'Yellowstone's Dawn Olivieri Sues for Defamation Over Claims of Horse Abuse

Dawn Olivieri's fighting back against claims she abuses horses ... suing numerous people who she claims made false statements that have negatively impacted her livelihood.

Olivieri -- a star on the hit show "Yellowstone" -- filed the lawsuit last month claiming a bunch of people have made false statements about her in order to damage her partnerships with third-party organizations and businesses.

Dawn says she had a campaign all set up with clothing giant Dickies -- posting promotional pics to social media -- when, she claims, users engaged in a coordinated effort to kill her brand deals.

According to DO ... numerous horse-related influencers have publicly made false claims that she's forced horses at her sanctuary, Moon Mountain, to drink dirty water ... that she's supported the starving of horses ... and has killed newborn Arabian horses.

Olivieri says her campaign with Dickies has fallen apart because of these claims, and it's affected other brand partnerships as well.

There are a ton of different claims ... but, bottom line, these influencers say Moon Mountain's methods and care have led to numerous dead horses -- an assertion Dawn calls B.S.

Worth noting ... Dawn says she's tried reaching out to the defendants personally -- but, they're not slowing down with their claims, and Dawn's now suing them for damaging her reputation and hurting her brand deals.