Effects of cetirizine in dogs with chronic atopic dermatitis: a randomized, double blind, placebo-controlled trial

This study was conducted to evaluate the effects of cetirizine in dogs with atopic dermatitis (AD) while fulfilling Favrot's diagnostic clinical criteria. Dogs received either 3 mg/kg cetirizine (n = 27), or a placebo (n = 23) orally once daily for 14 days in a randomized, double blind, placebo-controlled study, without concomitant medication. The effects were evaluated using a pruritus visual analog scale at the start (day 0) and at day 14. After 14 days, cetirizine clearly had no effect on the pruritus in dogs with chronic AD, and there was no significant difference between groups. These findings indicated that cetirizine (and likely H1 histamine receptor antagonists in general) should not be recommended for the control of pruritus in dogs with long term allergies.

Recombinant Culicoides obsoletus complex allergens stimulate antigen-specific T cells of insect bite hypersensitive Shetland ponies in vitro

BACKGROUND

Ponies may suffer from Insect bite hypersensitivity (IBH), an allergic IgE-mediated pruritic skin disorder, induced by allergens from biting midges of the Culicoides spp.

HYPOTHESIS/OBJECTIVES

To determine whether recombinant Culicoides obsoletus allergens are able to activate T cells of ponies exposed to C. obsoletus and whether these allergen-specific responses differ between IBH-affected and healthy ponies.

ANIMALS

Ten IBH-affected Shetland ponies and 10 age-matched healthy controls taken from the same stables, to ensure similar exposure to midges.

METHOD

Peripheral blood mononuclear cells (PBMC) were cultured with two different pools of recombinant C. obsoletus complex allergens to expand the allergen-specific T cells. These PBMC cultures were subsequently co-cultured with mature dendritic cells (DCs) loaded with the same antigens. Induction of Th1, Th2 and regulatory T (Treg) cells in these DC/PBMC co-cultures was assessed by analysis of IFN-γ, IL-4, IL-10 and FoxP3 expression levels using quantitative RT-PCR and phenotyping by flow cytometry.

RESULTS

Recombinant C. obsoletus allergens increased IFN-γ mRNA expression levels, percentages of IFN-γ expressing (Th1) cells and CD25(high) FoxP3(+) IL-10(+) Tregs compared to unstimulated DC/PBMC co-cultures. Stimulation of IL-4 expressing Th2 cells by the recombinant allergens was far less pronounced. The DC/PBMC co-cultures did not reveal significant differences between healthy and IBH-affected ponies for any of the analysed parameters, except for higher IL-4 mRNA levels in IBH affected ponies after stimulation with one of the two allergen pools.

CONCLUSION AND CLINICAL IMPORTANCE

The recombinant C. obsoletus complex allergens can stimulate antigen-specific Th1 and IL10 producing Treg cells and are therefore promising candidates for the immunotherapy of IBH.

Allergen-Specific Cytokine Polarization Protects Shetland Ponies against Culicoides obsoletus-Induced Insect Bite Hypersensitivity

The immunological mechanisms explaining development of an allergy in some individuals and not in others remain incompletely understood. Insect bite hypersensitivity (IBH) is a common, seasonal, IgE-mediated, pruritic skin disorder that affects considerable proportions of horses of different breeds, which is caused by bites of the insect Culicoides obsoletus (C. obsoletus). We investigated the allergen-specific immune status of individual horses that had either been diagnosed to be healthy or to suffer of IBH. Following intradermal allergen injection, skin biopsies were taken of IBH-affected and healthy ponies and cytokine expression was determined by RT-PCR. In addition, allergen-specific antibody titers were measured and cytokine expression of in vitro stimulated, allergen-specific CD4 T-cells was determined. 24 hrs after allergen injection, a significant increase in mRNA expression of the type-2 cytokine IL-4 was observed in the skin of IBH-affected Shetland ponies. In the skin of healthy ponies, however, an increase in IFNγ mRNA expression was found. Analysis of allergen-specific antibody titers revealed that all animals produced allergen-specific antibodies, and allergen-specific stimulation of CD4 T-cells revealed a significant higher percentage of IFNγ-expressing CD4 T-cells in healthy ponies compared to IBH-affected ponies. These data indicate that horses not affected by IBH, in contrast to the so far established dogma, are not immunologically ignorant but have a Th1-skewed allergen-specific immune response that appears to protect against IBH-associated symptoms. To our knowledge this is the first demonstration of a natural situation, in which an allergen-specific immune skewing is protective in an allergic disorder.

