Dermatophytosis in a Hyacinth Macaw (Anodorhynchus hyacinthinus) - A Case Report

Antonio Ramis, Jesus Fernandez-Moran, Xavier Gibert, and Hugo Fernandez-Bellon

Department of Pathology, School of Veterinary Medicine, Universitat Autonoma de Barcelona, 08193-Bellaterra, Barcelona (SPAIN) (Ramis, Gibert, Fernandez-Bellon) and Parc Zoologic de Barcelona, Parc de la Ciutadella s/n, Barcelona (SPAIN) (Fernandez-Moran)

Abstract. A dermatophyte infection in a Hyacinth Macaw (Anodorhynchus hyacinthinus) is described. The cutaneous lesions were observed in the dorsocaudal aspect of the head. Treatment with ketoconazole was unsuccessful. The disease progressed causing osteomyelitis and lysis of the temporal bone. The bird ultimately was euthanatized and a necropsy was performed. Gross necropsy lesions included extensive osteomalacia associated with lysis of the temporal bone. Microscopic lesions are described and the possible pathogenesis of the process is discussed.

Key words: Hyacinth macaw, Anodorhynchus hyacinthinus, Dermatophytosis, Trichophyton mentagrophytes, Osteolysis, Osteomyelitis

Introduction

The superficial mycoses are fungal infections that involve superficial layers of the skin, hair, and claws. The organisms may be dermatophytes such as Microsporum sp. and Trichophyton sp. which are able to use keratin; however, other fungi such as Candida sp. and Malassezia sp. may also produce superficial mycoses. ¹ Trichophyton spp. have been associated with scaly, crusty lesions of the wattle, comb, and legs in gallinaceous birds. These fungi also have been documented as causes of dermatologic problems in ducks, pigeons and canaries. ^2,3 Lastly, Trichophyton spp. and Microsporum gypseum have been reported as causes of dermatitis in Canaries and Budgerigars respectively. ⁴ Clinical evidence of superficial mycosis includes alopecia (especially of the head and the neck), scaliness, and formation of concentric, ring-shaped skin lesions. ⁵ Clinical signs in caged birds include pruritus, automutilation, and feather plucking. ⁵ Lesions are limited to the skin and feather follicles with minimal tissue reaction. ⁵ In fact, dermatophytes seem unable to invade organs other than the keratinized layers of skin, hair, and nails. ⁶ Treatment of avian superficial mycoses can be difficult. ⁵

Case Report

A 20-year-old, female, Hyacinth Macaw (Anodorhynchus hyacinthinus), kept in an outdoor cage shared with other macaw species, developed a broad, concentric ring-shaped, scabby lesion on the temporal area of the head. The lesion had been progressive over three months and was non-pruritic. The bird was isolated in a single cage and the crust of the lesion was removed. Hemorrhagic and necrotic foci, as well as granulation tissue, were observed in the underlying subcutaneous tissue (Fig.1). Swab samples were taken for microbiological studies and the resected tissue was fixed in 10% neutral-buffered formalin for histopathological studies. The wound was finally lavaged with an iodinated solution. ^a

Fig. 1. Hyacinth Macaw. Notice feather loss, hemorrhage, and cutaneous necrosis.

Fungal growth was detected in Sabouraud’s agar. The macroscopic and microscopic characteristics of the colonies were typical of Trichophyton mentagrophytes. Histologically, the resected tissue consisted of fibrinoid debris and detritus, but numerous hyphae were observed. The hyphae were surrounded by an inflammatory infiltrate composed of macrophages and multinucleated giant cells. The fungal formations, apparently segmented hyphae, were better observed with periodic acid-Schiff (PAS) and Grocott staining (Fig.2).

Fig. 2. Hyacinth Macaw, Skin, Grocott stain. Numerous fungal hyphae stain black.

A dermatophytosis caused by T. mentagrophytes was diagnosed. Treatment with ketoconazole^b (25 mg/Kg PO BID x 30 days) and lavage of the affected area with a iodinated solution^a was instituted. Since no response was observed, the antifungal treatment was prolonged for 30 more days. However, the cutaneous lesion worsened, exposing the underlying bone in some areas. The bird was finally euthanatized.

A complete necropsy was performed. The macroscopic lesions were confined to the cutaneous disease involving the back of the head. Both temporal bones showed marked reddish discoloration and two perforations of approximately 0.8 cm diameter (Fig. 3) were observed. Upon opening the skull, two granulomatous formations were observed that partially adhered to the temporal bones over the brain surface close to the osseous perforations. On the brain sections performed, focal areas of reddish-brown discoloration were observed in the cerebral cortex adjacent to the granulomatous formations. In addition, samples from all organs and tissues were taken and fixed in 10% neutral-buffered formalin for histopathological study.

