Disseminated Mycoses in a Dog by Paecilomyces sp

J. Vet. Med. A 47, 243–249 (2000) © 2000 Blackwell Wissenschafts-Verlag, Berlin ISSN 0931–184X Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain Disseminated Mycoses in a Dog by Paecilomyces sp. M. E. GARCÍA1, J. CABALLERO1, P. TONI2, I. GARCIA2, E. MARTINEZ DE MERLO2, E. ROLLAN2, M. GONZALEZ2 and J. L. BLANCO1,3 Addresses of authors: 1Departamento Patologı́a Animal I (Sanidad Animal); 2Departamento Patologı́a Animal II, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain; 3 Corresponding author: Tel.: 91 3943717/91 3943719; Fax: 91 3943908; E-mail: [email protected] With 8 figures (Received for publication October 21, 1999) Summary We describe a case of canine mycoses initially diagnosed by clinical signs and enzyme-linked immunosorbent assay anti-fungal test, and later confirmed by the isolation of Paecilomyces sp. during the postmortem examination. The fungus was isolated from lesions in the kidneys, mitral valve, abdominal aorta and vertebral discs. In this kind of process, it is important to identify the responsible agent early in order to make a study of anti-fungal susceptibility and establish effective treatment. Introduction Canine systemic mycoses can be defined as those diseases produced by tissue invasion in one or more organs by a specific fungus. In the literature, the main responsible agent of this disease is considered to be Aspergillus terreus, but there are descriptions of other fungi, such as A. deflectus (Jang et al., 1986; Kahler et al., 1990), A. flavus (Southard, 1987) and A. flavipes (Day and Penhale, 1988), and even of other genera, such as Acremonium (Simpson et al., 1993), Penicillium (Wigney et al., 1990; Watt et al., 1995) and Chrysosporium (Watt et al., 1995). The clinical picture of these processes is very unspecific, especially in relation to the affected organs, making clinical diagnosis very difficult. The first signs are usually peripheral nervous signs, mainly lameness, spinal pain and lethargy. These are all consequences of the mould settling in the rachis. Case History A 5-year-old female crossed in German Shepherd weighing 23 kg, was admitted to the Internal Medicine Clinic in the Veterinary School of Madrid, with a 1-month history of depression, anorexia and weight loss. The owners explained that the dog declined movement and lay for long periods during the day. The previous year the dog had suffered an episode of fever, vomiting and weight loss, resolved with symptomatic treatment but, in the owners’ opinion, with no complete recovery. In addition, from the time the dog was 1 year old, it had suffered relapsing episodes of bilateral otitis resolved by antibiotherapy. Physical and neurological examination did not show significant disorders, except listlessness, slight spasticity in the walk and moderate cervical rigidity. Postural reactions, spinal reflexes and skull pairs examination were normal. A complete blood test was made (haematological, biochemical and serological). The only detected abnormalities were: slight leucocytosis (18 600/ml, reference values 6000–17 000/ml) U.S. Copyright Clearance Center Code Statement: 0931-184X/2000/4704-0243 $15.00/0 244 GARCÍA et al. with neutrophilia (14 880/ml, reference values 3000–11 500/ml), and a slight increase in the total plasma protein: (8 g/dl, reference values 5.5–7.5 g/dl). Analyses for the detection of antibodies against Leishmania and Ehrlichia were negative, and a urine analysis did not show abnormalities. An initial X-ray examination was made of the cervical and thoracic spine. At cervical level no abnormalities were detected, but in the latero-lateral view of the thorax, the presence of irregular bony growth was observed affecting most of the thoracic vertebral bodies; the study was extended to the lumbar area, showing similar lesions spreading to L7 (Fig. 1). This X-ray image is compatible with spondylitis, multiple discospondylitis and a primary or secondary vertebral neoplasic process. Multiple discospondylitis of unknown origin was diagnosed, and the dog was treated orally with a combination of lincomycin (400 mg/8 h), acetylsalicylic acid (250 mg/12 h) and Mysoprostol (100 mg/8 h). Simultaneously, a complete battery of tests revealed the origin and responsible agent of the suspected infection, resulting in the following: blood culture (negative result), urine culture (negative result), brucellosis test (negative result). However, in the aspergillosis enzyme-linked immunosorbent assay (ELISA) test a positive result was obtained. In view of these results, a presumptive diagnosis of