This story contains details that are graphic in nature.

Former students in what was known on social media as @LovicLab at the University of Calgary say they witnessed the repeated "mismanagement" of the anesthetic given to rats during surgery.

Sources, who spoke on the condition of confidentiality, say that on many occasions the rats would wake up in the middle of a surgical procedure in excruciating pain, "crying, screaming and fighting."

One of the students says the negligent behaviour was reported to professors and the university's animal care committee starting in mid-2017, but the alleged inhumane treatment continued for several more months.

The university says the animal care committee never received a formal complaint on the matter in 2017.

CBC News has attempted to contact the professors identified by sources, but there has been no response.

Assistant professor Vedran Lovic is on leave from the University of Calgary. (University of Calgary )

The lab was under the supervision of assistant professor Vedran Lovic, who received a $100,000 grant from the Canada Foundation for Innovation in 2015 to study the mechanism in the brain that makes some people more prone to addiction.

The lab was abruptly shut down this March.

The students say that on one occasion a tank used to administer anesthetic was empty due to negligence and the animal woke up during a jugular catheterization. They say the student performing the surgery continued on with the operation while the animal was in distress, using a surgical pad to restrain it.

They say the animal's back and neck had been cut open when it woke up during the procedure and they say it happened on so many occasions that "everyone at some point saw something."

The University of Calgary's department of psychology faces a 'professional climate review' in the fall. (Bryan Labby/CBC)

Lovic went on leave from the university in December 2017. The school would not comment when asked about Lovic's leave, referring to it as a personnel matter.

Students say the lab was abruptly shut down March 5 after the university's head veterinarian started looking into the complaints.

The university issued a statement to CBC News, attributed to Dru Marshall, provost and vice-president, academic:

"The University of Calgary is aware of concerns raised about operational procedures in a specific lab in the department of psychology. These concerns are being taken very seriously and are being reviewed. During this review process, we have focused on gathering information to ensure completeness and accuracy. To protect the privacy of those involved, we will not be making any other public comment at this time. Once our review is complete, if necessary, the university will make changes to ensure that our procedures continue to be upheld to the highest standards. Until then, the lab remains closed. A lab closure impacts research being conducted, and we are working to minimize any impact experienced by our students as a result of the lab closure."

A student who says she worked in the lab from November 2015 to the time it was shut down says she never saw any rats wake up during surgery.

She spoke to CBC News on the condition that she not be identified.

"[I] never witnessed any animals wake up because they weren't given enough anesthetic," the student said.

"Someone made false accusations of that, but an investigation was done and found that to be incorrect. I am very familiar with animal surgeries and the nature of these completely false accusations."

The statement from the university, however, indicates the review is currently underway.

CBC News has made multiple attempts to contact Lovic but hasn't received a reply.

Professional climate review

It's not the only issue facing the department, a separate review was launched following the sudden resignation of department head Chris Sears.

"I know this will come as a shock to many of you. But as a department, we need to move forward in a different way," Sears wrote in an email to students and faculty.

Sears says his decision was prompted by a lack of unity in the department and not related to the lab investigations.

Chris Sears resigned as head of the department of psychology on July 19. (University of Calgary)

"I was excited to begin the position last July, and keen to launch our strategic planning exercise to map out our plan to become a top 10 department. I am grateful to everyone who worked with me during the past year to move our department toward this goal: faculty, staff, and students.

"Unfortunately, as a department it has become difficult for us to focus on this objective, and we do not have the unity necessary to continue. My plans and aspirations are not realistic at this time. I have therefore decided to resign as department head, effective immediately."

The faculty of arts dean said this in an email to students:

"In the fall term, 2018, a professional climate review will be conducted in the department. The dean's office and human resources staff will work closely with interim department head Dr. Keith Yeates and the department during this process. Subsequently, in the 2019-2020 academic year, there will be a full search for a new head."

A day before Sears' resignation, the faculty of arts dean held "an informal discussion" with the department's graduate students.

The email did not mention any specific issue or reason for the meeting.

In an email to CBC News on Sept. 21, Sears said his resignations "had nothing to do with the lab investigations or the meeting with graduate students," he wrote.

Anonymous student survey

The Psychology Graduate Students Association launched an anonymous survey saying "there have been concerns about how all of these events have been handled and communicated to students."

Screenshot of an eight-question survey launched by the Psychology Graduate Students Association on July 20. The link to the survey has since been closed. (Psychology Grad Students Association website)

The association says it will collect and collate the feedback and put together a "course of action moving forward."

CBC News tried to contact the association but didn't receive a response.

The president of the university's Graduate Students' Association did respond to a request for comment. She says the association's role is advocacy and support for students affected by the closure of the lab.

"We want to ensure that our graduate students have a safe and respectful learning, teaching and working environment in which they can conduct their research," Brit Paris said, but she would not comment on any of the allegations surrounding the department, citing student and faculty confidentiality.

The closure of the lab has left several students scrambling to continue their research and in some cases they are making plans to leave the university.

Bryan Labby is an enterprise reporter with CBC Calgary. If you have a good story idea or tip, you can reach him at bryan.labby@cbc.ca or on Twitter at @CBCBryan.