DIGITAL DERMATITIS, BOVINE - NORTH AMERICA
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Date: 7 Aug 2014
Source: Producer.com [edited]
Digital dermatitis is found primarily in dairy cattle, but it does occur in beef animals, especially in feedlots. Digital dermatitis is a painful foot condition that causes severe lameness in cattle.
This highly contagious disease was 1st described in Italy in 1974 and has since spread around the world, primarily within dairy cattle.
However, the disease is also becoming an emerging threat in beef cattle.
It is most common in cattle kept in confinement, and although it can affect breeding cows, it has been identified primarily in feedlot cattle within the beef industry.
A research study in 2000 in the southeastern United States identified digital dermatitis in 29 percent of culled dairy cattle at the packing plant. The same study said 4 percent of culled adult beef cattle had lesions of digital dermatitis.
Outbreaks have been anecdotally reported in feedlots in Western Canada.
Digital dermatitis goes by many names including strawberry foot rot, raspberry heel, foot wart and hairy heel wart. These lesions may appear initially as a raw, red, oval ulcer on the back of the heel just above or at the coronary band.
The hind legs are affected in 85 percent of cases. Many of them often develop raised, hair-like projections or wart-like lesions, and some may extend up between the claws or appear on the front of the foot.
These raw skin lesions are incredibly painful, and cows will dramatically alter their gait and posture to avoid putting pressure on them. Animals will walk on their toes because the lesion is usually at the heel, which may cause the hoof on the heels to overgrow.
This condition may resemble a wart, but it isn't because warts are caused by a virus. This disease is caused by a bacterium in the "spirochete" family called treponema. Researchers still disagree about whether other pathogens are involved, but treponema has been the primary organism associated with digital dermatitis.
There are likely predisposing factors such as immunity, infectious and environmental components. Wet conditions and constant moisture with manure contamination are probably responsible for softening the skin and allowing the organism to penetrate the skin surface.
The disease is highly contagious and can spread rapidly and affect a large percentage of animals once introduced via the addition of new cattle into a herd.
Younger cattle tend to be more susceptible, and cases in dairy cattle tend to occur around calving. This suggests that immune system suppression may play a role in the disease.
Treatment has proven to be difficult and usually requires cleaning and drying the lesion and then applying an antibiotic on the skin in a bandage or with a topical spray.
Antibiotic sprays, which are usually a tetracycline mixture, need to be applied 2x daily, which is feasible in a dairy herd but highly difficult in a feedlot setting.
Injectable antibiotics are often used in conjunction with topical treatments, but there is limited evidence that they are helpful.
Prevention is focused on hygiene and pen conditions by trying to reduce stocking density, maintaining watering and feeding areas to avoid mud and manure accumulation and managing corrals to avoid wet areas.
Foot bath solutions such as copper sulfate, zinc sulfate and formalin control the disease in dairy herds but can be difficult to manage in beef cattle.
Cattle that live in settings where manure management is difficult to achieve should walk through foot baths 2x a day for at least 5 days a week, but this is difficult to achieve in a feedlot.
Once-a-week foot baths may be sufficient in more hygienic conditions, which is more practical in beef cattle herds.
Producers should consult a veterinarian before starting a treatment program. Foot baths require considerable effort to manage and need to be long enough and deep enough to allow for 2 dunks for each foot.
Researchers are attempting to create a vaccine, but results have not been promising.
Producers can attempt to prevent bringing digital dermatitis into their herds by avoiding contact with infected dairy cattle.
Hoof trimmers should disinfect their equipment between farms to avoid spreading this highly contagious disease.
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[This disease has been known for a long time and is primarily in dairy cattle, and although its encroachment into beef cattle is not necessarily new, it may be becoming more prevalent.
Digital dermatitis is a highly contagious, erosive, and proliferative infection of the epidermis proximal to the skin-horn junction in the flexor region of the interdigital space. Morbidity within a herd can be greater then 90 percent. It can affect any breed or age group, although young animals with a poor immune response are most susceptible. It spreads rapidly from newly acquired animals, or it may be introduced by any mechanical vector; e.g., boots or hoof trimming instruments.
The condition was 1st seen in European countries, but during the last decade, it has spread across the dairy-producing areas of the USA. The incidence in beef cattle appears to be minimal. The incidence is highest in loose-housed herds that are not kept clean. The prevalence is highest in the fall and winter and is lowest if the animals are pastured.
Two main types of lesions are seen. One is erosive/reactive; the other is proliferative or wart-like. Both forms cause varying degrees of discomfort and may give rise to severe lameness. Sometimes, one particular form predominates in one area, but both forms can be seen in the same animal. The 2 forms likely represent different stages of the disease process. Some of the variation may be due to concurrent interdigital dermatitis.
Herd outbreaks are best treated with a footbath containing oxytetracycline or lincomycin-spectinomycin. For optimal effect, the heels of the cows should be washed thoroughly before entering the footbath. Repeat treatments may be needed after 4-6 weeks, depending on the extent of the environmental challenge. Results of footbaths containing copper sulfate, zinc sulfate, or formalin have been poor to inconclusive. However, these footbaths may have a beneficial effect in reducing the prevalence of interdigital dermatitis, thus decreasing the susceptibility for digital dermatitis.
In advanced cases, individual treatment is necessary. The foot, especially the interdigital area, should be thoroughly cleansed to remove the prolific population of spirochetes. A single dressing of 36 percent muriatic acid can be applied carefully to the infected tissue and protected by a waterproof bandage. Repeated dressing with the caustic preparation is not advisable.
Topical dressing of the lesion and surrounding surfaces with soluble oxytetracycline or lincomycin-spectinomycin (66 g and 132 g/L of water, respectively) produces the best results. More than one treatment will probably be necessary. Topical dressings should be protected by waterproof bandages or a reinforced nylon device that can be affixed with Velcro closures. Oxytetracyline treatment has not resulted in detectable residual levels of the antibiotic in blood or milk. Extremely high parenteral antibiotic doses have been reported to help resolve severe lesions.
Topical sprays can be applied when the cows are recumbent. The nozzle of the wand of a portable unit can be applied directly to the lesion.
This is a useful follow-up technique to either foot bathing or direct application of medication. With extreme care, formalin may also be used to reinforce antibiotic therapy.
Digital dermatitis is exacerbated by filthy, wet conditions. Slurry removal and improved standards of hygiene are essential for control.
In herds in which this condition is not a problem, animals should be isolated for one month before being added to the herd. Effective vaccines are not available.
Portions of this comment were extracted from:
- Mod.TG
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[See Also:
2012
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Digital dermatitis - New Zealand: bovine 20120825.1262055] ...... sb/tg/msp/lm
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