Right Hind Leg Giving Out on Dalmation

My 12 year old Dalmation is having a problem with her right hind leg: while she's walking, it kicks out behind her. Also, when she lies down it will kick out as well. This has never happened before and I'm scared.
Any thoughts would be appreciated.
Thank you

If you have any concerns regarding health issues such as the one you are describing you really need to see your vet - we have researched a little about this and one vet on a well known site referred to a similar problem as (partial loss of feeling and function) in the hindlimb. Which can be caused by spinal problems such as a disk (an intervertebral disk) which is slipping and pressing on the spinal cord on one side (the right side for example) but has not completely slipped out all the way.

This is not our advice as we are not trained vets - please take your pooch to the vet for professional advice.