'Real World: Portland' Star Averey Tressler's Dog Dies

Averey Tressler -- a star of "The Real World: Portland" -- is dealing with a personal tragedy ... because her dog, Daisy, has passed away.

The reality star posted about her late pal Wednesday ... telling her more than 65K followers the pup passed away earlier this week.

Tressler asks for privacy ... but thanks fans for all the love they've shown her and Daisy over the years.

Fans of 'RW:P' will remember the dog from 2013 ... who found herself in the center of some drama when Averey flipped out on housemate Nia Moore for making "kissy" noises at her pup -- claiming it entitles the dog.

Plus, at a different point, Daisy turned the house into her own personal toilet ... doing her business wherever she darn-well pleased.