Essential Fat Soluble Vitamins for Dogs

Essential Fat-Soluble Vitamins for Dogs was updated in January 2020 to add additional details about Fibrous Osteodystrophy to the fat-soluble vitamins for dogs, vitamin D tab.

• Fat-soluble vitamins are A, D, E, and K. These vitamins are digested and absorbed using similar mechanisms as dietary lipids. The metabolites are excreted in a dog’s feces via bile.

• Fat-soluble vitamins can be stored in the body (e.g., liver). As such, toxicity is possible.

• Maximum recommendations are provided for vitamins A and D.

• Vitamins are expressed in various units of measurement with IU, mcg, and mg being the most common. The precise measure of one IU differs from vitamin to vitamin.


IU, International Unit • RE, Retinol Equivalent • RA, Retinol Activity • RAE, Retinol Activity Equivalent • mcg, Microgram • mg, Milligram • g, Gram

fat soluble vitamin for dogs (vitamin a)



Many Forms

Retinol (most biologically active), retinal, retinyl esters; retinoic acid.

Animal sourced vitamin A such as in liver is preformed/retinol. 


Fish liver oils, egg yolk, and animal liver are rated as rich sources, but not if the animal from which they came was fed a vitamin A-deficient diet for an extended period.

Primary Roles in the Body

Tooth and bone growth
Maintenance of epithelial tissues
*Skin; mucous membranes in the gut and respiratory tract
Immune function
Proliferation and differentiation of cells


Can be metabolized into vitamin A
Plant carotenoids
 β-carotene (Dogs can utilize)

*Conversion of β-carotene
      From IU to mcg:  IU/1.66 = mcg
      From mcg to IU: mcg * 1.66 = IU

β-carotene considered to have a low toxicity

High concentrations of β-carotene:
Sweet potato

Almost all the carotene is cleaved in the intestine

Signs of Deficiency

Impaired growth
Reproductive failure
Poor epithelial integrity

Signs of  Preformed Vitamin A Toxicity

Deforming cervical spondylosis
*200−800 times requirement for 4−24 weeks

fat soluble vitamin for dogs (vitamin d)



Two Pro-Vitamin Forms

Cholecalciferol (D3- animals)
Ergocalciferol (D2- plants)
inactive, must be hydrolyzed.


Oily/Fatty fish, egg yolk, some fish liver oils, and liver.

*Liver should not be used as a primary source of vitamin D in the diet as it will elevate levels of other nutrients (such as vitamin A) in excess. Some animal livers do not offer as much vitamin D as other.

Primary Roles in the Body

Vitamin D’s functions are intricately involved with normal calcium and phosphorus homeostasis in the body. At the site of the intestine, vitamin D stimulates the synthesis of calcium-binding protein, which is needed for efficient absorption of dietary calcium & phosphorus. Vitamin D affects normal bone growth & calcification by acting with Parathyroid Hormone (PHT) to mobilize calcium from bone and by causing an increase in phosphate reabsorption in the kidneys. 

Dogs need to be fed Vitamin D in their diet 

Signs of Deficiency

 Nutritional Secondary-Hyperparathyroidism
 *Fibrous Osteodystrophy
*Dogs fed predominantly ratio diets without vitamin D supplements develop fibrous osteodystrophy rather than rickets, owing to nutritional secondary hyperparathyroidism

Signs of Toxicity

 *Soft Tissue Mineralization
*Soft tissue mineralization secondary to persistent hypercalcemia and hyperphosphatemia.

fat soluble vitamin for dogs (vitamin e)



Many Forms

Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. D-Alpha-tocopherol is the most biologically active of these compounds.


High amounts of Alpha-tocopherol are found in wheatgerm oil, safflower oil and sunflower oil.

Primary Roles in the Body

Acts as an antioxidant in plasma, red blood cells, and tissues
Scavenges free radicals that are generated in the body by several processes: energy metabolism, detoxification,
biosynthesis, etc.
Vitamin E has high lipid solubility, allowing its presence in membrane bilayer rich
Prostaglandin synthesis
Regulation of protein kinase activity

Dietary Requirement Dependents
Rate of free radical production
PUFA composition of membranes/diet
Presence of other protective nutrients (e.g., Selenium)  

Signs of Deficiency

Reproductive failure
*State in which PUFA in body are oxidized
*Inflammation of adipose tissue

Clinical Signs of Deficiency
Painful thorax and abdomen

Signs of Toxicity

Interference with vitamin A, D, and K absorption and metabolism

fat soluble vitamin for dogs (vitamin k)VITAMIN K


Many Forms

Phylloquinone (K1)
Menaquinone (K2)
Menadione (K3)

The two major natural sources of vitamin K are phylloquinones (vitamin K1) in plant sources and menaquinones (vitamin K2) produced by bacterial flora. 

Dogs can synthesis vitamin K in the intestinal by microbiota 


Liver, some fish, green leafy vegetables.

Primary Roles in the Body

Important for blood clotting

Signs of Deficiency

Increased blood clotting time

Signs of  Toxicity

None on record 

3 thoughts on “Essential Fat Soluble Vitamins for Dogs

  1. Amy, you website is amazing! I’ve learned so much from you and thanks to you, I feel confident on how to provide the best nutritionally sound diet for my dog.

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