One of the most common ailments that cattle producers will observe in cows or bulls out on summer pasture is lameness. Whether a case is mild or obvious, an animal turning up lame at some point in the summer is inevitable in every operation.
Not every case of lameness observed on pasture is caused by the same set of circumstances. A few causes of lameness, such as deep wounds on the limbs, are quite obvious. Most, of course are not. More frequently, animals are observed limping without any observable external injury. A high percentage of these lameness cases are called foot rot by observers. Sometimes that analysis is correct, sometimes it's not. Why would one want to differentiate true foot rot from other lameness causes?
First off, let's understand what is meant by foot rot. Foot rot refers to a condition more accurately called infectious pododermatitis. It is an active bacterial infection of the skin and deeper tissues between the toes of cattle. The bacteria, usually Fusobacterium necrophorum, are found just about anywhere there's mud, manure, or dirt. It takes some sort of insult to the skin between the toes in order for the bacteria to start causing damage. This most commonly occurs when cattle are standing for prolonged periods of time in water, mud, or manure. However, abrasions that can occur (for example) when cattle walk on bean stubble or on frozen chunks of dirt in the wintertime can also provide a site of entry for the bacteria.
The infection then starts to work on the tissue between the toes. Initially, swelling of the foot directly above the hoof occurs, which may extend up into the pastern or fetlock in severe cases, but not higher. Swelling in a joint without any swelling below that joint isn't due to foot rot; such cases often turn out to be severe sprains or joint infections. As the swelling commences, the animal begins to limp, possibly to the point where she is hardly bearing weight on the affected limb. The skin between the toes breaks open and exposes an open, foul-smelling wound. These characteristics - the swelling right above the hoof and the open smelly wound between the toes - are the hallmarks of a diagnosis of foot rot.
But why is it important to know whether an animal's lameness is due to foot rot or a case of a cow putting her foot in the wrong badger hole at the wrong time? The answer lies in treatment. Foot rot in its early stages is quite responsive to treatment with antibiotics such as long-acting tetracycline or penicillin. Your veterinarian will be the best resource for determining the best treatment for a case of foot rot. Another reason for determining whether a case of lameness is actually foot rot lies in prevention. When more than one case is diagnosed in a group of animals, it behooves the producer to look for the inciting causes, whether it's animals spending too much time in the stockdam, or having to navigate a rocky patch of ground to get to the water tank.
Accurately diagnosing lameness in cattle out on pasture is often a challenge. Because an animal that's limping is an animal in pain, we owe it to them to try to provide relief through appropriate treatment when possible. Restraining an animal in a chute allows one to perform a careful examination of the foot. Early cases of foot rot are obvious by the lesion between the toes. Such examinations are also beneficial because other causes of lameness such as sandcracks, toe abscesses, and penetrating foreign bodies can be detected.
Proper and prompt diagnosis of a case of foot rot provides the animal an excellent chance of recovery with antibiotic treatments. Treating other causes of lameness with antibiotics is often unrewarding. Letting a case of foot rot go untreated means prolonged pain for the animal and a greater chance of the infection settling in a joint and becoming chronic. Contact your veterinarian for advice about how best to approach your lameness cases this summer.