The effect of long-term feeding of skin barrier-fortified diets on the owner-assessed incidence of atopic dermatitis symptoms in Labrador retrievers

We investigated the effect of feeding a skin barrier function-augmenting diet early in dogs' lives on the appearance of clinical signs associated with canine atopic dermatitis. Pregnant bitches (starting 5 weeks after mating) and their subsequent litters (up to 1 year of age) were fed either supplemented or unsupplemented diets. Nutrients supplemented were nicotinamide, pantothenate, histidine, inositol and choline. Circulating IgE levels to dust mute allergens Der f and Der p were measured when the puppies were 6 and 12 months old. Two owner questionnaires were used to assess the occurrence of typical signs associated with atopic dermatitis when dogs were between the ages of 22 and 36, and 34 and 48 months. Using linear mixed models we observed higher levels of circulating anti-Der f (P = 0·021) and -Der p IgE (P = 0·01) during the first year in the dogs fed the unsupplemented than in those fed the supplemented diet. The owner-assessed incidence of atopic dermatitis signs amongst the dogs was significantly greater in the unsupplemented group at the time of the second follow-up questionnaire (10/33 dogs v. 2/24 dogs). These outcomes suggest that a nutritionally derived improvement to barrier function early in life may reduce the frequency of signs associated with atopic dermatitis. The effect is possibly the result of making the epidermis, now thought to be a major route of environmental allergen exposure, more resistant to penetration.

The immunostimulatory effect of CpG oligodeoxynucleotides on peripheral blood mononuclear cells of healthy dogs and dogs with atopic dermatitis

Synthetic oligodeoxynucleotides containing cytosine phosphatidyl guanine-rich DNA sequences (CpG ODN) can promote T-helper type 1 (Th1) responses, reduce T-helper type 2 (Th2) responses and/or favour regulatory T cell (Treg) responses in vitro and in vivo in humans and animals, by acting via Toll-like receptor 9 (TLR9). Since CpG ODN can be used as immune-modulators for canine atopic dermatitis (AD), the aim of the current study was to investigate their immunostimulatory potential on peripheral blood mononuclear cells (PBMC) and their subsets, from AD and healthy dogs. Expression of TLR9 and cytokine mRNA in CpG ODN-stimulated and unstimulated cells was assessed by real-time quantitative PCR. Stimulation of PBMC with CpG class C ODN upregulated mRNA expression of interleukin (IL)-6, interferon (IFN)-γ and IL-12p40 in AD dogs (P<0.05). It also stimulated IFN-γ protein secretion by PBMC of atopic and healthy dogs as measured by ELISA. In healthy dogs only, CpG class C ODN stimulated IFN-α mRNA production by CD21(+) cells, and IL-10, IL-13 and IFN-γ mRNA production by CD3(+) cells. Increased expression of TLR9 mRNA was only observed in CD3(+) cells from AD dogs. No significantly increased gene expression was found in the CD11c(+) subset upon stimulation, for those genes evaluated. The results indicate that PBMC of healthy and atopic dogs are sensitive to stimulation with CpG ODN class C, with a resulting Th1 cytokine response in AD dogs and a mixed Th1/Th2/Treg cytokine response in healthy dogs. From this study, little evidence was found to support the use of CpG ODN class C for therapeutic purposes in dogs affected with AD.

Amphiregulin is essential for UVB mediated immunosuppression. (P6231)

UVB exposure of the skin is associated with amelioration of inflammatory diseases, which has been shown to be mediated by activated Tregs. Since we have recently shown that Tregs, for optimal functioning, are dependent on signals induced by the EGF-like growth factor AREG, we tested whether UVB-mediated immunosuppression is dependent on AREG. We irradiated C57BL/6 wt and AREG-/- mice with UVB light and sensitized them with DNFB. Mice then were challenged and ear swelling was measured. Our results show that UVB light irradiation suppressed ear swelling in wt but not in AREG-/- mice. To determine at what point AREG expression would be essential, we transferred lymphocytes isolated from lymph nodes of irradiated and sensitized wt mice into naïve wt or AREG-/- mice, that then were sensitized with DNFB and challenged. In contrast to wt recipients, AREG-/- mice lacked suppression upon challenge. Similar results were found when lymphocytes, derived from UVB-irradiated CD4cre x EGF-Rflox/flox or wt mice, were transferred into wt mice. Mice that had received lymphocytes from irradiated and sensitized wt mice were fully able to suppress challenge induced ear swelling, while those that had received lymphocytes derived from UVB-irradiated CD4cre x EGF-Rflox/flox showed a significantly decreased ability to suppress swelling. Our data shows that AREG at the site of inflammation is essential for UVB irradiation-induced and Treg mediated immunosuppression.

Tandem repeats modify the structure of the canine CD1D gene

Among the CD1 proteins that present lipid antigens to T cells, CD1d is the only one that stimulates a population of T cells with an invariant T-cell receptor known as NKT cells. Sequencing of a 722 nucleotide gap in the dog (Canis lupus familiaris) genome revealed that the canine CD1D gene lacks a sequence homologous to exon 2 of human CD1D, coding for the start codon and signal peptide. Also, the canine CD1D gene contains three different short tandem repeats that disrupt the expected gene structure. Because canine CD1D cDNA lacks sequences homologous to human exon 2 and 3, the functionality of canine CD1d protein may be affected, and this could have consequences for the development and activation of canine NKT cells.

