Feline dermatophytosis: aspects pertinent to disease management in single and multiple cat situations

A prospective study evaluating the adhesive tape impression for the diagnosis of dermatophytosis in dogs and cats

BACKGROUND

Potential contagion and zoonotic risk make rapid diagnosis of dermatophytosis important amongst companion animals.

HYPOTHESIS/OBJECTIVES

To compare the adhesive tape impression (ATI), trichogram, Wood's lamp (WL) examination and fungal culture for diagnosis of dermatophytosis, and the ATI and trichogram for ease of use.

ANIMALS

Five dogs and 15 cats with consistent lesions, history and at least two positive dermatophyte test results.

MATERIALS AND METHODS

After WL examination, one representative lesion per patient was sampled for ATI, trichogram and fungal culture. Microscopic detection of fungal elements on ATI and trichogram were objectively and subjectively compared. The ability of all tests to correctly detect dermatophytosis, and the ability of ATI and trichogram to detect fungal elements in >20 high-powered fields (HPF) were compared using Fisher's exact tests.

RESULTS

ATI, trichogram, fungal culture and WL were positive in 100% (20 of 20), 90% (18 of 20), 95% (19 of 20) and 65% (13 of 20) of patients, respectively, with a significant difference between WL and ATI (p = 0.0499). Fungal culture revealed Microsporum. canis (n = 16), Nannizzia gypsea (n = 1), Trichophyton mentagrophytes (n = 1) and T. rubrum (n = 1). Fungal elements were detected in >20 HPF more frequently with ATI (18 of 20) than trichogram (11 of 20) (p = 0.017), and detection required careful scanning to distinguish from background debris more often with trichogram. Fungal elements were located with neutrophil clusters and keratinocyte rafts in addition to abnormal hair fragments more frequently on ATI.

CONCLUSIONS AND CLINICAL RELEVANCE

ATI had the highest ability to correctly diagnose dermatophytosis, and increased ease of detecting fungal elements compared to trichogram.

Dermatophytosis in domestic cats: Identification, and treatment in an Indian context

The surge in domestic cat adoption across India, particularly the rising preference for high-pedigree cats, coupled with environmental factors, has resulted in increased incidence of dermatophytosis among feline companions. Despite this growing concern, there is a noticeable scarcity of studies in India delving into the etiological factors contributing to dermatophytosis in cats. This disease is a threat to animal health and carries public health significance, given that cats are recognized reservoir hosts for Microsporum canis, a common dermatophyte affecting humans and animals. This study endeavours to identify the dermatophytes affecting cats and establish a standardized therapeutic regimen while accounting for the local stigma surrounding the regular bathing of cats. The study involved the examination of 82 cats presenting dermatological lesions, when subjected to cultural examination in dermatophyte test medium revealed 36 afflicted with dermatophytes. Isolates were presumptively identified by staining using lactophenol cotton blue, Chicago sky blue 6B, and Calcofluor white stains. Molecular-level identification of the isolates was confirmed through PCR-RFLP, amplifying the Internal Transcribed Spacer Sequence of 16 s rDNA, followed by restriction digestion using the Mva1 enzyme. Among the thirty-six isolates, 29 were identified as M. canis, while the remaining 7 were M. gypseum. The cases were categorized into five groups and treated with Lime Sulphur dip, 4 % chlorhexidine shampoo, a shampoo containing 2 % miconazole and 4 % chlorhexidine, oral itraconazole alone, and a combination of oral itraconazole with lime-Sulphur dip. Statistical analysis revealed that the response was notably swifter with lime Sulphur dip when considering only topical therapy. Moreover, the mycological cure was most expeditious when combining Lime Sulphur dip with oral itraconazole. These findings underscore the pivotal role of topical biocides in feline dermatophytosis treatment, potentially reducing the reliance on specific antifungals and thereby contributing to the mitigation of antimicrobial resistance emergence.

Dermatophytosis in cats: A comprehensive study on diagnostic methods and their accuracy

Background

Dermatophytosis is a contagious fungal infection that affects mainly cats. It poses significant challenges in veterinary medicine due to its zoonotic potential and impact on animal and public health. Rapid and reliable diagnosis is crucial for preventing the spread of the disease, guiding treatment decisions, and monitoring disease control efforts. Although there are several studies on diagnostic methods in feline dermatophytosis, the comparison between them from the same sample lacks data. The absence of a universally accepted gold standard diagnostic method highlights the need for a multifaceted approach to diagnosing feline dermatophytosis.

Aim

This study aims to assess the accuracy and efficacy of different diagnostic techniques comprehensively.

Methods

For this, 48 samples of cats were analyzed by dermoscopy, direct hair examination, fungal culture using various media (Mycosel, Sabouraud, and Dermatophyte Test Medium), and polymerase chain reaction (PCR).

Results

Direct examination and dermoscopy yielded unsatisfactory results. Mycosel and Sabouraud were suboptimal. DTM demonstrated superior selectivity, making it the most reliable among traditional methods. PCR was the top performer, exhibiting singular sensitivity, specificity, and accuracy.

