Crystal O'Toole says she returned to her Kangaroo Flat home Friday morning to an open gate and a dog that could not walk.

"Normally I pull up in the car and he is so excited to be there and I will see his little nose poke under the gate," she said.

"On Friday, he was so excited to see me, he was wagging his tail. All he wanted to do was cuddle me but he couldn't walk.

"Someone's definitely hurt him. I spoke to the vet again this morning and she is pretty certain he has not done it himself."

Ms O'Toole's partner has also noticed two of his tools are missing.

He had left them in the backyard overnight as he had been working on a project, she said.

Both the missing drill and impact socket wrench are red and black Snap-on brand hand tools.

They are estimated to cost $700 each when part of kits.

Ms O'Toole does not know whether the intruder entered the backyard intending to hurt Rolo.

"He is the sweetest little thing and he loves humans so much, so if someone has come in to steal something he has probably gone over to see them and say hello," she said.

"They might have got a fright and kicked him."

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The couple believe someone must have entered the backyard sometime between 2.30am and 6am.

A vet has told Ms O'Toole Rolo's leg has been badly damaged and will likely require major surgery.

"He can't put any pressure on it. The vets said the only way he is likely going to be able to walk again is to get surgery done and it's going to cost $3500-$4000."

Ms O'Toole will meet with a surgeon on Monday to discuss options.

The couple want to warn others to be on the lookout and to be aware of the risk to pets.

They have filed a report with police.

Anyone with information should contact Bendigo police on 5448 1300 or call Crime Stoppers on 1800 333 000.

A crowdfunding campaign has begun to cover some of Rolo's medical care. To learn more, click here.