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.     

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.     

Sézary syndrome in a cat

Sézary syndrome is an uncommon leukemic variant of cutaneous lymphoma in cats. This cat had recurrent dermatitis with erythematous, pruritic plaques. Multiple skin imprints and biopsy samples were obtained over a 6-month period, and histopathological findings were consistent initially with eosinophilic miliary dermatitis and later with erythema multiforme. One week before death, Sézary cells were identified in the peripheral blood that expressed cluster of differentiation (CD)3 and CD8 antigens. Massive infiltration of CD3+ lymphocytes was noted in the skin and multiple internal tissues by histopathological examination. This case demonstrates the difficulty in diagnosing cutaneous lymphoma early in the disease course.     

Responsiveness and validity of the SCORFAD, an extent and severity scale for feline hypersensitivity dermatitis

Background – Hypersensitivity (allergic) dermatitis (HD) is commonly seen in cats, causing pruritus and various patterns of skin lesions, including at least one of the following: head and neck excoriations, self‐induced alopecia, eosinophilic plaques and miliary dermatitis. Few studies have evaluated the efficacy of therapeutic interventions for feline HD, and although various scales have been considered, none has been formally validated for the assessment of disease severity and its response to therapy. Objective – To design and validate a novel scale (SCORing Feline Allergic Dermatitis; SCORFAD) to assess the value of different criteria used as outcome measures for the treatment of feline HD and to set minimal thresholds for defining the clinical success of tested interventions. Animals – One hundred client‐owned cats. Methods – The SCORFAD scale was designed to include the four most frequently identified lesion types in feline HD (eosinophilic plaque, head and neck excoriations, self‐induced alopecia and miliary dermatitis) across 10 body regions. The extent and severity of each lesion type were graded prior to inclusion and after 3 and 6 weeks in a clinical study to compare the efficacy of two doses of ciclosporin with placebo. Results – The SCORFAD scale was found to exhibit satisfactory content, construct, criterion and sensitivity to change. The percentage reduction in SCORFAD from baseline was determined to be the most valid assessment of clinical response. Inter‐ and intra‐observer reliability was not assessed. Conclusions and clinical importance – The SCORFAD scale is proposed for use as a validated tool for the assessment of disease severity and response to therapeutic interventions in clinical trials for feline HD.     

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.     

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.     

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.

     

Miliary dermatitis in the cat

Miliary dermatitis is a cutaneous response to disease states seen in the cat. It is not in itself a diagnosis. Conditions which may lead to miliary dermatitis lesions can be divided into hypersensitivity disorders, parasitic causes, infections and miscellaneous causes. A thorough investigation frequently leads to a diagnosis which enables specific therapy. Symptomatic, empirical therapy is less satisfactory and may in the long term cause side effects, The single most important cause of miliary dermatitis in the UK and elsewhere in the world is flea-bite hypersensitivity. Other important and increasingly recognised causes include atopy and food hypersensitivity. With determination and a thorough approach to diagnosis the number of idiopathic cases of miliary dermatitis are small.     

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.     

Fatty acid composition of serum lipids in atopic and healthy dogs

Fatty acids are increasingly used in the treatment of canine atopic dermatitis and their beneficial effects are documented in several prospective, controlled studies. Results from recent studies have indicated that atopic dogs have disordered fat metabolism, due to decreased desaturase activity. To further clarify these possible abnormalities, we examined serum fatty acid patterns in dogs with atopic dermatitis and normal controls. Atopic dermatitis was diagnosed according to the diagnostic criteria proposed by Willemse, after elimination of other possible causes of pruritic dermatitis. Both the relative and the absolute amounts of fatty acids in sera were determined by gas chromatography. Differences in the serum fatty acid pattern indicating a reduction in desaturase activity were not detected in atopic dogs when compared with controls.     

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.     

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.     

Detection of feline herpesvirus 1 DNA in skin biopsy specimens from cats with or without dermatitis

OBJECTIVE: To compare detection rates of feline herpesvirus 1 (FHV-1) DNA in skin biopsy specimens from cats with herpetic dermatitis, cats with nonherpetic dermatitis, and cats without dermatitis. DESIGN: Prevalence survey. Animals-5 cats (9 biopsy specimens) with herpetic ulcerative dermatitis, 14 cats (17 biopsy specimens) with nonherpetic ulcerative dermatitis, and 8 cats (21 biopsy specimens) without clinically apparent skin lesions. PROCEDURES: A single-phase PCR assay was used to detect FHV-1 DNA in biopsy specimens. Assay results were compared with results of histologic examination. RESULTS: FHV-1 DNA was detected in all 9 biopsy specimens from the 5 cats with herpetic dermatitis and in 1 of 17 biopsy specimens from the 14 cats with nonherpetic dermatitis, but was not detected in any of the 21 biopsy specimens from the 8 cats without dermatitis. When results of histologic examination were used as the gold standard, sensitivity and specificity of the PCR assay were 100% and 95%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirmed that FHV-1 DNA can be detected in the skin of cats with herpetic dermatitis and suggest that the virus may play a causative role in the disease. In addition, the PCR assay may be useful in confirming a diagnosis of herpetic dermatitis.     

