Lameness is the second leading reason (behind bovine respiratory disease) that feedlot cattle are pulled and given antibiotics. Lame cattle eat less, grow more slowly and less efficiently, may be shipped early and often don’t grade as well. These add up to a significant economic cost. When cattle get lame late in the feeding period, pre-slaughter withdrawal times limit the number of antibiotic treatment options. 

A team of Canadian researchers led by Agriculture and Agri-Food Canada’s Karen Schwartzkopf-Genswein recently published a review of large-scale studies of foot-related lameness in feedlot cattle (A Review of Foot Related Lameness in Feedlot Cattle; https://doi.org/10.1139/cjas-2024-0047). 

What they did: These researchers reviewed studies of infectious foot-related lameness (i.e. not including chronic arthritis related to mycoplasma or histophilus) in feedlot cattle. These included several multi-year studies conducted in Canadian feedlots with treatment records on between 10,000 to over 1,000,000 cattle. Important hard-to-find details can appear when researchers have data sets that large. 

What they learned: Foot rot is the most common cause of infectious foot-related lameness in feedlots. It can occur at any point in the feeding period (as well as in cow-calf operations). Foot rot causes swelling between the claws of the hoof (often on the hind limb) that may extend into the lower leg. If the front of the foot is clean, a foot rot lesion often looks dark and is surrounded by jagged edges with sloughing skin. Early detection and treatment are key to preventing a worse infection. Foot rot typically responds to any long-acting antibiotic, so if the initial treatment doesn’t work, it’s probably not foot rot. Several different bacteria appear to be involved, which may be why available foot rot vaccines aren’t effective. Foot rot is most common in poor pen conditions; good drainage and a good bedding mound help reduce the risk. 

• RELATED: ‘Grimace scale’ could help gauge pain, stress in cattle

Digital dermatitis (also known as DD, strawberry foot rot, hairy heel wart) is generally much less common than foot rot in feedlot cattle. Digital dermatitis is more commonly associated with dairy cattle. Digital dermatitis is rarely diagnosed in cow-calf operations but is becoming increasingly common in feedlot cattle. It doesn’t usually appear until cattle have been on feed for three months or more and can occur in combination with foot rot. Affected cattle may not be lame and the affected foot may not be swollen, so these cattle may be harder to find in the pen (and may help explain why it isn’t often seen or diagnosed on cow-calf operations). 

Digital dermatitis starts as a circular or oval strawberry-red lesion where the skin and the heel bulbs meet at the back of the foot. In more advanced or chronic lesions, the infected skin can become rough, scaly and develop long hair-like projections. Digital dermatitis generally responds to topical antibiotics such as tetracycline. Copper sulphate footbaths are less effective for treatment, particularly once they’re contaminated by dirty hooves. Properly disposing of used copper sulphate is also a problem. Digital dermatitis is caused by multiple bacteria, but different bacteria than foot rot. There is no vaccine. Clean, well-drained, well-bedded pen conditions help reduce the risk. Digital dermatitis bacteria can survive in the soil to infect new cattle, so once a feedlot is contaminated it probably becomes a fact of life. 

Toe tip necrosis nearly always occurs in the first days to weeks after cattle arrive at the feedlot. It always occurs in one or both hind limbs. There is no swelling, which distinguishes it from foot rot and trauma. It’s believed to happen when the sole of a hind foot has been scraped thin on rough concrete floors in the auction barn or handling area. The worn sole may then develop a tiny crack where the sole meets the toe of the hoof. This allows debris and bacteria to enter (sort of like a sliver under your fingernail) and set up an infection. It’s more common in excitable cattle, and in groups that are handled aggressively. Early in the disease, the affected cattle tend to be slightly lame and take very short steps. However, if left untreated these animals may become three-legged lame. 

Diagnosis and treatment involve nipping the tip of the toe to confirm the diagnosis, allowing it to drain like an abscess, and giving a long-acting antibiotic. Avoiding the temptation to buy wild cattle at a bargain price, having appropriately (not aggressively) grooved floors in handling areas and low-stress cattle handling are the best preventions. 

Bottom line: Not all lameness is caused by an infection, so not all lame cattle need antibiotics. Not all lameness is foot rot, so there is no one-size-fits-all treatment. It’s a lot easier to make an appropriate treatment decision if you can get a good look at the foot before treating it so that you can be more confident about why it’s lame and how to treat it appropriately. 

What does this mean to you? Low-stress cattle handling and keeping pens as clean and dry as possible aren’t always easy or cheap, but neither is lameness. 

The Beef Cattle Research Council is a not-for-profit industry organization funded by the Canadian Beef Cattle Check-Off. The BCRC partners with Agriculture and Agri-Food Canada, provincial beef industry groups and governments to advance research and technology transfer supporting the Canadian beef industry’s vision to be recognized as a preferred supplier of healthy, high-quality beef, cattle and genetics. Learn more about the BCRC at beefresearch.ca.

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Pain medication may come with adjunct treatment such as antibiotics but sometimes this is unnecessary. When veterinarians prescribe non-steroidal anti-inflammatory drugs (NSAIDs) for pain, they may choose based on label claim, past experience in the field, price per treatment or per 100 lbs., duration of activity, ease of administration, advice of associates or slaughter withdrawal. There are several things to consider but hopefully after reading this article and discussing it with your veterinarian, the decision will be that much easier in the future.

For years the clinic I was associated with would give calves an NSAID called flunixin intravenously after hard calvings. The thinking was that it would reduce swelling and soreness on the legs and potentially the ribs. I believe it did reduce swelling. We also put calves on IV fluids and NSAIDs for scours and it’s now proven that appetite is increased.

Only recently have we looked at the cow. Administering NSAIDs should lead to less obturator paralysis and quicker recovery from vaginal contusions after calving. Appetite is not lost so milk production is maintained. If one follows the Beef Code of Practice, one should use NSAIDs for major surgical procedures such as C-sections at the time of delivery or at the beginning of surgery. I know from experience the recovery after C-sections is much more rapid and the cow doesn’t spend the first day moping around.

I have used injectable products, oral meloxicam and now the Banamine TD, all with great success. The latter two have a greater ease of administration which makes them both desirable for calving cows.

