Chronic wounds, such as venous ulcers and pressure ulcers, frequently remain unresponsive to currently available treatments. Several animal models of wound healing have been published, including models of impaired healing developed to mimic the clinical condition of chronic wounds better. We used a delayed wound healing model in the pig that uses irradiation of the skin prior to creation of the surgical wounds and characterized it histologically. Radiation was used on one side of the back prior to making four full-thickness wounds on each side. Clinical observations were performed to record granulation tissue, reepithelialization, and wound area as a function of time. Histology data were obtained at 1, 2, 3, and 4 weeks, and slides were stained with hematoxylin and eosin for general observations. Immunohistochemistry was performed using laminin as a marker for blood vessels, and the number, size, and circularity of blood vessels found in the granulation tissue were measured. Our results show that this model causes a delay in wound healing that is mostly apparent between days 7 and 15. Granulation tissue took more time to form and fill the wounds on the irradiated side, and blood vessels were slower to develop. Blood vessels were larger and more irregular in shape on the irradiated side than on the control side. After 2 weeks, healing resumed, indicating that the induced damage was not irreversible. These results suggest that this model can be used to test the effects of therapeutic approaches intended to treat chronic wounds.

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PubMedDate not supplied

The development of dermatitis (scabby-hip) on the hip and thigh of broiler chickens.

Broiler chicks grown on litter or in cages at high bird density developed skin lesions on the thigh and hip. Changes in bird denisty markedly influenced lesion incidence (100% at 0.0185 sq m of floor space per bird). The dermatitis was characterized by crusted dry "scabs" at the base of feather follicles and between follicles. The lesions often coalesced to cover wide areas. The scab consisted of a mass of pyknotic nuclei and cellular debris, and when the epidermis was intact there was little inflammatory reaction in the dermis or subcutaneous tissue. The epidermis was destroyed in some lesions, with heterophils penetrating into the subcutaneous tissue. Colonies of gram-positive cocci were present in the lesions.

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