Conclusion

The study suggests that PCR may be the preferred choice for diagnosing feline dermatophytosis in clinical practice, especially when rapid and accurate results are essential.

Superficial Zoonotic Mycoses in Humans Associated with Cats

Dermatophytosis is a superficial fungal skin infection common in humans around the world and is one of the many zoonotic skin diseases that cat owners are at risk of contracting. This retrospective study was conducted based on a detailed analysis of the results of mycological examination and medical documentation of 56 patients diagnosed with cat-to-human dermatophytoses from January 2017 to July 2022. Zoonotic mycoses were diagnosed more frequently in young people and women. In children, lesions most often occurred in the scalp area, and in adults, in the glabrous skin area. Skin infections caused by Microsporum canis (M. canis) prevailed and were confirmed in 47 patients (83.9%). Trichophyton mentagrophytes (T. mentagrophytes) was found in nine (16.1%) patients. M. canis predominantly caused infections of the scalp, followed by lower limb infections. Hairy scalps were almost exclusively involved in children. The odds of diagnosing M. canis infection compared to T. mentagrophytes infection was significantly higher in the head than in other regions, especially among children. The positive predictive value of a direct macroscopic examination was relatively low.

Microbes on Clipper Blades after Use and Disinfection in Small Animal- and Equine Practice

Clipping hair on animals can produce microtraumas of the skin and the dislodgement of microorganisms to the clipper blade. This study evaluates if clipper blades in animal hospitals in Sweden are contaminated with bacteria and/or dermatophytes after disinfection. Eleven clipper blades from three veterinary referral hospitals, including one with a small animal department and an equine department, were sampled for bacteria and dermatophytes. All the hospitals had disinfection routines in accordance with the national recommendations for hygiene in veterinary medicine. The sampled clipper blades were supposed to be disinfected and they were considered to be ready for use by staff. Five sterilized clipper blades were used as controls. The results showed that 64-100% of the disinfected clipper blades, from all three hospitals, were contaminated with bacteria, whereas all the sterilized clipper blades were negative for bacterial growth (p < 0.05). One clipper blade from the equine department was contaminated with dermatophytes. The results indicate that the disinfection routines were not sufficient for removing bacteria from used clipper blades, and that sterilization would be a more reliable way to minimize the risk of contamination.

Reliability of using Wood's lamp by shelter personnel to diagnose Microsporum canis in cats

Optimising diagnostic methods in shelters so that they are as economical as possible for the shelter is especially important because shelters often have a significant lack of funds and so usually do not carry out preventive screening of cats. Dermatophyte fungi spread quickly and can infect shelter staff. The aim of our work was to identify the occurrence of Microsporum canis in shelter cats. It aimed to determine the prevalence of M. canis in cats at the selected shelter and compare the efficiency of detection using a Wood's lamp and culturing on Sabouraud's agar. All cats present in the shelter at the time of the study (n = 70) were examined with Wood's lamp and hair sampling followed by subsequent culturing on Sabouraud's agar. Identification of fungi was based on microscopic proof of macroconidia and microconidia. The prevalence of M. canis by diagnosis on Sabouraud's agar was 64.29% of cats, with the help of Wood's lamp 48.57% of cats showed positive fluorescence. The sensitivity of the Wood lamp examination was 71% and the specificity was 92%. Our study suggests that Wood's lamp could be used by trained shelter personnel for the first examination of cats at reception and could significantly reduce the risk of spreading M. canis in shelters.

Current Topics in Dermatophyte Classification and Clinical Diagnosis

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. Classification of many of these species has recently changed due to genetic analysis, potentially affecting clinical diagnosis and disease management. In this review, we discuss dermatophyte classification including name changes for medically important species, current and potential diagnostic techniques for detecting dermatophytes, and an in-depth review of Microsporum canis, a prevalent zoonotic dermatophyte. Fungal culture is still considered the “gold standard” for diagnosing dermatophytosis; however, modern molecular assays have overcome the main disadvantages of culture, allowing for tandem use with cultures. Further investigation into novel molecular assays for dermatophytosis is critical, especially for high-density populations where rapid diagnosis is essential for outbreak prevention. A frequently encountered dermatophyte in clinical settings is M. canis, which causes dermatophytosis in humans and cats. M. canis is adapting to its primary host (cats) as one of its mating types (MAT1-2) appears to be going extinct, leading to a loss of sexual reproduction. Investigating M. canis strains around the world can help elucidate the evolutionary trajectory of this fungi.