You are unlikely to see many trials on weight gains or the economics of painkillers. In the short term companies want to prove the painkiller cuts a decent percentage of the pain in different scenarios. Common sense tells us that the cattle will do better initially. Health outcomes are likely improved. There usually will be compensatory gain once the animal recovers so if we follow these cattle to slaughter, there will be little difference. The bottom line is that all these painkillers have been proven to take away various types of pain and it simply is right thing to do, in my opinion. Talk to your veterinarian.

With calving, one needs to have parameters based off a hard, medium or light pull. Light is being able to pull by hand with no other assistance. A medium or hard pull is when a calf puller is applied.

One also knows pulling with the cow’s contractions, being slow and methodical and applying lots of lubricant can avert a tough calving. You must recognize your own skill level and treat accordingly. Was there a tear created, did you pull too fast, was the calf slow to get breathing, did you hear any unusual pops or snaps indicating tension? All these are clues the pull may have been too hard.

There are several ways NSAIDs may help a cow after a pull, including better milking, increasing appetite quickly, mothering up, and potentially being quicker to rebreed. Many producers now have painkillers prescribed for the season and have them close to the chute so they can easily be given.

I think most veterinarians would agree with me and probably prescribe something like dexamethasone for a cow that is down after a difficult calving. This steroid is very potent and so takes effect quickly. It’s effective if given early in cows with obturator paralysis. The drawback is its immunosuppressive effects so often antibiotics may be prescribed concurrently.

The other bucket of pain we deal with is lameness in all areas of cattle production. Lameness is prevalent in the feedlot. It is the second-most-frequently treated clinical symptom in feedlots, right behind pneumonia. The newest NSAID on the market, Banamine TD (pour-on), even lists lameness caused by footrot on the label. By using pressure-bearing plates, you can prove the product took a good percentage of the pain away, as the lameness greatly subsides after treatment.

Getting the diagnosis right is the most important thing when dealing with lameness at the feedlot or in other areas of cattle production. This may involve lifting up the foot and having a look. Usually we can avoid using antimicrobials but in almost all cases NSAIDs will be used. Both the Beef Code of Practice and public perception justify doing this. There may be times when an animal with a sprain strain is left to convalesce on its own but that would be rare. The NSAIDs pretty much all have slaughter withdrawals so in heavy feedlot cattle that may be a consideration.

Feedlot cattle sprain strains, footrot, interdigital dermatitis, sole ulcers or toe tip necrosis, arthritis, septic arthritis and broken legs indicate the wide range of lameness producers see. Broken legs usually indicate emergency slaughter, yet all the rest may require NSAIDs. The footrot would require antimicrobials but many of the other conditions would not require systemic antimicrobials.

A large number of bigger feedlots still use a lot of dexamethasone because they have low withdrawal for slaughter and are cheap and potent as an anti-inflammatory. But no work has been done on the painkiller aspect. There is also the question that steroids have an immunosuppressive effect so in many ways the NSAIDs may be the safer proven alternative.

There are additional uses for steroids at the feedlot such as certain pneumonias that cause abortion in heifers. Today most veterinarians will have a solid opinion on which side they stand with steroidal use in our feedlots to manage lameness. Most of the NSAIDs last a couple of days or so, which means that retreatment would be considered only in cases of advanced lameness.

The Beef Code of Practice outlines the use of treatment, convalescence or shipping for salvage regarding lameness. Sometimes cases need to be reassessed, especially with joint infection. If the lameness isn’t improving or the animal isn’t gaining weight, it may need to be either slaughtered on site or put down.

Many other conditions in the feedlot may use NSAIDs as primary or ancillary treatment depending on the feedlot veterinarian’s protocol. Buller cattle, calving difficulties, severe rectal prolapses as well as surgeries such as perineal urethrostomies and exploratory surgery also may require NSAIDs. The common procedures such as dehorning and castrations have been talked about in other articles and there is no question cattle recover quicker and have better health outcomes when they receive NSAIDs. That goes for branding, too.

Any increase in weight gain will be negated as compensatory gain later in the feeding period, but pain control is simply the right thing to do in some situations. Your veterinarian can help decide when it is necessary and what products to use. They will in some cases help cut down the need for antimicrobials.

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Banamine transdermal, a non-steroidal anti-inflammatory drug (NSAID) produced by Merck Animal Health, was released at the end of January. This pour-on product, with flunixin meglumine as the active ingredient, is used to reduce fever related to bovine respiratory disease (BRD). However, it’s the drug’s proven ability to relieve pain related to foot rot that is stirring up interest now that has been included on its label.

“Initially, it came out that it was an anti-pyretic,” says Roy Lewis, a technical services veterinarian with Merck and frequent Canadian Cattlemen contributor. “The biggest application for that in the cattle world would be a calf in a feedlot with pneumonia, let’s say. It’s going to be given an antibiotic of some sort, and then this drug would help pull the fever down, and so that was on the label initially.”

Lewis explains that most pharmaceutical companies that produce an anti-inflammatory drug are now focusing on specific ailments or procedures that cause pain. “That’s what they want to get on the label so that people see that they can use it for that.” In the case of banamine transdermal, Merck used foot rot as a model for lameness.

Merck chose to focus on lameness because it is an issue that affects all types of operations, and it was simple to measure the drug’s effectiveness, says Lewis. For example, for a product to be approved by the United States Food and Drug Administration (FDA), the drug company has to prove that it works. When it comes to proving that an animal’s pain has been lowered, pain needs to be measured in a simple way. As Merck was able to do this, banamine transdermal was approved by the FDA.

• Read more: Ancient scourge remains a problem in modern rations
• Read more: Not all lameness is foot rot

This was achieved by using pressure plates to measure how much weight an animal puts on a specific foot as they walk. After walking lame cattle over a pressure mat to record this and other metrics, the cows were given the drug and then walked over the same mat six hours later. Based on this research, Merck found that the treatment decreased the pain in these animals by measuring the amount of pressure they put on the affected foot.

“It’s pretty easy to measure,” says Lewis, who explains that pain resulting from other ailments and procedures, such as castration, is often harder for researchers to quantify. “We know it’s painful and we know scientifically these drugs should work. Now we just have to prove it.”

