To read this article in French, click here.
Digital dermatitis (DD) affects more than 95% of cattle in husbandry systems under compromised hygienic conditions and with high cattle density. The resulting outbreaks of lameness and painful ulcerative lesions along the coronary bands of feet in dairy cattle are serious animal welfare and production concerns.
Preventive measures such as early detection of active DD lesions before cows go lame should be followed by prompt topical treatment according to well-designed treatment protocols. Combined with disinfecting footbaths that are applied in well-designed footbath troughs at the correct frequency, concentrations and pH, such interventions are essential to attain a degree of control over this infectious claw disease.
Focused on the control of active lesions alone, it is forgotten that many DD lesions turn chronic. Chronic, proliferative stages are typically called hairy heel warts.
These proliferative stages of DD represent reservoirs of infection because the wart-like protrusions of skin harbor large amounts of treponemes that are causally associated with DD among many other microbes at the skin-horn border of mostly hind feet. Severe hairy heel warts are for life. Therefore, it is necessary to be aware of the chronic consequences of DD.
Chronic consequences of DD are:
- Overly high heels of the claws
- Heel horn erosion in layers due to repeated disturbance of the horn formation
- Ulcerated pedestals of proliferative skin that harbor
- A deep, soiled pouch of affected skin tissue at the exit of the interdigital space
- Abraded claw tips resulting in blocky claws and irreversible claw conformation changes
- Ulcerative, incurable DD lesions in locations such as knee folds, hocks, teats and the midline in front of the udder
- Sole ulcers, wall abscesses, corns that are incurable – the so-called hairy attacks – or in need of surgical treatment under local anesthesia
There is a genetic predisposition for chronic DD, as has been reported since 2015. Recently, two genes have been shown to be associated with DD, which should trigger alertness to and intensify preventive resources for family lines of cows affected by chronic DD. Genetic testing for this predisposition to chronic DD is underway.
Training to recognize DD trends under customized prevention, control measures
Herdspeople should be trained to distinguish between first-time and repeat cases of DD that display proliferations and result in a continuous reservoir of infection for other cows. Footbath strategies implemented at too high frequencies, too high concentration of footbath agents and at extremely acidic pH (pH less than 3.0) contribute to the formation of chronic DD with all the consequences mentioned above. Herd management is part of this developing problem that starts in pre-calving heifers around breeding age and results in heifers joining the endemically affected lactating herd with chronic DD lesions after calving. What can be done to better prevent and control DD?
The first sign of a well-designed footbath strategy in endemically affected herds is the decrease of chronic proliferative DD lesions. The first signs of success are represented by the proliferative warts peeling off in flaps of tissue. An increase of chronic proliferative DD lesions under too aggressive footbath and topical treatment approaches is a sign for irritation of the already inflamed and ulcerated skin surfaces, resulting in more inflammation and proliferation of the superficial skin. The outcome of this repeated irritation by footbathing and topical treatments of DD lesions are repeated uncontrollable outbreaks of DD.
Attention for the trends in numbers of chronic DD lesions will make herdspeople gauge the effects of footbaths and topical treatments. Sometimes, less is more. Lower frequency and concentration of footbaths at less acidic pH, combined with less aggressive topical treatment agents that result in decreased numbers of chronic proliferative lesions seem counterintuitive to combat DD, but this is not the case. As soon as proliferative lesions peel off the hairy heel warts, the severity of reservoirs of infection is reduced, and severe future outbreaks are increasingly prevented.
Remember the partners in controlling, preventing DD
Hoof trimmers play an important role in alerting to proliferative and repeat cases of DD in addition to managing the changes in claw conformation and horn formation in DD-affected cattle. A well-trained hoof trimmer will treat DD lesions topically without resulting in chronic DD, correct the heel height without overtrimming, control heel horn erosion during functional hoof trimming and help heal sole ulcers, corns and wall abscesses associated with long-term DD lesions. The dairy’s hoof trimmer, herdsperson, nutritionist and veterinarian are all a part of preventing and controlling DD. There is no need and no place for aggressive chemicals in high concentrations that burn off DD lesions, because they result in chronic DD. Hoof trimmers and herdspeople able and willing to record lesions, observe and analyze trends in stages of DD, such as the M-stages, are the dairy’s partners. Such partners are able to customize DD prevention and control strategies using disinfecting footbath chemicals and topical treatment protocols to their best effects.
The herds that are testimonials to effective prevention and control of DD start with preventing DD in the pre-calving heifers. Continuous monitoring and recording of lesions under customized footbaths and early prompt topical treatment protocols in lactating cows results in a situation where DD is still present on the farm but without the periodic major outbreaks of lameness associated with DD; we call this the manageable state of disease for DD. Increases in milk production and longevity of cows will be the results of a zero tolerance for lameness associated with DD.
References are available upon request from the author. Click here to email an editor.
