, not just for an hour or two, but sometimes for a few days.

There is another reason that they are prone to bloodshot eyes. Unlike people, dogs and cats have third eyelids, which are designed to protect the eyes from foreign objects, says Paul M. Gigliotti, D.V.M., a veterinarian in private practice in Mayfield Village, Ohio. Sometimes, however, bits of wood or other debris get trapped under the lid, making the eye sore and irritated. "A foreign body in the eye is the most common cause of bloodshot eyes," he says. In fact, when only one eye is bloodshot, you should suspect that's the cause.

When both eyes are bloodshot, however, you can be pretty sure that something is happening elsewhere in the body. Pets with allergies, for example, will sometimes get red eyes. could be cherry eye it's that time of year again take him to a vet now Does he get enough sleep, that might be the problem. If he does get enough sleep, make sure he's not near something he might be allergic too. Your dog is possibly sick. Take him to the vet for a checkup I have a Boston Terrier, and her conjunctiva will be red if she gets too hot. We didn't realize the connection until we'd had her for a while, so you might try cooling the dog off and see if there's a connection there. It's one of the signs of worms,but there could be something in the air doing it too,dog get allergies to quit smoking dope in front of him that should cure it Could be it has allergies, is tired, has a foreign body in it's eyes often, or has entropian (eyelashes roll in rubbing eye), a condition common in some breeds (Shar Peis almost all have it, some Rottweilers have it also) that can be corrected wil surgery. Best to have it checked by your vet to rule out & possibly avoid further damage. If your dogs eyes are bloodshot, I would recommend taking him to the vet for diagnosis.