Clinical characteristics and causes of pruritus in cats: a multicentre study on feline hypersensitivity-associated dermatoses

Hypersensitivity dermatitides (HD) are often suspected in cats. Cats with HD are reported to present with one or more of the following patterns: miliary dermatitis, eosinophilic dermatitis, self-induced symmetrical alopecia or head and/or neck excoriations. Previous reports on feline HD included small numbers of animals, took place in geographically restricted areas or did not compare these conditions with other causes of pruritus. The goal of the present study was to analyse 72 parameters covering signalment, clinical, laboratory and treatment characteristics from a large group of pruritic cats from different geographical areas. Of the 502 cats, the following diagnoses were made: flea HD (29% of cases), food HD (12%) nonflea/nonfood HD (20%) and other diseases in which pruritus was a feature (24%). Cats with signs consistent with a HD but which did not complete a food trial were not analysed further (15% of cases). Most cats with nonflea HD exhibited signs compatible with one or more of the four typical lesional patterns, but none of these patterns was found to be pathognomonic for any specific diagnosis. Food HD and nonflea/nonfood HD were found to be clinically undistinguishable. Young adult, purebred and female cats appeared predisposed to nonflea/nonfood HD. As many diagnoses presented with similar lesional patterns, a thorough clinical work-up is required for establishment of a specific diagnosis.     

Establishment of diagnostic criteria for feline nonflea-induced hypersensitivity dermatitis

Hypersensitivity dermatitides (HD) are commonly seen in cats, and they are usually caused by environmental, food and/or flea allergens. Affected cats normally present with one of the following clinical reaction patterns: head and neck excoriations, usually symmetrical self-induced alopecia, eosinophilic skin lesions or miliary dermatitis. Importantly, none of these clinical presentations is considered to be pathognomonic for HD skin diseases, and the diagnosis of HD is usually based on the exclusion of other pruritic diseases and on a positive response to therapy. The objectives of this study were to propose sets of criteria for the diagnosis of nonflea-induced HD (NFHD). We recruited 501 cats with pruritus and skin lesions and compared clinical parameters between cats with NFHD (encompassing those with nonflea, nonfood HD and those with food HD), flea HD and other pruritic conditions. Using simulated annealing techniques, we established two sets of proposed criteria for the following two different clinical situations: (i) the diagnosis of NFHD in a population of pruritic cats; and (ii) the diagnosis of NFHD after exclusion of cats with flea HD. These criteria sets were associated with good sensitivity and specificity and may be useful for homogeneity of enrolment in clinical trials and to evaluate the probability of diagnosis of NFHD in clinical practice. Finally, these criteria were not useful to differentiate cats with NFHD from those with food HD.     

Serum allergen‐specific immunoglobulin E in atopic and healthy cats: comparison of a rapid screening immunoassay and complete‐panel analysis

Feline and canine atopic dermatitis are thought to have a similar immunopathogenesis. As with dogs, detection of allergen‐specific IgE in cat serum merely supports a diagnosis of feline atopy based on compatible history, clinical signs and elimination of other pruritic dermatoses. In this study, a rapid screening immunoassay (Allercept^® E‐Screen 2nd Generation; Heska AG, Fribourg, Switzerland; ES2G) was compared with a complete‐panel serum allergen‐specific IgE assay (Allercept^®; Heska AG; CP) in healthy cats with no history of skin disease and in atopic cats. The latter had no diagnosis of external parasitism, infection, food hypersensitivity or other skin disease explaining their pruritus, and expressed cutaneous reaction patterns typically associated with feline allergic skin disease (head, neck or pinnal pruritus, miliary dermatitis, self‐induced alopecia, eosinophilic granuloma complex). The proportion of cats positive on either the ES2G or the CP assays was not significantly different between the atopic and healthy cat groups. There was, however, strong agreement between the results of the ES2G and CP assay; overall, the two tests were in agreement for 43 of 49 (88%) serum samples. There was also strong agreement when individual allergen groups were evaluated (agreement noted: indoor, 41 of 49 samples; grasses/weeds, 37 of 49 samples; and trees, 41 of 49 samples). These results indicate that although neither test is diagnostic for feline atopic dermatitis, the screening assay is beneficial for predicting the results of a complete‐panel serum allergen‐specific IgE assay in cats.     

