Pet Vet: A look at some causes of vision problems in dogs

October 12, 2014

Hulu is apparently having trouble with his eyesight. This especially appears to be the case when there is lower ambient lighting. His caretakers, who wish to remain nameless, have watched Hulu bump into objects in the house with increasing frequency over the last two months and are wondering if he might have cataracts.

Before I delve into Huluís case, I want to make it very clear that if you as a caretaker of an animal, regardless of species, and you notice a change in their eyesight, take them to their veterinarian. Eyesight degradation can be an indication of several potentially serious conditions.

Madam X and/or her partner did not share with me what breed of dog Hulu might be, but they did share that they have noticed: Huluís eyes appearing to turn somewhat blue over the last few months. This might offer a clue as to why his eyesight is worsening.

Rather than list a bunch of possible causes for decreasing vision in dogs, letís focus on some of the more common conditions that might be causing Huluís partial blindness and also one potentially very serious cause that can lead to blindness in dogs.

Cataracts, as mentioned by Huluís caretakers, can indeed cause partial and in many cases, total blindness. Cataracts involve the lens and/or the lens capsule of the eye and show as an opacity. They prevent normal vision. They can be present from birth or become acquired as a dog ages. They can also occur as a result of underlying metabolic disease the most common of which is diabetes mellitus. Cataracts are easily diagnosed by a veterinarian and if causing total blindness, they can be removed to allow a return of some vision.

Another very common potential cause for a decrease in vision in dogs is a process called lenticular sclerosis. This process is a normal part of aging of the lens in the eye that results in the lens crystallizing to the point of blocking some light from reaching the retina in the back of the eye and producing a visual image. This process does produce a blue cast to the eye as the lens becomes more crystalline.

Total blindness does not result from lenticular sclerosis and some of these patients do not appear to suffer any vision loss. Some patients with this lens change however will have problems seeing in low ambient light situations owing to the fact that the lens lets less light through and there is less light available to begin with. If I was to wager a guess, I would bet Hulu has lenticular sclerosis.

One eye disease that is very serious and will cause total blindness is glaucoma. This disease results from an increase in the fluid pressure within the eyeball, which left unchecked, causes destruction of the retina in the back of the eye rendering the eye functionless. This disease process is very painful.

The problem with glaucoma in dogs is that we seldom catch it before vision is destroyed as our companions do not show symptoms early enough in the disease course so that we can intervene. The symptoms that we do note are redness around the eyes and often a blue cast to the eyes with redness in the white portion of the eyes. These dogs will sometimes rub their eyes in response to the discomfort from the increased intraocular pressure. If your dog ever shows any of these symptoms, have him seen immediately by his veterinarian. Glaucoma is treatable in many cases and if caught early enough, vision can be saved.

Again, the list representing reasons for vision loss in dogs is protracted but in Huluís case, I suspect his condition is not serious. That said, a veterinary visit is necessary to verify my assumption, an assumption I hope to be correct.



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