A Guide to the Canine Immune System

The canine immune system is the command center for a dog's defensive troops. This system scans the molecules of foreign objects (antigens) in a dog's body and sets a course to eliminate them.

Innate and Adaptive Systems

Dogs have two divisions within their immune systems based on their function: the innate and adaptive systems.

The innate immune system is on the forefront of a dog's defenses. They are like the bouncers of a dog's body and work hard to keep foreign molecules out. This division of the immune system doesn't change its reaction to invaders after multiple exposures. Parts of a dog's body that are part of this innate immune system include mucous, skin, chemicals in saliva and stomach acids.

The adaptive immune system is like the special ops. division in a dog as they combat specific invaders. The adaptive system changes its tactical methods based on the type of substance that's invading a dog's body. The agents within this defensive system have communication with the each other, retain a memory of foreign substances, and change their combat methods based on those memories or changes the invaders have made.

The innate and adaptive immune systems work together. Hopefully a dog's invaders are stopped by the innate system, which is first in line, so a dog doesn't experience any illnesses. However, if an invader does get past the innate system, the adaptive system works as a backup team to help a dog recover from the illness that attacked him.

Dog Immune System Cells

A dog has special agents, cells, in his immune system that have special functions: monocytes, macrophages, granulocytes and lymphocytes.

Monocytes and macrophages are cells that begin a dog's bone marrow and travel into the body. Monocytes travel into a dog's blood stream and the macrophages go into the tissues. These cells kill and digest antigens and give information about the invaders to other cells.

Granulocytes come in many different forms and are part of the innate immune system. They, too, travel from a dog's bone marrow to the bloodstream and tissues, find an antigen, and kill and digest it. Granulocytes, however, don't share information about the invader with other cells.

Lymphocytes are the trained forces within the immune system. As they mature, they are trained on how to best protect the area of the body they'll be assigned to.

Canine Immunity Building

A dog can build his immunity in two different ways. First, a dog's immune system is built when he's exposed to an antigen because of an infection or a vaccination. When this happens, a dog's body creates immunity to an antigen on its own and creates antibodies throughout a dog's life, a process called active immunity.

When defenses are given to a dog, this is called passive immunity. Examples of this include bone marrow transplants or antibodies puppies receive from their mothers before they're born.

The canine immune system is complex and extremely organized. When this system isn't coordinated an autoimmune disease or negative reaction can result. It's important that a dog be in good physical condition so his immunity remains strong.