LAMENESS IN BEEF CATTLE (EMPHASIS ON COW/CALF AND FEEDLOT CONDITIONS) J. K. Shearer, DVM, MS University of Florida

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1 LAMENESS IN BEEF CATTLE (EMPHASIS ON COW/CALF AND FEEDLOT CONDITIONS) J. K. Shearer, DVM, MS University of Florida Dr. Shearer is Professor and Dairy Extension Veterinarian with the University of Florida s College of Veterinary Medicine. He is responsible for Veterinary Extension Programs dealing with dairy cattle health and management. He also serves as a consultant to dairy operations and the allied dairy industry both nationally and internationally. His primary research interests are lameness of cattle, effects of heat stress on production and health, and bovine behavior and animal welfare. He is the immediate past chair, of the American Association of Bovine Practitioner s (AABP) Bovine Lameness Committee and currently serves as coordinator of the AABP Bovine Lameness Seminar. Dr. Shearer is presently chair of the AABP Animal Welfare Committee and a member of the board of directors of the Professional Animal Auditor Certification Organization (PAACO). Dr. Shearer is a past recipient of the Florida Distinguished Extension Service Award, the UF/IFAS Superior Accomplishment Award, the USDA Secretary of Agriculture s Honor Award for outstanding innovation in animal health, the AABP Award of Excellence and honored by The Ohio State University s College of Veterinary Medicine with the Distinguished Alumnus Award. It s great to be here and have a chance to share some experiences and observations on foot care with you. As some of you know, I m a dairy guy, but in Florida I see a fair number of foot problems at least in the cow-calf situation and I will share some of those experiences with you. Finally, I have a small cow-calf herd of about 30 cows which also contributes to my range of experience on foot problems in beef cattle. One area I ve been trying to get a better feel for is lameness problems in feedlot cattle. Of course there is a lot of expertise in this room and a lot of folks here who have written on beef cattle lameness in the feedlot and cow-calf situation. So, it is great to be here. Before I get into my presentation, I want to take a moment to make you all aware of a new poster on lameness in beef cattle prepared by Zinpro Corporation. It contains a series of excellent photos on common foot problems. This is a great teaching tool and it s also available in Spanish. For starters, I would like to take a moment to discuss some basic concepts about weight-bearing dynamics in cattle. It s pertinent to everything we want to look at in terms of foot problems in cattle. Ninety percent of lameness is in the foot. Of that occurring in the foot, ninety percent occurs in rear feet with 70-90% occurring in the outside claw. In other words, claw disorders are predominately associated with the outside claw in beef and dairy cattle. There is a very good reason for this, and I want to take a few moments to explore this very important characteristic of lameness in cattle. The dairy industry has tended to rely on nutritionists to solve most of its lameness problems. But, when you look at the 90%-90%-90% pattern of lameness in cattle, it is clear to see that it s more complicated than how we feed cows. If nutritional errors that cause rumen acidosis, and thus laminitis, were the predominant cause of lameness, then 83

2 we shouldn t see that kind of a pattern of lameness in cattle. When an animal is affected with laminitis, the corium of all claws is affected not just the corium of the outside claws of rear feet. In fact, as I ll point later, there is good reason to question whether nutrition and feeding errors are a predominant cause of the laminitis type problems or lesions we typically encounter. For the next short while, I will share with you the work of Toussaint Raven of the Netherlands. When we look at the foot, we see that the outside claw on the left is a larger claw and it tends to have a more flat or stable weight-bearing surface compared to the inside claw which tends to be smaller and have a more sloped weight-bearing surface. A dairy cow housed on concrete has a very flat sole which is different than our cow-calf situation where the sole is sloped toward the center or axial area. Because the wall is hard, and grows faster, the weight bearing surface of the cow s claw on an earthen surface will naturally slope toward the center of the claw. When cows are housed on a concrete or hard surface, they tend to wear their sole and wall down to the point that the weight bearing surface becomes flat. In the figure, we see the larger outside claw and a much more stable weightbearing surface as compared to the inside claw which is smaller with a more sloped weight-bearing surface. The significance of this is that when the cow puts her food down, because of the disparity in terms of stability of the two claws, the weight actually rolls over from the less stable inside claw to the more stable outer claw. The point is, because of the anatomical difference between the two claws, the outer claw bears more weight and as a consequence, tends to have more problems. More sole ulcers, more white line disease, more thin sole-related disorders, and more toe abscess problems because of the weight-bearing dynamics associated with the anatomical difference between the two claws. The weight-bearing surface of the outside claw is very stable. Very little of the axial wall on the inside claw is stable compared to the outside claw. T. Raven, Cattle Footcare and Claw Trimming, When we look at the way the weight shifts through the pelvis we see that when a cow is standing squarely on its feet, she bears equivalent amounts of weight on the inside 84

