The feline cutaneous and oral microbiota are influenced by breed and environment

Analysis of the Culturable Skin Microbiome of Horses from Southern Germany

Horses have close interactions with humans and are important as working animals and livestock. In contrast to smaller companion animals like cats and dogs, there is only little information available about their skin microbiome. The objective of this study was to identify and characterize the culturable cutaneous microbiome of healthy horses. Samples were taken from 14 horses from Southern Germany which were randomly enrolled in this study. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a method to detect the culturable microorganisms of horse skin. The most abundant culturable species of horse skin identified in this study include Bacillus cereus, Bacillus pumilus, Carnobacterium inhibens, Exiguobacterium sibiricum, Macrococcus carouselicus, Macrococcus goetzii and Staphylococcus equorum. Analyses of the bacteria across different body regions indicated the specific preferences of species for certain skin areas. In addition, our data hinted to an influence of the age of the horses tested and an influence between the four stables studied.

Updates on the Pathogenesis of Canine Atopic Dermatitis and Feline Atopic Skin Syndrome: Part 2, the Skin Barrier, the Microbiome, and Immune System Dysfunction

Alterations in the lipid layer and intercellular corneocyte connections can lead to increased allergen penetration through the skin surface. A normal cutaneous microbiome keeps the opportunistic pathogen Staphylococcus pseudintermedius levels low, but allergic inflammation leads to decreased diversity and increase in S pseudintermedius. Keratinocytes sound the initial allergen alarm via cytokine signaling and promote T-helper 2 (Th-2) inflammation. Th-2 cytokine products IL-4, IL-13, and IL-31 are increased in the acute allergic inflammatory response. Altered response in T-helper 1, T-helper 17, and T-regulatory cells play a role in both acute and chronic allergic inflammation.

Case Report: Shift from Aggressive Periodontitis to Feline Chronic Gingivostomatitis Is Linked to Increased Microbial Diversity

Aggressive Periodontitis (AP) and Feline Chronic Gingivostomatitis (FCGS) are two oral inflammatory diseases in cats with unknown etiology. Both conditions present with severe inflammation of the oral cavity and in FCGS it is found with additional deterioration of the non-keratinized mucosa. The oral microbiome is increasingly implicated in disease progression, but little is known about shifts in the microbial community during the AP and FCGS progression. To that end, we used deep metagenomic sequencing with total RNA on three longitudinal samples of the oral microbiome in a cat first diagnosed with AP that progressed to FCGS. This deep sequencing approach revealed that increased diversity at both the genus and species levels marked the shift from AP to FCGS, including increases in Porphyromonas and Treponema species, and decreased Streptobacillus species. The metatranscriptomes were then probed for expression of antimicrobial resistance genes and virulence factors. Disease-related genes that include cheY, and ompP5 were expressed in early AP and FCGS, while others like galU were only expressed in one or the other disease state. Both genus and species-level shifts were observed along the longitudinal microbiome samples with a noted increase in species diversity in the FCGS-associated microbiome. Corroborating that functional shifts accompany taxonomic changes, the AMR and virulence factor expression similarly changed between the sampling points. Together, these taxonomic and functional shifts indicate that AP and FCGS are potentially linked and may be marked by changes in the oral microbiome, which supports the development of microbial-based clinical diagnostics and therapeutics.

Impacts of Antiretroviral Therapy on the Oral Microbiome and Periodontal Health of Feline Immunodeficiency Virus-Positive Cats

Feline immunodeficiency virus (FIV) is the domestic cat analogue of HIV infection in humans. Both viruses induce oral disease in untreated individuals, with clinical signs that include gingivitis and periodontal lesions. Oral disease manifestations in HIV patients are abated by highly effective combination antiretroviral therapy (cART), though certain oral manifestations persist despite therapy. Microorganisms associated with oral cavity opportunistic infections in patients with HIV cause similar pathologies in cats. To further develop this model, we evaluated characteristics of feline oral health and the oral microbiome during experimental FIV infection over an 8-month period following cART. Using 16S rRNA sequencing, we evaluated gingival bacterial communities at four timepoints in uninfected and FIV-infected cats treated with either cART or placebo. Comprehensive oral examinations were also conducted by a veterinary dental specialist over the experimental period. Gingival inflammation was higher in FIV-infected cats treated with placebo compared to cART-treated cats and the controls at the study endpoint. Oral microbiome alpha diversity increased in all groups, while beta diversity differed among treatment groups, documenting a significant effect of cART therapy on microbiome community composition. This finding has not previously been reported, and indicates cART ameliorates immunodeficiency virus-associated oral disease via the preservation of oral mucosal microbiota. Further, this study illustrates the value of the FIV animal model for investigations of mechanistic associations and therapeutic interventions for HIV's oral manifestations.

Revealing microbial community characteristics in healthy human, cat and canine salivas and looking for species-specific microbes

As two kinds of increasingly popular pets, the saliva of cat or canine is most likely to be left at the crime scene compared with the common types of body fluids in forensics. Accurately identifying the species of saliva samples found at the crime scene involving pets will help the investigators find available testing materials, reduce the consumption of reagents and save the investigative time of the case. Therefore, it is necessary to explore the characteristics and differences of saliva microbiomes of cat, canine and human. In this study, 16S rRNA gene amplicon sequencing technology was used to reveal microbial communities of saliva samples of healthy human, cat, and canine. Alpha diversity analyses indicated that canine saliva demonstrated the highest microbial diversity, followed by cat saliva, whereas human saliva microbial diversity was the lowest. The saliva samples of the three species all had their own unique microbial community compositions, and the dominant phyla of canine and cat salivas were Proteobacteria and Bacteroidete, while the dominant phyla of human saliva were Firmicutes and Proteobacteria. There was no significant statistical difference in the salivary microbiota obtained by the two collection methods (cotton swab and liquid saliva). The gender of cats and canines might have no effect on the salivary microbiota, but the different breeds had an impact on their saliva microbiomes. Principal coordinates analysis, non-metric multidimensional scaling analysis and random forest analysis all indicated significant differences in microbial community structures among the three species, allowing inference on the species sources of saliva samples by microbiome method. Differential microbial biomarkers for the salivas of three species were screened out using a variety of bioinformatics analyses, and the results demonstrated that Prevotella melaninogenica, Veillonella parvula, and Haemophilus parainfluenzae could be used as species-specific microbial biomarkers of human saliva. The detections of human species-specific microbes provide a potential method for determining human saliva.

