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Toe-tip necrosis in cattle still something of a mystery

Early detection critical to treatment

cattle hoof with a bacteria infection

Having no clue as to what’s causing lameness could be your best clue for diagnosing toe-tip necrosis syndrome in the early stages, which is the only time treatment will be effective.

Circumstantial evidence is the key, explains Dr. Murray Jelinski, Alberta Beef chair with the Western College of Veterinary Medicine at the University of Saskatchewan.

Typically, lameness starts to appear within two days to a few weeks after arrival at the feedlot, frequently in excitable cattle. They go lame on one or both hind feet but initially there is no swelling in the hoof area as is typical with almost all other hoof conditions associated with lameness.

It could start as mild lameness, something that might be dismissed as an injury from trucking or handling. The severity increases as the disease progresses with a shortened stride and obvious pain when the toe touches the ground. In severe cases, animals may be three-legged lame.

“The sooner you treat these calves with antibiotic the better because the cure rate for toe-tip necrosis in the early stage is believed to be good. Once infection gets into the bone, the situation is grave because it’s very difficult to successfully treat bone infections,” says Jelinski.

What’s happening is an injury has exposed the white line at the tip of the claw. The white line around the underside of the claw where the sole meets the hoof wall is the most vulnerable part of the hoof.

When bacteria gain entry infection sets up in the corium surrounding the P3 (third phalangeal) bone at the tip of the hoof. The P3 is comparable to the third bone at the end of a human finger and the corium is comparable to the quick on your nail in that it supplies blood and nutrients for horn growth.

“In many cases, unless you pick up the hoof, wash it and look really, really closely with a flashlight, you won’t see the weakness in the white line. That’s why we think the syndrome is so under-reported and misdiagnosed,” Jelinski says.

Even when they knew exactly what they were looking for Jelinski and Dr. Sonia Marti, who is working on a large lameness study at the Lethbridge Research Centre, were only able to confirm the diagnosis on some calves by clipping the tip of the hoof just into the corium to see brownish-black pus seep out.

The procedure is doable in a feedlot with ordinary hoof nippers, however, some care is needed.

“The key is to start slowly because you don’t want to damage the white line and corium if the foot is perfectly fine,” he explains. “Only the very tip of the toe should be nipped. If the animal has toe-tip necrosis, then a small draining tract will be evident, and it will be surrounded by dead-looking tissue. Additional trimming of the dead tissue and placing pressure on the sole often leads to a small amount of bloody brown pus being expressed from the defect.”

Although drainage may help, it’s not a treatment. At this stage, the infection is already in the corium and possibly the P3 bone and your only real option is to have your veterinarian amputate the claw. Be sure to check all of the other toes for the disease before going ahead with the amputation.

Once the P3 dies and starts to rot, swelling will appear as infection moves into surrounding tissues. It generally starts in an outside claw on a back hoof, spreading from the P3 into the second and first bones of that claw, then the other claw and oftentimes into the leg bone. It’s not uncommon for these lame calves to die from embolic pneumonia as the bacteria showers into other parts of the body.

“Invariably these calves are treated for general lameness within the first month of arrival, don’t respond to several treatments, and end up being put down three to four weeks later,” Jelinski says.

From a welfare perspective and to maintain staff morale he urges euthanizing sooner rather than later. It’s depressing to work with lame animals day in and day out when you know they are in pain and there’s nothing you can do about it.

The research

That’s what Jelinski and master’s student Chad Paetsch set out to learn in a study funded by the Beef Cattle Research Council. Several feedlot veterinarians are co-operating by submitting hooves from cattle euthanized because of lameness and other causes to compare differences in hoof structure and hoof wall properties (hardness, elasticity, moisture content).

The prevailing theory is that it’s related to animals coming off pasture into feedlots.

“If you think about how animals use their hind legs to push and shove against each other when moving through loading ramps, alleys and chutes, it’s quite possible that they rasp down the tips of their hooves on the concrete surfaces,” Jelinski explains.

Their findings to date generally support the theory that it’s a shipping- or processing-based condition that starts with mechanical trauma to the toe, but they have seen calves put down as early as four to five days after arrival and the odd time have found toe-tip necrosis in front hooves as well.

“This makes me think it could have started earlier on, maybe loading at the farm or at the market, and that there could be something else involved,” he says.

Toe-tip necrosis isn’t seen in cow-calf operations, but it could be present at a low level that’s going undiagnosed.

They have found an association between bovine viral diarrhea (BVD) and toe-tip necrosis, however, the virus isn’t a necessary component because many cases won’t have BVD present. BVD is known to suppress the immune system, which may explain its involvement in toe-tip necrosis.

Jelinski has received funding from the Alberta Livestock and Meat Agency to carry on with a micronutrient analysis of hoof samples to investigate whether a mineral deficiency in calves and yearlings coming off pasture could be associated with the integrity of the hoof wall and thus predispose the hoof to infection.

Dr. Barry Blakley, WCVM, will be overseeing the analysis at Prairie Diagnostic Services. This will involve upwards of 400 samples, half of which will be hooves from confirmed cases of toe-tip necrosis to compare against samples of healthy hooves as the control.

Jelinski will continue to work with the engineering department to do more mechanical testing of the hoof wall and sole. This work is supported by a grant from Saskatchewan’s Agriculture Development Fund.

Paetsch will be defending his thesis this fall and results from the micronutrient analysis and mechanical testing are expected by the end of the year.

The goal of all these research projects is to develop a strategy to prevent or control toe-tip necrosis syndrome.

For more information, Jelinski can be reached at 306-966-7166.

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