Dear Dr. John,

I have a friend who has a young puppy that was recently diagnosed with something called MUO. What is this and how serious is it? She told me that her dog was in critical condition, and the prognosis was not very good. The puppy was disoriented and had had a seizure which prompted the visit to the emergency center. My friend was also informed that it might be touch and go for the next few weeks or months. She is considering putting the puppy down since the situation is so challenging. What should she do? I informed her that I would reach out to you. J.F.

Dear J.F.,

Thanks for your confidence in allowing me to weigh in on this. MUO stands for meningoencephalitis of unknown origin and can present with different degrees of severity. This is a broad term used to describe inflammatory diseases of the central nervous system that are usually immune mediated. There is no specific cause, and the name is given to dogs that are diagnosed with clinical signs that then have follow up diagnostics that cannot identify bacteria, viruses, fungal infections and other causes.

Dogs, like other species, can unusually develop diseases in which their immune systems attack their own bodies. In MUO conditions, the central nervous system comprising the brain and the spinal cord is attacked developing inflammation that leads to the clinical signs associated with it. These signs can vary widely and include disorientation, various nerve deficits, loss of vision, vestibular signs leading to loss of balance, neck and back pain, and even seizures. Treatment is given based on symptoms and corticosteroids is the first line of treatment. Cyclosporine and other medications are also utilized to lower immune system activity.

The information your friend was given was accurate in that a quarter to a third of those affected die within a few weeks or months but those that respond well to early initiated treatment can go on to live normal and long healthy lives. As such, I would not suggest euthanasia and hope for the best.

Dr. John de Jong is President of the World Veterinary Association. He owns and operates the Boston Mobile Veterinary Clinic and can be reached at 781-899-9994.