What Supplements Should I Add to My Dog’s Diet? Types, Benefits and When to Use Them

By Dr Duncan Houston

Quick Answer

Dogs may benefit from supplements such as omega-3 fatty acids, probiotics, joint support, vitamins, and minerals depending on their diet, life stage, and health status. Supplements should support a balanced diet, not replace it.

As a veterinarian, I use supplements to fill nutritional gaps, support specific health conditions, and optimise long-term wellbeing, but only when they are actually needed.

Walk into any pet store and you will see shelves full of supplements.

Oils, powders, chews, capsules. All promising better health, shinier coats, stronger joints, and longer lives.

Some are useful. Some are unnecessary. And some are used incorrectly.

The key is understanding what each supplement does and when it actually adds value.

The Most Important Rule: Supplements Support, Not Replace

Before adding anything, the base diet matters most.

• A balanced diet should provide the majority of nutrients

• Supplements are used to fill gaps or target specific needs

• Adding random supplements to an unbalanced diet does not fix the problem

Think of supplements as fine-tuning, not the foundation.

Common Types of Dog Supplements

Omega-3 Fatty Acids

One of the most widely beneficial supplements.

Common sources:

• Fish oil

• Marine oils

Benefits include:

• Improved skin and coat health

• Reduced inflammation

• Joint support

• Heart and brain health

Most dogs benefit from omega-3 supplementation, especially if their diet is low in fish.

Probiotics

Probiotics support the gut microbiome.

They help:

• Improve digestion

• Support nutrient absorption

• Stabilise stool quality

• Support immune function

They are particularly useful:

• During diet changes

• In dogs with sensitive stomachs

• After antibiotics

Probiotics are one of the simplest and most effective additions to most diets.

Joint Supplements

Used to support mobility and joint health.

Common ingredients include:

• Glucosamine

• Chondroitin

• Green-lipped mussel

• MSM

Benefits:

• Support cartilage health

• Reduce joint inflammation

• Improve comfort in aging or active dogs

Often used in large breeds, senior dogs, or dogs with arthritis.

Vitamin and Mineral Supplements

These are essential in some situations.

Used when:

• Feeding a fully home-cooked diet

• Addressing known deficiencies

• Supporting specific medical conditions

They ensure:

• Proper nutrient balance

• Prevention of long-term deficiencies

These should not be guessed. Balance is critical.

Calcium Supplements

Important in specific cases.

Needed when:

• Feeding home-prepared diets without bone

• Supporting growth in puppies (only if correctly balanced)

Calcium must always be balanced with phosphorus.

Too much or too little can cause serious problems.

Digestive Enzymes

These help break down food.

They may benefit:

• Dogs with digestive disorders

• Dogs with pancreatic insufficiency

• Some dogs with chronic gut issues

Not every dog needs them, but they can be helpful in specific cases.

Skin and Coat Supplements

Often combined with omega-3s, but may include:

• Zinc

• Biotin

• Vitamin E

Used for:

• Dry skin

• Dull coat

• Skin barrier support

Often secondary to correcting the base diet.

Calming Supplements

Used for behavioural support.

Common ingredients:

• L-theanine

• Casein-based compounds

• Herbal blends

May help:

• Mild anxiety

• Stress-related behaviours

• Environmental adjustment

Best used alongside behaviour training, not as a sole solution.

Multivitamins

Used to cover potential gaps.

Most useful when:

• Diet quality is uncertain

• Feeding is inconsistent

• Additional nutritional support is needed

Not always required for dogs on a well-balanced commercial diet.

When Should You Add Supplements?

Supplements are most useful when:

• Feeding a home-cooked or raw diet

• Managing a medical condition

• Supporting aging or high-performance dogs

• Addressing specific deficiencies

• Improving skin, coat, or gut health

They should always have a purpose.

Common Mistakes to Avoid

• Adding multiple supplements without understanding overlap

• Using human supplements

• Over-supplementing

• Ignoring the base diet

• Guessing doses

More is not better. Balance is everything.

How to Tell If Supplements Are Helping

Look for:

• Improved stool quality

• Better coat condition

• Stable energy levels

• Improved mobility

• Overall wellbeing

If nothing changes, the supplement may not be necessary.

Final Thoughts

Supplements can be incredibly useful when used correctly.

But they are not a shortcut. A well-balanced diet always comes first, and supplements should only be added with a clear purpose.

The best approach is simple, targeted, and consistent.

FAQs

Does my dog need supplements if they eat kibble?
Not always. Many complete diets already contain balanced nutrients, but some dogs may still benefit from targeted additions like omega-3s or probiotics.

Are probiotics worth it for dogs?
Yes. They are one of the most useful and widely beneficial supplements, especially for gut health and digestion.

Can I give my dog multiple supplements at once?
Yes, but only if they are appropriate and do not overlap. It is best to keep supplementation simple and targeted.

If you are unsure which supplements your dog actually needs, tracking diet, stool, energy, and health changes can help identify gaps. The ASK A VET™ app can help you review your dog’s diet and build a more targeted supplementation plan.