Vitamins are regulatory molecules that function as enzymes, enzyme precursors, or coenzymes. Their primary function is to promote and regulate a wide variety of physiologic processes. Vitamins are divided into two groups: fat soluble ( Vitamin A, D, E, K) and water soluble  (B Complex) vitamins.

Vitamin A is essential in skeletal growth, proper eye function, healthy skin and mucous membranes. Vitamin A is also the body’s first line of defense against invading microorganisms and toxins. It promotes a healthy immune system, destroys cancer causing agents and guards against heart diseases and stroke. Vitamin A is very sensitive to processing temperatures, in commercial pet food manufacturing, the process involves greater than 140 degrees C, in turn leads to loss of Vitamin A activity in the kibbles.  Vitamin D (sunshine vitamin) is also essential and is effective chain breaking lipid-soluble antioxidant in the biological membrane. It contributes to membrane activity, protecting cellular structures against damage from oxygen free radicals. Vitamin E  works as antioxidant, deficiency causes muscular dystrophy, reproduction failure and impaired immunity.  Vitamin K is essential for blood clotting. Toxicity of Vitamin A and D is common, excess intake can’t be excreted so toxicities of Vitamin A and Vitamin D occur. There is an increase of vitamin D supplement usage by pet owners for their health, if those pill bottles are not kept away from their pet, there is a good possibility that dog can grab and eat them, it definitely causes vitamin D toxicity.

Thiamin is a B vitamin, signsof deficiency is quite common, because of the body’s limited storage capacity, signs of deficiency appear in a shorter time after exposure to a thiamin-deficient diet than for  most other vitamins. Recently, FDA recalled several commercial pet food products having dangerously low levels of thiamin. Cats are more susceptible to thiamin deficiency than dogs, because they require about four times as much thiamin in the diet.  Riboflavin (B2) deficiency causes dry, scaly skin and muscular weakness. B2 deficiency in dogs causes anorexia and weight loss. Niacin is an essential B vitamin,  dogs can synthesize from tryptophan amino acid, its deficiency causes black tongue disease.  Pyridoxine (B6) deficiency  in newly weaned puppies  produced anorexia, in older dogs, the deficiency shown as convulsions and muscle twitching. Pantothenic  acid is an integral component of CoA, its content is high in organs, like liver and kidney. A pantothenic acid deficient diet resulted in erratic food intake of puppies within 2 to 3 weeks and adult dogs within 7 to 8 weeks, Vitamin B12 (cobalamin) is known for appetite stimulant.  B12 is abundant in animal foods.  Prolonged deficiency of folic acid in dogs showed a decline in hemoglobin concentration in blood. Biotin deficiency symptoms in dogs include scaly dermatitis, anorexia, dried saliva around mouth and secretions around eyes. Choline is essential to older dogs, it helps in minimizing fatty liver by providing methyl groups.

Supplementing a well balanced vitamin supplement to dogs is increasingly important to home cooked dog foods, low quality processed dog kibbles or even to high quality dog kibbles due to loss vitamin activity during high processing temperatures.


Dr. PV.Reddy., DVM, Ph.D