A sudden red, hot, swollen flare

What this tends to look like

• Came on within hours to a day or two
• Visibly red, warm, and swollen or puffy
• Sometimes raised welts or hives
• May follow a sting, a bite, a new plant, a new shampoo or a new cleaning product
• Often very itchy or tender to touch

What is usually going on

Rapid onset with heat and swelling is an acute inflammatory reaction rather than a chronic allergy, and the trigger is often identifiable and recent: an insect sting, a contact irritant, a new product. Acute flares frequently settle on their own once the trigger is gone. The thing to be alert to is spread, because a reaction that is still expanding is a reaction that could involve the airway.

What people commonly use

Educational information only — not veterinary advice. Check with your vet before starting anything new.

Where to find them

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What you can do at home

• Apply a cool compress for five to ten minutes at a time. Cool, not ice, and never directly on skin
• Work out what is new. Shampoo, bedding detergent, a plant, a lawn treatment, a room spray
• Rinse the area with plain lukewarm water if a contact irritant is plausible
• Stop the itch-scratch cycle physically. A recovery collar for a day beats a week of self-trauma
• Photograph it now. If it changes overnight you will want the comparison, and so will your vet

When to stop and call your vet

• Any swelling of the face, muzzle or eyes, or any change in breathing, means go now rather than monitor
• The area is still spreading after a few hours
• Your pet seems unwell in themselves, not just itchy
• It is not clearly improving within 24 to 48 hours