3 and outside claw, the same as we do. Naturally, when we stand on a hard surface (such as when we are talking with someone) we distribute weight across the soles of our foot evenly, because it s more comfortable that way. But, when we take a step, or if we move or lean one way or another, because of the relatively rigid anatomical nature of the pelvis as a ball and socket joint, we distribute more weight initially to the outside part of our foot, or in the case of the cow, to the wall. The inside portion of our foot or the inside claws of the cow s foot tend to remain relatively stable in terms of the weight bearing or load. Those are two reasons we tend to have more problems associated with outside claws in cattle. These are important concepts for understanding the pathogenesis of claw disorders in cattle Thirty five years ago in veterinary school I remember my professors in veterinary school said that 90% of lameness was in the foot, 90% in rear feet, and 90% in the outside claw. Until the work of Toussaint Raven, we didn t really understand why this was the pattern of lameness in cattle. When we view a cow on pasture, a very forgiving surface, all of these loadbearing effects are dampened by the nature of this forgiving surface, so there s much less transfer of these weight-bearing forces back into the foot. However, when we put the cow on concrete the weight bearing forces are directed back into the foot. There is no give with concrete. Cattle in confinement, like dairy cattle living in a free-stall barn may have significant problems as a consequence of the weight bearing dynamics of the foot on a hard surface. The weight-bearing forces are directed back up into the cow s foot causing irritation in the foot, and particularly the part of the foot that forms the horn of the sole, the corium. The same way that your corium accelerates skin formation on the soles of your foot (on the balls of your foot, on the outside part of your foot, on the heel), those areas where you bear weight, the cow forms more claw horn. As a consequence, excessive weight bearing that leads to irritation of the corium accelerates hoof horn formation. That leads to an increase in overloading especially on the outside claw. In some cases, it s the excess weight bearing that contributes to overgrowth and disproportionate weight bearing. In other situations where the weight-bearing surface may be excessively abrasive, the problem may be excessive wear. In the claw horn overgrowth circumstance, the cow will adapt by assuming a cowhocked posture in order to become more comfortable. By rotating her feet outward and her hocks inward, she is able to displace more weight on the inside claw. Thus, a cowhocked appearance in cattle, and in particularly in dairy cattle, is a consequence of the cow s adaptation to overgrowth of the outer claw. 85

4 T. Raven, Cattle Footcare and Claw Trimming, It is not uncommon for hoof trimmers who work in Europe to determine the need for trimming by observing cows for the cow-hocked posture. This is a very different way of looking at this problem and certainly a different way than most of us have thought about looking at hoof trimming. So, why do we trim hooves? It s to correct the overgrowth that leads to disproportionate weight bearing and potentially disease. The longer the cow bears excessive weight on the outside claw, the more likely she is to develop a problem and particularly when this condition is exacerbated by a disease such as laminitis. Anatomy of the foot I want to talk about laminitis, ulcers, white line disease and those things that we tend to refer to in most situations as abscesses and I want us to understand the differences between these conditions. Knowing what these conditions and their pathogenesis gives us important clues to dealing with them. In the following illustration, number 1 is the wall. The wall grows down from the coronary corium which is just below the skin horn junction (also known as the coronet). It grows down over the claw just like your fingernail grows up from the base of your nail. It grows at about a quarter of an inch per month. Number 2 is the sole and it grows straight down from the solar corium at about an eighth of an inch per month. Number 4 is the corium or dermis (within the claw capsule we usually refer to it as the corium). Number 3 is the white line, that structure that joins the softer horn of the sole with the harder horn of the wall. The white line contains the softest horn within the claw capsule. As such it represents a weak spot in terms of the weight bearing surface of this cow s foot and a place that is not uncommon for us to have problems. Number 7 is the deep flexor tendon and number 6 is the digital cushion. There is no digital cushion in the toe, but in the heel it functions to permit movement of the flexor tuberosity of P3. The pedal bone, or more correctly the third phalanx is contained completely within the claw capsule. The second phalanx or P 2 is proximal to P3, and proximal to P2 is P 1. Number 8 is the distal interphalangeal joint and 9 is the navicular bone. Number 10 is the navicular bursa. It contains synovial fluid and serves to allow the deep flexor tendon to slide over the navicular bone when the cow extends or flexes her claw. In deep digital sepsis conditions, we may see involvement of the distal and on occasion proximal interphalangeal joints. Above the navicular bone and behind P2 is the retroarticular space. It is not uncommon to find abscesses to form in this area, most often secondary to a complicated sole ulcer. Damage to the corium and digital cushion leads 86

5 frequently leads to osteitis or osteomyelitis of P 3 and ultimately detachment of the deep flexor tendon from P3. The infection tends to set up a huge abscess in the retroarticular space. It s important to understand those because our surgical approaches to those will be different than for infectious conditions of the distal or proximal interphalangeal joints. Laminitis The video I am sharing is from a very good dairy operation in Florida that developed a rather serious problem with laminitis in its heifers. The cause was a feeding situation that created rumen acidosis and was secondarily complicated by heat stress. In the video you see a calf with severe laminitis and a stilted gait, very sore feet. The severe pain is even more evident as the calf steps onto the concrete. Note how it begins to switch its tail because of the pain from walking on the hard concrete surface. Acute laminitis gives us a camped-under posture and an arched back. Affected animals are very tender-footed and reluctant to walk. This photo is of one animal two weeks into her lactation that I was able to photograph before she was loaded and moved to slaughter. It is not uncommon to see this condition in first calf heifers and usually within the first 30 days or so of lactation. Oftentimes we ll find these animals standing cross-legged. That means one of two things: in some cases they have laminitis; in others they have a problem involving the inside claw. By crossing their front feet they are able to equalize or in some cases remove the majority of weight from the inside claws. It s an important sign for us to notice. These postures are very important in cattle. Normally in the front foot the cow tends to bear a little more weight on the inside claw. Laminitis is a very important disease. It causes damage to the suspensory apparatus of the claw (that part of the claw that suspends P3 within the claw capsule). This is the part that becomes damaged in the development of laminitis. We also get an acceleration of claw horn growth because of a release of non-specific claw horn growth factors that are part of the connective tissue that are released under this particular circumstance that also contribute to altered weight-bearing within and between claws. We also get the formation of reduced or less-durable horn. This becomes particularly important in situations where animals are exposed to hard and/or abrasive surfaces and have long distances to walk. We see similar situations in the stocker cattle situation and occasionally in the feedyard. 87

