A Chicago physician reports that he had to abandon the use of dogs in an ulcer research program. The dogs refused to get tense & worry, & worry & tension are prominently listed as suspected causes of ulcers.
If you inflict an ulcer upon a dog by artificial methods, says the Chicago doctor, he will sit down & placidly cure himself by refusing to be bothered about anything.
Song Bird Songs 
Sometimes I forget about the poor animals being tested. So glad to know that dogs are chilled out. Actually I think my Sheltie was close to an ulcer. Just a bit on the hyper side of life.