Short-term prednisolone therapy has minimal impact on calcium metabolism in dogs with atopic dermatitis.

Glucocorticoids (GCs) are a large group of drugs used to treat a range of inflammatory, autoimmune and neoplastic diseases in dogs. Glucocorticoids have been linked to disturbances in calcium metabolism and skeletal disorders in humans, yet their effects at therapeutically effective dosages in dogs with spontaneous diseases are poorly understood. Serum concentrations of calcium, phosphate, vitamin D metabolites and plasma concentrations of parathyroid hormone and ionised calcium together with urinary fractional excretion of calcium and phosphate, were measured in 16 dogs with atopic dermatitis before and 6 weeks after standard dosage prednisolone treatment (0.93-1.06 mg/kg) every other day after 7 days of treatment with the same dosage once daily. The severity of their physical signs, as assessed by the canine atopic dermatitis extent and severity index version 3 (CADESI-03) and the Edinburgh Pruritus Scale (EPS), decreased in all dogs following prednisolone treatment. There was no significant difference in any of the biochemical parameters measured following prednisolone treatment. This study indicates that prednisolone, used at a therapeutically effective dose, has minimal impact on calcium metabolism in dogs with atopic dermatitis.

Evaluation of a human generic formulation of ciclosporin in the treatment of canine atopic dermatitis with in vitro assessment of the functional capacity of phagocytic cells.

To compare the efficacy, tolerability and safety of a generic formulation of ciclosporin for human beings with prednisone in the treatment of canine atopic dermatitis), human generic ciclosporin A (hgCsA) (5 mg/kg daily) and prednisone (1 mg/kg daily for seven days, followed by 1 mg/kg every second day) were administered to 13 and seven dogs with atopic dermatitis, respectively, for 42 days. Skin changes were assessed using a modified canine atopic dermatitis extent and severity index (mCADESI-01) and a pruritus intensity scale system. The in vitro functional capacity of phagocytic cells was assessed using the tetrazolium reductase activity and zymosan-stimulated tetrazolium reductase activity tests, as well as measurements of the percentage phagocytic activity and the ingestion capacity of phagocytic cells. Haematological and biochemical parameters were also monitored. There was a greater than or equal to 50 per cent reduction from the baseline in mCADESI-01 scores in 84.6 and 100 per cent of dogs, and a greater than or equal to 50 per cent reduction from the baseline in pruritus scores in 76.9 and 85.7 per cent of dogs, treated with hgCsA and prednisone, respectively. No important adverse physical, haematological or biochemical effects occurred with either drug and no statistically significant changes were detected in any of the four tests assessing the functional activity of phagocytes. The generic formulation of ciclosporin was effective in reducing the severity of physical signs of canine atopic dermatitis and was well tolerated.

Focal metatarsal sinus tracts in a Weimaraner successfully managed with ciclosporin.

Focal metatarsal sinus tracts ('fistulation') are, to the authors knowledge, reported for the first time in a Weimaraner. The six-year-old, entire male had a five-month history of two symmetrical, well-demarcated sinuses on the plantar aspect of each metatarsus. The area surrounding each pair of sinuses was slightly fluctuant and a serosanguineous discharge could be expressed. Cytological examination of the discharge was characteristic of pyogranulomatous inflammation. Bacterial culture showed the material to be sterile. Examination of a skin biopsy revealed a severe inflammatory reaction involving the dermal collagen, with an infiltrate of neutrophils, macrophages, lymphocytes, plasma cells and multi-nucleated giant cells, with some micro-pustule formation. Treatment with ciclosporin induced total remission. Reduction of the dose of ciclosporin resulted in recurrence of the physical signs with further remission on re-introduction of the original dosage. This is the first report of the use of ciclosporin to control this condition.

Immune responses to Staphylococcus aureus and Psoroptes ovis in sheep infected with P. ovis--the sheep scab mite.

In sheep, lesions caused by Psoroptes ovis, the sheep scab mite, may become colonized by Staphylococcus aureus. The present study compares clinical signs, lesional area and the immune response to P. ovis and S. aureus in P. ovis-infested sheep with and without secondary S. aureus infection. No differences were detected in the clinical signs or lesional areas in the S. aureus-positive and -negative sheep. However, 6 weeks after infestation an IgG but not IgE isotype antibody response to S. aureus was detected in the S. aureus-positive but not the S. aureus-negative group of sheep. This response targeted S. aureus antigens with molecular weights of approximately 36, 38, 50 and 65 kDa. In addition, 6 weeks after infestation an IgE response to P. ovis was detected in the S. aureus-positive but not the S. aureus-negative group of sheep.

Characterisation of lesional infiltrates of dendritic cells and T cell subtypes during primary infestation of sheep with Psoroptes ovis, the sheep scab mite.

Earlier studies of cattle and sheep have demonstrated that Psoroptes ovis infestations provoke an intense immunoinflammatory response dominated by eosinophils accompanied by a substantial infiltrate of lymphocytes. However, the kinetics of the lymphocyte response and the subtypes involved have not been characterised. We employed two groups of sheep to investigate the early (1-21 days) and later (21-63 days) infiltration of lymphocyte subpopulations and dendritic cells in primary infestations of sheep with P. ovis. Immunohistochemistry indicated that by 4 days after infestation numbers of CD4+ and CD45RA+ cells in lesional skin had increased significantly (P<0.03 and P<0.005, respectively) and that a significant increase in gammadelta T cells and dendritic cells (CD1b+) had occurred by 8 days (P<0.02 and P<0.01, respectively). Numbers of lymphocyte and dendritic cells declined from 49 to 63 days after infestation. Our observations suggest that mite-derived products exert a profound influence on the early recruitment of lymphocytes that may significantly influence the genesis of the adaptive immune response.

