How to keep your dog's immune system strong

Rufus is usually an enviable picture of health, especially when he’s charging into the river for a swim or chasing his rugby ball. A dog’s immune system is their built-in defence team, a 24/7 network of cells, tissues and organs that protects them from viruses, bacteria, parasites and even some cancers. When it’s running well, we don’t notice it; they bounce back quickly from the odd sniffle, heal fast from scrapes and stay full of life. But when it’s under pressure, things can start to slip; more infections, slower healing, allergies that flare up or simply less zest for play.

A robust immune system isn’t just about dodging illness. It’s also about helping your dog age well, stay active and enjoy life to the fullest. And while genetics play a role, diet, lifestyle and environment have a huge influence which means we have more control than we might think.

Nutrition as the foundation of immunity

If you want your dog’s immune system to work at its best, start with their bowl. The food you choose literally becomes the raw material for every immune cell in their body. And while there’s no single “superfood” that can make your dog invincible, the right balance of nutrients can keep their defences strong year-round.

Protein power

Immune cells are made from protein, or more precisely, from the amino acids that make up protein. High-quality, bioavailable protein from sources like meat, fish or eggs helps your dog produce antibodies, repair damaged tissue and keep white blood cells healthy. Poor-quality protein, on the other hand, forces their body to work harder to get the building blocks it needs.

Healthy fats 

Not all fats are created equal. Omega-3 fatty acids, found in fish like salmon and herring, as well as in some plant oils, are proven to reduce chronic inflammation and help regulate immune responses. This matters because a constantly “on” immune system can burn itself out, leaving your dog more vulnerable over time. Omega-3s also support skin health, which is your dog’s first line of defence against pathogens.

Vitamins and minerals

When it comes to your dog’s immune system, the small things can make a big difference. Vitamins and minerals may only be needed in tiny amounts but they have outsized effects on your dog’s ability to fight off illness and recover quickly. Without them, immune responses can be sluggish, incomplete or overactive in ways that cause harm.

• Vitamin C isn’t just for when we get a cold. While dogs can produce some of their own, extra dietary vitamin C can give their immune system a boost especially during periods of stress, illness or intense activity. It acts as a potent antioxidant, neutralising free radicals before they can damage immune cells or the tissues they’re protecting.
• Vitamin E works in tandem with Vitamin C, protecting cell membranes (including those of white blood cells) from oxidative stress. A well-protected immune cell is one that can react swiftly when it’s needed.
• Zinc is essential for the development and activation of immune cells like T-lymphocytes. It’s also involved in wound healing and skin health and since skin is the body’s largest immune barrier, zinc deficiency can open the door to infections.
• Iron ensures that oxygen is delivered efficiently throughout the body, including to immune cells. Without enough oxygen, these cells can’t function at full capacity, leaving the immune response weaker and slower.

Getting these micronutrients from whole food sources like liver, beef, fish and certain vegetables means they come packaged with other beneficial compounds, often making them easier for your dog’s body to absorb and use.

Antioxidants for cell protection

Antioxidants, found in colourful vegetables and berries, help neutralise free radicals; unstable molecules that damage cells and speed up ageing. They also protect the immune cells themselves from oxidative stress, keeping them active and responsive.

Whole foods for whole-body health

You don’t need to feed your dog a raw kale salad but adding whole food ingredients to their diet such as pumpkin, broccoli, blueberries or liver can deliver a rich spectrum of immune-supporting compounds. Many of these foods also contain phytonutrients, natural plant chemicals that have anti-inflammatory and antimicrobial effects.

Supplements with immune-supporting evidence

Even with a balanced diet, some dogs can benefit from targeted supplements especially if they have specific health challenges, are recovering from illness or are entering their senior years when the immune system naturally begins to slow. The key is choosing supplements with research behind them, not just marketing hype.

Brewer’s yeast

Brewer’s yeast is often included in dog supplements for its rich B-vitamin profile, which supports energy production and healthy skin. But one of its lesser-known benefits is that it’s a natural source of selenium the trace mineral that plays a crucial role in immune signalling and antioxidant defence. There’s emerging evidence that selenium may help regulate IGF-1, a growth hormone linked to longevity in dogs, particularly large breeds. By keeping IGF-1 at healthier levels, selenium could help protect against age-related decline while maintaining a robust immune system.

Bone broth

A slow-cooked bone broth delivers amino acids, collagen and minerals in an easily digestible form. These amino acids help repair tissues damaged by infection or inflammation, while collagen supports gut health and a healthy gut is a cornerstone of immune function. In fact, up to 70% of immune cells reside in the gut, so keeping the digestive tract strong is a direct way to keep your dog’s defences strong too.

Medicinal mushrooms 

Varieties like Reishi and Lion’s Mane are rich in beta-glucans, complex polysaccharides that can “train” immune cells to respond more efficiently. Unlike a stimulant, which pushes the immune system into overdrive, beta-glucans help the body strike the right balance, ramping up when faced with pathogens and calming down when the threat has passed. This modulation is especially valuable in preventing chronic inflammation, which can wear down immunity over time.

Fish oils 

The omega-3 fatty acids EPA and DHA, found in fish like salmon and herring, are widely known for supporting heart and brain health. But they also help regulate the immune system by reducing low-grade inflammation and supporting the integrity of cell membranes, including those of immune cells.

Kelp

Kelp is a natural source of iodine, which supports thyroid function and the thyroid gland plays a surprisingly large role in regulating immune health. A healthy thyroid keeps metabolism, hormone balance and immune responsiveness running smoothly.

Pumpkin and broccoli 

Both vegetables are rich in antioxidants like beta-carotene and sulforaphane, which protect cells from oxidative damage. Their natural fibre content also supports a healthy gut microbiome, which, in turn, boosts immune efficiency.

