Cataracts in Dogs

Alex German
Jan 15, 2010
Image: Photo Grapher / via Image Bank

Cloudiness of the Eye Lens in Dogs

Cataract refers to the cloudiness in the crystalline lens of the eye, varying from complete to partial opacity. When the eye lens (located directly behind the iris) is clouded, it prevents light from passing to the retina, which can cause vision loss.

Most cases of cataracts are inherited. For instance, Miniature poodles, American cocker spaniel, miniature schnauzer, golden retrievers, Boston terriers, and Siberian huskies are all predisposed to cataracts.

Symptoms and Types

Symptoms typically relate to the degree of vision impairment. Dogs with less than 30 percent lens opacity, for example, display little or no symptoms, whereas those with more than 60 percent opacity of the lens may suffer from loss of vision or have difficulty seeing in dimly lit areas.

Meanwhile, if your dog has diabetes mellitus-related cataract, you may also observe increased thirst, increased frequency of urination, and weight loss in your dog, along with vision impairment symptoms.


Although most cases of cataracts are inherited, the following are other causes and risk factors associated with the condition:

  • Diabetes mellitus
  • Old age
  • Electric shock
  • Inflammation of the eye's uvea (uveitis)
  • Abnormally low levels of calcium in blood (hypocalcemia)
  • Exposure to radiation or toxic substances (e.g., dinitrophenol, naphthalene)


If you should observe cloudiness in one or both of the dog's eyes, you should bring it in to see a veterinarian immediately. There, the veterinarian will ask for a thorough history of your dog’s health, including the onset and nature of the symptoms, and possible incidents that might have precipitated the problem. He or she will then perform a complete physical examination, focusing on the eyes and ocular region, to determine the severity of the problem.

Routine diagnostic tests, such as complete blood count, biochemistry profile, and urinalysis, may be conducted. However, the results of these tests are usually non-specific unless another concurrent disease like diabetes mellitus or hypocalcemia are at the root of the problem. Ultrasounds or electroretinography (which measures the electrical responses of cells present in the retina) are two forms of advanced diagnostic exams which also help determine the severity of the issue and may confirm whether surgery is necessary to correct a cataract.

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