Use of xylazine hydrochloride, Ketamlne hydrochloride and atropine sulphate for anaesthesia in donkeys

Abstract

The veterinary anaesthetist is called upon to deal with a number of species of animals which exhibit great variation in size and temperament as well as in anatomical and physiological development. Apart from differing response of each species to the various anaesthetic agents, there is often marked variation in response between breeds within each particular species (Hall and Clarke, 1983). The sedative and anaesthetic effects of xylazine hydrochloride not only show considerable variation from species to species but, the variation is also exhibited among individual animals of the same species (Neophytou, 1982). Although the use of xylazine hydrochloride and ketamine hydrochloride independently or in combination in various animal species has been reported (Lindley, 1980; Byagagaire, 1982; Mbiuki, 1982; Allen et al., 1986; White et al. 1987) very- little has been reported about their use in donkeys. This project was designed toevaluate the use of xylazine, ketamine and atropine for general anaesthesia in donkeys. A total of 30 experiments were carried out on 30 donkeys, 25 being males and 5 females. They were aged between 2 to 11 years and weighed between 80 and 200 kg. The donkeys were divided into 6 groups of 5 animals each. Anaesthetic trials were carried out using xylazine hydrochloride, ketamine hydrochloride and atropine sulphate. Xylazine was used at a dosage of 2.0mg/kg body weight, ketarnine at 4.4 mg/kg body weight and atropine at a total dose of 25 mg. Atropine was injected subcutaneously, and the other drugs intramuscularly. (xii) Anaesthetic times were recorded from the time the trial drug(s) was/were injected until 2 hours were over. The anaesthetic parameters monitored were weak time, recumbency time, down time, attempt to rise time, standing time, unconsciousness time, muscle relaxation, reflexes, pain sensation and other behavioural changes attributed to the injected drugfs). The other physical parameters including the heart rate and respiratory rate were recorded every 5 minutes during the experiment and the rectal temperature every 15 minutes. A jugular-blood sample for routine hematology was taken 10 minutes before injection of the trial drugts), 1 hour and 5 hours after injection of the trial drug(s). A great deal of variation in reaction to the drugs was seen within groups and between groups. The drug combinations achieved weak time earlier. Atropine- Ketarnine-Xylazine combination achieved weak time in 5.20±1.30mins while xylazine alone attained it in 10.00±2.12mins and ketamine alone in 6.00±1.58 mins. Ketamine alone and ketamine-xylaxine combinations made donkeys go into recumbency. The drug combinations ketamine-xylazine and atropineketamine- xylaxine made the donkeys stay in recumbency for 24.80±13.80 mins and 46.60±17.86mins respectively .. This was longer than for ketamine alone and atropine-ketamine whose times were 18.80±9.41 and 10.00±11.55 mins respectively. Recovery was much faster in 'donkeys. injected with ketamine alone (124.00±9.61 mins) and longest for donkeys injected with atrophine-ketamine-xylazine combination (212.00±21.67 mins). The combinations gave good muscle relaxation while the individual drugs did not. The combinations eliminated the pedal reflex and the palpebral and anal-- reflexes were weakened. The drugs when given separately did not eliminate any of the reflexes tested for. Analgesia given by the drug combination was moderate 'to good. Salivation, protrusion of the penis and drooping of the lower lip were evident in most of the donkeys where xylazine was used either alone or in combination. No significant (P>O.05)rise in mean rectal temperature was recorded where ketamine alone and the combinations were used while a slight decrease was recorded where xylazine alone was used. Xylazine alone reduced the mean respiratory rates whereas ketamine alone and the combinations caused an increase in the mean respiratory rate although these changes were insignificant (P>O.05). The mean heart rate for donkeys injected with xylazine alone decreased while it increased where ketamine was used. The combination caused a decrease in mean heart rate. However, all these changes were not significant (P>O.05). The effects of the drug(s) or drug combinations on the blood constitutents were quite variable. -However, xylazine alone and the ketamine-xylazine combination caused a significant (P<O.05)decrease in PCV and Hb values in the groups of donkeys where they were used whereas the groups that had atropine in addition had an insignificant (P>O.05) decrease. No significant (P>O.05)changes were recorded for the other blood constituents in other groups where the drugs were used alone or in combination. From the results, it can be concluded that ketamine-xylazine combination gave uneventful immobilisation and smooth recov~ry from anaesthesia which was not observed when the individual drugs were given. Analgesia was present in cases to which the drug combination was administered but this was of short duration. Muscle relaxation was present when the drug combination was given. The presence of atropine did not have a marked influence over salivation where it occurred. This was also the case with the heart rate. When the individual drugs were used, the presence of atropine helped stabilize the respiratory rate. The use of the drug combination of ketamine and xylazine with atropine for general anaesthesia in donkeys is recommended for surgeries of short duration. The use of ketamine alone should be avoided due to self inflicted trauma that is likely to occur due to excessive involuntary muscle activity it causes.