Racing a two-year-old horse is the developmental equivalent of racing a 13-year-old child, according to a Wagga horse psychology academic.
Charles Sturt researcher Rachel Hogg said it was an increasingly common practice in the industry, spurred by a financial incentive to start making money from the horses as early as possible.
Dr Hogg said some parts of a horse's body develop rapidly, but that other parts such as the spine and the legs do not fully mature until the age of six.
She said cartilage in a horse's knees don't fuse until around age two, with research suggesting that about 40 to 80 per cent of two-year-old racehorses develop painful shin soreness.
Dr Hogg said that most horses begin training in childhood between 18 to 20 months of age, well before the skeleton has finished developing.
"We tend to think that when a horse looks fully grown, it is fully grown, and that is not the case," Dr Hogg said.
"Racing two-year-olds was almost unheard of 40 years ago, so there's every reason to think that this practice isn't integral to the continuance of horse-racing today."
However for older horses Dr Hogg said vigorous exercise does lead to better health outcomes, with stronger skeletons, resistance to injury, and overall healthier horses.
Dr Hogg said she would even go so far as to say that some racehorses led "incredible lives", but that that was definitely not the case for the majority of cases.
"The conversation around horse welfare that is commonly presented is that race horses are treated really, really well and are cared for better than the average horse would be," Dr Hogg said.
"That's absolutely true - for a minority of horses. The horses that are not successful, or are successful for a short period of time then retire, have very different fates.
"Does the luxury given to a select few justify the consequences for the rest? That's the question the public have become much more aware of in the last 4-5 years."
Murrumbidgee Turf Club chief executive Steve Keene said racing two-year-old horses was not common in Wagga, saying it was only done in certain special cases.
"Like children, horses all mature and grow at different stages in different ways. A one-rule-fits-all policy doesn't fit for this case, and horse trainers all put animal welfare first," Mr Keene said.
"If they feel their horse isn't mature enough for the strenuous work of trackwork, they'll be the first ones to put them out in the paddock and let them fully mature and develop."
Mr Keene said their trainers genuinely cared about the welfare of their animals, insisting that "money doesn't play a part in it".
"That's why you do see there's not a lot of two-year-old racing around, because those trainers are quite mindful of equine welfare," Mr Keene said.
"We have a limited amount of those each year. It is at the lower end of school of the type of racing we hold."
A copy of Dr Rachel Hogg's article can be found on The Conversation's website.