Two loci on chromosome 5 are associated with serum IgE levels in Labrador retrievers

Crosslinking of immunoglobulin E antibodies (IgE) bound at the surface of mast cells and subsequent mediator release is considered the most important trigger for allergic reactions. Therefore, the genetic control of IgE levels is studied in the context of allergic diseases, such as asthma, atopic rhinitis, or atopic dermatitis (AD). We performed genome-wide association studies in 161 Labrador Retrievers with regard to total and allergen-specific immunoglobulin E (IgE) levels. We identified a genome-wide significant association on CFA 5 with the antigen-specific IgE responsiveness to Acarus siro. We detected a second genome-wide significant association with respect to the antigen-specific IgE responsiveness to Tyrophagus putrescentiae at a different locus on chromosome 5. A. siro and T. putrescentiae both belong to the family Acaridae and represent so-called storage or forage mites. These forage mites are discussed as major allergen sources in canine AD. No obvious candidate gene for the regulation of IgE levels is located under the two association signals. Therefore our studies offer a chance of identifying a novel mechanism controlling the host's IgE response.

Lesional skin in atopic dogs shows a mixed Type-1 and Type-2 immune responsiveness

Canine atopic dermatitis (AD) is a chronic inflammatory and pruritic skin disease which shares several characteristics with its human counterpart. In chronic patch test lesions of human with AD mainly a Th1-type cellular response is found. Besides, non-lesional AD skin is already skewed for inflammation and therefore different from healthy skin. The goal of this study was to characterize local immune responsiveness in chronic canine AD lesions as compared to that in non-lesional AD skin by defining T cell subset relevant cytokine- and transcription factor expression profiles. The gene expression of the Th1 cytokines IL-12p35, IL-12p40 and IFN-γ and their related transcription factors STAT4, SOCS5 and T-bet, the Th2 cytokines IL-4 and IL-13 and transcription factors STAT6, SOCS3 and GATA-3 and the regulatory cytokines IL-10 and TGF-β and the transcription factor FOXP3 was evaluated in healthy control and atopic dogs. In non-lesional (NLS) and chronic lesional skin (LS) of atopic dogs and control skin (CS) from healthy dogs mRNA expression of cytokines and transcription factors were measured by quantitative real-time PCR. Significantly different values were found for the following factors: IL-12p40 mRNA was lower in LS when compared to NLS. Expression of STAT4 was higher in LS compared to CS and NLS. More IL-13 and SOCS3 were found in LS and NLS when compared to CS and also in LS compared to NLS. GATA-3 was lower in LS compared to NLS. IL-10 expression was higher in both LS and NLS compared to CS and more IL-10 was present in LS compared to NLS. These findings indicate that both Th1- and Th2-type as well as T regulatory cells are present in NLS and LS in canine atopic skin.

Allergen and endotoxin exposure in a companion animal hospital

BACKGROUND

Exposure to allergens, both in general and occupational environments, is known to result in sensitisation and exacerbation of allergic diseases, while endotoxin exposure might protect against allergic diseases. This may be important for veterinarians and co-workers. However, exposure levels are mostly unknown.

OBJECTIVE

We investigated the allergen and endotoxin exposure levels of veterinary medicine students and workers in a companion animal hospital.

METHODS

Airborne and surface dust was collected using various sampling methods at different locations. Allergen levels in extracts were measured with sandwich ELISAs and/or the multiplex array for indoor allergens (MARIA). Endotoxin was determined by limulus amebocyte lysate (LAL) assay.

RESULTS

Fel d 1 (Felis domesticus), Can f 1 (Canus familiaris) and endotoxin were detected in all except stationary samples. The geometric mean (GM) level of personal inhalable dust samples for Fel d 1 was 0.3 ng/m(3) (range: below lower limit of detection (<LOD) to 9.4), for Can f 1 3.6 ng/m(3) (<LOD to 73.3) and for endotoxin 4.4 EU/m(3) (<LOD to 75). Exposure levels differed significantly between job titles, with highest allergen exposure for student assistants in the intensive care unit (Fel d 1, GM 1.5 ng/m(3); Can f 1, GM 18.5 ng/m(3)), and highest endotoxin exposure for students (GM 10.1 EU/m(3)). Exposure levels in dust captured by diverse sampling methods correlated with each other (p<0.05).

CONCLUSION

Allergen exposure likely occurs during veterinary practice, with relatively low endotoxin levels. Future research should investigate dose-response relationship between airborne allergen exposure and health effects.

