The effect of a spot-on formulation containing polyunsaturated fatty acids and essential oils on dogs with atopic dermatitis

Recent studies have shown that immunological aberrations and epidermal barrier defects could be important in the pathogenesis of canine atopic dermatitis (CAD) and that oral polyunsaturated fatty acids (PUFAs) might influence the epidermal barrier. The aim of this study was to evaluate the effects of a spot-on formulation containing PUFAs and essential oils on pruritus and lesions caused by CAD. Forty-eight privately owned dogs of different breeds, ages and genders diagnosed with atopic dermatitis were included in a randomized, double-blinded, placebo-controlled, multicentre clinical trial. Dogs were treated with a spot-on formulation containing PUFAs and essential oils or placebo on the dorsal neck once weekly for 8 weeks. Before and after the study, CAD extent and severity index-03 (CADESI-03) and pruritus scores were determined by veterinarians and owners, respectively.There was significantly more improvement in CADESI-03 and pruritus scores in the treatment group than in the placebo group (P = 0.011 and P = 0.036, respectively). Additionally, more dogs improved by at least 50% in CADESI-03 and pruritus scores in the treatment group than in the placebo group (P = 0.008 and P = 0.070, respectively). No adverse reactions were observed. The topical preparation containing PUFAs and essential oils was a safe treatment and beneficial in ameliorating the clinical signs of CAD.     

FC‐30 Presence of dust mites in the environment of dust mite‐sensitized atopic dogs

Dust mites (DM) are the most common offending aeroallergens in atopic dogs. The aim of this study was to compare the DM load of households with atopic dogs (Group A, n = 8) that had positive intradermal test reactions to Dermatophagoides farinae, D. pteronyssinus, Acarus siro, Lepidoglyphus destructor and/or Tyrophagus putrescentiae to the DM load of households with nonatopic dogs (Group B, n = 4) and of nonpet households (Group C, n = 8). Group A dogs presented with perennial pruritus, were free of pathogenic mites and fleas, did not respond to an elimination diet, and fulfilled the diagnostic criteria of atopic dermatitis. All Group B dogs tested intradermally negative and had no dermatological problems. Dust samples were vacuum collected in a standardized fashion from the human (all groups) and dog mattresses (Groups A and B) or from the couch (Group C) four times, once for each season of the year. The presence of DM was assessed with a commercial test (Acarex test) and stereoscopically. At least one DM was found in all Group A houses. The DM load was not significantly different between the seasons or the three animal groups. The sensitivity of the Acarex test was significantly lower than that of stereoscopic examination (P < 0.001). In conclusion, the environmental DM load was similar between atopic and nonatopic dogs, the presence of dogs in a household didn't increase DM numbers, and stereoscopy was more sensitive than the Acarex test for the detection of DM. Funding: Self‐funded.     

Allergic conjunctivitis and conjunctival provocation tests in atopic dogs

Introduction Canine atopic dermatitis (cAD) is a very common disease, but little is known about eye involvement. The conjunctival provocation test (CPT) is used in human to study the ocular response to allergenic stimuli and to evaluate anti‐allergic therapy. To our knowledge it has not been used in dogs. Objectives To evaluate the prevalence of ocular signs in a population of atopic dogs and relate these with clinical cAD scores; and the usefulness of CPT for dust mites in atopic dogs with itchy eyes. Procedures Sixty cAD patients were evaluated for (i) ocular signs of allergic conjunctivitis including conjunctival hyperemia, chemosis, epiphora, ocular discharge, pruritus and corneal involvement, graded 0 to 3 according to severity, and (2) cAD Extent and Severity Index (CADESI‐03). Additionally, CPTs for Dermatophagoides farinae (n = 12) and Dermatophagoides pteronyssinus (n = 12) were performed in sensitized atopic dogs and 24 control dogs. Results Periocular and ocular signs of allergy were present in 60% (36/60) of cases. Conjunctival hyperemia (90%) was the most common sign. Severity of ocular signs was significantly correlated with eye pruritus (r_s = 0.690, P = <0.001) and skin lesions score for head region (r_s = 0.261, P = 0.04). A highly significant difference (P < 0.001, Fisher test) was found in CPTs between the test and the control groups. Conclusion Allergic conjunctivitis signs associated with cAD seem under valuated so these patients would benefit from an ophthalmologic evaluation. Furthermore, we found CPT to be a reliable, easy to perform and safe test for the etiologic diagnosis of allergic conjunctivitis in the dog.     

