Vitamin A can be found in animal products and plant products. It is fat soluble and can be balanced over time in a properly formulated diet. The form in animal products is called retinol. There are various forms in plant products, but beta-carotene refers to provitamin A found in plants. Cats cannot use beta-carotene but dogs can efficiently convert beta-carotene. Beta-carotene does not have toxicity risk and when vitamin A needs are met, dogs will use beta-carotene as an antioxidant. Retinol is highly bioavailable and easy for the body to use. There is a safe upper limit for retinol, but not for beta-carotene.

Liver and fish liver oils are the the most common and richest sources of vitamin A as retinol.

Vitamin A is critical for growth, reproduction, immune function, and epithelial tissue.

The term vitamin A refers to related chemical compounds, including retinol, retinal, and retinoic acid. Provitamin A refers to beta-carotene- found in plants. Retinol refers to Vitamin A- the form found in animal sources. It is more bioavailable.

Cats cannot convert beta-carotene to active vitamin A, but dogs can. Conversion of beta-carotene is regulated and high amounts are not concerning, unlike retinol. When vitamin A needs are met in the body, beta-carotene will be used as an antioxidant instead.

Fat soluble.

Functions
Vision, bone growth, reproduction, immune function, maintenance of epithelial tissue.

Signs of Deficiency
Impaired growth, reproductive failure, loss of epithelial integrity, dermatoses, fetal abnormalities, immune dysfunction, weight loss. Most detrimental to puppies. Adults can still suffer from skin disturbances.

Signs of Excess
Skeletal abnormalities, fetal abnormalities, various symptoms of excess when in clinical trials. Safe upper limit exists, but is not concrete for adults.

Sources
Fish liver oils, liver, egg yolk. Liver will provide all the A you need very easily.

Vitamin D is a fat soluble vitamin. Even though it is fat soluble, it can be difficult to balance this nutrient over time because of the levels found in food and how much fat has to be consumed with it. Vitamin D3, not D2, is the form that should be provided to companion animals. Vitamin D is critical for normal calcium and phosphorus levels in the blood and for healthy a skeletal system. Vitamin D is also used for absorbing calcium in the gut and is therefore affected by the intake of calcium.

It can be difficult to get enough vitamin D in the diet. Atlantic mackerel, wild pink salmon, and sardines are the richest sources. Dogs do not get enough D from the sun. Supplementation is also a popular option. Eggs provide vitamin D and can round out levels in the diet, but do not provide enough vitamin D on their own. It is noted that dogs with cancer tend to have lower levels of vitamin D- but not always. Refer to lab work.

D3- Cholecalciferol is the form most important for dietary intake. Calcitriol is the active form in the body.

Fat soluble.

Functions
Very involved with normal calcium and phosphorus homeostasis. D3 is stored in the liver, muscle, and adipose tissue. After the compound is transported and changed in the liver, it is transported to the kidney and converted to active metabolites. This happens in response to elevated Parathyroid Hormone (PTH). Decrease in serum phosphorus also stimulates active vitamin D. Active vitamin D functions in normal bone tissue development and maintenance. Is also important in the homeostasis of the body’s calcium and phosphorus pools. Vitamin D stimulates the synthesis of calcium-binding protein which is necessary for the absorption of dietary calcium and phosphorus. When calcium is low in the diet, Vitamin D is used to increase absorption. Also affects normal bone growth and calcification by acting with PTH to mobilize calcium from bone and by causing an increase in phosphate re-absorption in the kidneys. The effect of Vitamin D in the intestines, bones, and kidneys is an increase in plasma calcium and phosphorus to the level that is necessary to allow for the normal mineralization and remodeling of bone.

Signs of Deficiency
Rickets, osteomalacia, nutritional secondary hyperparathyroidism. Overall compromised skeletal system. It is noted that dogs with cancer tend to have lower levels of vitamin D- but not always. Refer to lab work.

Signs of Excess
Hypercalcemia, bone resorption, soft tissue calcification

Sources
Fatty fish, some fish liver oils, egg yolk, and liver. (Liver alone and eggs alone are not enough to cover D needs in recipes without providing excesses of other nutrients.)

Dogs and cats should be fed D3 sources, not D2.

Vitamin K is fat soluble comes in three forms:

Quinones: K1 (phylloquinone) K2 (menaquinone) K3 (Menadione -synthetic not found in nature)

Vitamin K is important for blood clotting, but has been studied in mammals to prevent calcification of tissues, and maintaining  proper insulin sensitivity.

Most, if not all, of vitamin K1 can be synthesized in the gut and meeting the RA is rarely needed. In addition, Vitamin K is often missing from the dietary analysis of foods. A raw diet of meat, bones, eggs, and dairy will provide plenty sources of K2. A fish based diet for cats can result in the requirement for vitamin K supplementation due to an interference to the vitamin K synthesis.

Quinones: K1 (phylloquinone) K2 (menaquinone) K3 (Menadione) K3 is synthetic and not found in nature.

Fat soluble.

Functions
Important for blood clotting- required for liver’s synthesis of prothrombin and other clotting factors.