The vaginal microbiota of healthy female cats

The vaginal microbiota of the queen (i.e., female cat) has never been described using culture independent methods. The objectives of the present research were to describe the vaginal microbiota of healthy domestic shorthair queens using both 16S rRNA sequencing and culture, and to assess the effects of age, living environment, and reproductive season on its composition. Thirty queens undergoing elective ovariectomy were included in the study. The vaginal samples were collected just before surgery, from animals under general anaesthesia. Two consecutive mini-swabs were introduced in the queens' vaginal tract. A preliminary study with 10 healthy queens aimed to negate sampling order's effect. Two consecutive samples for sequencing (5 queens, 10 swabs) and culture (5 queens, 10 swabs) were collected, confirming a match (100 % in culture, Bray-Curtis P = 0.96 in sequencing). The experiment included 20 queens that were prospectively grouped based on age (prepubertal N = 10, adult N = 10), living environment (indoor N = 10, outdoor N = 10), and time of the year, whether during the reproductive season (N = 10) or during seasonal anoestrous (N = 10). Bacteria were identified through metataxonomic analysis, amplifying the V1-V2 regions of 16S rRNA gene, and through standard culture followed by MALDI-TOF MS. The feline vaginal microbiota is dominated by Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria. Escherichia-Shigella, Streptococcus, and Pasteurella were the most abundant genera. Although culture underestimated bacterial richness and diversity compared to sequencing, Escherichia and Streptococcus were the most isolated bacteria. No bacterial growth was observed in 15 % of samples (N = 3/20), whereas growth of one or two bacterial species was observed in 64.7 % (N = 11/17) and 35.3 % (N = 6/17) of cases, respectively. No differences in terms of alpha (Kruskal-Wallis rank sum test P = 0.65) and beta diversity (Bray-Curtis, Unweighted and Weighted UniFrac analyses P > 0.5) were observed. Although a difference in alpha diversity based on phylogenetic tree (P = 0.02) was detected between indoor and outdoor queens. In conclusion, mixed and monoculture of Escherichia coli, Streptococcus canis, Staphylococcus felis, and Enterococcus spp. are normal findings within the cat vagina. Age and reproductive season do not influence the feline vaginal microbiota, whereas further research is needed to elucidate the role of the living environment.

Considerations for performing companion animal skin microbiome studies

The microbiome field has grown significantly in the past decade, and published studies have provided an overview of the microorganisms inhabiting the skin of companion animals. With the continued growth and interest in this field, concerns have been raised regarding sample collection methods, reagent contamination, data processing and environmental factors that may impair data interpretation (especially as related to low-biomass skin samples). In order to assure transparency, it is important to report all steps from sample collection to data analysis, including use of proper controls, and to make sequence data and sample metadata publicly available. Whilst interstudy variation will continue to exist, efforts to standardise methods will reduce confounding variables, and allow for reproducibility and comparability of results between studies. Companion animal microbiome studies often include clinical cases, and small sample sizes may result in lack of statistical significance within small datasets. The ability to combine results from standardised studies through meta-analyses would mitigate the limitations of these smaller studies, providing for more robust interpretation of results which could then inform clinical decisions. In this narrative review, we aim to present considerations for designing a study to evaluate the skin microbiome of companion animals, from conception to data analysis.

The polymicrobial nature of the oral cavity and claws of cats diagnosed by mass spectrometry and next-generation sequencing

Close contact between cats and humans increases the risk of transmission of zoonotic pathogens, through bites and scratches due to the complexity of microorganisms in the oral and nail microbiotas of felines. This study investigated the presence of bacteria and fungi in the oral cavity and claws of 100 apparently healthy cats using conventional and selective microbiological culture media, and next-generation sequencing (NGS) and mass spectrometry (MALDI-TOF MS). Furthermore, antimicrobial susceptibility testing of bacteria isolates was performed by disc diffusion method. In total, 671 bacteria and 33 yeasts were identified by MALDI-TOF MS. Neisseria animaloris (10.8 %), Staphylococcus felis (8.5 %), and Pasteurella multocida (7 %) were the most prevalent bacteria in oral cavity samples (n = 343), while the most common yeast (n = 19) was Candida albicans (68.4 %). Staphylococcus pettenkoferi (13.4 %), Staphylococcus felis (6.4 %), and Staphylococcus simulans (5.8 %) were the prevalent bacteria identified in the claw samples (n = 328), while Rhodotorula mucilaginosa (57.2 %) was the most common yeast (n = 14). NGS predominantly identified the genera Moraxella, Neisseria, Pasteurella, and Fusobacterium in oral cavity samples, whereas enterobacteria and staphylococci were prevalent in nail bed samples. In addition, the genera Capnocytophaga and Bartonella were identified, which have been described in serious human infections secondary to feline aggressions. Levofloxacin, marbofloxacin, and amoxicillin/clavulanic acid were the most effective drugs against the main groups of bacteria identified. Multidrug resistance was observed in 17 % of the bacterial isolates. Furthermore, three staphylococci harboring the methicillin resistance gene mecA were identified. We highlight the complexity of microorganisms inhabiting the oral/claw microbiotas of cats, the high resistance rate of the isolates to conventional antimicrobial agents, and the zoonotic risk of aggressions caused by bites and scratches from domestic cats.

Impacts of Antiretroviral Therapy on the Oral Microbiome and Periodontal Health of Feline Immunodeficiency Virus Positive Cats

Feline immunodeficiency virus (FIV) is the domestic cat analogue of HIV infection in humans. Both viruses induce oral disease in untreated individuals, with clinical signs that include gingivitis and periodontal lesions. Oral disease manifestations in HIV patients are abated by highly effective combination antiretroviral therapy (cART), though certain oral manifestations persist despite therapy. Microorganisms associated with oral cavity opportunistic infections in patients with HIV cause similar pathologies in cats. To further develop this model, we evaluated characteristics of feline oral health and oral microbiome during experimental FIV infection over an 8-month period following cART. Using 16S metagenomics sequencing, we evaluated gingival bacterial communities at four timepoints in uninfected and FIV-infected cats treated with cART or placebo. Comprehensive oral examinations were also conducted by a veterinary dental specialist over the experimental period. Gingival inflammation was higher in FIV-infected cats treated with placebo compared to cART-treated cats and controls at study endpoint. Oral microbiome alpha diversity increased in all groups, while beta diversity differed among treatment groups, documenting a significant effect of cART therapy on microbiome community composition. This finding has not previously been reported and indicates cART ameliorates immunodeficiency virus-associated oral disease via preservation of oral mucosal microbiota. Further, this study illustrates the value of the FIV animal model for investigations of mechanistic associations and therapeutic interventions for HIV oral manifestations.

