What You Need To Know About Your Dog’s Immune System

Key Points

  • Your dog's immune system consists of critical parts to maintain their health.

  • A nutrient-rich diet and regular exercise help keep your dog's immune system in top shape.

  • There are many diseases your dog can get; knowing the symptoms is important to their long-term care.

You know better than anyone about your dog's health, But do you know how your dog's immune system keeps them healthy? They can't tell you how they feel or tell you when they're sick, so it's hard to determine when they're looking at you with (literal) puppy eyes if they need something or aren't feeling well.

You love your canine friends, so you want to make sure to keep them as healthy as possible. If you don't know about the critical function of your dog's immune system, you may be playing a guessing game about your dog's well-being.

Dog and owner run at beach

In the Beginning

The lifelong fight against infection and disease starts while your pet is still in their mother's womb. The mother's antibodies protect her puppies against disease and infection for the first few months until it's time to get vaccinated.

The mother's milk is also full of antibodies and nutrients to support the puppy's developing immune system. As they grow and are weaned off mom's milk, they develop their natural defenses. As they age, their immune system weakens and isn't able to fight off infection and disease as easily as when they were younger.

Your dog must have regular vet checkups. It is also important you understand your dog's immune system and how it develops so you can better protect them and keep them healthy for as long as possible.

Your Dog's Immune System

Organs like the lymph nodes, spleen, thymus, and bone marrow identify and fight off bad bacteria, infectious disease, and viruses.

It's important to keep your canine companion's health and immune system in good shape to protect them from everyday exposures, including parasites and other environmental factors.

Providing a balanced diet and making sure they get enough exercise and mental stimulation goes a long way to maintain their health. Avoid exposure to potentially harmful hazards, toxic substances, and extreme temperatures.

Types of Immune System Diseases

Immune system diseases occur when a dog's natural defenses break down and are weakened. Diseases can range from mild to extreme. These include allergies, infections, and immune system disorders.

Allergies are when a dog's immune system overreacts to environmental factors and causes itching, sneezing, and dry skin.

Infections are when a virus, bacteria, or other pathogen compromises the immune system.

Autoimmune disorders are when the body fights against itself by attacking the host's cells or tissues.

These and other diseases like cancer, disease in organ systems, and nutritional deficiencies weaken the immune system and increase the risk of infection. Knowing the signs to look for when your pup is sick is challenging but necessary if you want to pinpoint a potential problem.

Tell-tale signs of a possible immune system problem include:

  • A change in appetite or weight

  • Tiredness or lethargy

  • Skin irritation or infection

  • Excessive thirst or bathroom breaks to pee

  • Poor coat condition

  • Coughing, sneezing, or other respiratory changes

  • Vomiting

  • Diarrhea

  • Weakness or limping

  • Lumps or bumps on the body

  • Mental dullness

Dog and man give high five

Other Systems With Immune Functions

There are other ways a dog's immune system can help them thrive and stay healthy.

The digestive system is an integrated part of the body that helps break down and absorb nutrients the body needs. It's a complex process that starts when food is placed in the mouth and ends when the nutrients are used by the body.

The digestive system has many organs that break down food so it can be absorbed and used for energy, growth, and repair. It also eliminates unnecessary waste.

The respiratory system not only allows dogs, cats, and humans to breathe but also protects from breathing a multitude of problems, ranging from minor illnesses to serious conditions. This network of organs filters out irritants from the air and ensures air is safe to breathe.

The urinary system is responsible for removing toxins, waste, and other unwanted substances from the body. Its organs include the kidneys, ureters, bladder, and urethra which work together to ensure the body functions properly.

Kidneys filter waste and the bladder transports the waste out as urine. This is one of the more important systems in all animals for mitigating illness.

Another essential part of the immune system is the circulatory system. You may think this system has no bearing on your immune system, but it does play a role in regulating temperature, removing waste, and strengthening the body's overall immunity.

Innate & Adaptive Immune Systems

The canine immune system is complicated and divided into two sub-parts: the innate and the adaptive immune systems. 

The innate immune system is the first line of defense for protecting your dog. It’s also a two-part system. The physical barriers include the skin and mucous membranes. Chemical barriers are made of enzymes, antibodies, and cytokines.

