Final results of 3-year bull breakdown PDS

ASHEEP & BEEF’s Producer Demonstration Site (PDS) project, “Preventing Bull Preputial Breakdown by Vaccination”, funded by Meat & Livestock Australia (MLA) and facilitated by Swans Veterinary Services has concluded after 3–years of surveillance. The project strongly demonstrated the value of vaccinating virgin bulls prior to their first joining with either of two commercially available vaccines with the goal of reducing the incidence and/or severity of bovine herpes virus infections.

Figure 1 Bull penis with severe case of IBP.

ASHEEP & BEEF would like to thank MLA for funding the project, Dr Enoch Bergman and Swans Veterinary Services for facilitating, our local producers for participating, and Zoetis Animal Health for providing access to free Rhinogard vaccine for the duration of the project.

Read on for Enoch’s summary of the final results.

Exploding willy syndrome

Article by Dr Enoch Bergman, Swans Veterinary Services

As part of a Meat & Livestock Australia Producer Demonstration Site project, we have just concluded compiling information from three years of survey work and veterinary investigation of cases relating to Infectious Bovine Balanoposthitis (IBP), colloquially referred to locally as “Exploding Willy Syndrome”. Whilst no bovine genitalia have ever actually exploded, the moniker definitely provides a fairly succinct description of the reality! Read on for a description of the syndrome and some of our findings.

IBP is a condition caused by a herpes virus in cattle. It causes ulcerative inflammation of the penis and prepuce of bulls and of the vulva of cows. Like all herpes viruses, infection is permanent, often going into dormancy, later to “recrudesce” (return) when animals are stressed. In this way, virgin bulls working with other older bulls or merely by being in contact with young cows can become infected during the joining process.

IBP is likely impacted by a number of infectious, environmental and genetic contributors to the syndrome. Regardless, many cases of IBP may be initiated by the herpes virus, leading to secondary infection, and damage to the bull’s prepuce.  Sometimes, the preputial swelling renders the bull unable to retract his penis, resulting in further damage.

There are 3 keys to managing IBP successfully

1. Vaccination

2. Early Recognition

3. Treatment and sexual rest.

Figure 2: Rhinogard applicator & vaccine.

Vaccination:

The targeted vaccination of virgin bulls can be accomplished through the use of  commercially available vaccines, either Rhinogard and/or Bovilis MH + IBR.

Rhinogard, produced by Zoetis, is a modified live vaccination administered intranasally requiring a single dose.  The vaccine is available in either 10 or  50– dose packets which are reconstituted with either 20 or 100mL of saline respectively.  Administer 2mL intranasally using the Zoetis-designed applicator.

Figure 3: Bovilis MH + IBR.

Bovilis MH + IBR developed by Coopers is an inactivated or killed vaccine requiring two 2mL doses to be delivered subcutaneously in monthly increments.  It is available in 100mL or 250mL packs.  No reconstitution of the vaccine is required.

Swans Veterinary Services recommends that studs vaccinate their sale bulls prior to sale, but also recommends that producers provide boosters to bulls purchased from studs already vaccinated. Producers should administer whichever vaccine they choose  one to three weeks prior to joining.

Early recognition:

IBP often progresses rapidly, and can have catastrophic consequences. By remaining vigilant through joining, producers can remove affected bulls promptly, improving the chances of recovery for subsequent seasons.

Treatment and sexual rest:

Sexual rest is critical for improving the likelihood of adequate recovery. Broad-spectrum antibiotics and anti-inflammatories can further improve outcomes. Once infection and inflammation have subsided, your bull may need veterinary assessment to see if he will be able to function adequately next season. Many bulls are culled due to permanent damage to their prepuce and/or penis as a result of infection, however, sometimes damaged bulls can be salvaged. Using an Electroejaculator (a device normally used to collect semen from bulls), a veterinarian can evaluate whether a bull is capable of exteriorizing its penis, achieve an erection, and likely to still be able to serve a cow.  In some recovered cases, bulls with preputial scar tissue may be surgically repaired (via circumcision) in order to restore service capability in subsequent seasons. In some severe cases, affected bulls unfit for transport may require veterinary treatment including surgery to allow salvage.

Our local producer demonstration site project

Over three years (2023–2025), Esperance beef producers were surveyed, resulting in just over 150 data sets accounting for close to 3500 bulls. Over the same time period, local producers were given access to free Rhinogard vaccines provided by Zoetis and extension work helped raise awareness of the syndrome, vaccine options, and local results.

The results of the PDS have strongly supported the use of the two commercially available herpes virus vaccinations to reduce premature bull breakdown associated with balanoposthitis in virgin bulls. Over the course of the project, each year a higher proportion of  producers surveyed reported that they had chosen to vaccinate prior to joining, with a strong  indication that they would likely continue to vaccinate in the future (scoring an average of 9.7 when asked how likely they were to consider vaccinating for bovine herpes virus on a scale of 1–10).

The survey data strongly demonstrated that virgin bulls were more likely to break down during joining with penile issues whilst older bulls were more likely to break down during joining due to lameness.

The PDS strongly demonstrated a reduction amongst vaccinated bulls in the proportion breaking down during joining due to penile injury over all three years of the project.

Please keep your eye out for an opportunity to share your thoughts with ASHEEP & BEEF about the syndrome and the project as post-project surveys are distributed. In the meantime, strongly consider protecting your virgin bulls prior to joining and keeping your eye on them during their first mating season! Please contact Swans Veterinary Services or reach out to ASHEEP & BEEF if you have any further questions or are seeking advice.

The success of producer demonstration site projects

Producer Demonstration Sites are an excellent vehicle for the dissemination of information within producer groups.  Beyond that, it allows producer groups to share some of their local success with producers across Australia through the extension arm of Meat & Livestock Australia. Thank you so much to all of our local producers who helped make this project a success raising the profile of our vibrant agricultural community and our producer group ASHEEP & BEEF!