Dogster is reader-supported. When you buy via links on our site, we may earn a commission at no cost to you. Learn more.

Ask the Vet

Thiamine Deficiency in Dogs: 7 Signs to Look For (Vet Answer)

Dr. Joe Mallat
Written and fact-checked by Dr. Joe MallatVet Approved
Dr. Joe Mallat
Reviewed & Fact-Checked byDr. Joe MallatDVM (Veterinarian)
Joe is a veterinarian from Sydney, Australia. When he's not working, he enjoys cooking, exercising, and exploring the Australian wilderness. He has worked for 2 years at a mixed-species practice on the mid-north coast of New South Wales, treating animals of all sizes. His areas of particular interest include wound management, internal medicine, and oncology. Joe's love for the profession comes not only from helping dogs, but also from helping their parents and working with wonderful teams of people.View authorThe information is current and up-to-date in accordance with the latest veterinarian research. Learn more
Updated on June 17, 2026
Share
bottle of vitamin b thiamine

Vitamins are essential to the overall health of people: they help fight infections, metabolize food, heal wounds, and regulate hormones. But what about their role in dogs? Though not often spoken of, they are just as important in our canine friends. This article will focus on Vitamin B1, also known as thiamine. Inadequate thiamine in the body, termed thiamine deficiency, can cause serious neurological issues in dogs.

This article will delve into thiamine deficiency—what it is and what causes it, but, just as importantly, what signs you should be looking out for.

divider single dog paw oct 2024

What is Thiamine?

Thiamine is a water-soluble vitamin that plays a crucial role in carbohydrate metabolism. Carbohydrates are a macronutrient that provide energy and other health benefits. In dogs, they are also the main source of dietary fiber. Dogs are not able to synthesize thiamine. This means that it must be obtained from the diet. Most dogs fed a commercial or store-bought pet food will receive adequate dietary thiamine, and, therefore, are very unlikely to develop thiamine deficiency.

Image By: Maxx Studio, Shutterstock

What Causes Thiamine Deficiency?

Vets recognize four main causes of thiamine deficiency in dogs:

  • Dogs fed a diet without enough thiamine, such as vegetarian diets.
  • Dogs fed raw fish or shellfish diets. These foods contain enzymes that break down thiamine in the body.
  • Dogs fed overly-heated food. Thiamine is heat-sensitive, so is easily destroyed when food is cooked.
  • Dogs fed treats or diets preserved with Sulphur dioxide.
divider dog paws oct 2024

Signs to Watch for

Thiamine deficiency can occur in any breed of dog, at any age. Most of the signs of thiamine deficiency in dogs are attributed to the forebrain. Below are the seven most common signs of thiamine deficiency:

1. Lethargy

Of course, lethargy is seen with a vast number of diseases in dogs, not only thiamine deficiency. Reduced energy levels and a dull or quiet demeanor are early signs of thiamine deficiency.

Image Credit By: Mylene2401, Pixabay

2. Reduced Appetite

This is similar to lethargy—as dogs don’t feel well, they become less interested in eating. This also occurs relatively early with thiamine deficiency. Loss of appetite can be seen with a number of health issues in dogs.


3. Weight Loss

Weight loss occurs days to weeks after thiamine deficiency first develops. This is due to reduced absorption of carbohydrates (energy), decreased food intake (loss of appetite), and increased basal energy expenditure.


3. Vomiting and Diarrhea

Vomiting and diarrhea are non-specific gastrointestinal signs in dogs with thiamine deficiency. Usually, the vomiting and diarrhea are not severe, but “wax and wane”, and fail to resolve without increasing thiamine intake.

Image By: Mumemories, Shutterstock

4. Weakness

Weight loss and reduced muscle mass will lead to weakness in dogs with thiamine deficiency. Thiamine also plays a role in the conduction of nerves through the body, which tells the muscles what to do. Without this, muscle function also becomes impaired. More specifically, weakness appears as the inability to walk or support weight and muscle tremors.


5. Seizures

Seizures occur when thiamine deficiency has been present for a long time, indicating that the problem has become severe. Seizures occur when the function of the brain (in particular, the forebrain) has become impaired. Seizures appear as loss of consciousness, with alternating stiffening and jerking of the legs, and often urination/defecation.


6. Coma

Coma is life-threatening. This is seen with the most severe and untreated cases of thiamine deficiency in dogs. Coma is a prolonged period of unconsciousness and can lead to death.

