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Fat Soluble Vitamins, Everything You Need to Know

Fat soluble vitamins for pet health

If you haven't already read our intro to vitmains and critical role they play in your pet’s health, you can check it out over here

Now that you've got the basics, let’s explore the fat-soluble vitamins more closely ...


There are two types of vitamin A: 

  1. Preformed vitamin A: vitamin A is found in animal sources, such as dairy, fish and meat
  2. Provitamin A carotenoids: the body naturally converts carotenoids found in plants into vitamin A

Dogs are able to produce their own vitamin A when they eat plants (option 2: provitamin A carotenoids). 

Cat’s can’t. The only way for cats to get vitamin A (without using a supplement) is to eat meat (option 1: preformed vitamin A).

What are the benefits of vitamin A?

Vitamin A contributes to the overall wellbeing of vision, bone growth, and reproduction and maintenance of epithelial tissue. It also nourishes the skin and mucous membrane linings, as well as the respiratory and gastrointestinal tracts.

Vitamin A is necessary for proliferation and differentiation of cells. It’s also required to produce mucoproteins in mucus, as well as normal skeletal, tooth and reproductive performance. 

While there is no definitive proof, vitamin A is suspected to play a role in weight management.


  1. We know this one comes from sunlight. But there is more to it than that. 

Vitamin D is also known as calciferol. It’s another fat-soluble vitamin naturally found in a few foods (like eggs, meat and fish), and manually added to others (like cereal, tofu and yogurt). 

It is also available as a dietary supplement, and is produced internally when ultraviolet (UV) rays from the sun penetrate the skin triggering vitamin D synthesis.

What are the benefits of vitamin D?

The primary function of Vitamin D is to enhance intestinal absorption, mobilization, retention and bone deposition of calcium and phosphorus.

Vitamin D affects the intestines, bones and kidneys by increasing plasma, calcium and phosphorus to the level necessary to allow mineralization and remodeling of bone.

Signs of vitamin D deficiency

A vitamin D deficiency can cause impaired bone mineralization, resulting in osteomalacia in adult animals and rickets in younger animals. Watch for signs of a vitamin D deficiency in your pet, such as vomiting, loss of appetite, increased thirst and urination, excessive drooling and/or weight loss.


RELATED POST: Vitamin D: The Critical Role it Plays in Your Pet's Health


Vitamin E is synthesized from plants. Your pet gets his vitamin E by directly eating the plant, or by eating the animal that ate the plant (small amounts of Vitamin E are found in almost all animal tissues and are incorporated into the membrane bilayer of cells).

Vitamin E is one of the fat-soluble vitamins stored in the liver for later use. The amount of enzymes the liver secretes will determine the effectiveness of the stored vitamins.

What are the benefits of vitamin E?

The primary function of vitamin E is to act as an antioxidant.

In commercially prepared food, vitamin E is susceptible to oxidation and destruction along with the fat in a diet. This is a common occurrence for many vitamins when cooked down at high heats. 

Signs of vitamin E deficiency

When pets have a vitamin E deficiency, it often presents in neuromuscular, vascular and reproductive systems. Most signs of a deficiency are the result of membrane dysfunction, which results from oxidative damage and disruption of the cellular processes.

In addition to decreased fertility, watch for signs of muscle weakness. Severe vitamin E deficiencies can lead to brown bowel syndrome (that’s when the large intestine hemorrhages).


Vitamin K consists of a group of compounds called quinones.

OK, but what’s a quinone? 

Quinones are a class of molecules that prevent and treat illnesses, such as osteoporosis and cardiovascular diseases. Quinones act as antioxidants to improve overall health.

There are three types of vitamin K:

  1. K1: occurs naturally in plants
  2. K2: is synthesized in the large intestine
  3. K3: is synthetic with 2-3x higher vitamin activity than natural K1

What are the benefits of vitamin K?

The best-known function of vitamin K is its role in blood clotting. 

Vitamin K is found in spinach, kale, cabbage and cauliflower, as well as liver, eggs and fish. Most daily requirements of vitamin K are synthesized by bacteria in the large intestine of your pet.

Signs of a vitamin K deficiency

Vitamin K deficiency can occur with intestinal malabsorption diseases, such as exocrine pancreatic insufficiency (EPI) or small intestinal disease. 

Your pet may also become deficient if he ingests poison, or if his microflora (gut bacteria) is destroyed by antibiotics. Vitamin K deficiency can also be caused by congenital defects. 

Sometimes, vitamin K deficiencies are seen in cats who are fed commercial foods with high levels of salmon or tuna.

Learn more about water soluble vitamins here:

RELATED POST: Water Soluble Vitamins: What You Need to Know

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