The adaptive immune system is the second line of defense against disease and infection. It's made up of cells and molecules that respond to different foreign bodies.

When these cells and molecules detect an invader, the adaptive system kicks in and produces antibodies. These antibodies attach to the invading illnesses and fight to eliminate them.

Happy dog in grass

How the Immune System Fights Common Diseases

There are many diseases out there that affect your pet's immune system and overall health. Here are some of the more common serious illnesses and their symptoms:

Canine Parvovirus

Canine parvovirus, also known as Parvo or CPV, is a highly contagious disease. This disease uses up the body's white blood cell count and can make it difficult for your dog to fight off infections or illnesses.

Symptoms include:

  • Bloody diarrhea

  • Vomiting

  • Lethargy

  • Fever

This is a serious and potentially fatal disease. It’s especially serious in puppies and younger dogs. Call your vet immediately if your dog has any of these symptoms.

Canine Distemper

Distemper affects the dog's respiratory system, gastrointestinal tract and nervous system. The virus produces the following symptoms:

  • Coughing

  • Nasal discharge

  • Fever

  • Vomiting

  • Diarrhea

Distemper also affects the immune system by using up the body's white blood cells, making it difficult for your dog to fight off infections and illness.

Husky with broccoli

Kennel Cough

Kennel cough is a highly contagious upper respiratory disease caused by several types of bacteria and viruses.

If you come in contact with a dog that has kennel cough and you have dogs at home, immediately throw your clothes in the washer and thoroughly wash your hands to prevent spreading it to your pet.

Symptoms are:

  • Honking-like cough

  • Sneezing

  • Nasal discharge


Leptospirosis, also known as Lepto, is a very serious bacterial infection that dogs can pick up from just about anywhere. It is spread via the urine of infected animals. The most common way it is spread is from your dog sharing water with outdoor critters such as raccoons.

This is another disease that requires immediate vet care to prevent dehydration and complications such as inflammation of the heart tissues which can cause long-term damage if not treated. The symptoms and complications of Lepto include:

  • Fever

  • Vomiting

  • Diarrhea

  • Decrease in appetite

  • Coughing

  • Bleeding

  • Jaundice

  • Kidney failure

How to Keep Your Dog Healthy

There are ways to set your dog up for success in their battle with illness and infection.

First, be aware of the symptoms of these diseases so action is taken before the immune system is weakened.

Vaccinations and boosters are preventive measures that cause antigenic stimulation, which means they produce an immune response against a foreign substance like bacteria or virus. Vaccinations and boosters are the best way to protect your dog from any disease or infection.

Exercise, a healthy diet, and regular visits to the vet for checkups also keep your dog healthy.


There are many questions about your dog's immune system and how it works to protect your pet. A few of those include:

Is a Canine's Immune System Stronger Than a Human's? Than a Cat's?

A 2019 study by a team of researchers from the Global Health and Tropical Medicine and other Portuguese health agencies found the immune system “determines the survival of the individual, discriminating self from non-self. The organism uses multiple defense mechanisms, simultaneously, to ensure the absence of disease. Physical barriers prevent the penetration of invading microorganisms, and the innate immune system has mechanisms of rapid response, such as inflammation, complement system, and antimicrobial molecules, to prevent infection.”

They concluded this proves dogs' and cats' immune systems are just as complex as humans’. Each system is unique in how it's evolved, but it's clear that dogs and cats have just as complex a system as humans.

That said, there are differences because the immune systems developed to react to the environment and needs of the different species. That doesn't mean one is stronger than the other. They have different strengths to meet different needs.

For example, dogs have stronger stomach acid to break down a variety of foods and other substances humans don't consume.

Dogs generally stay at home and rarely have contact with other canines, so they have less exposure to illnesses and less need for strong antiviral protection. Humans have constant exposure to viruses and bacteria from contact with other humans, which has developed a stronger system to fight off illnesses.

Cats seem to be less susceptible to insect-borne diseases than dogs, but it is not known whether that is due to their immune system or other factors.

There are some diseases a dog or cat can get that a human can't, such as distemper. Likewise, humans can contract some diseases — like AIDS — that a dog cannot.

For cats around the world, Feline Immunodeficiency Virus (FIV), often called feline AIDS, is one of the most common infectious diseases. Cats with FIV can become seriously ill from an otherwise harmless virus or bacteria but usually live a normal lifespan unless stricken by a fatal disease such as feline leukemia.

