What this means, is that animals have no independent rights of their own because they are objects, chattel or things under the law. They are 'owned' by human beings who have absolute control over how they are treated.
This is the same way that we used to treat slaves. Historically, in certain societies such as Ancient Egypt, Ancient India and Homeric Greece, the rights of an owner were so absolute that they included the right to kill one's slave.
Today, an owner's rights over animals are not absolute and they have been restricted via various legislation. The Prevention of Cruelty to Animals Act in Victoria ensures that animals will not be subjected to cruel treatment. For example, owner's are not allowed to engage their 'property' in live animal fighting or baiting. They are also not allowed to breed pit bulls or have dogs unsecured in trays of moving vehicles. Legislation can also enforce positive obligations and force owners to register their pet such as in Queensland under the Animal Management (Cats and Dogs) Act 2008.
Farm animals, however, are totally exempted by cruelty legislation and it does not apply to them. This means that various practises such as unanesthetised de-beaking of egg laying hens done by a hot blade, the unanesthetised de-horning of milk cows which causes them to bleed for up to 12 hours and scream in pain, and the unanesthetised de-teething of piglets - would be illlegal if done on a cat and dog. This exemption for farm animals, based on 'economic necessity', shows just how ineffective our current legal protection of animals is. Scientific evidence shows that farm animals suffer intense pain when subjected to the above routine practises - but we have the inhumanity to continue to put them through this pain - and their legal status as property allows us to do this.
The treatment of animals as property refuses to recognise their sentience - that like us, they have the capacity to think, feel and most importantly - suffer. Instead, because we legally treat animals as property we facilitate the widespread explotation of animals in Australia who are denied many important protections under our law.
There is an alternative to this model. What is needed, is a legal framework which recognises that animals are sentient and can feel pain. We need a system that does not automatically prioritise the rights of humans above animals. This can be done in a number of ways. Francione wants us to absolish the property status of animals and grant them rights. These rights would depend upon the animals - for example a chicken wouldn't be given the right to drive a car or vote. This could be done incrementally. Rights could be enforced through independent animal lawyers, private persons or animal protection socities.
Another model of moving towards better legal protection for animals is suggested by Favre. He advocates a guardianship model over animals which is similar to the way we treat children.
Current legal protection for animals if speciest and refuses to recognise the sentience of animals adequately.