Intradermal injection of Hsp60 induces cytokine responses in canine atopic and healthy skin

The purpose of this study was to investigate the immunoregulatory potential of Hsp60 in the skin of dogs with atopic dermatitis. Three dogs with chronic atopic dermatitis and four healthy dogs were injected intradermally with Hsp60 and phosphate-buffered saline. Biopsies were taken before testing from non-injected control skin, lesional and non-lesional atopic skin, and 48 and 72 h after injection. Analysis of cytokine messenger RNA was performed using quantitative real-time polymerase chain reaction. Forty-eight hours after Hsp60 injection, a rise in interleukin (IL)-10 was found (P = 0.034) with the highest expression levels in non-lesional atopic and control skin. A rise of transforming growth factor beta (P = 0.015) and IL-12p40 (P = 0.017) was noticed 72 h after Hsp60 injection in control skin. No significant differences were observed for the expression of IL-4, IL-12p35, and interferon gamma. The results indicate that Hsp60 is able to induce cytokines of a regulatory and Th1 phenotype in the skin. Furthermore, this study seems to provide a first indication of deficient Hsp60 response in atopic dermatitis affected skin.

Localised pyogranulomatous dermatitis due to Mycobacterium abscessus in a cat: a case report

A case of pyogranulomatous dermatitis, caused by Mycobacterium abscessus, an unusual opportunistic Mycobacterium spp., is described in a cat. Histopathological examination of the affected skin confirmed the diagnosis and Ziehl-Neelsen staining revealed acid-fast rods. A rapidly growing mycobacterium was found after culture on a Löwenstein-Jensen medium. Real-time polymerase chain reaction for the 16S rDNA (434bp) sequence and the sequence of the rpoB gene (359bp) revealed 99% and 100% matches, respectively, with M. abscessus. This is the first report of a feline infection caused by this organism in Europe.

House dust and forage mite allergens and their role in human and canine atopic dermatitis

This article reviews the literature regarding the role of house dust and forage mite allergens in canine atopic dermatitis. The presence of immunoglobulin E (IgE) to these mites, especially to Dermatophagoides farinae, is common in both normal and atopic dogs. Exposure of dogs to the different mites is described both in the direct environment and in the coat of animals for house dust mites and in the food for forage mites. Allergens causing allergic disease in dogs seem to be different from those in humans. Dogs seem to react to high molecular weight allergens, compared to the low molecular weight group 1 and group 2 proteases that are commonly implicated in humans with atopic diseases. Despite numerous published studies dealing with this subject, a number of questions still need to be addressed to better understand the exact role of these mites in the pathogenesis of canine atopic dermatitis and to improve the quality of the allergens used in practice.

Non-pruritic granuloma in Norwegian forest cats

The eosinophilic granuloma complex is a group of skin disorders common in cats. This paper describes the clinical, haematological and histopathological features of 17 related Norwegian forest cats, six of which had a linear granuloma on the caudal thigh, three of which also had a granuloma on the lower lip, and one of which had a granuloma in combination with an indolent ulcer. The high prevalence of the disease in this population is suggestive of a genetic background.

Immunophenotyping of the cutaneous cellular infiltrate after atopy patch testing in cats with atopic dermatitis

Cats with spontaneously occurring atopic dermatitis have clinical and immunocytochemical characteristics compatible with these in humans with atopic dermatitis (AD). The atopy patch test (APT) has proven to be a valuable tool in elucidating the disease process in humans. Additionally, the APT is very specific and bypasses the problem of conflicting results due to differences in chronicity of lesions of AD patients. We adapted the APT for use in cats to explore the suitability of the APT as a tool to study the onset of allergic inflammation in cats with atopic dermatitis. APT were performed in AD cats (n = 6) and healthy cats (n = 10). All cats were patch tested with two allergens in three different dilutions and a diluent control. The allergens for the APT were selected from positive intradermal test and /or prick test results and consisted of: Dermatophagoides farinae, D. pteronyssinus, Tyrophagus putrescentiae, and a grass pollen mixture. APT were read after 10, 24 and 48 h, and punch biopsies for immunohistochemical evaluation were collected at these time points. Macroscopically positive APT reactions were observed in three out of six cats at 24 and/or 48 h with allergen concentrations of 25,000 and 100,000 NU/ml. Reactions were not observed at negative control sites and neither in control animals. A significantly increased number of IL-4+, CD4+, CD3+, MHC class II+ and CD1a+ cells was found in one AD cat with positive APT reactions. Five out of six AD cats had significantly increased IL-4+ T cell numbers at 24 and/or 48 h. Our data indicate that in cats, macroscopically positive patch test reactions can be induced, which have a cellular infiltrate similar to that in lesional skin. We found a high specificity and a macroscopically positive APT reaction in half of the cats, which is similar to what is seen in humans. Hence, the APT in cats might be a useful tool in studying the immunopathogenesis of feline atopic dermatitis.

