Lameness is one of the most common reasons for cattle producers to treat a cow with antibiotics.
In my experience, producers assume that most lameness cases are foot rot until proven otherwise. However, treating all cases of lameness with antibiotics can be a significant mistake.
The livestock industry’s use of antibiotics is under more scrutiny, and practising good antibiotic stewardship requires a proper diagnosis before reaching for the bottle of antibiotics.
Arthritis in the last joint in the hoof, called the coffin joint, may mimic many of the signs of foot rot. These cases are often difficult to treat and will not respond to antibiotic therapy.
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As well, administering antibiotics that have a long withdrawal time may eliminate the option to slaughter the animal if the lameness turns out to be something other than foot rot.
Foot rot is caused by local injury of the skin between the claws, followed by a bacterial infection. Softening of the skin by water, feces and urine may predispose the skin between the claws to injuries.
As a result, we often see a spike of foot rot cases in spring during the snow melt or in a spring where there is lots of rainfall.
Traumatic lesions may initiate the bacterial infection. This means cows that have to walk over stony ground or areas with wood or other debris may cause damage to the interdigital skin and allow the bacterial infection to occur.
The clinical signs of foot rot are distinctive, and producers can usually distinguish foot rot cases from other causes of lameness by carefully observing the animal.
Foot rot usually causes a rapid onset of lameness, which is usually localized to one limb. There is uniform swelling of the coronary band, which is the area where the skin meets the top of the hoof.
It is especially important to note that this swelling is uniform and on both sides of the foot.
Cases of arthritis or traumatic lesions often have swelling that concentrates on one side of the foot and are not uniform.
There is also swelling in the interdigital space, and the claws should be slightly separated.
Producers who are able to examine the foot will find splitting of the interdigital skin and foul smelling debris between the claws.
In many cases, these animals will also have an elevated temperature as a result of the interdigital infection.
Cattle with foot rot will usually rapidly respond to antibiotic therapy and will markedly improve within a few days. A lack of response to antibiotic therapy is usually a sign that the cow’s lameness is caused by something other than foot rot.
Producers who have treated an animal for foot rot that does not improve shouldn’t continue treating with antibiotics or try a different antibiotic.
Some other reason is usually causing this animal’s lameness, and antibiotics may not be any benefit in these cases.
Septic arthritis of the coffin joint is one of the common problems that can mimic foot rot. This is often a bacterial infection of the foot, which results in a serious infection of the deeper structures of the foot.
These may result from a complication of sole ulcers, an infected sand crack or traumatic lesion or sole abscesses that may be caused by stepping on a sharp penetrating object.
These animals are often severely lame and may barely touch their foot to the ground. They have swelling around the coronary band, which is often not symmetrical. One claw is often more severely affected.
In severe cases, this swelling may move up higher onto the lower leg. You may occasionally see pus draining from a site on the coronary band.
These cases are often difficult to treat and will not usually respond to only antibiotic therapy.
It is sometimes possible for a veterinarian to amputate the affected claw if only one is affected. Veterinarians can also try other techniques to drain the affected joint.
Salvage slaughter may be the only option if these cases are advanced, but it is not possible if the cow has been given long acting antibiotics because the lameness was assumed to be foot rot.
In these cases, humane euthanasia should be considered if there are no other options for therapy or if recovery is unlikely.
An animal that cannot rise without assistance and is reluctant to walk or exhibits halted movement should not be transported for slaughter. Emergency slaughter on the farm may be the only option.
Animals that can rise or remain standing without assistance but demonstrate obvious signs of lameness should be transported only with special provisions to the nearest suitable place where it can be humanely slaughtered or cared for.
The Canadian Beef Code of Practice lays out the conditions and special provisions for transporting com-promised animals.
