Spondylosis of the Lumbar Spine
This is a fairly common disease of rabbits over 4 years of age, particularly females of medium to large breeds.
Cause: The vertebrae in the lumbar or back area gradually develop little bony protrusions that can eventually bridge to the adjacent vertebrae resulting in the fusion of the two. No one knows the exact reason this happens, but it is likely an aging process. It can be aggravated if a rabbit is carrying excess body weight (obese). This is not life threatening and can progress for years.
Signs: The fusing of the vertebrae decreases the flexibility of the spine and prevents the rabbit from being able to jump and run as easily. Before these bony "spurs" fuse completely, they can rub on each other and cause some pain. The pain may come and go dependent on things such as the weather and how much exercise the rabbit got the day before. Rabbits affected with this disease "shuffle" rather than hop and on some days can become very reluctant to move at all. As the disease progresses, it may be difficult for the rabbit to get in and out of the litter box and he may soil himself.
⇒ Read more about spondylosis by Susan Brown, DVM.