Although most allergy sufferers will only ever experience mild albeit irritating symptoms, a minority may have an allergy response whose characteristics are considered to be more severe medically and capable of causing greater distress for the patient. In particular, they fall into 2 groups:
| Term | Location | Symptoms |
| Urticaria (a.k.a. hives, welts, wheals) |
On skin (upper dermis) |
Elevated pale red bumps/lesions/plaques/rash that may be accompanied by a burning, stinging or pain sensation in affected areas. |
| Angioedema | Under skin (dermis, subcutaneous tissue) |
Swelling that can be accompanied by pain, itching, numbness or tingling sensation in affected areas. Typically affects the face and eyes, mouth, tongue and throat but it may include other areas as well e.g. feet/pads or abdomen. |
Variability of symptoms means that an individual may not develop both conditions in an allergic response or that the severity of one form may be more significant. However, they are often present together in the most severe form of allergic reaction known as anaphylaxis.
Anaphylaxis
Anaphylaxis, the general term used to describe an extreme and potentially life-threatening allergic response, is thought to be relatively rare in both dogs and people (affects less than 3% of human population – Kemp 2007).
It usually involves a number of body systems being severely impacted which can include cardiac function, central nervous system, gastrointestinal and urinary system, respiratory system and the skin. For example, urticaria (hives), itchiness or rashes may be accompanied by gastrointestinal e.g. cramps, or central nervous system symptoms e.g. confusion or headaches. However, it is changes in cardiac function e.g. sudden drop in blood pressure or arrhythmia, and serious respiratory symptoms associated with swelling of the airways (angioedema) that makes anaphylaxis a life-threatening condition.
Symptoms typically develop within minutes e.g. insect stings or intravenous medications, to within a few hours of exposure to the allergen e.g. food ingredient. In the case of anaphylaxis, it is essential to seek immediate assistance from a veterinarian, even if the owner has administered an epinephrine autoinjector (e.g. EpiPen) to a dog that has previously been diagnosed ‘at risk’.
Epinephrine, also known as adrenaline, is a hormone and neurotransmitter molecule that counters the key symptoms of anaphylaxis by reducing angioedema and facilitating opening of the airways, whilst constricting the blood vessels which helps to elevate blood pressure. However, without expert medical appraisal and possible further treatment, self-administered epinephrine may only provide a temporary respite before further complications develop that can sometimes prove fatal.