While there are a number of different banamine products currently available for cattle, this specific treatment, a translucent red liquid, is applied along an animal’s back from withers to tailhead. It’s advised to apply this to dry, undamaged skin, not rubbing the product into the animal’s skin or hair. Producers need to ensure the animal doesn’t get wet for around six hours, according to the label, though Lewis suggests this length of time may be unnecessary, as it starts to absorb in about 15 minutes.

The drug was developed as a topical application for ease of administration. “As innocuous as it might be to give them a needle, you have to catch them in a chute or have them restrained, and it does in itself create a little bit of pain,” he says. You can apply it easily in an alley or by walking up to the animal if it is quiet enough.

Banamine transdermal comes in a plastic bottle with a graduated dosing chamber. The recommended dose is one ml per 15 kilograms, which Lewis says is a fairly low dosage. “It’s absorbed pretty quick and reaches maximum levels in the body in about two hours.”

The withdrawal time for slaughter is 13 days after the last treatment. As no milk withdrawal has been established, the drug is not yet approved for lactating dairy females.

The label warns that the drug shouldn’t be used on breeding sires “as the reproductive safety has not been evaluated.” Lewis confirms that this caution is due to the fact that there hasn’t been research into this particular area, so the implications are not yet known. “That’s where veterinarians have to use what we call ‘extra-label use’ and use our own best judgment,” he says. “If they know that this bull is lame and it should have this, in my eyes I don’t see any issue with it.”

The label also warns that NSAIDs may have the potential to delay calving, so it is not recommended for use within 48 hours of an expected calving date. As well, administering the drug immediately after calving may interfere with uterine involution and expulsion of foetal membranes resulting in retained placentae. This particular caution is related to the original injectable form of banamine, and Lewis confirms that it is a legitimate concern to consider when choosing a fever or pain reducer. “There is a little bit of higher incidence of retained placentas if it’s used,” he says.

The adverse reactions listed on the label include “transient swelling, erythema, dandruff, broken (or) brittle hair, hair thinning, alopecia or thickening of the skin… at the application site,” which may be due to an overdose.

The label advises that producers wear protective gloves and safety glasses when applying the drug. Lewis notes that while this may make producers worry that it’s particularly dangerous, earlier pour-on products were introduced before more recent safety regulations, and wearing safety glasses and gloves is always a good precaution when using topical treatments.

Banamine transdermal has a low freezing rate and a high flammability rate. The latter makes it safe to use at brandings, as opposed to pour-on products that contain rubbing alcohol. “In fact, I tried to set it on fire and I couldn’t,” says Lewis.

Lewis anticipates that Merck and other drug companies will be looking into new label applications for pain relievers like banamine transdermal. “Following the Beef Code of Practice and what the public is dictating, more and more pain killers are being used. So this drug and probably the other ones that are out there for pain, the companies will be researching more applications for it, like giving it at a hard calving or post-surgical,” he explains. Regardless, a veterinarian can help you decide what kind of pain reliever is best for your situation.

“I think what’s going to happen is over time, veterinarians will have most of the pain killers at their clinic, and they’ll help the producer decide.”

The post New drug targets pain from foot rot in cattle appeared first on Canadian Cattlemen.

“My colleagues and I here at the university have done some work on this, and we’ve looked at the feet of many cattle that have gone to slaughter. The sand cracks almost never penetrate the entire thickness of the hoof wall. They are just in the outer layer. The way the hoof matrix is built, it has what is called a crack diversion mechanism. As the crack penetrates deeper, it is diverted away from going in a straight line.” The pressure is dissipated outward and spread out rather than creating a deep split.

“The animal’s body responds to the presence of a crack by actually thickening the hoof wall in that area, to protect itself. Often the very worst-looking cracks don’t cause lameness. If you cut into a dead hoof and look at it, you might discover that the hoof wall in that area may be up to two to three times thicker than normal. Sometimes, if the wall gets very thick in a localized area, you may also see a bit of remodelling of the bone of the foot, to accommodate the increased thickening of the hoof wall. Some of these cracks can persist for years,” says Clark.

Causes

“We don’t always know why they happen. Actually this question was the basis of my master’s project. We didn’t come up with complete answers, but we did discover that hydration — the water content — of the hoof horn varies considerably throughout the year on the western Canadian prairies. In summer the moisture content of the hoof is fairly close to what I believe would be optimal. Even in dry years the hoof tends to pick up some moisture. But as cattle go through winter here, the hoof dries out,” he explains.

In the cold, dry climate, the feet are not exposed to any free water. There may be a lot of snow, but at very cold temperatures the snow is dry, not wet, and that moisture is not available. There’s no moisture in contact with the foot. “The humidity is very low here, in the winter. We took some hoof samples of cattle in February, when it is typically -30 C. There is snow, but it’s very dry. Those hoof samples were also very dry,” he says.

“As the hoof wall dries out, it starts to desiccate and become brittle. From studies that have been done on horse hooves, we know that as the hoof dries out, it becomes less pliable and more prone to breaking,” says Clark.

“We also discovered that cracks are more common in larger, heavier cows. We believe it has something to do with the physical forces of walking that particularly affect that outside claw on the heavier cattle. They probably have more force and strain on their feet, and if the feet are brittle they become prone to cracking in this particular area. The cracks are almost always at the front of the toe on that outside claw of the front foot. We think it is a local stress in this area that causes the hoof to crack,” he says.

One of the things he looked at was whether longer toes might make the claws more vulnerable to cracking, due to the added strain from the long toe. “We did find that the bigger feet were more prone to cracking, rather than the length of the toe, as the main factor. The volume of the foot was most important,” he says.

“The only thing we’ve ever seen published regarding what you could do to prevent cracking is that there’s some evidence that supplementing the diet with the B vitamin biotin may be beneficial. But that’s the only thing I’ve ever seen that suggests a way of preventing it. On the whole, I think cracks are mainly a consequence of raising cattle in certain environments,” says Clark.

