It sounds like there may be a secondary infection to the usual tenderness. Maybe adjusting the aspirin dose for Lucy's specific weight will help with pain. Hydrogen peroxide washes on her paw (be very careful she doesn't ingest any) may help until you get her to the vet (Monday?). From what you describe, it's probably a bacterial infection, but he needs to determine this for sure and provide the proper treatment.
I think you're doing all the right things. Keeping her off her feet or providing only 'softer' surfaces until this is resolved is all you can do along with the aspirin. I'd also suggest cold compresses, but she may not care to cooperate with that.
The aspirin calculations for dogs: 25-35 mg per kg of weight has been found to achieve the ideal concentration, but only administered once every 8 hours.
For a 10 lb dog (4.5 kg) 1 ½ to 2 of those low dose, 80-81 mg ‘heart’ or ‘baby’ aspirins would do. For a 30 lb dog (13.6 kg) a single regular aspirin should work. It’s very important to do the math and be sure the right dose is given for the body weight.
Dogs exceeding 100-300 mg of aspirin (per kg of weight) per day developed gastric ulcers and other complications within weeks. Even at just 50 mg per kg of weight (every 12 hours) there was vomiting as a common side effect within a couple of hours of administration.
( 1 kg = 2.2 lbs)
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