FC‐36 The use of immunostimulatory bacterial DNA sequences in allergen‐specific immunotherapy of canine atopic dermatitis

The purpose of this study was to evaluate a combination of immunostimulatory bacterial DNA sequences and allergen‐specific immunotherapy for the treatment of canine atopic dermatitis. Seven dogs with nonseasonal atopic dermatitis diagnosed by history, clinical signs and exclusion of differential diagnoses were included. All dogs had been on allergen‐specific immunotherapy for at least 12 months with incomplete responses, were on additional antipruritic therapy and showed residual pruritus. Pruritus was marked by the owner on a visual analogue scale, lesions were determined by a clinician using the Canine Atopic Dermatitis Extent and Severity Index (CADESI), and concurrent medications were recorded before entering the study and after 14 weeks of treatment. Peripheral blood mononuclear cells were isolated and cultured; canine cytokine message for IFNγ, IL‐4, TNF and IL‐10 was quantitated using RT‐PCR. A mixture of allergen extract and liposome‐DNA complexes was injected intradermally at the beginning of the study and after 2, 4, 6, 10 and 14 weeks. CADESI, pruritus and medication scores, and cytokine messages at the beginning and end of the study were compared with a paired t‐test. There were significant improvements in pruritus scores (P = 0.0277). Reductions in medication scores and CADESI were not statistically significant. IL‐4 production decreased significantly (P = 0.0428); decreases in other cytokines were not significant. Although the number of dogs in this pilot study was small, the results warrant further investigation of a combination of immunostimulatory bacterial DNA sequences and allergen‐specific immunotherapy for the treatment of canine atopic dermatitis. Funding: Self‐funded.     

High allergen-specific serum immunoglobulin E levels in nonatopic West Highland white terriers

Human and canine atopic dermatitis (AD) share an association with IgE specific to environmental allergens, but few studies have evaluated serum allergen‐specific IgE in nonatopic dogs. This study compared serum allergen‐specific IgE levels in 30 atopic and 18 nonatopic West Highland white terriers. Atopic dermatitis was confirmed using standard criteria. Nonatopic dogs were over 5 years of age and had no clinical signs or history of AD. Serum allergen‐specific IgE levels were measured with Allercept^® IgE ELISAs using a 48‐allergen Australian panel. Positive reactions were defined as ≥150 ELISA absorbance units. Intradermal tests were performed in 16 atopic dogs, either at the time of or at various times prior to serum collection. In atopic dogs, the most common positive ELISA and intradermal test results were to Dermatophagoides farinae (11 of 30 dogs), but there were no statistically significant correlations between results from the two methods for any allergen. In nonatopic dogs, multiple high‐positive ELISA reactions were reported to 45 of 48 allergens, most commonly D. farinae and Tyrophagus putrescentiae (17 of 18 dogs each). Positive ELISA results in nonatopic dogs were statistically significantly higher than those in atopic dogs for 44 of 48 allergens, including two allergens (D. farinae and Dermatophagoides pteronyssinus) commonly regarded as significant in canine AD. In conclusion, positive allergen‐specific IgE ELISAs were not specific for canine AD, and high allergen‐specific IgE levels were seen in nonatopic dogs. The clinical significance of this and whether it characterizes a protective phenotype is unclear.     