Rapid and Visual RPA-Cas12a Fluorescence Assay for Accurate Detection of Dermatophytes in Cats and Dogs

Dermatophytosis, an infectious disease caused by several fungi, can affect the hair, nails, and/or superficial layers of the skin and is of global significance. The most common dermatophytes in cats and dogs are Microsporum canis and Trichophyton mentagrophytes. Wood’s lamp examination, microscopic identification, and fungal culture are the conventional clinical diagnostic methods, while PCR (Polymerase Chain Reaction) and qPCR (Quantitative PCR) are playing an increasingly important role in the identification of dermatophytes. However, none of these methods could be applied to point-of-care testing (POCT). The recent development of the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) based diagnostic platform promises a rapid, accurate, and portable diagnostic tool. In this paper, we present a Cas12a-fluorescence assay to detect and differentiate the main dermatophytes in clinical samples with high specificity and sensitivity. The Cas12a-based assay was performed with a combination of recombinase polymerase amplification (RPA). The results could be directly visualized by naked eyes under blue light, and all tested samples were consistent with fungal culture and sequencing results. Compared with traditional methods, the RPA-Cas12a-fluorescence assay requires less time (about 30 min) and less complicated equipment, and the visual changes can be clearly observed with naked eyes, which is suitable for on-site clinical diagnosis.

Genetic Characterization of Microsporum canis Clinical Isolates in the United States

Microsporum canis is the primary agent causing dermatophytosis in cats, and also infects humans, dogs, and other species. Assessment of genetic variation among M. canis isolates in the United States has not been conducted. Further, M. canis mating type and assessment of disease severity associated with genotypic characteristics have not been rigorously evaluated. We therefore isolated M. canis from 191 domestic cats across the US and characterized genotypes by evaluation of ITS sequence, MAT locus, and microsatellite loci analysis. The genes SSU1 and SUB3, which are associated with keratin adhesion and digestion, were sequenced from a subset of isolates to evaluate potential genetic associations with virulence. Analysis of microsatellite makers revealed three M. canis genetic clusters. Both clinic location and disease severity were significant predictors of microsatellite variants. 100% of the M. canis isolates were MAT1-1 mating gene type, indicating that MAT1-2 is very rare or extinct in the US and that asexual reproduction is the dominant form of replication. No genetic variation at SSU1 and SUB3 was observed. These findings pave the way for novel testing modalities for M. canis and provide insights about transmission and ecology of this ubiquitous and relatively uncharacterized agent.

A retrospective analysis of the concordance of in-house fungal culture and a commercial quantitative PCR from 16 dermatology referral practices across the USA (2018-2019)

BACKGROUND

Commercial quantitative (q)PCR and fungal culture can be used concurrently or individually to test for dermatophytosis with a reported high sensitivity and specificity.

HYPOTHESIS/OBJECTIVES

The aims of this retrospective study were: (i) to evaluate the concordance of a commercial qPCR with in-house fungal culture for the initial diagnosis of dermatophytosis and for monitoring for mycological cure during treatment in dermatology private practice; and (ii) determine the sensitivity and specificity of qPCR overall, (iii) for initial diagnosis and (iv) for treatment monitoring in dogs and cats.

ANIMALS

Four-hundred and twenty-seven client-owned dogs and 188 client-owned cats.

MATERIALS AND METHODS

Retrospective evaluation of electronic medical records from 615 client-owned dogs and cats presented to 16 dermatology referral practices across the USA from 2018 to 2019. Concordance of qPCR with in-house fungal culture and sensitivity and specificity were determined from 667 paired samples.

RESULTS

qPCR agreed with in-house fungal culture in 63 of 85 positive tests and 571 of 582 negative tests, with an overall sensitivity and specificity of 74.1% [95% confidence interval (CI) 63.5-83.0] and 98.1% (95%CI 96.6-99.0), respectively. qPCR sensitivity and specificity for the initial diagnosis of dermatophytosis and for treatment monitoring were 72.4% (95%CI 59.1-83.3) and 98.7% (95%CI 97.3-99.5), and 77.8% (95%CI 57.7-91.4) and 92.0% (95%CI 80.1-97.8), respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Compared to in-house fungal culture, qPCR was less sensitive and more specific than reported previously. These findings suggest that a diagnosis of dermatophytosis and determining mycological cure should continue to be based on a combination of complementary diagnostic tests.

Two novel species of Arthroderma isolated from domestic cats with dermatophytosis in the United States

Dermatophytosis is a superficial fungal infection of keratinized tissues that can occur in humans and other animals. In domestic cats, the majority of cases are caused by Microsporum canis and can spread to other animals and humans via arthrospores. Between 2019 and 2021, 164 cases of suspected dermatophytosis were recorded in animals from a high-volume shelter in California. Samples (hair, nail, and skin scraping) were collected for routine screening from these individuals. One hundred and twenty-six of these were diagnosed as M. canis by culture and internal transcribed spacer (ITS) sequence. In four suspected dermatophytosis cases occurring in kittens in 2019, cultures grown at 20°C yielded fungi with colony morphology more similar to Arthroderma species than Microsporum. Morphologic and microscopic examinations were conducted, and gene segments for the ITS, β-tubulin, and translation elongation factor 1-alpha (TEF1) regions were sequenced from DNA extracted from these cultures. Sequences were aligned to other dermatophytes using maximum likelihood and neighbor-joining trees and were compared to previously described fungal species to assess nucleotide homology. We identified two previously undescribed fungal species, herein proposed as Arthroderma lilyanum sp. nov. and Arthroderma mcgillisianum sp. nov. M. canis co-cultured in two of the four cases. Other physiologic tests supported this diagnosis. These species have significance as potential pathogens and should be considered as rule-outs for dermatophytosis in cats. The potential for infection of other species, including humans, should be considered.

