Interdigital Dermatitis - Cattle

Also know as: Scald — Slurry Heel — Stable Footrot — Heel Erosion — Heel Necrosis

Introduction

Interdigital dermatitis is caused by the anaerobic bacteria, Dichelobacter nodosus.

This condition has been confused in the literature with foot rot but the clinical signs of the two diseases are distinctly different. However, terminology is confusing with the equivalent UK/US expression being either heel necrosis, slurry heal or heel erosion (Blowey, 2008). It should not be confused with digital dermatitis.

Interdigital dermatitis (ID) is caused by Dichelobacter nodosus, however, different genotypes of this organism cause foot rot in sheep compared with those causing ID in cattle. Transmission of the disease between sheep and cattle has not been reported.

It is hypothesized that ID plays a role in the evolution of other diseases such as foot rot, digital dermatitis, and heel erosion.

D. nodosus and Fusobacterium necrophorum have been consistently isolated from lesions. However, other organisms frequently present in the interdigital space also play a part in the progress of some of these diseases.

Distribution

Interdigital dermatitis appears to be endemic in most countries where cattle are densely concentrated.

Signalment

Cattle of any age, breed or sex are predisposed to this condition.

There is a low incidence of ID in cattle at pasture. However, infection can build up wherever the traffic in cattle is high. As the climatic conditions deteriorate in the autumn, the prevalence of the disease increases. ID is therefore most prevalent when the feet of cattle are continuously bathed in slurry and is commonest during winter months.

Clinical Signs

ID is a mild superficial infection of the skin between the claws. In most instances, ID is a benign condition rarely causing lameness and is not associated with any systemic disease.

The first stage of the condition appears to be a wet dermatitis of the skin between the claws.

Secondly, fluid oozes to each end of the space between the claws and forms a crusty scab, which may also be occasionally observed on the dorsal surface of the digits. Affected animals are not usually lame or irritated at this stage.

As the condition progresses, the heels of the hind feet start to erode and become quite raw. This stage can be painful; the animal shows signs of lameness and the hind limbs will be held further back than is normal. The horn beneath the heel will increase in thickness.

Finally, chronic irritation of the skin between the claws of dairy cows is the commonest cause of corns (fibromas) developing on one side of the space.

Signs include generalised lameness or stiffness and limping on affected limbs. These limbs may also show signs of disuse atrophy in chronic conditions and swelling in acute conditions.

The animal may be pyrexic and have a reduced milk yield or weight gain and may show signs of weight loss. It may be noted that the animal is at the back of the group and is unable to walk at usual speeds.

There may be an under-running of the hoof on close examination and a grey exudate forming a scab in the interdigital space will usually be one of the first signs of the condition. Later the area may also be abscessed, brittle or cracked. There will be a foul odour from the foot.

Diagnosis

Clinical signs and history, with a detailed lameness examination and physical examination of the hoof are indicative of the disease due to the characteristic appearance and location of lesions.

Differential diagnoses include digital dermatitis and foot and mouth disease. These need to be eliminated and can be done so be detailed physical examination by an experienced clinician.

Laboratory diagnostic tools include the identification of Dichelobacter nodosus by immunofluorescence technology from smears of lesions.

Treatment

In severe cases, the lesions should be cleaned and dried, after which a topical bacteriostatic agent should be applied; such as a 50% mixture of sulfamethazine (sulfadimidine) powder or anhydrous copper sulphate.

Alternatively, an animal can be confined in a 5% copper sulfate footbath for an hour, twice-daily for a number of weeks.

The use of systemic therapy, including antibiotics, is not warranted.

Control

Control measures include good husbandry, such as reducing the presence of slurry when cattle are housed in winter and enforcing or introducing housing systems that keep claws dry and clean are the most important.

Regular foot trimming helps to avoid complications.

Footbathing, commencing in late autumn and before clinical cases can be identified, is essential in herds known to be infected with Dichelobacter nodosus. Solutions of 3% formalin or 5% copper sulfate are usually effective. Be aware that these chemicals biodegrade slowly. Weekly footbathing may be sufficient in the late autumn, but the frequency may have to be increased in late winter.

There is no vaccine currently available for cattle with this condition.

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References

Blowey, R. (2008) Cattle Lameness and Hoofcare. 2nd edition. Old Pond Publishing Ltd.

Hanna, P., Lofstedt, J., Duivenvoorden, P (1994) Papillomatous digital dermatitis in a Canadian dairy herd. Canadian Veterinary Journal, 35(10):657; 2.

Rutter, B (1984) Lameness in dairy cows: incidence in Argentina. Proceedings of the 8th International Symposium on Disorders of the Ruminant Digit, Banff, Canada, 40.

This article was originally sourced from The Animal Health & Production Compendium (AHPC) published online by CABI during the OVAL Project. The datasheet was accessed on 31 March 2011.