Strategic Objectives


KE Joubert MMedVet (Anaes), BVSc Anaesthesiology: Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, U. P.

Private Bag X04, Onderstepoort, 0110, RSA, (012) 529 8137 (Office), (012) 529 8307 (Fax), This email address is being protected from spambots. You need JavaScript enabled to view it.


The intention of this document is to review the various options available for chemical restrain vicious dogs. It is important to realise from the outset that your safety is of particular importance. When administering drugs to aggressive patients, care should be taken to prevent the dog from attacking you. More importantly however it should be ensured that the dog does not attack the owner. This consequence may have legal implications for the veterinarian. Intramuscular drugs are preferably administered by a poll syringe from a distance or a dart gun may be used. If dogs can be restrained manually, intravenous access may be readily obtained and drugs may be administered intravenously.

My technique for aggressive dogs that can be manually restrained is to obtain intravenous access in either the cephalic or the saphenus vein. This is followed by the intravenous administration of thiopentone in healthy dogs, endotracheal intubation and the administration of halothane. This option is usually only available in dogs that have been well trained.


Many veterinarians use acetylpromazine to sedate aggressive dogs. Very often tablets are given to owners to administer to the dog at home before bringing it to the consulting room. Although this has been successful in many cases this practice is ill-advised. Acetylpromazine is a tranquilliser and as such has a ceiling sedative effect. Clinically this means that sedation increases to a point beyond which no increase is clinically seen. Acetylpromazine is also an anxiolytic. Anxious dogs may be prevented from biting by the administration of acetylpromazine. Increasing doses of acetylpromazine cause the dog to become collapsed due to hypotension. Any increase in adrenergic tone will briefly reverse the hypotension giving the dog enough strength to bite someone. But more importantly, acetylpromazine may make aggressive dogs even more aggressive by the removal of fear. There are reports in the literature of this effect and hence acetylpromazine should be avoided in aggressive animals. If a veterinarian were to prescribe acetylpromazine to an aggressive dog and the dog was to bite the owner then there may very well be legal ramifications as this effect has been documented.

The sedative effects of acetylpromazine can be increased by combining acetylpromazine with opioids (a neurolept combination). Appropriate opioids that can be used include morphine, fentanyl and buprenorphine. Buprenorphine takes approximately 30 minutes to reach its peak effect and hence should be given in advance. After the administration of a neurolept combination the animals should be allowed to quietly rest until the drugs have exerted full effect. Neuroleptic combinations may even be administered intramuscularly or intravenously.

Alpha2 Agonists

The alpha2 agonists are potent sedatives in small animals. The alpha2 agonists are known to cause cardiovascular disturbances. The cardiovascular disturbances include an initial hypertension followed by slowing of the heart rate (bradycardia), SA and AV blocks, and a reduction in cardiac output. These cardiovascular changes may be detrimental in a compromised patient. Respiratory depression is also evident after the administration of these drugs. The intramuscular administration of the alpha2 agonists will usually result in good sedation. That is provided the animal is allowed to relax in a stress free environment after the administration of the alpha2 agonist. Failure to do this resulted inadequate sedation. Some dogs may still respond to painful stimuli and stress with an aggressive reaction after the administration of an alpha2 agonist alone. The sedative action of alpha2 agonist can be increased by the administration of an opioid, similar to that of the neuroleptic combination. If anaesthesia is to be induced after the administration of an alpha2 agonist the dose of the anaesthetic agent should be carefully titrated to effect to avoid an accidental overdose. All the alpha2 agonists are reversible bringing an element of safety.

As an alternative, alpha2 agonists can be administered with ketamine intramuscularly to induce anesthesia. Such a combination can be administered through a pole syringe. An additional dose of thiopentone or propofol may be required for the endotracheal intubation.

Alpha2 agonists may also be administered orally. The drug should be administered preferably sublingually as rapid absorption takes place. The dose of alpha2 agonist needs to be increased by two to fourfold for an optimal effect. Again the patient needs to be left in a quiet stress free environment for approximately 30 minutes before it is handled.

Alpha2 agonists have been successfully used subcutaneously in animals. The subcutaneous administration may be more easily accomplished. Again sufficient time must be allowed for the drug to take effect before the animal is handled.


