The first step of antibiotic stewardship, and animal husbandry, is an accurate case definition that allows you to be sure of the disease you are dealing with. Only then can we say that we are correctly applying therapies, including antibiotics, to the problem.
The term “case definition” can sound pretty academic, but you use this approach every time you decide an animal has pneumonia, bloat, pinkeye, acidosis or foot rot. You may have not written down your case definition — but if you are responsible for training or guiding others, you should.
A great example of the importance of an accurate case definition is the difference between infectious pododermatitis (foot rot) and papillomatous digital dermatitis (hairy heel wart). Dairy producers are well-acquainted with hairy heel wart and readily recognize the different stages. In beef production circles, this may be a much newer disease to some.
One of the first things often noticed is a difference in treatment response. Where early cases of foot rot respond to a variety of injectable therapies, hairy heel wart does not resolve after treatment with many of these.
The tricky thing about hairy heel wart is that it can have the classic presentation of a raised, red sore (also called strawberry foot rot), with elongated hairs close by; or it can consist of more flattened sores, with skin erosions that reach from the heel, between the hooves, and up onto the front of the foot above the hooves. It is common to see erosions of some type on the heel — usually very red and sore.
Another difference in the case definition between foot rot and hairy heel wart is how the cattle stand (see top photo). With the typical foot rot lesion between the hooves, the animal tends to gingerly touch the entire foot on the ground; hold the entire foot up; or only briefly place weight on it during walking, but with the foot flat.
In contrast, you will see cattle with hairy heel wart standing with weight on the foot, but with only the toe on the ground. The heel is usually the most irritated and sore.
Hairy heel wart has made it into some open feedlots and bedding pack barns, and outbreaks may be very frustrating. First encounters can leave one wondering why the foot rot cases aren’t responding to therapy anymore.
Hairy heel wart can be successfully treated, but just as in foot rot, the speed of recovery and ability to recover is correlated with how early in the disease process the animal is identified and treated.
Good case definitions also involve a thorough examination of the animal. In feedlots, we typically don’t have tilt chutes or similar equipment available, so lifting the feet in the chute with a rope, or even just a visual examination of a cleaned foot while standing, can help in the diagnosis. For both ourselves and those we train, doing this safely for both us and the animal requires some technique and caution.
Control and therapeutic approaches to foot rot and hairy heel wart in beef cattle can be quite different. Planning to recognize the difference between the two diseases, and having a plan for addressing each, is the start of the process.
If you haven’t encountered hairy heel wart in your beef operation, that is good. If you have, hopefully this article stimulates you to ask some more questions of your veterinarian about variations in clinical presentation, and control and treatment practices.
This is just another example where taking the time to plan disease identification for possible diseases in your operation, as well as preparing a complete treatment protocol, pays benefits in early diagnosis and effective therapy of cases. Our goal as veterinarians is to help you avoid having to use your case definitions in the first place.
Apley, DVM, Ph.D., is a professor in clinical sciences at Kansas State University in Manhattan.