Dogs can get over the counter anti-histamines and something containing Cetirizine or Chlorphenamine are usually the most effective.
The swelling in a sting is due to the toxin in the sting and the action of histamine, an anti-inflammatory may not really do anything.
Be VERY CAREFUL giving a dogs anti-inflammatory drugs! Anti-inflammatory drugs damage the lining of the stomach and can cause ulcers. If anti-inflammatory drugs are given over a period of time, a PPI (proton pump inhibitor) is usually also given to protect the gun lining.
Huge problems arise if a dog is stung on the tongue or in the oesophagus.
The number 1 priority is to keep that airway open if the sting site and surrounding tissue swells and compromises the dog' airway or ability to breathe effectively. First aid is is to reduce swelling as much and as fast as possible; copious amounts of cold water (or get Mutley to eat ice cubes) to reduce swelling and maintain an airway...An anti-histamine can take some time to act effectively and reduce swelling.