This is another useful combination for aggressive dogs. The drug may be administered intramuscularly to produce profound sedation or anaesthesia for 30 – 60 minutes. The drug combination may also be administered orally to animals in a small quantity of food or sprayed into the mouth. The patient should then be allowed to become sedated in a quiet stress free environment. The cardiovascular stability of this drug combination is good.


Pentobarbitone can be administered orally to animals. The dose required is quite large, between 40 and 80 mg/kg. The time for this drug to achieve its full effect may be well over an hour.



Dose Rate


0.01 – 0.5 mg/kg


0.01 – 0.03 mg/kg


10 – 30 mg/kg


0.01 – 0.1 mg/kg


0.1 – 1 mg/kg


10 – 80 mg/kg


0.5 – 1 mg/kg


0.5 – 1 mg/kg

Table 1: Drugs Dose rates. The following are suggested drug dose rates. Routes of administration and the clinical condition need to be considered when administering these agents. 1.


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8. Hatch, R. C., Clark, J. D., Booth, N. H. and Kitzman, J. V. 1983 Comparison of five preanesthetic medicaments in pentobarbital-anesthetized dogs: antagonism by 4-aminopyridine, yohimbine, and naloxone. American Journal of Veterinary Research 44: 12: 2312 - 2319.

9. Hellyer, P., Muir, W. W., Hubbell, J. A. E. and Sally, J. 1988 Cardiorespiratory effects of the intravenous administration of tiletamine - zolazepam to cats. Veterinary Surgery 17: 2: 105 - 110.

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11. Klide, A. M., Calderwood, H. W. and Soma, L. R. 1975 Cardiopulmonary effects of xylazine in dogs. American Journal of Veterinary Research 36: 7: 931 - 935.

12. Ko, J. C. H., Bailey, J. E., Pablo, L. S. and Heaton-Jones, T. G. 1996 Comparison of sedative and cardiorespiratory effects of medetomidine and medetomidine-butorphanol combination in dogs. American Journal of Veterinary Research 57: 4: 535 - 540.

13. Ko, J. C. H., Fox, S. M. and Mandsager, R. E. 2000 Sedative and cardiorespiratory effects of medetomidine, medetomidne-butorphanol, and medetomidine-ketamine in dogs. Journal of the American Veterinary Medical Association 216: 10: 1578 - 1583.

14. Lamont, L. A., Bulmer, B. J., Grimm, K. A., Tranquilli, W. J. and Sisson, D. D. 2001 Cardiopulmonary evaluation of the use of medetomidine hydrochloride in cats. American Journal of Veterinary Research 62: 11: 1745 - 1749.

15. Meyer, E. K. 1997 Rare idiosyncratic reaction to acepromazine in dogs. Journal of the American Veterinary Medical Association 210: 8: 1114 - 1115.

16. Moens, Y. and Fargetton, X. 1990 A comparative studt of medetomidine/ketamine and xylazine/ketamine in dogs. Veterinary Record 127: 567 - 571.

17. Raiha, M. P., Raiha, J. and Short, C. E. 1989 A comparison of xylazine, acepromazine, meperidine and medetomidine as preanesthetics to halothane anesthesia in dogs. Acta Veterinaria Scandanavia 85: 97 - 102.

18. Ramsay, E. C. and Wetzel, R. W. 1998 Comparison of five regimens for oral administration of medication to induce sedation in dogs prior to euthanasia. Journal of the American Veterinary Medical Association 213: 2: 240 - 242.

19. Robertson, S. A., Hauptman, J. G., Nachreiner, R. F. and Richter, M. A. 2001 Effects of acetylpromazine or morphine on urine production in halothane-anesthetized dogs. American Journal of Veterinary Research 62: 12: 1922 - 1927.

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21. Vickery, R. G., Sheridan, B. C., Segal, I. S. and Maze, M. 1988 Anesthetic and hemodynamic effects of the sterioisomers of medetomidine, an 2-adrenergic agonist, in halothane-anesthetized dogs. Anesthesia and Analgesia 67: 611 - 615.

22. Waechter, R. A. 1982 Unusual reaction to acepromazine maleate in the dog. Journal of the American Veterinary Medical Association 180: 1: 73 - 74.

23.Wetzel, R. W. and Ramsay, E. C. 1998 Comparison of four regimens for intraoral administration of medication to induce sedation in cats prior to euthanazia. Journal of the American Veterinary Medical Association 213: 2: 243 - 245.

(Published - April 2003, courtesy of Dr K E Joubert)


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