6 Looking at a cross-section there is a widening of the distance between the bone and the wall itself and if you look at that you can also see that P 3 has started to rotate. P 3 is sinking within the claw as a consequence of a breakdown of the suspensory apparatus that essentially suspends this bone within the claw. All hoofstock are suspended within their claws; that is they hang in their claws. The suspensory apparatus is constructed by a very strong collagen-fiber bundle system that suspends P 3 within the claw. These fibers are attached to the surface of the bone and interdigitates with the epithelium or the horn of the wall. That is in part what suspends this cow within her hoof. The supporting tissues are beneath with the digital cushion and the dermis (or corium) that produces the horn of the sole. When the cow develops laminitis we get sinking of P 3 because of damage to the suspensory apparatus and the elongation or weakening of this dermal segment. We then get a sinking of the bone within the claw, then compression and damage of the tissues beneath. We also get acceleration of horn growth that leads to weight-bearing disturbances. We also know that laminitis is really a lesion associated with disrupted blood flow within the corium. We get disrupted blood flow, reduced keratinization of claw horn and damage within the lower layers of the epithelium that have real complications later on terms of claw horn hardness. Taking a cross-section through the claw at this region, you have the bone, the digital cushion and the connective tissue (a highly vascular region of the corium). The black line that separates the wall of the sole or the horn of the sole from the corium is the basement membrane. The basal cell layer lies adjacent to the basement membrane on the epithelial side. It may be thought of as the separation between the corium and the epidermis. Bone Connective Tissue/Fat associated with the digital cushion Highly vascular portion of the corium immediately adjacent to the basement membrane Dermal-epidermal junction Epidermis or Horn of the claw The epidermis of the horn is avascular, but the lower layers are living cells by virtue of the diffusion of nutrients across the basement membrane into the lower layers of 88

7 the epithelium. Nutrients diffuse into the stratus spinosum and thus the cells reached by these nutrients are living cells. What s important is that the basal cells have an absolute requirement for the diffusion of nutrients because those cells are differentiating into keratinocytes which will make them become claw horn cells. Some cells within the basal layer will remain as basal cells, others will differentiate. This process has an absolute requirement for the diffusion of nutrients and is negatively affected by any effect on blood flow within the corium. Because laminitis is a disease that s results in an interruption of blood flow to the corium it has grave consequences for proper development of horn cells. As we get laminitis develops we get venous constriction, intravascular coagulation, death of corium tissues and ultimately, a separation (or in the case of cattle, some believe an elongation and weakening of the dermal segment that allows P 3 to sink). Blood flow and the flow of nutrients across the basement membrane into these lower horn cells is greatly reduced. We end up with cells that do not keratinize properly. These cells are weaker and have a poorer resistance to mechanical and physical forces. In other words, we end up with claw horn that is very soft and wears rapidly. The hoofase enzyme I ve shared with you the classical picture of laminitis as we understand it with respect to the weakening of the collagen fiber bundles in the corium that allows sinking of P 3, but some recent work says that there may be something else going on. Researchers from the U.K. suggest that within the corium of heifers in particular, and cows as well, a novel enzyme may be responsible for initiating a cascade of events leading to laxity of the suspensory apparatus. As animals are nearing parturition or calving that they develop high levels of an enzyme that for lack of a better term they ve called hoofase. Hoofase has the ability to activate metalloproteinase enzymes responsible for the breakdown of the collagen fiber bundles of the suspensory apparatus irrespective of whether or not there is rumen acidosis occurring. In other words they re work suggests that rumen acidosis isn t necessary to have laminitis, all you need is hoofase to create laxity of the suspensory apparatus. The U.K. folks have also been looking at weakness of the suspensory apparatus that may be brought about by hormonal changes that occur around calving such as relaxin. Relaxin causes relaxation of the birth canal, but it also has the same effect on the connective tissue within the foot and claw and causes relaxation of the suspensory apparatus which also permits sinking of P 3. In summary, these researchers have found that when they put animals on a very soft surface four weeks prior to calving up to eight weeks after calving, and they compare those with animals kept on a hard surface the entire time, there is a significant difference in the type and number of claw lesions they see between those two groups. By keeping animals on soft surfaces throughout the calving period they have far less, and far less severe, claw lesions. The point is that many people are starting to suggest that maybe nutrition doesn t have much to do with some of the conditions we see. There are other mechanisms involved. Of course, this doesn t explain how a feedlot steer or a bull gets laminitis. But, suffice it to say that laminitis and the laminitis-like syndrome we see is very complex and there is more to it than we have previously thought. 89