Patch test reactions to house dust mites in dogs with atopic dermatitis

The purpose of this study was to determine the percentage of dogs with spontaneous atopic dermatitis that show a positive patch test reaction to a commercially available 20% house dust mites mixture containing equal parts of Dermatophagoides farinae and Dermatophagoides pteronyssinus in white petrolatum. In addition, we evaluated whether skin reactions induced after the epicutaneous application of house dust mites were clinically and histologically similar to naturally developed skin lesions of dogs with atopic dermatitis. Furthermore, we investigated if the reactions induced by house dust mites were true allergic reactions by comparing them to atopic lesional skin and to patch test reactions induced by an irritant substance (sodium lauryl sulphate). White petrolatum alone and nonlesional skin sites were used as negative controls. Macroscopic and microscopic evaluations of the patch test and control sites were performed in a blinded fashion at 48 and 72 h after patch test application. Microscopic results were evaluated in a qualitative and quantitative manner. A chi‐square test for homogenicity was used for the quantitative analysis to compare the proportion of each dermal inflammatory cell type among positive histopathological tested sites. P values ≤ 0.05 were considered significant. The study included 12 healthy nonatopic dogs and 13 dogs with nonseasonal atopic dermatitis. None of the nonatopic dogs reacted to house dust mites and white petrolatum. Ten (77%) of the 13 atopic dogs reacted macroscopically and histopathologically to house dust mites. Macroscopic reactions induced by house dust mites were characterized by erythema, oedema and papules. The macroscopic reactions induced by house dust mites were identical to lesional skin in 20% of the dogs and identical to reactions induced by sodium lauryl sulphate in 40% of the dogs. Qualitative histopathological findings showed that the reactions induced by house dust mites were similar to atopic lesional skin in 80% of the dogs and were similar to sodium lauryl sulphate in 20% of the dogs. Quantitative analyses showed that the proportion of neutrophils in reactions induced by sodium lauryl sulphate was significantly higher (P < 0.05) compared to house dust mites reactions, which could be a differentiator factor between an allergic and an irritant reaction. These results showed that the epicutaneous application of house dust mites in dogs with atopic dermatitis induced histopathological lesions similar to spontaneous atopic lesions in dogs. Therefore, this study demonstrated that house dust mites penetrated the skin of dogs with atopic dermatitis and induced an inflammatory response that resembled a true allergic reaction. Funding: Small Companion Animal Grant, University of Minnesota.     

Zinc–carnosine and vitamin E supplementation does not ameliorate gastrointestinal side effects associated with ciclosporin therapy of canine atopic dermatitis

Chelated zinc–carnosine and vitamin E [GastriCalm^® (GCM); Teva Animal Health] is marketed as an anti‐emetic supplement for dogs to assist the repair of damaged stomach and intestinal mucosa. The purpose of this prospective, double‐blinded, placebo‐controlled trial was to determine whether GCM reduced the frequency of vomiting, diarrhoea and appetite changes during initiation of ciclosporin (Atopica^®; Novartis Animal Health) therapy for the treatment of canine atopic dermatitis. Sixty privately owned dogs diagnosed with atopic dermatitis were randomly assigned to GCM (n = 30) or placebo (n = 30) groups. All dogs received ～5 mg/kg ciclosporin (range, 3.5–5.8 mg/kg) once daily. Dogs <13.6 kg received half a tablet of GCM or placebo; dogs ≥13.6 kg received one tablet once daily. GastriCalm^® or placebo was administered 30 min prior to eating, and the ciclosporin was administered 2 h after feeding. Owners recorded episodes of vomiting, diarrhoea and appetite changes. Dogs were examined on days 0 and 14. Forty‐one of 60 dogs (68.3%) had at least one episode of vomiting, diarrhoea or appetite change, leaving nine placebo dogs (30%) and ten GCM dogs (33.3%) free of adverse events (AE). Twenty‐seven of 60 dogs (45%) vomited, and 15 of 60 (25%) had diarrhoea. There was no significant difference in episodes of individual AEs, but the placebo group had a significantly lower total AE score (summation of episodes of appetite change, vomiting and diarrhoea; P = 0.022). Small dogs (<6.82 kg) had significantly fewer total AEs in both treatment groups and tolerated ciclosporin better than larger dogs (P < 0.05).     

