Longitudinal Evaluation of the Skin Microbiome and Association with Microenvironment and Treatment in Canine Atopic Dermatitis

Clinical and Genetic Findings in 28 American Cocker Spaniels with Aural Ceruminous Gland Hyperplasia and Ectasia

American Cocker Spaniels (ACSs) develop aural ceruminous gland hyperplasia and ectasia more often than dogs of other breeds. Data on the cause and development of these breed characteristic histopathological changes are lacking. We performed video-otoscopic examinations and dermatological work-up on 28 ACSs, obtained aural biopsies from each dog and assessed the statistical associations between the presence of ceruminous gland hyperplasia and ectasia and disease history, clinical or microbiological findings and underlying cause of otitis externa (OE). Histological lesions of ceruminous gland hyperplasia and ectasia were observed in aural biopsies from 6/13 clinically healthy ears and 13/15 ears with OE from 19/28 examined dogs. Nine of 28 dogs had histologically normal ceruminous glands (odds ratio [OR] 6.2, 95% confidence interval [CI] 1.1-36.6). Bacterial growth in microbiological culture of aural exudate (OR 14.1, 95% CI 2.1-95.3) was associated with ceruminous glandular changes, whereas previous history of OE, cutaneous findings or underlying allergies were not. Pedigree analysis and a genome-wide association study (GWAS) were performed on 18 affected and eight unaffected dogs based on histopathological diagnosis. While the GWAS indicated a tentative, but not statistically significant, association of ceruminous gland hyperplasia and ectasia with chromosome 31, a larger cohort is needed to confirm this preliminary result. Based on our results, ceruminous gland hyperplasia and ectasia may also precede clinical signs of OE in ACSs and a genetic aetiological component is likely Further studies with larger cohorts are warranted to verify our preliminary results.

Preliminary evaluation of two bathing methods for the management of Malassezia overgrowth in dogs with atopic dermatitis

BACKGROUND

Antifungal shampoos are widely used for canine Malassezia dermatitis. Few studies have evaluated effective bathing methods for atopic dogs with Malassezia overgrowth.

OBJECTIVES

To evaluate the efficacy of an emollient bathing product (AFLOAT VET) and 2% miconazole/2% chlorhexidine shampoo (2% MIC/CHX) in atopic dogs, and to evaluate the influence on skin barrier function of both products in healthy dogs.

ANIMALS

Sixteen atopic dogs with secondary Malassezia overgrowth and 11 healthy dogs.

METHODS AND MATERIALS

This study was a randomized, single-blinded trial. The dogs were randomly treated with either emollient bathing or 2% MIC/CHX, twice weekly for four weeks. Clinical assessment used the Canine Atopic Dermatitis Extent and Severity Index, 4^th iteration (CADESI-04), pruritus Visual Analog Scale (pVAS), and cytological evaluation of yeast numbers at Day (D)0, D14 and D28. Skin barrier function was determined by measuring transepidermal water loss (TEWL) after a single bathing procedure with each product in the healthy dogs.

RESULTS

The pVAS scores and yeast counts were significantly reduced on D28 compared with D0 in both groups (P < 0.05). CADESI-04 was significantly decreased on D28 in the emollient bathing group (P = 0.003). There were no significant differences in each endpoint score between the groups. In healthy dogs, TEWL was significantly increased after bathing in both groups (P < 0.01).

CONCLUSION

An emollient bathing product can be effective for Malassezia overgrowth in dogs with atopic dermatitis. Bathing with shampoo products might affect skin barrier function even when using an emollient product.

Exogenous factors in the pathogenesis of atopic dermatitis: Irritants and cutaneous infections

Atopic dermatitis (AD) is a chronic relapsing inflammatory cutaneous disease that is often associated with other atopic symptoms, such as food allergy, allergic rhinitis and asthma, leading to significant morbidity and healthcare costs. The pathogenesis of AD is complicated and multifactorial. Although the aetiology of AD remains incompletely understood, recent studies have provided further insight into AD pathophysiology, demonstrating that the interaction among genetic predisposition, immune dysfunction and environmental provocation factors contributes to its development. However, the increasing prevalence of AD suggests that environmental factors such as irritation and cutaneous infection play a crucial role in triggering and/or aggravating the disease. Of note, AD skin is susceptible to bacterial, fungal and viral infections, and microorganisms may colonize the skin and aggravate AD symptoms. Overall, understanding the mechanisms by which these risk factors affect the cutaneous immunity of patients with AD is of great importance for developing a precision medicine approach for treatment. This review summarizes recent developments in exogenous factors involved in the pathogenesis of AD, with special emphasis on irritants and microbial infections.

Mesenchymal Stem cells in the context of canine atopic dermatitis: A Review

ABSTRACT Canine atopic dermatitis (CAD) is a chronic inflammatory skin disease and has a high frequency among dermatological diseases. The interaction of genetic factors, skin and environmental conditions affect the expression of the disease, developing a complex pathology. Current multimodal treatment has numerous adverse effects and variations in its efficacy and safety, demonstrating the need to develop safe and effective therapeutic resources for patients with CAD. Mesenchymal stem cells (MSCs) are multipotent cells, with special characteristics, such as self-renewal, immunomodulatory properties, and de-differentiation, making them useful for several clinical problems. The discovery of the immunosuppressive effect of MSCs on T cells has opened the potential for new perspectives with its use as a therapeutic agent for immune diseases, such as CAD. The scarce number of research using the MSC as a treatment for CAD result in the lack of knowledge about the benefits and possible protocols to be followed for the use of this cell therapy. In this review, we highlighted the clinical studies and potential biological mechanisms of MSC-based cell therapy effects attenuating canine atopic dermatitis compared to conventional treatment, which might lead to a safe improvement of the animal’s clinical condition in a short period without causing adverse effects.

Simultaneous allergic traits in dogs and their owners are associated with living environment, lifestyle and microbial exposures

Both humans and pet dogs are more prone to develop allergies in urban than in rural environments, which has been associated with the differing microbial exposures between areas. However, potential similarities in the microbiota, that associate with environmental exposures, in allergic dogs and owners has not been investigated. We evaluated skin and gut microbiota, living environment, and lifestyle in 168 dog-owner pairs. Due to partly different manifestations of allergies between species, we focused on aeroallergen sensitized humans and dogs with owner-reported allergic symptoms. Our results agree with previous studies: dog-owner pairs suffered simultaneously from these allergic traits, higher risk associated with an urban environment, and the skin, but not gut, microbiota was partly shared by dog-owner pairs. We further discovered that urban environment homogenized both dog and human skin microbiota. Notably, certain bacterial taxa, which were associated with living environment and lifestyle, were also related with allergic traits, but these taxa differed between dogs and humans. Thus, we conclude that dogs and humans can be predisposed to allergy in response to same risk factors. However, as shared predisposing or protective bacterial taxa were not discovered, other factors than environmental microbial exposures can mediate the effect or furry dog and furless human skin select different taxa.

A shotgun metagenomic investigation of the microbiota of udder cleft dermatitis in comparison to healthy skin in dairy cows

Udder cleft dermatitis (UCD) is a skin condition affecting the fore udder attachment of dairy cows. UCD may be defined as mild (eczematous skin changes) or severe (open wounds, large skin changes). Our aims were to compare the microbiota of mild and severe UCD lesions with the microbiota of healthy skin from the fore udder attachment of control cows, and to investigate whether mastitis-causing pathogens are present in UCD lesions. Samples were obtained from cows in six dairy herds. In total, 36 UCD samples categorized as mild (n = 17) or severe (n = 19) and 13 control samples were sequenced using a shotgun metagenomic approach and the reads were taxonomically classified based on their k-mer content. The Wilcoxon rank sum test was used to compare the abundance of different taxa between different sample types, as well as to compare the bacterial diversity between samples. A high proportion of bacteria was seen in all samples. Control samples had a higher proportion of archaeal reads, whereas most samples had low proportions of fungi, protozoa and viruses. The bacterial microbiota differed between controls and mild and severe UCD samples in both composition and diversity. Subgroups of UCD samples were visible, characterized by increased proportion of one or a few bacterial genera or species, e.g. Corynebacterium, Staphylococcus, Brevibacterium luteolum, Trueperella pyogenes and Fusobacterium necrophorum. Bifidobacterium spp. were more common in controls compared to UCD samples. The bacterial diversity was higher in controls compared to UCD samples. Bacteria commonly associated with mastitis were uncommon. In conclusion, a dysbiosis of the microbiota of mild and severe UCD samples was seen, characterized by decreased diversity and an increased proportion of certain bacteria. There was no evidence of a specific pathogen causing UCD or that UCD lesions are important reservoirs for mastitis-causing bacteria.

