One of the more frustrating things in trying to figure out how to deal with some common diseases is that the research and the advice that is given out is often conflicting. There are lots of reasons why it is difficult to get recommendations that are likely to work and easy to do, and it doesn’t reduce the frustration that some things just do not work well on every farm.
Lameness due to digital dermatitis (DD) is an ongoing challenge on most dairy farms. Farmers are always looking for ways to treat cows that already have it and to find better ways to keep cows from getting lame in the first place. Treatment is an individual cow issue but prevention involves the entire herd. Every freestall barn, not tie-stall barn, should have a footbath. Prevention usually relies on the use of footbaths and any discussion of footbaths brings up a bunch of questions: What to put in it, where to put it, how often should it be used, when should it be changed, can the footbath solution have any risks for people or the environment?
Faculty at the veterinary school in Calgary recently published a report on what research trials show us about managing DD. They focused on evidence that footbaths were effective for treatment of prevention. They also looked to see whether different ways of using footbaths made a difference in how well they worked. As part of this report, the researchers looked at how research trials were designed and carried out. Not all research trials are well designed and, even if they are well designed, they may not be completed as intended. It is also possible that the researchers may not have reported the trial clearly enough for people reading it to understand what to do. All these would influence the amount of confidence you’d have in trial results.
Of course, this type of analysis is only possible when there are enough research studies that can be compared. With a disease like DD, there have been many trials published. The team from Calgary looked at studies that had been published up until March of last year.
The researchers from Calgary concluded that there was little evidence to conclude that the footbaths studied can prevent DD. There was evidence that copper sulfate at 5 % or higher was effective as a treatment. What is most surprising is the lack of research evidence for the benefits of using foot baths.
In trying to explain why the research trials didn’t show a benefit from using footbaths, the researchers dug deeper into how footbaths had been used. They pointed out that the current recommendations are that footbaths should be at least 3 m (10 ft.) long, about 0.6 m (2 ft.) wide and 0.28 m (11 in) deep. Only one of the research trials used a footbath that long. The other trials either used a shorter footbath or didn’t report the size of the footbath. That could be why the trials didn’t show a benefit.
Another important reason why it could be difficult to show a benefit from footbaths is because the bath solution was not changed often enough. The current recommendation is to change solutions (and clean the footbath) after a maximum of 300 cows. Generally, the published research trials changed solutions at least within that recommendation but two trials did not report how many cows went through the footbath. Knowing how many cows go through the footbath is important in figuring out if the results of a research trial might work on actual farms too. If the trial ran unrealistically too few cows through the footbath, the footbath might work in the trial but not be effective on working dairy farms.
So, after looking at the research, veterinarians and dairy farmers are left still with lots of questions about how well footbaths work.
Dr. Robert Tremblay is a veterinarian for Boehringer-Ingelheim and lives near Guelph.