You may get a technical answer here. If not, go to K9Cushings website and there are very knowledgeable, technical people there who can probably answer your question.

thanks, i'll try that bichon

Luvdogs (and don't we all!!). You're welcome. Those folks are a Godsend to me on an ongoing basis. :)

Arthritis is another term for degenerative joint disease. It usually shows up as a proliferative bone lesion no matter which joint you are talking about. Lots of times you can see bone spurs, osteophytes, and rough edges to the bone. Depending on the view taken of the radiograph, if the proliferative lesion was superimposed on another bone or upon itself, it would show up as denser/brighter. But usually the lesions are pretty obvious- ie not overlapping- on the opposite view. Healthy bone has a variety of densities depending on the bone, view, and specific location of the bone you are looking at.

That said, there is no reason that a dog can't have both arthritis of the spine AND a torn ACL. A torn ACL won't show up on spinal radiographs though. Usually I can diagnose an ACL just on PE, sometimes requiring sedation to manipulate the knee. I do radiographs to evaluate for surgery type but the diagnosis of torn ACL is made on the PE.

Also it should be noted that spinal arthritis (aka spondylosis) does not necessarily correlate with any symptoms. In fact, more often than not, it doesn't. Most dogs with severe spondylosis are completely pain free (as far as we can tell) though they are likely stiffer and less flexible and may have a limited range of motion and decreased ability to jump or run. So diagnosing a lameness based on spondylosis is indeed a bit suspect. You certainly can get lameness due to back problems, but usually those problems are either due to nerve entrapment, disc disease or other things that are not always visible on a normal radiograph. Your dog should be looked at a bit more closely, and if it turns out it does have an ACL, that is likely the cause of lameness (though, as mentioned, there can be multiple causes... just less likely).

I guess I should be a bit more accurate saying that what is often called 'spinal arthritis' is actually spondylosis, but it's really not even arthritis (since it does not occur at real joints). You can get true spinal arthritis of the joints in the back, but that disease cannot cause lameness in a leg... just back pain and stiffness.

Actually the spine is nothing but a series of joints so it is very possible to get arthritis of the spine, although what we see on radiographs is usually called spondylosis. Spondylosis is an overgrowing of the vertebrae, in the body's attempt to stabilize an unstable joint. However spondylosis can lead to spinal compression causing neurological lameness.

It happened to my own dog, K'Ehleyr, and resulted in her becoming paralyzed in both rear legs which directly led to me euthanizing her. She had multiple problem disks according to her MRI, and the surgeons did not know which disk or disks were causing her lameness, therefore couldn't operate on the right one(s). I was able to control her pain for 1.5 years before she went lame but I was not going to put her through a major surgery with little chance of actually getting better.

just weighing in a tad here... it's important to know that at different stages of both of these conditions, both are also involved in referred pain (pain felt not at the sight of origin) as both have many components involved.

Well, since this person did ask a technical question, techincally the part of the spine involving the disk and vertibrae are not joints, though the articular facets that attatch each disc to each other dorsal to the vertebra-disc-vertebra connections are true joints and 'true' arthritis can develop there, often with typical symptoms involved with arthitis (pain and stiffness). However, arthritis at these joints is not referred to as spondylosis, but spinal arthritis. True spondylisis is not arthritis, however, as it does not invovle a true joint. Just technically speaking.