Subcutaneous and Deep Mycoses

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Questions and Answers

What is a characteristic of subcutaneous/deep mycoses?

They are very common in horses

They involve subcutaneous tissues in addition to dermal/epidermal involvement (correct)

They are easily diagnosed and treated

They are not chronic and progressive

What is the site of infection for Trichophyton spp.?

Areas of deep skin trauma

Hair follicles

Areas of superficial skin trauma (correct)

Muscle tissues

What is a common site of infection for Trichophyton spp.?

Abrasions of rider's boots and girths (correct)

Muscle tissues

Abrasions of rider's boots

Areas of superficial skin trauma

What is the primary method of diagnosis for Trichophyton spp.?

Clinical signs Signup and view all the answers

What is a treatment method for Trichophyton spp.?

Topical antifungal washes Signup and view all the answers

What is a method of control for Trichophyton spp.?

Early recognition and isolation of infected horses Signup and view all the answers

What is a characteristic of Microsporosis?

It is less common than Trichophyton spp. infections Signup and view all the answers

What is a common species of Microsporosis?

All of the above Signup and view all the answers

What is the primary mode of infection for Coccidioidomycosis?

Inhalation of fungal spores Signup and view all the answers

What is the mode of survival of Microsporum gypseum in beddings and other materials?

By forming spores and active mycelia that can survive for months Signup and view all the answers

What is the most common cause of Candidiasis in animals?

Species of the yeast-like fungus, Candida albicans Signup and view all the answers

What is the prognosis for horses with nerve damage from Candidiasis?

Horses may survive but not recover completely Signup and view all the answers

What is the primary location of infection in Aspergillosis in horses?

Guttural pouch Signup and view all the answers

What is the treatment for oral or skin candidiasis in horses?

Topical application or ointment Signup and view all the answers

What is the purpose of clipping off hair around defined lesions in the treatment of Microsporum gypseum infection?

To facilitate the application of topical fungicides Signup and view all the answers

What is the primary geographical location for Coccidioidomycosis infections?

Dry, desert-like regions of the southwestern United States and similar areas Signup and view all the answers

What is the characteristic of the early lesions of Microsporum gypseum infection?

Mild pruritus and exudation Signup and view all the answers

What is the significance of sunshine in the treatment of Microsporum gypseum infection?

It is a strong inhibitor of Microsporum spp. Signup and view all the answers

What is the common sign of Coccidioidomycosis in horses?

Loss of weight, coughing, fever, musculoskeletal pain, and abscesses of the skin Signup and view all the answers

What is the cause of arthritis in horses according to the text?

Candida fumata Signup and view all the answers

What is the typical duration of spontaneous resolution of Microsporum gypseum infection?

6-12 weeks Signup and view all the answers

What is the common presenting sign of Aspergillosis in horses?

All of the above Signup and view all the answers

What is the context in which epidemics of Coccidioidomycosis may occur?

When rainy periods are followed by drought Signup and view all the answers

What is the purpose of environmental disinfection in the treatment of Microsporum gypseum infection?

To prevent the spread of infection to other horses Signup and view all the answers

What is the usual duration of antifungal treatment for rhinosporidiosis?

6-12 months Signup and view all the answers

Which of the following is a characteristic of rhinosporidiosis?

Chronic infection of nasal passages and skin Signup and view all the answers

What is the primary mode of transmission of Sporothrix schenckii?

Through contaminated soil or plants Signup and view all the answers

What is a common symptom of rhinosporidiosis?

Nasal discharge and sneezing Signup and view all the answers

What is the standard treatment for rhinosporidiosis?

Surgical removal of lesions Signup and view all the answers

Which of the following is a characteristic of sporotrichosis?

Sporadic and chronic Signup and view all the answers

What is a common site of infection for Sporothrix schenckii?

Skin Signup and view all the answers

What is a possible complication of chronic sporotrichosis?

Fever and listlessness Signup and view all the answers

What is the typical location of nodule development in epizootic lymphangitis?

Under the skin Signup and view all the answers

What is the characteristic of the yeast forms in epizootic lymphangitis?

They have a distinctive appearance Signup and view all the answers

What is the primary method of preventing the spread of epizootic lymphangitis?

Strict hygienic precautions Signup and view all the answers

What is the common environment where Pythium insidiosum can persist?

In the environment for many months Signup and view all the answers

What is the characteristic of the lesions in pythiosis?

They are usually on the lower legs, abdomen, and chest Signup and view all the answers

What is the primary cause of pythiosis?

A water mold Signup and view all the answers

What is the common behavior of horses affected by pythiosis?

They mutilate the wounds if not closely monitored Signup and view all the answers

What is the usual restriction of infections in horses with pythiosis?

