Figures for the first quarter of 2013 reveal a sharp drop in the number of American horses going to slaughter in Mexico.
The fall in numbers follows the horse-meat contamination scandal in Europe, which resulted in tens of millions of ready-to-eat processed beef products being pulled from supermarket shelves in at least 12 countries.
The scandal cast a spotlight on the complexity of the food chain and revealed its vulnerability to rogue traders.
The Equine Welfare Alliance says the flow of horses south to Mexico had been increasing steadily for over two years, but dropped 62 per cent between the first full week of 2013 and the end of the first quarter.
Since the closing of the US based horse slaughter plants in 2007, US horses have been going to slaughter in Canada and Mexico for consumption in the European Union (EU) and Russia.
The alliance, an umbrella group for more than 280 horse advocacy organisations, said available data indicated that the consumption of horse meat in EU countries was flat to down over the past decade, but the export of US horses kept climbing.
Sales of processed beef products have dropped in the EU in the wake of the scandal, the alliance noted, but the consumers of horse meat in the EU were unlikely to change their buying patterns since they were intentionally consuming it all along.
Representatives John Holland and Vicki Tobin said the current trend did not bode well for fledgling companies trying to bring slaughter back to the US.
Data on the export of horses to Canada for slaughter will not be available for 60 days, but reports in the Canadian media indicate an even more severe drop in the number of US horses being slaughtered in Canada.
The export of horses to Canadian slaughter had already been on the decline in 2012 when it dropped by 7.5 per cent, but this was more than offset by a 61 per cent increase in horses going to Mexico.
The reason for this shift to Mexico is thought by some to be attributable to the fact that Mexico does not test for phenylbutazone contamination.