Dog Health Library | Thyroid & Metabolic Health
Hypothyroidism in Dogs: Signs, Testing, Diet & Natural Thyroid Support
Is your dog gaining weight without eating more, losing fur, feeling the cold or simply not acting like themselves? An underactive thyroid can affect far more than energy levels. Understanding what is happening is the first step towards helping your dog feel brighter, more comfortable and more like themselves again.
Written by Erin Follington, Small Animal Naturopath & Founder of Natural Pet Supplements
Important: Hypothyroidism is a medical condition that should be diagnosed and monitored by your veterinarian. Herbal support, appropriate nutrition and lifestyle changes can form part of a broader wellbeing plan, but they do not replace necessary thyroid medication, veterinary advice or follow-up blood testing.
Jump to the question you need answered
- What is hypothyroidism in dogs?
- What are the signs of an underactive thyroid?
- What causes hypothyroidism?
- How is hypothyroidism diagnosed?
- Does my dog need thyroid medication?
- What should a dog with hypothyroidism eat?
- What can I do at home to help?
- Why I created Hypothyroid Support
- Which herbs are in Hypothyroid Support?
- How much Hypothyroid Support should I give?
- What are other dog owners saying?
- Which other products can help support my dog?
- Frequently asked questions
What is hypothyroidism in dogs?
Hypothyroidism means the thyroid gland is not producing enough thyroid hormone.
The thyroid is a small gland in the neck, but its influence reaches almost everywhere. Thyroid hormones help regulate metabolism, energy production, body temperature, skin health, coat growth and the way the body uses nutrients.
When thyroid hormone levels are too low, the body effectively starts running in slow motion.
Your dog might sleep more, put on weight despite eating the same amount, struggle with a dull or thinning coat, or seem less interested in walks and play.
These changes can creep up gradually. Many people understandably assume their dog is just getting older, especially when the symptoms appear over several months rather than all at once.
In simple terms: an underactive thyroid slows the body's normal processes. Supporting a dog properly means looking at the whole picture: veterinary testing, any medication they need, their food, their daily routine and their overall wellbeing.
What are the symptoms of hypothyroidism in dogs?
Low thyroid function rarely affects just one area. Because thyroid hormones influence so many body systems, symptoms can appear in your dog's energy levels, weight, skin, coat, behaviour and comfort.
Energy and behaviour
- Sleeping more than usual.
- Less enthusiasm for walks or play.
- Tiring quickly during exercise.
- Seeming flat, withdrawn or unusually quiet.
- Reduced mental alertness.
- Looking for warm spots around the house.
Skin and coat changes
- Thinning fur, especially along the body.
- A sparse or thinning tail.
- A dry, dull or brittle coat.
- Excessive shedding or slow coat regrowth.
- Darkened or thickened areas of skin.
- Recurring skin or ear concerns.
Weight and metabolism
- Weight gain without an obvious increase in food.
- Difficulty losing weight.
- Reduced exercise tolerance.
- Changes in muscle condition.
- Higher cholesterol identified on blood tests.
- A general feeling that your dog has slowed down.
Comfort and movement
- Reluctance to exercise.
- Stiffness or slower movement.
- Weakness or reduced stamina.
- Preference for resting rather than exploring.
- Greater sensitivity to cold weather.
- Less excitement about normal activities.
None of these symptoms proves that a dog has hypothyroidism. Arthritis, nutritional imbalances, skin allergies, other hormonal conditions and general illness can look similar, which is why the right veterinary testing matters.
A useful clue: if your dog is gaining weight, feeling the cold and developing coat changes at the same time, it is worth asking your vet whether thyroid testing should be part of the investigation.
What causes hypothyroidism in dogs?
In many dogs, hypothyroidism develops because the thyroid gland gradually loses its ability to produce normal amounts of thyroid hormone.
One common cause involves the immune system affecting the thyroid gland. Another is progressive loss of functioning thyroid tissue over time.
This helps explain why a holistic approach should consider more than the thyroid alone. Immune balance, nutrition, digestion, body condition, ageing and general resilience all contribute to how a dog feels day to day.
Are some dogs more likely to develop hypothyroidism?
Hypothyroidism is most commonly recognised in adult and middle-aged dogs, although older dogs can be affected too.
Certain breeds appear more frequently in veterinary discussions, including:
- Golden Retrievers.
