Eamon O’Connell: BVD eradication is on the horizon, but far from complete

Yes, it’s an easy way to sell whatever you have to sell, but it’s also a haven for the world’s lonely hearts and professional hoop-kickers, along with the odd prank call thrown in as an encore becomes.

On the other hand, when you’re shopping it can be fantastic to find what you want, but you might have to, as the saying goes, “kiss a lot of frogs before you find your prince”. It’s certainly a case of caveats – let the buyer beware.

When it comes to selling animals, as with any sale, if you have your wits about you you will find what you are looking for. The farmer I spoke to was wondering about the vaccination status of a group of heifers that interested him. “Vaccinated against BVD?” To which he replied: “Sure, I thought that was settled at this point.” Unfortunately, as I will now explain to you, this is far from the case.

BVD stands for Bovine Virus Diarrhea Virus. It is a particularly nasty virus that can affect cattle in a number of ways. When BVD virus circulates in breeding animals such as cows and heifers in the herd, reproductive problems such as miscarriages and poor conception rates can occur.

When an animal comes into contact with the virus, it can enter the animal’s system, stay there for a while, and then be transmitted to another animal nearby. This is called transient infection and allows the virus to circulate around a herd for a long period of time.

If a pregnant cow comes into contact with the virus between two and four months of age, the virus will attack the fetus. Sometimes the cow aborts and sometimes the fetus does not develop properly, ultimately resulting in a calf being born with serious defects, such as a shortened tail and legs, or even an underdeveloped brain.

In other cases, the virus lodges in the fetus, which has not yet developed an immune system. The virus makes itself part of the calf, turning that calf into what we commonly know as PI – permanently infected. These calves appear normal at birth but shed the BVD virus in large quantities, putting pressure on the entire herd and putting all pregnant cows at risk.

Most PI cattle eventually die before they are two years old, often from a condition called mucosal disease. This disease results from a mutation of the BVD virus in a PI animal. The animal develops severe diarrhea that does not respond to any treatment. A PI animal’s immune system is weak at best. Therefore, if mucosal disease does not occur, they will die of other diseases such as pneumonia.

It is these PI calves that we look for when using BVD tagging on any newborn calf. An animal can only be born as a PI. You cannot become one later. Once an animal is born a PI, there is no turning back – it will remain a PI throughout its life.

The BVD eradication program began in Ireland in 2013. The theory of the program was simple and on paper it looked like it would work. Each animal born on the farm was tested for the BVD virus by taking a skin notch from the ear with a specially designed BVD tag.

Each animal identified as a PI was retested to confirm that it was a true PI and not transiently infected. If the test was positive, the calf in question was removed and the mother was also tested. In theory, this should have gone a long way towards ridding the country of this terrible disease.

Unfortunately, some problems soon became apparent. A PI calf mostly looked like a healthy calf. It was a very hard pill to swallow, especially for mother farmers when they were told they had to get rid of a prize-winning calf because it tested positive for a disease ‘invisible’ to many farmers.

Anecdotally, I’ve heard many stories of PI calves being isolated from the herd in an “outdoor yard” until the calf was fit enough to go to the factory. Of course, I’ve never heard of a story that ended with the calf dying of mucosal disease, but not too many would admit that. The compensation value was also far off the mark for the farmers.

A few pounds for the calf wasn’t enough after the mother farmer had fed the cow for nine months. Many farmers were willing to risk it, hoping the invisible disease wouldn’t develop into something visible.

Slowly but surely, the eradication program has made progress in recent years. Now, at the end of 2022, we are close to being BVD-free and therefore the program has been upgraded by a few notches. If a calf passes a marking test, the herd is immediately restricted. The calf must be sent to the Knackerei immediately.

Three weeks after calf sacrifice, the entire herd is blood tested for BVD and each breeding bitch over 12 months of age must be vaccinated once with live BVD vaccine or twice with inactivated BVD vaccine. They must be vaccinated again the following year. The vaccine, like the blood test, is paid for by the Ministry of Agriculture. If removed within 10 days of the positive result, compensation of €220 for suckler calves and €160 for milk heifer calves is paid. It may not seem like much, but we’re on the home stretch to eradicate this disease, so not many options remain.

Dairy bull calves are worth €30 and that is more than many of them are now worth. If you have a PI and choose to ignore the protocol, your herd will be restricted and you will not be able to buy or sell animals. So take the punch and get rid of this disease once and for all.

Any female that is pregnant at the time a PI is present in the herd is at risk of having a PI calf in a few months. These cows/heifers are called “Trojan beasts”. These cows look healthy on the outside and are negative at blood sampling and even vaccinated. However, there is still a chance they may be carrying a PI calf. These animals should not be sold until their calves have been born and tested negative for BVD.

Biosecurity is of paramount importance, so check for inadequate perimeter fences and disinfect shared farm equipment.

If a neighboring flock has a PI, you will be notified if you share a boundary with that flock. The first thing to do in this scenario is to check all of your border fences. It is important that your livestock does not have physical contact with your neighbour’s livestock.

See animalhealthireland.ie for more information about the disease.

Eamon O’Connell is a Veterinarian at Summerhill Vet Clinic, Nenagh, Co. Tipperary