The owner of a Westport farm and 26 tenants who rented space on the property have been charged with mistreating about 1,400 animals in what authorities are calling the largest animal cruelty case in New England.

Attorney General Maura Healey said a grand jury handed up the 151-count indictment on Thursday, eight months after investigators found dogs, goats, horses, cows, and other animals at the Westport Tenant Farm living in squalid, overcrowded conditions, often without enough food or water.

Some of the animals were housed with carcasses while others were living in such deep manure that their hooves had rotted off, and they were suffering from painful eye, intestinal, and skin ailments, Healey’s office said. Many had to be euthanized while others were transported to other farms with severe injuries.

“This situation is unparalleled to anything I’ve seen in my 37 years as an animal law enforcement officer,’’ Lieutenant Alan Borgal of the Animal Rescue League of Boston said in a statement Friday. “The sheer number of animals in dire need of care, and the cruel and unsanitary conditions we found were deplorable.’’

The owner of the farm, Richard Medeiros, 83, was charged with 23 counts of animal cruelty. The 26 tenants were charged with between one and 11 counts each. Each count carries a penalty of up to seven years in prison.

In 2010, Medeiros was also charged with, but not convicted of, animal cruelty, after authorities discovered malnourished dogs, cows with open wounds, and dead calves on the farm. Several tenants were also charged in that case, including one named again in the most recent indictment.

Medeiros’s attorney, Karen Augeri Benson, declined to comment on the most recent case, saying she had not seen the indictment.

Medeiros told the Globe in August that he was unaware of the suffering on his 71-acre farm. “Where I could see, they all looked fine,’’ he said. He does not live at the farm, which is divided into 21 parcels rented to tenants.

R. Michael Sullivan, chairman of the Westport Board of Selectmen, said Friday that the town has worked to formulate policy and personnel changes that will prevent yet another cruelty case from happening.

Those changes include the hiring of additional animal inspectors, a review of the performance of town employees involved in farm oversight, and a civil legal action to prevent animals from being brought back to Medeiros’s farm until it can be cleaned and proper oversight can be ensured.

“Although we have made excellent progress on all of the aspects of our action plan, we are mindful of the fact that this is a real and difficult problem with which the town has struggled,’’ Sullivan wrote in an e-mail. “This is compounded by the fact that this problem has occurred twice in the past 7 years.’’

After the most recent cruelty case was uncovered in July, state officials ousted two Westport animal inspectors, saying the clean inspection reports they filed in January 2016 stood in stark contrast to the horrific conditions that had been festering on the farm for years.

Last year, a Globe review of the case, based on interviews, documents, and video recordings obtained by the paper, suggested that town officials failed to discover the deplorable conditions because of their own lax oversight of local farms. Some Westport officials, the Globe reported, were steeped in a centuries-old farming culture skeptical of intrusive regulations, and appeared to pay little mind to repeated warnings.

Shana M. Shufelt, a member of the Board of Selectmen, said officials want to improve communication among departments and strengthen the tracking of animal welfare cases. They may also launch a registry to document which properties have animals that need to be inspected.

In the past, she said, “nobody knew who was responsible for what.’’

Craig Dutra, the vice chairman of the Board of Selectmen, pointed out that the three-member Board of Health will have two new members taking office following an election next month. The new leadership, he said, will help “make sure we’re not going to be blindsided again.’’

Michael Levenson can be reached at michael.levenson@globe.com. Follow him on Twitter @mlevenson.