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Digital dermatitis (DD) is a claw disorder that was first reported in the seventies by Cheli & Mortellaro (1974). DD affects mainly dairy cattle all over the world and leads to substantial economic losses due to reduction in milk yield, and secondary diseases causing by disruption of skin and claw horn integrity (Blowey & Sharp, 1988). The disease, however, has also been reported from beef cattle herds. DD primarily affects the skin near the coronary band of the bulb region next to the interdigital space, but has been reported recently to be present on the surface of tylomas, on sole ulcers, wall ulcers and at other sites of the skin of the distal part of the limb.
Those lesions have been termed “non-healing lesions” due to sometimes frustrating outcomes after intensive treatment. Although DD is multifactorial by its origin, bacteria belonging to the genus Treponema are a constant finding in DD lesions (Döpfer et al.,1997; Blowey et al., 1992). Various risk factors have been reported including deficits in hygienic conditions on the farms, keeping cows in-house the whole year around, unsuitable hoof baths, larger farms, high animal density, genetics, young age (Somers et al., 2005). DD is characterized by a great variety in its clinical appearance. The acute disease, however, likely turns into chronicity with flare-ups of the acute stage in intervals. (Döpfer et al., 1997) described the different lesions that can be observed in cows affected by DD. The M-0 stadium is characterized by a completely healthy skin at the interdigital lesion. The observer is able to look through the interdigital cleft. The M-1 lesion is formed by a small ulceration (< 2 cm in diameter) of the interdigital skin which is most often invisible unless one uses a forceps to widen the interdigital cleft. The M-2 lesion is the acute form of DD, which on most farms is the only disease entity that is noticed by the farmer. The M-2 stage has a
diameter of > 2cm and is painful on physical touch. This acute stadium of DD is characterized by ulcerative circular lesions that have a strawberry-like appearance and which evaporate a distinct odor (Cornelisse et al., 1981). Antibodies are formed that are directed at certain surface antigens of Treponema species. However, such antibodies are not protective, but rather do reflect the bacterial burden within the
M-2 lesion. Following (topical) treatment with an antibiotic (tetracycline) or a non-antibiotic (salicylate, zinc-copper-chelate) containing spray or ointment the lesions proceed to the M-3 stage, which is characterized by a scab on the surface of the lesion. This lesion is painless and can proceed into the M-0 stage, but most often develops into the chronic M-4 stage, which is either characterized by hyperkeratosis (M4H) or by a papillomatous appearance (M4P). The chronic stages are not painful and – in most cases do not cause lameness. Treponema in a cyst stadium are found in the deeper layers of the skin in patients displaying the chronic forms of DD. Encystation is a way how Treponema evade the recognition by the host’s immune system. Although the disease can remain for months in the M-4 stage, the M-2 stadium can evolve from a small ulceration that is present within the hyperkeratotic skin of the M-4 stage, termed M-4.1 (Berry et. al., 2012). Once DD has turned into the M-4 stage complete resolution of the process (M-0) is less likely than chronicity. Due to the constant irritation of the skin next to the bulb region or where else the lesions are located an enhanced horn growth has been observed. The newlyformed horn, however, is of inferior quality and can on its own cause secondary disorders of the claw horn such as heel horn erosion and bulb ulceration. DD is a disease of the fibrocyte but not the keratocyte. Early treatment of youngstock for DD has been shown to contribute to a complete recovery. The golden standard of DD-treatment still is the topical application of an antibiotic spray like oxytetracycline (OTC), which is most effective in combatting the M- 2 stage. Most lesions, however have been demonstrated to turn into the chronic stadium after topical treatment with tetracyklines. In addition, hoof baths are used for combatting DD on the farms. In most cases farmers choose for formaline or coppersulfate containing formulations. Cook and Orsel report that hoof baths in most cases do not fulfil the criteria that are required. The position of the hoof bath is inappropriate, or its dimensions are too small. The concentration of the biozide (a formulation registered for disinfection of the digital skin and the hoof horn) is not appropriate or the hoof bath is not renewed subsequent to a passage by 200 animals.
Detection and prompt treatment of acute lesions is critical to limiting the spread of DD on the farm (Berry et al., 2012). The use of bandaging in treating DD has been discussed controversial. While some veterinarians and claw trimmers prefer bandaging a limb that is affected by DD others prefer to treat the lesions solely with topical application of sprays. Differences in bandaging techniques, tightness, duration, and waterproofing in clinical research may also obscure the actual effectiveness of bandaging in DD treatment.
Material and Methods
This randomized clinical trial took place between July 2013 and November 2014 on a commercial Holstein dairy farm in Northeastern Germany. All cows were freestall housed, had concrete flooring, and participated in routine claw trimming 2-3 times a year. This study included cows with one or more acute, ulcerative DD lesion (M2, n=196) on their hooves upon first examination. All lesions were
located above the coronary band. Cows were then randomly assigned to either the group of animals receiving a topical treatment with a chlortetracycline containing spray and a bandage while members of the second treatment group received the treatment but did not get a bandage. Parity ranged from heifers to cows in their 4th lactation.
Clinical observations and recording of lesions
All hooves were brushed, cleaned with soap and water, dried with a towel and trimmed by a
professional hoof trimmer. Lesion size and locomotion were evaluated, and followed in 7 dayintervals for 4 consecutive weeks (7+3 d), resulting in a total of 5 observations. DD lesions were macroscopically classified and recorded using the M-system as reported by Döpfer et al. (1997) and Berry et al. (2012). There were slightly more cows in the bandaged group (n=44, Group 2) than the non-bandaged group (n=41, Group 1). A standardized bandaging technique was applied by the same person to ensure methodological reliability.
Overall, the findings of the present study found that bandaging reduced the development of M4 lesions significantly. Within a survival time of four weeks, the healing of DD lesions for bandaged cows was more than double of that for non-bandaged cows regardless of treatment type. Bandages do not only prolong exposure to the therapeutic, but also protect lesions from environmental harm and slurry and by this means facilitate the healing process. Supporting the combined use of treatment and bandaging, Toholj et. al. (2012) found that the single use of a bandage showed no significant process in healing, whereas lesions bandaged after local topical CTC treatment had the highest cure rate of 86.1%. In conclusion, most of the lesions turned into the M-0 stage after at least two or three treatments with topical chlortetracycline and a bandage, while most of the lesions in animals treated solely by topical application of chlortetracycline spray turned into chronicity.