Six dairy industry experts answer questions about the causes and ramifications of dairy lameness.
What causes laminitis?
Dr. Guard: The traditional view of the cause of laminitis was that it is purely a consequence of a toxic event with a cow, like severe mastitis or metritis or ruminal acidosis. While those causes are still important, it is now clearer that the causal pathways are multiple. Environmental influences, given some predisposing condition such as ruminal acidosis, have a major influence on what the claw lesion or claw disease turns out to be. These environmental factors, such as standing time, standing on unforgiving surfaces and bad floors, all make laminitis worse.
Dr. Shearer: In the Southeast, our hot, humid environment puts animals in heat stress, which seems to accentuate foot problems. We believe heat stress contributes to ruminal acidosis because of the way it influences cattle feeding behavior and other metabolic aspects in the cow. All these factors associated with heat stress seem to play a part in the laminitis syndrome.
What are the economic ramifications of laminitis?
Dr. Jones: Economic losses due to lameness are closely tied to the severity and longevity of the problem. If it results in culling or loss of the affected animal, those costs far exceed production costs in some cases. In others, if the nonproductive animal is left in the herd, the economic losses could be greater than eliminating the affected animal. The real cost of lameness is when you have to accelerate culling. The longer you extend the productive life of the cow, you will drive down the cost of owning that cow. From an economic standpoint, it is easy to see why lameness is such a critical issue.
Dr. Guard: We all agree that any disease that causes a cow to decrease in performance is something we all strive to prevent. However, research models fail to reflect the real world in that the decision to replace a cow should always be based on whether the next cow you put in her place can generate more profit. It has less to do with the number of lactations than the net present value of the cow you can put in her place.
Dr. Jones: I agree, but if lameness is causing the cow to be subpar, below the norm you expect for the herd, she is going to have to be culled. And when more productive cows enter the herd, the lame cow likely is going to be culled. If that happens after two or three lactations, it is at the expense of potential profit.
Dr. Cain: There is one issue that I would bring to mind – conserving of equity. If you cull so hard to improve production, you can end up losing equity in your whole operation. That is a real-world scenario too, and I have seen operations not be able to sustain themselves because their equity base keeps getting smaller as they strive to increase production.
What is the role of a hoof trimmer in preventing laminitis?
Dr. Berry: I see the veterinary practitioner as being the person to help train people on the dairy to identify cows that should be brought to the hoof trimmer. Once a dairy gets into a program, trimming all dry cows and those in the 2 to 3 locomotion score range, they will eliminate a lot of laminitis problems and save the producer a lot of money. It is a lot cheaper than treating the problem, because once you treat the problem, you still have that loss of production throughout lactation.
Burgi: There is no doubt that correct maintenance hoof trimming is the best way to reduce the severity of laminitis, but it is often a tough economic sale to make. Too many times, hoof trimming is looked at as an expense rather than an investment.
Dr. Berry: Trimming will not prevent laminitis, but when it happens, prompt trimming will help to balance the wear and growth on the claws and spread the weight over the corium, ultimately reducing the likelihood that this animal will develop a sole ulcer.
Dr. Guard: There are two general objectives of hoof trimming: to restore a normal weight-bearing surface to the claw (distributing the weight of the animal evenly) and to remove excess growth. If the rate of wear exceeds the rate of growth, then the trimmer has an immense challenge.
Burgi: Nature didn’t equip cows ideally to stand and walk on concrete. Through hoof trimming, we improve the balance and function of the hoof. Cows with properly trimmed hooves have an advantage, especially when they are forced to spend all of their time on concrete. If we don’t have a regular maintenance hoof-trimming program, it is very difficult to prevent laminitis.
What causes heel warts?
Dr. Berry: To quote my esteemed colleague, Dr. Richard Walker, “The exact etiology of hoof warts is unknown.” With that in mind, the cause of foot warts is multifactorial. There is a microbacterial component. Constant moisture and depleted oxygen are environmental conditions necessary to cause hoof warts to affect animals. Cows in dairies with constantly wet stalls are at a much higher risk for hoof warts. Where the causal bacteria reside and how long they survive outside the cow is not clear.
What causes footrot?
Dr. Berry: It is basically bacterial, but then there is a skin trauma component which doesn’t seem to be the case with digital dermatitis. Treatment for footrot is more efficacious, and footrot tends to be more of a sporadic problem. One year it can be really bad and the next year not bad at all.
Burgi: I agree it is sporadic. If we have a problem with digital dermatitis, sometimes there is more problem with footrot. The skin is opened up for the bacteria to enter. Producers who have a really good skin care program (healthy skin all around the claws) experience little problems with footrot.
Dr. Berry: I think moisture also contributes to footrot and interdigital dermatitis. But with footrot, it can infect a dry foot that has trauma from rocks or other objects that traumatize the skin.
Are there management and genetics issues to consider when dealing with lameness?
Dr. Berry: I think there is a genetic component to lameness and hoof structure and integrity.
Dr. Jones: Part of it is that we push for production and all of a sudden, we realize we have fed too high a ration and the cow is coming up with acidosis and lameness problems. Sometimes scaling back is better than dealing with the health problems associated with high-producing cows.
Dr. Berry: To me, most injuries I see are from cow comfort issues: where the pavement is too slippery and the cow goes spread-eagle, or cows getting injured going in and out of freestalls.
Burgi: I think there is a high correlation between flooring and footing and all the aspects of mechanical lameness or laminitis. PD
—Excerpts from “Dairy Lameness Roundtable” from Novartis Animal Health
Steven Berry, veterinarian and extension dairy management and health specialist at the University of California
Karl Burgi, hoof trimmer and dairy consultant, Dairyland Hoof Care Institute
Don Cain, Veterinarian, Central Nebraska Vet Service
Chuck Guard, D.V.M., Ph.D., faculty at Cornell University, working in the Ambulatory and Production Medicine Clinic
Bruce Jones, Ph.D., an agricultural economist with the University of Wisconsin-Madison
Jan Shearer, D.V.M., an extension veterinarian and researcher at the University of Florida in Gainesville