This week, my phone has been receiving frequent WhatsApp alerts from local veterinary laboratories alerting me to confirmed cases of Schmallenberg virus (SBV) in lambs and calves this spring.
I remember when I graduated in 2013. It was just that spring that Schmallenberg was wreaking havoc throughout Britain, especially among flocks of sheep. With the birth of a deformed lamb.
Again, in the spring of 2019, we experienced a series of cases of malformed deliveries that were confirmed as Schmallenberg cases in certain areas of Cork. It was an unforgettable spring of caesarean section.
The SBV virus was discovered in the German town of Schmallenberg in 2012 after a case of a malformed stillborn lamb was submitted for further investigation. Similar to how the bluetongue virus is transmitted through the midge population, a vector is required for the spread of this virus.
Biting a pregnant cow, sheep, or goat can transmit the virus to the fetus, causing abortion or stillbirth with deformities.
Because of this, minimal disease may be seen for a few years, but when immunity declines and the herd or herd loses immunity again, the disease can suddenly spread again.
If a non-pregnant animal is infected, mild to moderate symptoms may occur, including fever, loss of appetite, decreased milk production and, in some cases, diarrhea. Fortunately, animals usually recover within a few days, even if supportive care is required.
If a midge bites an immature animal during the early stages of gestation, less than 60 days in cattle and 25 days in sheep, miscarriage or deformed stillbirth can occur.
Stillbirth most commonly occurs with a combination of bent and constricted limbs/tendons, fixed limbs, curved spine, short lower jaw, or enlarged, dome-shaped head.
Calves and lambs may also be born alive and appear physically normal. However, neurological symptoms such as standing with legs spread, grazing stars, and even blindness can occur.
Other diseases and genetic defects can also cause malformations and neurological signs in calves and lambs. Your local veterinary laboratory is the only way to confirm the SBV virus.
I remember the first case of SBV in a cow that I saw. When we arrived, the farmer told me that his front legs wouldn’t straighten and he could feel his head, but “something wasn’t right.” What can be confusing is that your legs look smaller, so there should be no reason for your labor failure to develop.
In some cases, the front legs are normal, the back is bent, and the hind legs are fixed in a bent position and become stuck in the pelvis. In another case, my calf was like Superman, putting one front leg in front of me and bending the other back over my chest, and I couldn’t bend my leg to put it in front of me.
One of the sections I did on Schmallenberg’s calf was very difficult. Because the calf was twisted into a ball, the incision was particularly long and it was difficult to get the calf out.
At that time, the suture material was not spared, and the length of time it took to suture the stitches made my waist unsatisfactory. However, all the efforts were worth it as the cow made a good recovery.
Back in December, we were alerted by a veterinarian at a local animal hospital that an aborted 5-month-old calf with an enlarged head had tested positive on the Schmallenberg test.
This early diagnosis of the fetus could alert farmers to potential problems on the farm this spring with malformations and subsequent difficult births. This study highlights the importance of submitting aborted fetuses from both sheep and cattle at the time of development, as we do not know what disease may be lurking in the background.
Despite this positive result before spring, there is nothing that can be done to prevent further clinical symptoms in spring. A vaccine was produced after the 2013 outbreak, but is currently not available.
Over the past decade, it has been found that the virus occurs in waves as the immunity of previously infected animals weakens. Trying to minimize midge activity will help prevent the spread of disease. During midge season (April to October), avoid grazing near midge environments such as stagnant water or the use of ectoparasites.
Being a new virus since 2012, extensive research has been conducted to understand its pathogenesis. Although this is not currently considered a zoonotic disease, you should always be careful with abortion materials, especially if you are pregnant.
Little did I know when I first started veterinary school that a new virus was on the horizon that would complicate future springs for the foreseeable future.
For now, we don’t know how spring births will be affected. Cases have also been confirmed in Ireland, so you should be on the lookout for cases on your farm this spring and contact your veterinarian for advice if necessary.
The calves are growing well on my home farm, and the calf pen is almost ready, so I feel a little more comfortable in terms of space. I’ll be back in Mitchelstown next week to cover the mid-term break, and I’m looking forward to seeing some interesting cases, perhaps during TB testing.