Setting aside the notion of determining the number of individual animals on the planet for a moment, merely determining the number of species on the Earth is challenging. Science has only been able to offer estimates thus far, and totals vary greatly.
A. A. A. Multiple sclerosis, or MS, is a long-lasting disease that can affect your brain, spinal cord, and the optic nerves in your eyes. It can cause problems with vision, balance, muscle control, and other basic body functions. The effects are often different for everyone who has the disease.
Other diseases, such as feline infectious peritonitis, which can cause lesions in the brain, and brain tumors (something I, as a veterinary oncologist, frequently see), are also on the list of feline brain disorders associated with seizures.