Cerumen microbial community shifts between healthy and otitis affected dogs

Otitis externa is a common multifactorial disease in dogs, characterized by broad and complex modifications of the ear microbiota. The goal of our study was to describe the ear cerumen microbiota of healthy dogs, within the same animal and between different animals, and to compare the cerumen microbiota of otitis affected dogs with that of healthy animals. The present study included 26 healthy dogs, 16 animals affected by bilateral otitis externa and 4 animals affected by monolateral otitis externa. For each animal cerumen samples from the right and left ear were separately collected with sterile swabs, and processed for DNA extraction and PCR amplification of the 16S rRNA gene. Amplicon libraries were sequenced using an Ion Torrent Personal Genome Machine (PGM), and taxonomical assignment and clustering were performed using QIIME 2 software. Our results indicate that the bacterial community of the cerumen in healthy dogs was characterized by extensive variability, with the most abundant phyla represented by Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Fusobacteria. The analysis of both alpha and beta diversity between pairs of left and right ear samples from the same dog within the group of affected animals displayed higher differences than between paired samples across healthy dogs. Moreover we observed reduced bacterial richness in the affected group as compared with controls and increased variability in population structure within otitis affected animals, often associated with the proliferation of a single bacterial taxon over the others. Moreover, Staphylococcus and Pseudomonas resulted to be the bacterial genera responsible for most distances between the two groups, in association with differences in the bacterial community structure. The cerumen microbiota in healthy dogs exhibits a complex bacterial population which undergoes significant modifications in otitis affected animals.

Changes in the ear canal microbiota of dogs with otitis externa

AIMS

Otitis externa (OE), one of the most common ear diseases in dogs, is caused by bacterial pathogens such as Staphylococcus sp. To understand the network of microbial communities in the canine ear canal affected with OE, we performed a cross-sectional study using next-generation sequencing.

METHODS AND RESULTS

Ear swab samples were collected from 23 OE-affected and 10 healthy control dogs, and the 16S rRNA gene sequenced using Illumina MiSeq. The otic microbiota in the OE-affected dogs showed significantly decreased alpha diversity compared to controls. The community composition also differed in the affected group, with significantly higher relative abundance of the phylum Firmicutes and the genus Staphylococcus (P = 0·01 and 0·04 respectively). Contrary to our expectations, the severity of the disease did not impact the otic microbiota in OE-affected dogs.

CONCLUSIONS

The ear canal microbiota of OE-affected dogs is distinct from that of healthy dogs, irrespective of disease status.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study, one of the few detailed analyses of the otic microbiota, can provide practical information for the appropriate treatment of canine OE.

Characterization of staphylococcal communities on healthy and allergic feline skin

BACKGROUND

Various Staphylococcus species have been demonstrated to play important roles on the skin, including causing disease and protecting the host from pathogens. Although culture-based studies have isolated various Staphylococcus spp. from feline skin, very little is known regarding the species-level communities on the host.

HYPOTHESIS/OBJECTIVES

To describe the species-level staphylococcal communities inhabiting the skin of healthy cats and cats with allergic dermatitis.

ANIMALS

Skin swabs from the ear canal and groin of 11 healthy and 10 allergic (nonlesional) cats were obtained.

METHODS AND MATERIALS

DNA was extracted from the skin swabs and used for next-generation sequencing targeting the V1-3 region of the 16S rRNA gene. Following a standard microbiota analysis of the sequencing data, species-level assignment for the staphylococcal sequences were obtained using a staphylococci-specific database.

RESULTS

Staphylococcus spp. had similar relative abundance in healthy and allergic samples. The most abundant staphylococcal species were S. epidermidis in healthy samples, and S. felis and S. capitis in allergic samples. The composition of staphylococcal communities, as well as relative abundance of Staphylococcus spp., was variable between body sites and individual cats sampled.

CONCLUSIONS AND CLINICAL RELEVANCE

These results demonstrate that diverse staphylococcal communities inhabit the skin of healthy and allergic cats, and provide a starting point for further research into the importance of Staphylococcus spp. in feline allergic skin disease.

Management of canine perianal fistula with fluorescence light energy: preliminary findings

BACKGROUND

Canine perianal fistula (CPF) is a severe, painful, debilitating skin condition affecting the perianal skin. It often interferes with the quality of life of both dog and owner. Conventional medical treatment involves the use of immunosuppressive therapy; however, the successful resolution of lesions can be limited by poor owner compliance, adverse drug effects and dependence on costly therapies.

HYPOTHESIS/OBJECTIVES

The present study aimed to assess the potential benefits of fluorescent light energy (FLE) on cases of CPF.

ANIMALS

Four dogs with active perianal fistulas METHODS AND MATERIALS: FLE was applied as sole management therapy once a week with two consecutive applications in the same session for each dog until clinical signs had significantly improved, with weekly assessments for a six week period. Dogs were assessed by measuring the size of lesions at the start of the study and then weekly for six weeks, using planimetry software. Owners recorded vocalization and straining frequency scores during their pet's defaecation, and perianal licking frequency on a 0-5 point scale to assess the response to therapy.

RESULTS

All dogs improved with FLE, achieving a significant reduction in vocalization, straining and licking after two weeks (P = 0.002). After five weeks of FLE therapy, lesional areas had significantly decreased (P = 0.04). Only one dog required more than seven applications. No adverse events were reported.

CONCLUSION AND CLINICAL IMPORTANCE

FLE may be a promising alternative therapy for CPF.

Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

The genus Malassezia is comprised of a group of lipophilic yeasts that have evolved as skin commensals and opportunistic cutaneous pathogens of a variety of mammals and birds.

OBJECTIVES

The objective of this document is to provide the veterinary community and other interested parties with current information on the ecology, pathophysiology, diagnosis, treatment and prevention of skin diseases associated with Malassezia yeasts in dogs and cats.

METHODS AND MATERIAL

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to October 2018. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) Clinical Consensus Guideline committee provided guidance and oversight for this process. The document was presented at two international meetings of veterinary dermatology societies and one international mycology workshop; it was made available for comment on the WAVD website for a period of six months. Comments were shared with the GP electronically and responses incorporated into the final document.

CONCLUSIONS AND CLINICAL IMPORTANCE

There has been a remarkable expansion of knowledge on Malassezia yeasts and their role in animal disease, particularly since the early 1990's. Malassezia dermatitis in dogs and cats has evolved from a disease of obscurity and controversy on its existence, to now being a routine diagnosis in general veterinary practice. Clinical signs are well recognised and diagnostic approaches are well developed. A range of topical and systemic therapies is known to be effective, especially when predisposing factors are identified and corrected.