The influence of sample processing time on the performance of Microsporum canis cultures in cats

BACKGROUND

Fungal culture is widely used as a diagnostic tool for detecting dermatophytosis. However, the presence of fungal contaminants can influence the culture's performance and compromise the diagnosis.

OBJECTIVE

To verify whether the sample processing time can affect the performance of fungal culture for the diagnosis of Microsporum canis infection in cats.

ANIMALS

Forty Persian cats.

METHODS AND MATERIALS

Hair and scale samples were collected by combing the coat using a 5 × 5 cm sterile polyester carpet. The carpets were assigned randomly to four groups based on time point of processing samples after collection (i.e. used for culture on a selective agar medium for dermatophytes): Group 1: 8 h (n = 10); Group 2: 24 h (n = 10); Group 3: 48 h (n = 10); and Group 4: 72 h (n = 10). Cultures were compared regarding the degree of fungal invasion by either M. canis or nondermatophytic contaminant moulds (NDM).

RESULTS

Processing samples after 24 h of storage resulted in increased isolation rates of NDM and decreased isolation rates of M. canis. Samples processed after 48 h and 72 h presented more than half of the plates with a high degree of fungal contamination (i.e. NDM occupying ≥50% of the total fungal mass). However, samples processed after 8 h and 24 h presented a lower degree (P < 0.05) of NDM plate invasion and higher recovery rates of M. canis when compared to samples processed after 48 h and 72 h.

CONCLUSIONS AND CLINICAL IMPORTANCE

Delayed processing time is closely associated with the overgrowth of contaminants and with lower recovery rates of M. canis.

Survey of dermatophytes in stray dogs and cats with and without skin lesions in Puerto Rico and confirmed with MALDI-TOF MS

Dermatophytosis is a common and highly contagious zoonotic skin disease in companion animals. This disease is a major concern in geographical areas that contain large numbers of stray animal populations. Numerous surveys on dermatophytosis among stray animal populations worldwide range between 27% to 50%. In recent years, the US territory of Puerto Rico was impacted by several natural disasters such as hurricanes, which has led to a large increase of abandonment cases and an increase in the stray animal population. Due to this, large low-cost spay/neuter clinics and trap-neuter-release programs have become a more common practice on the island. During these events, veterinary staff are exposed to multiple animals with no health history, and therefore, zoonotic diseases are of concern. The aim of this study was to provide information regarding the presence of dermatophyte species in symptomatic and asymptomatic stray dogs and cats in a region of Puerto Rico. Hair samples were collected from 99 stray animals with and without dermatological clinical signs. The hair samples were cultured on plates containing rapid sporulation medium and dermatophyte test medium. All cultures were evaluated microscopically to confirm the presence of dermatophytes. Then, all dermatophytes were further evaluated with MALDI-TOF MS to compare both diagnostic tests. A total of 19 animals (19%) were positive for dermatophyte growth. Of these animals, 18/19 were infected with M. canis and 1/19 with Trichophyton spp. Animals with clinical lesions were positive only 13.5% of the time compared to asymptomatic animals, who were positive in 36% of the sample population. All 19 dermatophytes (100%) diagnosed with microscopic evaluation were confirmed with MALDI-TOF MS. Our results indicate that there is a prevalence of 19% of dermatophytosis among the stray dog and cat population of the southeastern coast of the island.

Presumptive Zoonotic Kerion by Nannizzia gypsea: Case Report

Nannizzia gypsea (formerly Microsporum gypseum) belongs to geophilic dermatophytes, fungi involved in keratin degradation in the soil; however, they are also found in dogs and cats. Transmission to humans can occur directly by contact with soil, but indirect transmission via domestic animals is reported too. The exact source of the infection is usually difficult to assess and in most cases only hypothesised and rarely investigated. This case report describes a kerion caused by N. gypsea in a 2-year-old boy, where the contagion was probably secondary to domestic healthy carrier dogs. A “One-Health” approach involving human dermatologists and veterinarians, combined with the use of conventional and molecular-based techniques, allowed tracing of the epidemiological chain and managing of not only the treatment but also the prevention of a recurrence. The child's lesion began to regress after about 8 weeks of treatment with both systemic and topical therapy, while the dogs were given chlorhexidine and miconazole baths. No recurrences nor new infections occurred, demonstrating the effectiveness of the strategies used.

Chronic Otitis in Cats: Clinical management of primary, predisposing and perpetuating factors

PRACTICAL RELEVANCE

Chronic otitis can be one of the most frustrating diseases to manage for a small animal practitioner. While it occurs less commonly in the cat than the dog, it is no less challenging. The purpose of this review is to discuss the common and uncommon causes of chronic otitis in the cat within the clinical framework used for diagnosis and treatment. The focus is on diseases that affect the ear canal, rather than those restricted to the pinnae.

