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Penile problems in bulls

Many can be caught and fixed at a yearling semen evaluation

Severe penile warts.

When examining young bulls for the first time we as veterinarians look for many conditions besides semen quality that may affect breeding ability. Many of these can be corrected but some result in bulls being eliminated from the gene pool.

Young bulls are more commonly detected with seminal vesiculitis and other infections involving secondary sex organs. Seminal vesiculitis is detected by rectal palpation and the veterinarian will decide then whether treatment, time, or culling is the best option based on the severity of the infection. It results from a young bull being ridden excessively, or from old infections such as navel infection that seeds out in this area. Pus is then discharged in the semen reducing fertility.

Several common physical conditions can be noted when the penis is protruded. A persistent frenulum is one of these. It’s a ligamentous attachment between the sheath and penis that causes the penis to bend on full erection making it very difficult to enter the vagina during breeding. If it is not corrected it can also be the cause of broken penises when the already bent penis is suddenly bent over on impact with the back of the cow.

These frenulums can be identified and incised just after the semen sample is collected. Sexual rest is necessary until it heals and even then it should be rechecked to be sure no scarring has occurred.

Occasionally two persistent frenulums are found on a bull. If they are not detected any attempt to breed this animal can result in ripping with lots of bleeding. Blood is very detrimental to semen quality and fertility suffers. The bleeding reoccurs with each erection so the bull cannot get the rest required to heal the rip during breeding season.

Persistent frenulums are highly heritable so purebred breeders should closely scrutinize breeding forms when purchasing their herd sires. Commercial breeders steer all their bulls so it would be inconsequential to them.

From the Alberta Farmer Express website: Keep an eye on bulls before and during the breeding season

Warts are another common condition encountered on bull penises. These can be surgically removed as long as they do not involve the vital structures on the tip of the penis. Veterinarians simply remove the wart, cauterize the bleeding if necessary suture where appropriate and recheck later for reoccurrences. Warts are invariably very rough and can rip or tear tissue and cause bleeding during breeding. Again fertility is impaired. Very large warts near the tip of the penis can impair nerve supply making it impossible for bulls to hit the mark during copulation. I have not tried to make an attenuated wart vaccine for herds with a high incidence of this condition but I have been tempted to.

There doesn’t seem to be a lot of correlation between body warts and penile warts. Most bulls I’ve encountered with penile warts have no evidence of warts on other part of their body. They have determined that the two types of warts are slight variations of the papova virus. Yes a virus causes warts. Two to three weeks is generally enough time to heal the penis after a wart is removed.

Cuts and abrasions are easy to discover during a visual examination of the penis. Treatment may be necessary but in most cases rest solves these sores. With severe cuts some scarring may occur making full penile extension impossible and these bulls definite cull candidates.

All the above problems clearly identify the need for veterinarians to fully examine the extended penis of the bull during semen evaluation. Most problems found here can be treated provided adequate time is available before breeding season.

In young bulls before puberty the prepuce is tightly adhered to the penis. It pulls away as the young bulls’ erections progress. With this comes some bleeding and any time there is blood fertility may be impaired. If we see this adherence during an evaluation it tells us the bull may be immature and has never been completely erect. We must ensure this can happen before we allow this young bull out into the breeding herd.

Hair rings that strangle the penis can occur when bulls are mounting each other and the hair from the back forms a tight ring around the penis. Most are easily removed but they shouldn’t be ignored. In the worst case I’ve seen the tip of the penis cut off by a hair ring rendering a potentially good bull useless as a breeder. Warts near the tip also make it easier for the hair to wrap around the penis.

It should be emphasized that many of these potential problems can be corrected by carefully paying attention during the first semen evaluation on young bulls. Almost all purebred breeders now have semen evaluations performed so any of these abnormalities can be detected ahead of time and corrected before they ruin a perfectly good bull. Murphy’s Law of semen evaluations stipulates these problems always happen to the most expensive, sought-after bulls so take heed. Have your new yearling bulls semen evaluated.

Roy Lewis, DVM

About the author


Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.



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