FC-38 Efficacy of conjugated linoleic acid and black currant seed oil in the treatment of canine atopic dermatitis: a double-blinded, randomized, placebo-controlled study

The purpose of this study was to evaluate a combination of immunostimulatory bacterial DNA sequences and allergen-specific immunotherapy for the treatment of canine atopic dermatitis. Seven dogs with nonseasonal atopic dermatitis diagnosed by history, clinical signs and exclusion of differential diagnoses were included. All dogs had been on allergen-specific immunotherapy for at least 12 months with incomplete responses, were on additional antipruritic therapy and showed residual pruritus. Pruritus was marked by the owner on a visual analogue scale, lesions were determined by a clinician using the Canine Atopic Dermatitis Extent and Severity Index (CADESI), and concurrent medications were recorded before entering the study and after 14 weeks of treatment. Peripheral blood mononuclear cells were isolated and cultured; canine cytokine message for IFNγ, IL-4, TNF and IL-10 was quantitated using RT-PCR. A mixture of allergen extract and liposome-DNA complexes was injected intradermally at the beginning of the study and after 2, 4, 6, 10 and 14 weeks. CADESI, pruritus and medication scores, and cytokine messages at the beginning and end of the study were compared with a paired t -test. There were significant improvements in pruritus scores ( P  = 0.0277). Reductions in medication scores and CADESI were not statistically significant. IL-4 production decreased significantly ( P  = 0.0428); decreases in other cytokines were not significant. Although the number of dogs in this pilot study was small, the results warrant further investigation of a combination of immunostimulatory bacterial DNA sequences and allergen-specific immunotherapy for the treatment of canine atopic dermatitis.
Funding: Self-funded.     

FC‐39 Successful management of canine atopic dermatitis using a plant extract: a randomized,double‐blinded,placebo‐controlled trial

This study evaluated the efficacy of Phytopica^TM, a proprietary blend of standardised plant extracts, in canine atopic dermatitis (AD). One hundred twenty dogs with perennial AD were recruited on the basis of history and clinical signs, and a positive intradermal allergen test or rFcεRIα serology to perennial allergens. Other pruritic dermatoses were eliminated by antimicrobial treatment, skin scrapings, Sarcoptes serology, flea control and a 6‐week food trial. Exclusion criteria included antimicrobial therapy within 7 days, antihistamines within 14 days, oral/topical glucocorticoids or cyclosporin within 28 days, and parenteral glucocorticoids, essential fatty acids or immunotherapy within 56 days of entry into the study. Dogs [minimum Canine Atopic Dermatitis Extent and Severity Index (CADESI) = 25] were randomly allocated to receive placebo, 100, 200 or 400 mg/kg Phytopica^TM daily for 12 weeks. Their CADESI was assessed every 4 weeks. A modified intention‐to‐treat population was analysed. The mean reductions in CADESI scores at the end of treatment compared to baseline were 4.4% (100 mg/kg; n = 30), 23.4% (200 mg/kg; n = 29, P < 0.01), 8.5% (400 mg/kg; n = 29) and 3.9% (placebo; n = 29). For more severely affected dogs (minimum CADESI ≥ 50 at baseline), there was significant reduction in mean CADESI score (29.3%, P = 0.038) only in the 200 mg/kg treatment group (n = 14). In conclusion, this study demonstrates that Phytopica^TM is an effective nonsteroidal treatment for canine AD. Funding: Phytopharm plc.     

The effects of capsaicin topical therapy in dogs with atopic dermatitis: a randomized,double-blinded,placebo-controlled,cross-over clinical trial

Abstract The efficacy of twice daily topical application of capsaicin (0.025%) for the management of pruritus in dogs with atopic dermatitis (AD) was evaluated in double-blinded, placebo-controlled study. Twelve dogs with AD were randomly assigned to either 0.025% capsaicin or vehicle lotion applied twice daily for 6 weeks. After a 4-week wash-out period, treatments were switched. Significant improvement was reported by owners ( P  = 0.0006), but not by investigators. Owners noted temporary worsening of pruritus after the first week of capsaicin therapy. Overall capsaicin was well tolerated. Substance P (SP) concentrations in the skin did not correlate with the severity of the pruritus and did not change significantly over time and between treatments. Lesional skin had less SP than nonlesional skin ( P  = 0.03). These observations suggest that topical capsaicin should be further evaluated as an adjunctive antipruritic agent in dogs with AD.     