There may be a genetic tendency toward cracking, as well. “One paper looked at this, trying to determine heritability of hoof defects, but this is a tough area to study. The researchers tried to demonstrate a genetic factor but were unable to find a conclusive link. This wasn’t a major study, but the only one I’ve seen,” he says. Some people feel there is a genetic link because often the animals that get hoof cracks in a certain herd are related. It may be due to the inherited conformation of the front feet. Hoof quality/horn strength in horses is definitely affected by genetic factors and this is probably true in cattle.

“I was going through some of the ancient books here in our university library, and found a horse book dating from the 1700s, which had a wonderful description of sand cracks in horses. It discussed the fact that these cracks were caused by keeping horses in dry, sandy areas. This illustrates the fact that after 300 years we really haven’t progressed very much in our understanding of these cracks. We do feel that cracks correlate with dryness in the environment, more than anything else,” says Clark.

“We took whole hoof samples from cows at slaughter houses — cows that did and did not have sand cracks. We did biomechanical testing of the hoof, and were unable to find a difference. There was certainly nothing about those animals’ hooves that seemed to make them more prone to cracking in a fracture mechanics test. The only things we found that made a difference were the position of the claw and the size of the claw. The front outside claw was most commonly affected. Those were the two biggest risk factors we could find, and the fact that the water content of the hoof really dropped off in the winter. There have been other theories proposed regarding causes, but the final conclusion of my master’s thesis was that drying was the biggest risk factor,” says Clark.

“The way the hoof is formed, it’s almost like reinforced concrete. The hoof wall is made up of tiny tubules that run vertically; they are like rebar in concrete. This is why most cracks form vertically rather than horizontally, because that is the natural cleft between the tubules. But the crack diversion mechanism usually makes sure that the crack doesn’t split inward but is diverted off to the side,” he says.

“Once in a while an affected animal does go lame and you may find an abscess at the deepest part of the crack. In my experience, dealing with lame cattle, the crack itself is rarely the cause of lameness. We see many lame cows, and the owner often thinks it’s due to the crack. When we trim the foot out, we often find an abscess somewhere else in the foot, rather than under the sand crack.” Usually an abscess is from a different cause, and the crack is incidental.

Treatment

“Regarding what you can do with sand cracks, our usual advice is the old adage: if it ain’t broke, don’t fix it. If the animal is lame, however, the owner may want to deal with it. You can clean the crack out — such as grind it out or trim it out — and try to get back to healthy horn. I am not convinced that this will absolutely encourage it to grow out and disappear. I think the risk factors for crack formation still exist. Even if you could get that one to clean up, the chances of it reforming would be quite high,” says Clark. The susceptibility of that animal probably hasn’t changed and the likelihood of future cracks is always there.

“I generally don’t worry about cracks unless they cause a problem. The only way you know if sand cracks are a problem is by examining the cow’s foot — to see if she’s sore when you palpate the area over the crack, and the coronary band above the area. If there’s an abscess it will also be hot. Then we use hoof testers, like we use on a horse. If you put pressure over the sand crack and she winces, then we suspect an abscess and we clean it out,” he explains.

Debriding the area and cleaning it out, getting to the abscess and draining it, will relieve the pain and lameness. It’s important to deal with the abscess, just like you would any abscess. “I always tell my students that it’s important to not focus on the sand crack when faced with a lame cow. Look at it like any other foot, and try to find the true cause of the problem — to see if there’s an abscess and where it is. If it happens to be in the sand crack, deal with the sand crack,” he says.

“If there’s an abscess under the crack, we simply open it up and use a very fine grinder to clean it up. We just remove all the damaged and underrun horn and smooth out the sides. In some cases, in the past, I’ve also tried filling the crack with an epoxy product, but I don’t think it really helps in the long run,” says Clark.

The hoof will grow out slowly. “The crack takes a long time to grow out. The hoof grows at a rate of about five millimetres per month. The average foot length is about 7.5 centimetres (3.5 inches) so it takes about 15 months for the wall to grow completely new horn, from the coronary band down to the tip of the toe. It’s a slow process getting it to grow out, and the risk for the crack reforming is quite high in those individuals,” he says.

Prevention

In commercial beef production, hoof cracks really aren’t much of an issue. It’s not economically feasible to deal with them unless they are causing lameness. They might be a cause of concern in a purebred herd, however, when the rancher is selling registered bulls and heifers.

“If someone comes to look at their animals, those breeders don’t want cracked feet. Even in those cases, however, other than telling the cattle breeder to try supplementing the cattle with biotin, I’m not sure what else to suggest — to minimize the cracks. They do seem to be a prairie issue and are not reported as often in other parts of the world. It’s primarily an issue in Alberta, Saskatchewan and Manitoba,” says Clark.

This type of crack is rarely found in dairy cattle and is much more common in beef animals. “Dairy cattle spend their time in a wet environment. Their feet are always exposed to manure and moisture, and don’t dry out,” he says.

The post Don’t fret too much over sand cracks in hooves appeared first on Canadian Cattlemen.

Importance of diagnosis

Lameness may be from a nail in the foot, injury (a pulled tendon or broken bone), an abscess or snakebite. Dr. Eugene Janzen from the faculty of veterinary medicine at the University of Calgary says a common cause of lameness in range cattle is a problem in the hoof such as a hoof crack, an overgrown toe that’s broken off, or even a hoof abscess.

Even though an abscess is an infection, it won’t respond to systemic antibiotics. Abscesses must be opened and drained, to relieve pressure and pain. “Swelling in other areas of the body are not as painful because skin will stretch, but with an abscess in the foot there is bone on one side and hoof horn on the other side, so the pressure is excruciating,” says Clark. “It’s like the pain when we smash a finger or toe and swelling underneath the nail makes it worse. If you’ve ever had an abscess under a fingernail or toenail, you can understand how painful it is for the poor cow. You have to relieve the pressure,” he says.

An abscess is a localized infection, sealed away from blood circulation, and can’t be adequately treated with antibiotic injections. Flushing it out and treating topically is the way to deal with it.

“Foot rot is a different kind of infection. The cow may have stepped on a stone or something sharp that cuts through the skin between her toes. Once the skin is pierced, bacteria in the environment can easily enter, and get into the fat pad between the toes. Fusobacterium necrophorum is everywhere — one of the common bacteria that assist with decay and rotting of dead things,” Clark explains.