- Labrador Retrievers.
- Dobermanns.
- English Setters.
- Rhodesian Ridgebacks.
That does not mean other breeds or mixed-breed dogs cannot develop an underactive thyroid. The individual dog, their symptoms and their blood-test results matter more than breed alone.
How is hypothyroidism in dogs diagnosed?
A proper diagnosis usually involves looking at your dog's symptoms alongside their blood-test results.
You might hear your vet mention total T4, free T4 and TSH. These names sound technical, but the basic idea is straightforward: each result helps build a more complete picture of how the thyroid is functioning.
| Test | What it tells your vet | Why context matters |
|---|---|---|
| Total T4 | Measures the overall amount of circulating thyroxine. | Can be affected by illness, some medications, age and breed. |
| Free T4 | Measures the portion of thyroid hormone that is not bound to proteins. | Can help clarify whether a low total T4 reflects true thyroid dysfunction. |
| TSH | Measures the signal telling the thyroid to produce more hormone. | Often rises when thyroid function is low, but a normal result does not automatically rule out hypothyroidism. |
Can a low T4 result mean something other than hypothyroidism?
Yes. This is an important point.
A low total T4 result on its own does not always mean a dog has an underactive thyroid. Other illnesses, physical stress and certain medications, including some steroid medications, can temporarily lower thyroid readings.
Your vet may recommend further thyroid testing or repeating blood work when your dog is otherwise stable.
Looking at the whole dog helps avoid both missed diagnoses and unnecessary treatment.
Does my dog need thyroid medication?
If your dog has confirmed hypothyroidism, your vet may prescribe a thyroid hormone replacement such as levothyroxine.
This medication replaces hormone the thyroid gland is no longer producing in adequate amounts. For many dogs, it is an important part of long-term management.
Herbal support and veterinary medication do not need to be presented as opposing choices. Often, the most sensible approach is to use appropriate veterinary treatment while supporting your dog's diet, energy, skin, coat, comfort and general wellbeing.
Please do not stop, reduce or replace prescribed thyroid medication without speaking with your veterinarian. If your dog is taking thyroid medication and you introduce herbal support, regular monitoring helps your vet decide whether any adjustment is appropriate.
How quickly does thyroid medication work in dogs?
Every dog is different. Some dogs begin to look brighter once their medication plan is established, while coat regrowth, skin changes and weight management can take longer.
Your vet will usually recommend follow-up blood testing after treatment begins and then ongoing checks once your dog's levels are stable.
Try not to judge progress by one symptom alone. Energy, coat condition, body weight, enthusiasm for walks and general comfort all help tell the story.
What should a dog with hypothyroidism eat?
There is no single magic food that fixes an underactive thyroid. However, a balanced, appropriate diet can make a real difference to how a dog feels and how easy it is to manage their weight and overall condition.
Prioritise quality protein
Dogs need adequate protein to help maintain muscle, support normal skin and coat renewal, and feel satisfied after meals.
Depending on your dog's individual needs, this may include a nutritionally balanced fresh-food diet, a properly formulated cooked diet or another complete and balanced food recommended by your vet.
Keep an eye on portions
Dogs with a slower metabolism can gain weight even when their meals have not changed.
Measure meals rather than guessing, account for treats and review your dog's body condition regularly. If weight loss is needed, work with your vet on a realistic plan rather than making sudden, drastic cuts.
Support healthy skin and coat
Adequate protein, essential fatty acids and balanced nutrition all help support normal skin and coat health.
Small amounts of dog-appropriate oily fish may be suitable for some dogs, but dietary changes should always reflect the dog's individual medical history, digestive tolerance and energy needs.
Avoid randomly adding large amounts of iodine
Iodine is involved in normal thyroid hormone production, but more is not automatically better.
Adding concentrated seaweed, kelp or iodine products without professional guidance can create an unbalanced intake, especially if your dog is already eating a complete diet or taking a thyroid-support formula containing bladderwrack.
My practical approach: focus on balanced meals, adequate protein, sensible portions and consistency. A dog with hypothyroidism needs steady support, not an endless collection of unregulated additions to the food bowl.
Practical ways to support a dog with an underactive thyroid
Thyroid support is rarely about one dramatic change. It is usually the small, consistent things that help a dog feel more comfortable and supported over time.
