Learning about BVD

On my farm practice placement one of the diseases the vets talked about a lot was bovine viral diarrhoea (BVD). Apparently BVH has a huge economic impact on cattle farming: it can cause poor performance in herds for many years without being treated as farmers may come to accept this as normal. Ongoing infection and re-infection happens via an interesting mechanism including intrauterine transfer to calves and Persistent Infected (PI) individuals constantly shedding virus into the herd’s housing.


What does BVD look like?

BVD infection leads to respiratory problems and poor fertility, as well as compromising the immune system and making cattle more vulnerable to secondary diseases like pneumonia and scouring. In pregnant cows it can cause abortion, embryo death or birth defects, particularly neurological problems. Where cows are infected early in pregnancy their calf becomes exposed to BVD antigens before their immune system is developed enough to recognise it. These calves, if they survive, become the sinister PI cattle responsible for infecting herds more broadly.

What’s the deal with PI cows?

BDV can be transmitted directly or via the environment between infected cows, replicating and causing infection once it touches epithelial cells. Normal individuals will produce antibodies and can become immune, although some will have chronic infections in organs the immune system struggles to reach such as reproductive organs. PI cows, however, “see” the virus as self because it was present before their immune system formed properly. They can never produce antibodies and go around shedding viral material at a thousand times the rate of a normal infected cow.

Many PI calves fail to reach adulthood, often dying from mucosal disease or cerebellar hypoplasia, the aforementioned neurological condition they are likely to be born with. But those that do grow up continue to infect the cows they live with for their entire lives. Identifying and culling these individuals is crucially important to controlling BVD in a herd and restoring herd performance.

What can be done?

As well as removing the PI cows from a herd, biosecurity and vaccination are both important tools. Milk, ear tag and blood samples can be used to test for the presence of antibodies or antigen and look at the infection status of the herd whilst measures such as double fencing and only buying in BVD-free animals can help keep the disease out.

A voluntary BVDFree scheme started in July aiming to eradicate the disease from the UK by 2022. Several Scandinavian countries have proved this to be possible already and practices are encouraging their clients to sign up and gain BVDFree status. This can be expensive but does lead to greatly improved performance of the farm and can be a selling point, for example selling stock certified as BVD-free.

BVD was an interesting disease to learn about even if we never actually dealt with it during my placement week. I’ve listed my references below but a lot of this came from the vets at the practice who were fantastic teachers!

NADIS

RVC BVDFree

The Cattle Site

Ususal disclaimer: I’m not a vet, not even a vet student yet, so please don’t use my blog for vet advice! If you notice things I’ve got wrong or not understood properly, please feel free to point them out. Thanks 🙂

 

Advertisements

The death of a cow.

On Friday I shadowed a vet whilst he observed and certified the emergency euthanasia of a cow. This was a new procedure for me and one which would once have made me very sad. However the welfare needs of the cow and the professionalism of everyone involved meant that although it was a shame to see an animal killed before its time, it was clearly a necessity and it was carried out in the proper fashion.

The cow was a dairy Holstein or Fresian type with a non-recoverable injury to one or both hind limbs. When we arrived on the farm she was laid in a frog-like position. Apparently there have been studies of how well a cow’s collapsed position predicts her chance of survival and if she’s landed this way, the prognosis is very poor. She did not try and move away as the farmer, vet and slaughterman inspected her and was clearly in a sorry state.

Continue reading “The death of a cow.”

What happens at the slaughterhouse?

One of the unavoidable truths about farming is that most animals are killed before their “natural” lifespan is up at the abattoir. Although their time at the slaughterhouse is brief, this is a time that can have significant animal welfare implications, be they good or bad. Rather than shy away from this point I’ve decided this week to look into how animals are slaughtered and the different ways this can be achieved humanely. Although for a vegetarian this might seem strange it matters a lot to me because almost all of the livestock I ever care or contribute to the care of will end its life in an abattoir. This means it’s important to me that slaughter is done right.

Continue reading “What happens at the slaughterhouse?”

Lambing in Derbyshire

I’m really going to struggle to put down on paper my enjoyment and learning over the six days spent on a Derbyshire farm during lambing. “I could have stayed forever” would be a good summary. I’ll try to be a bit more structured though and avoid waxing lyrical about sheep. In all honesty I’ll struggle – this placement has done a lot to cement my interest in livestock medicine and I wish I could spend more time learning about it before applying to uni.

Continue reading “Lambing in Derbyshire”

Common health problems in dairy cows

I’ve seen several articles recently which compare dairy cows to high performing athletes. Although they don’t inspire the same awe in the public audience or compete at the Olympics, the lactating cow’s metabolism works at an impressively high rate to convert feed into huge volumes of milk. Unfortunately, this incredible production comes at a cost and our dairy cows do suffer from a variety of common health problems, the most frequent of which I’ve been reading up on.

Continue reading “Common health problems in dairy cows”

A dangerous job – on Countryfile!

My little sister sent me a link to this episode of Countryfile where they talk about the dangers vets face when working with livestock. I think they used a lot of the same references as my post on the same subject. The programme is available for a few more weeks if you want to take a look.

Oh and bonus material with this post….