Investigating dairy lameness

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Getting to the root of lameness problems includes looking at nutrition, foot shape, weight-bearing dynamics, flooring, infectious disease, cow comfort and stockmanship issues.

Editor’s note: First of two parts on dairy lameness.

Lameness is one of the major events that can dramatically lower production and shorten the productive life of a cow on the dairy. Nigel Cook, BVSc, University of Wisconsin, says the average cost of a case of lameness is around $180, and the cost for an average Wisconsin dairy is $12,400 per 100 cows per year.

“Work from the United Kingdom shows that an average lameness event reduces milk production by 792 pounds per lactation, or about 3 pounds milk per day,” says Cook. “There is little data on reduced dry matter intake (DMI), but we do know that moderately lame cows have fewer meals per day than normal cows and spend less time eating in free-stall barns. This puts them at an increased risk of consuming larger than normal meal sizes. That is a major factor triggering subacute ruminal acidosis (SARA), which brings us back to the concept of ‘get lame, stay lame,’ which we  have to break.”

Dale Moore, DVM, MPVM, PhD, University of California, believes there is enough evidence in the literature to indicate that lameness affects DMI, which in turn affects production, heat detection (which affects reproduction) and “all combined, leads to early culling from the herd.”

But nutrition or irregular eating patterns can’t take all the blame. “As a student, I was told 90 percent of lameness was in the foot, 90 percent of those were in the rear feet and 90 percent of those were in the outside claw,” says Jan Shearer, DVM, MS, University of Florida. “That pattern of lameness in a dairy cow makes you conclude that there are other factors responsible for lameness besides feeding and nutritional errors that contribute to rumen acidosis. An acidosis situation causes laminitis and affects all four claws, so there should be a normal, natural distribution to all four feet of lameness if laminitis was the cause of most of the lameness we see. Lameness is a far more complex problem than just how you feed cows.”

Moore believes that producers and veterinarians are increasingly recognizing the multifactorial nature of lameness on the dairy. “Cow comfort, footing and nutrition are all involved in the manifestations of lameness in dairy cattle.”

A survey by Clarkson, et al, published in the Veterinary Record, June 1996, studied 37 farms in England and Wales. Thousands of cows were involved over several years of data collection. The range of lameness incidence over a 12-month period varied tremendously but on average was about 55 cases per 100 cows. At any one point in time, prevalence was more than 20 percent of cows in these herds, which agrees with work done in Wisconsin. “It says to me that this is a condition where abnormal has essentially become normal for us,”  says Shearer. “We’ve accepted a certain number of lame cows as normal on everyday life on dairy farms.”

When it was broken down further, over 90 percent of the lamenesses were in the foot, and of those in the foot, 92 percent involved rear feet, and of those that affected rear feet, 68 percent affected the outside claw of rear feet. Only 8 percent involved the front feet, and of those, 46 percent affected the inside claw.

“The most interesting thing is that there was no relationship to the feeding program,” says Shearer. “That didn’t make sense to most of us because for years we’ve assumed how we’ve fed cows was a major consequence on whether we had lameness or not. I think the beauty of the study is that it opens our eyes to looking at some other things that I think are very useful in terms of sorting out lameness problems.”

 

Having a tilt table or other facilities to work on feet can make a trimmer and veterinarian’s work easier when dealing with foot care and lameness problems.

Addressing lameness
So why isn’t more emphasis placed on lameness? “Dealing with it is a dirty job, and no one wants to do it,” says Cook. “Veterinarians are reluctant to lift feet because farms do not have the facilities for them, and each cow becomes a real struggle to examine. The average farmers only see the severely lame cows, and these animals are addressed when the hoof trimmer arrives with the chute, which may be several weeks later.” But, by then it’s often too late to correct problems.

“Too few veterinarians work with trimmers to make sure that surgeries are done appropriately and in a timely manner,” Cook adds. “All farms should have facilities to examine lame cows’ feet when they get lame, but many do not.”

