Reviewed by Dr. Becker

Stevie, a one-year-old puppy raised with care, training, and patience, continues to unravel with growing anxiety and aggression. While the case centers on behavior, subtle signs of ongoing physical distress tied to what he eats and how his body responds are largely left unexplored.

Floppy ears, cute white patches, curly tails, shorter muzzles, and gentle behavior — you almost never see these traits in the wild. Why are domesticated animals different? Does that mean our pets have smaller brains, too?

Evidently, this gene mutation has been in the breed for a very long time. Virtually all tested dogs carrying two copies of the gene (both parents are carriers) are symptomatic. This is a progressive, heart-wrenching disease. So careful research is a must whether you're rescuing, breeding, or buying.