CLINICAL CHALLENGES

Otitis is multifactorial, which complicates management. A common clinical mistake is to focus solely on treating the infection present. Only by addressing all factors will a clinician successfully control chronic otitis. For the purposes of this review, the authors have adopted the established model of separating primary, predisposing and perpetuating causes of otitis. Primary factors are those that directly cause otitis (inflammation); predisposing factors are those that put the patient at risk for development of otitis; and perpetuating factors are those that result in ongoing clinical signs of otitis or that prevent clinical resolution.

AUDIENCE

This review is aimed at veterinarians who treat cats and particularly those with an interest in feline dermatology and otology.

EQUIPMENT

While many practitioners rely on a hand-held otoscope, a video-otoscope can be very helpful for the diagnosis and treatment of chronic otitis.

EVIDENCE BASE

This review presents up-to-date information regarding the diagnosis and treatment of chronic otitis in cats, with emphasis on the most recent peer-reviewed literature.

Comparison of subclinical dermatophyte infection in short- and long-haired cats

Background and Aim

Long-haired cats may have an increased risk of dermatophytosis due to insufficient grooming and their thick hair coat trapping fungal spores. The prevalence of subclinical dermatophytosis in long-haired cats was evaluated using fungal culture and Wood's lamp test. Hematology and blood chemistry results were compared between cats negative and positive for dermatophytosis.

Materials and Methods

A total of 127 cats (median age, 3 years [range, 10 months-10 years]) without feline leukemia virus or feline immunodeficiency virus infection were classified into short-haired (n=64) and long-haired (n=63) groups. Hair samples were cultured on a fungal culture medium (dermatophyte test medium, enhanced sporulation agar, and Sabouraud agar).

Results

The prevalence of dermatophytosis in short-haired and long-haired cats was 6.25% (95% confidence interval [CI], 2.15-12.28) and 34.92% (95% CI, 22.94-46.90), respectively. The odds of long-haired cats having dermatophytosis were 8.05 (95% CI, 2.44-33.97) times greater than that in short-haired cats. The number of positive dermatophytosis found in domestic short-haired cats (2/50, 4.0%) was significantly lower than that in Persian cats (17/47, 36.17%; p<0.001) and long-haired mixed breed cats (3/7, 42.86%; p=0.011). The overall sensitivity and specificity of the Wood's lamp test for diagnosing Microsporum canis infection were 37.5% (95% CI, 21.2-57.3%) and 96.1% (95% CI, 90.4-98.5%), respectively. Cats with dermatophytosis had significantly lower hematocrit and serum albumin levels than cats without dermatophytosis.

Conclusion

Subclinical dermatophytosis was more common in long-haired cats; therefore, dermatophyte examinations should be performed routinely.

Isolation of dermatophytes from dogs and cats in the South of England between 1991 and 2017

BACKGROUND

Since the epidemiology of canine and feline dermatophytosis might evolve in response to chronological, sociological and ecological factors, the authors studied the occurrence of dermatophyte pathogens over 27 years subsequent to the last major UK survey.

METHODS

Dermatophyte culture submission records from dogs and cats to the Royal Veterinary College Diagnostic Laboratory in England between 1991 and 2017 were reviewed. Samples were routinely cultured aerobically at 26°C for up to four weeks on Sabouraud's dextrose agar containing cycloheximide and chloramphenicol; dermatophytes were identified using conventional phenotypic methods.

RESULTS

Proportional isolation from cats (15.9 per cent of 1389) exceeded that of dogs (8.1 per cent of 2193) (P<0.001). Together, Microsporum canis and Trichophyton mentagrophytes accounted for 91.9 per cent (n=203) and 80.2 per cent (n=142) of isolations from cats and dogs, respectively. M canis was more frequently (P<0.001) isolated from cats and dogs under two years of age. Dermatophytes were more frequent (P≤0.001) in samples from first-opinion rather than referral practice, and from Jack Russell and Yorkshire terriers and from Persian and chinchilla cats (P≤0.002).

CONCLUSIONS

M canis and T mentagrophytes remain the most common agents of canine and feline dermatophytosis in the South of England; continued clinical vigilance is required.

Descriptive epidemiology of companion animal dermatophytosis in a Canadian Pacific Northwest animal shelter system

This study investigated the frequency of false positive dermatophyte cultures, dermatophyte prevalence, and dermatophytosis risk factors in an animal sheltering system in British Columbia. Records for 80 471 incoming shelter animals over 3.5 years were accessed retrospectively. For 831 high-risk animals cultured, the false positive rate was 28% [N = 229; 95% confidence interval (CI): 25% to 31%]. Microsporum canis was diagnosed in 201 cases (0.25%, 95% CI: 0.22% to 0.29%) and Trichophyton was diagnosed in 43 cases (0.055%, 95% CI: 0.040% to 0.072%). Microsporum canis cases occurred only in cats and rabbits, but not in dogs. Cats were twice as likely to be diagnosed with Trichophyton as dogs. Puppies and kittens (versus adults) and animals from cruelty investigations (versus other sources) were significantly more likely to be diagnosed with dermatophytosis. Animals seized from 4 cruelty cases with enzootic dermatophytosis did not follow overall prevalence or population risk patterns. Understanding patient and population risk factors can help expedite diagnosis, treatment, and recovery, and reduce contagious risk to humans and animals.