Characterization of Cutaneous Bacterial Microbiota from Superficial Pyoderma Forms in Atopic Dogs

Although Staphylococcus pseudintermedius is considered the major pathogen associated with superficial canine pyoderma, no study has investigated the entire bacterial community in these lesions with molecular techniques. The objectives of this study were to characterize the bacterial microbiota in two forms of superficial canine pyoderma lesions, superficial bacterial folliculitis (SBF) and epidermal collarette (EC), especially in terms of the staphylococcal community. Swabs from 12 SBF and 9 EC lesions were obtained from eight and six atopic dogs, respectively. Eight samples from the axilla and groin of four healthy dogs served as controls. DNA was extracted for 16S rRNA gene sequencing and quantitative polymerase chain reaction of Staphylococcus spp. and S. pseudintermedius. Healthy skin samples harbored significantly more diverse bacterial communities than pyoderma samples. Healthy samples had communities that were more similar to each other, and were distinct from pyoderma samples. Staphylococcus spp. abundance was increased in pyoderma samples, especially those from EC samples. Although determining species-level identities of staphylococcal sequences revealed many species, S. pseudintermedius was the primary staphylococcal species found in all sample types. As expected, there are many differences in the microbiota when comparing healthy and canine pyoderma lesions samples. These lesions do not seem to be associated with a change in the relative abundance of specific Staphylococcus species, but simply an overall increase in Staphylococcus spp. abundance. The results of this study provide a starting point for future studies investigating how antimicrobial treatments may further change the microbiota associated with these lesions.

Characterization of skin surface and dermal microbiota in dogs with mast cell tumor

The skin microbiota interacts with the host immune response to maintain the homeostasis. Changes in the skin microbiota are linked to the onset and the progression of several diseases, including tumors. We characterized the skin surface and dermal microbiota of 11 dogs affected by spontaneous mast cell tumor (MCT), using skin contralateral sites as intra-animal healthy controls. The microbial profile differed between healthy and tumor skin surfaces and dermis, demonstrating that the change in microbiota composition is related to the presence of MCT. The number of observed taxa between MCT and healthy skin surfaces was detected, showing a decrease in number and heterogeneity of taxa over the skin surface of MCT, at both inter- and intra-individual level. Preliminary data on bacterial population of MCT dermis, obtained only on three dogs, demonstrated an intra-individual reduction of taxa number when compared to the skin surface. Taxonomy reveals an increase of Firmicutes phylum and Corynebacteriaceae family in MCT skin surface when compared to the healthy contralateral. In conclusion, we demonstrate that microbial population of skin surface and dermis is related to mast cell tumor. Our study provides the basis for future investigations aiming to better define the interaction between mast cell tumors, microbiota and host immune response.

Update on pathogenesis, diagnosis, and treatment of atopic dermatitis in dogs

Improved understanding of the pathogenesis of atopic dermatitis in dogs has led to more effective treatment plans, including skin barrier repair and new targeted treatments for management of allergy-associated itch and inflammation. The intent of this review article is to provide an update on the etiologic rationale behind current recommendations that emphasize a multimodal approach for the management of atopic dermatitis in dogs. Increasing knowledge of this complex disease process will help direct future treatment options.

The canine skin and ear microbiome: A comprehensive survey of pathogens implicated in canine skin and ear infections using a novel next-generation-sequencing-based assay

This study analyzed the complex bacterial and fungal microbiota of healthy and clinically affected canine ear and skin samples. A total of 589 canine samples were included: 257 ear swab samples (128 healthy vs. 129 clinically affected) and 332 skin swab samples (172 healthy vs. 160 clinically affected) were analyzed using next-generation sequencing (NGS) to determine both relative and absolute abundances of bacteria and fungi present in the samples. This study highlighted the canine microbiota of clinically affected cases was characterized by an overall loss of microbial diversity, high microbial biomass, with overgrowth of certain members of the microbiota. The observed phenotype of these samples was best described by the combination of both relative and absolute microbial abundances. Compared to healthy samples, 78.3% of the clinically affected ear samples had microbial overgrowth; 69.8% bacterial overgrowth, 16.3% fungal overgrowth, and 7.0% had both bacterial and fungal overgrowth. The most important microbial taxa enriched in clinically affected ears were Malassezia pachydermatis, Staphylococcus pseudintermedius, Staphylococcus schleiferi, and a few anaerobic bacteria such as Finegoldia magna, Peptostreptococcus canis, and Porphyromonas cangingivalis. The anaerobic microbes identified here were previously not commonly recognized as pathogens in canine ear infections. Similar observations were found for skin samples, but yeasts and anaerobes were less abundant when compared to clinically affected cases. Results highlighted herein, signify the potential of NGS-based methods for the accurate quantification and identification of bacterial and fungal populations in diagnosing canine skin and ear infections, and highlight the limitations of traditional culture-based testing.

Impact of the early-life skin microbiota on the development of canine atopic dermatitis in a high-risk breed birth cohort

Canine atopic dermatitis (CAD) is a prevalent inflammatory skin disease of dogs worldwide. Certain breeds such as the West Highland White Terriers (WHWT) are predisposed to suffer from CAD. Microbial dysbiosis is known to play a significant role in the pathogenesis of the disease, which is similar to its human counterpart, atopic dermatitis (AD). To date, no large cohort-study has been conducted in a predisposed dog breed to study the impact of the early-life microbiota on the development of CAD, as well as the possible implication of factors such as hygiene and access to the outdoors. In this study skin samples of 143 WHWT, including 109 puppies up to three weeks old and 34 parent dogs, from 17 breeders, were subjected to 16S rRNA gene and ITS2 amplicon sequencing to disclose the bacterial and fungal oral and skin microbiota, respectively. The oral samples served as a control group to confirm differences between haired and mucosal surfaces. The cutaneous microbiota differed between sample sites and age of the dogs. The season of sampling, geographical origin as well as hygiene status of the household and the access to the outdoors shaped the skin microbiota of the puppies significantly. However, we found that the individual early-life microbiota did not predispose for the later development of CAD.

The otic microbiota and mycobiota in a referral population of dogs in eastern USA with otitis externa

BACKGROUND

Canine otitis externa (OE) is a common inflammatory disease that is frequently complicated by secondary bacterial and/or yeast infections. The otic microbial population is more complex than appreciated by cytological methods and aerobic culture alone.

HYPOTHESIS/OBJECTIVES

Differences in bacterial and fungal populations of the external ear canal will correlate with specific cytological and culture-based definitions of bacterial and Malassezia otitis.

ANIMALS

Forty client-owned dogs; 30 with OE and 10 with healthy ears.

METHODS AND MATERIALS

Prospective study comparing cytological samples, aerobic bacterial cultures and culture-independent sequencing-based analyses of the external ear canal. Subjects with OE included 10 dogs with only cocci [≥25/high power field (HPF)] on cytological evaluation and culture of Staphylococcus spp.; 10 dogs with rods (≥25/HPF) and exclusive culture of Pseudomonas aeruginosa; 10 dogs with only yeast on cytological results morphologically compatible with Malassezia spp. (≥5/HPF).

RESULTS

Staphylococcus was the most abundant taxa across all groups. Ears cytologically positive for cocci had decreased diversity, and all types of OE were associated with decreased fungal diversity compared to controls.

CONCLUSIONS AND CLINICAL IMPORTANCE

Cytological and culture-based assessment of the ear canal is not predictive of the diverse microbiota of the ear canal in cases of Pseudomonas or Malassezia otitis. Less abundant bacterial taxa in cases of staphylococcal OE are worth scrutiny for future biological therapy.