Environment rather than breed or body site shapes the skin bacterial community of healthy sheep as revealed by metabarcoding

BACKGROUND

The skin is inhabited by a variety of micro-organisms, with bacteria representing the predominant taxon of the skin microbiome. In sheep, the skin bacterial community of healthy animals has been addressed in few studies, only with culture-based methods or sequencing of cloned amplicons.

OBJECTIVES

The objectives of this study were to determine the sheep skin bacterial community composition by using metabarcoding for a detailed characterisation and to determine the effect of body part, breed and environment.

MATERIALS AND METHODS

Overall, 267 samples were taken from 89 adult female sheep, belonging to three different breeds and kept on nine different farms in Switzerland. From every individual, one sample each was taken from belly, left ear and left leg and metabarcoding of the 16S rRNA V3-V4 hypervariable region was performed.

RESULTS

The main phyla identified were Actinobacteriota, Firmicutes, Proteobacteria and Bacteriodota. The alpha diversity as determined by Shannon's diversity index was significantly different between sheep from different farms. Beta diversity analysis by principal coordinate analysis (PCoA) showed clustering of the samples by farm and body site, while breed had only a marginal influence. A sparse partial least squares discriminant analysis (sPLS-DA) revealed seven main groups of operational taxonomic units (OTUs) of which groups of OTUs were specific for some farms.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings indicate that environment has a larger influence on skin microbial variability than breed, although the sampled breeds, the most abundant ones in Switzerland, are phenotypically similar. Future studies on the sheep skin microbiome may lead to novel insights in skin diseases and prevention.

Microbiota insights into pet ownership and human health

The relationship between pet and owner has already been studied in several studies. Reviewing and summarizing studies on human and pet microbiota and their effects due to keeping pets is the purpose of the current study. Microbiota of the gut, oral cavity, and skin are unique to each individual, and this is also true of their pets (cats and dogs). Microbiota homeostasis is essential for the health of pets and their owners. Dysbiosis or imbalances in the microbiota can increase the risk of disorder progressions such as IBD or Clostridium difficile infections, among others. The microbial communities of humans change as a result of various factors, such as keeping pets. Pet owners frequently contact domestic dogs and cats, which affects their microbiota. As a result of keeping pets, the microbiota of different areas of the human body has changed, which has been associated with a decrease in pathogenic bacteria and an increase in beneficial bacteria.

From wolves to humans: oral microbiome resistance to transfer across mammalian hosts

The mammalian mouth is colonized by complex microbial communities, adapted to specific niches, and in homeostasis with the host. Individual microbes interact metabolically and rely primarily on nutrients provided by the host, with which they have potentially co-evolved along the mammalian lineages. The oral environment is similar across mammals, but the diversity, specificity, and evolution of community structure in related or interacting mammals are little understood. Here, we compared the oral microbiomes of dogs with those of wild wolves and humans. In dogs, we found an increased microbial diversity relative to wolves, possibly related to the transition to omnivorous nutrition following domestication. This includes a larger diversity of Patescibacteria than previously reported in any other oral microbiota. The oral microbes are most distinct at bacterial species or strain levels, with few if any shared between humans and canids, while the close evolutionary relationship between wolves and dogs is reflected by numerous shared taxa. More taxa are shared at higher taxonomic levels including with humans, supporting their more ancestral common mammalian colonization followed by diversification. Phylogenies of selected oral bacterial lineages do not support stable human-dog microbial transfers but suggest diversification along mammalian lineages (apes and canids). Therefore, despite millennia of cohabitation and close interaction, the host and its native community controls and limits the assimilation of new microbes, even if closely related. Higher resolution metagenomic and microbial physiological studies, covering a larger mammalian diversity, should help understand how oral communities assemble, adapt, and interact with their hosts.IMPORTANCENumerous types of microbes colonize the mouth after birth and play important roles in maintaining oral health. When the microbiota-host homeostasis is perturbed, proliferation of some bacteria leads to diseases such as caries and periodontitis. Unlike the gut microbiome, the diversity of oral microbes across the mammalian evolutionary space is not understood. Our study compared the oral microbiomes of wild wolves, dogs, and apes (humans, chimpanzees, and bonobos), with the aim of identifying if microbes have been potentially exchanged between humans and dogs as a result of domestication and cohabitation. We found little if any evidence for such exchanges. The significance of our research is in finding that the oral microbiota and/or the host limit the acquisition of exogenous microbes, which is important in the context of natural exclusion of potential novel pathogens. We provide a framework for expanded higher-resolution studies across domestic and wild animals to understand resistance/resilience.

Aerococcus viridans and Public Health: Oral Carriage and Antimicrobial Resistance in Stray Dogs and Cats in Algeria

The current study aimed to determine the occurrence and antimicrobial resistance of oral Aerococcus viridans in stray dogs and cats in Algeria. Oral swabs from 200 stray animals (100 dogs and 100 cats) were collected and cultured on Columbia agar medium supplemented with 5% defibrinated sheep blood. Isolates were identified using analytical profile index Rapid 20 Strep commercial kits, and antibiotic susceptibility was determined using the disk diffusion method. Of the 200 animals sampled, 34 carried A. viridans in their oral cavities, with 26 isolates (76.47%) resistant to at least 2 drugs. Multidrug resistance profiles (to more than three different antimicrobials) were observed only in cats (26.08% of isolates). More isolates were resistant to erythromycin and tetracycline (71% and 65%, respectively) than to other antimicrobials. This is the first research study in Algeria detecting antimicrobial resistance in oral A. viridans isolated from dogs and cats and highlights potential public health concerns. Clinical trials registration number: 01/2018.

Antifungal susceptibility profile of yeasts isolated from the oral cavity of cats

BACKGROUND

Microorganisms living in the oral cavity play an important role in health and disease of the host. Cats are susceptible to oral infections, and it is documented that fungi in the oral cavity could impact these infections. Antifungal resistance has been increasing in recent years.

