The following column appears in print and digital versions of the November 2015 issue of Dairy Herd Management.
Attention to dairy cattle care, lameness is becoming an increasingly important issue. However, research has shown we are not making progress in reducing cases of a major cause of lameness, digital dermatitis. Further research recently conducted at the University of Wisconsin-Madison has revealed new methods of dealing with digital dermatitis.
Digital dermatitis, commonly known as hairy heel warts, is caused by an infectious organism called a treponeme, present in confinement dairy environments. The trepomene invades the tissue on the cow’s heel and erodes the epidermal layers, causing severe pain and a variety of clinical signs.
If you’ve ever looked between the heels of a severely lame cow and seen a red, raw, circular lesion, you can diagnose digital dermatitis. Recently, a new classification system was developed to identify its severity (see photos).
The two most important stages of digital dermatitis are M2 and M4.
The M2 stage is characterized by red, raw lesions, and cows typically exhibit lameness. Identifying and properly treating cows with M2 lesions very early remains the most effective method of treatment.
Identifying cows with digital dermatitis must be done more often than the frequency of a routine trim. Assign a person on the dairy to search for cows with M2 lesions, and lame cows in general. This is best done at the time of lockup or in the parlor.
The good news, if a cow is identified early in the M2 stage, lesion treatment can be effective. Research has shown an oxytetracycline wrap is the most effective treatment for the M2 stage. Apply a small amount of oxytetracycline powder or solution to a 4x4 gauze pad and wrap with a very small amount of wrap material. The goal is for the wrap to fall off in 1-2 days. If it hasn’t fallen off, it should be removed. It is important to note using oxytetracycline in this manner is an extra-label drug use. Work with your veterinarian to determine the appropriate milk withhold time when using this treatment method.
The M4 stage is the chronic, proliferative stage, where you may see the characteristic frond-like projections. Cows also typically exhibit some degree of lameness during this stage.
Treatment is extremely ineffective after a cow reaches the chronic M4 stage. If you notice a cow with digital dermatitis that has a large, red, raw lesion, you may have already lost the battle.
PREVENTION IN HEIFERS
It is extremely important to prevent digital dermatitis in your heifers. Heifers developing digital dermatitis are about 40% more likely to develop lesions when they enter the lactating herd.
A footbath is an effective treatment method for digital dermatitis prevention in heifers, but heifer facilities are typically not designed for routine footbath applications.
Studies have also shown a particular feed-through mineral supplement has been effective in reducing digital dermatitis incidence in heifers.
Genetics also plays a part in controlling digital dermatitis, but it appears farmers are not currently specifically selecting for resistance traits.
FOOTBATH DESIGN, MANAGEMENT
Footbaths are the mainstay of prevention in lactating herds. A review of research suggests copper sulfate is the best product to use in footbaths, with formaldehyde a closesecond. Some prefer not to use formaldehyde because of humanhealth concerns.
However, neither product is effective unless the footbath is regularly used, and footbaths are not effective in treating cows with active M2 lesions.
Develop a footbath plan and strictly adhere to it. Make it part of a regular herd health routine. Newer footbath designs are typically longer (10 feet) and narrower (24 inches) than previously recommended footbaths. This size allows the cow to place her rear feet in the footbath solution at least two times while walking through it.
A properly designed footbath allows for more effective application of solution, which in turn can give producers the opportunity to use a less-concentrated solution and reduce the frequency of footbath use.
Remember, the mainstays of a digital dermatitis control program are reduction of digital dermatitis in heifers, promptly identifying and treating M2 lesions, and a consistent footbath program. With new strategies in digital dermatitis management, we can make strides to reduce the incidence of this disease.
Gabe Middleton, DVM, is a partner with Dr. Mel Wenger at Orrville Veterinary Clinic, Orrville, Ohio. Contact him at email@example.com.
Identification, Prevention and Control of Claw Lesions features in-depth information on causes of lameness, the anatomy of the foot, claw lesions and diseases, nutrition, and hoof and claw care. It was developed by the Zinpro International Bovine Lameness Committee.
For more information, visit www.zinpro.com.
FIVE STAGES OF DIGITAL DERMATITIS (DOPFER ET AL)
M0 – HEALTHY CLAW
M1 – EARLY/SUBCLINICAL
M2 – PAINFUL/ACUTE ULCER
M3 – HEALING
M4 – CHRONIC/HAIRY WARTS
M4-1 – CHRONICALLY RECURRING
(PHOTOS COURTESY ZINPRO CORP.)