Benzocaine

[sarah]

I have a very, very ill newt that I decided I would anesthetize and then euthanize as he could not even regulate the air he was "eating" and was floating with use only of three legs... (He obtained a fungal infection some time ago but fell into a remission now 5 months later when he got a minor cut, which worked its way up to a large lesion in addition to other fungal sites which did not respond to other treatments). I tried the ventral application of a 20% benzocaine product which would allegedly put the animal down in under a minute. I was very upset as this was my "baby" if you will, and I returned from a bout of crying to find he was in a different position. This was even more disturbing. I tried additional applications fo the benzocaine and even fifteen minutes later he was still moving! This was extremely traumatic, and he is still yawning and stuff right now. I placed him back in the quarantine tank, as it seems it has only anesthetized him. He is there as we speak. I am VERY upset! The information listed on Caudate Central noted that this was a quick and effective method of euthanization and my poor little guy still has not passed! If you have a terminally ill newt, do NOT use this method! (My newt is a 6 inch Cynops pyrroghaster).

 

[sarah]

In browsing this morning, I just found that I have been calling my newt the wrong thing...and this would explain why I have not seen a similar newt since. It is a Paramesotriton hongkongensis. He is so beautiful...and BTW still swimming around in the tank, although I believe the Benzocain did numb the site of his wound as he is swimming around much happier than before. If anything, perhaps I will continue lower-amount applications of the benzocaine directly on the site of injury, and this way he will at least have an easier journey as he passes.

 

[edward]

Hi Sarah,
Here is the exerpt from the article you are referring to on euthanasia (below my response).
As was pointed out in the article the use of benzocaine products has not been accepted as an approved method for euthanasia. In all of the cases that I am aware of so far benzocaine has only been used in relatively thin skinned amphibians (like plethodontids). Benzocaine has not been used in thicker skinned amphibians such as paramesotritions, or tylototrition. It is possible that in these animals the skin is relativley impermeable to such products and either is less effective or takes a significantly longer time frame to begin to work. Also the caudates referenced in article are significantly lower in body weight that the newt you mentioned in your post. If the animal is in bad enough condition that your believe it should be euthanized then I would recommend taking the newt to your local vet for one of the recognized methods of euthanasia.
Additionally I would not recommend "treating" the newts pain with additional treatments of benzocaine as benzocaine may be damaging to the animals kidneys and/or liver.
Ed

Benzocaine. Orajel® (and other painkillers containing benzocaine) appear to rapidly anesthetize and euthanize amphibians. This method has not yet been accepted by the National Research Council on Pain and Distress in Laboratory Animals, probably due to how recently the publications involving these products have come out. Products containing either 7.5% or 20% benzocaine have been shown to be effective in the euthanasia of amphibians. The original descriptions of this procedure had the gel containing the benzocaine applied to the head of the amphibian, however it has been shown that it may be more effective if applied to the ventral (belly) surface of the animal (this may actually be most effective in anurans, which have pelvic patches, rather than caudates). A 5-mm drop applied to the ventral surface of a Eurycea quadridigitata resulted in relaxation and death in less than one minute (Chen and Combs, 1999).

 

[Jennewt]

Sarah, that is distressing. Do you put the animal back in the water after applying the benzocaine? Maybe it rinses off.

If you still decided you need to euthanize, and can't afford a vet, I'd suggest 5% ethyl alcohol. You can buy 70% or 95% ethyl alcohol at any full-service pharmacy (not the grocery store pharmacies, they usually carry only isopropyl). Dilute it down to 5% and put a shallow layer in a plastic shoebox. When I used it, the newt (a small eastern) was non-responsive within 10 minutes. Once it is non-responsive, you can add in some of the 70/95%.

 

[sarah]

Update: My newt passed away sometime yesterday as a result of illness. He was fighting so hard...

BUT, I did want to recommend the species to anyone with a basement. When kept at temperatures around 65 degrees, he was completely problem free and I assume temperature was the source of the fungal infection problem, although there was little else I could do to keep the temperature down than the "ice tricks" and such. If you're looking for a hardy newt though, try and find a P. hongkongensis. I didn't realize how rare they are in the US as the pet store sold it to me (idiots) as a C. pyrroghaster, but it was a good eater and a wonderful pet for two years. If I find another one (and several hundred dollars for some sort of refrigeration unit) then I will most certainly care for as many as I can house!