6 Sedation, Analgesia, Anaesthesia and Euthanasia Azaperone is the only sedative licensed for use in pigs in the UK. The dose is 2 mg/kg. It is not always very effective except when given im with 1 IU oxytocin/10 kg to gilts that are savaging their newborn piglets (Fig. 6.1). It is also licensed to prevent and cure fighting (including regrouping of pig-lets, porkers and fattening pigs): pigs from different litters or pens may be brought together into one pen immediately after administration. All animals should be treated. After a few minutes they lie down together for about 2 h, irrespective of their origin. Afterwards violent fights are unlikely to occur. During the time of treatment, untreated pigs should not be admitted to the pen. The product will not prevent aggressiveness in noncastrated adult boars. Newly weaned piglets may be treated together with other routine treatments on arrival at the fattening unit. Fighting animals become quiet shortly after the injection. The animals are unlikely to fight even after the effect of the drug has worn off. The drug is licensed to treat stress in the form of restlessness, anxiety, nervousness and excitation, e.g. because of pain: the dose for this between 1 and 2 mg/kg. The dosage should be adapted to the degree of excitation. If the animal is very nervous, the product may be given in divided doses at 15 min intervals. Azaperone is licensed to transport boars: the animals should not be brought together within the first half hour following the injection because they are still likely to be aggressive; they should be left alone in a quiet environment during the induction period (approximately 30 min). The dose of 1 mg/kg should not be exceeded as a higher dose may cause the penis to be extruded, which may then be damaged. The drug may be used for transport of weaners at a dose of 0.4–2 mg/kg. It should be administered 15–30 min before transport to reduce mortality and weight loss during transport in order to prevent fighting. Animals should be given enough space to lie down. It is important to make sure there is adequate ventilation during transport. The drug may be used when there is cessation of parturition due to excitation, as an obstetric aid during normal delivery, inversion of the vagina, prolapse of the uterus or pathological straining. Azaperone may be used for premedication before local and general anaesthesia. The dose can be between 1 and 2 mg/kg. There are many indications: blood sampling, diagnostic examination, castration, prolapse of the rectum and wound treatment. Azaperone should not be used in the transportation or for regrouping of pigs which will be slaughtered prior to the end of the 10 day withdrawal period. Fig. 6.1. Gilts may savage their piglets. There are four useful injectable NSAIDs licensed for pigs in the UK: flunixin, ketoprofen, meloxicam and tolfenamic acid (see Appendix). They all follow similar pharmacokinetic pathways and therefore only a single drug needs to be carried by the ambulatory practitioner. Although these four NSAIDs are not licensed for oral use in pigs in the UK, they can be used under the cascade principle as the only licensed NSAID for oral administration is sodium salicylate, which has limited usage. Flunixin is available as a paste which can be given directly into a pig’s mouth or in a sandwich of bread with chocolate spread. Flunixin is also available as granules. These can be sprinkled on the pig’s food or once again put in a sandwich. Meloxicam is available as a liquid for oral administration to horses. This can easily be put on pig’s food. Care should be taken with the dosage as the syringe supplied with the medication is calibrated for the weight of the horse. A dose needs to be worked out for a daily dose for the individual pig on a weight basis. For smaller pigs requiring analgesia with NSAIDs, tablets suitable for dogs, which are normally very palatable, can be given orally. This is allowed under the cascade principle. Butorphanol is not licensed for pigs but may be used under the cascade principle. It is a very potent analgesic when given at 0.3 mg/kg by intramuscular injection. Unlike NSAIDs the analgesia lasts only for a maximum of 6 h. Injectable ketoprofen given to sows suffering from postpartum dysgalactiae has been found to reduce pre-weaning piglet mortality. It is advisable that sows receive appropriate antibiotic treatment immediately after farrowing and that they also receive a single intramuscular injection of ketoprofen at 3 mg/kg. Anaesthesia is not well documented. However, masking very young piglets is quite easy with isoflurane or halothane without premedication. It should be remembered that certain pigs will possess a gene which makes them more susceptible to death from halothane anaesthesia. Owners should be made aware of this before it is used for anaesthesia. A signed disclaimer should be obtained from the owner. The 15–25 kg weight range of pig can be masked down with isoflurane or halothane after premedication with azaperone at 2 mg/kg (Fig. 6.2). This will require good manual restraint for pigs in the heavier ranges. Unless this is available it is advisable to use a combination of drugs as described below for large growing pigs. It is advisable to weigh the pig accurately and obtain a signed disclaimer from the owner as such combinations are not licensed for pigs. A combination of drugs given im in the same hard, non-disposable syringe and a 14 gauge needle is the author’s preference. The dose is 0.2 mg xylazine/kg, 10 mg ketamine/kg and 2 mg butorphanol/10 kg. It should be acknowledged that these products are not licensed for pigs in the UK either alone or in combination. This combination will give approximately 20 min of general anaesthesia, after a gentle induction which takes approximately 5 min. It also gives a slow gentle recovery. It is important that the pig is not stimulated during induction or recovery, but is allowed to lie quietly in lateral recumbency.
Sedation
Analgesia
Anaesthesia
Piglets
Older growing pigs
Large growing pigs and adults
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