Concurrent follicular dysplasia and interface dermatitis in Boxer dogs.

Recurrent or persistent follicular dysplasia and interface dermatitis are described in nine Boxers. Data on age, sex, seasonality of alopecia and histopathological features of the follicular dysplasia in these nine Boxers are comparable with those described in previous reports. The interface dermatitis was characterized by multifocal annular crusted lesions confined to the areas of follicular dysplasia. The inflammatory lesions were neither pruritic nor painful and affected dogs were otherwise healthy. Histopathologically the clinically inflammatory lesions were characterized as an interface dermatitis. Immunohistochemical studies failed to demonstrate immunoglobulins or complement at the basement membrane zone or within blood vessel walls. In dogs with recurrent or persistent disease, the follicular dysplasia and interface dermatitis ran identical, concurrent courses of spontaneous remission and recurrence, or persistence, respectively. One dog with persistent disease was treated successfully with tetracycline and niacinamide for the interface dermatitis, and melatonin for the follicular dysplasia. Although the aetiopathogenesis of this newly described condition and the relationship between the two histological reaction patterns are not known, photoperiod and genetic predisposition appear to play a role.

The role of endothelial cell-derived inflammatory and vasoactive mediators in the pathogenesis of bluetongue.

Bluetongue is an insect-transmitted disease of sheep and wild ruminants that is caused by bluetongue virus (BTV). Cattle are asymptomatic reservoir hosts of BTV. Infection of lung microvascular endothelial cells (ECs) is central to the pathogenesis of BTV infection of both sheep and cattle, but it is uncertain as to why sheep are highly susceptible to BTV-induced microvascular injury, whereas cattle are not. Thus, to better characterize the pathogenesis of bluetongue, the transcription of genes encoding a variety of vasoactive and inflammatory mediators was quantitated in primary ovine lung microvascular ECs (OLmVECs) exposed to BTV and/or inflammatory mediators. BTV infection of OLmVECs increased the transcription of genes encoding interleukin- (IL) 1 and IL-8, but less so IL-6, cyclooxygenase-2, and inducible nitric oxide synthase. In contrast, we previously have shown that transcription of genes encoding all of these same mediators is markedly increased in BTV-infected bovine lung microvascular ECs and that BTV-infected bovine ECs produce substantially greater quantities of prostacyclin than do sheep ECs. Thus, sheep and cattle were experimentally infected with BTV to further investigate the role of EC-derived vasoactive mediators in the pathogenesis of bluetongue. The ratio of thromboxane to prostacyclin increased during BTV infection of both sheep and cattle, but was significantly greater in sheep (P = 0.001). Increases in the ratio of thromboxane to prostacyclin, indicative of enhanced coagulation, coincided with the occurrence of clinical manifestations of bluetongue in BTV-infected sheep. The data suggest that inherent species-specific differences in the production and activities of EC-derived mediators contribute to the sensitivity of sheep to BTV-induced microvascular injury.