Prospective open pilot study on the use of ciclosporin for feline allergic skin disease

OBJECTIVES: To evaluate the efficacy of ciclosporin in cats with allergic skin disease. METHODS: Ten cats with signs of allergic skin disease were administered ciclosporin daily at a dose of 3.6 to 8.3 mg/kg for one month. None of these cats had previously responded to a hypoallergenic diet trial, and all animals had previously been treated with endectoparasiticidal drugs, with no improvement two weeks before entering the trial. On days 0 and 30, owners assessed pruritus with a visual analogue scale, and veterinarians evaluated cutaneous lesions. RESULTS: All the cats had pruritus and erythema, five had alopecia, two had an eosinophilic plaque, one had miliary dermatitis and two had both alopecia and an eosinophilic plaque. Good or excellent improvement was observed in 40 per cent of cats for pruritus, 57 per cent of cats for alopecia and 60 per cent of cats for erythema. A significant decrease in mean scores was observed for pruritus only, while for erythema and alopecia, it was close to being significant (P < 0.052). CLINICAL SIGNIFICANCE: Ciclosporin may be helpful in symptomatically treating signs of feline allergic skin disease. However, it is important to remember that ciclosporin is not licensed for use in cats.     

Measurement of serum immunoglobulin E (IgE) specific for house dust mite antigens in normal cats and cats with allergic skin disease

The purpose of this study was to determine whether cats with allergic skin disease have significant concentrations of serum Immunoglobulin E (IgE) specific for antigens derived from the house dust mites (HDM) Dermatophagoides farinae (DF) and Dermatophagoides pteronyssinus (DP). Enzyme-linked immunosorbent assays (ELISA) were developed for this purpose. Binding of serum allergen-specific IgE was detected via the use of biotinylated Fc-epsilon receptor alpha chain protein (FcvarepsilonRIalpha). Following optimisation of the assay, serum samples from 59 cats with allergic skin disease and 54 clinically normal cats were screened. Results were expressed as ELISA units per ml (EU/ml) compared to a standard curve. Serological findings were correlated with the clinical presentation of affected cats. Cats with symptoms of feline allergic skin disease were grouped as follows: self-induced alopecia without lesions (group 1), papulocrusting dermatitis (group 2), eosinophilic granuloma complex (group 3), papular/ulcerative dermatitis of head and neck/facial dermatitis (group 4), and a combination of symptoms (group 5). Control normal cats comprised the final group (group 6). The Kruskal-Wallis test was used for statistical analysis. There was no significant difference between groups for DF- and DP-specific IgE concentrations with a p-value of 0.875 and 0.705, respectively. Although the FcvarepsilonRIalpha-based ELISA was able to detect house dust mite-specific feline IgE, the presence of this allergen-specific IgE correlates poorly with the presence of clinical manifestations of allergic skin disease. The results of this study question the clinical relevance of house dust mite-specific IgE in feline allergic skin disease.     

Correlation of histologic and immunologic findings in cats with miliary dermatitis

Eighteen cats with miliary dermatitis were evaluated, using skin testing and histology. Sixteen cats had allergic skin disease (14 cats had positive skin-test reactions to flea antigen [two of which were also atopic], one was atopic only, and one was allergic to beef). In the two remaining cats, the cause of miliary dermatitis was not identified. Histologically, 17 of the cats had superficial eosinophilic dermatitis and epidermal spongiosis, crusting, and ulceration, which were compatible with an allergic cause. Four of these cats had concurrent eosinophilic plaques, which histologically resembled miliary lesions. This overlap of plaques with miliary lesions indicated that when plaques and miliary dermatitis are found concurrently, both lesions may be caused by the same allergens.     

