No one wants to have cows limping through their barn, afflicted with lameness. Yet, it is one of the most common and most costly diseases dairy farmers deal with. During an Iowa State University Extension “Dairy News and Views” podcast, two extension veterinarians discussed why lameness occurs even more frequently in two specific time periods: around calving and in the late summer and early fall.

Phillip Jardon pointed out that transition cows are one of the most susceptible groups of animals to contract a condition that causes lameness, such as sole ulcers or hairy heel warts. Though it might not set in right at calving, we can see cows develop hoof or mobility issues in the weeks and months after calving that trace back to how they were cared for during the dry period and early lactation, he said.

Calving brings on many hormonal changes in the cow’s body, but Jardon pointed to the hormone relaxin, which helps the pelvis relax so the cow can give birth, as a challenge to hoof health. “It doesn’t have a specific action on the pelvis; it also works on the ligaments and structures of the foot,” he explained.

Jan Shearer described that relaxin’s action causes enzyme activity that weakens the system of soft tissue that supports the suspension of the bone in the hoof’s claw horn shell. “When that happens, the bone will sink within the claw horn shell. What it ultimately does is compress all the tissues beneath that are responsible for the production of a horn in the sole, and that becomes the initiating reason in claw horn lameness,” Shearer explained.

Since relaxin is necessary for the cow to calve, farmers must limit this damage by focusing their efforts on reducing the pressure transition cows must put on their feet, the two agreed. Ensure that close-up cows and fresh cows have plenty of desirable stalls and bedding that encourage them to lay down.

Cool and comfortable

Although we are still early in the summer, barn fans around the country have likely already put in plenty of work this year. The potential for heat stress will only rise as we move through the next couple of months.

Heat stress is another reason cows are reluctant to lay down as much, and this again puts undue pressure on the feet. That is especially true if cows are perching in stalls in an attempt to cool down. More lameness is seen in the late summer and early fall no matter what part of the country you are in, Shearer said, and it is because of heat stress that keeps cows from resting. Jardon urged producers to do anything they can to keep cows cool so they will be more likely to lay down and remove the pressure being put on their feet.

Body condition plays into lameness prevalence because the fat pad of each foot serves as a shock absorber when cows are standing and walking. If cows are losing excessive body condition, fat is being pulled from the feet in addition to other parts of the body, making the cow more susceptible to lameness, particularly if they are already on their feet more often. But on the other hand, cows carrying extra weight are also putting excess pressure on their hooves and joints, so maintaining a moderate level of body condition strikes a healthy balance.

Finally, Jardon and Shearer noted that lameness most often occurs on the outer claws of the rear feet, and this is largely an indicator that it is being caused by cow comfort concerns. A nutritional cause would inflict lameness on other claws as well, they pointed out. But because of the structure and location of the outer claw, ulcers, warts, and disease there is often a sign that management decisions can be made to help cut down on lameness.