Cushing's disease (hyperadrenocorticism) causes chronic cortisol excess in dogs, producing a constellation of symptoms including muscle weakness, skin fragility, increased infections, and psychological distress.
Cushing's disease subjects dogs to the physiological effects of chronic stress hormone excess - the equivalent of living in a constant state of physiological stress response. The muscle wasting causes weakness and difficulty performing normal activities. Skin becomes paper-thin and vulnerable to injury. The compromised immune system leads to recurrent painful infections. The excessive thirst and urination disrupts sleep and causes anxiety. Many affected dogs develop a lethargic, flat affect reflecting the psychological impact of chronic cortisol excess. The pot-bellied appearance is caused by redistribution of fat and muscle weakening that is uncomfortable. Management dramatically improves quality of life, but requires careful monitoring to avoid the equally dangerous overcorrection of cortisol insufficiency.