Some vets have associated hypothyroidism with severe central nervous system signs but I have not personally seen this occur. (vetinfo.com)
Pups suffer a loss of appetite, yellowish diarrhea, trouble breathing, and central nervous system signs such as seizures, behavior changes, weakness, and incoordination. (thesprucepets.com)
The most frequently observed indications of the condition are such central nervous system signs as hyperactivity, disorientation, temporary blindness, and excessive salivation. (www2.vet.cornell.edu)