Dogs afflicted with CHD may exhibit many symptoms, lameness, unwillingness to walk upstairs, difficulty rising from a sit or a dropped (sleeping) position. They may also exhibit personality changes due to pain. The only certain diagnosis is by X-ray. Some vets may be able to see, from the X-rays, that the animal is suffering from the condition but normally it is advisable to have the X-ray reviewed by a professional using a recognised scoring system.
It is not possible to predict when clinical signs will develop; environmental factors such as the amount of exercise and the weather etc can make its mark on the severity of the symptoms observed. There also is no correlation between the severity of changes found by X-ray and the clinical findings for example dogs with severe arthritis can jump, play and run as if there was nothing evident and yet some dogs have barely any arthritic X-ray changes yet they are severely lame and clearly in pain.