CALVES TREATED for pneumonia may remain vulnerable to further bacterial attack long after antibiotics have stopped working, claims Pfizer Animal Health vet adviser, Carolyn Hogan.

Speaking at Smithfield, she said there was a critical window of bacterial challenge susceptibility that may have a direct effect on treatment success and animals relapsing after treatment.

When pneumonia occurred, it was often the viruses that came in first and were known to cause lung and airway cell damage, she said. “During that period, cells are trying to repair and the calf is more susceptible to bacteria entering the lung and causing further damage.”

Between the time antibiotics have stopped working and the calf’s own defences return to normal, there is increased risk that these bacteria can establish and cause severe disease. Ms Hogan warned that these relapses meant the calf often had to be treated repeatedly and ran the risk of becoming a chronic poor doer.

“Ideally, continue the course of antibiotics through this risk period,” she advised. One option for treatment is Pfizer’s long-acting antibiotic Draxxin, launched this spring.

“A single shot of Draxxin can produce action against common bacterial causes of pneumonia in the lungs for nine to 15 days.” Studies showed this reduced the level of re-treatments by more than 75%, resulting in less set-back and greater weight gain 28 days after treatment, she added.