Characterization and Analysis of the Skin Microbiota in Rosacea: Impact of Systemic Antibiotics

Systemic antibiotics are extensively used to control the papules and pustules of rosacea. Hence, it is crucial to understand their impact on the rosacea skin microbiota which is thought to be perturbed. The purpose of this study was to compare the makeup and diversity of the skin microbiota in rosacea before and after taking oral antibiotics. We also compared the skin microbiota at baseline according to age and rosacea severity. A longitudinal cohort study was performed on 12 rosacea patients with papules/pustules and no recent use of oral and topical antimicrobials/retinoids. Patients were prescribed oral doxycycline, 100 mg, twice daily for six weeks. Skin areas on the cheek and nose were sampled for 16S ribosomal RNA gene sequencing at baseline, and after six weeks of doxycycline treatment. Eleven females and one male aged 20–79 (median 51) with a median Investigator’s Global Assessment score of 3 (moderate) were enrolled. At baseline, Staphylococcus epidermidis was the most dominant species followed by Cutibacterium acnes (formerly Propionibacterium acnes). In the 60 Over-age group, the prevalence of Cutibacterium acnes was lower than that of the 60 & Under-age group. Rosacea severity increased with age and was associated with a decrease in the relative abundance of Cutibacterium acnes and an increase of Snodgrassella alvi. Across all subjects, antibiotic treatment reduced clinical rosacea grades and was associated with an increase in the relative abundance of Weissella confusa (P = 0.008, 95% CI 0.13% to 0.61%). Bacterial diversity (alpha diversity) was not significantly altered by antibiotics treatment. Principal coordinates analysis showed mild clustering of samples by patient (ANOSIM, Analysis of Similarity, R = 0.119, P = 0.16) and scant clustering with treatment (ANOSIM, R = 0.002; P = 0.5). In conclusion, we believe that rosacea has a unique age-dependent characteristic (i.e., severity). Although we were not able to pinpoint a causative microbiota, our study provides a glimpse into the skin microbiota in rosacea and its modulation by systemic antibiotics.

Ear mite infection is associated with altered microbial communities in genetically depauperate Santa Catalina Island foxes (Urocyon littoralis catalinae)

The host-associated microbiome is increasingly recognized as a critical player in health and immunity. Recent studies have shown that disruption of commensal microbial communities can contribute to disease pathogenesis and severity. Santa Catalina Island foxes (Urocyon littoralis catalinae) present a compelling system in which to examine microbial dynamics in wildlife due to their depauperate genomic structure and extremely high prevalence of ceruminous gland tumors. Although the precise cause is yet unknown, infection with ear mites (Otodectes cynotis) has been linked to chronic inflammation, which is associated with abnormal cell growth and tumor development. Given the paucity of genomic variation in these foxes, other dimensions of molecular diversity, such as commensal microbes, may be critical to host response and disease pathology. We characterized the host-associated microbiome across six body sites of Santa Catalina Island foxes, and performed differential abundance testing between healthy and mite-infected ear canals. We found that mite infection was significantly associated with reduced microbial diversity and evenness, with the opportunistic pathogen Staphylococcus pseudintermedius dominating the ear canal community. These results suggest that secondary bacterial infection may contribute to the sustained inflammation associated with tumor development. As the emergence of antibiotic resistant strains remains a concern of the medical, veterinary, and conservation communities, uncovering high relative abundance of S. pseudintermedius provides critical insight into the pathogenesis of this complex system. Through use of culture-independent sequencing techniques, this study contributes to the broader effort of applying a more inclusive understanding of molecular diversity to questions within wildlife disease ecology.

Commensal Staphylococci Including Methicillin-Resistant Staphylococcus aureus from Dogs and Cats in Remote New South Wales, Australia

Staphylococci are important opportunistic pathogens in human and veterinary medicine in addition to being part of the normal flora of the skin and mucous membranes of mammals and birds. The rise of antimicrobial resistance amongst staphylococci warrants closer investigation of the diversity of skin commensal organisms-including coagulase-negative staphylococci (CoNS)-due to their potential as a source of resistance genes. This study is aimed at characterising the commensal staphylococci-including methicillin-resistant Staphylococcus species (spp.)-from mucocutaneous sites of dogs and cats from remote New South Wales (NSW), Australia. Pet dogs and cats were recruited from participants in a community companion animal health programme in six communities in western NSW. Three swabs were collected from each animal (anterior nares, oropharynx, and perineum) and from skin lesions or wounds if present and cultured on selective media for Staphylococcus spp. In total, 383 pets (303 dogs, 80 cats) were enrolled. Staphylococcus spp. were isolated from 67.3% of dogs and 73.8% of cats (494 isolates). The diversity of CoNS was high (20 species) whilst only three coagulase-positive spp. were isolated (S. pseudintermedius, S. aureus, S. intermedius). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage in dogs was high (2.6%) relative to other studies but was only a small proportion of overall commensal staphylococci. No cats carried MRSA and no MRSP was isolated from either species. Dogs were significantly more likely to carry coagulase-positive staphylococci than cats (P < 0.001). Amongst dogs, males and those with skin lesions were more likely to carry S. pseudintermedius. This study highlights important differences in the diversity and patterns of carriage of commensal staphylococci between dogs and cats in remote NSW, Australia.

Multidose intramuscular allogeneic adipose stem cells decrease the severity of canine atopic dermatitis: A pilot study

Aim

The aim of this pilot study was to evaluate the therapeutic and safety performance of an intramuscular treatment protocol of multidose of allogeneic adipose stem cells (ASCs) isolated, characterized, and expanded ex vivo from a healthy canine donor.

Materials and Methods

Twelve dogs diagnosed with canine atopic dermatitis (CAD) were intramuscularly treated with 0.5×10⁶ of cryopreserved ASCs from a healthy immunized young canine Ehrlichia canis free donor weekly for 6 weeks. Treatment efficacy was evaluated by the pruritus index and the CAD Lesion Index (CADLI) test. Safety and adverse effects were determined by injection site reaction, weight, blood chemistry, liver function, and whole blood count.

Results

Canine ASCs obtained from a donor met the minimum qualities required for this type of cells and showed viability of 90% after thawing. The efficacy of the CADLI score and the pruritus index in 12 dogs with atopic dermatitis was statistically significant efficacy. No adverse reactions were observed at the intramuscular application site, or in relation to animal weight, blood cell populations, or liver and renal function.

Conclusion

These results suggest that intramuscular administration of cryopreserved ASCs to dogs with atopic dermatitis is a promising cellular therapeutic product for the relief of the symptoms of this disease; however, the duration of the effects obtained with this dose and with other doses should be evaluated, as well as possible immune reactions. As far as we know, this is the first report of the use of multiple intramuscular doses cryopreserved ASCs to treat atopic dermatitis.

Of microbes and mange: consistent changes in the skin microbiome of three canid species infected with Sarcoptes scabiei mites

Background

Sarcoptic mange is a highly contagious skin disease caused by the ectoparasitic mite Sarcoptes scabiei. Although it afflicts over 100 mammal species worldwide, sarcoptic mange remains a disease obscured by variability at the individual, population and species levels. Amid this variability, it is critical to identify consistent drivers of morbidity, particularly at the skin barrier.

Methods

Using culture-independent next generation sequencing, we characterized the skin microbiome of three species of North American canids: coyotes (Canis latrans), red foxes (Vulpes vulpes) and gray foxes (Urocyon cinereoargenteus). We compared alpha and beta diversity between mange-infected and uninfected canids using the Kruskal–Wallis test and multivariate analysis of variance with permutation. We used analysis of composition of microbes and gneiss balances to perform differential abundance testing between infection groups.

Results

We found remarkably consistent signatures of microbial dysbiosis associated with mange infection. Across genera, mange-infected canids exhibited reduced microbial diversity, altered community composition and increased abundance of opportunistic pathogens. The primary bacteria comprising secondary infections were Staphylococcus pseudintermedius, previously associated with canid ear and skin infections, and Corynebacterium spp., previously found among the gut flora of S. scabiei mites and hematophagous arthropods.

Conclusions

This evidence suggests that sarcoptic mange infection consistently alters the canid skin microbiome and facilitates secondary bacterial infection, as seen in humans and other mammals infected with S. scabiei mites. These results provide valuable insights into the pathogenesis of mange at the skin barrier of North American canids and can inspire novel treatment strategies. By adopting a “One Health” framework that considers mites, microbes and the potential for interspecies transmission, we can better elucidate the patterns and processes underlying this ubiquitous and enigmatic disease.

