Castration, the surgical removal of the two testicles, is a routine management practice for male pigs destined for slaughter. The testicles produce sperm and the male hormone, testosterone. Pork from boars, or uncastrated male pigs at slaughter weight, may have an odor during cooking that is offensive to many people. This is called a "boar odor" or a "tainted" odor.
Various techniques are used for castration. The position of the animal during surgery and the method and degree of restraint are dictated by the age and size of the animal. The best time to castrate a pig is between 1 and 21 days of age. Young pigs are easier to hold or restrain, bleed less from surgery, and may have antibody protection from the sow's colostrum. Pigs can be successfully castrated on day one. One of the major disadvantages of castrating early is that scrotal hernias, which are genetic in origin, are more difficult to detect. Boars and gilts from any litter in which one or more pigs were herniated should not be kept for breeding.
For younger pigs, it is possible for one person to hold the pig with one hand or between the knees and also do the castration. For pigs several weeks old, one person holds the pig by the rear legs while another person does the castrating. A mechanical pig holder can be used.
Once the pig is restrained, clean the scrotum and surrounding area with a cotton swab soaked in a mild disinfectant. A disinfected, sharp, castration knife, scalpel, or razor-blade type instrument can be used to make the incision. Examine the testicles before making the incision to determine if there are two of similar size. If there is a scrotal enlargement, it could indicate a scrotal hernia or rupture. Do not castrate the pig unless you are trained to repair hernias, as the pig's intestines may be forced through the incision. Sometimes the testicle is removed before a scrotal hernia is discovered. If this happens the herniation must be repaired by suturing immediately.
If one or both testicles are not found, the pig may be a cryptorchid, meaning that the testicle(s) failed to descend through the inguinal canal from the abdomen during development. When this condition is noticed, ear notch the pig and make a record of it. Often, the testicle(s) will descend to a normal position as the pig grows. The pig should be castrated later, after the testicle presents itself.
With one hand, tighten the skin over the scrotum to help expose the testicle and the site for the incision. With the castration instrument, make two incisions about as long as the testicles near the center of each. Cut deeply enough to go through the outside body skin. Cutting or not cutting the white membrane (tunica vaginalis) which surrounds the testicle is an individual preference and is optional on small pigs. Squeeze, or pop, the testicles through the incision. If it is difficult to get the testicle through the incision, enlarge the incision slightly at the end closest to the tail.
Pull out the testicle toward the tail at a right angle to the length of the body and cut the cord close to the incision. Do not pull straight up on the testicle. Repeat the procedure for the second testicle. It is best not to apply antiseptic because it causes the pig to sit and rub dirt and debris from the floor or bedding into the incisions, causing more harm than antiseptic does good.
Later, observe castrated animals for excess bleeding or the presence of tissue or intestines (hernia). Cut off any cord that may be protruding from the incision as this may serve as a wick for infection but make sure it is not intestine. If intestines protrude, gently push them back through the opening and close up by suturing the tunica vaginalis. It is much easier to replace the intestines if the tunica vaginalis covering the testicle is not removed during castration.
Side Cutter Method of Castration
The side-cut method of castration is successfully practiced in some parts of the U.S. It is a simple technique that is performed between 4 and 10 days of age, when pigs are small, requiring only one person to do the job. Problems can be encountered when pigs are castrated at less than 3 days or older than 10 days using this method.
For this method (Hartman and others, 1979), the pig is held with one hand by one leg, belly outward. With the middle finger, or whichever is comfortable to use, the testicles are made more pronounced. The resulting fold of skin is where the incision, is made. Disinfected side cutters are positioned about two-thirds of the way into the fold with a clean cut made directly through the scrotal tissue (right of the midline). After the cut on the right side has been made, a similar incision, but to the left of the midline, is made. The testicles are made to pop out through the incisions as they are pinched with the thumb and forefinger of the same hand that is holding the pig. Important: Press very firmly with the thumb against the pelvis of the pig in front of the scrotum when pulling the testicles out with the side cutters so that the cord will break off at the point where the thumb is pressed. Otherwise it is common to cause a hernia. There is little or no bleeding with this method. The testicle, after it is exposed, is grasped with the side cutters. Care is taken to avoid cutting through the cords beneath the testicle as they are now ready to be pulled out with the testicle. The right testicle and associated cords are pulled out slowly and steadily. There is no cutting of the cords in this method as they are pulled out completely with the testicle. Remove any loose cord tissue left outside the incision. Nothing but the disinfected side cutters touches the exposed tissue.
For beginning pork producers, it is often best to have a veterinarian or other skilled individual demonstrate the proper techniques of castration. Some State Extension Services also conduct swine farrowing schools that teach castration and other skills in taking care of baby pigs.