“One cough is enough to start scanning”
A new approach to reducing antimicrobial use for respiratory problems

By Lilian Schaer for Veal Farmers of Ontario

Pre-conditioning and new ways of thinking around early disease detection on-farm could be a gamechanger for reducing antimicrobial use in veal production. That’s according to Dr. Bart Pardon, a professor at Belgium’s Ghent University, who shared his research into the topic with a full house at the 2024 Healthy Calf Conference.

Farmers around the world are facing pressure to reduce the use of antimicrobials in livestock production. That pressure is particularly strong in Europe – but Pardon believes that while this is a short-term challenge for the industry, it will ultimately give way to more sustainable production.

“The prevailing thought in Europe now is that industries that are unable to live without mass medication need to be rethought or abandoned and the veal industry is one that is in the scope of the (European Union) authorities,” he said. “There is no need to panic, however, because there is so much knowledge that we can use that we currently don’t do.”

In the EU, he noted, the veal calf industry is still the biggest livestock user of antimicrobials, despite already making significant strides towards reduction. This was simpler in the beginning when the industry first began cutting back on over-use; now, additional reductions have become harder to realize.

“It was easy to reduce because we were overusing out of habit; now we have to find ways we can abandon group treatment (altogether),” he said, adding that 60 to 70 per cent of the veal industry’s antimicrobial use is linked to respiratory disease.

The Scientific Opinion on Welfare of Calves, commissioned by the European Commission as part of its Farm to Fork Strategy, will be integrated into law and will mean changes – and challenges – to how calves are raised.

Calves will need to be housed in groups of no more than 10 animals after spending at least 24 hours nursing their mothers, for example, with good colostrum management and higher levels of milk feeding. As well, the minimum age for transport will increase from a minimum of 14 days to 28 days.

By comparison, calves in Canada eight days of age and younger under may only be transported once and cannot be shipped to assembly yards or sales barns.

Preconditioning

One tool is preconditioning calves to ensure they are fit for transport, which includes good body weight, sufficient colostrum intake, and vaccination. As well, calves should be clinically healthy with no pneumonia showing on the ultrasound and a Mycoplasma bovis (M. bovis) negative status.

The industry already knows so much about which calves do well, Pardon said, it’s just a matter of doing more to apply that knowledge into practice.

Calves with low body weights, for example, have no spare energy to fight infections, which are exacerbated by the stress of transport. Failure of passive immunity transfer from the dam also increase a calf’s risk of getting sick.

Upon arrival after transport from their farm of origin, about five per cent of calves arrive with clinical signs of M. bovis. Others don’t yet show signs of the disease, but could also be ill, and these animals will have higher odds of developing chronic pneumonia, as well as weighing an average of eight to nine kilograms less at harvest.

Early disease detection

That’s where lung ultrasonography is a game-changer on the farm, noted Pardon. It takes only one to two minutes per calf and is the most reliable way to detect pneumonia before a calf displays clinical signs of disease.

“Early detection and short therapy are better cures, but you have to find calves in the subclinical phase before they start to show visible signs of disease,” he says. “That’s where the lung ultrasound is a golden opportunity. It requires training and dedication but it’s a great tool that can help move the industry forward.”

According to Pardon, about 40 per cent of calves in the European beef and dairy industries have lung consolidation to some degree. If lung consolidation is more than one centimetre, the calf should be treated with an antimicrobial, which will lead to lung re-aeration.

Pardon’s work has shown that sick calves diagnosed with quick thoracic ultrasound (qTUS) and subsequently treated and cured performed the same as healthy calves who never got sick. qTUS scores show that 60 per cent of mild cases self-cure, whereas only 30 to 40 per cent of severe cases generally get better on their own. 

“We can fully cure calves if we do it right and that’s an eye opener,” he said.

Short therapy

There is still the need, however, to find strategies to reduce the volume of antimicrobials used and to move away from group treatment.

That’s where Pardon’s work in adjusting therapy length for each calf individually based on its lung scan or qTUS score rather than treating an entire group of animals is showing remarkable results.

In calves where antimicrobial treatment was stopped after a single injection, 70 to 80 per cent of calves went on to be cured; 95 per cent were cured after a seven-day course of treatment. Overall, qTUS-guided individual treatment showed it is possible to reduce 50 to 65 per cent of antimicrobial use compared to group treatment.

“A calf with mild pneumonia should be cured in four days, moderate pneumonia in six days and severe in eight days although odds for a cure are low in severe cases,” Pardon said, adding that the calves with one centimetre lung consolidation are the ones that can best be helped with this technology.

“One cough is enough to start scanning, that’s your early warning; you can scan them all or do a lung ultrasound on just that one calf,” he said.

Using lung ultrasound does require training so users can take correct measurements, but Pardon believes it’s a great tool with the capacity to change the future of the industry as it allows farmers and vets to definitively state if an animal is healthy or not.

As well, qTUS-guided therapy is opening up news ways for farmers to use antimicrobials by moving away from population-based medicine and instead embracing precision medicine.

“Early detection and short therapy result in a better cure, and by using qTUS and fit for transport criteria, we can make a more sustainable industry,” he believes.