Atypical digital dermatitis of bovine claw in dairy cows: clinical and histopathologic findings


1 Mehregan Veterinary Group, Tehran-Iran

2 Department of Pathobiology, School of Veterinary Medicine, Lorestan University, Khorramabad-Iran

3 Department of Pathology, Faculty of Veterinary Medicine, the University of Tabriz, Tabriz-Iran


BACKGROUND: Digital dermatitis is an inflammation of the skin on the bulbs of the heel
which cause lameness and economic losses. Atypical digital dermatitis is a new form of an
old disease which has been reported recently in the USA, UK and Netherlands. OBJECTIVES:
The purpose of this study is the clinical and histopathological evaluation of claw lesions with
exposed corium in cases of concurrent digital dermatitis in two endemically infected herds
without preventative herd strategies for BDD. METHODS: The majority of non-healing claw
lesion samples included in this study were taken from 'typical' clinical cases, namely, from
lame cows examined in the course of veterinary practice by one author over a period of 8
months in two commercial dairy farms in Iran. Fourty five lame cows with claw lesions were
selected for clinical and histopathological purposes. RESULTS: Examination of the affected
claws revealed a topical granular appearance, painful to touch, prone to bleed with distinctive
odour and extensive regional loss of the claw horn. Histologically, the epidermis was lost
completely over the extension of sole ulcer lesion. The underlying dermis was intensely
infiltrated by inflammatory cells, mainly polymorphic leukocytes, and in deep, newly formed
capillaries were embedded in the stroma. Hyalinized thrombi were also significant in small
blood vessels. In wall ulcer, there was extremely proliferative epidermis, 2-3 times with
severe acanthosis and rete ridge formation. Stratum corneum was hyperplastic. The stratum
corneum were filled with neutrophils, cellular debris and erythrocytes lodged in the
orthokeratotic stratum corneum. CONCLUSIONS: In all the observed cases, the disorder
included penetration through the horn capsule lesions to involve the corium, resulting in
damage of the horn-forming cells. This new manifestation seems to be a combination of
metabolic and infectious diseases.