Ask the vet - Dog
Why is my dog stiff and sometimes a bit unsteady when it gets up?
Vet at FirstVet answers:
Usually dogs are stiff when they get up due to pain, often in joints or musculature in the back or limbs. Unsteadiness can be seen in association with pain when trying to avoid putting weight on the painful limb. However, if unsteadiness comes suddenly it is important to contact a vet as soon as possible as it may be due to a neurological problem, for example, a herniated (slipped) vertebral disc. If your dog has gradually become more stiff and unsteady over a longer period of time it is still a good idea to consult a vet. Short walks on the lead, with no jumping (including on and off the couch) or playing is recommended until your dog has seen a vet. Make sure to help it in and out of the car, and up and down stairs to avoid any further damage.