Flank spays
Question from Liza:
What are the advantages and disadvantages of the flank spay (in cats)?
Response from Julie Levy:
Great question Liza.
Let me start by saying that the benefits of one approach over the other are not so great that they exceed other issues, such as the comfort zone of the surgeon.
The flank approach places the incision on the flank of the cat about halfway down the side from the spine. The left side is more commonly used than the right, but it can be done on either side. The midline incision runs on the middle of the abdomen. The full uterus and ovaries can be removed from either approach. Out of tradition, the flank approach is taught in the UK, whereas the midline approach is taught in the US.
Benefits of the flank approach:
- It's a little faster (at least for me)
- An incisional complication will not lead to evisceration
- It is out of the way of mammary glands in lactating cats
- Caretakers can monitor the incision without handling the cat
- Good for cats with pyoderma of the ventral abdominal skin
Disadvantages of the flank approach are mainly due to the inability to perform a thorough exploratory of the abdomen.
- Harder to confirm that a cat has been previously spayed
- Nearly impossible to retrieve a dropped vessel, ovary, or uterus
- Unable to figure out those cats with weird anatomy that are missing parts of their reproductive tracts.
For feral cats, I prefer the flank approach. It's just a little easier for me. I don't like to spay juveniles this way because their tract is a little tighter and tears easier. It's harder to get the whole thing out via the flank in kittens. I also don't like to do pregnant cats via the flank, mostly because it leaves a large visible scar. However, I have ended up spaying both pregnant cats and cats with pyometra this way.
For pet cats, I prefer the midline approach. Sometimes hair on the incision line grows back kinky or another color or the scar is visible at the surgery site. There are no cosmetic problems with a midline approach. I don't think feral cats are as vain as pet cats.
Let me start by saying that the benefits of one approach over the other are not so great that they exceed other issues, such as the comfort zone of the surgeon.
The flank approach places the incision on the flank of the cat about halfway down the side from the spine. The left side is more commonly used than the right, but it can be done on either side. The midline incision runs on the middle of the abdomen. The full uterus and ovaries can be removed from either approach. Out of tradition, the flank approach is taught in the UK, whereas the midline approach is taught in the US.
Benefits of the flank approach:
- It's a little faster (at least for me)
- An incisional complication will not lead to evisceration
- It is out of the way of mammary glands in lactating cats
- Caretakers can monitor the incision without handling the cat
- Good for cats with pyoderma of the ventral abdominal skin
Disadvantages of the flank approach are mainly due to the inability to perform a thorough exploratory of the abdomen.
- Harder to confirm that a cat has been previously spayed
- Nearly impossible to retrieve a dropped vessel, ovary, or uterus
- Unable to figure out those cats with weird anatomy that are missing parts of their reproductive tracts.
For feral cats, I prefer the flank approach. It's just a little easier for me. I don't like to spay juveniles this way because their tract is a little tighter and tears easier. It's harder to get the whole thing out via the flank in kittens. I also don't like to do pregnant cats via the flank, mostly because it leaves a large visible scar. However, I have ended up spaying both pregnant cats and cats with pyometra this way.
For pet cats, I prefer the midline approach. Sometimes hair on the incision line grows back kinky or another color or the scar is visible at the surgery site. There are no cosmetic problems with a midline approach. I don't think feral cats are as vain as pet cats.
Response from Brenda Griffin:
Some surgeons prefer a flank approach rather than the traditional ventral midline incision. The flank approach allows caretakers to monitor a cat's incision from a distance and helps prevent evisceration should dehiscence of the surgical wound occur. The flank approach is not generally recommended for pregnant queens, but is desirable for lactating queens. I think Dr. Levy has covered this question very thoroughly, and I agree... as long as the surgeon is experienced, the cats should do well with either approach. I usually do the ventral mid-line approach myself.
Can you believe that Dr. Levy taught me to spay a cat when I was a senior student, which is when she was an intern (her first year out of vet school) at the MSPCA! Years later, I learned the flank approach at one her Operation Catnip clinics!
