Anesthetics

ANESTHETIZING POTBELLIED PIGS

by Chris Christensen


Note:  Recently, we have been introduced to an injectable or oral drug for anesthetic purposes, Midazolam.  It comes as an injectable, but can be placed on a small piece of bread and be orally fed to a potbellied pig.  Orally it takes about an hour to take affect, and injected about 10 minutes to take effect. {Our veterinarian has also started successfully administering Midazolam rectally with a syringe (no needle).  He has also had great success with squirting Midazolam up the nose.  The dose is 0.4mg/kg Midazolam.  Pigs need to be left quietly for 30mins before any procedure is started.  Works very well in most situations, and acts much quicker than the oral dose.}  It does not necessarily induce total unconsciousness, but certainly makes standard procedures on a potbellied pig possible.  It also makes an excellent preanesthetic to calm the pig before administering oral gases.  As with all anesthetics, it should be used by your veterinarian, but appears to be safer and certainly more portable than Isoflurane gas.  It could also be used to calm a pig before placing it in a squeeze chute.  Precautions must be taken, as with all anesthetics, not to reintroduce your pig to other herd mates until all anesthetic has totally worn off.


Many procedures can be done on a potbellied pig with the pig not anesthetized.  Hoof trimming, tusk trimming, shots, etc. can be performed with the pig restrained either vertically resting on its hindquarters or horizontally on its back.  Even better is a pig tilt table where the pig is restrained in a squeeze chute and tilted on its side for the procedures. 


In some situations the pig will allow these procedures to be performed while it is lying on its side at rest.  This usually only occurs if the owner started mimicking these procedures on the pig while it was quite young and has continued to do this, making it a normal part of the pigs life. 


Usually, the pig will have to be restrained or anesthetized.  Restraining the pig on its tail or back will probably be noisy and unpleasant, and it will stress you and the pig.  In many cases it will be the only choice, but with older or overweight pigs it can be quite dangerous for the pig.  In these situations a veterinary hospital with a tilt table squeeze chute is very helpful. 


The other option is to anesthetize the pig.  The safest method for anesthetizing a potbellied pig is the use of Isoflurane gas.  This will usually and most safely be accomplished at a veterinary hospital.  Pigs are very sensitive to anesthetics and there are specific ways anesthetics need to be used with the potbellied pig.  Also, again overweight and older potbellies are at risk with anesthetics.


We usually start this procedure with the pig on the floor in the lower half of its crate with the owner holding or restraining it while it is sedated using a full face mask. The pig is then placed on a table and the full face mask is replaced by the proper sized "cat mask" (looks like a sink plunger with the edges rolled in) which fits over the snout allowing access to the mouth area.

“Cat Masks” available from http://www.ambickford.com
To see these masks being used open:
http://www.youtube.com/watch?v=WtpoSZ6AGTs


At this time the Isoflurane setting should be being reduced.   As the gas percentage is reduced the pig may become slightly conscious.  The goal is to try and keep the pig in the range right at the edge of being conscious.  When procedures are over, the pig is returned to the crate. The Isoflurane is turned off, and Oxygen is administered as the pig wakes up.  There may be some slight reaction as the pig becomes fully conscious, but nothing like what occurs when a pig comes up from injectable anesthetic.  The greatest problem we see with Isoflurane occurs when the person administering the Isoflurane gets distracted or busy and does not monitor the gas percentage properly putting the animal so deeply under that it does not recover.  Again anesthetics are not good for or entirely safe for any living thing, but high levels of stress (terror) aren't either.

Notes:  I am offering the following suggestions as percentages of Isoflurane gas to be used when anesthetizing potbellied pigs.  Understand that I am not a veterinarian or an anesthesiologist.  I have worked with veterinarians and anesthesiologists on well over a hundred pigs, but it is recommended that a veterinarian not familiar with potbellied pigs should consult with other potbellied pig veterinarians before attempting to anesthetize a potbellied pig.  Initial settings are usually between 3% and 5%.  If any preanesthetic (Midazolam is recommended) has been used, 3% may be sufficient, but a 3% setting on a fully alert pig will probably result in an extremely long period of restraint before the pig is sedated.  A 5% setting works quickly, but caution must be used to constantly monitor the pig and to back off the percentages immediately upon the pig becoming sedated.  Once the initial sedation has been accomplished, begin backing off the gas to 3% and then down to 2% or 2.5%.  If the pig seems to be remaining sedated at these settings, they should be reduced to 1.5% or less if possible.  Constant adjustment to keep the pig on the edge of consciousness will be necessary.  The lowest percentage possible should be tried for.  Also be aware that each pig will react differently to sedation.  Some will sedate easily.  Some will not.  Some will recover almost immediately.  Others will be slow to revive.  At the end of the procedure immediately administer Oxygen until the pig becomes conscious and alert.

Injectable anesthetics have been used on these pet pigs from the beginning either as a preanesthetic before administering Isoflurane gas or as the only anesthetic.  This is no longer considered to be safe.  In situations where injectable anesthetics are the only option, an experienced vet who knows how to do it is essential.

Dr. Lisle George of UC Davis Veterinarian Medical Teaching Hospital says of injecting the anesthetic Telazol, "I insist that the pigs be given the drug with a 3.5 inch spinal needle inserted into the semimembranosus/semitendinosus muscles (hams). The needle must be inserted at least 2/3 of the length before the drug is injected. Standard 1.5 inch long needles deposit the drug into the fat, and that leads to recovery problems...For foot trims and other procedures where we don't want to anesthetize the pigs, we restrain them on our pig tilt table. The pigs are tilted onto their sides while being restrained in a squeeze chute."

Also, beware if you have multiple animals and one has been sedated. Keep the sedated animal away from the rest of the "herd" until it has fully recovered, plus an hour or so.  Reintroducing a not fully recovered animal to the herd can cause a readjustment of the herd order (i.e. fighting).  Always observe the herd after any animal is reintroduced and be prepared for possibly serious altercations.  We have seen cases of serious injuries after animals have been reintroduced due to fighting with the other members of their "herd".


                                                                           Take two pigs and call me in the morning.

California Potbellied Pig Association, Inc