OBJECTIVES

This study was designed to identify yeast isolates from the oral cavity of healthy cats and to evaluate their antifungal susceptibility pattern.

METHODS

Oral specimens were collected from 60 cats and cultured at 37°C for 10 days. Yeasts were isolated and identified. Their antifungal susceptibility pattern was determined according to CLSI M44-A.

RESULTS

Three yeast genera were isolated, including Candida spp (55.5%), Rhodotorula spp (33.3%) and Hanseniaspora spp (11.1%). Antifungal susceptibility profiling showed that, apart from a dose-dependent effect of itraconazole, Hanseniaspora spp was susceptible to all seven drugs studied. The Candida species were susceptible to all drugs except ketoconazole (sensitivity 80%) and caspofungin (sensitivity 40%). In R. glutinis and R. minuta, 100% sensitivity was observed for amphotericin B, posaconazole, ketoconazole and voriconazole.

CONCLUSIONS

The results suggest that, in comparison with humans and other animals, cats have a different oral mycoflora in terms of species, number and diversity. However, these isolates have similar susceptibility patterns to those seen in isolates from other animals and humans. More studies should be done to further characterize the oral mycobiota of cats and its role in oral infections.

Hyphae, pseudohyphae, yeasts, spherules, spores, and more: A review on the morphology and pathology of fungal and oomycete infections in the skin of domestic animals

Fungi are among the most common infectious agents affecting the skin of animals. The skin can serve as a port of entry for fungal infections, which can eventually become disseminated. In some regions of the world, oomycetes, such as Pythium and Lagenidium, are also responsible for a significant number of severe cutaneous infections. Histologic evaluation of fungal morphology, including size, shape, septation, branching, and budding characteristics, combined with the distribution of inflammatory infiltrates within different skin layers can potentially identify etiologic agents, guiding selection of antifungals and additional diagnostics. Fungal infections of the skin surface are typically caused by Malassezia and rarely Candida, with opportunistic fungi also capable of colonizing the skin surface, especially when the barrier is broken. Folliculocentric infections, caused by dermatophytes, result in mild to severe inflammation and can occasionally penetrate deep into the skin. A wide range of fungi, including agents of hyalohyphomycosis, phaeohyphomycosis, and dimorphic fungal infections, as well as oomycetes, result in nodular cutaneous and subcutaneous lesions. With the occasional exception of dimorphic fungi, fungal speciation often requires cultures performed on fresh tissues. However, molecular techniques such as pan-fungal polymerase chain reaction on paraffin blocks is becoming an increasingly useful tool to distinguish between cutaneous fungal pathogens. This review focuses on describing the clinical and histologic features of the most common fungal and oomycete infections affecting the skin of animals, divided according to distribution patterns of lesions and fungal or oomycete morphology.

Colonization of methicillin-resistant Staphylococcus species in healthy and sick pets: prevalence and risk factors

BACKGROUND

The characterization of staphylococcal species that colonize pets is important to maintain animal health and to minimize the risk of transmission to owners. Here, the prevalence of Staphylococcus spp. and methicillin resistance was investigated in canine and feline isolates, and risk factors of staphylococcal colonization were determined. Pets were examined and separated into four groups: (1) healthy dogs, (2) healthy cats, and (3) dogs and (4) cats with clinical signs of bacterial infections of skin, mucous membranes, or wounds. Specimens were collected by a veterinary physician from six anatomic sites (external ear canal, conjunctival sacs, nares, mouth, skin [groin], and anus). In total, 274 animals (cats n = 161, dogs n = 113) were enrolled.

RESULTS

Staphylococcus species were highly diverse (23 species; 3 coagulase-positive and 20 coagulase-negative species), with the highest variety in healthy cats (19 species). The most frequent feline isolates were S. felis and S. epidermidis, while S. pseudintermedius was the most prevalent isolate in dogs. Risk factors of staphylococcal colonization included the presence of other animals in the same household, medical treatment within the last year, and a medical profession of at least one owner. Methicillin resistance was higher in coagulase-negative (17.86%) compared to coagulase-positive (1.95%) staphylococci. The highest prevalence of methicillin-resistant CoNS colonization was observed in animals kept in homes as the most common (dogs and cats).

CONCLUSIONS

The association of methicillin-resistant CoNS colonization with animals most often chosen as pets, represents a high risk of transmission between them and owners. The importance of nosocomial transmission of CoNS was also confirmed. This information could guide clinical decisions during the treatment of veterinary bacterial infections. In conclusion, the epidemiologic characteristics of CoNS and their pathogenicity in pets and humans require further research.

The feline skin microbiome: interrelationship between health and disease

PRACTICAL RELEVANCE

As with other species, the skin microbiome of cats has been assessed over the past few years utilizing modern technologies. This has resulted in the identification of many more bacterial and fungal organisms compared with what had been recorded historically on the skin in various states of health and disease using culture-based studies. This information is expanding the knowledge of how microbial communities are impacted by various changes in the skin health of cats. More specifically, how these microbial communities change in the face of health and disease, and how various therapeutic interventions affect the cutaneous microbiome, lends a greater understanding of disease pathogenesis and provides a growing area of research for correcting dysbiosis and improving feline skin health.

EVIDENCE BASE

Most studies on the feline skin microbiome thus far have been descriptive in nature. These provide a framework for the next level of investigations on how various states of health and disease impact the products produced by the cutaneous microbiome (ie, the cutaneous metabolome), as well as how targeted interventions may promote the restoration of balance.

AIMS

This review aims to summarize what is currently known about the feline cutaneous microbiome and its clinical implications. The role of the skin microbiome in health and disease, the current state of research in this area and the potential for future studies to produce targeted interventions for cats are a particular focus.

