Dealing with lame cattle Dr. Chris Clark | Back to Vet Advice
Whenever and wherever it occurs, dealing with lame cattle is a pain. It can also be extremely costly when it occurs in an outbreak or affects the bull at breeding time.
Most producers will use the term "foot-rot" to describe every case of lameness and while foot-rot is common it certainly does not account for all lame cattle. This is important to understand because foot-rot is actually the easiest form of lameness to treat; what's more, foot-rot vaccines are available. The problem is that other forms of lameness will not respond to a typical foot-rot treatment and a foot-rot vaccine will not protect you from other forms of lameness.
This may seem incredibly simple but every year I get asked the same questions by producers who want to know how to stop their cows getting "foot-rot." A few simple questions are all it takes to realize that these producers have a lameness problem and do not have a foot-rot problem at all.
What is foot-rot?
True foot-rot is a bacterial infection of the entire foot. It always starts with a wound to the skin between the two hooves which allows the bacteria to access the soft tissues resulting in infection.
The bacterium involved is called Fusibacterium necrophorum. This bacterium is present in soil and manure and cattle are exposed to it every time their foot hits the ground. However, the bacterium cannot penetrate the skin on its own; it needs a wound to get established. Once bacteria reach the soft tissues they reproduce rapidly resulting in severe inflammation of the foot. This inflammation results in the obvious lameness but there are other signs as well (some more obvious than others).
Firstly, the foot should be obviously swollen; more precisely, the swelling should be centered on the space between the two claws, actually forcing the claws apart. The swelling should also be symmetrical and affect both claws. This type of swelling is absolutely typical for foot-rot. If facilities exist for a more detailed examination the foot will be hot to the touch, reddened and if you examine the area between the claws there will be a characteristic necrotic wound between the claws. The tissue of the wound is typically a yellow grey color and the smell of putrefying flesh is also obvious.
Since foot-rot is a simple bacterial infection it responds well to almost any antibiotic. You need to ensure adequate antibiotic levels for two to three days, so my personal preference is a long-acting oxytetracycline (although you do need to consider the withdrawal period if using such a product). If the animal is destined for slaughter in a short period of time Excenel will also work but is much more expensive.
The key thing to remember about foot-rot is that the animal should show a marked improvement in less than 36 hours. If the animal is not improving it is highly unlikely that the animal actually has foot-rot.
The organism causing foot-rot does not develop antibiotic resistance so the need for a more potent or newer antibiotic does not exist. Treating an animal once with antibiotics is probably the best field test to see if the animal has foot-rot or not. If the animal gets better it probably had foot rot! Foot-rot rarely results in complications; in most cases the infection remains confined to the tissues between the claws. In some cases that are not treated early enough the infection can spread from the tissues between the claws to the joints of the foot.
This is a huge problem: infection of the joints (septic arthritis) is a terrible condition to treat. It is hard to get antibiotics to penetrate the joint in sufficient quantities and the presence of infection in a joint results in rapid damage to the cartilage. This means that even if you can clear the infection from the joint the cartilage damage means that the animal will have arthritis for the rest of her life.
The most cost-effective method of dealing with a cow with an infected joint is to have the toe amputated. This can be performed by a veterinarian with relative ease in the field and most cows go on to have a productive life and can survive many years on just one toe.
Other common causes of lameness
Another common cause of lameness is sole abscesses. Most are due to bacteria penetrating the sole of the hoof and reaching the quick. While most producers blame abscesses on the cow stepping on a nail or a stone, the majority are due to an inherent weakness in the foot. The horn of the wall grows from the coronary band down to the sole. The horn of the sole grows down directly from the quick; the point where the horn of the wall and sole meet is termed the "white line." This is the weakest point of the sole and can be eroded by debris and wet conditions. The white line may be further weakened in animals that have foundered after being exposed to a high grain diet.
Abscesses cause a great deal of pain, but there is typically no swelling. The pain is due to the pressure produced by the abscess being trapped between the bone of the foot and the sole. Antibiotics are of limited use as the abscess itself has limited blood supply so they penetrate the area poorly. The only way to treat it is to drain it. Abscesses that are not drained will continue to grow in size to the point where they can affect the entire sole. This results in extreme pain and the possibility of spread to other structures such as the joint. When the abscess is drained it is not uncommon for the entire sole to have to be removed, resulting in a very long recovery time.
We all know that sandcracks are common in beef cattle (surveys in Western Canada have found a prevalence of 20 per cent in older beef cows). However, it is our experience that they are rarely associated with lameness. In some cases a large amount of debris may become impacted in the sandcrack putting pressure of the quick. In other cases the sandcrack may extend all the way through the hoof capsule reaching the quick which can result in an abscess forming. In either case the most appropriate treatment is to trim the sandcrack out with a knife or burr to relieve the pressure.
In summary, foot-rot is easy to identify because of the symmetrical swelling. If a case of suspected foot-rot fails to respond to antibiotics, using a different antibiotic is almost never effective. Instead, if at all possible, the best course of action is to examine the foot and to determine if an abscess is present and, if so, drain it.
Chris Clark is an assistant professor at the Western College of Veterinary Medicine.
