What Are the Causes of Enlarged Pupils in a Dog?

Dogs can develop health and vision problems, just as humans can. When you notice that your dog's pupils are enlarged it is important to contact your veterinarian to find out the possible causes for it. Your vet may recommend you to a veterinarian who specializes in animal eye health. Never attempt to treat your dog's dilated pupils before letting your vet examine your pet.

  1. Glaucoma

    • Glaucoma is a vision disease that affects dogs. The disease is the buildup of pressure in the eye, due to the inability of fluids to flow and drain out of the eye. One of the symptoms of canine glaucoma is dilated pupils. Even when exposed to light, the pupils will not respond normally, which is how vets check for glaucoma. Surgery is a likely treatment for glaucoma in canines, but the disease is incurable. In some cases, a veterinarian can remove the eye can to eliminate the pain and pressure caused by the disease.

    Progressive Retinal Atrophy

    • Progressive retinal atrophy is the name of a category of eye conditions that describe similar vision diseases. These diseases affect the retina of the dogs' eyes and can lead to permanent blindness, although the diseases are not painful. Dilated pupils is one of the eventual symptoms you will see with progressive retinal atrophy, but this symptom does not come right away or at the onset of the disease. One of the first symptoms of progressive retinal atrophy is the dog's sensitivity to light and decreasing vision in dimly lit environments.

    Stress

    • Dogs exposed to highly stressful situations, such as with police work or war conditions, can develop dilated pupils as a response to the stress they are feeling, according to Rita Martinez from the Institute of Canine Forensics. Dilated pupils can occur at the onset of the stressful situation, or can be a symptom that occurs post-stressful event. Getting the canine back into a relaxed state helps relax the eyes, too, so that the dilation decreases and returns to normal.

    Toxicity

    • Exposure to a toxic plant by ingestion can cause enlarged pupils in dogs. Jimson weed is an example of a toxic plant that results in the dilation of dogs' eyes as one of the symptoms of exposure. Enlarged pupils are among the earlier symptoms of dog toxicity, with the most severe effect being death.

    Medication Side Effects

    • If your dog is taking medication for any type of health-related treatment, the side effect of the medicine could be enlarged pupils. Always check the warning and side effect labels of pill bottles, or check with your vet, before administering the medicine to your dog. Once your dog is on medication, keep an eye on its pupils to see whether they change.