Challenging the Hypothesis of in Utero Microbiota Acquisition in Healthy Canine and Feline Pregnancies at Term: Preliminary Data

At present, there are no data on the presence of bacteria in healthy canine and feline pregnancies at term. Here, we investigated the uterine microbiome in bitches (n = 5) and queens (n = 3) undergoing elective cesarean section in two facilities. Samples included swabs from the endometrium, amniotic fluid, and meconium, and environmental swabs of the surgical tray as controls. Culture and 16S rRNA gene sequencing were used to investigate the presence of bacteria. Culture was positive for 34.3% of samples (uterus n = 3, amniotic fluid n = 2, meconium n = 4, controls n = 0), mostly with low growth of common contaminant bacteria. With sequencing techniques, the bacterial abundance was significantly lower than in environmental controls (p < 0.05). Sequencing results showed a species-specific pattern, and significant differences between canine and feline bacterial populations were found at order, family, and genus level. No differences were found in alpha and beta diversities between feto-maternal tissues and controls (p > 0.05). Dominant phyla were Bacteroidetes, Firmicutes, and Proteobacteria in different proportions based on tissue and species. Culture and sequencing results suggest that the bacterial biomass is very low in healthy canine and feline pregnancies at term, that bacteria likely originate from contamination from the dam's skin, and that the presence of viable bacteria could not be confirmed most of the time.

Environmental influences on childhood asthma: Allergens

Allergen exposure is associated with the development of allergen-specific sensitization, but their relationship is influenced by other contemporaneous exposures (such as microbial exposure) and the genetic predisposition of the host. Clinical outcomes of the primary prevention studies that tested the effectiveness of allergen avoidance in pregnancy and early life on the subsequent development of sensitization and asthma published to date are inconsistent. Therefore, we cannot provide any evidence-based advice on the use of allergen avoidance for the primary prevention of these conditions. The evidence about the impact of allergen exposure among and among sensitized children with asthma is more consistent, and the combination of sensitization and high exposure to sensitizing allergen increases airway inflammation, triggers symptoms, adversely impacts upon disease control, and is associated with poorer lung function in preschool age. However, there are differing opinions about the role of inhalant allergen avoidance in asthma management, and recommendations differ in different guidelines. Evidence from more recent high-quality trials suggests that mite allergen-impermeable bed encasings reduce hospital attendance with asthma attacks and that multifaceted targeted environmental control improves asthma control in children. We therefore suggest a pragmatic approach to allergen avoidance in the management of childhood asthma for clinical practice, including the recommendations to: (1) tailor the intervention to the patient's sensitization and exposure status by using titer of allergen-specific IgE antibodies and/or the size of the skin test as indicators of potential response; (2) use a multifaceted allergen control regime to reduce exposure as much as possible; and (3) start intervention as early as possible upon diagnosis.

Malassezia: Zoonotic Implications, Parallels and Differences in Colonization and Disease in Humans and Animals

Malassezia spp. are commensals of the skin, oral/sinonasal cavity, lower respiratory and gastrointestinal tract. Eighteen species have been recovered from humans, other mammals and birds. They can also be isolated from diverse environments, suggesting an evolutionary trajectory of adaption from an ecological niche in plants and soil to the mucocutaneous ecosystem of warm-blooded vertebrates. In humans, dogs and cats, Malassezia-associated dermatological conditions share some commonalities. Otomycosis is common in companion animals but is rare in humans. Systemic infections, which are increasingly reported in humans, have yet to be recognized in animals. Malassezia species have also been identified as pathogenetic contributors to some chronic human diseases. While Malassezia species are host-adapted, some species are zoophilic and can cause fungemia, with outbreaks in neonatal intensive care wards associated with temporary colonization of healthcare worker’s hands from contact with their pets. Although standardization is lacking, susceptibility testing is usually performed using a modified broth microdilution method. Antifungal susceptibility can vary depending on Malassezia species, body location, infection type, disease duration, presence of co-morbidities and immunosuppression. Antifungal resistance mechanisms include biofilm formation, mutations or overexpression of ERG11, overexpression of efflux pumps and gene rearrangements or overexpression in chromosome 4.

Perspectives and Advances in Probiotics and the Gut Microbiome in Companion Animals

As the number of households that raise dogs and cats is increasing, there is growing interest in animal health. The gut plays an important role in animal health. In particular, the microbiome in the gut is known to affect both the absorption and metabolism of nutrients and the protective functions of the host. Using probiotics on pets has beneficial effects, such as modulating the immune system, helping to reduce stress, protecting against pathogenic bacteria and developing growth performance. The goals of this review are to summarize the relationship between probiotics/the gut microbiome and animal health, to feature technology used for identifying the diversity of microbiota composition of canine and feline microbiota, and to discuss recent reports on probiotics in canines and felines and the safety issues associated with probiotics and the gut microbiome in companion animals.

Oral Microbiome in Dogs and Cats: Dysbiosis and the Utility of Antimicrobial Therapy in the Treatment of Periodontal Disease

Advances in gene sequence technology and data analysis have enabled the detection and taxonomic identification of microorganisms in vivo based on their unique RNA or DNA sequences. Standard culture techniques can only detect those organisms that readily grow on artificial media in vitro. Culture-independent technology has been used to provide a more accurate assessment of the richness (total number of species) and diversity (relative abundance of each species) of microorganisms present in a prescribed location. The microbiome has been defined as the genes and genomes of all microbial inhabitants within a defined environment. Microorganisms within a microbiome interact with each other as well as with the host. A microbiome is dynamic and may change over time as conditions within the defined environment become altered. In oral health, neither gingivitis nor periodontitis is present, and the host and microbiome coexist symbiotically without evoking an inflammatory response. The circumstances that cause a shift from immune tolerance to a proinflammatory response remain unknown, and a unified, all-encompassing hypothesis to explain how and why periodontal disease develops has yet to be described. The purpose of this review is to clarify the current understanding of the role played by the oral microbiome in dogs and cats, describe how the microbiome changes in periodontal disease, and offer guidance on the utility of systemic antimicrobial agents in the treatment of periodontitis in companion animals.

Oral bacterial DNA-based discrimination of human and canine saliva for the analysis of indistinct bite marks

Analyzing ambiguous bite marks using conventional morphological approaches to identify attackers is difficult; thus, applying molecular biological methods for identifying an attacker from their saliva is a possible approach in a forensic investigation. This study aimed to establish oral bacterial DNA-based human and canine saliva markers and develop a practical method for their discrimination. We considered Streptococcus oralis and Pasteurella canis as human and canine saliva marker candidates, respectively. Duplex bacterial DNA detection using melting curve analysis was designed and evaluated for forensic applicability using proof-of-concept experiments. S. oralis DNA was detected from human saliva samples from 30 out of 30 individuals, and P. canis DNA was detected from canine saliva samples from 73 out of 77 individuals (26 dog breeds). Additionally, both bacterial DNA markers were accurately detected from human blood-contaminated saliva samples and mock indistinct bite marks. Our results indicate that both bacterial DNA markers were sensitive, robust, and discriminating saliva markers. We consider that our duplex bacterial DNA examination is a simple, practical, and useful method for the detection of saliva from indistinct bite marks and discrimination between human and canine saliva.