Lifestyle factors that strengthen immunity

A strong immune system isn’t built on nutrition alone, your dog’s daily habits and environment also play a huge role. Just as in humans, stress, poor sleep or a sedentary lifestyle can wear down a dog’s defences, leaving them more vulnerable to illness. The good news? Small, consistent lifestyle changes can have an outsized impact on keeping their immune system in top form.

Regular exercise that’s right for their age

Movement is essential for immune health because it stimulates circulation, helping immune cells travel quickly to where they’re needed. It also supports a healthy weight, which reduces inflammation throughout the body. Puppies benefit from short, frequent play sessions that don’t overtax their developing joints; adult dogs need a balance of walks, free running and mental challenges; and seniors do best with gentler but still regular activity to keep muscles and joints working smoothly.

Plenty of quality sleep

Dogs need more sleep than humans; anywhere from 12 to 18 hours a day, depending on age and breed. Sleep is when the body does much of its repair work, including bolstering immune function. A comfortable, quiet sleeping space and a predictable daily rhythm can improve sleep quality, helping the immune system stay alert when it matters most.

Stress reduction and emotional security

 Chronic stress can suppress immune function, making dogs more prone to illness. Sources of stress vary – loud environments, inconsistent routines or separation anxiety – but the solutions often start with predictability and reassurance. Regular routines, gentle training methods and safe spaces where your dog can retreat all contribute to emotional balance and stronger immunity.

Mental stimulation

Boredom and under-stimulation can be stressful for dogs, even if it doesn’t look like it on the surface. Training sessions, puzzle toys, scent games and varied walking routes all engage the brain and mental engagement helps keep stress hormones in check, which in turn supports immune health.

A clean but not sterile environment

While it’s important to maintain hygiene especially for food and water bowls, bedding and high-traffic areas over-sanitising can limit a dog’s exposure to the harmless microbes that help “train” their immune system. Regular outdoor time, contact with varied environments and interaction with other healthy dogs can all support a resilient immune response.

Protecting against immune system challenges

Even the strongest immune system can be undermined if it’s constantly battling avoidable threats. Supporting your dog’s immunity isn’t just about what you add, it’s also about what you remove or manage in their environment.

Vaccinations & parasite control

Core vaccinations and parasite prevention are essential tools for protecting against serious and sometimes life-threatening, diseases. But more isn’t always better; excessive chemical parasite treatments can place unnecessary stress on the immune system. A good vet will help you tailor a schedule based on your dog’s age, lifestyle and local risk factors. This personalised approach means your dog is protected without being overexposed to medications they don’t need.

Minimising toxins in daily life

Dogs live close to the ground, lick their paws and explore the world with their noses which means they’re often more exposed to environmental toxins than we are. Household cleaning products, cigarette smoke, lawn pesticides and even some scented candles can all release chemicals that place extra strain on the immune system. Switching to pet-safe cleaning products, avoiding smoking indoors and being mindful of where and when your dog plays outside (especially after lawn treatments) can make a big difference over the long term.

Early detection through regular checks

Many immune-impacting illnesses from tick-borne diseases to autoimmune conditions respond better when caught early. Routine vet visits aren’t just about vaccinations; they’re an opportunity for a full health check, blood work if needed and discussions about any subtle changes you’ve noticed. Catching a problem early means the immune system isn’t fighting with its back against the wall and your dog has the best possible chance of recovery.

Immune health across life stages

A dog’s immune system isn’t static it changes as they grow, mature and age. Knowing what each stage needs means you can give targeted support, helping them stay healthy at every age.

Puppies 

In their first months, puppies’ immune systems are still developing. They’re born with temporary protection from their mother’s antibodies (if she was vaccinated or exposed to certain diseases) but this fades within weeks. That’s why early nutrition is so important; high-quality food rich in protein, healthy fats and essential micronutrients fuels the growth of immune cells and tissues.

Gentle exposure to new sights, sounds, people and other healthy dogs during their socialisation window also helps train their immune system to respond appropriately to the world around them. Balance is key: too little exposure and they may be overly sensitive later; too much, too soon, can overwhelm their defences.

Adult dogs 

By the time your dog reaches adulthood, their immune system is in full working order but that doesn’t mean it runs on autopilot. Stress from busy family life, travel or changes in routine can still affect immunity.

This is the time to maintain a balanced diet, regular exercise and parasite prevention, while also staying alert to subtle shifts in behaviour or energy that could indicate early health issues. Adult dogs benefit from ongoing mental and physical stimulation, which helps regulate stress hormones and keeps their immune defences strong.

Senior dogs 

As dogs age, their immune systems naturally slow down, making them more vulnerable to infections, slower to heal and more prone to chronic inflammation. This stage calls for nutrient-dense diets rich in antioxidants, omega-3 fatty acids and easily digestible protein to counteract muscle loss and support immune cell function.

Gentle but regular exercise helps maintain circulation, while keeping stress levels low is especially important. Senior dogs may also need more frequent vet checks to catch and address immune-impacting illnesses early.

Building lasting resilience from the inside out

Your dog’s immune system is their frontline defence against illness and like any defence, it works best when it’s consistently supported rather than only called upon in a crisis. The right diet, rich in key micronutrients and antioxidants, lays the foundation. Thoughtful use of high-quality supplements can help fill nutritional gaps, while an active, low-stress lifestyle keeps immune defences sharp.

Just as important is removing unnecessary burdens: minimising environmental toxins, avoiding over-medication and catching potential problems early through regular vet care. And because immune needs change over a lifetime, adapting your approach for puppies, adults and seniors ensures your dog gets the right kind of support at the right time.

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