What should you know about dog hives causes?

Hives are a reaction of immune cells in the skin. A food, medicine, vaccine, insect sting, plant, shampoo, or cleaning product may be involved, but sometimes no single trigger is found. Heat, cold, pressure, exercise, or an infection can also bring on welts. Hives present with raised, itchy areas; they do not by themselves identify the cause. Compare the pattern with [Hives](/conditions/urticaria/), [Itchy Skin](/symptoms/itchy-skin/), and [Skin Swelling](/symptoms/skin-swelling/).

Note when the welts began, what touched the skin, recent foods or medicines, activity, temperature, and whether each patch fades or moves. Stop a suspected non-essential product, but do not stop a prescribed medicine without advice. Photograph the rash while it is visible. A clinician may use the history and examination to decide whether [Antihistamine Treatment](/treatments/medical-dermatology/oral-antihistamine-therapy/) is suitable; testing is guided by the suspected trigger rather than performed automatically.

Seek emergency help for breathing difficulty, throat tightness, tongue swelling, dizziness, collapse, or rapidly spreading symptoms. Deep swelling of the lips or face may be [Angioedema](/conditions/angioedema/). Arrange medical review when episodes recur, last longer than expected, follow a new medicine, or leave bruising or pain rather than fading.

Which exposures fit the timing of this episode? Could a medicine, sting, infection, or physical trigger be responsible? What should be recorded before the next episode, and what emergency plan is appropriate?