Can you believe that Dr. Levy taught me to spay a cat when I was a senior student, which is when she was an intern (her first year out of vet school) at the MSPCA! Years later, I learned the flank approach at one her Operation Catnip clinics!
Best anesthesia protocol
Question from Cathy:
Can each of you detail your anesthesia and other drug protocols for high-volume (50 or more) spay days? What kind/how do you give pain management drugs? What about drugs to wake the cats up faster after surgery? What is your reasoning for the particular protocol(s) you recommend? Have you made any changes to your protocols since inception of your programs, and why? Is there anything in particular you would NOT recommend or would warn against? Thank you.
Response from Julie Levy:
Our situation is pretty specialized. We only sterilize feral cats in large-scale clinics once a month.
The ideal anesthetic for us would be cheap, easy to administer to cats in their traps, allow a dosing scheme that does not require weighing the cats, have a rapid induction with minimal vomiting, provide predictable surgical anesthesia without the need for supplemental drugs, support the physiologic status of the cats, be rapidly reversible, provide potent and durable analgesia, and be completely safe for the cats and personnel. It would also be nice if the drugs were not controlled by the DEA.
Such an anesthetic has not yet been discovered, so we make lots of compromises. We use "TKX." To make this cocktail, take one vial of dry Telazol and add 4 ml of ketamine (100 mg/ml) and 1 ml of large animal xylazine (100 mg/ml). Regular adult cats receive 0.25 ml injected "intracat." Very large toms and advanced pregnant cats get 0.3 ml. Kittens get 0.1-0.15 ml. This is an off-label use of the drugs and no studies have been performed on the stability of the mixture. It costs about $1.70/cat.
TKX is very predictable with a low mortality rate (3.5 deaths/1000 cats). Cats are recumbent within 5 minutes of injection and usually remain in a surgical plane of anesthesia long enough to complete the surgery. We have isoflurane machines that are used to supplement cats by mask if they are too light for surgery. At the end of surgery, an equal amount of yohimbine is given IV to speed recovery. Some groups reduce the recovery time by cutting back on the TKX dose.
Although mortality is very low, we have also documented low blood pressure and low oxygen levels in more cats than we are comfortable with. We also have slow recoveries (partly due to hypothermia that develops), which forces us to release cats to their caretakers before they are fully recovered. I am certain that the analgesia provided by TKX, especially after reversal, is not optimal.
For these reasons, we are experimenting with other drug combinations to improve the safety and pain control of our anesthetic procedures. Currently, we are studying a cocktail of medetomidine, ketamine, buprenorphine. Stay tuned!
Here's an abstract of a paper we wrote about our experience with TKX.
J Am Vet Med Assoc. 2002 May 15;220(10):1491-5.
Use of the anesthetic combination of tiletamine, zolazepam, ketamine, and xylazine for neutering feral cats.
Williams LS, Levy JK, Robertson SA, Cistola AM, Centonze LA.
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610, USA.
OBJECTIVE: To evaluate the use of the anesthetic combination tiletamine, zolazepam, ketamine, and xylazine (TKX) for anesthesia of feral cats at large-scale neutering clinics.
DESIGN: Original study. ANIMALS: 7,502 feral cats.
PROCEDURE: Cats were trapped by their caretakers for a feral cat neutering program from July 1996 to August 2000. The anesthetic combination TKX was injected IM into cats while they remained in their traps. Each milliliter of TKX contained 50 mg of tiletamine, 50 mg of zolazepam, 80 mg of ketamine, and 20 mg of xylazine. Females were spayed by veterinarians, whereas males were castrated by veterinarians or veterinary students. Yohimbine (0.5 mg, IV) was administered at the end of the procedure. Logs were kept of the individual drug doses, signalment of the cats, and any complications encountered. These data were analyzed retrospectively (1996 to 1999) and prospectively (2000). RESULTS: Of the 5,766 cats for which dosing records were complete, 4,584 (79.5%) received a single dose of TKX. The mean initial dose of TKX was 0.24 +/- 0.04 ml/cat, and the total mean dose of TKX was 0.27 +/- 0.09 ml. Overall mortality rate was 0.35% (26/7,502) cats, and the death rate attributable solely to potential anesthetic deaths was 0.23% (17/7,502) cats.