8 There s also some work from some from German researchers suggesting that there are changes in the structural characteristics of the insertion zone on P 3 that may be important to understanding the changes we see. Clearly, there is much more we need to learn about this particular disease. From ulcer to abscess We see claw disease, because of the sinking and rotation of the bone within the claw, we see claw disorders. Extreme rotation of the bone within the claw results in compression of the corium in the toe. When this occurs we are likely to get a toe ulcer. The corium becomes so compressed in the toe that it eventually quits forming normal horn. By the time we see it, it s a toe abscess. The more common lesion in dairy cattle is a sole ulcer. Ulcers differ or are defined by the location in which they occur. Sole ulcers occur directly under the flexor tuberosity of P 3. In this location when P3 sinks the corium in this region is continually hammered by the constant weight-bearing on a hard surface and the sinking of P 3. Eventually the cow develops an ulcer. The way we deal with this is balance the weight-bearing between them. Get rid of the excessive horn overgrowth and with our sharpest knife, remove all of the loose and damaged horn. Try not to make it bleed or damage the tissue. Put a hoof block on the healthy claw to relieve weight-bearing. That does two things relieves the pain and also promotes recovery. Foot blocks are a critical part of our treatment in claw disorders. We don t need any antibiotics (topical or otherwise) because it is not an infectious lesion, it s a lesion causes by the sinking of P3 and mechanical forces. It s the sinking of the P 3, the compression of the corium. We can relieve it by altering the weight-bearing. Studies from Cornell and elsewhere have shown no benefit to wrapping and treating ulcers. Dairy farms tend to over-treat these and nearly everybody wraps them, but it s not necessary. In fact it s detrimental in many cases. I agree that it looks like it needs a wrap and a bandage because that makes it look prettier, but in the long run, it s not effective and probably contributes to problems. Understanding the pathogenesis of this particular condition is important. I don t see a lot of ulcers in beef cattle, cow-calf situations or even feedlots. My experience is that these are relatively rare in cattle on pasture. I see them much more frequently as a consequence of housing on hard surfaces. When they become complicated the infection tends to extend upward through the corium into the digital cushion. From there the infection may extend to the navicular bone, navicular bursa, and retroarticular space. Then we end up with a great big abscess in the heel. The whole claw is generally swollen but the majority of these are not in the joint. You can amputate the claw or you can open this up in the back and just expose that whole area, resect the lower portion of the deep flexor tendon and debride the abscess capsule. There s a couple of ways of doing that. I think the better way is to open it up and leave the claw on. If it was a feedlot steer, I might just amputate it. It s quicker and probably better. For long term in a cow I want to keep or a bull, I might go the route of trying to preserve this particular claw. White line disease This has several predisposing causes. There is a natural predisposition of the white line to this problem because of mechanical impact, where it is located on the abaxial part of the 90

9 claw. Weakening by laminitis is very important. Nutrition and metabolism may be involved as well. The vasculature of this area is easily disturbed and there are a number of things that can contribute to this. We tend to see white line disease as a common disorder in situations where we have a significant amount of laminitis occurring. When you have poor horn quality, it not only affects the wall and the sole but it also affects the single softest part of the horn within the claw capsule which is the white line. Between the horn leaflets we have the soft horn of the white line. The only thing that gives it mechanical rigidity and resistance to mechanical forces is keratinized horn cells. It does not contain tubular horn. When cows develop laminitis they get very poor keratinization so they have very weak claw horn. As a consequence you get separation of the white line, material and debris works itself up into white line and ultimately extends to the corium where it creates an abscess. When we talk about abscesses it s not very useful for me to be looking at a set of records on a dairy farm and the records read as: abscess, abscess, abscess, foot wart, and abscess. What I need to know is, is the lesion an ulcer or white line disease? When I have this information I have something that gives me direction in identifying the underlying causes of the problem. As we look at some of these conditions in feedlot situations, we find that many are really white line disease. Some are quite complicated by the time we see them. Toe abscesses are common but the original defect or problem was white line disease or trauma of the sole at the toe. Claw Trimming First of all, in Holstein cows we never trim the toe back shorter than three inches because if we do we are quite likely to trim the sole to thin. When the toe is shorter than 3 inches in a mature Holstein cow we know that the sole is incredibly thin. A major problem in large dairies is excessive claw wear. This is also a problem in stocker and beef cattle where they must walk long distances to graze. So, the basic pathogenesis between dairy and beef cattle is different. Thin soles is one of the worst and hardest problems to fix. I tend to find more thinning on the outside claw in rear feet. In some extreme cases, depending on how cows are eating at the feed bunk, you can sometimes get extreme thinning of the outside claw in the front feet even though there is normally more weight borne on the inside claw. When we encounter thin soles we have often develop problems later in the toe. This occurs because the weight-bearing axis within this foot is pushed forward 91

