Vitamins & Minerals 101 | Thiamin (B2)
with Savannah Welna of FeedThyDog, Nutrition Advocate

Vitamin B2 (Riboflavin)

Hypothyroid dog? Overweight dog? Exercising Dog? High carb dog? High fat dog? Read on!


Water soluble, limited storage and absorption capacity. Best to provide daily.


Riboflavin is required for the metabolism of fat, carbohydrates, and protein. It has a special role in fat metabolism- so dogs who are losing weight or are canine athletes likely require more Riboflavin for optimal health status. Diets higher in fat should also have increased Riboflavin.

Riboflavin is most known for its role in fat metabolism, but it is also important for skin, eye, and brain health. The B vitamins work together, so often a deficiency of one will affect the other. In this instance, low levels of Riboflavin can negatively affect Pyridoxine status.


There is low risk for toxicity because there is a limit to what the dog can absorb. As with all nutrients, only provide as much as needed for optimal health regardless of toxicity risk.


Extreme deficiencies have been reported through controlled, purified diets that ultimately resulted in muscular weakness, ocular damage, and death.

However, as stated before, many likely need to be aware of marginal deficiencies or suboptimal status. Riboflavin is more bioavailable from animal foods than from plant foods. It is theorized that kibble diets high in plant based food may provide suboptimal riboflavin levels in an inferior form. Commercial kibbles typically have the B vitamins supplemented, but it would certainly be a “won’t hurt, may help” approach to provide the dog with animal-based, fresh sources of Riboflavin if you are feeding a heavily processed food.

Riboflavin is very sensitive to UV light and so cooking food exposed to light (typically how we all cook :) ) can cause losses. Homemade cooked diets often need B vitamin supplementation compared to raw diets- but it certainly depends on what is being fed.

Riboflavin requires adequate protein for absorption- another reason to try to incorporate high quality animal based proteins when feeding foods like kibble.

Other conditions that can negatively impact Riboflavin status include thyroid conditions, chronic kidney disease, and suboptimal magnesium intake.

Bottom line? It is quite possible that many dogs are receiving suboptimal Riboflavin intake because:

-Many dogs are overweight

-Many dogs eat high carbohydrate diets

-Some dogs may not be eating a performance food that provides the extra Riboflavin needed

-Some dogs losing weight may not be eating a food that provides the extra Riboflavin needed

-Many raw fed dogs are often fed high fat diets (unknowingly). Fat displaces Riboflavin as Riboflavin is not found in fat.

High Quality Sources




-Some dairy products (lower in Riboflavin if processing exposes it to light)



-Red Meat

Adding To Kibble

Eggs, lean red meat, heart, and dairy (if tolerated by the dog) are all great ways to boost Riboflavin intake. Liver, while a great source of Riboflavin, should only be carefully added because it is so rich in other nutrients. If you aren’t using nutrient guidelines, stick to the safer choices.

Homemade Diets

Cooked diets very often are supplemented with B Complex supplements because of the losses of many B vitamins. Certainly, cooked homemade diets without organ meats and lean meats could certainly be short in Riboflavin.

Homemade Raw Diets

Homemade raw typically has enough riboflavin because of the inclusion of liver, meat, and other organ meats. However, if the raw diet is high in fat and the dog has low energy requirements, this may result in suboptimal Riboflavin intake.


-Does your dog have any sort of condition or lifestyle that affects their Riboflavin requirement?

-If you feed a homemade diet, cooked or raw, can you identify where the Riboflavin is coming from?

-If feeding milk, does your milk come in containers that block out light?

-If feeding a homemade diet, have you checked how much fat you are feeding?

Sources  & Reading

Today’s sources include DSM in Animal Nutrition, Canine and Feline Nutrition, NRC nutrient requirements, and Vitamins and Minerals 101.