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.     

Assessment of the influence of fatty acids on indices of insulin sensitivity and myocellular lipid content by use of magnetic resonance spectroscopy in cats

OBJECTIVE: To determine whether dietary fatty acids affect indicators of insulin sensitivity, plasma insulin and lipid concentrations, and lipid accumulation in muscle cells in lean and obese cats. ANIMALS: 28 neutered adult cats. PROCEDURE: IV glucose tolerance tests and magnetic resonance imaging were performed before (lean phase) and after 21 weeks of ad libitum intake of either a diet high in omega-3 polyunsaturated fatty acids (3-PUFAs; n = 14) or high in saturated fatty acids (SFAs; 14). RESULTS: Compared with the lean phase, ad libitum food intake resulted in increased weight, body mass index, girth, and percentage fat in both groups. Baseline plasma glucose or insulin concentrations and glucose area under the curve (AUC) were unaffected by diet. Insulin AUC values for obese and lean cats fed 3-PUFAs did not differ, but values were higher in obese cats fed SFAs, compared with values for lean cats fed SFAs and obese cats fed 3-PUFAs. Nineteen cats that became glucose intolerant when obese had altered insulin secretion and decreased glucose clearance when lean. Plasma cholesterol, triglyceride, and non-esterified fatty acid concentrations were unaffected by diet. Ad libitum intake of either diet resulted in an increase in both intra- and extramyocellular lipid. Obese cats fed SFAs had higher glycosylated hemoglobin concentration than obese cats fed 3-PUFAs. CONCLUSION AND CLINICAL RELEVANCE: In obese cats, a diet high in 3-PUFAs appeared to improve long-term glucose control and decrease plasma insulin concentration. Obesity resulted in intra- and extramyocellular lipid accumulations (regardless of diet) that likely modulate insulin sensitivity.     

The Effects of n-3 Fatty Acid Supplementation on Bleeding Time, Plasma Fatty Acid Composition, and In Vitro Platelet Aggregation in Cats

Dietary supplementation with fish and fish oils rich in the n-3 fatty acids eicosapentaenoic acid ( EPA ) and docosahexaenoic acid (DHA) has been shown to alter eicosanoid metabolism and impair platelet function in several species. As an initial step in evaluating the antithrombotic effect of these n-3 fatty acids in cats, purified EPA and DHA were administered daily to 8 clinically normal cats for 2 months. Platelet function was evaluated biweekly by determining mucosal bleeding time and in vitro platelet aggregation parameters. Plasma fatty acid profiles were obtained before fish oil supplementation and at the termination of the study. In spite of significant increases ( P < .0001) in the plasma concentrations of EPA and DHA after n-3 fatty acid supplementation, there were no significant changes in platelet aggregation or bleeding times. Although it is tempting, based on extrapolation of data from other species, to recommend dietary supplementation with fish oil for cats prone to arterial thromboembolism, these results indicate that administration of large doses of purified EPA and DHA once daily does not inhibit platelet function in normal cats and is unlikely to prevent thrombosis in cats with cardiovascular disease. Additional studies are recommended to ascertain whether more frequent administration of these purified n-3 fatty acids or continual feeding of diets high in n-3 fatty acid content will impair platelet function.     

Leukoencephalomyelopathy in cats linked to abnormal fatty acid composition of the white matter of the spinal cord and of irradiated dry cat food

Four outbreaks of leukoencephalomyelopathy in colonies of SPF cats on a long‐term diet of irradiated dry cat food were observed in the Netherlands between 1989 and 2001. As a primary defect in myelin formation was suspected to be the cause of the disease and myelin consists mainly of lipids and their fatty acids, we investigated the fatty acid composition of the white matter of the spinal cord of affected and control cats and of irradiated and non‐irradiated food. The irradiated food had low levels of alpha‐linolenic acid compared to linoleic acid as well as a high total omega‐6:omega‐3 ratio of 7:1 in the irradiated and of 2:1 in the non‐irradiated food. The white matter of the spinal cord showed low levels of linoleic acid and absence of alpha‐linolenic acid in affected cats as well as absence of lignoceric and nervonic acid in both affected and control cats. These abnormalities in fatty acid composition of the white matter of the spinal cord may reflect an increased need for alpha‐linolenic acid as a substrate for longer chain omega‐3 fatty acids to compose myelin and thus indicate a particular species sensitivity to dietary deficiency in omega‐3 polyunsaturated fatty acids, particularly alpha‐linolenic acid in cats. Our findings indicate that abnormalities in fatty acid metabolism in myelin play an essential role in the pathogenesis of this acquired form of leukoencephalomyelopathy in cats.     