Bacteriophage of the Skin Microbiome in Patients with Psoriasis and Healthy Family Controls

The bacteriophage (phage) component of the skin microbiome in patients with psoriasis has not been systematically explored. The purpose of this study is to investigate phage and bacterial components of the skin microbiome in patients with psoriasis and in healthy family controls. Lesional skin swabs of four different locations (elbow, forearm, knee, and scalp) were taken from patients with psoriasis. Healthy skin swabs of matched locations were taken from contralateral non-lesional skin and healthy family controls. Skin microbiomes were investigated using next-generation shotgun metagenomics sequencing. 81 skin microbiome samples (27 lesional skin samples and 54 healthy skin samples from contralateral non-lesional skin and family controls) obtained from 16 subjects with psoriasis and 16 matched family controls were sequenced and analyzed. Among phage species with abundant host bacteria, two significantly differential abundant phage species, Acinetobacter phage Presley and Pseudomonas phage O4 (adjusted P < 0.05), between psoriasis lesional skin and healthy skin were identified. Samples with high levels of these phage species had their host bacteria abundance suppressed (P = 0.03 and P < 0.001). Differential phage composition between lesional skin in patients with psoriasis and healthy skin from contralateral non-lesional sites and family controls, as well as the suppression of bacteria host of the respective phage, suggest possible avenues for probiotic phage therapeutics.

The skin microbiome of vertebrates

The skin constitutes the primary physical barrier between vertebrates and their external environment. Characterization of skin microorganisms is essential for understanding how a host evolves in association with its microbial symbionts, modeling immune system development, diagnosing illnesses, and exploring the origins of potential zoonoses that affect humans. Although many studies have characterized the human microbiome with culture-independent techniques, far less is known about the skin microbiome of other mammals, amphibians, birds, fish, and reptiles. The aim of this review is to summarize studies that have leveraged high-throughput sequencing to better understand the skin microorganisms that associate with members of classes within the subphylum Vertebrata. Specifically, links will be explored between the skin microbiome and vertebrate characteristics, including geographic location, biological sex, animal interactions, diet, captivity, maternal transfer, and disease. Recent literature on parallel patterns between host evolutionary history and their skin microbial communities, or phylosymbiosis, will also be analyzed. These factors must be considered when designing future microbiome studies to ensure that the conclusions drawn from basic research translate into useful applications, such as probiotics and successful conservation strategies for endangered and threatened animals.

Microbiome of the Skin and Gut in Atopic Dermatitis (AD): Understanding the Pathophysiology and Finding Novel Management Strategies

Atopic dermatitis (AD) is a long-standing inflammatory skin disease that is highly prevalent worldwide. Multiple factors contribute to AD, with genetics as well as the environment affecting disease development. Although AD shows signs of skin barrier defect and immunological deviation, the mechanism underlying AD is not well understood, and AD treatment is often very difficult. There is substantial data that AD patients have a disturbed microbial composition and lack microbial diversity in their skin and gut compared to controls, which contributes to disease onset and atopic march. It is not clear whether microbial change in AD is an outcome of barrier defect or the cause of barrier dysfunction and inflammation. However, a cross-talk between commensals and the immune system is now noticed, and their alteration is believed to affect the maturation of innate and adaptive immunity during early life. The novel concept of modifying skin and gut microbiome by applying moisturizers that contain nonpathogenic biomass or probiotic supplementation during early years may be a preventive and therapeutic option in high risk groups, but currently lacks evidence. This review discusses the nature of the skin and gut flora in AD, possible mechanisms of skin-gut interaction, and the therapeutic implications of microbiome correction in AD.

Pilot study using five methods to evaluate skin barrier function in healthy dogs and in dogs with atopic dermatitis

BACKGROUND

Atopic dermatitis is associated with skin barrier defects. In people, noninvasive techniques are used to quantify the skin barrier functionality. In dogs, transepidermal water loss (TEWL), stratum corneum hydration and pH have been used to assess skin barrier function. However, few studies have determined their repeatability.

OBJECTIVE

To assess the repeatability of measurements of skin hydration, TEWL, pH, skin absorbance and erythema in healthy and atopic dogs.

ANIMALS

Fifteen healthy and 15 atopic privately owned dogs.

METHODS AND MATERIALS

Three repeated measurements using Corneometer®, Skin-pH-Meter®, Colorimeter® and VapoMeter® were obtained from inguinal, axilla, pinna and interdigital space by three investigators. Intra- and interobserver variability (coefficient of variation, correlation coefficients and intraclass correlation coefficients) and difference between the two groups (t-test or Mann-Whitney U-test) were determined.

RESULTS

High repeatability and low variation were observed both intra- and interobservers for all devices except the VapoMeter®. The most repeatable device was the Skin-pH-Meter®, whereas the VapoMeter® was the device with the highest intra- and interobserver variability. Atopic dogs had a significantly increased pH (inguinal P = 0.03; axilla P = 0.02) and erythema (inguinal P = 0.01; axilla P = 0.02) compared to healthy dogs. No differences between the two groups were detected using the Corneometer®, VapoMeter® or Colorimeter® (tartrazine absorption).

CONCLUSION AND CLINICAL SIGNIFICANCE

The results of this pilot study support the use of Corneometer®, Skin-pH-Meter® and Colorimeter® in the assessment of skin barrier function in dogs; further investigations to optimize measurements and confirm these results are needed.

The bacterial and fungal microbiome of the skin of healthy dogs and dogs with atopic dermatitis and the impact of topical antimicrobial therapy, an exploratory study

Canine atopic dermatitis is a genetically predisposed inflammatory and pruritic allergic skin disease that is often complicated by (secondary) bacterial and fungal (yeast) infections. High-throughput DNA sequencing was used to characterize the composition of the microbiome (bacteria and fungi) inhabiting specific sites of skin in healthy dogs and dogs with atopic dermatitis (AD) before and after topical antimicrobial treatment. Skin microbiome samples were collected from six healthy control dogs and three dogs spontaneously affected by AD by swabbing at (non-) predilection sites before, during and after treatment. Bacteria and fungi were profiled by Illumina sequencing of the 16S ribosomal RNA gene of bacteria (16S) and the internally transcribed spacer of the ribosomal gene cassette in fungi (ITS). The total cohort of dogs showed a high diversity of microbes on skin with a strong individual variability of both 16S and ITS profiles. The genera of Staphylococcus and Porphyromonas were dominantly present both on atopic and healthy skin and across all skin sites studied. In addition, bacterial and fungal alpha diversity were similar at the different skin sites. The topical antimicrobial treatment increased the diversity of bacterial and fungal compositions in course of time on both AD and healthy skin.

Microbiota profiling with long amplicons using Nanopore sequencing: full-length 16S rRNA gene and whole rrn operon

Background: Profiling the microbiome of low-biomass samples is challenging for metagenomics since these samples often contain DNA from other sources, such as the host or the environment. The usual approach is sequencing specific hypervariable regions of the 16S rRNA gene, which fails to assign taxonomy to genus and species level. Here, we aim to assess long-amplicon PCR-based approaches for assigning taxonomy at the genus and species level. We use Nanopore sequencing with two different markers: full-length 16S rRNA (~1,500 bp) and the whole rrn operon (16S rRNA-ITS-23S rRNA; 4,500 bp). Methods: We sequenced a clinical isolate of Staphylococcus pseudintermedius, two mock communities (HM-783D, Bei Resources; D6306, ZymoBIOMICS™) and two pools of low-biomass samples (dog skin from either the chin or dorsal back), using the MinION™ sequencer 1D PCR barcoding kit. Sequences were pre-processed, and data were analyzed using the WIMP workflow on EPI2ME or Minimap2 software with rrn database. Results: The full-length 16S rRNA and the rrn operon were used to retrieve the microbiota composition at the genus and species level from the bacterial isolate, mock communities and complex skin samples. For the Staphylococcus pseudintermedius isolate, when using EPI2ME, the amplicons were assigned to the correct bacterial species in ~98% of the cases with the rrn operon marker, and in ~68% of the cases with the 16S rRNA gene. In both skin microbiota samples, we detected many species with an environmental origin. In chin, we found different Pseudomonas species in high abundance, whereas in dorsal skin there were more taxa with lower abundances. Conclusions: Both full-length 16S rRNA and the rrn operon retrieved the microbiota composition of simple and complex microbial communities, even from the low-biomass samples such as dog skin. For an increased resolution at the species level, using the rrn operon would be the best choice.

