Successful resolution of dermatophyte mycetoma following terbinafine treatment in two cats

Microsporum canis Causes Cutaneous and Extracutaneous Feline Dermatophytic Pseudomycetomas: Molecular Identification and Clinicopathological Characteristics

Dermatophytic pseudomycetoma (DPM) is a rarely reported invasive fungal infection of humans and animals, especially cats. This study aimed to identify dermatophytes, breed associations, and the frequency of extracutaneous (EC) involvement in feline DPM. Electronic records and formalin-fixed paraffin-embedded tissue (FFPET) from 32 suspected DPM cases in 30 cats were retrieved from a diagnostic laboratory between 2018 and 2024. To confirm DPM and molecular identity, DNA was extracted from FFPET for ITS2 sequencing, and immunohistochemistry was performed on PCR-negative cases. All cases were confirmed as DPM. Microsporum canis was the only dermatophyte identified. The sensitivity and specificity of ITS2 sequencing for M. canis identification in FFPET were 22/32 (68.8%) and 21/22 (95.5%), respectively. Exotic (36.7%) and Persian (23.3%) but not British breeds (26.3%) were over-represented compared to feline admissions at an affiliated veterinary hospital (8.5%, p < 0.001; 3%, p < 0.001; 21.6%, p = 0.817, respectively). Five cases (16.7%) had EC lesions; two had intra-abdominal masses; two had oral cavity masses, including one which extended into the cranial vault; and one had superficial cervical lymph node invasion. Exotic and Persian breeds are over-represented for DPM and M. canis is the primary cause. EC lesions of DPM may occur more commonly than previously thought.

Case report: Dermatophytic pseudomycetoma in a domestic Korean short hair cat treated with intralesional injection of amphotericin B and oral terbinafine administration

Dermatophytic pseudomycetoma (DPM), which is a deeper dermal and/or subcutaneous infection of dermatophytes, has been rarely reported in Domestic Korean Short Hair Cats. A 3-year-old, spayed female, domestic Korean Short Hair Cat presented with a history of crusts, nodules, and pruritus for 1 year. At the initial presentation, multifocal ulcerative nodules covered with yellowish grains were noted on her ventral thorax, abdomen, flank, and left hindlimb. Cytology of ulcerative nodules revealed degenerative neutrophils, macrophages, multinucleated giant cells, and hyphae. Histological examination of nodules revealed pyogranulomatous dermatitis with fungal plaques, and Microsporum canis and Staphylococcus aureus were identified in the culture. Therefore, the cat was diagnosed with DPM with secondary pyoderma. Oral itraconazole (10 mg/kg, once a day) was administered, but no significant improvement was observed. Therefore, intralesional (IL) injection of amphotericin B (0.6 mg/nodule) and oral administration of terbinafine (30 mg/kg, twice a day) were administered to the cat. With these medications, ulceration and the number and size of nodules decreased significantly, although large dome-shaped nodules remained. Skin lesions were treated with oral terbinafine and itraconazole administration for 5 months. However, after 6 months, recurrence of multifocal ulcerative nodules was observed, and the cat died 10 months after initial presentation. In this case, IL amphotericin B and oral terbinafine administration were partially effective in DPM treatment, suggesting that this may be an option for DPM treatment. Further studies to determine dose and frequency of IL amphotericin B in the management of DPM are warranted.

Invasive Fungal Infections and Oomycoses in Cats: 1. Diagnostic approach

CLINICAL RELEVANCE

In contrast to superficial fungal infections, such as dermatophytosis, invasive fungal infections (IFIs) are characterised by penetration of tissues by fungal elements. Disease can spread locally within a region or can disseminate haematogenously or via the lymphatics. The environment is the most common reservoir of infection. Since fungal spores are airborne, indoor cats are also susceptible to IFIs. Some environmental fungi are ubiquitous and present globally, while others are endemic or hyperendemic within specific geographic regions. Zoonotic pathogens include Microsporum canis, Sporothrix schenckii and Sporothrix brasiliensis.

