This article was submitted by the American Association of Bovine Practitioners Lameness Committee.
Misuse of grinders can lead to removing too much of the hoof's outer wall.
Your goal is to balance the weight bearing between the inner and outer claws, correct the altered displacement of weight from heel to toe in overgrown claws, return the claws to normal shape and proportions, and to find and correct early lesions.
A good hoof-trimming program is essential in order to prevent lameness. But it is equally true that lameness problems can result from poor trimming.
It is not unreasonable to recommend that cows should be trimmed at least twice per lactation, usually around dry-off and around 70 to 150 days in milk. Some cows with poor hoof conformation require more frequent trimming (for example, every 60 to 90 days), and cows with long lactations should be trimmed again prior to dry-off. There also are benefits in some herds to trim heifers before their first calving provided that the job is done by a skilled trimmer. It also is common for most lame cows to be seen by the trimmer at one of the routine visits.
How much trimming are we talking about? Let's assume a typical 1,000-cow dairy, trimming twice per lactation, with a lameness incidence of 45 cow cases per 100 cows per year. The expected number of trims would be approximately (1,000 x 2) + (45 x 1,000/100) = 2,450 cow trims per year. If a trimmer serves 50 cows per visit, that would require 49 (2,450 divided by 50) visits per year, meaning that the herd should be visited weekly.
If the number of trims recorded is much less than the expected number, then it is clear that the hoof trimming program described is not being adhered to. If the number is far in excess of the expected number, then the rate of lameness may be very high, or some cows may be being trimmed too frequently due to chronic lameness. These cows need to be identified so that they are not continuously presented to the trimmer as a "new case" of lameness each visit.
If the number of cows trimmed per day exceeds around 50 to 60, then you should check on the quality of work and how cows are selected for trimming. Trimmers who work too quickly may miss lesions, not apply hoof blocks where needed, and make more trimming errors.
Use the seven-point check here to check on your hoof trimming program. If problems are identified, discuss the issue with the trimmer, and try to understand why cows are being treated incorrectly. Work with the trimmer to correct the issues and improve the hoof health of the cows in your herd.
Here are some common hoof-trimming errors
1. Excessive removal of the outer wall of the hoof. This is common where trimmers misuse grinders. It's okay to round off the toe end of the claw but not to remove the side wall further back towards the heel. This can result in more white line disease.
Test: After trimming, the claw side wall should be healthy and still show faint horizontal ridges. It should not be pale in color and smooth, and there should be no evidence of grinder tracks.
2. Trimming toes too short. For the average mature Holstein, the front hoof wall from a point about midway down the periople to the toe should measure at least 3 inches. (You can locate the periople with finger pressure. It is the soft horn between the skin and the hard wall horn.) If the toe is trimmed too short, then the sole will be made too thin in the toe, and the cow will be susceptible to white line fissure development in the inner and outer wall region of the toe.
Test: Measure the front claw wall using a 3- inch marker from the hard horn about midway down the periople to the toe.
3. Excessive trimming of the heel of the inner claw of the rear foot. Among cows on concrete, it is common for the soles of the inner and outer claw to become worn excessively. Trimming should transfer weight from the heel of the outer claw to the inner claw and maintain the height of the inner claw in situations of excessive wear.
Test: When the length of the outer groove (the line on the side wall where the perioplic horn wraps around to join the horn of the wall) is 1.5 inches or less, the sole/heel of the weight-bearing surface may give with finger pressure, indicating that it is too thin. This may be due to wear or trimming. After trimming, examine the inner claw heels. There should be no evidence of trimming to the rear of the outer groove.
4. Removal of the outer wall of the toe of the inner or outer claw. The removal of horn from around the interdigital space from the inner and outer claw (modeling) should be confined to the area to the rear of the inner groove where the white line leaves the weight bearing surface. The inner wall at the toe is a weight-bearing surface that should not be removed.
Test: Watch the trimmer shaping the interdigital space; examine recently trimmed claws to make sure that the inner wall is intact, or both.
5. Trimming the sole too thin. The healthy sole should be at least 1/4-inch thick and not give under firm thumb pressure or reasonable pressure with hoof testers. Thin soles will predispose the cow to white line fissures in the toe region and toe ulcers.
Test: Examine cows that have been trimmed recently and those that have not been trimmed for more than four months. Determine sole thickness before and after trimming to ascertain whether the problem is due to the environment, the trimmer, or a combination of the two. Consult treatment records for evidence of having more lesions located in the toe region of the claw.
6. Trimming the sole of claws with extreme concavity rather than flat. While pastured cows develop overgrown wall horn and concavity of the sole, cows kept on concrete should not be trimmed with extreme concavity of the sole. When a cow stands on concrete with concave soles, the claws will be pushed apart, increasing weight transfer to the inner components of the inner and outer claw. This may predispose the claw to sole ulceration and hemorrhage in the typical site, below the back edge of the pedal bone.
Test: Examine recently trimmed claws, and make sure that there is at least 3/4 inch of sole horn adjacent to the white line on the inner and outer claw that is trimmed perpendicular to the long axis of the limb to provide claw stability.
7. Shortening of the toe without proper reduction of sole thickness. Overgrowth in the toe should be removed by shortening the toe and thinning the sole in the toe region to leave 1/4 inch of thickness at the cut end of the toe. However, a common error involves trimming the front hoof wall down to shorten the toe, with minimal removal of sole horn. This does nothing to correct weight balance and leaves the overgrown sole horn in the toe region of the claw.
Test: The trimmer must be observed to detect this problem. They typically will use a grinder to thin the front hoof wall down and avoid trimming the sole, but this technique must be differentiated from the trimming of corkscrew claws where the front wall curvature is corrected before the sole is trimmed.
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