10 abnormally. This is what we re seeing in the dairies and they always break through at, or near, the white line in the toe. They develop a big toe abscess beneath the sole. Its not the typical pathogenesis of the toe ulcer or white line disease, but it s the extreme thinning of the sole at the toe that leads to a defect in the sole in this region. This is why we look so hard at rubber installation in a lot of our dairies to try to control some of this excessive wear and of course the cows tell us they like it. They like rubber because it is soft. Cows are land animals of course and not conditioned to life on concrete. General impressions Here are some observations from our feedyard experience in Kansas. First of all, feedlots have good facilities for working cattle but poor facilities for working on feet. It s really tough to work on feet in feedyards. By comparison, dairies have poor facilities for working cattle, but good facilities for working on feet. At times, it seems as though dairy farmers have forgotten they are still working with cattle. I tell them they need to go to a feedyard and figure out how to set up their cattle handling facilities. They may not need to go to the feedyard extremes, but something close to that because so many times our facilities for working cattle in dairy farms are inadequate. Foot care facilities are more common on dairies because lameness has become such an important health problem. Foot care equipment Three things I find to be very important that feedlots need to do a better job with foot care: restraint facilities (a tilt table or stand-up type chute), equipment to do foot care (knives, nippers, grinders, etc.) and treatment supplies (foot blocks, etc.) and thirdly, personnel with knowledge and ability to properly treat and manage foot conditions. There is a real opportunity for us as veterinarians to continue to work with folks in the dairy and feedlot industry. Hospital crews need to know how to fix feet problems. Depending on the dairy, I find that some of the best hoof trimmers in the country, possibly in the world, work on dairy farms because they do it every day all day long and many of them have learned by attending a foot care program. In other words, they didn t learn by just watching someone else, they actually learned from someone who could help them understand something about the pathogenesis of foot problems and appropriate care. I don t know what is practical in a feedyard situation. How much can we do? That is the question I still have. I do know that it is quite difficult to work on feet in the feedlot environment and I wonder if we had a little bit better facilities, could we do a better job? Corrective trimming I want to share with you some of the principles of corrective trimming. Corrective trimming is fixing foot problems. What I think is most important in feedyards is fixing feet. You don t need to worry so much about trimming feet, obviously, but we need to fix feet correctly. On dairy farms or in beef cow operations or with bulls, trimming is a more important consideration. The principles of fixing feet are simple. Number one is: remove all loose and damaged or dead horn without causing injury to the corium. In other words, don t make it bleed. I don t like to see a lot of blood around the chute when a trimmer is working. 92

11 When I do, my concern is that we have a person who does not respect the foot and is damaging normal tissue. That has to be corrected. The second thing you have to do with claw disorders is adjust the weight-bearing. That relives the pain and allows the problem to begin recovery. For example we have a white line disease, what we want to do is go in and remove the wall next to this lesion. We want to remove the adjacent wall because with it in place it causes pain. Take it down, lower the heel and make it lower than the opposite claw. Slope the lesion to the outside but don t dig holes in the sole that will allow the impaction of manure and dirt. Slope it abaxially and lower the heel, then put a block on the healthy claw. That s what we re trying to accomplish. When we have a sole ulcer, we want to slope the lesion to axially. Lower the heel and put the weight on the toe and healthy claw. In most cases I would also apply a block. One block should be sufficient. When the block wears down or comes off after three to four weeks, since I have lowered the heel weight will be distributed to the healthy claw. This will provide an additional three or four or more weeks of no weight-bearing on that tissue. That s what the cow needs for complete recovery. Corrective trimming of the sole ulcer involves trimming of loose tissue, lowering the heel and putting on a block. When you do this and don t cause additional damage to the corium, these cows respond rapidly. The corium starts to produce new horn detectable in 2-3 weeks. Recording Claw Lesions By knowing what these lesions are we can utilize the international system for recording claw lesions. For example, if you had a lesion in zone 4, it would be a sole ulcer. If you had a lesion in zones 1, 2 or 3, it would be a white line lesion. This is the international system of recording claw lesions in cattle. To know if it s an ulcer or white line disease is useful information. At the very least it is helpful in understanding some of the work you ll read in the literature on these conditions. Numbered Claw and Foot Diagrams (Greenough & Weaver, 7th International Symposium in Rebilt) Considerations of claw blocks I think that claw blocks are absolutely one of the most important things we use in fixing feet problems. When working with animals on pasture wood blocks are preferable to plastic blocks since plastic blocks tend to wear slower and can cause problems after a while. As the claw grows it pushes the block forward which causes the back part of the block to wear down. If we use a wood block the hope is that by the time it needs to come 93

12 off, it s going to be either worn off or will hopefully fall off. The other option is to go ahead and just plan to come back in and recheck it at some point. The most important things in putting on a block are heel support and the plane of the weight-bearing surface. Also, keep glue away from the heel and the interdigital area but align the inner part of the block with the inside wall. If you don t, the cow s foot will tend to roll over axially. When you keep it proper relationship with the axial wall, the cow will stand very stable on it. The example here is a toe problem. The cow has been shifting her weight backward which has led to the weakening of her flexor tendons. In this particular case, it s especially important that the block be toward the back part of the claw in order to provide support for the heel. Generally speaking, we try to keep the back portion of the block even with the back side of the heel in order to give the cow proper heel support. I m not as concerned about support of the toe, I need the support in the heel. In the photo here, the block is where it should be. That s a very important part of putting on blocks. With the inside wall make sure it s back far enough and think about the housing system that this animal might be on with respect to using these blocks. I suggest that maybe wood blocks will work better for you in some cases since most beef animals are on earthen surfaces. Equipment There are several types of restraint chutes. I like tables because when a cow is on a table she gives up. She realizes she s caught. Two Austrian studies suggest that bovines are less stressed on tilt tables as compared with standup type chutes. I think the table provides better restraint for most feedyard cattle conditions. Question: In Angus bulls and other breeds there seems to be a lot of corkscrew claw-type problems. Is this genetic? Shearer: That is true in many breeds. Angus has their share of this problem. Is it genetic? Yes, I believe it is certainly in part, but there are also contributions from housing and environmental conditions. We know there is a malalignment between P 2 and P 3 that causes P 3 to more or less sit somewhat on an angle. That s why the wall tends to grown underneath the sole. If you trim down the sole, particularly near the toe, it s not uncommon to expose the corium on the abaxial wall at the toe. You have to be very careful as you re trimming these down since atrophy of the inside claw increases the 94