Mast Cells and Eosinophils in Feline Allergic Dermatitis: A Qualitative and Quantitative Analysis

Mast cells (MCs) and eosinophils are prominent in the perivascular infiltrate of cats with allergic dermatitis. In the skin of allergic cats MCs were mainly observed diffusely in the superficial dermis, while eosinophils were found mainly in the deep dermis in a perivascular pattern. MC counts were significantly higher in cats with allergic dermatitis (P < 0.05) than in healthy control cats, but the number varied widely. Moreover, the numbers of eosinophils in the skin of allergic and control cats differed significantly (P < 0.05) none being found in the latter. There was no significant correlation between numbers of mast cells and eosinophils in the same biopsy sample. In the allergic cats, a significantly lower number of MCs was detected by staining for tryptase than by staining for chymase or by Astra blue staining. Additionally, the chymase: tryptase ratio in healthy cats was reversed in cats with allergic dermatitis. These changes were observed in lesional and nonlesional skin of cats with allergic dermatitis. The findings indicate a generalized effect on MCs in allergic dermatitis. In addition, eosinophils are an important indicator of allergic dermatitis.

Familial footpad hyperkeratosis and inheritance of keratin 2, keratin 9, and desmoglein 1 in two pedigrees of Irish Terriers

OBJECTIVE

To investigate the possibility that variants in the acidic or basic keratin genes or in desmoglein 1 may cause the clinical manifestation of familial footpad hyperkeratosis in Irish Terriers.

ANIMALS

11 dogs belonging to 2 related affected pedigrees of Irish Terriers.

PROCEDURE

Genomic DNA was extracted from blood samples obtained from each dog. The DNA markers linked to the genes keratin 2, keratin 9, and desmoglein 1 were amplified by use of a polymerase chain reaction technique, and length of the products was determined by use of an automatic DNA analyzer.

RESULTS

All tested markers yielded information. None of the markers (genotype) cosegregated with the clinical status of the dogs (phenotype) in the 2 pedigrees.

CONCLUSIONS AND CLINICAL RELEVANCE

Mutations in the genes encoding keratin 2 and 9 as well as desmoglein 1 are highly unlikely to be the primary cause of familial footpad hyperkeratosis in Irish Terriers.

Evaluation of skin test reactivity to environmental allergens in healthy cats and cats with atopic dermatitis

OBJECTIVE

To evaluate skin test reactivity to environmental allergens in healthy cats and in cats with atopic dermatitis (AD).

ANIMAL

10 healthy cats and 10 cats with AD.

PROCEDURE

10 allergens in serial dilutions were injected ID on the lateral aspect of the thorax of sedated cats. Histamine (0.01% solution) and buffer solutions were used as positive and negative controls, respectively. Immediately after the last injection, 10% fluorescein solution was administered IV. Skin test results were evaluated with ultraviolet light after 15 to 30 minutes and at 4 and 6 hours by 2 independent observers. In the control group, skin tests were repeated after 6 weeks. Skin test reactivity and the nature of the immunoglobulin involved were investigated by use of the Prausnitz-Küstner test with untreated and heat-treated cat sera.

RESULTS

Intertest and interobserver agreement were high when measurement of the diameter of the fluorescent wheal was used to evaluate skin test responses, compared with assessment of its intensity. In both groups of cats, immediate skin test reactivity was observed as an IgE-mediated reaction, as an IgG-mediated reaction, and as a result of nonspecific mast cell degranulation. There was no correlation between allergen concentration and the type of reaction observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Skin test reactivity in cats should be evaluated after IV administration of 10% fluorescein solution by means of a Prausnitz-Küstner test to differentiate among IgE-mediated, IgG-mediated, and nonspecific reactions.

Double-blind evaluation of two commercial hypoallergenic diets in cats with adverse food reactions

The aim of this study was to evaluate two commercially available selected-protein-source diets as maintenance diets in cats with dermatological manifestations of adverse food reactions. Twenty cats with a confirmed adverse food reaction were tested in a double-blind manner. An adverse food reaction was diagnosed when, after recovery with a home-cooked elimination diet, the signs relapsed after a challenge with their previous dietary components, and re-disappeared on a second elimination diet period. Hereafter the cats were blind and randomly challenged with two commercial hypoallergenic diets. Relapse of the clinical signs was seen in eight cats (40%) on a lamb and rice diet and in 13 cats (65%) on a chicken and rice diet (P>0.05). Neither one of the commercial diets was as effective in controlling the skin problems as the home-cooked elimination diet. The study confirms that commercial hypoallergenic diets are adequate for maintenance.

Immune dysregulation in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease in humans and dogs with comparable clinical features. Comparative studies of immunological events in the pathogenesis of AD may contribute to understanding of the disease in dogs and to development and evaluation of immunomodulatory strategies of relevance to both species.Both allergen-specific as well as non-specific mechanisms contribute to the disease development. AD skin lesions are proposed to be initiated by activation of allergen-specific Th2-type cells, potentially influenced by local cutaneous factors. In the chronic stage of skin lesions reactivity may change into a Th1-type, e.g. driven by eosinophil derived IL-12. Analyses of these processes in course of time were performed in both spontaneous as well as in experimentally induced lesions (i.e. atopy patch test (APT) lesions). In the present paper, the immunological events as reported for human and canine AD are summarized and compared.

Evaluation of Felis domesticus allergen I as a possible autoallergen in cats with eosinophilic granuloma complex

OBJECTIVE

To investigate the role of Felis domesticus allergen I (Feld I) in the pathogenesis of eosinophilic granuloma complex (EGC) in cats.