Keep exercise gentle and regular
Short, enjoyable walks are often more manageable than pushing a tired dog through a long outing. Build activity gradually and pay attention to how your dog feels afterwards.
Make warmth easy to find
Dogs with low thyroid function may seek warmth more often. A comfortable bed away from cold floors, draughts and damp weather can make a noticeable difference.
Look after the skin and coat
Gentle brushing, appropriate bathing and prompt attention to recurring skin or ear concerns can help keep your dog more comfortable while the underlying issue is being managed.
Track more than body weight
Keep notes on energy, appetite, coat condition, stools, walking distance and sleep. These everyday details are useful when discussing progress with your veterinarian.
Keep meals and medication consistent
Follow your vet's instructions about how and when to give thyroid medication. Consistent routines make it easier to assess whether your dog's plan is working.
Do not overlook sore joints
Weight gain and reduced activity can place extra strain on movement. If your dog seems stiff, reluctant to climb stairs or slower getting up, discuss joint support and comfort with your vet.
Formulated for dogs
Why I created Hypothyroid Support
A dog with an underactive thyroid is not simply a dog with a number out of range on a blood test.
They may also feel tired, struggle with weight, lose coat condition, become less mentally bright and need additional support as they age.
I created Hypothyroid Support to provide targeted traditional herbal and nutritional support for healthy thyroid function, normal metabolism, immune balance, vitality and overall wellbeing.
The formula brings together six carefully selected herbs, each chosen to support a different part of the bigger picture.
Shop Hypothyroid SupportWhat does Hypothyroid Support help support?
- Normal thyroid and endocrine function.
- Healthy metabolic processes.
- Everyday energy and vitality.
- Normal immune system balance.
- Healthy circulation and general wellbeing.
- Mental alertness and resilience.
- Skin and coat wellbeing as part of a whole-body care plan.
- Comfort and quality of life alongside appropriate veterinary care.
It is Australian made, formulated by a Small Animal Naturopath and prepared in a naturally flavoured vegetable-glycerine base that can be mixed into food.
The herbs in Hypothyroid Support and why I chose them
I do not believe in throwing herbs together just because they sound impressive. Each ingredient in Hypothyroid Support has a specific place within the broader picture of thyroid, metabolic and whole-body wellbeing.
Astragalus
Traditional support for immune balance and vitality.
Astragalus has a long history of use in traditional herbal medicine to support normal immune function, resilience and general wellbeing.
Because immune-related changes can play a role in some cases of canine hypothyroidism, I included astragalus to support the whole dog rather than focusing on the thyroid in isolation.
Bladderwrack
Traditional nutritional support for thyroid wellbeing.
Bladderwrack is a sea vegetable naturally containing iodine and other trace nutrients associated with normal thyroid function.
It is included as one carefully selected component of the formula. Because iodine intake needs to remain balanced, additional concentrated kelp or iodine supplements should not be added without veterinary guidance.
Siberian ginseng
Traditional support for stamina, resilience and vitality.
Siberian ginseng is traditionally used to help the body adapt to everyday physical and environmental demands.
For dogs that have become flat, less enthusiastic or less active, it contributes gentle whole-body support for normal energy and resilience.
Bacopa
Traditional support for the nervous system and mental alertness.
Bacopa is traditionally associated with cognitive wellbeing and a balanced nervous system.
It is included because dogs with low thyroid function can sometimes seem mentally flat, less engaged or simply not quite themselves.
Coleus
Traditional support for healthy metabolism and endocrine function.
Coleus is included for its traditional use in supporting normal metabolic processes and thyroid wellbeing.
It contributes to the formula's broader focus on healthy energy, metabolism and everyday vitality.
Ginger
Traditional support for circulation, digestion and warmth.
Ginger has a long history of use in traditional herbal medicine to support healthy circulation, digestive comfort and general vitality.
It is particularly relevant for dogs that seem sluggish, feel the cold or have lost some of their usual enthusiasm.
How much Hypothyroid Support should I give my dog?
Shake the bottle well before use and give the recommended amount twice daily.
Dogs up to 25 kg: give one drop per kilogram of body weight, twice daily.
Dogs over 25 kg: start with 25 drops, then add one additional drop for every extra 2 kg of body weight, twice daily.