P‐67 Characteristics of the 10 most frequent feline skin disease conditions seen in the dermatology clinic at the National Veterinary School of Nantes

Few studies have presented general epidemiologic data in veterinary dermatology. The aim of this study was to analyse feline dermatological cases seen at the National Veterinary School of Nantes. Animals presented to the clinics are systematically examined with a protocol that allows validation in a computerized system. Seventy prospective codified parameters are collected at each visit (habitat, nutrition, lesions and localisation, laboratory procedures, hypothesis/diagnosis). The final diagnosis in dermatology may combine several causes or diseases. The study included 783 cases seen from January 1992 to January 1997. The following results indicate the frequency of primary diagnosis and frequency of association or suspicion, respectively. The ten most frequent dermatoses were: flea infestations (24.1/33.3%), flea bite hypersensitivity (22.3/42.9%), dermatophytoses (9.9/26.2%), Otodectes (11.5/19%), food allergy (2.8/25.2%), miscellaneous hypersensitivities (2.8/10%), atopy (2.4/22.4%), miscellaneous external otitis (2.4/5.6%), superficial pyodermas (1.4/4.7%), and psychogenic alopecia (1.3/4.7%). In total, flea‐associated problems were identified as the primary cause in 46.5% of cases and hypothesized to be associated in 29% of other cases. Feline miliary dermatitis syndrome was seen in 158 cats (20.2%), feline eosinophilic granuloma complex in 76 cats (9.2%), and extensive alopecia in 58 cats (7.4%). Funding: Self‐funded.     

Food allergy in the cat: a diagnosis by elimination

PRACTICAL RELEVANCE: Food allergy is recognized as a cause of non-seasonal dermatologic disease and pruritus in cats, though its exact prevalence remains unknown. Feline food allergy can also be associated with gastrointestinal, neurologic, respiratory and behavioral components. PATIENT GROUP: There are no breed, sex or age predispositions for developing food allergy, though there is some evidence that the Siamese and its crosses may be at increased risk. CLINICAL CHALLENGES: Food allergy cannot be diagnosed simply on the basis of the distribution of pruritus, and many of the dermatologic reaction patterns observed in affected cats, such as miliary dermatitis, eosinophilic granuloma complex and alopecia, may be seen in cats with flea allergy and atopy; in some cases, cats may have concurrent allergic conditions. The only way to definitively diagnose food allergy is to identify a causative food component through a food elimination trial. However, palatability and client compliance can each be a problem; specifically, many owners are unwilling to perform a provocation challenge, which is required to confirm a suspected food allergy. For cats in which the existence of a food allergy is confirmed, a suitable maintenance diet then needs to be fed for the remainder of the patient's life. EVIDENCE BASE: Recent literature has revealed that there is marked variability in the clinical picture, response to treatment and outcome in food-allergic cats. This article reviews published literature and highlights clinically relevant observations pertinent to feline food allergy.     

The Use of Megestrol Acetate in Some Feline Dermatological Problems

Twenty-one cats were treated with megestrol acetate because they were showing clinical signs associated with one of the following problems: eosinophilic ulcer, eosinophilic plaque, neurodermatitis, endocrine alopecia and miliary dermatitis. The dosage schedule was 5 mg orally per day per cat for seven days, then 5 mg every three days for 21 days.

In all cats, we noted a good improvement of the lesions as soon as treatment was started. In 25% of the patients, one treatment schedule was sufficient to control the skin disease for at least 18 months. In the remaining 75%, two treatment schedules and/or a maintenance dosage had to be established.

Side effects encountered were increased appetite, personality changes and depression.

     

Dermatophytosis and papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis) in three Devon Rex cats

PRESENTING SIGNS: Three Devon Rex cats were presented with multiple erythematous papules, occasionally associated with crusting and hyperpigmentation, with a linear distribution on the head, neck, chest and abdomen. One cat also had multifocal alopecia with hyperpigmentation on the dorsum. DIAGNOSIS AND TREATMENT: Clinical and histopathological features were suggestive of papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis). In all cases, dermatophytosis was diagnosed: in cases 1 and 2 there was histopathological evidence of dermatophytosis, while fungal culture was positive for Microsporum canis in cases 2 and 3. In all cats, lesions disappeared following antifungal treatment. CLINICAL SIGNIFICANCE: Papular eosinophilic/mastocytic dermatitis in Devon Rex cats may represent either an atypical presentation of dermatophytosis or a clinical and histological reaction pattern to various diseases, including dermatophytosis and allergic diseases. Clinical differentiation is crucial as there are important implications regarding treatment and, in particular, the use of glucocorticoids, which are contraindicated in cases of dermatophytosis.     