systemic aspergillosis was established, and treatment was changed to oral ketoconazole (200 mg/8 h). Ten days after the beginning of this treatment, the dog showed a slight clinical improvement, with increased appetite and activity, and normal values in the analytical disorders. Radiological examination did not show significant changes. After 1 month, clinical improvement was complete, with normal liver function, but a positive value was still observed in the ELISA antiAspergillus. After another month, vomiting led to the removal of treatment for 1 week, after which the oral administration of ketoconazole was reintroduced. At this time, no X-ray changes were observed and the ELISA anti-Aspergillus remained positive. At the owners’ request, this was the dog’s last clinical control. The dog died suddenly 4 months later but enjoyed a good quality of life up to this time. The post-mortem showed a severe modification in the vertebral bodies from T1 to L7, with the intervertebral spaces collapsed and deformed; on cutting, the intervertebral discs showed small cavities, friable consistency and grey-brown colour (Fig. 2). No extension of the lesions to the medullary cavity was detected. Both kidneys showed an irregular capsular surface, with multiple white-yellowish nodules 0.5–1.5 cm in diameter appearing in the cortex, medulla and renal pelvis (Fig. 3). A friable and yellow nodule, 0.5 cm in diameter, was observed in the mitral valve adhered to the endothelium (Fig. 4). The abdominal aorta showed a thickened wall, with irregularities in the endothelium and mixed thrombi adhered to its surface (Fig. 5). Microscopically, the intervertebral spaces from T1–T2 to L6–L7 showed different ranges of discospondylitis. In the pulp nucleus, wide multifocal areas of necrosis were observed with slight mononuclear inflammatory infiltrates and multiple granulomatous formations around branching fungal hyphae (Fig. 6). Some of the intervertebral discs showed degeneration in the fibrous ring and osteomyelitis in the articular end of the vertebral bodies. There were no Fig. 1. X-ray latero-lateral observation in the thoracic region; discospondylitis. Disseminated Paecilomyces Mycosis in a Dog 245 Fig. 2. Intervertebral discs with small cavities and grey-brown colour. Fig. 3. Kidney with nodular lesion. Fig. 4. Mitral valve with friable and yellow nodule. microscopic lesions in the epidural space, meninx, or spinal medulla. The kidney parenchyma showed severe disorders, with the presence of necrotic areas with infarcts and cortex bleedings, multifocal interstitial mononuclear inflammatory infiltrates and severe sclerosis. Wide irregular 246 GARCÍA et al. Fig. 5. Abdominal aorta with irregularities in the endothelium and mixed thrombi adhered to its surface. Fig. 6. Intervertebral discs: multifocal areas of necrosis with slight mononuclear inflammatory infiltrates and branching fungal hyphae (haematoxylin and eosin stain, ×400). Fig. 7. Kidney; irregular foci of necrosis with polymorphonuclear inflammatory infiltrates, macrophages and abundant branching fungal hyphae (haematoxylin and eosin stain, ×200). foci of necrosis appeared in the medulla and renal pelvis with polymorphonuclear inflammatory infiltrates, macrophages and abundant branching fungal hyphae (Fig. 7). The nodule observed in the mitral valve was an eosinophilic and acellular formation, almost completely constituted Disseminated Paecilomyces Mycosis in a Dog 247 by foci of branching fungal hyphae, red corpuscles and fibrin (Fig. 8). An organized series of mixed thrombi was observed in the abdominal aorta with wide foci of bleeding, infiltration of neutrophils and hyalinized areas. A microbiological test was carried out. The same fungus was isolated from the lesions in the kidneys, aorta, intervertebral discs and endocardium, and was later identified as Paecilomyces sp. Discussion In the case we report, the first sign of mycosis was discospondylitis. The literature describes discospondylitis as a common lesion in this kind of disease (Pastor et al., 1993; Berry and Leisewitz, 1996; Perez et al., 1996). It is usually associated with other systemic disorders. Butterworth et al. (1995) reported a single case of unifocal discospondylitis mycoses without systemic involvement, in coincidence with only one other case (Weitkamp, 1982), whereas they referred to discospondylitis in association with disseminated aspergillosis in 17 cases. The evolution of canine systemic mycoses is usually the death of the animal, by natural causes or euthanasia. In the present description, diagnosis was confirmed by an anti-Aspergillus