“The tissues between the toes actually start to rot. The toes are separated because of the infection and swelling. There will also be symmetrical swelling of tissues above the hoof. It will be hot to the touch and the skin (on a white-legged animal) will be red. The lesion smells like rotting flesh. If you look closely you can see gray-green rotting tissue protruding,” he says.

“It’s easy to look at a lame foot and see whether it’s foot rot. Even from horseback you can get close enough to see the swelling between the toes. If it’s foot rot you can treat with antibiotics and it should get better. If there’s no swelling, it’s not foot rot and treating it will not help. In that situation, you need a closer look at the foot and remove the stone or the nail or deal with the abscess or whatever the pain-causing situation might be,” says Clark.

“The swelling from foot rot is below the fetlock, and just above the hoof,” says Janzen. If the swelling extends above the fetlock joint it’s probably not foot rot.

“Infection in the interdigital cleft may be due to a variety of bacteria ubiquitous in the environment. The common one is Fusobacterium and this is the one for which a vaccine has been created. Other pathogens can be involved as well, and complicate the infection. None of them, however, can produce foot rot on their own without a break in the skin. The people who have tried to reproduce foot rot in experimental trials have all had to scarify the interdigital area,” he says.

“Thus you need two things for foot rot to occur — the ugly bacteria and the injury. In dairy cattle we often see foot rot in what dairy practitioners call ‘new barn syndrome’ which means the cows have more interdigital injuries if the concrete hasn’t been worn off and smoothed yet. If cows are walking on an abrasive surface and also have to walk through a slurry of manure, this becomes a perfect combination for foot rot,” Janzen says.

“The literature about foot rot states that incidence in range cattle is something between one and four per cent but livestock people here in Alberta would probably say it’s higher, depending on the year. Also, if a ranch has cowboys training horses, the owner tells me their foot rot rate is high. The cowboys want roping practice so they catch and treat any cattle that they think might have foot rot — and they may be over-treating.”

On the flip side, some ranchers don’t ride among their cattle often enough to see the ones with foot rot and may not treat them soon enough. Long-standing cases may result in serious complications like joint and tendon sheath infections.

Treatment

“Penicillin will work, but you need to dose it daily. Many other drugs have a foot rot claim on the label, but there’s little point in using something like Nuflor or Micotil because they are more expensive. I use long-acting oxytetracycline, since it is less expensive, and generally one treatment will do it. The only drawback with this drug is that there is a fairly long withdrawal period, so you need to be very certain you are treating foot rot,” he says. You wouldn’t want to discover later that the animal has a broken foot (rather than foot rot) and the best choice would be slaughter.

“If the cow is at home in the yard where you can treat daily, you can use the oxytet that’s not long-lasting, or use trimethoprim sulfate,” says Janzen. “If you are not absolutely sure it’s foot rot, and it might be something else like a broken bone in the foot, and one of your alternatives might have to be slaughter, consider using Ceftiofur since it doesn’t have a withdrawal time, in Canada,” he says.

“For treating range cattle, sustained-action antimicrobials provide coverage for more than one day. It doesn’t matter which one you use but long-acting oxytetracycline is probably the most commonly used. It’s probably best to save the more modern drugs for when oxytet no longer works. Some of our pharmaceutical people have cautioned us about using the sustained-action antimicrobials that are more organ-specific, such as the drugs that concentrate in mammary tissue or the lungs, for instance (for treating things like mastitis or pneumonia). Those would not be our first choice for treating foot rot,” Janzen says.

“If the lameness doesn’t get better after antibiotic treatment, there are only two explanations,” says Clark. “One is that it is not foot rot. It’s an abscess or some other problem. Second, if you let foot rot go too long before treating it, infection can spread from the fat pad between the toes and get into the joints. This is much more serious. Once the infection gets into the joints it starts destroying the cartilage. Even if you can eventually clean up the infection (which is much more difficult once it’s in a joint), you are still dealing with an arthritic joint. That animal will still be lame, and you are faced with either slaughter or possibly amputating the toe — depending on the circumstances. Those are your only choices,” he says.

Janzen says that half the cows sold as culls because of lameness are suffering from complicated cases of foot rot. “It’s very serious if the infection has got into the joint, and even worse if it’s into the tendon sheath because antimicrobials won’t get in there,” says Janzen. There’s no economical way to treat that condition in cattle.

This is why it’s important to catch it early. On a longstanding case of foot rot — in situations where cattle are on large range pastures and you don’t see them every day — it might take two doses of antibiotic to clear up, according to Clark. “But the main thing to keep in mind is that if it’s not starting to improve after the first treatment, you need a closer look at the foot to make sure of what you are dealing with,” he says.

In most cases a producer can make a diagnosis of foot rot, and treat appropriately. “But rather than assuming a lameness is foot rot, figure out why the animal is lame. There are many reasons that an animal could go lame. This is why I am nervous about using dart guns in which an antibiotic can be delivered at long distance. Advertisements for these guns often use foot rot as their example, but if you can’t get close enough to get a good look at the foot, that’s not a good idea!” says Clark.

“In the old days, before we had all these new drugs, we treated foot rot locally with an antiseptic or antimicrobial wrap around the foot,” says Janzen. “I’ve also read about research where people cleaned the interdigital cleft with soap and water. If you did that religiously for four or five days in a row, the foot would heal just as well as it would with antimicrobial treatment. But no one wants to lift up a cow’s leg five days in a row to wash out the foot! Maybe 20 years from now if society says we can’t use antibiotics anymore, we may have to resort to these sorts of treatments again!”

Prevention

Janzen says some ranchers are fencing off water holes and lifting the water with solar pumps to a trough on higher, dry ground. “Then cattle don’t have to go into the water holes to drink. The PFRA in Saskatchewan was instrumental in demonstrating to producers that cattle preferred to drink from the troughs rather than have to wade in the filth and mud.”

There is a foot rot vaccine available. “It’s been in use a long time, but there isn’t a clinical trial that actually demonstrates whether it works or not,” says Clark. “The problem with this vaccine is that in many producers’ minds it is a lameness vaccine. But it is only a foot rot vaccine, and foot rot is not as common as they think, so it’s hard to gauge whether the vaccine has any benefit. In the absence of evidence, I am a little cautious,” says Clark.

