Cryptorchidism
Written by AKKPS Member Debra Allen of Allen's Acres
What is cryptorchidism?
There is a condition called cryptorchidism in male pigs with "retained" or undescended testicles. Monorchism is when one testicle is retained and one isn't. Some say bilateral cryptorchidism if both are retained, and some say cryptorchidism to mean either one or both. Oddly enough, if only one testicle does not descend, it's usually the one on the right side.
It may affect one or both testicles, and I have heard of unsuspecting pig parents being fooled by someone saying a pig is neutered when the pig is far from neutered. The procedure to locate and remove the testicles in animals with this condition is much more complex than the standard castration procedure. The veterinarian needs to be skilled and proficient in pigs to reduce the risks of a disastrous outcome. An experienced vet would be ideal, but this is only sometimes possible. Most university vet hospitals have experienced vets on staff.
Cryptorchidism is a genetic disorder; it can be passed onto offspring and can result from inbreeding too. Breeders who pass these pigs off as neutered should be informed that they are NOT neutered and asked if they have proof of surgery. This type of misinformation is unacceptable and people who are passing pigs on as being fixed, knowing they're not, ought to be ashamed of themselves. Since this is a genetic disorder, the cycle can continue for quite some time and lead to significant health complications in pigs who are identified as neutered when they're not.
Castration
Knowing a pig wasn't castrated is very different from learning a pig is a cryptorchid. Kunekunes, indeed all swine, are supposed to be born with testicles descended. It's frustrating when I hear comments about "testicles drop later" or "wait til they're a year or 18 months to drop"…these are simply untruths. It is true that when young (before sexual maturity), the testicles can hide in the substantial fat between their hind legs.
Careful palpation will reveal two firm lima bean-like testicles. They don't grow until testosterone production starts in force when they then expand to fill the scrotum. Reputable and knowledgeable breeders must keep good records of piglets' births and document any not born with two testicles. Never buy an intact male piglet without verifying both testicles are down, OR if you can't, get it in writing that the seller guarantees both are descended. This becomes important later because a cryptorchid should never be bred. It is an inherited condition, and many think it's primarily inherited from the boar, though inheritance might be polygenic. Ignorance of this problem is not an excuse.
When testicles are not descended, testosterone does still get produced. This leads to several more problems.
If you were told your pig was neutered and you see scrotal sacs on the hind end; Your pig is likely NOT neutered. Some testicles remain small and hidden in the fat between the hind legs. Then get larger as hormone production starts. If you were told your pig was castrated and your pig is displaying classic boarish behavior like humping any/everything, you might want to have the vet check your pig out to be sure your pig is not intact. You may have a cryptorchid if your pig is acting boorish and you see nothing filling the scrotum. There is a difference between a pig with behavioral issues and a pig with hormonal problems.
Diagnosing an animal as a bilateral cryptorchid, as opposed to having been previously desexed, is generally difficult to do based on testicular palpation alone. After all, in each case, there will be no testicles felt in the scrotal sac. The only time that testicular palpation may be able to assist in the diagnosis of bilateral cryptorchidism is if one or both of the retained testicles is outside of the abdomen and located within the inguinal canal or pre-scrotal area and, therefore, able to be palpated by the vet.
Palpation of the empty scrotum may give the veterinarian clues about whether or not a pig was desexed (castrated) instead of being bilaterally cryptorchid. Neutered animals tend to have a thick ball or nub of scar tissue within each scrotal pouches. But this is not a foolproof method to be 100% certain a pig has been neutered.
Complications
This condition, left untreated, can lead to complications if not treated. Pigs with cryptorchidism are at a much higher risk for developing testicular tumors and these conditions.
- Testicular torsion (twisted testicle)
- Testicular cancer (testicle cancer)
- Male feminizing syndrome
- Bone marrow hypoplasia and pancytopenia- estrogen toxicity
- Excessive testosterone production- this can lead to super aggressive behaviors.
As mentioned above, animals with bilateral cryptorchidism might be infertile and incapable of making viable sperm; however, their testicles still produce high levels of the masculinizing hormone: testosterone. Desexed males, on the other hand, have very little testosterone. Unilateral cryptorchid boars (one down) can still impregnate a sow. Bad news since it's an inherited trait. Bilaterally cryptorchid animals with plenty of testosterone are much more likely to develop the kinds of "male" testosterone-dependent body features usually attributed to an entire animal.
It is sometimes possible for your veterinarian to locate bilaterally undescended testicles using ultrasound technology. Many clinics have access to diagnostic ultrasound these days, and a skilled operator may be able to identify the undescended testicles. Note, however, that undescended testicles are often small and can be very difficult to find. A negative result on ultrasound does not mean that the animal is not a cryptorchid.
Surgical Discovery
Sometimes a diagnosis of bilateral cryptorchidism (as opposed to monorchism, anorchism, or prior castration) can only be made by surgical exploration. In these situations, the animal is placed under a general anesthetic, and its entire abdomen, groin, and scrotal region is shaved and surgically prepared. Because the missing testicles might be tiny (retained testicles are often a lot smaller than scrotal testicles are—-see photo below) and could be located anywhere from the abdominal cavity, behind the kidney, through the inguinal canals to the pre-scrotal regions, the vet may have to make several incisions to find them. The vet might make an incision into the abdominal cavity, only to discover that one or both of the retained testicles' spermatic cords (vas deferens and testicular blood vessels) disappears into the respective inguinal canal. The vet will then need to make a new incision into the appropriate right and left inguinal (groin) region/s to locate the missing testicle/s. This is the more complicated surgery mentioned above.
There is another condition called testicular atrophy or degeneration (late-onset cryptorchidism). Pigs with this condition are reported to have palpably normal testicles at birth and weaning but only one testicle after 40 days. Ectopic testicular tissue has been noted in many of these pigs. Initially, these masses may be interpreted as metastatic neoplasia, but histology reveals the presence of convoluted seminiferous tables and interstitial cells.
Research
Cryptorchidism is considered to be hereditary. McKenzie (1931) found evidence that such is the case. He mated a gilt from a cryptorchid boar to a crypto-chid litter-mate and roughly 50 percent of the male pigs resulting were crypto-kids. Out of 107 pigs from 12 sows, sired by a normal boar, ten cryptorchid pigs resulted in five of the 12 liters. The boar was not related to the sows, but three of the sows were daughters of the fourth. When the boar was mated to his daughter, a litter-mate to a cryptorchid male, one sow pig, three normal males, and two cryptorchids resulted. McPhee and Buckley (1934), in experiments with an inbred strain of Chester Whites at the United States Animal Husbandry Experiment Farm, Beltsville, Maryland, re- port that continuous brother-sister mat- ing to establish an inbred line provided sufficient evidence for them to postulate that cryptorchidism in swine is a sex-limited, recessive character.
Smith, Robinson, and Bryant (1936) agree substantially with such a hypothesis, while Couvreux (1943) attributes cryptorchidism to a hereditary factor transmitted by the male, dominant in the horse, but recessive in the pig, dog, and sheep.
From the preceding, it is evident that cryptorchid boars should never be used as sires. The loss to the producer should be minimal if the scrotal testicle is removed, and if the animal is marketed before six or seven months of age, the producer should sustain little or no loss.
Summary
In summary, cryptorchidism in swine is a sex-limited, recessive factor of heredity- very nature and is widespread in the swine population. Care in the selection of breeding stocks should prevent its incidence from increasing, and marketing at an early age will, as far as possible, prevent monetary losses from being sustained by the producer.