Thiamine (B1) is an essential vitamin for dogs but also a fragile nutrient that can easily be at low levels in both commercial and homemade adult dog food diets.

Thiamine levels are - and should be - of concern to dog parents due to the potential role a thiamine deficiency plays in chronic illness (like diabetes).

Let's jump into how to provide whole food sources of thiamine and, when necessary, to spot the signs that help diagnose thiamine deficiency in dogs and implement thiamine deficiency treatment.

What is thiamine (vitamin B1)

Thiamine, vitamin B1, is a water soluble vitamin that is required in the diet. Dogs have limited abilities to store thiamine so it's best provided daily.

Thiamine has no known toxicities and is one of the safest vitamins to provide in the diet from food or thiamine supplementation as needed.

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What thiamine does for our dogs

Thiamine is critical for energy metabolism and plays a special role in carbohydrate metabolism. Specifically, B1 is required in the pentose phosphate cycle- critical for the brain, liver, kidney, and adrenal cortex. For that reason, a thiamine deficiency can affect the brain since the brain runs on glucose. Thiamine also helps your dog recycle other nutrients (like pantothenic acid and folate).

The important role thiamine plays in your dog's health and well-being cannot be understated. You need to provide whole food sources of thiamine and, when necessary, to spot the signs that help diagnose thiamine deficiency and implement thiamine deficiency treatment. Ensuring thiamine intake is adequate for your dog is essential for optimal health.

What is the impact of vitamin B1 deficiencies

In adult dogs, thiamine deficiencies include neurological signs and physical manifestations like anorexia, inappetence, mental dullness, vomiting, ataxia, and muscular weakness (to name a few). Thiamine deficiency starves the brain of glucose.

Could processed foods and thiamine-deficient intake be contributing to diabetes in dogs? It's a reasonable concern and more reason to keep an eye on your dog's thiamine concentrations in food and whether they meet dietary thiamine requirements.

Where thiamine is found in food

Thiamine is found in a variety of foods:

• Lean meats
• Fish
• Poultry
• Eggs & dairy products
• Brewer’s yeast, fortified grains & whole grains
• Legumes
• Nuts
• And with pork providing the highest amount.

Some thiamine is also available from plant sources such as broccoli, spinach and peas. We recommend providing thiamine-rich whole food sources to ensure thiamine concentrations are optimized.

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Thiamine deficiency risk factors

Commercial pet foods: low thiamine & carb-metabolizing issues

Thiamine is extremely fragile. In alkaline environments, thiamine is rapidly destroyed. It is also very sensitive to heat. In commercial pet foods (kibble and canned diets) the majority of thiamine is destroyed and must be supplemented back in some way.

Because thiamine is required for carbohydrate metabolism, processed, low-quality commercial pet foods or canned diets (or any diet with insufficient thiamine content) that doesn't provide adequate supplemented thiamine can cause disturbances in carbohydrate metabolism and potentially allow glucose to build up in the blood.

We know that, in humans, thiamine deficiency is observed in individuals with diabetes, suggesting a link with the rise in diabetes in dogs as well.

Raw fish & its impact on thiamine

Thiaminase is an enzyme that breaks down thiamine. It can be found in many different types of fish but cooking reduces its activity. Thiaminase can harm thiamine status even if enough thiamine is fed. That's why raw fish containing thiaminase should not be mixed into food that is stored and should not make up a large part of your dog's diet.

Preservatives that destroy thiamine

Sulfur-based preservatives destroy thiamine in food. Generally, homemade feeders do not need to worry about this if you are feeding fresh food that does not use preservatives. Always check for added ingredients as even fresh meat with small amounts of sulfur dioxide can significantly harm thiamine status.

While foods containing products that increase pH also result in thiamine destruction, I don’t consider this a major risk for feeders adding fresh food to the diet.

Kidney conditions and polyuria

When any condition causes increased urine excretion, thiamine can be depleted. When large amounts of urine are passed and when the kidneys are unable to absorb thiamine or reabsorb it, extra thiamine must be supplied in the diet for optimal health.

High fat diets

Thiamine is not found in fat. Unbalanced diets that are high in fat and do not supplement thiamine are likely low in this nutrient. This issue is more common in raw/cooked feeders who feed high fat food to low energy dogs.

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Practical applications for your dog

While extreme thiamine deficiency results in many of the symptoms outlined above, subtle thiamine deficiency can be harder to catch and is often not on the radar. Given the neurological functions in the brain and the fact that thiamine is extremely fragile, some neurological signs can be indicators.

It makes sense to suggest many dogs may not be receiving optimal levels of thiamine. It seems reasonable for those feeding kibble dog food to provide fresh sources of thiamine (above) and for DIY feeders to provide enough thiamine as well.

How to add thiamine to your dog's diet

Thiamine can be extremely tricky to get from food and can often be left out in unbalanced commercial dog food and homemade diets. If thiamine is not added and the diet does not provide thiamine in sufficient amounts, that's when thiamine deficiency in dogs can occur.

For those looking to supplement thiamine, there are many options available on the market today. The best source of thiamine for dogs is pork since it contains a large amount of thiamine.

The richest levels of thiamine can be found in:

• Pork
• Duck
• Heart
• Nutritional yeast
• Liver
• Kidneys

Thiamine is relatively higher in many digestible carbohydrates including buckwheat, quinoa, sweet potatoes, grains, and other lower starch options like butternut squash. These should all be cooked to be digestible for your dog.

However, even including kidney and liver in the diet will not result in optimal thiamine intake. Nutritional yeast is high in vitamin B such as thiamine but often fortified with undesirable added ingredients.

While meat in general provides thiamine, dogs who have low energy requirements are more likely to need a thiamine supplement. 

Adding thiamine to commercial dog food

Canned and kibble dog food can be safely topped with lean pork, duck, and heart (multiple protein sources) and some amount of sweet potatoes and squash can provide phytonutrients in addition to B1. Most commercial pet foods are already high in starch, so focusing more on animal products makes sense to boost thiamine content in your dog's food.

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Steps to evaluate thiamine (B1) in your dog's diet

1. Identify thiamine in your dog's food: Most canned and kibble dog foods will be fortified with thiamine. If you are feeding homemade or commercial, identity the thiamine sources- especially if you're a DIY feeder or feeding local raw food blends.
2. If you're feeding canned and/or kibble: how can you add fresh thiamine to your dog’s diet (start by checking options in list above)?
3. Are you feeding any sources of sulfur-based preservatives or fish that contain thiaminase?

Next up in the Basic Nutrition Channel on Dogly

Now that you have a good understanding of vitamin B1/thiamine, let's continue to the next essential B vitamin step-by-step guide: B2/ riboflavin.

Or hop over to the Basic Nutrition Channel if you'd like to ask a question in the Community discussion and start any of the other step-by-step guides in Needed Nutrients.

If you ever need more personalized nutrition guidance, please reach out!

Sources

NCBI 1

NCBI 2

DSM

NRC Nutrient Requirements of Dogs and Cats

Canine and Feline Nutrition