Can Allergies Affect Your Pet's Normally Healthy Immune System?
Many people suffer from allergies, whether they are from pollen, dust mites, pet dander, or mold. But did you know that pets can have allergies too? Pet's allergies can be a little harder to detect because animals don't sneeze in response to them. Due to this, pets can have their allergies go untreated for long periods of time. This can be dangerous to their immune system due to the polarized nature of a common immune tactic: cell-mediated immunity.
Pet's Allergies and Allergy Symptoms
Pets can be allergic to many of the same things humans are allergic to, including household dust, dust mites, pollen, mold spores, pet dander, grass, and fleas. But instead of having itchy/watery eyes and sneezing, dogs usually scratch incessantly during an allergic reaction. Small oozing skin eruptions or rashes may appear. Pets can also get ear infections from allergies. As a result, pets will often clean themselves obsessively and chew, scratch, or rub their itchy skin.
What Causes An Allergy?
Why some pets have allergies while others don't is still poorly understood, but is very likely related to the animal's genetics. The actual mechanism of the allergy, however, is quite well-understood, involving an over-reaction of the immune system. A specific kind of antibody (protein particle) is responsible for causing an immune reaction: IgE. Antibodies of this type (there are four others) bind to cells called eosinophils. When the IgE binds to both an eosinophil and another object (like a mold spore), the eosinophil releases granules small particles which cause potent inflammation.
T Helper Cells
However, antibodies aren't simply made out of thin air. They are produced by a certain kind of immune cell called a B cell. B cells are instructed by T2 Helper cells (TH2) as to what kind and how much antibody to produce. There is also another kind of T Helper cell, called a T1 Helper cell (TH1), which is responsible for instructing macrophages (cells which eat harmful particles).
The interesting thing about TH1 and TH2 cells is that they compete with each other. The activation of a TH2 response causes the down-regulation of a TH1 response. This is presumably to force the immune system to focus its energy on one type of response, rather than splitting that energy between the two and thereby weakening both responses. While this is usually helpful during an infection (TH1 responses are better at ridding the body of viruses while TH2 responses are better at battling bacteria), it can be problematic when unnecessary immune actions (like allergies) are present. Allergies cause a TH2-biased (antibody-based) response, resulting in a down-regulation of the TH1 response. Pets with uncontrolled allergies can therefore be more susceptible to viral infections since that form of response is constantly suppressed.
Controlling Your Pet's Allergies
To limit a TH2-biased response, the source of the allergy must be removed from the pet's environment in order to prevent uncontrolled allergy symptoms. Reducing the occurrence of allergic reactions will allow the TH1 response to remain uninhibited. It is also important to give your pet proper nutrition and exercise to keep the immune system working optimally.
Photo Credit: AceNZ