Is house trained hypenated?
Also are laid-back and low-key hypenated?
You can look these words up in a dictionary.
http://www.onelook.com/
Yes, to the extent of my knowledge, they are all hyphenated.
To determine whether a compound word like "house trained" is hyphenated, you can consult a dictionary or a reliable style guide. In this case, "house trained" is indeed hyphenated.
Similarly, for the words "laid-back" and "low-key," we can consult a dictionary or style guide. These words are commonly written with a hyphen, so "laid-back" and "low-key" are the correct forms.
In general, hyphenation rules may vary for compound words, and it is always best to consult a reference source for guidance.