Free
Correspondence  |   July 2009
Chloral Hydrate Is Not Acceptable for Anesthesia or Euthanasia of Small Animals
Author Affiliations & Notes
  • Bu-Wei Yu, M.D., Ph.D.
    *
  • *Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People's Republic of China.
Article Information
Correspondence
Correspondence   |   July 2009
Chloral Hydrate Is Not Acceptable for Anesthesia or Euthanasia of Small Animals
Anesthesiology 7 2009, Vol.111, 209-210. doi:10.1097/ALN.0b013e3181a98c58
Anesthesiology 7 2009, Vol.111, 209-210. doi:10.1097/ALN.0b013e3181a98c58
In Reply:—
We sincerely thank Baxter et al  . for their interests in our article and their valuable information about the use of chloral hydrate for rats' anesthesia and euthanasia in our experiment.
First, we would like to emphasize that we do not think the reliability of our experimental results was influenced by chloral hydrate. Chloral hydrate was used in all the experimental groups, thus its interpretations were comparable among these groups. Our significant findings could not be simply induced by it. In addition, the mechanisms of most anesthetics, including their effects on Arc expression, are still obscure. Furthermore, sevoflurane has even been proved to inhibit Arc transcription.1 Under this condition, choosing any other anesthetic for rat euthanasia may produce the similar unpredicted interpretations. Therefore, we believe that to a great extent, our results and conclusions are reliable.
Second, we designed our experiment on the basis of a great deal of published articles on authority journals. The method as intraperitoneal injection of chloral hydrate was wildly used to rats for some kinds of surgeries, particularly with the word as “anesthesia.” For example, Rodríguez Manzanares et al  ., Bredeloux et al  ., and Sammut et al  . all use chloral hydrate to anesthetize rats for stereotaxic neurosurgery to implant cannulae.2–4 Actually, in recent years, chloral hydrate is still widely used to anesthetize rats. However, we agree with the view of Baxter et al  . that some other anesthetics (like Phenobarbital sodium) may be more suitable in this type of surgery because of the side effects of chloral hydrate illustrated by them. Fortunately, the overwhelming majority of rats in our experiment recovered well from the neurosurgery, with normal appetite and defecation.
Third, we admit that we neglect the potential problem of using chloral hydrate for euthanasia of rats. Chloral hydrate is a traditional anesthetic in animal experiments, and before we performed our study we also found that it is used for killing rats by either decapitation or cardiac perfusion in respectable published articles.2,5,6 Moreover, our research was approved by the Institutional Animal Care and Use Committee with no questions. Therefore, we never doubted the use of chloral hydrate for rat euthanasia. Now we feel deeply sorry for the possibility of inflicting pain on the animals because of using chloral hydrate.
Finally, we would like to extend our sincere gratitude to Baxter et al  . for letting us understand animal euthanasia more deeply. We will pay much more attention to the euthanasia issue, adopt proper and scientific animal welfare methods, and try our best to decrease harm to the experimental animals as much as possible in future research.
*Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People's Republic of China.
References
Kobayashi K, Takemori K, Sakamoto A: Circadian gene expression is suppressed during sevoflurane anesthesia and the suppression persists after awakening. Brain Res 2007; 1185:1–7Kobayashi, K Takemori, K Sakamoto, A
Rodríguez Manzanares PA, Isoardi NA, Carrer HF, Molina VA: Previous stress facilitates fear memory, attenuates GABAergic inhibition, and increases synaptic plasticity in the rat basolateral amygdala. J Neurosci 2005; 25:8725–34Rodríguez Manzanares, PA Isoardi, NA Carrer, HF Molina, VA
Bredeloux P, Dubuc I, Costentin J: Comparisons between bupropion and dexamphetamine in a range of in vivo  tests exploring dopaminergic transmission. Br J Pharmacol 2007; 150:711–9Bredeloux, P Dubuc, I Costentin, J
Sammut S, Dec A, Mitchell D, Linardakis J, Ortiguela M, West AR: Phasic dopaminergic transmission increases NO efflux in the rat dorsal striatum via  a neuronal NOS and a dopamine D(1/5) receptor-dependent mechanism. Neuropsychopharmacology 2006; 31:493–505Sammut, S Dec, A Mitchell, D Linardakis, J Ortiguela, M West, AR
Reiner K, Sukhotinsky I, Devor M: Mesopontine tegmental anesthesia area projects independently to the rostromedial medulla and to the spinal cord. Neuroscience 2007; 146:1355–70Reiner, K Sukhotinsky, I Devor, M
Martínez-Peña y Valenzuela I, Carmona-Calero EM, Pérez-González H, Ormazabal-Ramos C, Fernández-Rodríguez P, González-Marrero I, Castañeyra-Perdomo A, Ferres-Torres R: Alterations of the cerebrospinal fluid proteins and subcommissural organ secretion in the arterial hypertension and ventricular dilatation. A study in SHR rats. Histol Histopathol 2006; 21:179–85Martínez-Peña y Valenzuela, I Carmona-Calero, EM Pérez-González, H Ormazabal-Ramos, C Fernández-Rodríguez, P González-Marrero, I Castañeyra-Perdomo, A Ferres-Torres, R