Characterization of Oral Microbiota in Cats: Novel Insights on the Potential Role of Fungi in Feline Chronic Gingivostomatitis

Previous studies have suggested the involvement of viral and bacterial components in the initiation and progression of feline chronic gingivostomatitis (FCGS), but the role of fungi remains entirely unknown. This pilot study aimed to investigate the bacteriome and mycobiome in feline oral health and disease. Physical exams, including oral health assessment, of privately owned, clinically healthy (CH) cats (n = 14) and cats affected by FCGS (n = 14) were performed. Using a sterile swab, oral tissue surfaces of CH and FCGS cats were sampled and submitted for 16S rRNA and ITS-2 next-generation DNA sequencing. A high number of fungal species (n = 186) was detected, with Malassezia restricta, Malassezia arunalokei, Cladosporium penidielloides/salinae, and Aspergillaceae sp. being significantly enriched in FCGS samples, and Saccharomyces cerevisiae in CH samples. The bacteriome was significantly distinct between groups, and significant inter-kingdom interactions were documented. Bergeyella zoohelcum was identified as a potential biomarker of a healthy feline oral microbiome. These data suggest that fungi might play a role in the etiology and pathogenesis of FCGS, and that oral health should not simply be regarded as the absence of microbial infections. Instead, it may be viewed as the biological interactions between bacterial and fungal populations that coexist to preserve a complex equilibrium in the microenvironment of the mouth. Additional investigations are needed to improve our understanding of the feline oral ecosystem and the potential interactions between viruses, bacteria, and fungi in FCGS.

Skin Microbiota of the Captive Giant Panda (Ailuropoda Melanoleuca) and the Distribution of Opportunistic Skin Disease-Associated Bacteria in Different Seasons

The giant panda is one of the rarest animals in the world. Skin diseases seriously endanger the health of giant panda and are considered the second major cause of its morbidity. Skin microbiota is a complex ecosystem, and the community structure and the pathogenic potential of bacteria on giant panda skin remain largely unclear. In order to understand the skin bacterial flora of captive giant pandas, the microbiota in giant panda skin samples collected during different seasons was profiled via 16S rRNA gene sequencing. In total, 522 genera from 53 bacterial phyla were detected, with Proteobacteria (40.5%), Actinobacteria (23.1%), Firmicutes (21.1%), Bacteroidetes (9.5%), Cyanobacteria (2.1%), and Thermi (1.2%) as the predominant phyla and Streptococcus (13.9%), Acinetobacter (9.2%), Staphylococcus (2.9%), Pseudomonas (5.9%), Dermacoccus (4.8%), Brachybacterium (2.9%), Escherichia (2.7%), Chryseobacterium (2.1%), Arthrobacter (1.6%), Kocuria (1.5%), Psychrobacter (1.2%), Deinococcus (1.1%), and Flavobacterium (1.1%) as the predominant genera. The results indicated that the diversity was lower in winter than in other seasons and higher in autumn than in other seasons, and the abundance in spring was significantly higher than that in other seasons. Several skin disease-associated bacteria were detected as opportunists in the skin microbiota of healthy giant pandas. In this study, the results indicated that the high diversity and abundance of the skin bacteria may have enhanced the occurrence of skin disease in autumn and spring and that skin disease-associated bacteria are the normal components of the skin microbiota.

Malassezia species dysbiosis in natural and allergen-induced atopic dermatitis in dogs

Malassezia dermatitis and otitis are recurrent features of canine atopic dermatitis, increasing the cost of care, and contributing to a reduced quality of life for the pet. The exact pathogenesis of secondary yeast infections in allergic dogs remains unclear, but some have proposed an overgrowth of M. pachydermatis to be one of the flare factors. The distribution of Malassezia populations on healthy and allergic canine skin has not been previously investigated using culture-independent methods. Skin swabs were collected from healthy, naturally affected allergic, and experimentally sensitized atopic dogs. From the extracted DNA, fungal next-generations sequencing (NGS) targeting the ITS region with phylogenetic analysis of sequences for species level classification, and Malassezia species-specific quantitative real-time polymerase chain reaction (qPCR) were performed. M. globosa was significantly more abundant on healthy canine skin by both methods (NGS P < .0001, qPCR P < .0001). M. restricta was significantly more abundant on healthy skin by NGS (P = .0023), and M. pachydermatis was significantly more abundant on naturally-affected allergic skin by NGS (P < .0001) and on allergen-induced atopic skin lesions by qPCR (P = .0015). Shifts in Malassezia populations were not observed in correlation with the development of allergen-induced skin lesions. Differences in the lipid dependency of predominant Malassezia commensals between groups suggests a role of the skin lipid content in driving community composition and raises questions of whether targeting skin lipids with therapeutics could promote healthy Malassezia populations on canine skin.

Characterization of the cutaneous mycobiota in Persian cats with severe dermatophytosis

BACKGROUND

Persian cats are predisposed to chronic and severe dermatophytosis. Alterations to the cutaneous microbiota are one potential contributor to this predisposition.

OBJECTIVES

To characterise the cutaneous and environmental fungal microbiota of Persian cats with chronic, severe dermatophytosis, and to compare the fungal microbiota of cats with and without dermatophytosis.

ANIMALS

Thirty-six client-owned cats, including 26 Persian cats and 10 domestic long hair (DLH) cats.

METHODS AND MATERIALS

Skin and home environment swabs were collected from Persian cats with severe, chronic dermatophytosis as well as groups of healthy control cats (Persian and DLH). Sequencing of the internal transcribed spacer 1 (ITS1) region was performed in addition to ITS1 quantitative PCR and fungal culture.