One vs two negative fungal cultures to confirm mycological cure in shelter cats treated for Microsporum canis dermatophytosis: a retrospective study

OBJECTIVES

The aim of this study was to determine how often one negative fungal culture (FC) was indicative of mycological cure (MC) when compared with two negative consecutive FCs in cats treated for Microsporum canis dermatophytosis.

METHODS

In this retrospective study, weekly FC data from shelter cats treated for M canis dermatophytosis were reviewed.

RESULTS

Complete records from 371 cats were reviewed. The first negative FC was indicative of MC in 335 (90.3%) cats. In this group, all cats were otherwise healthy and either had obvious lesions (n = 237) or no lesions or evidence of resolving lesions (n = 98). In the 36 cats in which the first negative culture was not indicative of MC, there were two clinical subgroups. The first consisted of healthy but lesional cats (n = 19) that had one negative FC within the first 3 weeks of treatment followed by one or more positive FCs. The most likely explanation was sampling error. These cats went on to cure and the next negative FC was indicative of MC. In the second clinical group, cats were lesional but had concurrent medical problems (n = 17). These cats showed an initial good response to treatment (lesion resolution and an initial negative FC). However, this negative FC was followed by at least one strongly positive FC (>10 colony-forming units/plate) before proceeding to cure. These cats took the longest time to cure (mean 11 weeks; range 8-28 weeks). MC occurred after resolution of the concurrent health issues. There was very good agreement between using one negative FC vs two negative FCs for the determination of MC in healthy cats (kappa = 0.903).

CONCLUSIONS AND RELEVANCE

In cats where there has been high compliance with environmental cleaning, as well as topical and systemic treatment recommendations, two consecutive negative FCs may not be necessary to determine MC. The first negative FC in an otherwise healthy cat is likely indicative of MC. Good sampling technique is needed to avoid false-negative FC results.

Systemic lime sulfur toxicosis secondary to dermal exposure in two cats

OBJECTIVE

To describe a case series of systemic lime sulfur toxicosis secondary to topical administration in 2 cats.

CASE SUMMARY

Two cats from the same household that were being previously treated for Microsporum canis were presented following topical administration of an incorrectly diluted lime sulfur dip. A 30% solution was used rather than the recommended 3% solution, resulting in a 10-fold concentration overdose. The cats presented to the emergency service 1 hour after dermal application of the lime sulfur product at home. The first cat, a 2-year-old female, intact Cornish Rex, had severe hypotension, bradycardia, and hypothermia. Chemical burns were also present on the ventrum and paws. Clinicopathological data revealed profound acid-base disturbances, hypercalcemia, hyperphosphatemia, and azotemia. After aggressive fluid resuscitation, electrolyte supplementation, and treatment, the patient was stabilized and discharged after 5 days of hospitalization; full recovery was later reported. The second littermate, also a 2-year-old female, intact Cornish Rex, presented the following day with similar clinical signs, physical examination findings, and clinicopathological findings. After supportive care and 2 days of hospitalization, the patient was also discharged and reported to fully recover.

NEW OR UNIQUE INFORMATION PROVIDED

This case series is the first to report systemic toxicosis secondary to dermal exposure of lime sulfur. As lime sulfur is commonly used in veterinary medicine for the treatment of ectoparasites, veterinary professionals should be aware of the significant signs of poisoning that can be seen as a result of iatrogenic dosing errors by pet owners or veterinary professionals.

Descriptive epidemiology and test characteristics of cats diagnosed with Microsporum canis dermatophytosis in a Northwestern US animal shelter

OBJECTIVES

The aims of this descriptive study were to identify risk factors for feline Microsporum canis infection at shelter intake, to describe screening test accuracy, and to refine confirmatory testing time frames.

METHODS

Database records for the general feline population and intake data, medical records and fungal culture logs for cats diagnosed with M canis at a limited admissions shelter were accessed retrospectively for a period of 2 years.

RESULTS

The feline population at the study shelter had a prevalence of M canis of 1.8% (95% confidence interval [CI] 1.6-2.0%). Kittens were eight (95% CI 4.8-13.5) times more likely to present with dermatophytosis than adults. Although more cats presented with M canis during summer and autumn, season was not significant when the model was controlled for age. Owner-surrendered cats were half as likely (95% CI 0.41-0.77) as transported cats to be diagnosed with M canis. Wood's lamp examinations had a sensitivity of 66.8% (95% CI 60.2-73.4) and a specificity of 74.8% (95% CI 64.2-85.1) compared with dermatophyte test medium (DTM) culture. In 78.8% (95% CI 61-91) of littermate or household groups with mixed Wood's lamp results, all cats were DTM culture positive. Under consistent incubation conditions, 202/202 diagnostic DTM plates for M canis-infected cats showed recognizable colony growth before 7 days (median 4 days), and 19/19 fomite carrier cat cultures showed growth before 12 days (median 5 days).

