Bovine hyperkeratosis is a polyetiologic disease that is increasingly widespread at high milk yielding dairy farms. Clinical manifestation is characterized by focal skin lesions with distinct borders. A clinical study and observation were carried out on 26 Holstein-Friesian dairy cows. During the initial phase of the condition, the skin of the affected cows was itchy, hence the animals tended to lick the skin lesions, or else rub against surrounding objects, with the resultant formation of single spots of raised coat and skin flaking resembling dandruff. These changes appeared on the posterolateral upper sides of the pelvic limbs and around the vulva. Distinct thickening of the wrinkled skin was observed as a result of excessive growth of the epidermis. The superficial part of the skin on major portions of the lesions was dry, corrugated and covered with numerous scales. The epidermis was dry, thickened and rough, with cracks showing the reddened dermal layer. When touched, the animals reacted as if in pain. The disease generally progressed into a chronic condition. In the studied cases, histopathological examination confirmed hyperkeratosis with widened hair follicle infundibulums filled with keratin, the swelling of sweat glands, epithelial atrophy of sweat glands, infiltration of inflammatory cells between and around blood vessels,  and  massive expansion of keratinized layers of the epidermis. The content of both calcium and magnesium as well as copper, zinc, iron and manganese in grain, roughage, mineral mixtures and in other feeds met the requirements of dairy cows. Blood biochemistry profiles revealed only slightly lower serum calcium values, while zinc values were within the reference range. However, the zinc concentration in skeletal muscles and in the skin was reduced. The mean serum alkaline phosphatase (ALP) activity in the tested animals was also somewhat decreased. Adverse environmental factors such as direct skin contact with faeces and urine as well as zinc deficiency in the cows’ tissues were significant factors in the formation of skin lesions characteristic for hyperkeratosis.

19.4.2014