One thing different about large western herds is that some producers are purchasing tilt tables or chutes and getting on-farm labor to do some of the trimming. “This represents a good opportunity for veterinarians to provide training in appropriate foot trimming,” says Moore. “However, almost all still have a hoof trimmer on the farm for the lame cows, and actually most have an off-farm trimmer for their dry cow trims and lames.”

For those dairies using footbaths to help control lameness, Cook advises veterinarians to take an active role. “Footbaths are essential for papillomatuous digital dermatitis (PDD) control in large herds. Veterinarians need to be more involved in the chemicals and the concentrations used. Correctly managed, they are highly effective at controlling PDD, and in herds that have a well-managed program, we rarely see an outbreak. However, many use the incorrect concentration of chemicals, and don’t keep the solution fresh enough for it to be effective. Two hundred cow passes is the rule of thumb for maximum use.”

Moore agrees that footbaths need attention. ‘I am unsure about their success rate, but we tend to have fewer complaints of footwarts as a herd problem. Managing footbaths is always a problem unless the job has been designated to someone, and it is a routine.”

     

Jan Shearer, DVM, MS, says research shows the majority of lameness happens in the outside claw of the rear feet.

When investigating lameness, Dale Moore, DVM, MPVM, PhD, says identifying who, what and where the lameness is most prevalent is a good start.

 Nigel Cook, BVSc, says the cost of lameness for an average Wisconsin dairy is $12,400 per 100 cows per year.

Classifying lameness
All lameness is not the same, and being able to pinpoint exactly what the problem is is critical to preventing and managing lameness-causing factors. In Clarkson’s study, Shearer notes that the most common hoof horn lesions were sole ulcers and white line disease (WLD). “Literature from Europe shows that they never refer to hoof horn lesions as abscesses,” says Shearer. “They always refer to them as sole ulcers or white line disease. Whereas in the United States, when veterinarians, hoof trimmers and dairymen talk about a hoof lesion, we tend to talk about it as an abscess. This, however, is not really a diagnosis but a secondary ramification of a complicated sole ulcer or white line disease, which is an important distinction. To some extent, we can sort out the underlying causes, and it helps us in terms of dealing with the problems at a preventive or control level by knowing a little bit more about which of those we are dealing with.”

It’s important, says Cook, to separate the causes or triggers of lameness from the factors that exacerbate lameness once it occurs. The triggers are infection, with PDD the most common; hormonal changes at calving time, which loosen the connection between the pedal bone and the horn capsule of the claw; SARA, which results in the same loosening of the pedal bone; and trauma caused by excessive hoof trimming or excessive wear.

“Digital dermatitis accounts for around 57 percent of all limb treatments for lameness, sole ulcers are second with about 18 percent and white line disease third at 10 percent,” Cook notes. “Toe ulcers are still rare compared to these three but may present as a herd problem where claws are being trimmed excessively or there is excessive hoof wear, usually in our larger free-stall barns.”

Moore adds that in large California dairies, the most common causes of lameness include laminitis leading to sole ulcers and white line disease, and digital dermatitis, but that upper leg injuries are fairly rare.

Investigating lameness
Investigating lameness on a dairy involves key records. Cook suggests locomotion scoring the herd, reviewing the records of hoof trimming for lesion type, then pursuing the risk factors for infectious lesions and claw horn lesions separately.

 

Minnesota work shows that producers tend to underestimate the level of lameness in a herd.

Moore adds that identifying who, what and where the lameness is most prevalent on the dairy is a good start. “Either the producer or herdsman could give me an idea, the lameness or trimming records can point to the answers to these questions and I could do some lameness scoring to assess the prevalence by pen/age group, etc.”

