Early treatment of pneumonia in calves important, but prevention even more so
Whether it’s beef calves or calves raised from dairy operations, managing these youngsters’ health is a constant chore for producers. Because these calves have immature immune systems, diseases pop up much more frequently in these animals compared to their older counterparts. Adding to that fundamental challenge are hardships of weather stress and (for some dairy calves) confinement.
Ask producers which disease they most often see in these calves, and you’ll likely get one of two answers: pneumonia or scours (diarrhea).
The most recent U.S. Department of Agriculture animal health surveys bear this out. In dairy calves, more than half of death losses occur from scours, with pneumonia accounting for a quarter of them. Those two problems are the most-often cited reasons for beef calf illnesses and deaths as well.
It’s well-accepted that sick animals caught and treated early in the course of their illnesses have a much better chance of full recovery. Whether it’s giving antibiotics and anti-inflammatories to a calf with pneumonia, or fluids to a scouring calf, early interventions increase the chance calves will get over their ailments.
But do these sick calves ever completely “get over” something like pneumonia?
Checking a calf off as “recovered” from pneumonia usually means the calf’s clinical signs have subsided: no more breathing difficulty, coughing or fever, and the calf’s energy level and alertness have returned to normal. When this happens, we pat ourselves on the back and chalk up another treatment success.
However, for many calves surviving pneumonia, lung damage lingers. In this regard, a case of pneumonia is different than a case of scours. When intestines are damaged by scours germs, they repair themselves. The damaged gut lining grows back, and while the calf has been set back several days, the intestines’ function returns to normal fairly quickly.
Not so with the lungs. When pneumonia strikes, the calf’s immune system responds by pouring in fluid and white blood cells from the bloodstream to the infected section of the lungs. For most pneumonia infections, this process expels the offending bacteria, limiting the spread of the damage.
The calf’s life gets back to normal, but deep in the lungs, the damage often remains. Airways have been destroyed. Blood vessels have been obliterated. Pus is walled off into abscesses and the affected lung turns into meaty scar tissue. The calf is now relegated to a life of walking around with a useless chunk of lung, limiting his oxygen-carrying capacity.
If this healed area of lung damage is fairly small, we might never notice an obvious problem in the calf — but she’s not quite the same anymore. Researchers find that calves that have suffered pneumonia — even those that have seemingly recovered — do not gain weight as well as those that have not.
In addition, dairy calf studies comparing Holstein heifer calves with lung damage to those without find that, when grown, the lung-damaged calves produce significantly less milk during their first lactation.
Both these examples point to how important healthy lungs are to an animal’s productivity. Lung capacity (oxygen-carrying capacity) is necessary to support development of muscle- and milk-producing cells as the calf grows. Additionally, even a small knot of damaged lung tissue serves as a drain on the immune system, sucking away nutrients that should go into growth or milk production.
Detecting and treating these pneumonia cases early in the course of the disease is important in limiting the extent of this lingering damage. This is not as easy as it seems, though. Research projects show that ultrasound can find spots of active pneumonia present in a significant percentage of calves that anyone would classify as completely healthy.
At a recent South Dakota veterinary continuing education meeting, veterinarians were introduced to the use of ultrasound in these calf populations. While logistically challenging for beef calves, this method holds a lot of promise for identifying treatment candidates and on-farm pneumonia risk factors in groups of dairy calves.
Early treatment of pneumonia cases is important, but prevention even more so. Providing a clean, well-ventilated environment for young beef or dairy calves, making sure colostrum management is optimal, and administering a sensible vaccination program with veterinary input are all ways to help ensure those calves meet their true potential later on in life.
Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University.