13 potential for problems when you attempt to balance the weight bearing surfaces. Corkscrew tends to affect the outside claw of the back foot and inside claw of the front foot. Question: Could you comment on your favorite type glue to use for blocks? Shearer: I think all the adhesives work very nicely and all the blocks on the market seem to be very good depending upon the considerations for housing on concrete or earthen surfaces. A hard or soft wood block works best in most beef cattle situations. Some people use plastic blockes. The main problem with blocks such as Cowslips or Easyblock is that they may not fit very large claws. In terms of the adhesives, they all work very well except in cold weather. In cold weather conditions, they can all be a little more complicated to work with since they will set up slower. There are a number of ways around this situation. For example, some people keep their glues in a hot water bath or keep blocks under a heat lamp. Keeping them warm makes the adhesive set up very rapidly. Another popular glue these days is Bovi-bond. It works well and has some advantages relative to convenience. Question: In some of the feedyards you ve gone to, can you comment on where you think some of the risk factors might be to exacerbate these types of lameness based on the way we work cattle or the disposition of cattle? Where can we prevent a lot of these conditions from manifesting? Shearer: A very good question - disposition is certainly an important part of this problem. The very excitable, very nervous calf is the one that is more likely to develop toe abscess-type problems. The other part of that problem relates to working facilities, the flooring systems and alleyways leading to the chute are very important. The combination of an excitable calf and a rough flooring system will definitely contribute to toe problems. All that has been cited by a lot of folks over the years that have a lot of experience with this is that excitable cattle tend to be the ones that have the toe problems. It is a tough problem to deal with. All you can really do is manage facilities and flooring and maybe consider using rubber in critical areas. There are many types of non-skid rubber you can put in alleyways. It is a good idea to examine floors and grind down concrete if it gets too rough. Question: The smoother the concrete is sometimes the worse it is. Shearer: That s an interesting thought and I can understand that. There tends to be a lot more slipping and sliding. Question: It s the very smooth and the very rough concrete that create these toe abrasions, and the wild cattle. When we have the toe abrasions which then, once the white line is destroyed and infection occurs, and many times that infection ascends up the leg and we ll find pockets it is in the coxofemoral region and they surprise you. My question is, do you know of any work that has been done where we might block the other 95

14 claw and establish some pain relief or do you think with that type of lesion and burn that it is a hopeless case and they need to be railed? Shearer: I would like to try that on a number of these and see if we couldn t turn some of them around. The other thing with some of the toe abscesses is that a lot of times most of the ones, in fact the ones I want to show you, what I see is tremendous undermining of the entire sole and a large part of the wall. I m afraid that if we only nip off, for instance the toe, what happens is we still have all this other underlying tissue that is separated under the wall or sole and is probably not adequate in those situations. However, to do what I am suggesting requires good restraint of the foot and good foot care equipment. A sharp knife and grinder makes this type of work faster and easier. Most of these do not benefit from antibiotics at this stage. Once you start to get soft tissue involvement above the claw, then that s a different story. By the time you see that, you re well on your way to the involvement of deeper tissues including the bone, retroarticular space and/or the distal interphalangeal joint. When this happens, these animals become chronics. What I m wondering is that if we could take a little more time to remove all loose and damaged horn associated with these lesions, maybe we could have better outcomes? Question: Is there any evidence that laminitis may play a role in some of these cases where we see them as trauma, lacerations, etc. but is there some laminitis that occurs in transit that we re not cognizant of that may predispose groups of cattle? Shearer: A mechanical form of laminitis, right? I think it s possible. It has been written about, particularly from New Zealand and Australia in herds of cows that are walking long distances. I think there are very good possibilities for some mechanical forms of laminitis that may be part of it as well as the feeding and heat stress-related complications. Heat stress causes rumen acidosis because when a cow is heat-stressed she stands around and pants and doesn t eat consistently as she might otherwise. Thus, she doesn t chew her cud and doesn t buffer her rumen. Feedlot and dairy cattle are frequently on the edge of rumen acidosis anyhow, so heat stress is an important contributor to these problems. So, laminitis has got to be a much more important consideration during times of heat stress. It would be nice to see some records that probably would show us that in some of the feedyards where they are keeping good records on foot problems. Predominant Causes of Lameness in Beef Cattle Foot-related lameness: Foot Rot Vertical (Sand cracks) and Horizontal Wall Cracks Digital Sepsis Conditions Distal and proximal interphalangeal joint sepsis Retro-articular space abscesses Traumatic foot lesions Buller injuries Musculoskeletal injuries (broken bones, joint and ligament injury) Lacerations 96

