Pain management in companion animals is likely to get a boost upon completion of two studies set to begin at Kansas State University College of Veterinary Medicine, while some finished research will help veterinary clinics and owners minimize dogs’ pain after surgery and may help with human patients as well.
James K. Roush, D.V.M., M.S., an ACVS diplomat andKSU professor of clinical sciences, undertook a study on the application of hot and cold packs, he says, because doctors tell people how long to apply them, but no one had looked at the practice scientifically to see how far the cold or heat penetrates tissue or how long each needs to be applied for the tissue to be cold or warm enough to reduce inflammation.
So, the study, done with Ralph Millard, D.V.M. a former KSU Veterinary Health Center resident, did just that. Using 10 sedated, medium-sized dogs that were already part of another study at the veterinary school, electrodes the size of a 22-gauge needle were inserted through a hole in the center of a specially designed cold or hot pack into the dogs’ tissue.
The researchers discovered that cold packing “actually has effects for a long time,” about 80 minutes or so, says Roush, a veterinary orthopedic surgeon who specializes in small animal surgery and canine osteoarthritis. However, “The hot packing comes back to a normal temperature almost immediately.” Both create the desired temperature within 10 minutes of being applied, and applying either for a longer period doesn’t significantly increase or decrease the tissue temperature.
The purpose of putting cold on an area is to decrease blood flow, Roush explains, while a heat pack helps return blood flow to normal. The combination is often used on closed incisions and other areas of inflammation.
Stressing that more research is needed, Roush says there is a “strong possibility” that a similar 10-minute time frame may apply to humans too.
‘Force Mat’ Assists Osteoarthritis Study
In about a month, Roush says, he and Matt Sherwood, a veterinary resident, will be using something called a “force mat” to measure how effective various treatments for osteoarthritis are in restoring a dog’s use of an affected limb. Right now, they’re reviewing a couple of human studies that used force mats to measure people’s recovery. The mat essentially measures the pressure of each limb as the subject stands or walks across it, Roush explains.
In the past, force plates were used for the same purpose. However, a plate requires that it be struck “exactly correctly” for the measurements to be accurate, Roush says. The force mat is more forgiving, so the testing goes much more quickly.
The KSU study will be the first using a force mat to quantify improvements after treatment for osteoarthritis, he says.
The protocol developed during the study will also allow the use of such mats for evaluation of canine and feline lameness of any kind. In animals with osteoarthritis, the mat pressure measurements will reveal which leg is most affected by the disease.
The mat will immediately be of assistance to patients of the Veterinary Health Center. “We can measure their recovery and a variety of other aspects: how they respond to nonsteroidal anti-inflammatories, how they respond to narcotics or how they respond to a surgical procedure that is designed to take that pressure off the joint,” Roush says.
Looking at the Next Big Pain Medication?
Two of Roush’s colleagues, plus resident Marian Benitez, will join forces with him to study the potential of hydrocodone as a pain medication in dogs.
Some veterinary surgeons already use the drug, but “how well it works has not been well-established in dogs,” Roush says. “The gold standard in post-operative pain has been tramadol, but the more we learn about it, the more we see that it’s a poor analgesic in dogs.
“It works really well in people. The pharmacokinetics are quite different in dogs,” he says, pointing out that the human dose is 1 mg per kilogram of weight at the low end. For dogs, it takes up to 9 mg per kilo to have the desired effect. “There are lots of side effects at that dose, so we’re looking for an alternative.” A previous study showed that 0.5 mg/k of hydrocdone did a “decent” job, he says, and lasted about six hours. “The question is what would multiple dosing do and how good an analgesic is it,” he says.
During his career, Roush has been awarded nearly $500,000 in research grant funds. He has published more than 90 journal articles and book chapters.
“I’ve been a pretty eclectic researcher over the years,” he says. His interest in pain management research is at least three-fold, he says. First, because he’s an orthopedic surgeon, he wants to be able to ease the pain of his post-operative patients as efficiently as possible. Second, such research is not very invasive to dogs so it raises fewer ethical concerns and barriers. Third is that smaller projects can be accomplished during a resident’s time at the veterinary school. “Short, discrete projects are quick and easy to fund, and I’ve got bodies to do them,” he says.
That might be the case, but they still can easily lead to better pain treatment for our dogs in the future.
This article was prepared using materials provided by Kansas State University, along with a supplemental telephone interview with James Roush.