Do Pets Need Multivitamins?

Ask PHP Pete!

Dear PHP Pete,

I want to make sure my pet is receiving the best nutrition possible. Should I be giving him a multivitamin? Are there any risks?


On a Mission for Nutrition

Dear On a Mission for Nutrition,

Vitamins are vital substances that the body requires in small amounts to function normally. They are obtained from food or synthetic sources. There are two main groups of vitamins:

Water-soluble Vitamins

  • Vitamin B1 (Thiamin)
  • Vitamin B2 (Riboflavin)
  • Niacin (Nicotinic Acid, Nicotinamide)
  • Vitamin B6 (Pyridoxine, Pyridoxal, Pyridoxamine)
  • Folic Acid (Folate, Folacin, Pteroylglutaminc Acid)
  • Vitamin B12 (Cobalamin, Cyanocobalamin, Methylcobalamin)
  • Pantothenic acid
  • Biotin
  • Vitamin C (Ascorbic Acid)

Fat-soluble Vitamins

  • Vitamin A (Retinol, Retinal, Retinoic Acid, Beta-Carotene)
  • Vitamin D (Calciferol, Calatriol, Cholecalciferol, Ergocalciferol)
  • Vitamin E (Alpha-Tocopherol, Tocopherol, Tocotrienol)
  • Vitamin K (Phylloquinone, Menaquinone, Menadione, Napthoquinone)

When it comes to pets, feeding them a nutritionally complete diet–as is the case for most commercial diets—should meet their vitamin needs. There are a few situations when vitamin supplements may be beneficial, but there are also times when they may cause harm.

Multivitamin Supplements May Be Appropriate When:

  • You are feeding your pet a homemade diet that has not been certified complete, as it may not contain all the necessary vitamins.
  • A medication depletes vitamins in your pet’s system. For example, penicillamine can bind to vitamin B6 and decrease levels. Vitamin B12 absorption may decrease when using acid-reducing drugs such as omeprazole and ranitidine.
  • Conditions may be improved with the addition of vitamins, such as using vitamin B12 (as methylcobalamin) to help with diabetic nerve pain or using vitamin C to promote iron absorption.

Multivitamin Supplements May Cause Harm When:

  • Given in excessive amounts. Overdosing may occur when fat-soluble vitamins build up in fat. For example, excessive amounts of vitamin E may reduce the blood’s ability to clot.
  • Minerals in multivitamins can alter the effects of some medications. Calcium, iron, magnesium, aluminum, and zinc may decrease the absorption of medications such as ciprofloxacin, doxycycline, levothyroxine, and penicillamine. In contrast, potassium that is given with ACE inhibitors (e.g., lisinopril) or potassium-sparing diuretics (e.g., spironolactone) may lead to high levels of potassium in the blood, which can cause abnormal heart rhythms that can be life-threatening.
  • Vitamins can interact with and increase exposure to a medication. For example, vitamin C given with aluminum hydroxide may lead to aluminum toxicity.

In general, if you are feeding your pet a nutritionally complete diet, adding a vitamin is not necessary. However, if you are concerned that your pet may require additional nutrients, speak with your veterinarian before adding any supplements for guidance on the appropriate use and dosing of multivitamins.

Yours Truly,

PHP Pete