Syringe guide: 0.5 ml is approximately 10 drops, and 1 ml is approximately 20 drops.
| Dog's weight | Amount per dose | How often |
|---|---|---|
| 5 kg | 5 drops | Twice daily |
| 10 kg | 10 drops, approximately 0.5 ml | Twice daily |
| 20 kg | 20 drops, approximately 1 ml | Twice daily |
| 25 kg | 25 drops | Twice daily |
| 35 kg | 30 drops, approximately 1.5 ml | Twice daily |
Use the calibrated syringe provided and mix the formula into your dog's food. If your dog is particularly fussy, try a small amount of wet food, an appropriate treat or another dog-safe food they enjoy.
For dogs with sensitive stomachs, introducing the formula gradually can make the adjustment easier. Follow the product label and speak with your veterinarian if your dog has other health conditions or takes regular medication.
You can also use the dosage calculator on the Hypothyroid Support product page to check the amount for your dog's weight.
Important safety considerations
- Do not use for an overactive thyroid. Hypothyroid Support is intended for slow thyroid support and is not appropriate for hyperthyroidism.
- Continue veterinary monitoring. Dogs receiving thyroid medication should have their thyroid levels reviewed as recommended by their vet.
- Never adjust prescription medication yourself. Any changes must be made by your veterinarian.
- Use caution with blood-thinning medications. Ask your vet before starting the formula if your dog takes these medicines.
- Stop before planned surgery or anaesthesia. Discontinue at least two weeks before a scheduled procedure unless your veterinarian advises otherwise.
- Do not add extra concentrated iodine or kelp without advice. The formula already contains bladderwrack.
- Seek veterinary advice if your dog becomes unwell. If symptoms worsen or your dog does not improve, stop the product and consult your veterinarian.
What are other dog owners saying?
Hearing from someone who has been through similar changes with their own dog can be reassuring, particularly when the first signs are tiredness, thinning fur and a dog that just does not seem quite right.
★★★★★
More energy and early signs of coat regrowth
Denise explained that her little dog had been losing fur, but after a few weeks on Hypothyroid Support she noticed some new fur coming through and felt he had more energy.
Denise Marsden
Hypothyroid Support customer
★★★★★
Charlie's whole-body support routine
Brian shared that his dog Charlie had been using Hypothyroid Support alongside Skin Allergy Support, Adrenal Support and Joint Support, and was feeling great after several months.
Brian Callinan
Natural Pet Supplements customer
Other ways to support the whole dog
A dog with thyroid concerns may also need additional support for skin condition, liver wellbeing, movement or general vitality.
Which products are appropriate depends on the individual dog, their symptoms, their medication and your veterinarian's recommendations.
Liver Support
Provides traditional St Mary's thistle support for healthy liver function, normal metabolic processes and overall wellbeing.
Shop Liver Support
Mobility Joint Support
Supports healthy joints, connective tissue and everyday movement, particularly when weight gain or reduced activity is placing extra demands on comfort.
Shop Mobility Support
Skin Allergy Support
Supports healthy skin comfort, normal immune function and coat wellbeing for dogs experiencing ongoing skin sensitivity.
Shop Skin SupportHelpful to know: if you are considering more than one herbal product, check the individual cautions and speak with your veterinarian if your dog takes prescription medication or has multiple medical conditions.
Frequently asked questions about hypothyroidism in dogs
What are the first signs of hypothyroidism in a dog?
Early signs often include lower energy, unexplained weight gain, a dull coat, thinning fur and less enthusiasm for exercise. Some dogs also seek warmth more often or develop recurring skin concerns. These symptoms can overlap with other conditions, so veterinary assessment is important.
Can hypothyroidism cause hair loss in dogs?
Yes. A thinning coat, slow regrowth after clipping, increased shedding and a sparse tail can all be associated with low thyroid function. Hair loss can also have other causes, including skin conditions, nutritional concerns and other hormonal imbalances.
Can an underactive thyroid make a dog gain weight?
Yes. Thyroid hormones help regulate metabolism, so reduced thyroid function can make weight gain more likely. If your dog is gaining weight despite eating a similar amount, ask your vet whether thyroid testing would be appropriate.
Why is my dog tired, gaining weight and losing fur?
That combination can occur with hypothyroidism, but it can also appear with other medical conditions. Your veterinarian can review your dog's symptoms and recommend suitable blood tests, which may include total T4, free T4 and TSH.
Can hypothyroidism in dogs be managed naturally?
