Dog Immune System Basics

The dog immune system is a complex and effective defence against the bacteria and viruses that your dog meets in everyday life. The system is always changing and developing, building up resistance to new bacteria it encounters. However, your dog's immune system can also cause problems, as detailed below.

What Does Your Dog's Immune System Do?

The canine immune system defends its body from bacteria and viruses. It recognizes organisms which don't belong in the dog's body from their molecular structure, and works to expel them from the body or destroy them. These things are organisms like bacteria and viruses and also bodies like pollen, which can be expelled with a mechanism like sneezing.

How the Immune System Works

There are two parts to your dog's immune system.

The innate immune system is built in. It is your dog's first defence against foreign objects which are potentially harmful and is designed to keep things out. The innate immune system includes things like:

  • Skin
  • Stomach acid
  • Mucous in the respiratory system
  • Certain cells (phagocytes and monocytes) that eat any foreign bodies in your dog's system
  • Certain chemicals in the saliva

The adaptive immune system keeps developing as your dog grows. This part of the immune system defends your dog against specific diseases, viruses or bacteria and develops its own method for each different type of foreign body. The adaptive immune system can develop a ‘memory' of each different foreign body it encounters. This means the next time it comes into contact with the same bacteria or virus, it already knows how to fight it off and can do so faster.

The two parts of the immune system work together: if a foreign body gets past the innate immune system, the adaptive immune system is there to help defend your dog.

Building Up The Immune System

There are two ways your dog's immune system strengthens itself: actively and passively.

Active immunity occurs when your dog encounters an unknown foreign body. Whether this occurs naturally or because of a vaccination, your dog's body will produce the cells necessary to kill the foreign object. Once these cells have been produced, the next time your dog is exposed to that particular foreign body, they will be able to work faster.

Passive immunity refers to the cells and antibodies that are passed on from your dog's mother in the womb. The disadvantage to this kind of immunity is that once the antibodies break down with age, your dog's body cannot replenish them until he comes into contact with them again.

Potential Problems With Your Dog's Immune System

Your dog is completely reliant on its immune system to survive. If both the innate and adaptive parts fail, then death will occur. There are several conditions which can affect your dog and alter the way its immune system behaves.

  • Autoimmunity is when your dog's immune system starts viewing parts of your dog's body as foreign and begins attacking them.
  • Hypersensitivity occurs when your dog's immune system reacts too strongly to a stimulus. The body then produces too many antibodies or other cells that help with immunity, and can cause an adverse reaction in your dog.
  • Immunosuppression and immunodeficiency is caused by certain conditions which prevent the immune system from working properly. This kind of problem can also be caused by genetics or a lack of key nutrients in your dog's diet.
  • The immune system is necessary for keeping your dog alive. It is important to nurture it and keep it healthy. A good diet, healthy lifestyle and exercise will usually be enough to do this, but if you have any concerns about your pet's immune system it is always a good idea to ask your vet for advice.