Microbiota profiling with long amplicons using Nanopore sequencing: full-length 16S rRNA gene and the 16S-ITS-23S of the rrn operon

Background: Profiling the microbiome of low-biomass samples is challenging for metagenomics since these samples are prone to contain DNA from other sources (e.g. host or environment). The usual approach is sequencing short regions of the 16S rRNA gene, which fails to assign taxonomy to genus and species level. To achieve an increased taxonomic resolution, we aim to develop long-amplicon PCR-based approaches using Nanopore sequencing. We assessed two different genetic markers: the full-length 16S rRNA (~1,500 bp) and the 16S-ITS-23S region from the rrn operon (4,300 bp). Methods: We sequenced a clinical isolate of Staphylococcus pseudintermedius, two mock communities and two pools of low-biomass samples (dog skin). Nanopore sequencing was performed on MinION™ using the 1D PCR barcoding kit. Sequences were pre-processed, and data were analyzed using EPI2ME or Minimap2 with rrn database. Consensus sequences of the 16S-ITS-23S genetic marker were obtained using canu. Results: The full-length 16S rRNA and the 16S-ITS-23S region of the rrn operon were used to retrieve the microbiota composition of the samples at the genus and species level. For the Staphylococcus pseudintermedius isolate, the amplicons were assigned to the correct bacterial species in ~98% of the cases with the16S-ITS-23S genetic marker, and in ~68%, with the 16S rRNA gene when using EPI2ME. Using mock communities, we found that the full-length 16S rRNA gene represented better the abundances of a microbial community; whereas, 16S-ITS-23S obtained better resolution at the species level. Finally, we characterized low-biomass skin microbiota samples and detected species with an environmental origin. Conclusions: Both full-length 16S rRNA and the 16S-ITS-23S of the rrn operon retrieved the microbiota composition of simple and complex microbial communities, even from the low-biomass samples such as dog skin. For an increased resolution at the species level, targeting the 16S-ITS-23S of the rrn operon would be the best choice.

Novel association of Psychrobacter and Pseudomonas with malodour in bloodhound dogs, and the effects of a topical product composed of essential oils and plant-derived essential fatty acids in a randomized, blinded, placebo-controlled study

BACKGROUND

The pathogenesis and treatment of cutaneous malodour in dogs have not been investigated previously. Staphylococcus and Corynebacterium spp. are associated with human axillary malodour.

HYPOTHESIS

Staphylococcus and Corynebacterium spp. are associated with cutaneous malodour in dogs, and treatment with a topical essential oil-based product will improve malodour and reduce the abundance of odour-causing bacteria.

ANIMALS

Twenty seven bloodhound dogs from a south Texas boarding facility were enrolled in this study.

METHODS AND MATERIALS

Skin swabs were taken from the axilla and dorsum of 27 dogs at initiation of the study. Mean malodour scores were used to assign dogs to control or malodour groups. The malodourous dogs were randomly assigned to a treatment or placebo group, received four weekly topical applications of the spot-on or placebo, and samples were recollected. Next-generation sequencing (NGS) and real-time quantitative PCR (qPCR) were performed on all swabs.

RESULTS

Psychrobacter and Pseudomonas spp. were significantly more abundant (P < 0.001, P = 0.006; respectively), and overall bacterial diversity was reduced (P = 0.0384) on the skin of malodourous dogs. Staphylococcus and Corynebacterium spp. were not associated with malodour. The topical essential oil-based product significantly (P = 0.0078) improved malodour in the treatment group and shifted their bacterial community structure.

CONCLUSIONS AND CLINICAL IMPORTANCE

A novel association of bacterial genera with malodour in bloodhound dogs, identified by NGS, highlights future targets for odour control. The topical treatment significantly reduced malodour. The interaction between the topical treatment and cutaneous microbiota should be further investigated and may be useful in other dermatological conditions involving microbiota.

Glucocorticosteroids and ciclosporin do not significantly impact canine cutaneous microbiota

Background

As prednisone and ciclosporin can have immunosuppressive effects and have been considered potential predisposing factors for skin infections, we investigated the impact of these drugs on the diversity of the cutaneous microbiota, the abundance of Malassezia and infection with Papillomaviruses.

Results

Six atopic, asymptomatic Maltese-beagle dogs were treated with ciclosporin for one month and then with prednisone for another month, with a one-month wash-out between treatments. The dogs were sampled on the abdomen and pinna before and after each treatment using a swab. Samples for Papillomavirus detection were obtained with cytobrush sticks. The bacterial microbiota was characterized using 16S amplicon high-throughput sequencing. Malassezia populations were quantified with nested real-time PCR targeting the ribosomal internal transcribed spacer 1. The diversity and composition of cutaneous microbiota was not impacted in a detectable manner by any of the treatments. As observed for the bacterial microbiota, Malassezia populations were not affected by treatment. Three dogs were positive for Papillomavirus at more than one timepoint, but an association with treatment was not apparent.

Conclusions

Ciclosporin and prednisone at doses used for the treatment of atopic dermatitis do not impact the canine cutaneous microbiota in a detectable manner.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1370-y) contains supplementary material, which is available to authorized users.

Outstanding animal studies in allergy II. From atopic barrier and microbiome to allergen-specific immunotherapy

Purpose of review

Animal studies published within the past 18 months were assessed, focusing on innate and specific immunomodulation, providing knowledge of high translational relevance for human atopic and allergic diseases.

Recent findings

Allergic companion animals represent alternative models, but most studies were done in mice. Atopic dermatitis mouse models were refined by the utilization of cytokines like IL-23 and relevant skin allergens or enzymes. A novel IL-6 reporter mouse allows biomonitoring of inflammation. Both skin pH and the (transferable) microflora have a pivotal role in modulating the skin barrier. The microflora of the gastrointestinal mucosa maintains tolerance to dietary compounds and can be disturbed by antiacid drugs. A key mouse study evidenced that dust from Amish households, but not from Hutterites protected mice against asthma. In studies on subcutaneous and sublingual allergen-specific immunotherapy, much focus was given on delivery and adjuvants, using poly-lacto-co-glycolic particles, CpGs, probiotics or Vitamin D3. The epicutaneous and intralymphatic routes showed promising results in mice and horses in terms of prophylactic and therapeutic allergy treatment.

Summary

In atopic dermatitis, food allergies and asthma, environmental factors, together with the resident microflora and barrier status, decide on sensitization versus tolerance. Also allergen-specific immunotherapy operates with immunomodulatory principles.

The Microbiota Regulates Immunity and Immunologic Diseases in Dogs and Cats

The complex commensal microbiota found on body surfaces controls immune responses and the development of allergic and inflammatory diseases. New genetic technologies permit investigators to determine the composition of the complex microbial populations found on these surfaces. Changes in the microbiota (dysbiosis) as a result of antibiotic use, diet, or other factors thus influence the development of many diseases in the dog and cat. The most important of these include chronic gastrointestinal disease; respiratory allergies, such as asthma; skin diseases, especially atopic dermatitis; and some autoimmune diseases.