You, your dog, and your cat can share some diseases, from an itchy case of ringworm to the feared and fatal rabies.

What Does a Dog’s Immune System Look Like?

The immune system in dogs involves several organs that work together. The lymphatic system is the central feature of the immune system, transporting white blood cells throughout the body in response to viruses, bacteria, and infections.

Other important components include:

  • Spleen

  • Thymus

  • Skin

  • Mucous membranes

  • Tonsils

The spleen helps filter out unhealthy cells and creates antibodies. The thymus helps by producing cells that function within the immune system.

You don't normally think of skin and mucous membranes as agents of the immune system, but they play a critical role in keeping viruses out and protecting against infection.

Why Do Dog Owners Have a Stronger Immune System?

People with animals are often less stressed and less anxious, which results in a stronger — or less weakened — immune system. Pet ownership is also linked to better social lives and health.

A quick internet search yields numerous articles and reports attesting to the health and immunity benefits of pet ownership.

Owner and dog go for jog

How To Keep Your Dog Healthy

As previously noted, there are a few things you can do to bolster your pet's health. Some are no-brainers; others you might not have considered.

Feed Your Dog a Balanced Diet

Ensure you're giving your dog enough variety and a nutrient-dense diet. Give them the best foods – whether homemade or premade. Avoid any processed food that's high in salt and additive ingredients. Always carefully look at the list of ingredients.

If you're not feeding your dog homemade food, quality kibble is a suitable alternative. The way to know if it's quality kibble is to check to see that one of the first five ingredients is real meat and not meat a byproduct, corn, or other fillers and chemicals.

Filter out any foods that have corn, corn meal, or any other type of "meal." These won't provide nutrient-dense food.

In a 2014 article, Animal Wellness Magazine states, "Around 70% of your dog's or cat’s immune system resides in the gut, so immune cell receptors in the GI tract create an excellent platform for modulating the immune system through diet [ …] A high-quality species-appropriate diet is a good place to start in keeping your dog or cat’s immune system balanced and healthy.”

Keep Your Dog Active

Make sure you and your dog get plenty of exercise to keep both of your immune systems healthy. Spend two or three 30-minute activity sessions with your dog, such as a regular walk.

Supplement Your Dog's Diet

Supplements like fish oil, vitamins, and antioxidants provide essential nutrients for a healthy immune system. There are many types of supplements on the market, so do some research on what food or supplements are good for your dog.

Ask your vet or local holistic store for more information.


There are several parasites dogs can pick up, including fleas, ticks, and worms. Make sure you have a preventive plan with your vet and get your dog regular care, which includes flea collars, vet visits, flea and tick medications, and anything else they might need to keep pests at bay.


Brush your dog's coat and bathe them regularly. Bathing keeps your dog healthy and gives you the chance to check them for skin diseases or parasites. Groomers are experts at caring for a dog's coat and they know what to look for in terms of skincare, etc.

Dog with toothbrush

See Your Vet Regularly

Vet visits allow you and your vet to catch underlying health issues before they get too serious. If you're unsure of anything concerning your dog's health and well-being, reach out to your vet. Develop and maintain a good relationship with your veterinarian. Together you are your dog's healthcare team.

As a member of that team, it is your responsibility to be proactive with the vet. Ask questions, do research, and be armed with knowledge. Advocate for your dog when it's necessary.

Sometimes treatment doesn't work. Don't give up. Continue working with your vet to find the right solution.

Immune Health FTW

Your dog's immune system is made up of several organs that perform essential body functions, including the innate and adaptive immune systems, physical barriers and chemical barriers, and cells and proteins that all share the duty of keeping your dog healthy.

There are common diseases such as kennel cough and parvo that attack your dog’s immune system and cause serious issues. Maintaining a strong immune system through a healthy diet, exercise, hygiene, and vet visits is the best way to fight off these illnesses.

Learning about your dog's immune system can be pretty darn fascinating – as well as keeping your dog healthy. Knowing what to look for, and knowing about common issues such as eye infections in puggles, also serves you well in caring for your dog.

Your pup is a family member, and as such, deserves the best care and attention possible. 

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