ELISA, following the method described in our laboratory (Blanco et al., 1997). We used a crude extract of Aspergillus fumigatus as an antigen to coat the plates. This indicates that crossed reactions with other fungal species can be expected (data not published). It is difficult to identify the fungus which causes the lesions; only a joint microbiological and histopathological diagnosis can identify the responsible agent with any certainty. In this sense, we cannot even depend on immunohistochemical techniques because of the cross reactions between the different fungal species. Therefore, we prefer the denomination ‘systemic mycoses’ and not the traditional and more specific ‘canine aspergillosis’ (Garcia et al., 1997). In this sense, Watt et al. (1995) reported systemic mycoses in 10 dogs, and it is curious that they describe the isolation of different fungal species, but with the term ‘canine aspergillosis’ used to refer to these processes. In our case, this was corroborated by the isolation of Paecilomyces sp., a saprophytic, ubiquitous organism and common airborne contaminant, previously described as a sporadic originating systemic process in dogs (Jang et al., 1971; Patnaik et al., 1972; Van Den Hoven and McKenzie, 1974; Patterson et al., 1983; Littman and Goldschmidt, 1987). An interesting aspect of these diseases is the question of the location of the primary lesions. In man, local infection attributable to contamination of a wound with Paecilomyces sp. should not develop into disseminated disease if the cell-mediated immunological system is intact. However, an apparent predisposing immunosuppressive disease was not found in the cases of canine systemic Paecilomyces reported (Littman and Goldschmidt, 1987). These authors Fig. 8. Nodule in mitral valve; eosinophilic and acellular formation, almost completely constituted by foci of branching fungal hyphae (haematoxylin and eosin stain, ×400). 248 GARCÍA et al. speculated that the dog acquired the infection from decaying organic material while swimming in pond water. The organism may have entered a penetrating wound in the inguinal area. We think that the most probable portal of entry of the fungus are wounds in skin and mucosa. From here, fungus can spread to different locations, mainly the rachis, where the disease can develop slowly. Patterson et al. (1983) reported that the initial site was the external ear, leading to otitis and dissemination to the middle and inner ear, and later to the brain, liver, spleen and abdominal lymph nodes. After several years, clinical disease was detected, and the dog euthanased. In the case described here, we would stress that when the animal was 1 year old it suffered from periods of otitis externa and media which were finally resolved by antibiotic therapy. Other opportunistic moulds may have a similar clinical picture and evolution. In our case, we tried treatment with ketoconazole, which was ineffective. However, we have to bear in mind that when the dog was diagnosed, the fungal infection was already widely disseminated in the organism, giving a situation which was almost certainly irreversible. This increases the importance of an effective methodology and early diagnosis of the disease, at a stage where treatment of the disease would be possible. This same treatment was tried by Littman and Goldschmidt (1987) with our same final result. They consider the Paecilomyces strain to be intermediate in its sensitivity to ketoconazole. It may be that the choice of therapy is the guiding factor in microbiological diagnosis. This allows us to identify the responsible agent and to make a study of antifungal susceptibility in order to establish effective treatment. In this sense, we recommend the Berry and Leisewitz (1996) treatment: surgical curettage of disc material from which the fungus could be cultured and observation of the hyphae by histopathology. Anti-fungal susceptibility testing would then allow us to establish the treatment. In this sense, we cannot ignore the increasing problem of the appearance of anti-fungal resistance in different isolates, a question described by us in yeasts isolated from chronic canine otitis (Guedeja-Marron et al., 1997). Acknowledgements We are grateful to the owner of Rain (the dog whose condition we describe) who collaborated with us at all times, especially after the death of the animal, in our search for an accurate diagnosis.We are grateful to Dr Jose A. Vázquez-Boland for his assistance with the photographic composition. References Berry, W. L., and A. L. 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