Cook notes that there is no current system that effectively records lameness. “DairyComp 305 may be modified to keep reasonable records, but there is much room for improvement,” he says. “The American Association of Bovine Practitioners has worked to help standardize lesion recognition, but we now have to teach farms how to organize the records. We need to separate off trim records from lame records and remove chronic cows from the count of new cases treated each month. We then have to set up a system where these animals are re-checked to determine clinical cure, for example, an improvement in locomotion score or resolution of the lesion.”

Shearer says if you see animals becoming lame within 10 days to two weeks following trimming that weren’t lame before, there’s evidence of a potential trimming issue. Problems in the toe might occur from over-trimming claws or claws over-worn from rough concrete. “When you can keep track of the nature of these events, I think you can nail it down whether problems might be trimming related, but it takes better records.”

Shearer uses white line disease as an example of how to investigate lameness. The classic picture of WLD more often than not occurs in the heel. But when cows are walking long distances, because the claw is short at the toe, more weight-bearing is pushed toward the toe. This results in WLD in the toe instead of the heel.

“What I need to know in many cases is what area of the white line is actually affected,” says Shearer. “For someone to just list cows with WLD but not list where it’s occurring, I might get the idea that laminitis is a major complication in the herd, but when I look at it in the toe, then I realize part of the problem is probably excessive wear rates or possibly trimming issues. I need to know those kinds of things to sort out the problem.” He adds that ulcers, too, are in part a consequence of laminitis but there are also situations where it’s a cow comfort issue that needs addressing.

Having hoof trimmers keep records of what they are fixing on the table is very useful, as well. Keeping track of every animal with hairy heel warts can allow the veterinarian to examine the problem by stage of lactation. “We might find that the heifers are the ones predominantly affected, so as these animals come into the herd and go through lactation, if we have a good foot bath in place, we see the cases of digital dermatitis decline,” says Shearer.

Moore belives that most producers do not record the lameness events. However, they do look at the reports that the hoof trimmers leave with them, which function as both an invoice and a list of problems they saw on the trimming day. “The trimmers will list the cows that had to be wrapped for footwarts or ulcer and the ones that needed to have a block put on,” she says.

Moore says Minnesota work shows that producers tend to underestimate the level of lameness in a herd. “I do not believe that they get the veterinarian involved in working on lameness issues in many western herds, but I would be happy to be proved wrong. I suppose that when the lame pen gets large, they might ask the question about what the cause was.”

Herds losing cows to non-foot-related lameness is important to know, as well. This indicates possible problems with equipment that could potentially be managed or fixed.

Who’s responsible for keeping track of lameness? Probably everyone who can be. “On a lot of big dairies, if the dairyman or manager don’t get out to look at those animals frequently, the only who actually sees them is the trimmer, whether it’s an outside person or internal person,” says Shearer. “We have to force ourselves as veterinarians, owners or managers to make sure that we keep track of what’s lame and that it gets dealt with.”

Next issue: biomechanics of weight-bearing and management factors.

First lactation heifers at risk
First lactation heifers are the most at-risk animals on the dairy for lameness problems. “Insults are cumulative,” says Nigel Cook, BVSc. “UK work shows that cows becoming lame in their first lactation are at a massively increased risk of becoming lame subsequently. We see more lameness in mature cows and cows in later lactation. This may reflect the importance of SARA as a trigger and the failure for lesions, such as sole ulcers, to heal adequately. Cows stay lame with these types of lesions for a long time.”

Cook adds that these animals are not adequately followed over time. “Half the cows that are lame at any one time may be lame long-term and not identified as such. We are attempting to identify these chronic cows and put them on frequent trim schedules and short lists for culling.”

Jan Shearer, DVM, MS, notes that research from Christoph Lischer of the University of Zurich shows the heifer’s foot is not developed yet in terms of the digital cushion, which will get larger and change in nature as the animal matures. “These first lactation animals need to have maximum cow comfort and care from us to prevent lameness problems. Once they have significant damage caused by laminitis or significant damage to the digital cushion, for the rest of their lives they are highly susceptible to ulcer problems, so that’s a group we need to be very careful with.”



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