ANIMALS

7 healthy cats and 6 cats with EGC.

PROCEDURE

Epidermis was removed from 4 areas. Rubber stoppers filled with Feld I, saline (0.9% NaCl) solution, and PBS solution were glued to the skin lesions and removed 48 hours later. Fluid within each stopper was collected. Biopsy specimens were obtained at each site, snap frozen, and stored at -70 C. Total and differential numbers of cells in fluid were counted. Biopsy specimens were stained by use of monoclonal antibodies against feline CD4, CD8 and CD3. Data were analyzed by use of multivariate repeated-measures analysis.

RESULTS

Healthy cats had a significant increase in number of CD3+ cells, compared with number of CD4+ and CD8+ cells, and Feld I caused a significant increase in number of CD3+ cells, compared with PBS or saline solutions. Cats with EGC had a significant increase in number of CD3+ cells, compared with number of CD4+ and CD8+ cells, and Feld I caused a significant increase in number of CD3+ and CD4+ cells, compared with PBS or saline solutions. Cats with EGC had an increased CD4+ response, a significantly decreased CD8+ response, and a significantly increased CD4-to-CD8 ratio compared with healthy cats.

CONCLUSIONS AND CLINICAL RELEVANCE

The increased CD4+ response, significantly decreased CD8+ response, and significantly increased CD4-to-CD8 ratio are comparable to results in atopic people and allergic cats. Therefore, Feld I could be an autoallergen responsible for chronic inflammatory reactions in cats with EGC.

Interleukin 4-producing CD4+ T cells in the skin of cats with allergic dermatitis

Lesional skin of cats with allergic dermatitis has a cellular infiltrate and a CD4/CD8 ratio comparable to that in humans with atopic dermatitis. CD4+ helper T cells and in particular cells belonging to the Th2 subset play an important role in disease pathogenesis in humans. We investigated the cytokine pattern of CD4+ T cells in situ, with special emphasis on the putative presence of cells producing interleukin 4 (IL4), in cats with allergic dermatitis. Immunohistochemical procedures were used to determine that CD4+ T cells in lesional and nonlesional skin of cats with allergic dermatitis can produce IL4, as occurs in humans. Lesional and nonlesional skin of cats with allergic dermatitis had significantly more IL4+ T cells (P = 0.001) than did skin of healthy control cats. Double staining indicated that all IL4+ cells were positive for pan-T or CD4 markers. Double labeling for mast cell chymase and IL4 stained primarily different cells. Western blotting demonstrated cross-reactivity between the antibody against human IL4 and a feline recombinant IL4. These results indicate that IL4 is primarily produced by CD4+ T cells and is also present in clinically uninvolved skin, indicating a role in the pathogenesis of allergic dermatitis in cats.

Evaluation of selected-protein-source diets for management of dogs with adverse reactions to foods

OBJECTIVE

To evaluate 3 commercially available selected-protein-source diets as maintenance diets in dogs with pruritus caused by adverse food reactions.

DESIGN

Randomized crossover trial.

ANIMALS

40 dogs > 6 months of age with pruritus caused by adverse reactions to foods.

PROCEDURE

Diagnosis was confirmed by use of diet elimination and provocation studies. Subsequently, dogs were fed 3 commercial diets for 3 weeks each in a randomized, blinded, crossover trial. Dogs were evaluated for pruritus, vomiting, diarrhea, and flatulence.

RESULTS

Pruritus recurred in 52.5% of dogs fed a chicken-rice diet, 47.5% of dogs fed a catfish-rice diet, and 85% of dogs fed a venison-rice diet. Overall 95% of the dogs could be managed successfully with at least 1 of the 3 diets.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that commercially available limited-allergen diets with selected protein sources may be appropriate for long-term management of pruritus caused by adverse food reactions. Testing of various protein sources is usually required.

Increased numbers of CD4+ and CD8+ T cells in lesional skin of cats with allergic dermatitis

The aim of this study was to characterize T cells in the skin of cats with an allergic dermatitis histologically compatible with atopic dermatitis, since T cells play an important role in the pathogenesis of atopic dermatitis in humans. We observed a significantly greater number of T cells in lesional skin of domestic short-haired cats with allergic dermatitis (n = 10; median age 5.8 years) than in the skin of healthy control animals (n = 10; median age 5.0 years). In the skin of the healthy control animals, one or two CD4+ cells and no CD8+ cells were found. A predominant increase of CD4+ T cells and a CD4+/CD8+ ratio (mean +/- SD: 3.9 +/- 2.0) was found in the lesional skin of 10 cats with allergic dermatitis. The CD4+/CD8+ cell ratio in the skin of healthy control animals could not be determined because of the absence of CD8+ cells. The CD4+/CD8+ cell ratio in the peripheral blood of 10 cats with allergic dermatitis (mean +/- SD: 1.9 +/- 0.4) did not differ significantly from that in 10 healthy control animals (2.2 +/- 0.4). The CD4+/CD8+ cell ratio and predominance of CD4+ T cells in the lesional skin of cats with allergic dermatitis is comparable to that found in atopic dermatitis in humans. In addition, the observed increase of CD4+ T cells in the nonlesional skin of cats with allergic dermatitis compared to the skin of healthy cats is similar to what is seen in humans. Cytokines produced by T cells and antigen-specific T cells are important mediators in the inflammatory cascade resulting in atopic dermatitis in humans. This study is a first step to investigate their role in feline allergic dermatitis.