P-69 Efficacy of cyclosporin in the treatment of feline urticaria pigmentosa: two cases

Few studies have presented general epidemiologic data in veterinary dermatology. The aim of this study was to analyse feline dermatological cases seen at the National Veterinary School of Nantes. Animals presented to the clinics are systematically examined with a protocol that allows validation in a computerized system. Seventy prospective codified parameters are collected at each visit (habitat, nutrition, lesions and localisation, laboratory procedures, hypothesis/diagnosis). The final diagnosis in dermatology may combine several causes or diseases. The study included 783 cases seen from January 1992 to January 1997. The following results indicate the frequency of primary diagnosis and frequency of association or suspicion, respectively. The ten most frequent dermatoses were: flea infestations (24.1/33.3%), flea bite hypersensitivity (22.3/42.9%), dermatophytoses (9.9/26.2%), Otodectes (11.5/19%), food allergy (2.8/25.2%), miscellaneous hypersensitivities (2.8/10%), atopy (2.4/22.4%), miscellaneous external otitis (2.4/5.6%), superficial pyodermas (1.4/4.7%), and psychogenic alopecia (1.3/4.7%). In total, flea-associated problems were identified as the primary cause in 46.5% of cases and hypothesized to be associated in 29% of other cases. Feline miliary dermatitis syndrome was seen in 158 cats (20.2%), feline eosinophilic granuloma complex in 76 cats (9.2%), and extensive alopecia in 58 cats (7.4%).
Funding: Self-funded.     

Feline demodicosis: a consideration in the itchy or overgrooming cat

PRACTICAL RELEVANCE: In cats, three species of demodex mites have been identified as causes of demodicosis, which may manifest as pruritus, miliary dermatitis and/or self-induced alopecia. The condition has been recognized in various countries but does seem to show regional preferences. CLINICAL CHALLENGES: Diagnosis of feline demodicosis can be a challenge as mites are not always readily found within scrapings of the skin examined microscopically. One or more species of demodex mite may be involved in an infestation. Furthermore, the condition can be difficult to treat effectively. AUDIENCE: This review is intended as a clinical update for veterinary surgeons in practice who rarely encounter demodicosis.     

Effect of topical application of fipronil in cats with flea allergic dermatitis

OBJECTIVE: To determine whether topical application of a 10% fipronil solution would control signs of flea allergic dermatitis in cats housed under natural conditions. DESIGN: Multicenter open clinical trial. ANIMALS: 42 client-owned cats with flea allergic dermatitis. PROCEDURES: Study cats along with all other cats and dogs living in the same houses were treated with 10% fipronil solution topically on days 0, 30, and 60. Flea counts and clinical assessments were performed on study cats on days 0, 14, 30, 60, and 90. RESULTS: Percentage reductions in geometric mean flea counts on days 14, 30, 60, and 90, compared with day-0 geometric mean count, were 75, 73, 85, and 94%, respectively. Pruritus score was significantly improved at each examination after day 0, and pruritus was reduced or eliminated in 31 of 40 (78%) cats at the final examination. Similarly, scores for severity of miliary dermatitis and alopecia were significantly improved at each examination, except for alopecia score on day 14. Overall treatment efficacy, assessed on day 90, was excellent for 28 (70%) cats, good for 6 (15%), moderate for 3 (7.5%), and poor for 3 (7.5%). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that monthly topical application of fipronil is effective for treatment of flea allergic dermatitis in cats housed under natural conditions.     

A randomized double-blinded placebo-controlled study to evaluate an effective ciclosporin dose for the treatment of feline hypersensitivity dermatitis

