Hives is an allergic skin reaction causing localized redness, swelling, and itching.
Hives is a reaction of the body’s immune system that causes areas of the skin to swell, itch, and become reddened.
dog with hives
Hives is an allergic reaction. The body’s immune system is normally responsible for protection from foreign invaders. When it becomes sensitised to normally harmless substances, the resulting reaction is called an allergy. An attack of hives is set off when such a substance, called an allergen, is ingested, inhaled, or otherwise contacted. It interacts with immune cells called mast cells, which reside in the skin, airways, and digestive system. When mast cells encounter an allergen, they release histamine and other chemicals, both locally and into the bloodstream. These chemicals cause blood vessels to become more porous, allowing fluid to accumulate in tissue and leading to the swollen and reddish appearance of hives. Some of the chemicals released sensitise pain nerve endings, causing the affected area to become itchy and sensitive.
signs and symptoms:
Redness, swelling, and itching of small areas of the skin. These patches usually grow and recede in less than a day, but may be replaced by hives in other locations. Angioedema is characterized by more diffuse swelling. Swelling of the airways may cause wheezing and respiratory distress. In severe cases, airway obstruction may occur.