The unidentified woman told police she was watching television in her home Saturday night with the shotgun by her side, and it fired when the dog bumped it.
She sought treatment for her injured left foot the following morning, the Fort Worth Star-Telegram reported Monday.
"The victim advised it was an accident and the dog was not to blame," said officer Sharron Neal, a police spokeswoman.
Police did not identify the breed of the dog.
"He has the right to remain silent," Neal said.