When you decide to buy or adopt a dog, especially an adult dog, you need to learn as much about that dog's personal history as you possibly can. Learning about previous problems or ongoing issues with the dog before you bring him home will help you plan ahead.
Previous Owner or Rescue Group
The source you get your new dog from may determine how much information you can get about your dog. You should be able to get plenty of information about your dog's history if you are buying him from a reputable previous owner. A dog who is coming from a shelter may not have much information available. In the case of a shelter dog, the organization will be able to disclose only whatever information they have accumulated while the dog has been in their care or that the previous owner told them.
You need to ask the dog's previous owner for his veterinary records as well as for information about any health problems the dog has. Make sure the dog is current on all vaccinations, worming and heartworm preventative. If the dog has medical problems, talk to the veterinarian before you bring the dog home. You do not want to purchase a new dog only to discover you cannot afford his medications or deal with his health problems.
Behavior and Training
VetStreet recommends asking the person selling you the dog for as much information about the animal's history as they can possibly give you. Ask the previous owner if the dog has any behavior or training concerns you will need to address. Ask why the dog is being rehomed. Find out if the dog has ever bitten anyone or behaved in an aggressive manner toward people or other pets. Ask what type of obedience training the dog has completed, if any.