Whoever defaced a Brisbane billboard depicting animal cruelty in the greyhound racing industry for the second time in two weeks is "pretty desperate", Animal Liberation Queensland (ALQ) says.

The billboard, which overlooks Sandgate Road at Virginia on Brisbane's northside, was defaced overnight on Saturday.

Words and letters in the billboard's message "Ban greyhound racing. Cruelty doesn't deserve a second chance" were painted over to read "Greyhound racing does deserve a second chance".

ALQ President Chay Neal said it was the second time the billboard had been defaced in two weeks.

"Pretty desperate people, I think," he said.

"The good news is it won't cost Animal Liberation or our supporters a cent.

"The billboard company has been really good in replacing the billboard as soon as possible.

"And as a result of the downtime in between replacing skins we're hoping we'll get a free month, so it will just be more exposure for us."

Billboards 'a reminder of live baiting and cruelty'

Mr Neal said it was clear that people associated with the greyhound racing industry wanted to hide the message.

"Animal Liberation thinks that the greyhound racing industry has had more than a fair shot, and it should be shut down.

"Things like live baiting have probably just gone further underground.

"There's certainly police and even people from the industry that have admitted that they've got no guarantee that it's stopped, or that it won't start again.

"So the billboards are up there to remind people about live baiting and the cruelty in the industry."

Mr Neal said those who did it must support the industry's illegal practices.

"Whoever did this supports live baiting, which I think is just atrocious" he said.

"We put up these billboards to draw attention to what was exposed twelve months ago, the atrocities of live baiting, and the cruelty involved.

"The fact that someone has gone and defaced that billboard really implies that they support that absolutely abhorrent behaviour."

He said the billboard company had made a complaint to Queensland police, and hoped those involved were caught on CCTV.