How to do pre-euthanasia sedation

From ANIMAL PEOPLE, December 2006:
Further to the discussion in your October article “Could
carbon monoxide gas chambers make a comeback,” I thought I’d wade in
on pre-euthanasia sedation.
There is often confusion of terminology. The word
“tranquilizer” and its verb form “tranq” are used generically. Same
with the word “sedation” and “sedate.”
Here’s what’s what:
Tranquilizer usually means phenothiazine-type drugs such as
acepromazine. Tranquilizers reduce alertness and increase tolerance.
They also reduce inhibition and blood pressure and lower the seizure
threshold in some species. Acepromazine is label approved for dogs,
cats and horses.

I do not recommend acepromazine as a pre-euthanasia drug due
to its generally poor effect. A dangerous dog or cat is still
conscious, therefore still dangerous. For friendly dogs, there is
no need to administer acepromazine, as there is no anxiety issue.
According to the one and only study on carbon dioxide
euthanasia, acepromazine is recommended for dogs being put to death
in carbon dioxide chambers. It was found to reduce anxiety response
in a significant percentage of dogs.
Sedatives reduce alertness by producing sleepiness. A
typical sedative is xylazine, also used as a short-term analgesic
and muscle relaxant. Brand names include “Rompun” and “AnaSed.”
These are label-approved for dogs and cats, at 20 mg/ml
concentration, and for horses, deer, and elk at 100 mg/ml
concentration. Adverse effects in dogs and cats include vomiting,
reduced blood pressure, and lowered inhibition.
I do not recommend xylazine as a pre-euthanasia drug due to
its generally poor effect. A dangerous dog or cat is still
dangerous, even if sleepy and muscle relaxed, and the reduction in
blood pressure is significant, a problem when trying to inject
intravenously. For friendly dogs, there is no need to
administer xylazine as there is no anxiety issue.
Anesthesia means loss of sensation, usually loss of
consciousness brought about by the administration of an anesthetic.
To be anesthetized literally means to have no feeling.
The best pre-euthanasia drugs are anesthetics. Most common
and cost-effective is PreMix (5:1 ketamine-xylazine), dosed at
0.5-0.6 ml per ten pounds. An anesthetized dog or cat is
unconscious, and therefore safe to handle. Adverse effects can be
seizures or vomiting. PreMix is a veterinary compound in use since
the mid-1970s, and is not an FDA approved drug.
Another pre-euthanasia anesthetic is Telazol
(tiletamine-zolazepam), an FDA-approved drug similar in action to
PreMix. Telazol is label-approved for dogs and cats and is, like
PreMix, an effective pre-euthanasia drug when dosed at 0.3-0.6 ml
per ten pounds.
There is a fallacy that best practice is to anesthetize all
animals prior to euthanasia. This is simply not so. Best practice
is to administer pre-euthanasia anesthetics when safety or technical
difficulty issues arise. An intramuscular injection of a stinging
medicine, such as either PreMix or Telazol, is in my
opinion counterproductive unless needed.
The use of IV catheters for guardian-present euthanasia is
becoming more prevalent in animal shelters, as well as in private
veterinary practice. I mention their use in my
euthanasia-by-injection classes.
I have been euthanizing feral cats for years, and believe
that PreMix or Telazol first is the way to go. Then, when they are
deep enough that they have a negative pinch-withdraw reflex, I
administer the sodium pentobarbital via intracardiac injection,
except for pregnant cats. Then I go IV.
I have also euthanized friendly cats, more than I can count
unfortunately, and am a total fan of intraperitoneal. They never
stop purring through the entire process, only stopping when they
lose consciousness.
–Doug Fakkema
Animal Care &
Control Consultant
18 Hillcreek Blvd
Charleston, SC 29412
<Dkfakkema@aol.com>
More about pre-euthanasia sedation of cats

For euthanasia pre-sedation, we use telazol, which combines
tiletamine hydrochloride 50 mg/mL, and zolazepam hydrochloride 50.
Tiletamine is similar to ketamine, and zolazepam is similar to
diazepam (Valium). The tiletamine stings a bit, the only downside.
Tiletamine and ketamine are dissociative anesthetics, but don’t
relax muscles. The zolazepam produces comfortable muscle relaxation
and, with the tiletamine, combines to produce moderate anesthesia
and very significant sedation.
The reason we like this combination is that, unlike with
xylazine, the blood pressure doesn’t plummet. Low blood pressure
makes finding a vein very tough sometimes.
I also find that with telazol, I see much less twitching,
and less agonal breathing in cats. The twitching and gasping breaths
are spinal reflexes, and don’t represent pain, but sure are
disconcerting for the humans. In five years, I have seen two cats
become twitchy or agitated with telazol. One was actually a serval,
so who knows? The other was a very ill cat. The excitement lasted
only a few seconds.
Considering how many euthanasias we do, it is hard to
imagine a lower rate of complication. Technical information about
telazol can be verified at <www.vasg.org>. This is a very good site
on animal anesthesia, and I use it all the time.
Telezol is much better for cats than dogs. I wouldn’t use it
with dogs, based on what others have told me.
Some people insist that the only way to euthanize is with an
IV catheter in place. We find that the telazol produces comfortable
sedation and such good anesthesia that cats never notice the second
IV injection. To put in a catheter requires restraint, and while
catheters are usually not painful, that is not always true. The
telazol/euthanasia solution combination allows people to be with
their cat for the entire process, and fussing with the catheter is
avoided.
I was aghast to learn how executions by lethal injection are
carried out. Apparently they use a paralytic agent, so if the
condemned person is under-sedated, the person could be conscious for
what is essentially a heart attack, chemically-induced with
potassium chloride, or suffocation, because of inability to
breathe. Also, the IV catheters used for human executions are not
put in by experts, and the drugs can easily precipitate if they are
accidently mixed. We do better, much better for our dogs and cats.
–Katherine Schubert, DVM
Cats Exclusive
Veterinary Center
19203 Aurora Ave. N.
Shoreline, WA 98133
1-206-546-CATS
<www.catsexclusive.com>