You may have a malpractice case against the vet, but unfortunately:1) There is no compensation in the courts for a dog's pain and suffering, so all you could recover would be the cost of unnecessary or harmful treatments.2) To prove that the treatments were unnecessary or harmful, you'd need the testimony of a veterinary expert witness--basically, another vet who examined or autopsied your dog, or at least reviewed the charts and file. That's because the fact that the treatments did not work does not  by itself prove malpractice--plenty of times, in human and animal medicine, the care provider does everything they are expected to and the patient does not recover. Such expert witnesses almost always are expensive--you have to pay for their time--and you can't get the witness cost back in the lawsuit. You are likely to spend as much or more on the case then you could recover.