My son's friends German Sheperad has it what is it and how can they help him. he is crossing his hind legs all the time.

It is an abnormal bend/curve in the spine which can put pressure on the spinal cord and the nerves which go to other parts of the body causing weakness or paralysis.

He is 9 it started 2 weeks ago and getting worse what is the best treatment

What has the vet said as wonder if they can refer to a dog osteopath as should imagine that may help.

Is it spondylitis or spondylosis? These terms seems to be interchangeable and it is confusing. Either way, inflammation of the spine results and there is a type where some parts of the spine fuse together limiting movement, and growth of additional bony spurs. This is what my first GSD developed, even though it was referred to initially as spondylosis.

Any inflammation is treated with anti inflammatory drugs, usually NSAIDs, although initially something like prednisolone is often used to take down inflammation quickly, but only short term, and then moved on to NSAIDs. Plus painkillers as required, as it is a painful condition. There is not a cure, only management.  What have the vets suggested?

My girl did benefit from osteopathy, but it has to be done very carefully especially if there are addtiional bone spurs that have grown.

TBH though, crossing of the hind legs all the time doesn't sound like a symptom of spondylitis, it sounds more like Degenerative Myelopathy, though this usually comes on more slowly.