FORT WORTH, Texas -

A Fort Worth veterinarian arrested for animal cruelty Wednesday admitted in a handwritten statement that he secretly kept alive five dogs, including his own decrepit border collie, that should have been euthanized.

Dr. Millard Lou Tierce of the Camp Bowie Animal Clinic had his veterinary license temporarily suspended Wednesday by the Texas Board of Veterinary Medical Examiners on the basis of that admission and more.

Tierce was also arrested Wednesday on an animal cruelty charge, stemming from the lack of care given to his personal pet, a border collie kept at the clinic. He surrendered to the Tarrant County Sheriff's Department at about 7 p.m. Wednesday and was released soon after on $10,000 bond.

Tierce told NBC News Wednesday night he could not comment on the investigation, complying with his attorney's request. His lawyer did not return calls for comment on Thursday.

A hearing on Tierce's license's suspension will be held Monday in Austin before the state board's enforcement committee.

His arrest and suspension came a day after a family accused his practice of secretly keeping their dog Sid alive to provide blood transfusions to other dogs, months after he was to have been euthanized.

The family had agreed to euthanize Sid, a 5-year-old, 170-pound Leonberger, after Tierce diagnosed him with a congenital spine disorder. Six months after they agreed to euthanize their pet, they said a veterinary technician at the clinic reached out to them to let them know their pet was still alive.

According to the state board's temporary license suspension order, Tierce admitted that he had not euthanized five pets that had been accepted for euthanization, including Sid. The order did not say whether the other dogs were used for medical procedures like Sid allegedly was.

Dr. Michael Morris of the Fort Worth Animal Clinic determined Wednesday that three animals kept at the clinic were in such poor health that they needed to be euthanized.

Tierce said in his statement that one of those animals, a border collie, was his personal pet and that the other two had been left at the clinic to be euthanized along with two other animals. One of the other two animals had been kept in a cage at the clinic for as long as three years after being accepted for euthanasia, Tierce said.

In Tierce's arrest warrant affidavit, Fort Worth police and animal control officers said they found Tierce's black and white border collie lying in a box on the floor of an exam room. Police said the dog was twitching in pain. One of its legs was missing, another was dislocated and two of its shoulders were dislocated. A vet tech, identified as Cynthia Welch, said the dog had been in that condition, and largely in the same location, since she started working there on June 2, 2013.

Tierce admitted that the border collie was his dog and said he had provided the dog with only food and water and no medical attention.

Morris later determined Tierce's dog was emaciated and non-ambulatory, and that it was missing the bottom of a foot and had severe mouth disease, cataracts, a degenerative and untreatable neurological disease and abnormal overall health. It should have been euthanized, Morris determined.

Tierce said that in his professional opinion, he should have euthanized his border collie. Tierce was charged with animal cruelty, specifically for the lack of care given to his own dog.

Board's Order Describes Cluttered Clinic

The board said in its order suspending his license that Tierce could be a threat and a real danger to patients and that he had violated rules for minimum security of controlled substances.

Its order also detailed unsanitary conditions at the clinic, describing a cluttered setting with unsecured drugs "strewn about" and at risk of being abused.

"Animal organs were kept in jars throughout the clinic. Bugs were visible in exam rooms. Stacks of drugs, trash, laundry, paperwork and other miscellaneous items were strewn about the examinations rooms, hallways, stairwells, operating room, laboratories and offices of the clinic,” the documents said.

"Open and unsecured medications, including some controlled substances, were also strewn about the clinic and in such a fashion that controlled substances could easily be stolen and abused by employees, clients, or visitors of the clinic," they continued.

The Better Business Bureau of Fort Worth said there is only one complaint on his file within the last three years. The Fort Worth Police Department said only that its investigation continues, and the state's Board of Veterinarian Medical Examiners said it cannot comment on open investigations.

The Fort Worth Police Department said anyone who would like to file a report in regards to this case should call the FWPD nonemergency number of 817-335-4222 and explain they would like to make a report regarding the Camp Bowie Animal Clinic. They should also mention related report number 14-37697.

Clients Defend Veternarian

Numerous clients of Dr. Tierce showed up to the clinic to offer support to a man some have been bringing their pets to for decades.

“He wouldn’t do anything to harm an animal,” said Robert Heineman.

Heineman and his son Parker didn’t show up with any family pets but rather were at the clinic to support Dr. Tierce. They’ve been bringing their animals to the clinic for 30 to 40 years.