CONCLUSIONS AND RELEVANCE

Applying the results of this study to shelter protocols could optimize diagnostic approaches and shorten the length of stay for shelter cats and kittens, resulting in streamlined shelter operations and improved feline welfare.

Epidemiological investigation and molecular typing of dermatophytosis caused by Microsporum canis in dogs and cats

The objective of the present study was investigate the prevalence of dermatophytes in dogs, cats and environment floor through molecular epidemiology tools to identify the genetic profile of these infectious agents. This was an observational study with cross-sectional surveys design. Sample were collected from the hair and skin of 52 dogs and cats with the clinical suspicion of dermatophytosis, over a period of one year in Maringá, in the state of Paraná, Brazil. Household samples (carpets and floor), were collected from animals that were positive for dermatophytosis by morphological colonies characteristics, and samples of dogs or cats living in the same household as with the positive animals were also collected. After mycological confirmation, molecular typing was performed by random amplified polymorphic DNA (RAPD). Microsporum canis was the unic dermatophyto isolated whose prevalence was 26.9% (14/52) in animals with the clinical suspicion of dermatophytosis and four other animals that lived with positive animals. As some animals had more than one lesion site, there were 22 total positive cultures from samples from animals and another ten from abiotic sources. The majority of the animals that provided positive cultures for M. canis were aged up to five months (77.8%) and were female (66.7%). Molecular typing using the P1 primer revealed genetically distinct profiles in the symptomatic, asymptomatic and environmental animal samples, or the same animal, furthermore, showed that M. canis could have microevolution.

Dermatophytes and dermatophytosis in the eastern and southern parts of Africa

Dermatophytosis is currently a disease of global importance and a public health burden. It is caused by dermatophytes, which attack and grow on dead animal keratin. Dermatophytes belong to three genera, namely, Epidermophyton, Microsporum, and Trichophyton. The predominant clinical forms and causative agents vary from one region of the world to another. Poor socioeconomic status, high population densities, and poor sanitary conditions are some of the factors responsible for the high prevalence of dermatophytosis in many developing countries, which include countries in southern and eastern Africa, the focus of this review. To the best of our knowledge, there is currently no review article on published findings on dermatophytosis in the eastern and southern parts of Africa. This information will be of interest to the medical and research community since the world has become a global village. This review covers published research findings in eastern and southern regions of Africa until this date. The countries covered in the current review include Kenya, Ethiopia, Tanzania, South Africa, Mozambique, Madagascar, Malawi, Rwanda, Burundi, Uganda, Zambia, Zimbabwe, and Botswana. T. violaceum is the most common human etiological agent in all the countries under review with prevalence ranging from 56.7% to 95%, except for Madagascar (M. langeronii, reclassified as M. audouinii), Uganda (M. gypseum) and Malawi (M. audouinii). Tinea capitis was the most clinical type, followed by tinea corporis. Etiological agents of animal dermatophytoses were variable in the countries where they were reported. Major risk factors for dermatophytoses are age, climatic, and socioeconomic factors.

Development of enzyme immunoassays (ELISA and Western blot) for the serological diagnosis of dermatophytosis in symptomatic and asymptomatic cats

Dermatophytosis is the most common fungal infection in cats worldwide and plays an important role in both animal and human health due to their high zoonotic potential. Effective screening is a strong preventive measure and the fungal culture is quite useful but requires full laboratorial experience and it takes a long time to obtain the result. A rapid and accurate screening test for dermatophytosis in cats is crucial for the effective control of disease outbreaks. The aim of this study was to develop and evaluate the diagnostic efficacy of enzyme immunoassays (ELISA and Western blot [WB]) for the rapid and precise diagnosis of dermatophytosis in cats. Seventy cats of various ages were divided into three groups: S (symptomatic, n = 20), AS (asymptomatic, n = 30), and N (negative, n = 20). All animals were submitted to fungal culture and blood samples for carrying out the serological tests. A significant difference (P < 0.05) was found between IgG-specific levels of sera of Microsporum canis positive and negative animals. There was no statistic difference between groups symptomatic and asymptomatic. The ELISA test showed sensitivity of 94% and specificity of 75%. Receiver operating characteristic (ROC) analysis also showed higher diagnostic accuracy (AUC 0.925). The WB technique detected 13 bands, and the 50 kDa protein was considered the most immunogenic protein, observing reactivity in 83.3% in the symptomatic group and 66.6% in the asymptomatic group. The study concluded that ELISA and WB were useful tools to reliably detect cats that have been exposed to M. canis.