Fig. 3. Hyacinth Macaw, Calvarium. Two oval perforations are present in the temporal bones.

Histologically, the more significant lesions were found in the temporal bones and the brain; the skin where the cutaneous lesion had been was not found. The cancellous bone showed severe congestion and abundant granulation tissue with perivascular inflammatory infiltrates of degranulated heterophils (Fig. 4). In addition, extensive osteolysis was observed with abundant osteoclasts adjacent to bony spicules in the vicinity of the perforated bone (Fig. 5). The macroscopic reddish-brown foci previously observed in the cerebral cortex corresponded to areas of hemorrhage and malacia without associated inflammatory infiltrates. Lastly, the granulomatous formations that adhered the brain surface to the temporal bones corresponded to remnants of partially destroyed osseous tissue, necrotic material, and bacterial colonies surrounded by histiocytic inflammatory infiltrates with multinucleated giant cells (Fig.6). Fungal organisms were not seen in osseous or nervous tissues. A granulomatous osteomyelitis with extensive osteolysis and focally extensive malacia in the underlying nervous tissue were diagnosed.

Fig. 4. Hyacinth Macaw, Temporal bone, H&E stain. Granulation tissue is apparent within the intratrabecular spaces.	Fig. 5. Hyacinth Macaw, Temporal bone, H&E stain. Osteoclasts line bony trabeculae near site of osteolysis.	Fig. 6. Hyacinth Macaw, Temporal bone, H&E stain. Necrosis of the temporal bone is associated with bacterial microcolonies (left center) and extensive heterophilic inflammation (lower right).

Discussion

The presence of cutaneous lesions and the isolation of T. mentagrophytes lead to the diagnosis of dermatophytosis. Despite being relatively frequent in gallinaceous birds,² dermatoses caused by Trichophyton spp. are extremely rare in psittacine birds. Only one case of dermatophytosis caused by M. gypseum in Budgerigars was found in the literature. ⁴ Since primary skin infections are rare,² a possible explanations for the pathogenesis of the process could be that the dermatophytosis was secondary to a traumatic wound, feather plucking by other birds from the shared cage, or to self-mutilation.

The appearance of the cutaneous lesion, its location, and the fact that it did not spread to other cutaneous areas are typical features of dermatophytoses in birds. ²However, the lack of pruritus and the severity of the cutaneous lesion that extended to the adjacent bone, causing lysis, and reaching the brain are unusual. Pruritus is usually described in avian cutaneous infections,⁵ but is usually minimal or absent in mammals. ¹ Since very few cases of dermatophytosis have been described in psittacine birds, pruritus could be an uncommon sign of dermatomycosis in these avian species. Because fungal organisms were not found in any of the osseous or brain lesions, the destruction within these tissues could be due to trauma such as self-mutilation. On the other hand, dermatophytes seem unable to invade organs other than skin, hair, and nails. ⁶

To conclude, to our knowledge this is the first report of dermatophytosis in a large psittacine bird.

Sources and Manufacturers

a. Betadine solution, Purdue Frederick Co. , Norwalk, CT
b. Nizoral, Janssen Pharmaceutical Inc. , Piscataway, NJ

Acknowledgments

We would like to thank P. Losada and B. Perez their assistance in histologic sectioning and staining.

References

1. Scott DW, Miller WH, Griffin GE (eds): Small Animal Dermatology. WB Saunders Company, Philadelphia, 1995, pp. 329-391.

2. Bauck L: Mycoses. In: Ritchie BW, Harrison GJ, Harrison LH (eds): Avian Medicine: Principles and Application. Wingers Publishing Inc. , Lake Worth, FL, 1994, pp. 997-1006.

3. Cooper JE, Harrison GJ: Dermatology. In: Ritchie BW, Harrison GJ, Harrison LH (eds): Avian Medicine: Principles and Application. Wingers Publishing Inc. , Lake Worth, FL, 1994, pp. 607-639.

4. Keymer IF: Micoses. In: Petrak ML (ed): Diseases of Cage and Aviary Birds. Lea and Febiger, Philadelphia, 1982, pp. 599-605.

5. Campbell TW: Mycotic Diseases. In: Harrison GJ, Harrison LH (eds): Clinical Avian Medicine and Surgery. WB Saunders Company, Philadelphia, 1986.

6. Murray PR, Kobayashi GS, Pfaller A, Rosenthal KS (eds): Medical Microbiology. Mosby Europe, London, 1994, pp. 404-415.

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