Analysis of Bacterial and Fungal Nucleic Acid in Canine Sterile Granulomatous and Pyogranulomatous Dermatitis and Panniculitis

Next generation sequencing (NGS) studies are revealing a diverse microbiota on the skin of dogs. The skin microbiota of canine sterile granulomatous and pyogranulomatous dermatitis (SGPD) has yet to be investigated using NGS techniques. NGS targeting the 16S rRNA and ITS-1 region of bacterial and fungal DNA, respectively, were used to investigate if bacterial and fungal DNA were associated with skin lesions in cases of canine SGPD. The study included 20 formalin-fixed paraffin-embedded (FFPE) skin samples and 12 fresh samples from SGPD-affected dogs, and 10 FFPE and 10 fresh samples from healthy dogs. DNA was extracted from deep dermis and panniculus, and microbial DNA was amplified using primers targeting the bacterial 16S rRNA V1-V3 and fungal ITS-1 regions. The amplified DNA was utilized for NGS on an Illumina MiSeq instrument. The sequences were processed using QIIME. No differences in fungal or bacterial alpha diversity were observed between the SGPD and control samples. Beta diversity analysis demonstrated differences in the bacterial communities between SGPD and control, but not in the fungal communities. Compared to controls, the family Erysipelotrichaceae and genus Staphylococcus were significantly more abundant in the SGPD FFPE samples, and genus Corynebacterium were more abundant in fresh samples. The bacteria found to be more abundant in SGPD are common inhabitants of skin surfaces, and likely secondary contaminants in SGPD cases. This study provides additional evidence that SGPD lesions are likely sterile.

The role of the skin microbiome in atopic dermatitis: a systematic review

Dysbiosis is a hallmark of atopic dermatitis (AD). The composition of skin microbiome communities and the causality of dysbiosis in eczema have not been well established. The objective of this review is to describe the skin microbiome profile in AD and address whether there is a causal relationship between dysbiosis and AD. The protocol is registered in PROSPERO (CRD42016035813). We searched PubMed, Embase, Scopus and ClinicalTrials.gov for primary research studies applying culture-independent analysis on the microbiome on AD skin of humans and animal models. Two authors independently screened the full text of studies for eligibility and assessed risk of bias. Because of heterogeneity no quantitative synthesis was done. Of 5735 texts, 32 met the inclusion criteria (17 published: 11 human and six animal studies). The studies varied in quality and applied different methodology. The skin in AD had low bacterial diversity (lowest at dermatitis-involved sites) and three studies showed depletion of Malassezia spp. and high non-Malassezia fungal diversity. The relative abundance of Staphylococcus aureus and Staphylococcus epidermidis were elevated and other genera were reduced, including Propionibacterium. A mouse study indicated that dysbiosis is a driving factor in eczema pathogenesis. The data are not sufficiently robust for good characterization; however, dysbiosis in AD not only implicates Staphylococcus spp., but also microbes such as Propionibacterium and Malassezia. A causal role of dysbiosis in eczema in mice should encourage future studies to investigate if this also applies to humans. Other important aspects are temporal dynamics and the influence of methodology on microbiome data.

Individual signatures and environmental factors shape skin microbiota in healthy dogs

BACKGROUND

The individual, together with its environment, has been reported as the main force driving composition and structure of skin microbiota in healthy dogs. Therefore, one of the major concerns when analyzing canine skin microbiota is the likely influence of the environment. Despite the dense fur covering, certain skin diseases exhibit differential prevalence among skin sites, dog breeds, and individuals.

RESULTS

We have characterized the normal variability of dog skin microbiota in a well-controlled cohort of a large number of Golden-Labrador Retriever crossed dogs (N = 35) with similar ages, related genetic background, and a shared environment. We found that the individual drives the skin microbiota composition and structure followed by the skin site. The main bacterial classes inhabiting dog skin in this cohort are Gammaproteobacteria and Bacilli. We also detected bacteria associated to the environment on different dog skin sites that could be reflecting the different degrees of exposure of each skin site and each dog. Network analyses elucidated bacterial interactions within and between skin sites, especially in the chin, abdomen, axilla, and perianal region, with the highly shared interactions probably representing an anatomical, behavioral, or environmental component. When analyzing each skin site independently to assess host-specific factors, we found that temporality (season of birth and time spent in the kennel) affected all the skin sites and specially the inner pinna. The most abundant taxon driving this difference was Sphingomonas. We also found taxonomic differences among male and female dogs on the abdomen, axilla, and back.

CONCLUSIONS

We observed a large inter-individual variability and differences among skin sites. Host-specific variables, such as temporality or sex, were also shaping skin microbiota of healthy dogs, even in an environmental homogenous cohort.

Isotretinoin and lymecycline treatments modify the skin microbiota in acne

Oral retinoids and tetracyclines have a major role in acne treatment. Here, we report for the first time the effect of isotretinoin and lymecycline therapy on the skin microbiota in cheek, back and armpit swab samples of acne vulgaris patients using 16S ribosomal RNA (16S rRNA) gene amplicon sequencing. Propionibacterium acnes was the most common in sebaceous areas of healthy and untreated acne skin and more abundant in back than cheek samples. Five taxa, including a Streptococcus taxon, differed significantly between the cheek samples of healthy controls and acne patients, and acne severity was positively correlated with the abundance of Propionibacterium. Both treatments reduced clinical acne grades and the abundance of Propionibacterium, while the abundance of several other taxa was significantly higher in treated cheek samples compared with untreated ones. Less variation was observed in back samples and none in armpit samples. There were no differences in alpha diversity between control and acne patients in any of the sampled skin areas, but the diversity of the microbiota on the cheek and the back was significantly increased after acne treatments. This study provides insight into the skin microbiota in acne and how it is modulated by systemic acne treatment.

Diluted sodium hypochlorite (bleach) in dogs: antiseptic efficacy, local tolerability and in vitro effect on skin barrier function and inflammation

BACKGROUND

Diluted sodium hypochlorite represents an inexpensive and widely available topical antiseptic, but there are no tolerability and efficacy data in veterinary dermatology.

OBJECTIVES

To determine the in vivo antibacterial effect and tolerability of topical diluted bleach application and to assess its in vitro effect on skin barrier lipids and anti-inflammatory properties on keratinocytes.

METHODS

Topical hypochlorite at 0.05% and tap water were applied to both sides of the thorax of four healthy dogs. The anti-inflammatory effect on canine keratinocytes was determined by real-time polymerase chain reaction; skin barrier integrity was assessed by evaluating stratum corneum lipid changes in canine stratified epidermal constructs.

RESULTS

The cell viability of primary keratinocytes treated with water and diluted hypochlorite at 0.005 and 0.01%, reduced the percentage of viable cells by 10%. The exposure of primary keratinocytes to 0.005% diluted hypochlorite significantly reduced the induction of inflammatory genes chemokine ligand-2 (CCL2; P = 0.015) and thymus and activation-regulated chemokine (TARC/CCL17, P = 0.032). There were no changes in skin lipid ceramide and nonceramide fractions in stratified epidermal constructs cultured for 17 days with 0.05% hypochlorite. Topical hypochlorite at 0.05% and tap water were well-tolerated without signs of skin irritation. Although a marked reduction in bacterial counts was seen within 20 min of diluted bleach application compared to the tap water control, this was only marginally significant (P = 0.06).

CONCLUSIONS AND CLINICAL IMPORTANCE

The results indicate that a topical diluted bleach solution, at either 0.05 or 0.005% hypochlorite concentrations, is a well-tolerated antiseptic that also exhibits anti-inflammatory properties.

A blinded, randomized clinical trial evaluating the efficacy and safety of lokivetmab compared to ciclosporin in client-owned dogs with atopic dermatitis

BACKGROUND

Lokivetmab is an injectable anti-canine-IL-31 monoclonal antibody to treat clinical manifestations of atopic dermatitis (AD) in dogs.

HYPOTHESIS/OBJECTIVES

To characterize the efficacy and safety of lokivetmab, and to demonstrate its noninferiority to ciclosporin under field conditions.

ANIMALS

Dogs with chronic AD (n = 274) were enrolled from 40 practices in Belgium, The Netherlands, France and Germany.