Assessment of real-time PCR cycle threshold values in Microsporum canis culture-positive and culture-negative cats in an animal shelter: a field study

Objectives Real-time PCR provides quantitative information, recorded as the cycle threshold (Ct) value, about the number of organisms detected in a diagnostic sample. The Ct value correlates with the number of copies of the target organism in an inversely proportional and exponential relationship. The aim of the study was to determine whether Ct values could be used to distinguish between culture-positive and culture-negative samples. Methods This was a retrospective analysis of Ct values from dermatophyte PCR results in cats with suspicious skin lesions or suspected exposure to dermatophytosis. Results One hundred and thirty-two samples were included. Using culture as the gold standard, 28 were true positives, 12 were false positives and 92 were true negatives. The area under the curve for the pretreatment time point was 96.8% (95% confidence interval [CI] 94.2-99.5) compared with 74.3% (95% CI 52.6-96.0) for pooled data during treatment. Before treatment, a Ct cut-off of <35.7 (approximate DNA count 300) provided a sensitivity of 92.3% and specificity of 95.2%. There was no reliable cut-off Ct value between culture-positive and culture-negative samples during treatment. Ct values prior to treatment differed significantly between the true-positive and false-positive groups ( P = 0.0056). There was a significant difference between the pretreatment and first and second negative culture time points ( P = 0.0002 and P <0.0001, respectively). However, there was substantial overlap between Ct values for true positives and true negatives, and for pre- and intra-treatment time points. Conclusions and relevance Ct values had limited usefulness for distinguishing between culture-positive and culture-negative cases when field study samples were analyzed. In addition, Ct values were less reliable than fungal culture for determining mycological cure.

Comparison of real-time PCR with fungal culture for the diagnosis of Microsporum canis dermatophytosis in shelter cats: a field study

Objectives Fungal culture requires at least 14 days for a final result, compared with 1-3 days for PCR. The study compared a commercial real-time dermatophyte PCR panel with fungal culture in cats in a shelter setting for: (1) diagnosis of Microsporum canis infection; and (2) determination of mycological cure. Methods This was a cross-sectional, observational study of cats with suspicious skin lesions or suspected exposure to dermatophytosis. Hair samples were collected for fungal culture and PCR prior to treatment and at weekly intervals until two negative culture results were obtained. Results One hundred and thirty-two cats were included, of which 28 (21.2%) were culture positive and 104 (78.8%) culture-negative for M canis. PCR correctly identified all culture-positive cats and 92/104 culture negative cats; there were 12 false-positive PCR results. The sensitivity and specificity of PCR were 100% (95% confidence interval [CI] 87.7-100) and 88.5% (95% CI 80.7-93.9), respectively. Data from 17 cats were available for assessment of mycological cure. At the time of the first and second negative fungal cultures, 14/17 (82.4%) and 11/17 (64.7%) tested PCR positive, respectively. Conclusions and relevance PCR showed high sensitivity and specificity for diagnosis of M canis dermatophytosis compared with fungal culture, but was unreliable for identifying mycological cure. False-positive results were relatively common. There were no false-negative PCR results and a negative PCR test was a reliable finding in this study. The ability to rapidly diagnose or rule out dermatophytosis could be a valuable tool to increase life-saving capacity in animal shelters.

Diagnosis and treatment of dermatophytosis in dogs and cats.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Dermatophytosis is a superficial fungal skin disease of cats and dogs. The most common pathogens of small animals belong to the genera Microsporum and Trichophyton. It is an important skin disease because it is contagious, infectious and can be transmitted to people.

OBJECTIVES

The objective of this document is to review the existing literature and provide consensus recommendations for veterinary clinicians and lay people on the diagnosis and treatment of dermatophytosis in cats and dogs.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

No one diagnostic test was identified as the gold standard. Successful treatment requires concurrent use of systemic oral antifungals and topical disinfection of the hair coat. Wood's lamp and direct examinations have good positive and negative predictability, systemic antifungal drugs have a wide margin of safety and physical cleaning is most important for decontamination of the exposed environments. Finally, serious complications of animal-human transmission are exceedingly rare.

Open-field study comparing an essential oil-based shampoo with miconazole/chlorhexidine for haircoat disinfection in cats with spontaneous microsporiasis

Objectives The goal of the present study was to compare the antifungal efficacy of an essential oil (EO) shampoo proven to be effective against Microsporum canis with miconazole/chlorhexidine for topical haircoat disinfection in cats treated concurrently with oral itraconazole. Methods Cats received treatment with oral itraconazole (Itrafungol) at a dose of 5 mg/kg/day pulse administration for 1 week, every 2 weeks for at least 6 weeks and were washed twice a week with a neutral shampoo with added EOs of Thymus serpyllum (2%), Origanum vulgare and Rosmarinus officinalis (5% each) for the period of systemic treatment. This protocol was compared with a conventional treatment (oral itraconazole + 2% miconazole/2% chlorhexidine shampoo). Results The treatment was well tolerated and adverse effects were not recorded. All cats were clinically negative at week 11. With respect to animals with extensive lesions, the speed of resolution was higher in cats with focal lesions. The animals showing diffuse lesions required more than a course of treatment to achieve a mycological cure. There was no significant difference between the number of weeks to obtain mycological cure for cats treated with EOs and animals treated conventionally. Conclusions and relevance The treatment appeared to be effective and well appreciated by the owners. The use of shampoo with the added EOs of T serpyllum, O vulgare and R officinalis would seem an interesting, natural alternative to conventional topical treatment.