Janzen adds, “If foot rot is caused by Fusobacterium necrophorum (the) vaccine will probably be protective, unless the infection is complicated by or caused by Bacterioides spp. In Canada, some producers give their bulls this vaccine when they do their breeding soundness evaluation in the spring,” he says.

“When I was growing up, everyone believed that foot rot could be prevented by feeding organic iodine with the salt. Many ranchers still feed iodized salt, or salt blocks containing iodine, in an effort to prevent foot rot. Whether it prevents foot rot or not, is equivocal. The level at which you’d have to add iodine, or organic iodide, in salt would likely be prohibited by the federal government regulations in Canada. Organic iodine has been withdrawn in Canada for that application,” says Janzen. “You can still put iodine in salt, but at such a low level that it’s hard to tell if it helps.”

The post Not all lameness is foot rot appeared first on Canadian Cattlemen.

There are many different types and causes of lameness, ranging from genetics (e.g. conformation), nutrition (e.g. founder), the environment (e.g. frostbite), injuries and infection (e.g. foot rot, hairy heel wart). Some may have several causes, like toe tip necrosis syndrome (TTNS).

This syndrome always affects the hind claws and usually develops within three weeks of arriving at the feedlot. The disease begins when the white line of the hoof separates. The white line between the sole and hoof wall is thin, and represents an inherent weakness in the hoof. If the white line separates, bacteria can penetrate into the hoof and affect the underlying P3 (coffin) bone at the tip of the toe. Animals that are treated early will probably recover, but successful treatment is unlikely once the P3 bone itself is infected. The extreme lameness that results from untreated (or unsuccessfully treated) TTNS causes a rapid loss in body condition and poor performance. The disease is sporadic, but clusters by truckload and feedlot pen.

Opinions differ on how TTNS gets started. Some think the infection starts on the outside and works its way in. Excitable cattle may damage the soles of their feet while struggling in the chute, allowing bacteria to enter and infect the hoof. Alternatively, perhaps the cattle struggle because their feet are already sore from abrasions on concrete flooring in auction marts or processing facilities, or from standing in the truck for long periods. Others think that TTNS may work its way from the inside out through the hoof, perhaps related to a pre-existing infection in the bloodstream, grain in the feedlot receiving diet, or BVD.

Dr. Murray Jelinski of the University of Saskatchewan and co-workers recently published a study to better understand how TTNS develops (“The lesions of toe tip necrosis in southern Alberta feedlot cattle provide insight into the pathogenesis of the disease;” Canadian Veterinary Journal 56:1134).

What they did: In October and November 2012, three commercial veterinary practices collected hind feet from 67 feeder heifers and steers (averaging 385 to 700 lbs.) that died or were euthanized in commercial feedlots (on average within three weeks of feedlot arrival) and submitted them to the research team. For each TTNS-affected animal, hooves from an unaffected control animal were also collected. At the university, each hoof was sliced lengthwise into thin sections. The location, nature and severity of the lesions were described and compared between TTNS-affected and control hooves.

What they learned: The white line between the hoof and sole had separated in all of the TTNS-affected hooves, but in only three per cent of control hooves. The white line was also significantly thinner in TTNS-affected hooves than in control hooves. In TTNS-affected hooves, tissue in the toe tip was always visibly inflamed, the centre of the toe was inflamed about two-thirds of the time, and the upper section of the toe was only inflamed a quarter of the time. Microscopic examination only found dead (necrotic) tissue in areas that were also inflamed. There were no signs of smaller, isolated infections apart from the toe tip infections. Unlike foundered cattle, the P3 bone was not rotated in TTNS cases.

What it means: TTNS most likely moves from the outside in, not the inside out. This is significant because the prevailing belief is that the disease begins with cattle damaging the soles of the hooves. This leads to thinning and weakening of the white line, and separation of the sole from the hoof wall. As previously noted, once the bacteria breach the white line, they travel into the foot to infect the P3 bone and other soft tissues. The infection doesn’t always end at the foot. Sometimes it spreads up the leg along the tendons and between the muscles, or it may even enter the bloodstream where it spreads to the lungs, liver, and kidneys.

The finding that the disease appears to move into the foot rather than starting at P3 and moving outwards may help us prevent it. Specifically, flooring should provide traction, but must not result in excessive wear. This typically occurs when animals are overcrowded and agitated in the chutes, resulting in hind feet being abraded by concrete flooring as they push against the animals ahead of them. Considering both the flooring and how the animals are being moved and handled may help prevent costly losses.

The Beef Research Cluster is funded by the National Checkoff and Agriculture and Agri-Food Canada with additional contributions from provincial beef industry groups and governments to advance research and technology transfer supporting the Canadian beef industry’s vision to be recognized as a preferred supplier of healthy, high-quality beef, cattle and genetics.

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While there are things being worked on it is not an easy fix. What we have found is there are procedures, vaccines combined with minimizing stress (often easier said than done) that go a long way to reducing its incidence. But when cases do become clinical a decision has to be made early for the welfare of the calf to either treat and ship, or euthanize.

Mycoplasma comes in many clinical forms but in feedlots we mainly see it in respiratory and joint infections.

The respiratory cases are often indistinguishable from other common pneumonias in the feedlot and the joint form can be very similar to histophilus abscesses. In a great number of chronics in our feedlots, if lab specimens were submitted to verify what your veterinarian had diagnosed, mycoplasma would commonly play a role. These cost the feedlot industry millions in treatment and labour as well as deaths and chronics that need to be euthanized.

With mycoplasma we need to concentrate on prevention. Even though a few antibiotics have indications for mycoplasma on the label they are more for metaphylactic treatment when exposure is imminent.

After a few weeks in the feedlot they say pretty much all calves are infected (meaning they have been exposed and are carrying the organism) yet in well-managed yards with pre-immunized and preconditioned calves the incidence can be kept to a minimum.

In cattle, mycoplasma is a secondary invader. In the case of respiratory disease it often comes in on the heels of viral pathogens, primarily IBR. Other respiratory bacteria such as mannheimia, pasteurella or histophilus can also get established and set up the lungs for the invasion of mycoplasma later in the course of the illness.