Clinical use of a ceramide-based moisturizer for treating dogs with atopic dermatitis

In humans, skin barrier dysfunction is thought to be responsible for enhanced penetration of allergens. Similar to conditions seen in humans, canine atopic dermatitis (CAD) is characterized by derangement of corneocytes and disorganization of intercellular lipids in the stratum corenum (SC) with decreased ceramide levels. This study was designed to evaluate the effects of a moisturizer containing ceramide on dogs with CAD. Dogs (n = 20, 3~8 years old) with mild to moderate clinical signs were recruited and applied a moisturizer containing ceramide for 4 weeks. Transepidermal water loss (TEWL), skin hydration, pruritus index for canine atopic dermatitis (PICAD) scores, and canine atopic dermatitis extent and severity index (CADESI) scores of all dogs were evaluated. Skin samples from five dogs were also examined with transmission electron microscopy (TEM) using ruthenium tetroxide. TEWL, PICAD, and CADESI values decreased (p < 0.05) and skin hydration increased dramatically over time (p < 0.05). Electron micrographs showed that the skin barrier of all five dogs was partially restored (p < 0.05). In conclusion, these results demonstrated that moisturizer containing ceramide was effective for treating skin barrier dysfunction and CAD symptoms.     

Evaluation of canine antimicrobial peptides in infected and noninfected chronic atopic skin

Background – Antimicrobial peptides (AMPs) are small immunomodulatory peptides produced by epithelial and immune cells. β‐Defensins (BDs) and cathelicidins (Caths) are the most studied AMPs. Recently, increased cutaneous expression of AMPs was reported in atopic humans and in beagles with experimentally induced atopy. Hypothesis/Objectives – Our goal was to analyse mRNA expression and protein levels of canine (c)BD1‐like, cBD2‐like/122, cBD3‐like, cBD103 and cCath in healthy and naturally affected atopic dogs, with and without active skin infection, along with their distribution in the epidermis using indirect immunofluorescence. Animals – Skin biopsies were taken from 14 healthy and 11 atopic privately owned dogs. Methods – The mRNA levels of cBD1‐like, cBD2‐like/122, cBD3‐like, cBD103 and cCath were quantified using quantitative real‐time PCR. The protein levels of cBD3‐like and cCath were analysed by relative competitive inhibition enzyme‐linked immunosorbent assay, while the distributions of cBD2‐like/122, cBD3‐like and cCath were detected by indirect immunofluorescence. Results – Dogs with atopic dermatitis had significantly greater mRNA expression of cBD103 (P = 0.04) than control dogs. Furthermore, atopic skin with active infection had a higher cBD103 mRNA expression (P = 0.01) and a lower cBD1‐like mRNA expression (P = 0.04) than atopic skin without infection. No significant differences in protein levels (cBD3‐like and cCath) or epidermal distribution of AMPs (cBD2‐like/122, cBD3‐like and cCath) were seen between healthy and atopic dogs. Conclusions and clinical importance – Expression of cBD103 mRNA was greater, while expression of cBD1‐like mRNA was lower in dogs with atopic dermatitis that had active infections. Work is needed to clarify the biological mechanisms and possible therapeutic options to maintain a healthy canine skin.     

Treatment of canine atopic dermatitis with cetirizine, a second generation antihistamine: A single-blinded, placebo-controlled study

Cetirizine and placebo were administered orally as individual agents to 23 dogs with atopic dermatitis. The pruritus was satisfactorily reduced in 4/22 (18%) dogs that completed the trial with cetirizine. Two dogs vomited after administration of the active drug.     

Evaluation of the bacterial microflora of the conjunctival sac of healthy dogs and dogs with atopic dermatitis

The aim of this case–control study was to evaluate and compare the bacterial microflora from the conjunctival sac of dogs with atopic dermatitis and healthy dogs. Twenty‐one atopic dogs without clinical and/or cytopathological signs of bacterial blepharoconjunctivitis and 21 breed‐matched healthy dogs were enrolled. Under topical anaesthesia, the inferior conjunctival sac of one eye was scraped twice. Material was collected with a Kimura spatula, spread over a slide and stained with a Diff Quick^®‐type stain (Medion Diagnostics GmbH, Düdingen, Switzerland) for cytological examination. An area of 0.5 cm² was examined at ×1000 magnification, and the types and numbers of cells and bacteria were recorded. A bacterial swab was collected and inoculated into culture media for the growth of aerobic bacteria. Before sampling, each atopic dog was evaluated for severity of cutaneous lesions, pruritus and conjunctival inflammation. Significant differences were observed between atopic and healthy dogs for the presence of bacteria on cytology (P = 0.015), keratinized (P = 0.001) and nonkeratinized epithelial cells (P = 0.013), eosinophils (P = 0.019) and lymphocytes (P = 0.008). Bacteria were recovered from 12 atopic dogs and three healthy dogs (P = 0.004). Staphylococcus pseudintermedius was the most commonly isolated species in atopic dogs (seven of 12). In atopic dogs, no significant relation was found between conjunctival bacterial colonization (on cytology and culture) and the severity of any of the clinical parameters. This study suggests differences in conjunctival bacterial colonization and cytological features between atopic and healthy dogs.     