RESULTS

Next-generation sequencing (NGS) targeting the fungal ITS region detected Microsporum sp. DNA from all Persian cats diagnosed with dermatophytosis and from environmental samples of their homes. A significant difference in community structure was identified between cases and controls, largely resulting from the Microsporum spp. DNA in samples from affected cats. Persian cats with dermatophytosis do not exhibit decreased fungal diversity. NGS failed to identify dermatophyte DNA on two culture-positive asymptomatic Persian controls and identified Trichophyton rubrum DNA from a culture-negative asymptomatic Persian control.

CONCLUSIONS

Aside from M. canis, our results indicate that an underlying fungal dysbiosis is not likely to play a role in development of dermatophytosis in Persian cats. Other explanations for predisposition to this disease, such as a primary immunodeficiency, ineffective grooming or unique features of Persian cat hair should be investigated.

Differences in the Composition of Cultivable Aerobic and Facultative Anaerobic Oral Microbiota in Cats of Various Age Groups

The feline oral cavity is naturally inhabited by various microorganisms contributing to the maintenance of its oral health. The imbalance of oral microbiota or the presence of pathogenic agents can lead to secondary oral diseases. Various factors such as sex, diet, breed, environment and even age, affect the composition of a healthy oral microbiota during the life of cats. The purpose of this study was to compare the composition of culturable aerobic and facultative anaerobic micro-biota in cats in terms of different age categories. We used conventional cultivation methods in conjunction with microscopic and biochemical methods to isolate and identify the micro organisms found in the oral cavity of cats. The examination of 76 samples confirmed the dominance of the phylum Proteobacteria in almost all groups. Commonly occurring bacteria have been identified, i. e. Streptococcus spp., Neisseria spp. and Pasteurella spp. Although aerobic and facultative anaerobic oral micro biota were examined, differences between age groups were noted. The microbial diversity of the oral microbiota significantly increased with age.

Preliminary functional analysis of the subgingival microbiota of cats with periodontitis and feline chronic gingivostomatitis

The subgingival microbial communities of domestic cats remain incompletely characterized and it is unknown whether their functional profiles are associated with disease. In this study, we used a shotgun metagenomic approach to explore the functional potential of subgingival microbial communities in client-owned cats, comparing findings between periodontally healthy cats and cats with naturally occurring chronic periodontitis, aggressive periodontitis, and feline chronic gingivostomatitis. Subgingival samples were subjected to shotgun sequencing and the metagenomic datasets were analyzed using the MG-RAST metagenomic analysis server and STAMP v2.1.3 (Statistical Analysis of Metagenomic Profiles) software. The microbial composition was also described to better understand the predicted features of the communities. The Respiration category in the level 1 Subsystems database varied significantly among groups. In this category, the abundance of V-Type ATP-synthase and Biogenesis of cytochrome c oxidases were significantly enriched in the diseased and in the healthy groups, respectively. Both features have been previously described in periodontal studies in people and are in consonance with the microbial composition of feline subgingival sites. In addition, the narH (nitrate reductase) gene frequency, identified using the KEGG Orthology database, was significantly increased in the healthy group. The results of this study provide preliminary functional insights of the microbial communities associated with periodontitis in domestic cats and suggest that the ATP-synthase and nitrate-nitrite-NO pathways may represent appropriate targets for the treatment of this common disease.

Evaluation of the ocular surface mycobiota in clinically normal horses

The eye is host to myriad bacterial, fungal, and viral organisms that likely influence ocular surface physiology in normal and diseased states. The ocular surface mycobiota of horses has not yet been described using NGS techniques. This study aimed to characterize the ocular surface fungal microbiota (mycobiota) in healthy horses in 2 environmental conditions (stalled versus pasture). Conjunctival swabs of both eyes were obtained from 7 adult stallions stabled in an open-air pavilion and 5 adult mares living on pasture. Genomic DNA was extracted from ocular surface swabs and sequenced using primers that target the Internal Transcribed Spacer 1 (ITS1) region of the fungal genome on an Illumina platform. Sequences were processed using Quantitative Insights Into Molecular Ecology (QIIME 2.0) and taxonomy assigned with the Findley et al. 2013 ITS1 database. The most abundant genera identified were Leptosphaerulina (22.7%), unclassified Pleosporaceae (17.3%), Cladosporium (16.2%), Alternaria (9.8%), unclassified Pleosporales (4.4%), unclassified Montagnulaceae (2.9%), Fusarium (2.5%), and Pestalotiopsis (1.4%). Fungal community composition (Jaccard, R = 0.460, p = 0.001) and structure (Bray-Curtis, R = 0.811, p = 0.001) were significantly different between pastured mares and stabled stallions. The ocular surface of pastured mares had significantly increased fungal species richness and diversity compared to stabled stallions (Shannon p = 0.0224, Chao1 p = 0.0118, Observed OTUs p = 0.0241). Relative abundances of Aspergillus (p = 0.005) and Alternaria spp. (p = 0.002) were significantly increased in the mycobiota of pastured mares. This is the first report to describe the mycobiota of the equine ocular surface. Environmental factors such as housing influence the composition, structure, and richness of the equine ocular surface mycobiota.

Oral flora of stray dogs and cats in Algeria: Pasteurella and other zoonotic bacteria

Background and Aim:

Knowledge of potentially pathogenic bacteria presents in the oral cavity of dogs and cats may be helpful in determining appropriate treatment for infected bite wounds. About 120.000 people are exposed to dog and cat bites every year in Algeria, but little is known about the dog and cat oral flora causing bite wound complications. The purpose of this study was to identify potential zoonotic bacteria from oral cavity of dogs and cats and to determine their susceptibility to antibiotics to contribute to the treatment of bite wound infection.

Materials and Methods:

Oral swabs from 100 stray dogs and 100 stray cats were collected and cultured in several media: Chocolate agar, MacConkey agar, and Mannitol Salt Agar. Bacterial isolates were identified using several commercial kits of the analytical profile index and tested for antibiotic susceptibility by disk diffusion method.

Results:

Overall, 185/200 (92.5%) dogs and cats carried zoonotic bacteria in their mouths, of which 55.13% (102/185) had at least two bacterial pathogens. 374 pathogenic strains belonging to 15 genera were isolated: Eleven were Gram-negative (Proteus, Pasteurella, Escherichia, Moraxella, Klebsiella, Acinetobacter, Enterobacter, Pseudomonas, Aeromonas, and NeisseriaHaemophilus) and four were Gram-positive (Staphylococcus, Streptococcus, and Corynebacterium, Bacillus). Fifty-one strains of Pasteurella were isolated from 44 carriers of Pasteurella (21 Pasteurella multocida, 21 Pasteurella pneumotropica, and 9 Pasteurella spp.). Pasteurella strains were tested for antibiotic resistance. Resistance to at least one drug was observed in 8 (15.68%) of Pasteurella isolates and two strains (3.92%) were found to be multidrug-resistant (to two or more drugs). Erythromycin, penicillin, and ampicillin were the antimicrobials to which the isolates showed greater resistance (7.84%, 5.88%, and 3.92%, respectively).