A case of Ehlers-Danlos-like syndrome in a rabbit with a review of the disease in other species

A case of marked skin fragility in a 4-month-old pet rabbit is described. The clinical findings, gross pathology, histopathology, and ultrastructure of skin samples were consistent with Ehlers-Danlos-like syndrome. This syndrome is recognized in many animal species and is often compared to Ehlers-Danlos syndrome in humans. Ehlers-Danlos-like syndromes in animals are reviewed and possible similarities between these disorders and Ehlers-Danlos syndrome in humans are discussed.

Feline atopic dermatitis. A model for Langerhans cell participation in disease pathogenesis

Atopic dermatitis is a disorder characterized by cutaneous exanthemata as a consequence of exaggerated eczematous reactions to topical and systemic allergens. Langerhans cells, expressing CD1a and HLA-DR, and dermal dendritic cells, expressing HLA-DR, are known to be potent antigen-presenting cells and are thought to play an important role in the pathogenesis of atopic dermatitis. The immunophenotype of lesional skin in atopic dermatitis in humans involves increased numbers of CD1a+/MHC class II+ dendritic cells in addition to activated T cells, mast cells, and macrophages. To establish feline skin as a model for the study of human atopic dermatitis, and to elucidate the role of dendritic cells in feline atopic dermatitis, we investigated the presence of CD1a+ cells and MHC class II+ cells in the epidermis and dermis of lesional feline skin and in skin of healthy control animals. Immunohistochemistry revealed that MHC class II+ epidermal dendritic cells were CD1a+ in normal feline skin and significantly increased numbers of CD1a+ cells and MHC class II+ cells were present in the epidermis and dermis of lesional skin. These data provide the first correlative documentation of CD1a expression by feline dendritic cells containing Birbeck granules, and indicate the utility of feline skin in the study of human cutaneous atopy.

Leukocyte mobilization to skin lesions, determination of cell surface receptors (CD11b/CD18) and phagocytic capacities of neutrophils in dogs with chronic deep pyoderma

A suction blister technique was used in eight dogs with chronic deep pyoderma to determine chemotaxis in vivo. By flow cytometry the expression of adhesion molecules (CD11b/CD18) on exudative and peripheral neutrophils were analyzed in 11 healthy dogs and six dogs with chronic deep pyoderma. Phagocytosis in vitro capacities of exudative and peripheral neutrophils were analyzed in six healthy dogs and six dogs with chronic deep pyoderma. Dogs with chronic pyoderma showed significantly better chemotaxis in vivo compared with the healthy dogs (P < 0.05). Expression of adhesion molecules CD11b and CD18, and phagocytosis was significantly (P < 0.05) better in the dogs with pyoderma compared with the healthy dogs. In both groups exudative cells expressed significantly (P < 0.05) more CD11b/CD18 receptors compared with blood neutrophils. We conclude that there are no serious functional disturbances detectable in the peripheral neutrophils, nor in the exudative neutrophils from dogs with chronic deep pyoderma.

Immunophenotyping of skin-infiltrating T-cell subsets in dogs with atopic dermatitis

Atopic dermatitis in dogs has many clinical features that are identical to those of the same disorder in man. To investigate the pathogenesis of this disease in dogs and the possibility of similarities to the pathogenesis in humans we compared the presence and ratio of CD4+ and CD8+ T-cells in the cutaneous infiltrate of lesional and non-lesional skin of atopic dogs with that in the skin of healthy dogs. In ten dogs with atopic dermatitis and ten healthy dogs the skin was biopsied at the predilection sites for atopic dermatitis and histological sections were immunohistochemically stained for CD4 and CD8. The staining showed an increase in CD4+ and CD8+ T-cells in canine lesional atopic skin, with a predominance of CD4+ T-cells in the epidermis. In non-lesional atopic skin there was also an infiltration with CD4+ and CD8+ T-cells, but without predominance of CD4+ T-cells. The results in the separate predilection sites did not differ substantially from the mean results. These observations indicate further similarities in the immunopathogenesis of atopic dermatitis in dogs and humans, which may have consequences for the control of atopic dermatitis in dogs and contributes to a possible role of the dog as a model for human atopic dermatitis.