Good nutrition, sensible exercise, appropriate herbal support and lifestyle adjustments can all contribute to a dog's overall wellbeing. However, confirmed hypothyroidism may require prescription thyroid hormone replacement. Natural support should complement veterinary care, not replace medication that your dog needs.
Can my dog take Hypothyroid Support with thyroid medication?
If your dog takes thyroid medication, speak with your veterinarian before introducing any herbal supplement. Your vet can assess whether the formula is suitable and recommend appropriate monitoring. Do not alter your dog's prescription dose yourself.
Is Hypothyroid Support suitable for hyperthyroidism?
No. Hypothyroid Support is intended for dogs needing support for an underactive thyroid. It must not be used for an overactive thyroid. Hyperthyroidism and hypothyroidism are different conditions and require different management.
Does Hypothyroid Support contain iodine?
The formula contains bladderwrack, a sea vegetable that naturally contains iodine. Because iodine intake should remain balanced, avoid adding separate concentrated iodine, kelp or seaweed products unless your veterinarian recommends them.
How long does it take to notice a difference?
Every dog responds differently. Energy and general wellbeing may change before skin, coat or body condition do. Herbal support is intended as part of a consistent routine rather than a quick fix, and progress should be reviewed alongside veterinary monitoring.
What foods should dogs with hypothyroidism avoid?
There is no universal list of forbidden foods for every dog with hypothyroidism. Focus on a complete and balanced diet, appropriate portions and avoiding unnecessary concentrated iodine supplements. Your veterinarian can advise if your dog has other dietary needs, allergies or medical conditions.
Does hypothyroidism make dogs feel cold?
It can. Thyroid hormones help regulate metabolism and body temperature, so some dogs with low thyroid function become more interested in warm beds, sunny spots and blankets than they used to be.
Can low thyroid affect a dog's behaviour?
Dogs with an underactive thyroid may seem quieter, less mentally alert, less interested in play or generally flat. Behaviour changes should always be assessed in context, as pain, stress and other medical conditions can also influence how a dog behaves.
Is hypothyroidism the same as Cushing's disease?
No. Hypothyroidism involves insufficient thyroid hormone, while Cushing's disease involves excessive cortisol activity. Some symptoms, including coat changes and altered body condition, can overlap, which is why the correct veterinary testing is important.
Can hypothyroidism cause recurring skin or ear problems?
Low thyroid function can be associated with changes in the skin and coat, and some dogs experience recurring skin concerns. However, allergies, yeast, environmental triggers and other underlying issues can also contribute, so ongoing problems should be assessed by your vet.
Is Hypothyroid Support easy to give?
Yes. The liquid formula has a natural bacon flavour and can be mixed into your dog's food. A calibrated syringe is included to make measuring the recommended amount easier.
Is Hypothyroid Support made in Australia?
Yes. Hypothyroid Support is formulated by Small Animal Naturopath Erin Follington and made in Australia using carefully selected human-grade herbal ingredients.
The most important thing to remember
A diagnosis of hypothyroidism does not mean your dog cannot enjoy a comfortable, happy life.
The best approach is usually a balanced one: get the diagnosis right, follow your vet's recommendations, support your dog's nutrition and comfort, and pay attention to the everyday changes that show how they are really feeling.
Whether your dog needs support with energy, coat condition, metabolism or general resilience, small consistent steps can make their routine feel much more manageable.
And if you are not sure where to start, you do not have to figure it all out on your own.
Shop Hypothyroid Support Meet ErinRelated articles from the Pet Health Library
Veterinary references and further reading
- American Animal Hospital Association: Canine Hypothyroidism.
- American Animal Hospital Association: Canine Hypothyroidism Diagnostic Testing and Monitoring.
- American Animal Hospital Association: Canine Hypothyroidism Therapy.
- Cornell University College of Veterinary Medicine: Thyroid Testing Interpretation.
- Merck Veterinary Manual: Hypothyroidism in Animals.
About the author
Erin Follington
Small Animal Naturopath & Founder of Natural Pet Supplements
I created Natural Pet Supplements to give dog and cat owners access to thoughtfully formulated, Australian-made herbal and nutritional support.
My approach combines traditional herbal knowledge, practical nutrition and a genuine understanding that every animal is an individual.
From our base in Perth, Western Australia, each formula is designed to support everyday wellbeing while working alongside appropriate veterinary care.
Learn more about Erin
