Seven horses, three dogs and a goat have been destroyed and more than 40 other animals taken into the RSPCA’s care after a farm was raided.
The charity swooped on White House Farm in Redbourn after receiving concerns from a member of the public about the welfare of animals kept there.
Firefighters were called to help assist in the two day raid in Hemel Hempstead Road, which took place on Tuesday, October 14 and Wednesday, October 15.
Staff from the animal welfare charity took 40 dogs, three horses and a cat into their care during the course of the two days.
In a statement, spokesman Katya Mira said: "Forty dogs, three horses and a cat were removed by the police and placed into the care of the RSPCA.
"On veterinary advice, a further seven horses and a goat had to be put to sleep at the scene and three dogs had to be put to sleep by a vet after being removed.
"The RSPCA has been monitoring and will continue to monitor the welfare of these animals.
"We would like to thank Hertfordshire Fire Service for their assistance during the evening of 15 October.
"As this is an ongoing investigation we cannot provide further information at this time."
Other animals - including horses, goats, chickens and dogs - remain on the site and advice has been provided by the RSPCA on their care.
Two fire engines from Hemel Hempstead and Redbourn were called to help remove the dogs just after 6.30pm last Tuesday.
Speaking on behalf of the service, Simon Hoggett said the two engines attended the raid as the shed where animals were housed had no light. The two crews used the generator from their engines to provide light, which allowed RSPCA officers to investigate.
Hertfordshire Police said that while officers assisted at the raid, no charges have been laid as it is a RSPCA investigation.