A good number of these infections may spread to the joints. Once in the joints, especially if more than one joint is involved, the chances of recovery are very slim. It then becomes an animal welfare issue and often lots of money is spent on antibiotics, painkillers and other medications before the decision is made to euthanize.

• More from the Canadian Cattlemen: Lameness in feedlot cattle

In the bison industry, mycoplasma is almost always a primary pathogen and can cause considerable death loss in naïve populations of calves, cows and bulls. There appears to be immunity established once the disease goes through but death losses can get quite high on the initial exposure.

Researchers are working on an effective vaccine and in some cases autogenous vaccines have been tried. That is where the organism is isolated from the farm and used to make a vaccine. This is easier said than done. Often there are commensal mycoplasmas present but not the ones causing the disease. As well, mycoplasma is not like other bacteria in that it has no cell wall, making it more difficult to develop a vaccine.

Several of these vaccines have been tried in the bison industry, some with reasonable success. There is a commercial swine vaccine for mycoplasma so it stands to reason perhaps one may be developed for the cattle industry. But for now it remains the most frustrating pneumonia and joint infection in the feedlot sector.

Researchers at VIDO, the Vaccine and Infectious Disease Organization, are looking at it. This is the organization that came up with the first scours vaccine years ago. They are world-renowned and if we look at how scours vaccines have evolved we can hope mycoplasma vaccines will follow suit.

Antibiotics don’t appear to be the answer. When we treat chronics long term with antibiotics with no hope of eliminating the infection we also raise the possibility of creating resistance to these antimicrobials.

So that leaves us relying on anything that reduces stress and/or reduces the likelihood of other respiratory bugs taking hold. Theoretically, that should reduce the incidence of mycoplasma pneumonia.

We, as veterinarians, always talk about reducing stress. Transportation, processing, weather, parasites and exposure to other cattle cause stress and all play a role in determining whether calves get sick.

Pre-immunization is one precaution cow-calf producers have direct control over and feedlots can then ask for pre-immunized calves. Fortunately this covers the vast majority of calves in Canada. Cow-calf producers are vaccinating calves younger today and reaping the benefits with fewer sick calves on summer pasture. If the boosters are given at weaning then we should, in theory, have less respiratory disease.

We can also avoid unnecessary transportation stress by selling directly to feedlots through satellite or online sales. The distance transported is maybe not as significant as the stress of loading and unloading the calves a couple of times.

Various electrolyte formulations have been tried to minimize shrink during transport. Excessive shrink is a sign of stress.

Controlling parasites increases the gain for cow-calf producers and boosts an animal’s immune response to vaccines.

Taken together all these steps should result in healthier calves with less propensity to get sick when entering feedlots.

And less sickness should translate to less mycoplasma.

In the absence of an industry-saving vaccine or treatment for mycoplasma, we have had to concentrate on prevention, and I think it is working. On average, death losses are decreasing as we prevent more of the other respiratory pathogens, and so is the incidence of mycoplasma. And this trend should expand as we see more collaboration between the cow-calf, trucker, backgrounder and feedlot sectors.

We may never totally eliminate mycoplasma but we can keep it at bay with these prevention strategies.

In light of high calf prices this fall we should all be aiming for the fewest possible cases of mycoplasma in our feedlot population.

Roy Lewis is a Westock, Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.

The post What can we do about mycoplasma? appeared first on Canadian Cattlemen.

The finding, which was part of a larger study in progress led by researchers from the Lethbridge Research Centre and University of Calgary Veterinary Medicine (UCVM), didn’t come as a surprise to veterinarians who work with feedlots because improved medicines for pneumonia in combination with treatment on arrival have substantially reduced the number of respiratory disease cases in fall-placed calves.

It’s easy to see that an animal is lame, but not always as easy to determine what’s causing the problem. Dr. Michael Jelinski of Veterinary Agri-Health Services, Airdrie, Alta., demonstrated this concept in a video quiz to lead off a lameness workshop held at the UCVM annual beef cattle conference this summer.

Narrowing it down to lameness most often seen in fall-placed calves in Western Canada, he says foot rot, mycoplasma arthritis, toe-tip necrosis and, in some feedlots, digital dermatitis are leading causes. Laminitis, injuries and potential ergot poisoning may also be problematic.

• More from the Canadian Cattlemen: The importance of field diagnosis

Foot rot and digital dermatitis

Classic signs are rapid swelling and redness in the soft tissue between the claws usually causing the claws to spread apart. The area feels warm and has a rotten odour if the infection is oozing out. Left unchecked, the swelling will spread up around the hairline at the top of the hoof and back into the dewclaw area up the fetlock.

Typically, the animal will be very lame and avoid putting weight on the affected hoof if at all possible.

“If foot rot is suspected and it doesn’t respond to an antibiotic appropriate for foot rot, then it’s probably not foot rot,” Jelinski says. Unfortunately there are plenty of alternatives causes for lameness.

Digital dermatitis (hairy heel warts) is a highly contagious skin infection that doesn’t respond to injectable antibiotics.The cause is still not clearly understood, but spirochete bacteria along with other bacteria and possibly a virus have been implicated.

Raised lesions appear between the claws and often on the bulbs of the hooves and around the dewclaws. Swelling isn’t common, however, the lesions may occur along with foot rot.

Historically, digital dermatitis has been an issue in dairy barns, but its prevalence has been increasing in Alberta feedlots in recent years.

The standard dairy treatment is to clean the foot and apply a topical antibiotic with a short-term wrap, Jelinski explains. This can be difficult to do in a feedlot. In outbreak situations, feedlots have used footbaths of copper sulphate or formalin with some success.

“Given the increasing prevalence of this disease and the difficulty managing it, it’s important for feedlots to be vigilant with lame cattle that are not responding to treatment for what may appear to be foot rot,” he advises.

Mycoplasma arthritis

Mycoplasma arthritis generally starts as a pneumonia. When animals are under stress with weakened immune systems, mycoplasma bacteria can invade the lungs and from there enter the bloodstream and settle into joints.

Any joint can be affected, but ankle, stifle, hock, and elbow infections are common.

Stifle joint infections caused by mycoplasma arthritis may be mistaken as foot rot, however, animals with a stifle problem will typically stand with the toe on the affected side just touching the ground and the foot won’t be swollen.

