CAHF Research Grants: 2016-2017

Combined CT and MR scan will help researchers pinpoint the location of a tumour. Photo by Christina Weese.

Combined CT and MR scans will help researchers pinpoint the location of a tumour. Photo by Christina Weese.

The WCVM Companion Animal Health Fund (CAHF) has provided financial support for four pet health research projects that will be conducted by research teams at the regional veterinary college during the next year. Read the following research summaries for more details about each study.

Can combined CT-MRI images help to accurately define brain tumours in cats?

Drs. Monique Mayer, Jerome Gagnon, Gillian Muir and Cheryl Waldner, (WCVM); Dr. Keijiro Shiomitsu, University of Florida; Drs. Hiroto Yoshikawa and Elissa Randall, Colorado State University

When a cat develops a pituitary tumour, it can take up to 20 or more sessions of conventional radiation treatments to treat the growth next to the brain. For each session, the pet must also be put under general anesthetic.

A newer, more effective method of radiation therapy is stereotactic radiation therapy (SRT) that uses intense, highly targeted radiation beams and only requires between one and five treatments of radiation. Radiation oncology teams can use the new technology to define the size and volume of the tumour, but because SRT delivers high doses of radiation, specialists must be very careful to avoid exposing normal, surrounding tissue.

A team of veterinary scientists in Canada and the United States, led by WCVM researchers Drs. Monique Mayer and Jerome Gagnon, aim to obtain the most accurate information available before performing SRT. Many radiation treatment facilities only have access to computed tomography (CT) images, which provide limited details of the brain and surrounding tissue as well as the tumour. The team plans to combine CT and magnetic resonance (MR) images to more accurately delineate normal structures that need to be avoided. The images will also help to determine the difference between CT and MR in accurate calculation of the full extent of a tumour.

The team will conduct CT and MR scans on 20 cats. Next, they will fuse the two types of images together and identify consistent markers on CT that can be used as guides by oncology teams that do not have access to MR imaging. Once the fused images have been created, the researchers will also consult with a group of oncologists and radiologists to reach a consensus on the exact extent of normal structures.  The delineation of tumour will also be compared between CT and MR imaging, to see what effect the use of CT alone could have on accurate identification of tumor extent.  Overall, the researchers hope their study’s results will lead to more accurate treatment for feline pituitary tumours.

Can a serum biomarker identify dogs that are more prone to side effects?

Dr. Jerome Gagnon, WCVM

When veterinary medical oncologists develop a treatment plan for a dog with cancer, their goal is to maintain a high quality of life for the animal for as long as possible. Most dogs react well to a chemotherapy drug called carboplatin, but some develop unfortunate side effects that include anorexia, vomiting and diarrhea. Some dogs suffer more severely than others due to kidney disease or decreased kidney function. Kidneys play an important role in excreting chemicals following chemotherapy, so when a dog can’t properly eliminate the chemicals through its kidneys, it can develop these side effects.

In this study, WCVM medical oncologist Dr. Jerome Gagnon is investigating one method of identifying canine patients with kidney disease or decreased function before administering carboplatin. A new serum biomarker, symmetrical dimethylarginine (SDMA), is a small molecule that is also excreted through the kidneys. Gagnon plans to administer SDMA to some of his canine patients before beginning carboplatin therapy. Based on the results of recent studies, he expects to find higher levels of SDMA in dogs that also suffer from the side effects of carboplatin.

If the project’s results support Gagnon’s hypothesis, the research will help medical oncologists determine which dogs are at a higher risk of developing side effects after carboplatin treatments. In future research, Gagnon hopes to continue his research by giving lower doses of carboplatin to dogs that showed high levels of SDMA to see if they experience fewer side effects.

How efficient is the “flow-by” oxygenation method?

Drs. Barbara Ambros, Maria V. Carrozzo, Teela Jones and Carolina Palacios, WCVM

All canine patients must have ample oxygen reserves in the lungs before undergoing general anesthesia. Without these reserves, oxygen can’t flow to important tissues in the body while the patient is unconscious. Oxygen can be administered to dogs through a face mask, but dogs will occasionally struggle to avoid the mask and become anxious. When a patient is stressed and breathing heavily before anesthesia, the animal isn’t gathering enough oxygen reserves.

To avoid this issue, anesthesia specialists will hold an oxygen tube one inch from a dog’s nose to allow for relaxed respiration. While this “flow-by” method is less stressful for the animal, anesthesia specialist Dr. Barbara Ambros and her research collaborators suggest that this practice is less effective. They believe that dogs don’t take in the same amount of oxygen as they would with a face mask because the oxygen is diluted by air in the room.

A comparison between the two techniques has never before been tested, so Ambros and her team will test the efficacy of “flow-by” oxygenation in this study. The researchers will monitor oxygen levels of dogs using face masks or the flow-by method before and during anesthesia. Results from this project will be immediately applicable to clinical practices and will have an impact on daily anesthetic management and patient care.

How do bacteria become resistant to antimicrobial drugs?

Drs. Joseph Rubin and Roshan Priyantha, WCVM

Staphylococcus pseudintermedius is a bacterium that’s commonly found on the skin and other soft tissue areas of household pets. While it’s harmless to healthy dogs, this bacterium can cause skin and urinary tract infections if an animal’s immune system is weakened.

Unfortunately, due to the emergence of antimicrobial resistance, veterinarians have a difficult time treating these common infections. Because of this resistance, scientists are increasingly looking to older medications such as the sulfa (sonfonamide) drugs, which fell out of favour as new drugs were developed. The sulfa drugs are folate synthesis inhibitors and kill bacteria by interfering with the production of DNA.

Although these drugs have been used since the 1930s, researchers do not have a complete understanding of how a bacterium such as S. pseudintermedius can develop resistance to older sulfa drugs. In this project, WCVM veterinary microbiologist Dr. Joseph Rubin and CAHF research fellow Dr. Roshan Priyantha will investigate and characterize these mechanisms of resistance. Using whole genome sequencing, the team will compare the DNA sequences of drug-resistant and drug-susceptible bacteria to identify differences that result in resistance.

Results of their study will provide critical data to help diagnostic laboratories prolong the life of antimicrobial drugs and to choose the most effective treatments for dogs with these infections.

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