No matter how slight the limp, your dog is limping because walking normally and applying full force to the limb hurts.
Dogs can limp for many reasons. Active or heavy pets can twist and strain things just like humans do. Any dog can jump or run and twist or turn a joint in a manner that causes temporary discomfort. Most injuries caused by such things are short-lived. They arrive suddenly and disappear within a day if not a few hours. In most cases, simply restricting activity will solve the problem.
If limping/lameness continues for more than a day or so, had a gradual onset or is severe enough that the pet is extremely uncomfortable, then it’s time to see your veterinarian.
Limping can be a sign of:
Abscess or puncture in the foot
Abscess or puncture higher on the leg
A broken bone
A torn ligament
Structural damage or deformity
Muscles strain or injury
An unseen bruise or cut
Growth pains in pups
Certain cases of limping are considered an emergency: Possible fracture, hit by car, attacked by larger/bigger animal, bleeding, any signs of collapse, or possible snake bite.’