Inflammation in Dogs
Dog inflammation is a complex biological response of the dog’s body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators to repair the body.
Just as people may suffer from bronchitis, colitis, arthritis, tonsillitis or a range of other inflammatory (or “itis”) conditions, so too can your dog. Inflammation is the body’s immune response against foreign substances, injuries or infection. It can also result from autoimmune diseases, in which the body triggers an inflammatory response when there aren’t any invaders to battle.
Dog inflammation occurs when plasma and white blood cells are drawn to a part of the body to fight infection, take away dead cells and initiate tissue repair. Increased blood flow to the area causes the region to appear reddened and feel warm. The blood vessels become more permeable, and leak fluid into the surrounding tissue, causing swelling. Chemicals are released into the tissue or blood to fight infection and do other jobs. But inflammation comes with a price: Increased pressure from swelling, along with the release of certain chemicals such as bradykinin and histamine, stimulate nerve endings and cause pain. Anytime you see inflammation, expect that your dog hurts.
In addition, chronic inflammation can predispose your dog to certain diseases, even some types of cancer. And more evidence is compiling that chronic inflammation is far more common than we once thought.
Inflammatory Conditions for Dogs
Sometimes inflammation is obvious. A dog with a recent cut or burn will have inflamed tissue in the injured area; a dog with an ear infection will often have an inflamed ear canal; a dog with periodontal disease will have inflamed gums; a dog with an allergic reaction to fleas will have inflamed skin. Sometimes the inflammation is internal and not so obvious; a dog with an inflamed prostate, pancreas or kidney may be in intense pain, but you can’t see the cause.
Inflammatory disease can be acute or chronic, mild or severe. Some examples:
Arthritis is an especially common condition accompanied by inflammation. The joint becomes filled with extra cells and inflammatory substances, causing irritation, wearing down of the cartilage, swelling of the joint lining, stiffness, and pain. Some, but not all, types of arthritis are thought to be caused by inflammation that has been misdirected. This is less the case in osteoarthritis, in which inflammation may occur in response to damage to the cartilage in the joint.
Asthma is a disease of inflammation caused by the actions of inflammatory cells such as mast cells, eosinophils, neutrophils, T- lymphocytes, epithelial cells, and macrophages. Inflammation of the airways produces the classic symptoms of asthma: coughing, wheezing, chest-tightening, and difficulty breathing.
Inflammatory bowel disease: Inflammation of the stomach or intestinal lining inhibits normal digestion of food and can cause chronic vomiting, long-term diarrhea, weight loss and abdominal pain that may come and go. The underlying cause may be genetic, food allergies, parasites, bacteria or other reasons not yet understood.
Inflammatory joint disease: usually caused by an infection, such as bacterial or fungal infection, tick-borne disease, and Rocky Mountain spotted fever. This type of arthritis can also be caused by an underlying defect in your dog’s immune system, which may be hereditary.
Conjunctivitis: Inflammation of the conjunctiva of the dog’s eye is usually caused by irritants, allergies or dry eye.
Dermatitis: Inflammation of the skin.
Encephalitis: Inflammation of the brain can cause a variety of neurological and behavioral signs, as well as pain. It may also be associated with inflammation of the spinal cord (myelitis) or brain covering (meningitis).
Glomerulonephritis: This inflammatory process in the kidneys can cause chronic kidney failure.
Pancreatitis: Inflammation of the pancreas causes intense pain, with the condition often recurring throughout the dog’s life. It’s most often seen in middle-age or older overweight dogs.
Masticatory muscle myositis: This inflammatory disease of the jaw muscles starts with swelling and pain, and with time leads to atrophy of the jaw muscles.
Panosteitis: This painful inflammation of the long bones is seen in young dogs, usually between 5 and 19 months of age. It affects the front legs more often, and the dog may find it too painful to play. The condition can last from days to months and can be mild or severe.
Uveitis: Inflammation of the eye’s iris and muscles that control the lens can be very painful; it is most often immune-mediated but can be caused by a variety of factors.
Any condition that ends in “itis” refers to inflammation: folliculitis, glomerulonephritis, hepatitis, lymphadenitis, meningitis, and myocarditis are all issues found in dogs directly related to inflammation.
Those aren’t the only kinds of inflammation your dog may have. In truth, many, if not most, types of inflammation tend to fly under the radar and aren’t named as a particular disease condition.
Exercise & Canine Inflammation
Exercising causes inflammation of the muscles. In fact, exercise is an interesting case as regards inflammation. Regular exercise tends to lower markers of systemic inflammation. Acute exercise tends to increase markers of acute inflammation. Repeatedly performing rigorous exercise before inflammation subsides from previous exercise can create a condition of chronic inflammation. The take-home message is to work up to higher levels of exercise gradually, and provide rest times and proper nutrition between periods of intense exercise. That’s essentially what we’ve been told for years to avoid chronic pain; now we know that’s probably because it also avoids chronic inflammation.
The Downside of Inflammation for Dogs
While inflammation is a helpful process combating injuries and invaders, chronic inflammation can also be harmful as it can cause chronic pain and even increase the chances of some diseases.