Spondylosis deformans (ankylosing spondylitis, ossifying spondylitis) is the formation of osteophytes (bone spurs) around the margins of vertebral endplates. The formation of osteophytes is the non-inflammatory bony response to degenerative changes in the intervertebral discs. Obviously, older canine patients are more likely to be affected, with large breeds considered to have a higher incidence.

It has often been argued that spondylosis deformans is not of clinical importance. I disagree. I have found varying levels of pain and proprioception deficits in the hind legs --- with associated weakness in the majority of affected individuals, not the minority. Our inability to properly define the effects of pain in many animals has allowed the propagation of this misinformation.

I contend that the osteophytes place pressure on spinal nerve roots, resulting in varying degrees of inflammation that lead to varied symptoms. These symptoms include, but are not limited to, pain, weakness and delayed proprioceptive reflexes in the hind limbs. All these symptoms may appear I a single patient or as individual signs.

In the past treatment for the obvious effects of inflammation due to osteophyte pressure on spinal nerve roots has been limited to non-steroidal, anti-inflammatory drugs or corticosteroids. Both of these treatment modalities carry a certain risk of undesirable side effects. For this reason, when I met with Jeff Brown of Eudaemonic Corp. in August 1992 to discuss the effects of treating intervertebral disc disease with Rubeola Virus Immunomodulator (RVI) I was much more interested in using it for spondylitic lesions than for IVD. RVI is approved for use in equine for treatment of chronic myositis and myofascial inflammation; it stimulates T-lymphocytes to help eliminate inflammation.

A set protocol was determined for selection and treatment of spondylosis deformans cases:

1. The dogs selected must have been radiographically diagnosed with spondylosis deformans.
2. Coxofemoral radiographs must have been included since many of our patients have osteoarthritis of the coxofemoral joints.
3. The dogs must have shown proprioceptive deficits in either one or both rear legs.

Pain was not set as a criterion due to the difficulty in truly assessing it, not to mention the fact that most of our patients have osteoarthritic changes in addition to spondylosis.

Our first patient was a diagnosed systemic lupus erythematosus case: a 7-year-old spayed female Great Dane with osteoarthritis of both coxofemoral joints and her left stifle. Radiographs had been taken, and treatment began with Adequan for the osteoarthritis. This regimen of therapy was highly effective, but she still had severe proprioceptive deficits and weakness in her hind legs. Therefore, she was chosen first.

A trial dosage of 2cc of RVI given subcutaneously was administered daily for six days. Improvement in her hind limbs was evident after four injections. After six injections, absolutely no proprioceptive deficits were found. The owner was overwhelmed at the response.

The patient was checked every week for proprioceptive deficits, and she remained normal until 32 days post-treatment. At that time 2cc boosters were given daily for four days, with return to normal after three days. Unfortunately, 19 days after this series, the reflexes diminished again.

The dosage was arbitrarily increased to a single 3cc booster dose given subcutaneously. Improvement occurred within 24 hours. There have not been proprioceptive deficits in the hind legs for more than eight months now. However, 3cc boosters have been administered every 90 days.

Since the first success, nine other patients have been treated with varying degrees of spondylosis and osteoarthritis. All have received Adequan when osteoarthritis was diagnosed. The results have been astonishing.

Seven out of 10 patients have had excellent response with no proprioceptive deficits ranging from 30 to 90 days post injections. Two patients have had good results with a drastic improvement in proprioceptive deficits but not a complete return to normal. One patient had only fair results with some improvement, but this patient died of a pre-existing renal failure condition within two weeks of treatment.

Included in the treatment group were one Great Dane, one Old English Sheepdog, one Collie, one Shetland Sheepdog, two Dalmatians, two Labrador Retrievers and two mixed-breed dogs. With the exception of the Shetland Sheepdogs, all dogs are over 27kg. It was found that 3cc of RVI caused faster and longer lasting improvement in dogs over 30 kg. Therefore, on all subsequent cases of 30kg or greater, 3cc of RVI is given subcutaneously daily for six days.

It was also determined that, although two dogs showed improvement after two injections, seven out of ten did not show improvement until at least four injections. Therefore, six injections are probably necessary to definitely rule out a lack of improvement. The only observed side effect has been a localized swelling similar to other vaccine-induced localized reactions. This reaction has only occurred in three out of 10 patients.

I am extremely optimistic about this drug since it may offer an alternative to treating ossifying spondylitis with steroid or on-steroidal anti-inflammatory medications without the side effects. I hope further study and investigation of RVI will be instituted at the university level.

Dr Polley (Missouri 1971) owns Harvester Animal Clinic, St. Charles, MO. He lectures on many topics and is a member of this magazine’s Advisory Board. 314-447-3565.

Comments: Delayed proprioceptive reflexes after 29 days from initial series; gave 3cc booster, no delayed reflexes within 7 days; gave second 3cc booster 17 days after first; improvement for 34 days.