“There are two natural forms of vitamin K: vitamin K1 and vitamin K2. Vitamin K1, also called phylloquinone, is found in the green tissues of plants, tightly embedded within the membrane of the photosynthesizing organelle called the chloroplast. As the chlorophyll within this organelle absorbs energy from sunlight, it releases high-energy electrons; vitamin K1 forms a bridge between chlorophyll and several iron-sulfur centers across which these electrons travel, releasing their energy so that the cell can ultimately use it to synthesize glucose.” -Dr. Chris Masterjohn, PHD Read more.

A raw diet of meat, bones, eggs, and dairy will provide various forms of vitamin K2.

Signs of Deficiency
Increased clotting time, hemorrhage.

Signs of Excess
None recorded.

Sources
Green leafy plants, liver, some fish meals.

For cats and dogs, up to all of their needs can be met by microbial synthesis in the gut if the animal is healthy. This is not to suggest that some dietary supply is not helpful. Fish based diets fed to cats may interfere with their ability to synthesize enough vitamin K.

Functions
Part of a coenzyme thiamine pyrophosphate- playing a role in the use of carbohydrates for energy and the conversion to fat and the metabolism of fatty acids, nucleic acids, steroids and some amino acids.

Thiamine needs depend on carbohydrate level in in the diet.

Signs of Deficiency
Affects the function of the CNS because of the dependency on glucose for energy.
Rare.

Signs of Excess
N/A

Sources
Lean pork, beef, liver, wheat germ, beef heart. Thiamine can often be short in homemade diets not using nutrient requirements.

Raw feeders should be aware of thiaminase

https://therawfeedingcommunity.com/2018/05/19/thiaminase-in-raw-fish/

Functions

Cellular oxidation-reduction enzyme systems. Part of the coenzyme NADH & NADP- crucial for cellular respiration resulting in ATP. In other words, energy metabolism!

Deficiencies appear quicker than other nutritional deficiencies.

Signs of Deficiency
Pellagra, and at extreme loss can result in death and also affects the brain

Signs of Excess
N/A

Sources
Liver, some fish meals, chicken, turkey, animal products in general. Plants are not a digestible source because this vitamin is found bound in plants.

Comprises three different compounds: pyridoxine, pyridoxal, pyridoxamine

Functions
Energy metabolism, DNA and RNA synthesis, red and white blood cell formation, synthesis of antibodies and neurotransmitters. Important to some extent glucose and fatty acid metabolism. It is required for the conversion of tryptophan to niacin. Therefore, vitamin B6 requirements are influenced by the level of protein in the diet.

Signs of Deficiency
Microcytic hypochromic anemia, convulsions, muscle twitching.

Signs of Excess
None Recorded

Sources
Organ meats, fish, wheat germ

Functions
Required for the hydroxylation of amino acids proline and lysine in the formation of collagen and elastin for the synthesis of acetylcholinesterase. Important for normal bone formation. Crucial for connective tissue health.
Part of the antioxidant defense system.

Deficiencies appear quicker than other nutritional deficiencies.

Signs of Deficiency
In humans, we would call it scurvy. But dogs and cats do not have a dietary requirement for vitamin C.

Signs of Excess
Digestion upset and diarrhea. Can negatively affect some types of stone formers.

Sources
Vitamin C is produced in the liver from galactose or glucose.

This does not mean that there is no benefit or harm from dietary supply. Some working dogs likely will benefit from C in the diet- as might some dogs exposed to environmental toxins.

Functions
“Pan”- occurs in all body tissues and in all forms of living tissues. This vitamin is critical for energy metabolism an the metabolism of macronutrients. It is found in many different foods.

Signs of Deficiency
Anorexia, weight loss

Signs of Excess
None Recorded

Sources
Organ meats, fish, wheat germ, many foods.

Functions
Involved in the synthesis of thymidine, a component of DNA. Deficiency therefore can result in the body’s inability to produce adequate DNA and subsequently decreased cellular growth and maturation.

Signs of Deficiency
Anemia and leukopenia, impaired immunity

Signs of Excess
None Recorded

Sources
Liver, kidney, and moderate amounts in low fat meats. Organ meats are the richest sources, especially liver.

Functions
Acts as a donor of methyl units for various metabolic reactions in the body. A precursor for the neurotransmitter substance acetylcholine and necessary for normal fatty acid transport in cells. Integral part of cell membranes. Component of 2 phospholipids- lecithin and sphingomyelin. Important for liver health and low intake of folate can increase requirements.

Signs of Deficiency
Neurological Dysfunction

Signs of Excess
Diarrhea

Sources
Dietary deficiencies are rare and is often missing from food analysis. Choline is synthesized with the presence of b12 and folacin. A lot can be synthesized to meet daily needs but that is not to say that dietary supply does not benefit the animal.

Eggs and liver are good sources.

Unfortunately, supplementing is difficult. Food forms (such as lecithin) will not tell how much elemental choline is in it. It must be calculated. Choline bitartrate has lower absorption and may be harmful to the gut. However, when choline is needed in higher amounts, pros and cons must be weighed.

Check out the choline database