Here is a brief summary of the two main issues that need to be addressed in regard to the horse meat industry in Australia:
1. Human Health
Horses in Australia are routinely treated with medications, feed additives and even products such as insect repellents that have "NOT TO BE USED ON HORSES THAT MAY BE SLAUGHTERED FOR HUMAN CONSUMPTION" written on the label.
Horses slaughtered for human consumption are not bred for this purpose, and as such their owners and trainers use these products without a second thought. For example, if you want a racehorse to be a winner, of course you will do whatever necessary to keep it fit and healthy. While the horse is still racing there is no problem, but what happens if that horse is too slow, and ends up being put through an auction only to be purchased by a meat buyer?
In Australia there is no system of tracking individual horses and the medications, etc, that they have been given throughout their lifetime. It is difficult even to track down information about who may have owned the horse in the past, let alone what treatments it may have received.
There is no legal requirement for any horse owner to report the use of any medication on any horse. Under the current system, for Australian horse meat to be safe, each individual horse must be tested for toxic and carcinogenic substances in their system.
One very commonly used drug that is of major concern is Phenylbutazone, known in the horse world as "bute". It is used by many horse owners as if it is "horsey panadol", given to horses whenever there is even the slightest thing wrong with them. One of the key reasons why Europe introduced a system of horse "passports" was to track the use of Phenylbutazone, which is not safe for humans to consume at any level in horse meat. Until such a system is introduced in Australia, there are serious risks to human health in bringing horse meat to the table.
(In the case of the horses slaughtered for Vince Garreffa, the WA Health Department "screened" the horses to ensure they were safe. The exact screening procedures are not known to me at this point, despite repeated requests for this information (I will update this if my questions are answered at some point.) If the screening involves such measures as background checks or blood tests on each horse, this would seem to be a ridiculously unsustainable method of ensuring food safety... particularly bearing in mind that other butchers will no doubt also wish to start selling horse meat.)
2. Inhumane Slaughter Technique
Without going into unpleasant details... The method of slaughter used on horses intended for human consumption is designed for cows, not horses. Horses are not effectively "stunned" in the same way as cows, due to the different shape of their skulls. This results in them suffering terribly in the slaughter process.
A humane technique has yet to be found, and this has led to horse slaughter being banned in the United States.
If you can handle the unpleasant details, please click here or here for more information. (These links are from the USA, but the technique is the same as that used in Australia.)