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I am thinking about updating our feral cat spay/neuter protocol. Currently, the cats are brought in the night before or (preferably), the morning of, induced with butorphanol/ketamine/dexdomitor IM, tested for FeLV/FIV, placed on gas anesthesia (mask with iso), neutered, left ear tipped, given SQ fluids (100mls 0.9% NaCl), given vaccines (rabies, FVRCP, FeLV), then reversed with antiseden IM. The cats are then sent home the next morning. I have had very few problems with this protocol (approximately 1-2 cats/month in the last six months but I am seeing more people utilizing this service in the last month). Lately, I have been reading more about using Telazol as an induction agent. It is not an agent I am real familiar with using. However, I don't want to ignore a potentially useful option if it would be beneficial for the patients I see. What are the shelter program's current recommendations for standard of care for feral cats? Thank you.
Thank you for your question and for continuing to think about how you could improve the welfare and care of feral cats. We hope to provide you with some helpful information to allow you to make informed decisions about what protocols will work best in your clinic.
At feral cat clinics, Telazol (equal parts tiletemine and zolazepam) is frequently combined with ketamine and xylazine to form an intramuscular anesthetic mixture that provides good sedation and analgesia for the purposes of spay/neuter surgeries. This mixture has been selected because tiletemine and ketamine are dissociatives that provide analgesia, immobilization and general anesthesia; zolazepam is a benzodiazepine with anxiolytic and muscle relaxant properties; and xylazine is a mixed alpha 1 and alpha 2 adrenergic receptor agonist that provides short duration analgesia, sedation and muscle relaxation.
Some of the advantages that veterinarians have found in using Telazol, in this TKX combination, are that a smaller volume is needed compared to other mixes, there is rapid onset (3-4 minutes to recumbency), this combination is partially reversible with yohimbine (IV) and it tends to be more cost effective than your current protocol. The disadvantages are that it tends to lead to a slower recovery than your current protocol and there is an increased risk of hypothermia due to the drug itself and the prolonged recovery and that it may not provide adequate analgesia in all patients (Cistola, Golder et al. 2004) . Also, as with most anesthetic agents, there is a risk of hypotension and hypoxemia. In our experience, most cats (~80%) can be maintained under this anesthesia for the duration of their surgery and do not need the addition of gas anesthesia. If a TKX mix is used, many times buprenorphine is given during recovery for additional analgesia. (Cistola, Golder et al. 2004)
Some useful tips to help with hypothermia that we picked up over the years are using warmed scrub/rinse solutions (in a crockpot or baby bottle warmers), avoiding alcohol rinse, keeping the cats on a blanket or towel at all times, shaving hair conservatively and using warm water pads or some other external heat support throughout surgery and recovery until temp is 98F.
Humane Alliance, the leader in HQHVSN, uses a different Telazol protocol. They use Telazol mixed with diluted ace and buprenorphine as their anesthesia protocol in cats. They would be a wonderful resource for you to contact to learn more about their use of Telazol and how they feel their protocol works in feral cats - http://humanealliance.org/
The current anesthetic protocol (DKT) that you are using is commonly used and is acceptable as well. The advantages of DKT are that it is more reversible and does tend to offer greater cardiovascular support. The disadvantages are that a larger volume is needed, veterinarians have seen more post injection apnea, it tends to be more expensive and to some degree, clinics have experienced hyperthermia and hyper-excited recoveries.
Another consideration in your current protocol is testing for FIV/FeLV. Testing for these viruses in feral cats has been a topic of much consideration and debate in recent years. Studies have shown that the prevalence of FIV/FeLV among feral cats is comparable to pet cats and that they do not pose a greater risk to other cats (Lee, Levy et al. 2002; Luria, Levy et al. 2004; Levy, Scott et al. 2006). Neutering reduces the most common sources of infection for both of these viruses – partition and fighting among males. Because of these findings, most large TNR programs no longer test for retroviruses. With that said, they also do not vaccinate for FeLV. The cost savings of not providing testing and vaccines will in turn allow you to do more surgeries and thus ultimately provide better control of these retroviruses.
Lastly there are a few critical aspects of successful TNR clinics that we have learned and that we like to share. Always keep cats covered when they are awake (pre and post op) in their traps. This is the best method to limit stress and hopefully decrease the risk of illness. Also, close monitoring from induction to recovery is the number one tool to limit anesthetic complications and death.
We hope that this information has been helpful and that you continue to have success with your feral cat TNR program!
Cynthia Karsten, DVM
Resident, Koret Shelter Medicine Program
Center for Companion Animal Health
UC Davis School of Veterinary Medicine