The significance of reactions to purified fractions of Dermatophagoides pteronyssinus and Dermatophagoides farinae in canine atopic dermatitis

The significance of reactions to crude extracts and purified fractions of the house dust mites Dermatophagoides pteronyssinus (Der p I and Der p II) and Dermatophagoides farinae (Der f I and Der f II) was evaluated in dogs with clinical manifestations of atopic dermatitis (AD). In 13 healthy control dogs and eight dogs with AD, immediate skin test reactivity was determined to serial dilutions of Der p I, Der p II, Der f I and Der f II. In addition, allergen-specific IgGd antibodies were determined by means of an enzyme-linked immunosorbent assay (ELISA) and Western blots. The results suggest that, in contrast to what occurs in humans and despite immediate skin test reactivity in some dogs, Der p I, Der p II, Der f I and Der f II are unlikely to be major allergens in dogs with AD. However, only serum of atopic dogs consistently binds a 90 kDa polypeptide of D. farinae, as shown by Western blot analysis.

Demodicosis in ferrets (Mustela putorius furo)

This report describes the clinical signs, diagnosis, and therapy of demodicosis in ferrets. Two ferrets (Mustela putorius furo) were presented with a history of local alopecia and pruritus after repeated treatment with a glucocorticoid-containing ointment for recurrent ear mite infections. Skin scrapings and biopsies revealed adult mites and larvae of Demodex spp., which were measured according to current classification techniques. Treatment with amitraz was effective and did not cause noticeable side effects. To the authors' knowledge this is the first report of demodicosis in ferrets.

Immunoglobulin concentrations in nasal lavage fluids in dogs with non-specific rhinitis

The pathophysiology of non-specific chronic rhinitis(NSCR) in dogs is still unknown. In this study the possible role of immunological mechanisms in NSCR is examined, by comparing immunoglobulin concentrations in nasal lavage fluids of dogs with NSCR with those of healthy dogs. The immunoglobulin IgA was detected in nasal lavage fluids of both groups of dogs and the differences in relative levels of IgA in dogs with NSCR were not significant. IgM, IgG(a,b), and IgG(d) were detected more frequently in dogs with NSCR (P<0.05), and the relative levels were higher. The presence of IgG(a,b) may indicate the chronic character of rhinitis, and the presence of IgG(d) the possibility of an allergic component in its pathophysiology. The role of IgM is not completely clear.

A retrospective evaluation of adverse reactions to trimethoprim-sulphonamide combinations in dogs and cats

Adverse reactions to various trimethoprim-sulphonamide (T-S) combinations were studied retrospectively in dogs and cats referred to the Utrecht University Department of Clinical Sciences of Companion Animals during the period 1985-1994. Dermatological and systemic reactions were observed in 19 dogs and 2 cats. Specific histological reaction patterns were seen in 3 dogs with toxic epidermal necrolysis, in 1 dog and 1 cat with erythema multiforme, and in 1 dog with pemphigus foliaceus. Diagnostic criteria used in humans proved to be reliable in dogs and cats as well. Adverse reactions were observed within 7-14 days after administration and were most often due to sulphadiazine (76%) and sulphatroxazole (14%). The incidence of adverse reactions to T-S was 0.25%.

Cytophilic antibodies in cats with miliary dermatitis and eosinophilic plaques: passive transfer of immediate-type hypersensitivity

Passive cutaneous anaphylaxis test and Praunitz-Küstner tests were performed in healthy recipient cats with heated and unheated sera of 17 cats suspected of having allergic dermatitis and of 12 healthy control cats. Positive reactions occurred with heated and unheated sera. It was therefore hypothesized that a heat-stabile cytophilic antibody is involved in the pathogenesis of eosinophilic plaques and miliary dermatitis in some cats.

Efficacy of daily amitraz therapy for refractory, generalized demodicosis in dogs: two independent studies

In two independent studies, 0.125% amitraz solution applied half-body daily was found 73% effective in curing dogs with demodicosis previously refractory to biweekly or weekly amitraz treatments. Thirteen of the 16 cases that resolved did so after one course of treatment which ranged from four weeks to five months in duration. The other three cases initially relapsed but then were cured after they were re-treated. All cases deemed cured, including those that initially relapsed, were followed for at least one year after their last treatment.

Efficacy of daily amitraz on generalised demodicosis in dogs

Fifty dogs with generalised demodicosis were treated with daily applications of 0.125 per cent amitraz solution over half the body. This was applied once a day, alternating the body half treated. Nine dogs were lost to follow-up; the remaining dogs were classified as either a success (25 dogs, 61 per cent) or a failure (16 dogs, 39 per cent) according to their response to treatment. Eight of the failures were due to persistent demodicosis and eight relapsed within one year after treatment. All eight of the relapsed dogs were cured after a second course of daily amitraz treatment. For the 25 dogs considered treatment successes, the median duration of treatment was 6.5 weeks (range, three weeks to nine months), and the median interval from completion of treatment to last post treatment evaluation was 3.4 years (range, two to four-and-a-half-years). Including the eight dogs that were cured after retreatment, the daily amitraz applications were curative in 33 of 41 dogs (80 per cent) with generalised demodicosis.