Source:
WFTV.com OrlandoLongwood, Fla. -- A Longwood veterinarian has been successful with a treatment to counteract the poison that some believe is making pets sick.
snip...
The New York state food lab claims aminopterin is the contaminant that’s making animals sick.
snip...
Jenner’s brother is a research scientist, and knew aminopterin’s history. He told Tara about another drug, Leucovorin, which was used in the U.S. when aminopterin was used as a cancer drug, to counter-act the negative effects of it.
snip...
After two days of the Leucovorin treatment, Holly's kidneys were back to normal.
Read more:
http://www.wftv.com/news/11459819/detail.html
The article says Leucovorin is a potential treatment for dogs sickened by aminopterin-contaminated food, but is probably too strong a drug for cats to handle.
Also, props to Kestrel for reporting on Leucovorin's possible benefits back on March 23:
http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=102&topic_id=2778351#2778625