Tips to Strengthen Your Dog's Immune System

A dog's immune system can be weakened by various causes. Learn about them here and find out what actions to take to strengthen it!
Tips to Strengthen Your Dog's Immune System
Sebastian Ramirez Ocampo

Written and verified by the veterinarian and zootechnician Sebastian Ramirez Ocampo.

Last update: 29 August, 2023

Through different mechanisms, your dog’s immune system is responsible for identifying and eliminating potential threats to health and the natural balance of its body. It’s composed of various organs, cells, and molecules that act together against infectious agents, harmful substances, and even elements that function incorrectly.

If you want your pet to enjoy a long and healthy life, strengthening its immune system is essential. To achieve this, discover in this article the best strategies and what you should avoid so that it doesn’t weaken. Keep reading!

How does your dog’s immune system work?

The main function of your dog’s immune system is the defense of the body against the attack and invasion of foreign agents or its cells that act abnormally. This process is known as immune response, and it’s stimulated by the action of different molecular structures called antigens. Among the main ones, the following can be distinguished:

  • viruses
  • bacteria
  • fungi
  • parasites
  • cancer cells
  • chemicals
  • allergens

According to a document of the MSD Veterinary Manual, the immune system of dogs is composed of 3 lines of defense, which have a specific mechanism of action and are coordinated to generate an appropriate response to each situation.

Physical barriers

This is the first defense component of your dog’s immune system. Among the parts of the body that act as physical barriers, the following are the most important:

  • skin
  • cornea of the eye
  • mucous membranes (lining the respiratory, digestive, urinary, and reproductive tracts)

In addition, certain positive microorganisms help out, such as lacrimal bacteria or the microbes that make up the intestinal flora.

When the antigens manage to cross the physical barriers, the following lines of defense come into play.

Innate immunity

This is a response that’s present from birth and is characterized by being non-specific. This means that it acts in the same way against any foreign agent. Its mechanism of action is rapid, and several defense cells are involved:

  • neutrophils
  • macrophages
  • eosinophils
  • natural killer (NK)

Acute inflammation is the most important phenomenon involving innate immunity. During this process, white blood cells travel – rapidly – from the blood to the tissues to eliminate invading organisms and destroy injured cells.

3. Acquired immunity

Also known as adaptive immunity, it’s acquired as the body encounters different foreign agents. In practical terms, after an initial exposure, the immune system learns the best way to attack an antigen and develops memory to defend itself in the future.

Unlike the previous one, the response is more specific because it acts according to the element causing the damage or disease. This process involves, above all, the following:

  • T and B lymphocytes
  • antigen-presenting cells
  • cytokines

According to an article in the journal Veterinary Sciences, vaccines are used to stimulate the development of this immunity. For example, those designed against canine distemper or parvovirus present the immune system with a virus that is attenuated or incapable of producing disease. Thanks to this, the body identifies them and learns how to fight them in the future.

A dog receiving a vaccine.
Without an adequate vaccination schedule, the immune system won’t be able to defend itself against viral antigens. Credit: Unsplash.

Why does your dog’s immune system weaken and what are the consequences?

A weak immune system will result in your pet not having the ability to adequately defend itself against an antigen attack. In addition, your pet will be more prone to infections, will have a low resistance to infections, and will show a general weakening.

Therefore, their well-being will be compromised and their visits to the veterinarian will be more recurrent. Although the immune system of dogs is weakened by the very action of pathogens – when they manage to enter the organism – certain factors influence the body’s defenses to remain at a low level.

An investigation of the journal The Veterinary Clinics of North America states that among the main causes of non-infectious immunosuppression in dogs are the following.

Poor nutrition

Nutritional deficiencies are one of the main causes of a weak immune system. A lack of certain elements can lead to decreased white blood cell levels and antibody titers, as well as poor white blood cell response to various antigens.

For example, a diet lacking in protein leads to immunosuppression and low resistance to infection. This is because amino acids are involved in the activation of T and B lymphocytes, natural killer cells, and macrophages.