Mycoplasma pneumonia can respond to an appropriate antimicrobial given early, but joint infections are difficult to treat. You have to get enough antibiotic into the joint to be effective, especially when there is tissue damage from the infection. Some of these animals will come around with time, but it could be weeks or even months. About one to two per cent of animals in a feed yard will be affected with a joint infection due to mycoplasma and some will require euthanasia, but the numbers vary greatly by feedlot.

Toe-tip necrosis syndrome

One theory is that it sets into the hoof through a weakness at the tip of a claw thought to be caused by wear and tear on the hooves that happens along the way from the farm to the feedlot. Typically, it starts in one or more hind claws, but can affect front claws as well.

Jelinski says some feedlots see it more than others. The big risk factors seem to be transport time, animal temperament and floor conditions.

Although most feedlots are aware of the condition, it is often misdiagnosed as an injury due to trauma or handling because lameness may start to appear within a few days after arrival.

This is why treatment is often delayed. In the meantime, the infection may spread deeper into the claw tissues and bone where it becomes untreatable and ends up with the animal being euthanized. It’s often a surprise to see what’s going on in the hoof when the animal is necropsied, Jelinski adds. For more detail see our related story in this issue.

Sloughing hooves

Ergot toxicity has been more common in recent years with wet growing conditions more conducive to ergot bodies forming in cereal heads, says Jelinski. The severity of associated lameness problems tends to cluster by feedlot depending on where they source grain. Grain screenings in pelleted supplements are another source of ergot toxins.

Ergot toxicity may first show up as lameness in the feet. Over time a line of demarcation (splitting of the skin) may become evident between the dead and healthy tissue. Some hooves may be affected worse than others and in severe cases the entire foot or claw sloughs off.

“The degree of damage caused by ergot toxins depends on the amount of toxin consumed and animals may recover from low-level poisoning when contaminated grain is removed,” he says.

Prairie Diagnostic Services at the Western College of Veterinary Medicine in Saskatoon now has equipment in place to test feed for ergot toxins.

• From the Manitoba Co-operator: Frozen ears and feet – but not from the cold

Laminitis

In a healthy hoof, a layer of laminae cushioned between the hoof wall and the third bone (the bone coming down to the tip of the hoof) holds the bone parallel to the hoof wall. When laminae weaken or tear from the hoof wall, the third bone begins to rotate downward putting pressure on the sole.

Laminitis in feedlot cattle is associated with a rapid increase in highly digestible carbohydrates (grain) in the diet, which changes the acidity in the rumen and in turn kills off some types of digestive organisms that release toxins into the bloodstream as they die. The toxins cause swelling in blood vessels of the hooves leading to impaired circulation.

A hardship groove associated with an abrupt change in diet will become noticeable across the hooves as they grow out. Sole overgrowth, skinny claws (flipper feet) and other claw abnormalities may become apparent in time.

Once laminitis sets in there is no practical treatment, however, animals with mild cases may get along just fine on soft ground in well-bedded pens. Marketing affected animals in a timely manner is advisable.

Others

Bruises, sprains, torn ligaments, ruptured tendons and, the very odd time, fractures can happen during routine handling and in pens when animals jostle at the feed bunk.

Nerve and brain damage also cause peculiar behaviour and strange gaits which can be mistaken as lameness.

Spastic paresis is an example of a hereditable condition where sensors in the muscle bundles keep the leg muscle tight causing the hock to hyperextend with each step. A severe joint infection can trigger an acquired form.

Abscesses from needle injection sites too close to the spine have been known to create a “wobbler” when the infection pushes up into the spinal cord just behind the head.

“Lameness is, of course, an economic concern for feedlots because of the cost of medications and labour to care for the animals, but it’s equally an animal welfare concern because many lameness conditions are very painful and may become chronic,” Jelinski says. “Unfortunately, we can’t do much to manage the pain. Unless we know the condition has a chance of improving with appropriate treatment, it’s best to deal with it by early marketing or euthanasia.”

The post Lameness in feedlot cattle appeared first on Canadian Cattlemen.

The study was undertaken after Zilmax’s maker, Merck Animal Health, temporarily suspended sales of the additive last year when concerns emerged in some quarters that it might cause lameness in cattle, said Ty Schmidt, a UNL animal scientist, who worked with colleagues including Jeff Carroll and Nicole Sanchez, both of USDA-ARS.

During the 26-day study, scientists collected blood, via catheters; body temperature; and video images from 20 heifers, which were divided into two groups, with half receiving Zilmax at the recommended dose and half not receiving it. On the last day of the trial, four days after Zilmax supplementation was discontinued, heifers were exposed to a simulated stress event to mimic the stress response that would be anticipated in cattle being shipped from the feedlot to packing plant. At the conclusion of the trial, heifers were harvested at UNL and their hearts, liver, lungs, kidneys and adrenal glands were studied.

• More from the Canadian Cattlemen: Merck wants to test Zilmax on 240,000 cattle but beef industry resists

Results from the study demonstrated some differences in physiological and endocrine markers of stress and muscle accretion in heifers that were supplemented with Zilmax compared to heifers not fed Zilmax. Heifers fed Zilmax had an increase in parameters that indicate increased muscle mass. The increase in these parameters was expected, as the drug label for Zilmax includes statements pertaining to increases in creatinine and creatine phosphokinase, Schmidt said.

Results from this study, he added, also demonstrated that heifers supplemented with Zilmax had a decreased production of the stress hormone cortisol, and decreased body temperature during the simulated stress event. Histopathology of the heart, lungs, liver, kidneys, and adrenal glands revealed some differences between the heifers supplemented with Zilmax and the heifers not receiving Zilmax. The livers and right adrenal gland of the Zilmax heifers were slightly smaller than heifers that were not fed Zilmax, but there was no difference in lungs, kidneys, or heart.

“Overall, the results of this trial indicate that while there are variations in the body temperature, endocrine and metabolic parameters and histopathology of major organs of Zilmax supplemented heifers, these differences are minor and show no indication that supplementation of Zilmax is detrimental to the health or well-being cattle,” Schmidt said.

View the release on the University of Nebraska-Lincoln website.

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