In an e-mail to members of the state Dog Law Advisory Board, her supervisor, Michael Pechart, a top aide to Agriculture Secretary George Greig, said he would temporarily replace her as dog law director.
Animal-welfare activists had called for Diehl's removal, contending advancements made during the Rendell administration to clean up the state's puppy mills appeared to be eroding.
"For the year that she ran the office we weren't seeing inspections conducted properly or citations being issued, and regulations were being ignored," said Tom Hickey of West Chester, a member of the Governor's Dog Law Advisory Board.
When asked about Diehl's transfer and the plans for finding a replacement, a Department of Agriculture spokeswoman said only that it was "a personnel matter."
Diehl's predecessors, former bureau director Sue West and special deputy secretary Jessie Smith, had both served on boards of humane societies. As a lawyer in the Attorney General's Office, Smith also had extensive experience with state laws and regulations. Both were removed from their jobs after Gov. Corbett took office.
At the April meeting of the Dog Law Advisory Board, the first since Corbett took office in January 2011, Diehl acknowledged that only 17 of 52 commercial kennels were in compliance with the strict canine health regulations for commercial kennels, which require ventilation systems, improved lighting, and monitoring for temperature, humidity, and ammonia levels.
In addition, many kennels were given repeated warnings for dog law violations over the last year, but state inspection reports show no citations were issued to commercial kennels until recently.
Diehl also approved a kennel license for the wife of Lancaster County breeder John Zimmerman after his license was revoked because of an animal-cruelty conviction.
Animal-welfare advocates protested the license because they said it violates the dog law provision against transferring licenses to family members of those convicted of cruelty.
Contact Amy Worden at 717-783-2584 or aworden@phillynews.com, or follow on Twitter @inkyamy.