With most animal welfare audits currently assessing bodily injuries to our dairy cows, there is growing interest into their causation and significance.
Hair loss, abrasion and swelling are commonly noted on the hocks, the knees (carpus), the neck and the back, and since they are more common in confinement-housed cattle, it is easy to conclude that they result from some abnormal interaction between the cow and her environment.
By far the most researched of these injuries are those that affect the surface of the cows’ hocks, with 14 or more peer-reviewed studies of their prevalence published since 2000.
Figure 1 shows the prevalence of hock injuries in these studies around the globe, with a range from 23.5 percent of cows affected all the way up to 81.2 percent, with no significant difference between tiestalls and freestalls.
With a mean prevalence of 53 percent across all studies, it is easy to conclude that this is a significant problem.
These studies documented any injury to the hock – including hair loss, abrasion, ulceration and swelling. There are fewer studies documenting the prevalence of knee (carpal) injuries, but those that have been published point to a similar prevalence of around 50 percent of cows affected.
Even less information is available on neck and back injuries, with prevalence estimates suggesting around 4 to 20 percent of cows are impacted.
In contrast to lameness, which is estimated by locomotion scoring and where there is general agreement across systems as to what constitutes a lame cow, there lacks similar agreement across studies documenting injury. In some, any amount of hair loss is documented, while in other studies, the hair loss must exceed a certain area, such as the size of a quarter.
Definitions become even more confused when severity is included with no general agreement regarding the degree of swelling or the amount of abrasion or ulceration that constitutes a “severe” lesion. This is likely important as abrasion or ulceration and swelling present an obvious source of pain and infection risk for the cow, while the effect of hair loss on the welfare of the cow would likely be much less.
However, recent work on mild hair loss lesions of the hock skin has identified evidence of inflammation, suggesting that even these lesions cannot be ignored as a potential source of pain and discomfort to the cow.
Currently, we believe that hair loss over the hocks and knees likely represents a friction injury as cows rise and lie down on mat or mattress beds since the presence of lesions is highly correlated with this type of stall surface compared to the use of well-managed, deep, loose-bedded stalls such as deep sand.
Stall obstructions to normal rising and lying movements, such as poor neck rail placement, will likely exacerbate the problem as this will lead to the cow shuffling her body across the stall surface as she tries to get comfortable. There are, however, risks associated with deep bedding when it is poorly managed. An exposed rear curb may cause an increase in dorsal hock lesions on the top of the calcaneus bone.
Injuries to the inside surface of the hock have been reportedly caused by shallow, poorly filled beds and cows lying with their rear limbs hanging over the exposed rear curb, creating a pressure sore that can be life-threatening when severe. Elevated rates of hair loss over the knees has also been reportedly associated with the use of coarse recycled sand.
Severe hock injuries are likely caused by a change in cow behavior. While several studies have shown associations between hock injury and lameness, I believe that hoof-related lameness is the cause of the severe hock injury rather than the other way around – at least initially.
We know lame cows have longer lying bouts than non-lame cows and struggle to transition from lying to standing and standing to lying. This reluctance to change position and relieve pressure contributes to the development of a “bed sore” or decubitus ulcer – hence, the strong association between lameness and hock injury. This is supported by a recent United Kingdom study that confirmed lameness is not the result of severe hock injury, but the precursor of it.
Hair loss, swelling and skin abrasion have been noted in other regions of the body such as the neck, the back and the area around the hook bones. Neck injuries have been associated with poorly located feed rails at the feedbunk caused by cows applying pressure to access feed or incorrectly located tie rails in tiestalls.
Back and hook injuries are believed to result from stall design and use issues. Other injuries generally occur at low frequencies, but may present as a problem on an individual farm, often related to either an animal handling issue or a building design problem that would need to be addressed specifically for the farm in question.
Producers that must create an action plan to reduce the risk for these injuries on their farms must look to the likely cause. Hair loss over the hocks and knees will likely respond rapidly over a few weeks to the provision of a deep, soft-bedded surface and attention to any stall design risks that prevent normal rising and lying movements.
More severe lesions with ulceration and swelling are likely associated with a failure to prevent hoof-related lameness, coupled with a firm stall bed, and attention to hoof health should be a priority. Healing of these lesions will be slower, over weeks to months. Neck lesions commonly respond quickly to elevating the feed rail (or tie rail in a tiestall) and moving it forward of the feed curb.
This relieves the pressure exerted by cows pushing against it while feeding. Other injuries are usually situation- specific and may take a little time to figure out, relying on observation of cows in the stalls, in the parlor, feed area and handling areas to determine the solution. 
PHOTO: Providing a deep, soft-bedded surface and attention to any stall design risks that prevent normal rising and lying movements can help recover hock and knee hair loss and mild abrasions within a few weeks. Photo by Peggy Coffeen.
Nigel Cook is currently chair of the Department of Medical Sciences at the University of Wisconsin – Madison School of Veterinary Medicine and manages the Dairyland Initiative.
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Nigel B. Cook
- Veterinarian
- UW – Madison School of Veterinary Medicine
