aseptic meningitis in dogs
As I walked in the door to the clinic the other morning, one of my technicians came running down the hallway to meet me. Before I even had a chance to put my lunch in the refrigerator, she was bending my ear about her two-year-old Boxer. “It’s the strangest thing, Doc. He was fine just a few days ago, but now he seems really painful in his neck. He can walk fine, is eating and drinking, but he sure seems painful. Any ideas?”
Of course, I had a long list of possible ideas running through my head but decided that my best course of action would be to start with a physical exam and go from there. When it was all said and done, it turned out that her Boxer boy was suffering from aseptic meningitis (sometimes referred to as steroid-responsive meningitis). I decided that this would be an interesting topic for this blog, so here we go!
What is aseptic meningitis?
First of all, let’s talk about the meninges. The meninges are the three membranes covering the brain and spinal cord. Think of it as the skin of a tomato. The meninges serve to protect the central nervous system (the brain and spinal cord). Meningitis is inflammation of these membranes. The cause of the inflammation can be variable including infectious agents such as viruses and/or bacteria, trauma, and/or vasculitis. As you can imagine, there isn’t a lot of extra space within the skull and spinal cord for this inflammation. This results in pressure being applied to the underlying nervous tissue and results in clinical signs.
Aseptic meningitis is inflammation of these membranes that is NOT attributable to infectious agent or vasculitis. At this point, we don’t know what causes it, but there appears to be an immune-mediated component. This is most commonly seen in young medium to large breed dogs, and Boxers seem to be overrepresented. The clinical signs are severe neck pain and fever, without the clinical signs of other disease.
The diagnosis of aseptic meningitis involves a good physical exam, bloodwork to rule out other underlying causes, and analysis of the cerebral spinal fluid (the fluid that bathes the central nervous system). During the work-up, your veterinarian may recommend radiographs and/or an MRI or CT scan to rule out other possibilities.
Fortunately, most dogs afflicted with aseptic meningitis respond very well to treatment. The treatment involves a steroid regime with a very slow taper. Some dogs have to stay on a low dose of steroid long term in order to control the clinical signs, but they can live a happy, healthy, and normal life otherwise. There are a couple of other immune-suppressive medications that have been used with success, but steroids seem to be the drug of choice for most of these cases.
Don’t be surprised if your veterinarian places your dog on a good antibiotic during the steroid therapy. Some cases are not clear as to whether or not there is an infectious component, so concurrent antibiotic therapy may be warranted.
Fortunately, we were able to quickly diagnose my technician’s Boxer boy, and he has responded really well to his steroid regime. He is now back to his wiggly, butt-wagging, slobbering self!