CONCLUSIONS AND CLINICAL RELEVANCE: The use of TKX for large-scale feral cat neutering clinics has several benefits. The TKX combination is inexpensive, provides predictable results, can be administered quickly and easily in a small volume, and is associated with a low mortality rate in feral cats.
The ideal anesthetic for us would be cheap, easy to administer to cats in their traps, allow a dosing scheme that does not require weighing the cats, have a rapid induction with minimal vomiting, provide predictable surgical anesthesia without the need for supplemental drugs, support the physiologic status of the cats, be rapidly reversible, provide potent and durable analgesia, and be completely safe for the cats and personnel. It would also be nice if the drugs were not controlled by the DEA.
Such an anesthetic has not yet been discovered, so we make lots of compromises. We use "TKX." To make this cocktail, take one vial of dry Telazol and add 4 ml of ketamine (100 mg/ml) and 1 ml of large animal xylazine (100 mg/ml). Regular adult cats receive 0.25 ml injected "intracat." Very large toms and advanced pregnant cats get 0.3 ml. Kittens get 0.1-0.15 ml. This is an off-label use of the drugs and no studies have been performed on the stability of the mixture. It costs about $1.70/cat.
TKX is very predictable with a low mortality rate (3.5 deaths/1000 cats). Cats are recumbent within 5 minutes of injection and usually remain in a surgical plane of anesthesia long enough to complete the surgery. We have isoflurane machines that are used to supplement cats by mask if they are too light for surgery. At the end of surgery, an equal amount of yohimbine is given IV to speed recovery. Some groups reduce the recovery time by cutting back on the TKX dose.
Although mortality is very low, we have also documented low blood pressure and low oxygen levels in more cats than we are comfortable with. We also have slow recoveries (partly due to hypothermia that develops), which forces us to release cats to their caretakers before they are fully recovered. I am certain that the analgesia provided by TKX, especially after reversal, is not optimal.
For these reasons, we are experimenting with other drug combinations to improve the safety and pain control of our anesthetic procedures. Currently, we are studying a cocktail of medetomidine, ketamine, buprenorphine. Stay tuned!
Here's an abstract of a paper we wrote about our experience with TKX.
J Am Vet Med Assoc. 2002 May 15;220(10):1491-5.
Use of the anesthetic combination of tiletamine, zolazepam, ketamine, and xylazine for neutering feral cats.
Williams LS, Levy JK, Robertson SA, Cistola AM, Centonze LA.
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610, USA.
OBJECTIVE: To evaluate the use of the anesthetic combination tiletamine, zolazepam, ketamine, and xylazine (TKX) for anesthesia of feral cats at large-scale neutering clinics.
DESIGN: Original study. ANIMALS: 7,502 feral cats.
PROCEDURE: Cats were trapped by their caretakers for a feral cat neutering program from July 1996 to August 2000. The anesthetic combination TKX was injected IM into cats while they remained in their traps. Each milliliter of TKX contained 50 mg of tiletamine, 50 mg of zolazepam, 80 mg of ketamine, and 20 mg of xylazine. Females were spayed by veterinarians, whereas males were castrated by veterinarians or veterinary students. Yohimbine (0.5 mg, IV) was administered at the end of the procedure. Logs were kept of the individual drug doses, signalment of the cats, and any complications encountered. These data were analyzed retrospectively (1996 to 1999) and prospectively (2000). RESULTS: Of the 5,766 cats for which dosing records were complete, 4,584 (79.5%) received a single dose of TKX. The mean initial dose of TKX was 0.24 +/- 0.04 ml/cat, and the total mean dose of TKX was 0.27 +/- 0.09 ml. Overall mortality rate was 0.35% (26/7,502) cats, and the death rate attributable solely to potential anesthetic deaths was 0.23% (17/7,502) cats.
CONCLUSIONS AND CLINICAL RELEVANCE: The use of TKX for large-scale feral cat neutering clinics has several benefits. The TKX combination is inexpensive, provides predictable results, can be administered quickly and easily in a small volume, and is associated with a low mortality rate in feral cats.
