Study Seeks to Make Vaccination Safer for Cats

by Cleon Hendricks

November 27, 2012

Cat receiving vaccine in tail
HSVMA member and veterinary student, Cleon Hendricks, participated in a study that looked at the effectiveness of administering vaccines to cats in alternate sites, such as the tail.
Cleon Hendricks

Feline injection site sarcoma (FISS) is an unfortunate consequence of vaccination affecting 1 to 10 cats per every 10,000 cats vaccinated. Over the past 20 years, radical surgery has been shown to lead to the best outcomes. Although lifesaving, such surgery is expensive, disfiguring, and can impact the welfare of a patient. The purpose of this pilot study was to assess an alternative to currently recommended vaccination sites in terms of preference by oncologists, ease of injection, and serological responses.

A new approach

At 1:52 a.m. on February 9, 2012, I received the email that granted me the opportunity to work on this pilot study and add to this 20-year knowledge base of FISS research. After a “Congratulations!” I was presented with survey data from numerous oncologists polled for their opinions of alternative vaccination sites with radical surgical treatment of injection site sarcomas in mind. After processing the responses, it was apparent that a large number of oncologists preferred the tail as an alternative to traditional sites, and with such an interest in a novel site I quickly realized the potential impact that this pilot study could have on the treatment and management of FISS. Naturally, I was excited about the opportunity to be involved in a landmark project from the ground up- working on a hypothesis as well as the methods and procedures needed to conduct the study with my advisor, Dr. Julie Levy.

The first hurdle was to determine if cats would even allow vaccination in their tails. Cats admitted to the local trap-neuter-return program were divided into two groups: One group received both FVRCP and rabies vaccines subcutaneously in the distal tail, and the other group received the same two vaccines subcutaneously in the distal hind limbs. A numerical scale was used to measure that cats’ reaction to vaccination in either site. At this point, I was a bit fearful as to how cooperative my community cat patients would be. For several weeks leading up to our trial run, I pictured cats flying off of the tables in fear, climbing the walls, and leaving their autographs on our skin as we attempted to gather data. The reactions I got from other doctors and peers as I explained my project also did not help with my anxiety. However, to the surprise of Dr. Levy and myself, the first trial in April went smoothly and I was sent home with a log book, an inch thick binder full of data, and a spreadsheet that was sure to fill any computer screen I sat in front of for the next four months. By the end of the study, we found that cats accept vaccination in the tail just as well as they do in the leg.

To determine if cats respond to vaccination in the tail as well as vaccination in traditional sites, serum was collected before vaccination and one-to-two months afterwards. We instructed clients to bring in the cats at a specific date, but in some instances I had to go out, set traps, scan the cats (microchips were implanted to ID our cats), bring them back to the vet school, and then release them back to the area they called home. Antibody titers against panleukopenia virus (FPV) and rabies virus (RV) were determined. With the successes we had encountered thus far and the last objective of our study still to be met, I was afraid of undesirable titer results marking the end of our study. However, I stayed positive, relying on the knowledge that I learned as a freshman in immunology class and the pop quizzes given by Dr. Cynda Crawford, an immunologist also involved in the study. My fears subsided as the titer results reported a positive serological response for all of my patients vaccinated in the distal tail for feline panleukopenia. For the cats vaccinated in the tail for rabies, adequate antibodies titers developed in all but one cat. Thus, we were able to prove that the serologic response to vaccination in the tail was as effective as vaccination in the distal hind limb.

With all three objectives of the pilot study met, we were able to show that tail vaccination was well-tolerated and elicited similar serological response to vaccination in the distal limbs.

The experience

Cleon Hendricks and cat
Participating in this study changed Hendricks' perspective about free-roaming cats and their effect on a community.
Cleon Hendricks

Before moving to Gainesville, Fla. from West Palm Beach, I was unfamiliar with the community cat issue that exists in many areas of the country. In South Florida, there is minimal effort to disseminate public education about community cats, nor are there adequate proactive and humane solutions in place such as the trap-neuter-release (TNR) programs that exist in Gainesville. The result is thousands of cats entering animal shelters and waiting for their chance of adoption. Living in Gainesville has opened my eyes to the topic, as well as the polarizing debates that surround the issue. After working on my project, I discovered that a perceived problem can create a new frontier in the welfare of cats undergoing routine medical procedures. Also, I now feel that community cats should not be looked at as a nuisance or a harbinger of extinction to wildlife, but could serve as a teaching resource for veterinary students and researchers alike, from learning routine surgical procedures to studying feline population dynamics. I was proud that the cats in my study also benefited by receiving sterilization surgery before rejoining their friends back in the colonies they called home.

Cleon Hendricks

Cleon Hendricks is a student at the University of Florida College of Veterinary Medicine, class of 2015, and an HSVMA member.