Supplements for dogs

1. Does my dog need vitamins?

Most dogs receive a complete and balanced diet - including necessary vitamins and minerals - from commercially processed dog food, according to the FDA. Dogs fed a homemade diet may need supplements. “It’s absolutely critical, but it should be done to match the diet,” Wynn says. “You can’t just create a meal and give your dog a vitamin.” Check with a veterinarian or nutritionist for help in determining what, if anything, is needed.

2. Is there any danger in giving my dog vitamins?

Possibly. If an animal already eats a balanced diet and receives excess portions of some vitamins and minerals, they could be harmful, according to the FDA and veterinarians.

Too much calcium can cause skeletal problems, especially in large-breed puppies; too much vitamin A can harm blood vessels and cause dehydration and joint pain. Excess vitamin D can prompt a dog to stop eating, harm bones, and cause muscles to atrophy.

She recommends fruits and vegetables to pet owners who want to give extra nutrients. Other than that, she limits her recommendations if a dog is healthy.

“We want to use things that are safe long-term,” Wynn says. “Probiotics fit that bill. That’s probably all I would recommend.”

4. Do dog supplements work?

It depends on what the supplement is used for and how it is manufactured, veterinarians say. Clinical trials are rare. “It’s hard finding quality evidence for the efficacy, much less the need for these products,” Boothe says.

Glucosamine-chondroitin supplements, commonly given to dogs with osteoarthritis, have shown mixed results in testing in humans and animals. A 2007 study published in The Veterinary Journal concluded that dogs treated with glucosamine-chondroitin sulfate showed less pain and more mobility after 70 days of treatment.

But a 2006 study for the National Institutes of Health Glucosamine/Chondroitin Arthritis Intervention Trial concluded that the supplements weren't effective in humans with mild pain. Those with moderate to severe pain may have seen some benefit, but because of the small size of this group the researchers called for more studies.

Fatty acids can help coats look better. Fish oil supplements also can reduce inflammation, according to a study published in the American Journal of Veterinary Research.

Antioxidants such as vitamins C and E also reduce inflammation and help aging dogs with memory problems, Wynn says. But she’s cautious about recommending supplements, especially for young animals that might be on nutritional supplements for many years. “Almost none of them have been tested for long-term safety in dogs,” Wynn says.

Twelve minerals in the table are known to be essential nutrients for dogs. Calcium and phosphorus are crucial to strong bones and teeth. Dogs need magnesium, potas- sium, and sodium for nerve impulse transmission, mus- cle contraction, and cell signaling. Many minerals that are present only in minute amounts in the body, including selenium, copper, and molybdenum, act as helpers in a wide variety of enzymatic reactions.

Dogs can get too much or too little of a specific mineral in their diets. A deficiency of dietary calcium, for instance, causes a condition known as secondary hyperparathyroidism. Recognized clinically for many years in dogs fed meals consisting mainly of meat, this disease results in major bone loss, skeletal abnormalities, and pathological fractures. An excess of calcium, on the other hand, may also cause skeletal abnormalities, especially in growing large-breed puppies. 

Vitamins are organic compounds that take part in a wide range of metabolic activities. Dogs require vitamins in their food, albeit at low concentrations.


Dogs fed diets lacking vitamin E show signs of skeletal muscle breakdown, reproductive failure, and retinal degeneration. Thiamin deficiency can lead to brain lesions and other neurological abnormalities if the depri- vation is sudden and to heart damage and death if it is chronic. Some vitamins, such as vitamin D, are not only essential in small doses, but also toxic in excess amounts.