AIM

In the first of a two-part article series, the approach to the investigation of feline IFIs and oomycoses is reviewed. As well as tips for diagnosis, and information on the ecological niche and distribution of fungal pathogens, the review covers clinical presentation of the most common IFIs, including cryptococcosis, histoplasmosis, blastomycosis, coccidioidomycosis, sporotrichosis, phaeohyphomycosis, aspergillosis and dermatophytic pseudomycetoma, as well as the oomycoses pythiosis, lagenidiosis and paralagenidiosis. In Part 2, the spectrum of activity, mechanisms of action, pharmacokinetic and pharmacodynamic properties and adverse effects of antifungal drugs are reviewed, and the treatment and prognosis for specific IFIs and oomycoses are discussed.

EVIDENCE BASE

The review draws on published evidence and the authors' combined expertise in feline medicine, mycology, dermatology, clinical pathology and anatomical pathology.

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.

Dermatophytic pseudomycetomas in two ferrets (Mustela putorius furo)

BACKGROUND

Dermatophytic pseudomycetoma is an atypical form of dermatophytosis where the infection is located in the deep dermal and subcutaneous tissues. Although rare, it is most commonly associated with Microsporum canis or Trichophyton sp. It has been reported in cats, dogs and horses.

OBJECTIVES

To describe the clinical and pathological findings of dermatophytic pseudomycetoma caused by M. canis and Trichophyton sp. in two domestic ferrets.

ANIMALS

Two pet ferrets (Mustela putorius furo).

METHOD AND MATERIALS

Case report.

RESULTS

Two ferrets were diagnosed with dermatophytic pseudomycetoma confirmed by histological examination of tissue and fungal culture. In both cases, ferrets presented with several cutaneous firm nodules 0.6-3 cm in diameter. Microscopic lesions revealed multifocal nodular pyogranulomatous inflammation with intralesional fungi.

CONCLUSIONS AND CLINICAL IMPORTANCE

To the best of the authors' knowledge, this is the first description of dermatophytic pseudomycetoma in domestic ferrets. This disease should be included in the differential diagnosis of nodular dermatopathies in this species.

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.

Treatment of refractory sino-nasal aspergillosis with posaconazole and terbinafine in 10 dogs

OBJECTIVES

To determine the safety and efficacy of posaconazole and terbinafine for the treatment of naturally occurring sino-nasal aspergillosis in dogs refractory to conventional topical and systemic treatment.

MATERIALS AND METHODS

Ten client-owned dogs with sino-nasal aspergillosis and not responsive to conventional treatments were prospectively enrolled to receive a dose of 5 mg/kg posaconazole orally every 12 hours for six months. All dogs were concurrently treated with doses of 30 mg/kg terbinafine orally every 12 hours and 5 mg/kg doxycycline orally every 12 hours for 6 to 18 months.

RESULTS

All 10 enrolled dogs completed the study. The treatment response was defined as complete clinical remission (n=7) or partial clinical remission (n=3). Two dogs relapsed after cessation of combination therapy. All dogs lived more than one year after starting combination therapy and eight dogs are alive at the time of writing. No clinically relevant adverse reactions or increases in hepatic enzyme activity occurred during the combination therapy.

CLINICAL SIGNIFICANCE

The results of this study suggest that this combination therapy appears safe and well-tolerated for the treatment of refractory sino-nasal aspergillosis in dogs. Long-term survival is possible with prolonged treatment, but relapse is possible. Larger prospective studies are warranted to further evaluate these preliminary findings.