Is your dog presenting any of these signs? Talk with one of our experts here:

divider dog paws 3 oct 2024

Summary

Thiamine deficiency is rare in dogs. Its occurrence can be prevented by feeding commercial dog foods with adequate thiamine and avoiding raw-fish diets. If you are unsure if your dog’s diet has enough thiamine, don’t hesitate to contact a veterinarian or pet nutritionist. Although the early signs of thiamine deficiency are mild and not life-threatening, the neurological signs that occur later in the disease process are very concerning. This emphasizes the importance of seeking veterinary help early—as soon as you notice that your dog is unwell. Most cases can be diagnosed early based on dietary history, physical examination findings, and blood tests.

Sources

Featured Image Credit: luchschenF, Shutterstock

The Dogster Newsletter

Expert dog care, straight to your inbox

News, insights, expert advice, and everything dog.

No spam — unsubscribe anytime.

By signing up, you agree to our Terms & Conditions and Privacy & Cookies Policy.

Click a star to rate. You can leave written feedback afterwards. (We read all feedback.)

Dr. Joe Mallat DVM (Veterinarian)
Authored by

Dr. Joe Mallat DVM (Veterinarian)

6 Foods High In Thiamine for Dogs: Vet-Approved Vitamin B1 Sources

6 Foods High In Thiamine for Dogs: Vet-Approved Vitamin B1 Sources

Thiamine, also known as vitamin B1, is an essential nutrient for dogs and humans. Dogs require it for carbohydrate metabolism, optimal growth, and efficient ne…

Oliver Jones
By Oliver Jones · 2 weeks ago
Dog Tremors: Causes, Diagnosis & Treatment (Vet Answer)

Dog Tremors: Causes, Diagnosis & Treatment (Vet Answer)

If you notice your dog tremoring, it's normal to feel nervous. Your dog is doing something out of the ordinary. Is it a seizure or something else? Your dog cou…

Dr. Samantha Devine
By Dr. Samantha Devine · 4 weeks ago
Neurological Disorders in Dogs: 11 Vet-Explained Signs

Neurological Disorders in Dogs: 11 Vet-Explained Signs

Neurological disorders in dogs can be alarming for owners to witness and often tricky to diagnose and treat. The nervous system is essentially the electrical s…

Dr. Megan Barnes
By Dr. Megan Barnes · 3 weeks ago
7 Signs Your Dog With Diabetes Is Dying & What to Look Out For (Vet Answer)

7 Signs Your Dog With Diabetes Is Dying & What to Look Out For (Vet Answer)

Having a dog with diabetes mellitus calls for constant observation and care. It is difficult to see your beloved pet battling a chronic illness, and identifyin…

Dr. Marti Dudley
By Dr. Marti Dudley · 4 weeks ago

What to Feed a Diabetic Dog That Won't Eat: 6 Mealtime Tips (Vet Answer)

Diabetes management in dogs can be a complicated dance between timed feedings, insulin administration, and exercise. When all these elements work in concert, a…

Dr. Chyrle Bonk
By Dr. Chyrle Bonk · June 17, 2026
What to Feed a Diabetic Dog That Won't Eat: 6 Mealtime Tips (Vet Answer)

Thyme for Dogs: Our Vet Explains Potential Benefits, Uses & Risks

Thyme (Thymus vulgaris) is a popular spice that many people keep in their homes. You can even grow it in the garden or indoors to have a fresh herb to use in y…

Dr. Luqman Javed
By Dr. Luqman Javed · July 10, 2026
Thyme for Dogs: Our Vet Explains Potential Benefits, Uses & Risks

What Can Trigger a Seizure in a Dog? Our Vet Explains Signs, Causes & Treatment

Seizures can be scary to witness in people and pets alike. Changes in brain activity can trigger a seizure in a dog, though the reasons for those changes vary.…

Dr. Stacie Grannum
By Dr. Stacie Grannum · July 4, 2026
What Can Trigger a Seizure in a Dog? Our Vet Explains Signs, Causes & Treatment

Dog Diarrhea: Our Vet Discusses Signs, Causes & Treatment

Almost all dog owners have encountered diarrhea at some point in their dog's life. A variety of causes can lead to diarrhea in puppies and dogs. Luckily, most…

Dr. Emma Chandley BVM
By Dr. Emma Chandley BVM · June 17, 2026
Dog Diarrhea: Our Vet Discusses Signs, Causes & Treatment

Liver Disease in Dogs: Our Vet Discusses Signs, Causes & Treatments

The liver is an impressive organ! Not only is it like the body’s oil filter, but it also has the ability to regenerate should it become injured or damaged. How…

Dr. Chyrle Bonk
By Dr. Chyrle Bonk · June 29, 2026
Liver Disease in Dogs: Our Vet Discusses Signs, Causes & Treatments

Love Dogs? So Do We! Join the Dogster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.

You may opt-out at any time. View our Privacy Policy for more information.

The Dogster app on a phone