Equine bullous pemphigoid IgG autoantibodies target linear epitopes in the NC16A ectodomain of collagen XVII (BP180, BPAG2).

Bullous pemphigoid (BP) is an autoimmune subepithelial blistering dermatosis of humans, dogs, cats and pigs. It is characterized by skin-fixed and circulating IgG autoantibodies that target one or both BP antigens. An immunological homologue of BP in humans was diagnosed in two horses with cutaneous and mucosal ulcerations as well as microscopic subepithelial vesiculation. Immunological investigations revealed similar findings for both the horses. Direct immunofluorescence demonstrated the presence of IgG deposited linearly at the dermoepidermal junction in mucosal and skin biopsy specimens. Indirect immunofluorescence testing confirmed the existence of circulating basement membrane-specific IgG autoantibodies. Using intact and salt-split epithelial substrates, serum IgG were shown to target antigens situated not only at the basal, but also at the lateral and apical aspects of stratum basale keratinocytes. Immunoblotting and ELISA corroborated that the IgG from affected horses, but not those from normal controls, exhibited high immunoreactivity against the NC16A extracellular domain of type XVII collagen (BPAG2, BP180). Equine BP could be proposed, therefore, as another spontaneous model of this most common basement membrane autoimmune dermatosis of humans.

The use of fluoroquinolones in veterinary dermatology.

The fluoroquinolones are a group of antibiotics with considerable application for use in veterinary dermatology. They are rapidly bactericidal against a wide variety of clinically important organisms including Staphylococcus intermedius and gram-negative enteric bacilli by virtue of interference with the supercoiling of bacterial chromosomal material. Their favourable pharmacokinetic features make them applicable in many animal species, and in a range of dose formulations. The only major clinical contraindication is that fluoroquinolones should not be given to young, rapidly growing dogs as they can induce a noninflammatory, erosive arthropathy. For many years the only veterinary-labelled fluoroquinolone available was enrofloxacin. The selection of a fluoroquinolone has become more complex now that there are more choices available. Orbifloxacin, difloxacin and marbofloxacin now join enrofloxacin on the veterinary market, although not all of these are licensed in every country. The use of fluoroquinolones in dermatology remains controversial. The authors recommend that fluoroquinolones be considered in circumstances where canine pyoderma has been refractory to appropriate 'first line' antibiotics. They are most useful in the management of recurrent pyoderma and in chronic, deep pyoderma with extensive scar tissue. In addition, fluouroquinolones frequently are the drugs of choice for canine ear infections caused by Pseudomonas aeruginosa.

Determination of skin concentrations of enrofloxacin in dogs with pyoderma.

OBJECTIVE: To compare serum and skin concentrations of enrofloxacin in dogs with pyoderma with those of clinically normal dogs and to evaluate concentrations in dogs with superficial versus deep pyoderma. ANIMALS: 16 clinically normal dogs and 16 dogs with pyoderma. PROCEDURE: Enrofloxacin (approx 5 mg/kg of body weight, PO) was administered daily to all dogs. Serum samples and skin biopsy specimens were obtained on day 1 at 3 hours after drug administration and on day 3 immediately before and 3 hours after drug administration. Samples and specimens were assayed by high-performance liquid chromatography. Morphometric analysis was performed on skin biopsy specimens to determine correlation between inflammatory cells and peak tissue enrofloxacin concentration on day 1. RESULTS: Morphometric analysis revealed high correlation between dermal inflammatory cell count and drug concentration in dogs with pyoderma. CONCLUSIONS: At mean dosage of 5 mg/kg once daily, enrofloxacin tissue concentrations were significantly greater in dogs with pyoderma at 3 hours after pill administration. Enrofloxacin tissue concentration on day 3 at 3 hours after pill administration was 12.4 times the 90% minimum inhibitory concentration of enrofloxacin for Staphylococcus intermedius. CLINICAL RELEVANCE: In dogs with pyoderma, therapeutic tissue concentrations of enrofloxacin are reached as early as 3 hours after drug administration.