Response from Brenda Griffin:
Dr. Levy's response and mine are virtually the same. We sterilize 60 - 100 cats in a morning and use TKX. We advise that cats be held in their traps overnight by their caretakers prior to release. Some cats do have more prolonged recoveries than others with this anesthetic cocktail.
TKX is prepared by reconstituting one vile of Telazol (500mg) with 4ml of Ketamine (100mg/ml) and 1ml Xylazine (100mg/ml). It should be noted that this is the concentration of Xylazine marketed for use in large animals and not the 20mg/ml small animal product. The dosage of TKX is 0.25ml per cat IM. A maximum dosage of 0.3ml per cat should not be exceeded. For very small kittens a slightly smaller dose of 0.15-0.2ml is used. This provides 20-30 minutes or more of anesthetic time. If additional time is required, an inhalent anesthetic such as Isoflurane should be used. Reversal (if needed) is achieved with Yohimbine (2mg/ml; 0.5ml per cat IM or IV). An additional dose of Yohimbine may be given after 30 minutes if results are inadequate.
Alternatively, a cocktail known as KDT) may be used. This is prepared by adding 10 ml vial of Ketamine (100 mg/ml), 1.0 ml medetomidine (Domitor, 1 mg/ml), and 3 ml butorphanol (Torbugesic, 10 mg/ml) to an empty 15 ml vial. Alternatively, the cocktail could be mixed in a 10 ml vial of Ketamine by first removing and discarding 1 ml of Ketamine to allow adequate space in the vial to add 0.9 ml medetomidine and 2.7 ml butorphanol. Dosage is 0.6 ml per average cat (slightly more for large cats and slightly less for small cats). Reversal is accomplished with antipamasol (Antisedan 5 mg/ml) at a dosage of 0.2 ml IM per cat. This does not buy you as much anesthetic time in my experience as TKX, and spays require supplemental isoflurane. Recovery time, however, is usually quicker. If I am working alone (not in the high volume clinic) doing a few cats myself, I use this.
Nothing is perfect, but we do the best we can to keep it safe, cost-effective, and balanced anesthesia, with good pain control.
TKX is prepared by reconstituting one vile of Telazol (500mg) with 4ml of Ketamine (100mg/ml) and 1ml Xylazine (100mg/ml). It should be noted that this is the concentration of Xylazine marketed for use in large animals and not the 20mg/ml small animal product. The dosage of TKX is 0.25ml per cat IM. A maximum dosage of 0.3ml per cat should not be exceeded. For very small kittens a slightly smaller dose of 0.15-0.2ml is used. This provides 20-30 minutes or more of anesthetic time. If additional time is required, an inhalent anesthetic such as Isoflurane should be used. Reversal (if needed) is achieved with Yohimbine (2mg/ml; 0.5ml per cat IM or IV). An additional dose of Yohimbine may be given after 30 minutes if results are inadequate.
Alternatively, a cocktail known as KDT) may be used. This is prepared by adding 10 ml vial of Ketamine (100 mg/ml), 1.0 ml medetomidine (Domitor, 1 mg/ml), and 3 ml butorphanol (Torbugesic, 10 mg/ml) to an empty 15 ml vial. Alternatively, the cocktail could be mixed in a 10 ml vial of Ketamine by first removing and discarding 1 ml of Ketamine to allow adequate space in the vial to add 0.9 ml medetomidine and 2.7 ml butorphanol. Dosage is 0.6 ml per average cat (slightly more for large cats and slightly less for small cats). Reversal is accomplished with antipamasol (Antisedan 5 mg/ml) at a dosage of 0.2 ml IM per cat. This does not buy you as much anesthetic time in my experience as TKX, and spays require supplemental isoflurane. Recovery time, however, is usually quicker. If I am working alone (not in the high volume clinic) doing a few cats myself, I use this.
Nothing is perfect, but we do the best we can to keep it safe, cost-effective, and balanced anesthesia, with good pain control.
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