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.
Glossary:
IU, International Unit • RE, Retinol Equivalent • RA, Retinol Activity • RAE, Retinol Activity Equivalent • mcg, Microgram • mg, Milligram • g, Gram
Animal sourced vitamin A such as in liver is preformed/retinol.
Sources
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
Vision Tooth and bone growth Reproduction Maintenance of epithelial tissues *Skin; mucous membranes in the gut and respiratory tract Immune function Proliferation and differentiation of cells
Precursors
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: Carrots Pumpkin Sweet potato
Almost all the carotene is cleaved in the intestine
Deforming cervical spondylosis *200−800 times requirement for 4−24 weeks
VITAMIN D
FAT SOLUBLE
Two Pro-Vitamin Forms
Cholecalciferol (D3- animals) Ergocalciferol (D2- plants) inactive, must be hydrolyzed.
Sources
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
Rickets Osteomalacia 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
Hypercalcemia Hyperphosphatemia *Soft Tissue Mineralization *Soft tissue mineralization secondary to persistent hypercalcemia and hyperphosphatemia.
VITAMIN E
FAT SOLUBLE
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.
Sources
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 in PUFA 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 Pansteatitis *State in which PUFA in body are oxidized *Inflammation of adipose tissue
Clinical Signs of Deficiency Depression Anorexia Painful thorax and abdomen
Signs of Toxicity
Interference with vitamin A, D, and K absorption and metabolism
3 thoughts on “Essential Fat Soluble Vitamins for Dogs”
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.
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.
Thank you so much, Sharon!
Thank you for this!