Similarly, deficiencies of minerals such as zinc and iron are associated with certain conditions:

  • Increased susceptibility to disease
  • Decreased antibody production
  • Low levels of lymphocytes

In addition, a lack of vitamins such as A, E and B complex lead to a weak and deficient immune system.


Certain drugs have immunosuppressive properties. In fact, they can affect the activation and proliferation of defense cells such as lymphocytes and macrophages. Some of these include the following:

  • glucocorticoids (dexamethasone and prednisolone)
  • azathioprine
  • cyclosporine
  • methotrexate


A surgical intervention can be a great burden on the immune system. In addition to this, anesthetic drugs, stress -associated with surgery- and pain can lead to a decrease in the body’s defenses.


As stated in a publication in the journal Animals, in situations of acute stress, the organism produces an immunopotentiating and pro-inflammatory response. However, when the stimulus persists and the stress becomes chronic, the opposite is triggered. That is, an immunosuppression with certain changes:

  • decrease in white blood cells
  • susceptibility to infections
  • reduced immune response

One of the causes may be prolonged hospitalizations, degenerative diseases, or lack of physical activity.


Weakening of the immune system in dogs can be caused by a number of substances. These include the following:

  • insecticides
  • herbicides
  • fungicides
  • heavy metals

In addition, fungi produce mycotoxins, which can contaminate animal food. This can have detrimental effects on the immune response. Therefore, it’s important to store concentrated food in a place free of moisture.

Tips for caring for and strengthening your dog’s immune system

As you can see, there are many factors that determine the optimal condition of your dog’s immune system. Below, you’ll find the best strategies to strengthen it and thus avoid the invasion of unwanted pathogens in your pet.

Adequate nutrition

According to a publication in the journal Clinical and Experimental Immunology, the gastrointestinal system plays a central role in the balance of animal immunity. In fact, as stated by the authors, 70% of the immune cells are housed in the digestive tissue.

For this reason, providing high-quality foods containing good sources of protein, vitamins, and minerals is the least that can be done to support a healthy immune system.

Similarly, high levels of antioxidants such as vitamins C and  E and carotenoids can prevent free radical damage. This is important because these molecules affect immune cells by oxidation processes and thus weaken the immune system. This is stated in an article in the journal Topics in Companion Animal Medicine.

Furthermore, this document states that the inclusion of prebiotics in the diet – especially after antibiotic therapy in stressful situations or in old age – helps the intestinal flora to recover and remain in good condition. Prebiotics used in veterinary medicine include the following:

  • Galactooligosaccharides: Found in vegetables, legumes, cereals, and honey.
  • Fructooligosaccharides: Found in fruits such as bananas, apples, carrots, blackberries, and pears.
  • Beta-glucans: Found in cereals such as oats and barley.

In addition to this, there are commercial products composed of these prebiotics to be included in the diet directly.

A dog eating wet dog food.
Providing a balanced diet is the first step for a dog to enjoy a strong immune system. Credit: Depositphotos.

Managing stress

As mentioned above, stressful situations can negatively influence your dog’s immune system. For this reason, the following actions are required for immunity to function properly:

  • physical activity
  • devoting time to training
  • stimulating their physical and cognitive abilities through play


According to an article in the journal University Medicine, there are drugs with immunomodulatory properties that stimulate the defense mechanisms of animals against the attack of viral, parasitic, bacterial, and fungal diseases:

  • Freund’s complete adjuvant (FCA)
  • lipopolysaccharides (LPS)
  • Omega interferon


Vaccination is one of the main strategies to stimulate and develop the immune system in dogs. Thanks to this, your dog’s body will be prepared for the attack of antigens of diverse origins.

Monitor the state of your dog’s defenses

Now that you know how your pet’s immunity works and what to do to strengthen it, it’s your duty as a guardian to watch over its well-being and avoid the appearance of diseases. Remember to always go to a professional and perform periodic check-ups to evaluate the state of his defenses.

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The contents of My Animals are written for informational purposes. They can't replace the diagnosis, advice, or treatment from a professional. In the case of any doubt, it's best to consult a trusted specialist.