Conclusion:

To the best of our knowledge, this study is the first in Algeria to detect potential human pathogenic bacteria in the oral cavity of dogs and cats. It reveals that these animals have multiple zoonotic bacteria in their mouths including Pasteurella species, which may be multidrug-resistant.

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.

Streptobacillus felis, a member of the oropharynx microbiota of the Felidae, isolated from a tropical rusty-spotted cat

Streptobacillus felis is a fastidious microorganism and a novel member of the potentially zoonotic bacteria causing rat bite fever. Since its description, this is the second isolation of S. felis in a diseased member of the Felidae. Interestingly, the strain from this study was isolated from a zoo held, rusty-spotted cat (Prionailurus rubiginosus), with pneumonia, thereby indicating a possible broader host range in feline species. A recent preliminary sampling of domestic cats (Felis silvestris forma catus) revealed that this microorganism is common in the oropharynx, suggesting that S. felis is a member of their normal microbiota. Due to unawareness, fastidiousness, antibiotic sensitivity and lack of diagnostics the role of S. felis as a cat and human pathogen might be under-reported as with other Streptobacillus infections. More studies are necessary to elucidate the role of S. felis in domestic cats and other Felidae in order to better estimate its zoonotic potential.

The Effects of Nutrition on the Gastrointestinal Microbiome of Cats and Dogs: Impact on Health and Disease

The gastrointestinal (GI) microbiome of cats and dogs is increasingly recognized as a metabolically active organ inextricably linked to pet health. Food serves as a substrate for the GI microbiome of cats and dogs and plays a significant role in defining the composition and metabolism of the GI microbiome. The microbiome, in turn, facilitates the host's nutrient digestion and the production of postbiotics, which are bacterially derived compounds that can influence pet health. Consequently, pet owners have a role in shaping the microbiome of cats and dogs through the food they choose to provide. Yet, a clear understanding of the impact these food choices have on the microbiome, and thus on the overall health of the pet, is lacking. Pet foods are formulated to contain the typical nutritional building blocks of carbohydrates, proteins, and fats, but increasingly include microbiome-targeted ingredients, such as prebiotics and probiotics. Each of these categories, as well as their relative proportions in food, can affect the composition and/or function of the microbiome. Accumulating evidence suggests that dietary components may impact not only GI disease, but also allergies, oral health, weight management, diabetes, and kidney disease through changes in the GI microbiome. Until recently, the focus of microbiome research was to characterize alterations in microbiome composition in disease states, while less research effort has been devoted to understanding how changes in nutrition can influence pet health by modifying the microbiome function. This review summarizes the impact of pet food nutritional components on the composition and function of the microbiome and examines evidence for the role of nutrition in impacting host health through the microbiome in a variety of disease states. Understanding how nutrition can modulate GI microbiome composition and function may reveal new avenues for enhancing the health and resilience of cats and dogs.

Exploration of the microbiome community for saliva, skin, and a mixture of both from a population living in Guangdong

The identification of biological traces provides vital evidence in forensic reconstruction at crime scenes, especially in sexual offences. Compared with traditional presumptive or confirmatory methods, the microbiome-based method has been proven to be of great value in body fluid identification. Mixture of body fluids or tissue is common in sexual assault cases; thus, it is essential to determine the sources of mixed samples. In this study, 60 samples consisting of skin, saliva, and a mixed model of saliva deposited on facial skin were collected from a population living in Guangdong. Through 16s rDNA high-throughput sequencing, we identified the predominant microbes in saliva samples, viz., Haemophilus parainfluenzae T3T1, Neisseria flava, Gemella haemolysans, Prevotella melaninogenica, and Actinomyces odontolyticus; in skin samples, Cutibacterium acnes and Corynebacterium tuberculostearicum were the predominant species. The microbial composition of the same body fluid or tissue is similar in different individuals. However, among different body fluids or tissue, the composition of microflora in saliva is more stable than that on skin. Additionally, the microbial community in the mixed model of saliva deposited on facial skin from the same and different individuals was clearly determined by the constituent fluids or tissue, apart from the differences among the donors. Overall, the microbiome-based method may have good potential as a tool for identifying single and mixed body fluid or tissue.

Malassezia Yeasts in Veterinary Dermatology: An Updated Overview

Lipophilic yeasts of the genus Malassezia are important skin commensals and opportunistic skin pathogens in a variety of animals. The species M. pachydermatis was first isolated from the skin of a captive Indian rhinoceros with an exfoliative dermatitis in 1925, recognized as an important otic pathogen of dogs in the 1950's, and finally accepted, after several years of controversy, as a common cause of canine dermatitis in the 1990's. Since then, there has been considerable research into the biology of Malassezia yeasts and their interaction with their animal hosts. In dogs and cats, M. pachydermatis is associated with ceruminous otitis externa and a "seborrhoeic" dermatitis, wherein pruritic, erythematous skin lesions, often with brown/black greasy, malodourous material matting hairs, preferentially develop in intertriginous areas. Skin disease is favored by folds, underlying hypersensitivity disorders, endocrinopathies, defects of cornification, and in cats, various visceral paraneoplastic syndromes. Diagnosis is based on detecting the yeast in compatible skin lesions, usually by cytology, and observing a clinical and mycological response to therapy. Treatment normally comprises topical or systemic azole therapy, often with miconazole-chlorhexidine shampoos or oral itraconazole or ketoconazole. Management of concurrent diseases is important to minimize relapses. Historically, wild-type Malassezia isolates from dogs and cats were typically susceptible to azoles, with the exception of fluconazole, but emerging azole resistance in field strains has recently been associated with either mutations or quadruplication of the ERG11 gene. These observations have prompted increased interest in alternative topical antifungal drugs, such as chlorhexidine, and various essential oils. Further clinical trials are awaited with interest.