Aspects of the humoral immune response to Staphylococcus intermedius in dogs with superficial pyoderma,deep pyoderma and anal furunculosis

Bacterial infection (pyoderma) of the canine skin is largely caused by Staphylococcus intermedius and may be a superficial or deep infection. Pyoderma may be a primary, idiopathic disease or secondary to a range of other dermatological disorders. In this study, the serum concentrations of IgG, IgA, antistaphylococcal IgG and antistaphylococcal IgA were measured by ELISA in normal dogs (n = 22), dogs with idiopathic deep pyoderma (n = 22), atopic dermatitis and superficial pyoderma (n = 24), atopic dermatitis without pyoderma (n = 25), flea bite dermatitis with superficial pyoderma (n = 8), pustular demodicosis (n = 8) and German shepherd dogs with anal furunculosis (n = 28). The serum IgG was significantly increased in dogs with atopy and superficial pyoderma (p < 0.001), and lower than normal in dogs with idiopathic deep pyoderma (p < 0.015). The concentration of serum IgA was significantly lower than normal in dogs with atopy uncomplicated by pyoderma (p < 0.015). The concentration of antistaphylococcal IgG in all clinical sera was significantly elevated (p < 0.001) when compared to normal dogs but concentrations of antistaphylococcal IgA were no greater than in normal dogs. Western blotting analysis for determination of the specificity of serum IgG antistaphylococcal antibody revealed that there were nine major epitopes. Discriminant analysis demonstrated that particular combinations of these epitopes were recognised more frequently by sera from dogs in different clinical groups.     

Treatment of canine atopic dermatitis with a commercial homeopathic remedy: a single-blinded,placebo-controlled study

A commercial homeopathic remedy and a placebo were administered orally as individual agents to 18 dogs with atopic dermatitis. The pruritus was reduced by less than 50% in only 2/18 dogs; 1 of these dogs was receiving the homeopathic remedy, the other was receiving the placebo. One dog vomited after administration of the homeopathic remedy.     

Treatment of canine atopic dermatitis with zafirlukast, a leukotriene-receptor antagonist: a single-blinded, placebo-controlled study

Zafirlukast and placebo were administered orally as individual agents to 20 dogs with atopic dermatitis. The pruritus was effectively reduced by at least 50% in 2/18 (11%) dogs that completed the trial with zafirlukast. Two dogs vomited after administration of the active drug.     

Mast cell distribution,epidermal thickness and hair follicle density in normal canine skin: possible explanations for the predilection sites of atopic dermatitis?

Mast cell counts, epidermal thickness and hair follicle density were quantified in toluidine blue stained sections of normal skin from 20 different body regions in 10 dogs and compared to the predilection sites of canine atopic dermatitis. Mast cell distribution varied significantly from site to site (P < 0.0001) and counts in the superficial dermis were significantly higher than the deeper dermis (P < 0.05). Mast cell counts were highest in the medial and lateral pinna (mean 10.4–11.3 per high power field, HPF) and in the ventral interdigital skin of the hind and fore feet (mean 9.2–9.5 per HPF). Counts in these regions were at least 150% higher than all the other sites (means ranging between 2.9 and 6.0 per HPF). Variations in mast cell counts, epidermal thickness or hair follicle density did not adequately explain the predilection sites of canine atopic dermatitis. However, the results provide some evidence that cutaneous mast cell distribution may be involved in the frequent occurrence of ear and foot pruritus in this disease.