Background – Hypersensitivity dermatitides (HD) are frequently suspected in cats, but there are few clinical studies on safe and effective treatments in the published literature. Objectives – To establish a safe and effective dose of ciclosporin in the treatment of feline HD. Animals – One hundred client‐owned cats with feline HD. Methods – Double‐blind study, with cats randomly assigned to receive ciclosporin at either 7.0 mg/kg once daily (n = 33) or 2.5 mg/kg once daily (n = 32) or a placebo (n = 35) for 6 weeks. Results – Mean Total Lesion Scores with 7.0 mg/kg ciclosporin were significantly lower than with 2.5 mg/kg ciclosporin (P = 0.0047) or placebo (P = 0.0003) at study end. Individual Total Lesion Scores improved by >50% in 70% of the 7.0 mg/kg group, compared with 47% in the 2.5 mg/kg group and 23% in the placebo group (P = 0.0006). The investigators’ Global Assessment of Improvement was ‘excellent’ or ‘good’ in 61% of cats treated with 7.0 mg/kg ciclosporin, compared with 47% of cats given 2.5 mg/kg and 23% given placebo. The improvement in Investigator Pruritus Scores was significantly greater in cats treated with 7.0 mg/kg ciclosporin (54%) compared with both 2.5 mg/kg ciclosporin (32%; P = 0.0232) and placebo (21%; P = 0.0063). Mild gastrointestinal disorders were the most common adverse events, but these did not require cessation of therapy. Conclusions and clinical importance – Results suggest that 7.0 mg/kg ciclosporin once daily in food or per os for 6 weeks is effective and well tolerated in feline HD.     

Feline superficial pyoderma: a retrospective study of 52 cases (2001-2011)

Background – Superficial pyoderma is traditionally considered rare in cats but may be more prevalent than previously reported. Objectives – To better characterize superficial pyoderma in cats. Animals – Fifty‐two cats from a dermatology referral population over a 10 year period. Methods – This study was retrospective. Cases were included if neutrophils and intracellular bacteria were reported from surface cytology of skin lesions. Medical records were reviewed for signalment, historical and clinical data, cytology results, primary skin diagnoses and treatment details. Results – Disease prevalence was 20%, with no breed or sex predispositions. The estimated median age of onset was 2 years, affecting 54% of cats by 3 years and 23% after 9 years. Fewer cases presented during winter (15%) compared with other seasons. Skin lesions were typically multifocal, affecting the face (62%), neck (37%), limbs (33%) and ventral abdomen (29%) most commonly. Crusting (83%), alopecia (67%), ulceration/erosion (54%) and erythema (46%) were common lesion types. Pruritus was reported in 92% of cats. Underlying hypersensitivities (confirmed in 60%; suspected in 19%), and atopic dermatitis specifically (confirmed in 48%), were the most frequent primary dermatoses. Cats were treated with a variety of systemic and/or topical antimicrobials. The overall apparent response was considered good in 61% and poor in 27% of cats. Recurrence was confirmed or suspected in 42% of cats. Conclusions and clinical importance – Feline superficial pyoderma was more prevalent in this study population than previously reported. Young cats with hypersensitivities and older cats were more commonly affected, and a variety of lesion types and distributions occurred.     

Management of feline miliary dermatitis by supplementing the diet with essential fatty acids

Of eight cats with miliary dermatitis, six showed a good response to treatment with a dietary supplement of essential fatty acids. The analysis of serum fatty acids revealed significant abnormalities in cats with miliary dermatitis compared with normal cats.     

Use of modified ciclosporin in the management of feline pemphigus foliaceus: a retrospective analysis

Background – Glucocorticoids as sole therapy for pemphigus foliaceus (PF) in cats are not always successful, and it is common to need additional immunomodulating agents to manage the disease. Hypothesis/Objectives – This retrospective study evaluated the use of modified ciclosporin as an adjuvant or sole immunomodulating drug in cats with PF and compared their response to PF cats managed with chlorambucil. Animals – Fifteen client‐owned cats diagnosed with PF that received ciclosporin and/or chlorambucil as part of their treatment and had adequate follow‐up to assess treatment response were evaluated. Methods – Records were reviewed from feline PF patients presented between the years of 1999 and 2009. Cats were divided into two treatment groups: those treated with ciclosporin and those treated with chlorambucil. Most cats in both groups also received concurrent systemic glucocorticoids. Each group contained six patients. Three cats were treated with both medications and are discussed separately. Time to disease remission, remission‐inducing glucocorticoid dose, maintenance or final glucocorticoid dose, disease response and adverse effects were assessed. Results – There was no significant difference in remission times or disease response between groups. All six patients maintained with ciclosporin for PF management were weaned off systemic glucocorticoids, while glucocorticoid therapy was stopped in only one of the six cats receiving chlorambucil. Conclusions and clinical importance – Modified ciclosporin is effective in the management of feline pemphigus foliaceus and is glucocorticoid sparing.     