Efficacy of selamectin in the treatment and control of clinical signs of flea allergy dermatitis in dogs and cats experimentally infested with fleas

OBJECTIVE: To determine whether treatment with selamectin would reduce clinical signs of flea allergy dermatitis (FAD) in dogs and cats housed in flea-infested environments. DESIGN: Randomized controlled trial. ANIMALS: 22 dogs and 17 cats confirmed to have FAD. PROCEDURE: Animals were housed in carpeted pens capable of supporting the flea life cycle and infested with 100 fleas (Ctenocephalides felis) on days -13 and -2 and on alternate weeks with 10 to 20 fleas. On day 0, 11 dogs and 8 cats were treated with selamectin (6 mg/kg [2.7 mg/lb]). Dogs were retreated on day 30; cats were retreated on days 30 and 60. All animals were examined periodically for clinical signs of FAD. Flea counts were conducted at weekly intervals. RESULTS: Throughout the study, geometric mean flea counts exceeded 100 for control animals and were < or = 11 for selamectin-treated animals. Selamectin-treated cats had significant improvements in the severity of miliary lesions and scaling or crusting on days 42 and 84, compared with conditions on day -8, and in severity of excoriation on day 42. In contrast, control cats did not have any significant improvements in any of the clinical signs of FAD. Selamectin-treated dogs had significant improvements in all clinical signs on days 28 and 61, but in control dogs, severity of clinical signs of FAD was not significantly different from baseline severity at any time. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that topical administration of selamectin, even without the use of supplementary environmental control measures and with minimal therapeutic intervention, can reduce the severity of clinical signs of FAD in dogs and cats.     

Effect of dietary protein quality and essential fatty acids on fatty acid composition in the liver and adipose tissue after rapid weight loss in overweight cats

OBJECTIVE: To examine effects of dietary protein quality (casein [CA] vs corn gluten [CG]) and dietary lipids (corn oil [CO] vs oil blend [OB] rich in long-chain polyunsaturated fatty acids [LCPUFAs]) on fatty acid composition in liver and adipose tissue after weight loss in overweight cats. ANIMALS: 24 ovariohysterectomized adult cats. PROCEDURE: Cats were allowed ad libitum access to a high-quality diet until they weighed 30% more than their ideal body weight. Cats were then randomly assigned to 1 of 4 weight-reduction diets (6 cats/diet) and were fed 25% of maintenance energy requirements per day. Diets consisted of CG-CO, CA-CO, CG-OB, and CA-OB, respectively, and were fed until cats lost weight and returned to their original lean body mass. Liver biopsy specimens and samples of perirenal, subcutaneous, and abdominal fat were obtained and analyzed for fatty acid content. RESULTS: Following weight loss, fatty acid composition of the liver and adipose tissue was primarily affected by protein quality in that cats fed CA had significantly higher percentages of 20:4(n-6) and 22:6(n-3) fatty acids than those fed CG. Cats fed the CG-CO diet had the lowest concentrations of LCPUFAs, suggesting that dietary lipids and protein quality each influence fatty acid composition in tissues. CONCLUSIONS AND CLINICAL RELEVANCE: These data provide direct evidence that dietary protein quality alters fatty acid composition of tissues during weight loss in cats. The fatty acid patterns observed suggest that protein quality may alter fatty acid composition through modulation of desaturase activity.     

Dyslipidemia in obese cats

Obesity is an important endocrine disorder in cats and is a risk factor for diabetes similar to humans. The goal of this study was to examine the effect of long-term obesity and different diets (high protein, and high carbohydrate supplemented with saturated fatty acids or n-3 polyunsaturated fatty acids) on plasma lipids in the fasted and fed states in 12 lean (LEAN) and 12 obese (OBESE) cats with ultracentrifugation, and nuclear magnetic resonance spectroscopy. OBESE had higher plasma non-esterified fatty acids and triglycerides, as well as very-low-density-lipoproteins (VLDL) consisting primarily of medium-sized particles. The concentration of low-density-lipoproteins (LDL) was comparable between the groups, although OBESE had mostly very small, whereas LEAN had mostly large particles. The concentration of high-density-lipoproteins (HDL) was lower in OBESE and consisted primarily of small particles. Plasma triglycerides, and triglycerides and cholesterol in all lipoproteins increased postprandially. Different diets had little effect on lipids. Our results show that long-term obese cats develop similar lipoprotein changes to humans, yet, hypertension and atherosclerosis have not been described in obese cats. This suggests that dyslipidemia alone is not sufficient to induce hypertension and atherosclerosis. Other anti-atherogenic factors may be present in the obese, dyslipidemic cat.