I just checked your other thread and it referred me here so I decided to post here rather than add to the other long thread. Sort of giving that thread a rest! I was so worried when you didn't check back in, and I'm sorry to hear about all of your computer problems.

Bella's limp was intermittent as well so I still wouldn't rule out Lyme disease. In fact that is why the vet suggested Lyme first even before he tested her because the limp can come and go. Apparently that is sort of a "red flag." Regarding aggressiveness due to Lyme's, here is a quote from a page on Lyme disease. Note the sentence I put in bold. Fortunately that didn't happen with Bella since she was diagnosed and treated immediately. I think that is a symptom for a dog who has had the disease and it has gone undetected for a long time.

LYME DISEASE IN DOMESTIC ANIMALS

Lyme disease has been described in dogs, cats, horses cows and goats. Symptoms can include fever, lameness and soreness, listlessness, loss of appetite, swollen glands and joints. Heart, kidney, liver, eye and nervous system problems are also described in animals. Laminitis is reported in horses and cows, as are poor fertility, abortions and chronic weight loss. Temperament changes have been reported in dogs and horses. Untreated animals can develop chronic progressive arthritis.

Symptoms can be intermittent and vary in intensity from mild to quite severe and can mimic many other conditions. If you suspect Lyme disease in your animals consult your veterinarian as soon as possible.

This is where I got the info.
http://www.cs.cmu.edu/afs/cs.cmu.edu...saic/lyme.html
I hope you can get Duncan in to see the vet on Monday. If he does have the disease he will be started on antibiotics and within a month should be on his way to recovery. Please keep checking in so we may follow his progress.