By Jennifer Kvamme, DVM
We've all heard the saying that eating carrots can help improve vision. But does this apply to our dogs as well? While there is some hint of truth in the concept, eating bushels of carrots will not give your dog (or you) super vision during the day (or night).
Carrots are indeed a nutrient-rich source for a variety of vitamins and minerals, including beta-carotene, a pigment that gives carrots and other vegetables their signature orange (or sometimes yellow or red) color. It is the beginning form of vitamin A (called retinal) that is necessary to maintain good vision — especially in dim light.
How Does Beta-Carotene Help?
When your dog eats foods containing beta-carotene, it is absorbed by the intestine and transported to the liver. There it is combined with fats in the diet, converted to vitamin A, and stored until it is required by the body. When called upon, it is released through the bloodstream, and from there travelling to the retina of the eye.
The retina is critical for normal eyesight. Found in the back of the eyeball, it is made up of millions of cells called rods and cones. These cells are sensitive to light and use vitamin A to tell the brain (via the optic nerve) what is being seen. The rods are most important in low-light situations, and the rods are sensitive to low levels of vitamin A in the body. So, if your dog has a deficiency of vitamin A, eating more foods that contain beta-carotene could help improve eyesight, especially at night.
Beta-carotene also works as an antioxidant, helping to prevent disease and infection. Its role as a precursor of vitamin A makes it important for healthy skin and hair coat, normal bone development, reproductive health, general eye health, and cancer prevention.
Beta-Carotene/Vitamin A in the Diet
Carrots are not the only source of this important nutrient in your dog’s diet. Ingredients such as liver, eggs, sweet potato, spinach and broccoli also contain beta-carotene. Vitamin A and beta-carotene are also created synthetically and added to dog food to make sure the levels provided are adequate for daily nutrition.
There is, however, such a thing as having too much vitamin A in the diet. Dogs that have too much in their diet (hypervitaminosis) can develop bone problems and muscle weakness. Thankfully, reaching a toxic level of vitamin A would require a very high dose over a long period of time, and giving your dog a few carrots now and again isn’t going to come close to providing an overdose. If you do choose to give your dog carrots as an occasional treat, it's best to cut them up into small enough pieces to reduce the risk of choking or gastrointestinal discomfort.
At high levels of beta-carotene supplementation, the pigment may cause your dog's skin (or white hair) to turn yellowish or orange in color. Dogs with red or brown hair coats may develop a darker color hair coat at higher levels of ingestion. Once the high levels of beta-carotene are reduced, the color will go away quickly.
While feeding your dog carrots or buying dog foods that contain sources of beta-carotene can provide health benefits, there is not much chance of your pet's eyesight becoming better than it was before. That said, there is little chance that beta-carotene supplementation will improve diminished eyesight caused by injury, cataracts, glaucoma, etc. However, beta-carotene has even been shown to prevent cataracts and other eye diseases when used prophylactically.
Chew BP, Park JS, Wong TS, Kim HW, Weng BB, Byrne KM, Hayek MG, Reinhart GA. "Dietary beta-carotene stimulates cell-mediated and humoral immune response in dogs." Journal of Nutrition Aug. 2000: 130(8);1910-3.
Karutz, M. "Stable β-carotene Formulation for Petfood." Petfood Supplement, Issue 10.