METHODS

Animals were randomized (1:1) to oral ciclosporin (5 mg/kg/once daily) or monthly injectable lokivetmab (1-3.3 mg/kg) for three months. Eighty one animals that successfully completed the comparative phase were enrolled in a continuation phase receiving lokivetmab for an additional six months. Owners assessed pruritus on a Visual Analog Scale, skin lesions were assessed by veterinary investigators with a Canine AD Extent and Severity Index (CADESI-03) scale.

RESULTS

Lokivetmab was noninferior to ciclosporin for pruritus reduction on Day 28 (51.90% versus 43.72%). For Day 28 CADESI-03 percentage reduction, noninferiority of lokivetmab (54.17) versus ciclosporin (56.86%) was not achieved. At none of the time points were mean CADESI-03 scores significantly different between groups. Continued efficacy towards pruritus and lesions was demonstrated in the continuation phase where 76.3% of animals (n = 45) were assessed as 'normal' for pruritus at study end. No abnormal health events associated with lokivetmab were observed during the initial three month phase (142 dogs) or during the subsequent six month phase (81 dogs).

CONCLUSIONS AND CLINICAL IMPORTANCE

Lokivetmab at a minimum monthly dose of 1 mg/kg provided quick onset (within one day) of a lasting effect in reducing pruritus and skin lesions with a good safety profile.

Lactoferricin/verbascoside topical emulsion: a possible alternative treatment for atopic dermatitis in dogs

Atopic dermatitis affects 3-15% of the general dog population and it has been diagnosed by veterinarians up to 58% of dogs affected with skin disease. It is usually a life-long pathology which can be controlled, but it can be seldom cured. The present investigation describes a case study in which lactoferricin and verbascoside are part of a formulation to obtain a dermatological lotion for canine dermatitis treatment. The study was an open-label trial design of two-week treatment. Thirty-eight dogs (23 females and 15 males), with atopic dermatitis and secondary bacterial or yeast overgrowth have been included. During treatment period the total clinical score progressively decreased associated with an improvement in clinical signs. No adverse effects were reported in any of the treated dogs. The present research suggests that daily applications of tested emulsion are effective in reducing bacterial overgrowth and clinical signs in skin folds and atopic dermatitis.

Atopic Dermatitis in Animals and People: An Update and Comparative Review

Atopic dermatitis is an extremely common, pruritic, and frustrating disease to treat in both people and animals. Atopic dermatitis is multifactorial and results from complex interactions between genetic and environmental factors. Much progress has been done in recent years in terms of understanding the complex pathogenesis of this clinical syndrome and the identification of new treatments. As we learn more about it, we appreciate the striking similarities that exist in the clinical manifestations of this disease across species. Both in animals and people, atopic disease is becoming increasingly common and important similarities exist in terms of immunologic aberrations and the propensity for allergic sensitization. The purpose of this review is to highlight the most recent views on atopic dermatitis in both domestic species and in people emphasizing the similarities and the differences. A comparative approach can be beneficial in understanding the natural course of this disease and the variable response to existing therapies.

The feline skin microbiota: The bacteria inhabiting the skin of healthy and allergic cats

BACKGROUND

The skin is inhabited by a multitude of microorganisms. An imbalance of these microorganisms is associated with disease, however, the causal relationship between skin microbiota and disease remains unknown. To describe the cutaneous bacterial microbiota of cats and determine whether bacterial dysbiosis occurs on the skin of allergic cats, the skin surfaces on various regions of 11 healthy cats and 10 allergic cats were sampled.

METHODOLOGY/PRINCIPAL FINDINGS

Genomic DNA was extracted from skin swabs and sequenced using primers that target the V4 region of the bacterial 16S rRNA. The bacterial sequences from healthy cats revealed that there are differences in species diversity and richness between body sites and different epithelial surfaces. Bacterial communities preferred body site niches in the healthy cats, however, the bacterial communities on allergic cat skin tended to be more unique to the individual cat. Overall, the number of bacterial species was not significantly different between the two health status groups, however, the abundances of these bacterial species were different between healthy and allergic skin. Staphylococcus, in addition to other taxa, was more abundant on allergic skin.

CONCLUSIONS/SIGNIFICANCE

This study reveals that there are more bacterial species inhabiting the skin of cats than previously thought and provide some evidence of an association between dysbiosis and skin disease.

Characterization of the urinary microbiome in healthy dogs

The urinary bladder in healthy dogs has dogmatically been considered free of bacteria. This study used culture independent techniques to characterize the healthy canine urinary microbiota. Urine samples collected by antepubic cystocentesis from dogs without urinary infection were used for DNA extraction. Genital tract and rectal samples were collected simultaneously from the same dogs. The V4 hypervariable region of the 16S rRNA bacterial gene was amplified and compared against Greengenes database for OTU assignment and relative abundance for urine, genital, and rectal samples. After excluding 4 dogs with cultivable bacteria, samples from 10 male (M; 1 intact) and 10 female (F) spayed dogs remained. All samples provided adequate genetic material for analysis. Four taxa (Pseudomonas sp., Acinetobacter sp., Sphingobium sp. and Bradyrhizobiaceae) dominated the urinary microbiota in all dogs of both sexes. These taxa were also detected in the genital swabs of both sexes, while the rectal microbiota differed substantially from the other sample sites. Principal component (PC) analysis of PC1 through PC3 showed overlap of urinary and genital microbiota and a clear separation of rectal swabs from the other sample sites along PC1, which explained 44.94% variation. Surprisingly, the urinary microbiota (mean # OTU 92.6 F, 90.2 M) was significantly richer than the genital (67.8 F, 66.6 M) or rectal microbiota (68.3 F, 71.2 M) (p < 0.0001), with no difference between sexes at any sample site. The canine urinary bladder is not a sterile environment and possesses its own unique and diverse microbiota compared to the rectal and genital microbiota. There was no difference between the sexes at any microbiota sample site (urine, genital, and rectal). The predominant bacterial genus for either sex in the urine and genital tracts was Pseudomonas sp.

A distinct bacterial dysbiosis associated skin inflammation in ovine footrot

Ovine footrot is a highly prevalent bacterial disease caused by Dichelobacter nodosus and characterised by the separation of the hoof horn from the underlying skin. The role of innate immune molecules and other bacterial communities in the development of footrot lesions remains unclear. This study shows a significant association between the high expression of IL1β and high D. nodosus load in footrot samples. Investigation of the microbial population identified distinct bacterial populations in the different disease stages and also depending on the level of inflammation. Treponema (34%), Mycoplasma (29%) and Porphyromonas (15%) were the most abundant genera associated with high levels of inflammation in footrot. In contrast, Acinetobacter (25%), Corynebacteria (17%) and Flavobacterium (17%) were the most abundant genera associated with high levels of inflammation in healthy feet. This demonstrates for the first time there is a distinct microbial community associated with footrot and high cytokine expression.

Individual Signatures Define Canine Skin Microbiota Composition and Variability

Dogs present almost all their skin sites covered by hair, but canine skin disorders are more common in certain skin sites and breeds. The goal of our study is to characterize the composition and variability of the skin microbiota in healthy dogs and to evaluate the effect of the breed, the skin site, and the individual. We have analyzed eight skin sites of nine healthy dogs from three different breeds by massive sequencing of 16S rRNA gene V1–V2 hypervariable regions. The main phyla inhabiting the skin microbiota in healthy dogs are Proteobacteria, Firmicutes, Fusobacteria, Actinobacteria, and Bacteroidetes. Our results suggest that skin microbiota composition pattern is individual specific, with some dogs presenting an even representation of the main phyla and other dogs with only a major phylum. The individual is the main force driving skin microbiota composition and diversity rather than the skin site or the breed. The individual is explaining 45% of the distances among samples, whereas skin site explains 19% and breed 9%. Moreover, analysis of similarities suggests a strong dissimilarity among individuals (R = 0.79, P = 0.001) that is mainly explained by low-abundant species in each dog. Skin site also plays a role: inner pinna presents the highest diversity value, whereas perianal region presents the lowest one and the most differentiated microbiota composition.