Your dog is having an acute (sudden) allergic reaction. Insect bites are common causes of this type of allergic reaction. Have your dog examined by a veterinarian, they can give your dog injectable medication that will work rapidly and make him feel better. If your dog starts vomiting, becomes severely lethargic, or has difficulty breathing this is an emergency--seek veterinary attention immediately.
If you are unable to seek veterinary attention--start Benadryl at home. The dose is 1 milligram per pound of body weight given every 8 hours. Do not use the Cold and Sinus variety; the Children's liquid is best for small dogs. Talk to your veterinarian further for exact dosing.
If you are unable to seek veterinary attention--start Benadryl at home. The dose is 1 milligram per pound of body weight given every 8 hours. Do not use the Cold and Sinus variety; the Children's liquid is best for small dogs. Talk to your veterinarian further for exact dosing.