15 Digital and Interdigital Dermatitis and Heel Horn Erosion Infectious arthritis M. bovis Laminitis, white line disease, and toe, sole and heel ulcers Fescue Foot Conformational defects Corkscrew claw Abnormally straight hocks or post-legged postures Upper Leg Injuries: Fractures Ligament, tendon and muscle injuries Nerve injuries Infectious and non-infectious arthritis conditions It s important to identify lames early and establish an accurate diagnosis. It requires good restraint systems. Foot work is hard work and no one feels like they are adequately compensated for their efforts when they do it. In practice, I hated foot work because I didn t have a good way to work on feet. For me, it was a lariat over a barn beam and fighting all the way. It s not a fun job if you don t have good places to work on animals. Secondly, I never knew how to sharpen a knife. I just learned how to do it correctly in the last years. That s also an impediment and very important. And learning how to use grinders can be a real asset. We need to make sure our hospital crews know what they are doing when it comes to foot care. They need training and must continue to learn as much as they can about foot problems. Because it s critical we institute the appropriate treatment on these things. With the exception of foot rot as I mentioned before, most foot problems aren t improved with systemic antibiotics. Fact is, it requires a sharp hoof knife, nipper and usually a grinder, unfortunately. That s the bad thing about it. Corrective trimming and foot blocks are far more than antibiotics. I think we veterinarians have several important roles. We may be treating a lot of these disorders, evaluating lames and cripples and providing advice on treatment or marketing these animals if possible. We also need to be advising people on when it s time to say when, in other words, we need to be sure that some of these chronics are railed sooner or euthanized. Failure to do so is an animal welfare problem. We provide important oversight of hospital crews to see how they are doing and if they have all the equipment they need. We need to answer there questions and monitor records for trends that may suggest a need for change. There are a lot of roles for us as veterinarians. We all have important roles when it comes to the foot problems. Foot rot Interdigital phlegmon characterized by pain and swelling of the foot. In most cases there will be a lesion in the interdigital area and a lot of swelling. The swelling is usually sufficient to cause a significant separation of the toes. I don t think it s too critical what drug you use to treat these as long as you get them early. If you get them late it doesn t really matter what you treat them with either. A good outcome will be in jeopardy when treatment is instituted late. Some of these will become complicated and one of the most common complications of foot rot is infection of the distal interphalangeal joint. This leaves us very few options: amputation or ankylosis of the joint. I m not sure how well 97

16 that works in the feedlot situation. It would be a good study. There is a more extreme form of foot rot called super foot rot. It s characterized by an extremely severe interdigital lesion, lameness that progresses very rapidly and a condition that seems to be unusually resistant to common therapy. Fusobacterium organisms have the ability to become quite resistant to various types of antibiotic therapies. That can be a real problem when attempting to control this disease. Lesions of the wall A common problem in cow-calf situations are vertical wall fissures or sand cracks. The incidence is as high as 64% in beef as compared with less than 1-2% in dairy cattle. So, there appears to be a definite breed or genetic to this problem. Greater than 80% occur on the front outer claw. That s where they tend to be most severe. Some suggest that the horn of the wall is less resilient there and that may be part of the problem. Most of these do not cause a lot of lameness, but when they do they can be very difficult to deal with. The precise etiology is really not well-known. There are many factors believed to play a role. Paul Greenough from Saskatchewan, Canada is the world s authority on sand cracks and has written the most on this particular subject. As I indicated earlier, breed is one of the predisposing causes. Age (older animals tend to have more and accumulate them over time), excess body condition, angle of the dorsal wall (the dorsal wall of front feet is steeper).we tend to have greater weight load on front claws and that may be part of the issue as well. Trace mineral deficiencies, desiccation or drying and some work suggesting that excess selenium may contribute to the problem as well. These do cause lameness at times. Often it is because the edges of the wall will cause pinching of the underlying corium. Trimming away all the loose and damage horn in these cracks prevents the pinching and potential for abscess formation. The primary way for abscesses to occur in claws is for areas of the corium, containing loose horn, to be covered creating an anaerobic environoment. It s loose, necrotic horn that traps or makes the anaerobic environment in claw lesions that creates abscesses. When you remove all of the loose horn you eliminates the possibility of an abscess to form. That s why the most important thing to do with these is to trim them out. As you look at the foot there can also be curving of the inside claw which can suggest there is something wrong with the foot. We tend to find a little bit of a curve on this inside claw in the front foot naturally as a consequence of feeding at a feedbunk. It can be an extreme condition in both beef and dairy cattle. When the cow reaches for feed at the bunk, she increases weight bearing on the inside claw which encourages overgrowth and curving of the claw. So, many of the corkscrew type claws you see in the inside claw of beef and dairy cattle are really an acquired defect from eating at a feed bunk. The side-by-side posture of the front feet is an abnormal posture for the cow s feet. As you know, when she is at pasture she eats with her head between the two legs with one foot forward and one behind. It s important to recognize that the housing conditions we create may cause a lot of the abnormalities we see in feet. Question: Is the curvature a cause or an effect of the claws? Shearer: The work of Toussaint Raven suggests that the curvature of the front claws is an acquired condition. 98

17 Treatment options Treatment options for wall cracks with no lameness or pain, do nothing. On the other hand, if severe enough pare a v-shape channel down to the depth of the crack until you get rid of all of the dark material. You can also make a T above and below the crack, to stop it from going the entire length of the wall. There are some optional treatments such as stabilizing them with wire in the case of real wide defects. Filling the defect with methylmethacrolate causes a lot of heat that it s hard to do without causing damage to the underlying corium. I like to put a block on especially those where the cow may be uncomfortable. We want the corium to start producing horn so it can heal. Why they don t get better is because a lot of times you have permanent damage to the coronary corium that forms the horn. They will never be able to completely repair or recover. Your objective is managing these so they are not painful and don t become a more complicated lesion. If you have vertical wall cracks, thin the horn around the protruding corium and if you have really severe ones, remove the granulation tissue. Sometimes slaughter is the only thing you can do because they are very difficult to manage. As corium protrudes through the wall, you trim it back and it keeps coming back so it gets to be a really difficult thing to manage. I would always trim those back to the level of the corium. The axial wall lesions are really tough. Sometimes axial wall ulcers will occur with these. They are very painful and the cow continues to hammer on those. The vertical wall cracks can be a real problem; fortunately, it s a minimum number of cases that will go that way. Horizontal wall cracks are common in both beef and dairy cattle. Some are associated with calving or physiological changes. Her body decided it was more important to produce milk for the calf than it was to produce hoof horn. That s basically the change she s going through. As a consequence there is an actual delay in horn formation, so you get a horizontal crack that distinguishes this event. When it gets more severe, it may be in some cases associated with another complication in addition to calving. The way we deal with this is very painful for this animal because of the flap that occurs. So, I m just trimming it away and taking that down and you can put a block on that side if it s very painful. But, you must take it all the way down until you get rid of the loose and damaged horn around it. If it s really painful you can put a block on the other claw. For all of those who do this, the easiest way to anesthetize the foot is a tourniquet and the butterfly, stab it in quickly and remove it slowly until you are into the middle of the vein. Then put about ccs of lidocaine intravenously. It makes the task of trimming on very painful claw lesions much easier. When you have more severe forms of horizontal wall cracks, you get what some call a thimble. These can be very painful because they can actually break with the fractured end becoming quite movable. When this happens they are very painful. Treatment is to remove the loose end and use a block on the other claw if it is stable enough. It s not just the wall crack that occurs with calving, but you ll also see these same grooves on the cow s horn. They don t tell you the age of the cow, they tell you how many calves she has had. That same horizontal wall crack you get on the wall associated 99

