Archived News

Clinical Study: Evaluation of Pain Reliever in Older Cats with Osteoarthritis

August 21, 2012

August 22, 2012

As part of his research into reducing pain in animals, Dr. Alonso Guedes, assistant clinical professor, is asking members of the public to help him conduct a free clinical study, “Analgesic evaluation of tramadol in osteoarthritic geriatric cats.”

Download the overview of this study (pdf)


The goal of this study is to evaluate whether tramadol, a painkiller, can produce pain relief in cats with osteoarthritis, a painful condition that affects up to 90% of senior cats.

What will happen in the study

Tramadol will be given orally at four different doses (0 mg/kg or placebo, 1 mg/kg, 2 mg/kg and 4 mg/kg) twice per day during five consecutive days/dose to 24 client-owned, senior cats (10 years old or older). Each cat will receive all doses in random order with a space of two days between each dose.

Owners will be unaware of the dose being given and will evaluate the pain relief on a weekly basis with the use of questionnaire designed specifically for their own cat. Cats will also wear an activity monitor device (e.g., a type of “pedometer”) on their neck to measure their activity level at home. These parameters will be compared using statistical methods.

Potential side effects

Tramadol may cause minor adverse effects such as sedation (cats appear sleepy), nausea, euphoria (increased friendliness) and itch. If any other adverse effects occur, the medication will be stopped immediately. There are very few options of drugs for pain relief to be used long-term in cats, and some have a high risk of causing severe adverse effects (i.e., stomach bleeding, liver and kidney damage). This study is an effort to increase the available options for pain relief in cats with osteoarthritis, which should directly impact their health and well-being.

Evaluation of potential candidates

1. Cats will be evaluated with general physical, orthopedic and neurological examinations, complete blood cell count and serum biochemical analyzes.

2. Orthogonal radiographs will be taken of joints suspected to have osteoarthritis based on history and physical examination.

Inclusion criteria

1. Only cats whose owners have noticed altered activity, with radiographic evidence of osteoarthritis and decreased muscle mass (for non-axial joints), with no detectable systemic disease and no clinically significant abnormalities on blood work will be included.

2. Cats must not be receiving any anti-inflammatory or other analgesic medications. Administration of glucosamine-chondroitin sulphate or similar medication (e.g., chondroprotectants) is acceptable as long as they have been administered for at least 10 weeks and their administration will not be changed during the study period.

3. Cats must be indoor-only, with owner-identified mobility impairment.

4. Owner must have a stable routine of daily living that is unlikely to change during the proposed study period (e.g., no impending changes such as moving house, vacations, introduction of new pets of people into the household).

5. Female cats must not be pregnant.

6. Owner participation is voluntary; written informed consent required prior to enrollment.

Criteria to discontinue treatment during the active phase of the study

1. Cats will be excluded if they miss more than one tramadol dose/week or if they develop important adverse effects (frequent nausea, vomiting, pruritus, seizures, serotonin syndrome, gastrointestinal bleeding or diarrhea, excessive sedation or dysphoria).

2. Cats will be excluded if any of the requirements listed above for inclusion in the study changed during the study or if they develop any other unanticipated adverse effect.

3. The study will be interrupted if adverse events become frequent and/or serious.

Please review the study criteria. If you or someone you know has a cat that may qualify for this study, please contact Dr. Alonso Guedes,
Please include “cat pain study” in the subject line of your message.

Thank you for helping the School of Veterinary Medicine improve the health and well-being of animals.