It is not uncommon for dogs to become lame at some time in their life. In young athletic dogs sudden (acute) lameness may be the result of a soft tissue injury such as a sprain or muscle injury. Lameness that doesn't resolve within a few days of rest should be investigated by your veterinary surgeon. Causes of chronic lameness include more severe damage to ligaments (such as torn knee ligaments) or mechanical causes of lameness such as luxating patellae (loose knee caps). Lameness can also be caused by neurological problems such as a slipped disc. Dogs will sometimes lick continually at a painful joint and in dogs with pale coloured coats the saliva may start to stain the fur over the affected joint. Occasionally the joint may appear hot or swollen but more usually you will not be able to recognise any change in the joint. The signs in some animals can be very obvious whereas other pets may just become quieter or more grumpy if they are in discomfort.
Physical changes in joints may lead to development of arthritis in later life. Arthritis causes pain and stiffness in the joints. If your pet has arthritis you may notice they are not as keen to exercise as in the past and they may limp or seem to be stiff (particularly when getting up from rest). This stiffness may get better after being out for a walk, and sometimes cold and/or damp weather may appear to make signs worse.
Some breeds of dogs have specific breed-related problems such as elbow dysplasia in Labradors and hip dysplasia in German shepherd dogs. In these breeds your vet can perform screening X-rays to see if your pet is affected. If you are planning to breed from your pet and it belongs to a breed with any specific health problems you should contact your vet for advice to see if any testing is necessary before breeding.