Early innate and longer-term adaptive cutaneous immunoinflammatory responses during primary infestation with the sheep scab mite, Psoroptes ovis.

Clinical observation has indicated that Psoroptes ovis mites provoke cutaneous inflammation within hours of experimental infestation, but the nature of this reaction has not been described. After infestation of naive sheep with ovigerous P. ovis mites, significant influxes of eosinophils (P<0.004) and neutrophils (P<0.001) were detected within 24 h. A significant (P<0.001) increase in mast cell numbers was observed by 96 h post-infestation. In addition, marked degenerative and proliferative epidermal lesions were evident 24 and 96 h, respectively, after infestation. The influence of the later, adaptive response on the cellular infiltrate at the advancing margin of the lesion and the original site of infestation was also monitored. Mast cell numbers were greatest at 21 days while recruitment of eosinophils and neutrophils was maximal 63 days after infestation. Lesional severity was particularly pronounced from 42 to 63 days after infestation, but significant resolution had occurred by 84 days. Pathological changes at the advancing margin of the lesion were more severe than at the initial site of infestation, and this was reflected by the numbers of mites present. These data suggest that P. ovis elicits an early innate cutaneous response that is subsequently augmented by the development of an adaptive immune response, the intensity of which corresponds to the local population density of mites.

Dermatitis and lymphadenitis resembling juvenile cellulitis in a four-year-old dog.

A four-year-old, entire male toy poodle was presented with a two-and-a-half-week history of ocular discharge progressing to periorbital alopecia, depigmentation, alopecia and ulceration around the muzzle. There was also a haemorrhagic discharge from the ears, pyrexia, lethargy and generalised lymphadenopathy. The clinical, cytological, bacteriological and histopathological findings were consistent with a diagnosis of dermatitis resembling juvenile cellulitis in an adult dog. Glucocorticoid therapy led to rapid resolution of the clinical signs and the dog has remained in remission for two years after cessation of treatment.

Cutaneous hypersensitivity reactions to Psoroptes ovis and Der p 1 in sheep previously infested with P. ovis--the sheep scab mite.

We have previously shown that infestation with Psoroptes ovis induces an IgE response and intense tissue eosinophilia, typical of a Type I hypersensitivity response [Parasite Immunol. 22 (2000) 407]. Intradermal tests (IDSTs) suggest that there are also delayed and Arthus-type responses to this parasite. In order to study the nature of ovine cutaneous reactions to P. ovis, naïve controls and experimentally infested sheep (n = 5) were challenged intradermally with mite antigen. Challenge elicited immediate (P < 0.001) and delayed (P < 0.005) wheal reactions in sensitised sheep. At 6 (P < 0.02) and 30 h (P < 0.001) the predominant infiltrating cells were eosinophils. To explore the role of circulating antibodies, naïve sheep (n = 5) were subjected to Prausnitz-Kustner (PK) tests. These elicited immediate (P < 0.02) but not delayed wheal reactions. At 6 h eosinophils (P < 0.001) dominated the infiltrate. These results suggest that P. ovis allergens provoke an IgE-dependent immediate and late phase response and a cell-mediated eosinophil-rich delayed-type hypersensitivity response (ER-DTH).

Temporal pattern of isotype-specific antibody responses in primary and challenge infestations of sheep with Psoroptes ovis--the sheep scab mite.

In sheep Psoroptes ovis provokes an allergic dermatitis with significant P. ovis antigen-specific IgE responses. The kinetics of the IgE response to primary and challenge infestations of P. ovis were reported earlier [Parasite Immunol. 22 (2000) 407]. The present study examines IgG, IgM and IgA responses to primary and challenge infestations of P. ovis and the profile of antigens/allergens reacting with IgG and IgE antibodies. Antigen-specific enzyme-linked immunosorbent assays (ELISAs) demonstrate that primary infestations elicited significant increases in levels of IgG and IgM but not IgA antibodies. IgG and IgM responses to primary and challenge infestations were not significantly different. Western blots of reduced P. ovis proteins indicate that IgG antibodies reacted with five major antigens following primary infestation and only three of these after challenge infestation. IgE antibodies bound to three major and five minor allergens after primary infestation and two additional minor allergens after challenge infestation. Immunodominant antigens >100 and <15 kDa and allergens >100 kDa were most consistent in stimulating substantial IgG and IgE antibody responses, respectively. These antigens/allergens may be exploited in immunodiagnosis and modulation of the host immune response.

Identification of an antigen from the sheep scab mite, Psoroptes ovis, homologous with house dust mite group I allergens.

Infestation of sheep with the ectoparasitic mite Psoroptes ovis, results in a severe allergic dermatitis. Currently, little is known about the allergens/antigens that stimulate the allergic response. We have isolated an 836-bp cDNA from a P. ovis cDNA library which displays strong homology to cysteine proteases and, in particular, to the group I house dust mite allergens Der p 1, Der f 1 and Eur m 1. The cDNA was expressed in Escherchia coli, fused to a hexahistidine tag and the recombinant protein (Pso o 1) purified using a nickel-affinity column. The recombinant Pso o 1 was tested for recognition by immunoglobulin (Ig)G and IgE in serum from P. ovis naïve and P. ovis infested sheep. Using Western blots, both classes of antibody to Pso o 1 were detected in postinfestation serum. In enzyme-linked immunosorbent assays, a pronounced IgG-antibody response to Pso o 1 was detected in five of five sheep 3 weeks postinfestation. The IgE-antibody response to whole mite extract was poor in four of five animals. However, a marked IgE response occurred in the fifth animal, and IgE anti Pso o 1 was detected in the serum.