To the skin and the tissues just inside the skin Signup and view all the answers

Study Notes

Subcutaneous/Deep Mycoses

Involve subcutaneous tissues in addition to dermal/epidermal involvement
Can be localized or spread insidiously to contiguous tissues and via lymphatic vessels
Difficult to diagnose and treat, with seroconversion leading to chronic and progressive disease
More serious but geographically restricted, and rare or very rare in horses

Trichophytosis

Caused by Trichophyton spp.
Very common cutaneous mycosis worldwide
Spores highly resistant, leading to repeated infections in stables/yards
Requires epidermal damage to gain entry and remain in follicles of hair shafts
Site of infection typically areas of superficial skin trauma (tack and harness contact points)

Clinical Signs of Trichophytosis

Early signs: erect hairs, local swelling/edema, and mild exudate
Advanced signs: complete shedding of hairs, lesions easily and completely epilated, leaving silvery exposed epidermis
Common sites of infection: abrasions of rider's boots and girths

Diagnosis and Treatment of Trichophytosis

Diagnosis: clinical signs, differential diagnosis with other fungal diseases, and biopsy
Treatment: isolation of infected horse, hygiene and sanitation, topical antifungal washes, oral griseofulvin (not for pregnant mares), and use of fungicidal disinfectants

Control of Trichophytosis

Vaccination in some countries
Early recognition and isolation of infected horses
Stable and personal hygiene
Individualized tack, harness, and rugs
Use of gloves

Microsporosis

Caused by Microsporum spp.
Less common than Trichophyton spp. infections
Isolated lesions more common than extensive coalescing areas
Pathogenesis same as trichophytosis
Common species: M. equinum, M. canis, M. gypseum

Clinical Signs of Microsporosis

Early signs: small expanding areas of localized edema resembling urticaria
Advanced signs: early lesions with exudate and mildly pruritic, horse rubs affected areas but does not bite
Plucking of hairs resented because not all hairs are affected

Diagnosis and Treatment of Microsporosis

Diagnosis: clinical signs, cultures and microscopy of stained smears and hairs, and secondary urticarial-like plaques
Treatment: local topical washes with fungicide, environmental disinfection, and sunshine (strong inhibitor of Microsporum spp.)
Prognosis: excellent, most resolved spontaneously within 6-12 weeks

Aspergillosis (Guttural Pouch Mycosis)

Fungal infection caused by Aspergillus species
Primarily a respiratory infection that may become generalized
Found worldwide in almost all domestic animals and many wild animals
Susceptibility to fungal infections varies among species
Most common form in horses: fungal disease affecting the guttural pouch

Clinical Signs of Aspergillosis

Nosebleed and difficulty in breathing or swallowing
Holding the head extended or low, head-shaking, swelling of the head, neurologic signs, and nasal discharge

Treatment of Aspergillosis

Topical and oral antifungal agents
Outlook: guarded, horses may survive but not recover completely, particularly if nerves are damaged

Candidiasis

Localized fungal disease affecting mucous membranes and skin
Caused by Candida albicans
Distributed worldwide in various animals
Most commonly seen in foals
Signs: variable and nonspecific, may be associated with primary or predisposing conditions

Treatment of Candidiasis

Ointment or topical application
Different drugs given by mouth or through the vein to resolve arthritis or treat generalized candidiasis

Coccidioidomycosis (Valley Fever)

Dustborne, noncontagious infection caused by Coccidioides immitis
Limited to dry, desert-like regions of the southwestern United States and similar areas of Mexico and Central and South America
Inhalation of fungal spores is the only established mode of infection
Epidemics may occur when rainy periods are followed by drought, resulting in dust storms

Clinical Signs of Coccidioidomycosis

Loss of weight, coughing, fever, musculoskeletal pain, and abscesses of the skin
Nodules develop under the skin, increasing in size and undergoing cycles of granulation and partial healing

Diagnosis and Treatment of Coccidioidomycosis

Diagnosis: microscopic examination of discharges from infected area or biopsy specimens
Treatment: surgical removal of lesions combined with antifungal drugs, but no completely satisfactory treatment is known
Strict hygienic precautions are essential to prevent spread

Pythiosis

Disease caused by Pythium insidiosum, a water mold
Occurs in tropical and subtropical areas of the world, seen in warmer sections of the US
Infections in horses are most commonly restricted to the skin and tissues just inside the skin
Large, circular nodules or areas of swelling can become open, draining sores

Treatment of Pythiosis

Antifungal drugs may be considered in cases when surgery is not possible
Antifungal treatment is long-term (6-12 months), expensive, and has variable results

Rhinosporidiosis

Chronic infection, primarily of the lining of the nasal passages and occasionally of the skin
Caused by Rhinosporidium seeberi
Rarely fatal, and uncommon in North America
Seen most often in India, Africa, and South America

Clinical Signs of Rhinosporidiosis

Nasal discharge and sneezing
Infection of the nasal mucosa is characterized by polyp-like growths
Skin lesions may be single or multiple, attached at a base or have a stem-like connection

Treatment of Rhinosporidiosis

Surgical removal of lesions is considered the standard treatment, but recurrence is common

Sporotrichosis

Sporadic chronic disease caused by Sporothrix schenckii
Organism is found around the world in soil, vegetation, and timber
Infection usually results when the organism enters the body through skin wounds
Transmission of the disease from animals to humans can occur

Clinical Signs of Sporotrichosis

Small, firm nodules develop at the site where infection enters the body
Although generalized illness is not seen initially, chronic illness may result in fever, listlessness, and depression

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Description

This quiz covers subcutaneous and deep mycoses, including characteristics, diagnosis, and treatment. It also touches on Trichophytosis, a common cutaneous mycosis caused by Trichophyton spp.