Retrospective study: the presence of Malassezia in feline skin biopsies. A clinicopathological study

Malassezia spp. dermatitis, a rare disorder in cats, has previously been associated with immune suppression and internal malignancies. This study evaluates the presence and importance of Malassezia spp. in feline biopsy specimens submitted for histopathological examination. Five hundred and fifty haematoxylin and eosin-stained skin biopsy specimens received for histopathological examination between January 1999 and November 2000 were reviewed. Fifteen (2.7%) submissions contained Malassezia organisms in the stratum corneum of the epidermis or follicular infundibulum. Eleven of 15 cats presented with an acute onset of multifocal to generalized skin lesions. All 11 cats were euthanized or died within 2 months of the onset of clinical signs. Seven cats had dermatopathological changes and clinical signs supportive of paraneoplastic alopecia, and three cats had an interface dermatitis suggestive of erythema multiforme or thymoma-associated dermatosis. Histopathological changes were nonspecific in one cat that was euthanized 2 weeks following onset of severe pruritus and alopecia. In three cats, Malassezia spp. were found in localized sites (two chin, one footpads) and appeared inconsequential to their overall health status. One cat had Malassezia spp. in association with cutaneous demodicosis. These findings suggest that Malassezia yeast in dermatopathological specimens from multifocal or generalized lesions should prompt a thorough clinical work-up for internal neoplasia.     

The use of oral cyclosporin to treat feline dermatoses: a retrospective analysis of 23 cases

Limited information is available regarding the use of cyclosporin A (CsA) for the treatment of feline dermatoses. The aim of this retrospective study was therefore to describe the efficacy of CsA for the therapy of eosinophilic granuloma (EG), eosinophilic plaque, indolent ulcer, linear granulomas, idiopathic pruritus and stomatitis. A computer search for feline dermatological cases treated with CsA between 1999 and 2004 was performed. Based on history, clinical signs and laboratory diagnostic tests, it was then possible to divide cases into three groups and to select 23 cats. Seven cats had one or more of the following conditions: EG, eosinophilic plaque, indolent ulcer and/or linear granuloma (group A); eight cats had idiopathic pruritus (group B) and eight cats had plasmacytic stomatitis (group C). Doses ranged from 5.8 to 13.3 mg kg(-1) oral CsA. All cats were monitored, with complete serum blood analysis and physical examination, monthly for a minimum of 6 months. Response to therapy was scored (severity of lesions and pruritus) with a 0-10 visual analogue scale at each visit (day 0, day, 30, day 60, day 90). All cats in groups A and B were cured and were maintained on alternate day therapy. In group C, 4/8 patients went into remission, while remaining cats have a fair to good improvement. Routine haematological and biochemical examination failed to reveal abnormalities related to CsA administration.     

Feline herpesvirus 1-associated facial and nasal dermatitis and stomatitis in domestic cats.

Feline herpesvirus-associated dermatitis has rarely been reported. Recently we documented a unique ulcerative and often persistent facial dermatitis or stomatitis syndrome associated with feline herpesvirus 1. We believe this syndrome is relatively common, with the 10 cases in our series diagnosed between 1996 and 1997. The syndrome is associated with epithelial cell necrosis, eosinophilic inflammation, and intraepithelial herpesvirus inclusion bodies. The prevalence of eosinophilic inflammation and low number of inclusion bodies may lead to the misdiagnosis of allergic dermatitis or a lesion within the eosinophilic granuloma complex group of disorders. Feline herpesvirus 1 can be identified in lesional tissue by PCR methodology. Most of our cases developed under circumstances suggesting reactivation of latent herpesvirus infection, and previous glucocorticoid therapy or stress from overcrowding may have played a role in lesion development. Cats with ulcerative dermatitis, especially of the face and nose, and cats with stomatitis should be evaluated for the presence of feline herpesvirus. Treatment options include surgical excision, topical or systemic antibiotic therapy to treat secondary bacterial infection, and oral alpha interferon.