Cutaneous blastomycosis and dermatophytic pseudomycetoma in a Persian cat from Bangkok, Thailand

This is a case report of concurrent of blastomycosis and pseudomycetoma in a 3 year-old Persian cat from Bangkok, Thailand. Histopathology from antemortem and postmortem samples revealed blastomycosis and dermatophyte pseudomycetoma. The PCR analysis of the formalin-embedded tissue of antemortem sample confirmed that blastomycosis was caused by Blastomyces dermatitidis. Dermatophyte infection was caused by Microsporum canis. According to the author's knowledge, this is the first case of Blastomyces dermatitidis and dermatophyte pseudomycetoma in South-East Asia.

Dermatophytosis in cats: ABCD guidelines on prevention and management

OVERVIEW

Dermatophytosis, usually caused by Microsporum canis, is the most common fungal infection in cats worldwide, and one of the most important infectious skin diseases in this species. Many adult cats are asymptomatic carriers. Severe clinical signs are seen mostly in kittens or immunosuppressed adults. Poor hygiene is a predisposing factor, and the disease may be endemic in shelters or catteries. Humans may be easily infected and develop a similar skin disease.

INFECTION

Infectious arthrospores produced by dermatophytes may survive in the environment for about a year. They are transmitted through contact with sick cats or healthy carriers, but also on dust particles, brushes, clothes and other fomites.

DISEASE SIGNS

Circular alopecia, desquamation and sometimes an erythematous margin around central healing ('ringworm') are typical. In many cats this is a self-limiting disease with hair loss and scaling only. In immunosuppressed animals, the outcome may be a multifocal or generalised skin disease.

DIAGNOSIS

Wood's lamp examination and microscopic detection of arthrospores on hairs are simple methods to confirm M canis infection, but their sensitivity is relatively low. The gold standard for detection is culture on Sabouraud agar of hairs and scales collected from new lesions.

DISEASE MANAGEMENT

In shelters and catteries eradication is difficult. Essential is a combination of systemic and topical treatments, maintained for several weeks. For systemic therapy itraconazole is the drug of choice, terbinafine an alternative. Recommended topical treatment is repeated body rinse with an enilconazole solution or miconazole with or without chlorhexidine. In catteries/shelters medication must be accompanied by intensive decontamination of the environment.

VACCINATION

Few efficacy studies on anti-M canis vaccines (prophylactic or therapeutic) for cats have been published, and a safe and efficient vaccine is not available.

A clinical report of entangled neonates' umbilical cord with queen's fur in Persian cat

A 3-year-old Persian queen was referred to Teaching Veterinary Hospital while 3 neonates' umbilical cords were entangled with the queen's tail hair. Close inspection of the cat showed that the umbilical cords of 3 kittens had twisted around together and entangled with the moms' hairs in the base of tail region. Also this complex has been warped around the left tarsus of one of the involved kittens and caused swelling and skin darkness in the involved limb. Operation was carried out urgently. After cutting the queen's involved hairs the kittens were released. Then the twisted umbilical cords and the hairs were isolated from the umbilical cord and the involved leg was released from the umbilical cords and the twisted umbilical cords were separated from each other. During one week follow up, dry gangrene occurred in the distal extremity of the injured limb and consequently, amputation was performed on the distal part of tibia. Our clinical findings suggest that long hair coats of queens could be a maternal life threatening factor for neonates' life.

Medical management of Trichophyton dermatophytosis using a novel treatment regimen in L'Hoest's monkeys (Cercopithecus lhoesti)

An outbreak of Trichophyton dermatophytosis was diagnosed in a group of four L'Hoest's monkeys (Cercopithecus lhoesti) housed in the primate section at a zoological collection. The affected animals presented with areas of non-pruritic alopecia, scaling and crusting. The diagnosis was based on culture and direct microscopy of hair plucks. Treatment was commenced with oral terbinafine at a dose of 8.25 mg/kg bodyweight, topical enilconazole washes and disinfectant fogging of the enclosure. Control measures were designed to limit the spread of infection and reduce the zoonotic risk. Treatment was successful, with no further clinical cases being diagnosed and with resolution of the clinical signs after four weeks and mycological cure after eight weeks.