Someone else might be able to chime in more specifically, but the ALF are a decentralized and militant animal liberation group that is known to participate in direct action. They’ve been labeled a terrorist group for their actions against animal agriculture. One thing they’ve done is free beagles (and other animals) from animal testing labs, as beagles are very obedient dogs and are tolerant of higher levels of abuse, so are frequently experimented on. I’m assuming the banner is one specific time they did that.