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U. of I. veterinarians build better 'mouse trap' for enhanced diagnoses

Robert O'Brien
Photo by
L. Brian Stauffer

Robert "Bob" O'Brien, professor and head of diagnostic imaging in the College of Veterinary Medicine, demonstrates his invention, the VetMouseTrap™, with his cat Michael.

« Click photo to enlarge

3/30/2011 | Sharita Forrest, News Editor | 217-244-1072;

CHAMPAIGN, Ill. — Veterinary radiologists in the College of Veterinary Medicine at the University of Illinois recently obtained what are believed to be the first 3-D internal renderings of dogs’ larynxes by using a restraint device they created that allows clinicians to perform CT scans on awake small animals without chemical restraint.

The device – which is being tested by veterinary radiologists at universities in Australia, Europe, South Africa, and the U.S. – is a significant advance for veterinary patients, enabling faster diagnosis and more effective treatment of life-threatening diseases such as laryngeal paralysis and laryngeal collapse in dogs, and asthma, heart failure and certain cancers in cats.

The device, the VetMouseTrap™, provides a low-heat, comfortable and nurturing environment for small pets that safely restrains them without the risks of sedation or anesthesia.

The VetMouseTrap™ is a Plexiglas tube with a removable top and foam padding in the bottom that limits patients’ motion, keeping them in a neutral sternal position so clinicians can conduct CT scans. Once the patient is inside the VetMouseTrap™, clinicians fasten it to the CT table with Velcro straps.

The tube’s rounded shape doesn’t create “artifacts” on the CT images, one of 16 criteria that the team identified when it set out to design a restraint device for cats, said Robert T. O’Brien, professor and head of diagnostic imaging in the department of clinical medicine at the veterinary college and leader of the research team.

Accordingly, the transparent acrylic material of the VetMouseTrap™ permits staff to visually monitor patients inside it, and the device closes securely, but has no metal buckles or hinges, keeping the animal contained while allowing quick access to them if needed. Removable padding allows the device to accommodate small patients of different body sizes and behavioral characteristics.

The design is also symmetrical, with ports in each end to accommodate intravenous catheters and oxygen lines so that clinicians need not disconnect and reconnect lines when inserting or removing patients.

“Our goal with our imaging with the VetMouseTrap™ was to provide a higher level of imaging with the lowest cost and the least effects on our patients – without any anesthesia or sedation – so that we can provide that information to the client and the clinician without the need for more advanced, and usually more expensive, procedures to be performed,” O’Brien said.

“That’s not to say that CT is cheap – it’s just extremely quick. What it does more than anything else is give us confidence in the diagnoses and allow us to aggressively treat conditions with a high degree of accuracy. That is in the best interest of the client and the patient. And I hope, in the end, it means more animals will survive their diseases. Mortality is at issue here – these aren’t diseases that animals always get well from.”

A single CT scan of a cat can be obtained in 15 seconds or so, while small dogs take a few seconds longer, O’Brien said. “Sometimes we have to do multiple images of dogs to figure out where their airway problem is, but we can usually be done within five minutes. This is very fast imaging. And the animals are totally awake and not being restrained or anesthetized.”

During the study’s initial phase, the VetMouseTrap™ was tested with 10 healthy cats – a mixture of outdoor and indoor cats – and the cats’ breathing rates and other responses to being inside it were monitored. Only two cats – both of them outdoor cats – showed signs that they were so distressed about being inside the device that they had to be removed. The remaining cats “didn’t appear to be stressed any more than they would be just from being in a strange place,” O’Brien said.

Images of 22 diseased cats, and then of 16 dogs with symptoms of primary laryngeal or tracheal airway obstructions, were obtained using the device.

“We had a very good correlation between what we saw on this advanced CT imaging and the final answers that they were able to get surgically or with endoscopic evaluation, which is the gold standard,” O’Brien said. “This level of detail has never been seen before in veterinary medicine.

We had no imaging modality to image inside the voice box of a dog. It was just not possible. Radiographs couldn’t do it. And even if you did CT, MRI or one of the advanced modalities, you had to place a tube down through the voice box. Then you couldn’t image what you’d just placed the tube down.”

Sedation and general anesthesia are especially dangerous for animals in respiratory distress, and veterinarians have had to weigh the hazards of chemical restraint against the possible diagnostic benefit of CT imaging. Some dogs also have trouble awakening from anesthesia and require an emergency tracheostomy – a surgical procedure where a hole is cut into the dog’s trachea to help it breathe – and sometimes the tracheostomies are required permanently, O’Brien said.

Rabbits and cats, which respond to pain and stress by hunkering down and not moving, “are perfect candidates for the VetMouseTrap™,” O’Brien said. Large dogs, which usually try to escape confinement by frantically barking and digging, are not amenable to it.

“It’s not a best fit with every patient, but it’s worked with almost every cat and with many small dogs,” O’Brien said. “We think there’s a lot of opportunities in other species.”

Researchers in England and Scotland are exploring modifications to the VetMouseTrap™ for general practice veterinarians there, where radiation safety laws prohibit technicians from being in the same room to restrain animals when scans or X-rays are performed, O’Brien said.

The device also has other clinical uses, such as portable oxygen delivery to awake cats that need oxygen therapy, but not necessarily diagnostic scans, in the U. of I. Small Animal Clinic’s emergency room, O’Brien said.

Britain’s Princess Anne, who is patron of the Royal (Dick) School of Veterinary Studies at the University of Edinburgh, was photographed examining and talking with faculty researchers about the VetMouseTrap™ during a visit to the school, O’Brien said.

The U. of I. has patented the VetMouseTrap™ and entered into a contract with Universal Medical Systems in Solon, Ohio, to manufacture and market the device as a portable oxygen delivery device for cats. The company also plans to include the device with every veterinary CT scanner it sells. The first 10 units were expected to hit the market April 1, according to the company’s president D.R. Zavagno.

“The introduction of the MouseTrap is a significant improvement and opens the door for an area of imaging not currently service by any other method,” Zavagno said. “Far too often we are using human CT scanners with very little transition for animal specific protocols and imaging requirements. The end result is poor resolution, fair quality, and underutilized installations. The cat trap will be one of the first specific improvements for veterinarians using technology designed for animals.”

Articles about the team’s work with the VetMouseTrap™ have been accepted for publication in the journal Veterinary Radiology and Ultrasound.

Editor's note: To contact Robert O’Brien, email; 217-778-2256.
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