18 with calving, is the same one you get on the horn. So, in this example there are nine grooves on the horn indicating that this cow has had nine calves. Calving is a totally normal physiological event so these grooves are not indicative in all cases of disease or an abnormal stress. Calves display these lines on the walls of their claws as a response to weaning. This cow has had 9 calves. Roadtrip to Kansas In cooperation with Drs. Brad White and Brian Lubbers we had a trip out to Kansas. Dr. Max Irsik and I went out to see some of the problems in feedlots. We wanted to look at foot-care facilities, equipment and practices in these operations. What we did was work with a trimmer and fitter in Junction City who brought his chute out so we could work on some of these feet. We had a variety of things and I have mentioned some of them earlier. The question that remains for me is this: I have a lot to learn on this but I wonder if there is a way to do more on fixing foot problems in feedlots. Toe ulcers or abscesses can be caused by laminitis and we talked about that syndrome before. Excessive wear, excitable cattle, facilities and flooring are important. Over-trimming can be a cause of that where we are trimming feet as well sometimes. I want you to see that when we get this toe problem it is separation at or near the white line. It s not an uncommon kind of a disorder to have. To put a block on the outside claw does a lot to relieve pain and improve locomotion. Sometimes toe abscesses are hard to see because the only evidence of a problem is lameness and a pinpoint black spot in the white line. I think one of thing that is really helpful is to be able to pinpoint these lesions then drain the abscess and remove all of the undermined sole. In some cases the cause is trauma. These may be distinguished from wear problems by looking for evidence of trauma. What we try to do is take them down with a grinder to the level of the corium. Get the hook of the knife underneath and make sure nothing is undermined and at that point put a block on the other claw. Get the weight off of it and these can heal nicely unless P3 is involved. Some of these are difficult to deal with because they are so painful, but I think we can help by applying blocks. The reason they become so bad is because the lesion is usually through the white line and the tip of the toe and these infection frequently extends into P3. Now you have an osteitis which complicates things. These are pain and often lead to a pathological 100

19 fracture of P3. The secret to success in treating these is removal of all necrotic tissue including bone. Interdigital dermatitis and heel erosions Digital dermatitis (hairy heel warts) is a real problem in some feedyards. There is no good way to handle it that I know of. We have the same problem in dairy heifers and it s extremely difficult to manage. To date, there are only three ways to manage it: foot bathe these animals if they are accessible, wrap with topical antibiotic preparations such as tetracycline or lincomycin, or in some cases, use a topical spray. When they are chronic they become difficult problems to deal with in feedyards as well as dairy heifer lots. In terms of individual treatment, I like to apply a topical antibiotic and bandage them with Co-flex. It is important to not wrap them too tight. The bandages should come off in 3-4 days. Especially in dairies it s not very beneficial beyond hours. In some of your situations it may be beneficial a little longer but I wouldn t want to try to keep them on much longer than 3-4 days. After that the bandage becomes a liability. Claw amputation is a good procedure. But, it should be reserved in my opinion for septic joint conditions. A recent study on ankylosis suggested that arthrodesis might be a better approach in terms of longevity for cows. In a cow-calf situation or in cases with a good breeding bull, ankylosis may be a better option, but in the feedyard situation amputation is may be more acceptable since longevity is less of an issue. Take Home Messages The objectives in foot care and treatment: Identify lames early Establish an accurate diagnosis Foot work requires good foot restraint systems Proper foot care equipment (sharp knives, grinders?) Requires knowledgeable hospital crews (feedlots) Institute the appropriate treatment With exception of foot rot, most foot problems aren t improved with systemic antibiotics Corrective trimming and foot blocks are more important QUESTIONS Question: Where do you buy your felt sharpening wheels? Shearer: I get them from McMaster Carr see the Vendor list below. There are a couple different densities. I get the hard density felt wheel. It s a great way to sharpen a knife. It s great for sharpening necropsy and hoof knives also. The website on how to sharpen knives from Dee Griffin is a great reference. 101

20 The Master Hoof Care Technician Program MASTER HOOF CARE VENDOR LIST Vendor information is listed here for the convenience of program participants. It is in no way meant to imply an endorsement of these products by either the course instructors or the Universities of Florida or Tennessee.