Diagnostic yield of cytologic analysis of pericardial effusion in dogs

A case report: Null-cell cardiac lymphoma in an English bulldog

This case report describes a novel example of an extranodal null-type lymphoma in the myocardium of a middle-aged English bulldog who presented with signs of right heart failure. An echocardiogram found, in addition to the pericardial effusion, thickened right and left ventricular free walls and the interventricular septum. The right ventricular free wall myocardium had multinodular lesions, suspicious for infiltrative disease. The owner elected humane euthanasia, and permission for necropsy was obtained. Multifocal left and right ventricular nodules and an incidental aortic root mass were detected, the latter of which was later confirmed as a chemodectoma. Microscopically, the myocardial nodules were sheets of round cells consistent with a high-grade lymphoma. Neoplastic cells were not immunoreactive to CD3 (T-cell) or CD20 and CD79a (B-cell), Mum-1 (plasma cell), CD117 (mast cell), or CD18 (histiocyte). These findings are consistent with a high-grade, null-cell-type lymphoma.

Presumed primary cardiac mast cell tumor, pericardial effusion, and arrhythmia in a dog

A 13-year-old female spayed border collie cross presented for pericardial effusion, arrhythmia, and a suspected cardiac mass. Echocardiogram revealed severe thickening and hypokinesis of the interventricular septum with a heterogenous, cavitated myocardium, concerning for neoplasia. Electrocardiogram revealed predominantly accelerated idioventricular rhythm with frequent periods of nonsustained ventricular tachycardia. Occasional prolonged PR intervals terminating in an aberrantly conducted QRS complex were present. These beats were postulated to represent either first-degree atrioventricular block with aberrant QRS conduction or atrioventricular dissociation. Cytology of the pericardial effusion revealed atypical, suspected neoplastic, mast cells. The patient was euthanized, and postmortem examination confirmed full-thickness infiltration of the interventricular septum by a mast cell tumor, with metastasis to the tracheobronchial lymph node and spleen. Given the anatomic location of the mass, the observed atrioventricular nodal conduction delay may represent neoplastic infiltration of the atrioventricular node. Neoplastic infiltration of the ventricle was suspected to cause the accelerated idioventricular rhythm and ventricular tachycardia. To the authors' knowledge, this is the first reported case of a primary cardiac mast cell tumor causing arrhythmia and pericardial effusion in a dog.

Diagnosis, Prognosis, and Treatment of Canine Hemangiosarcoma: A Review Based on a Consensus Organized by the Brazilian Association of Veterinary Oncology, ABROVET

Hemangiosarcoma is a mesenchymal neoplasm originating in the endothelial cells of blood vessels; they can be classified as non-visceral and visceral types. Non-visceral hemangiosarcomas can affect the skin, subcutaneous tissues, and muscle tissues; visceral hemangiosarcomas can affect the spleen, liver, heart, lungs, kidneys, oral cavity, bones, bladder, uterus, tongue, and retroperitoneum. Among domestic species, dogs are most affected by cutaneous HSA. Cutaneous HSA represents approximately 14% of all HSA diagnosed in this species and less than 5% of dermal tumors, according to North American studies. However, Brazilian epidemiological data demonstrate a higher prevalence, which may represent 27 to 80% of all canine HSAs and 13.9% of all skin neoplasms diagnosed in this species. Cutaneous HSA most commonly affects middle-aged to elderly dogs (between 8 and 15 years old), with no gender predisposition for either the actinic or non-actinic forms. The higher prevalence of cutaneous HSA in some canine breeds is related to lower protection from solar radiation, as low skin pigmentation and hair coverage lead to greater sun exposure. Actinic changes, such as solar dermatosis, are frequent in these patients, confirming the influence of solar radiation on the development of this neoplasm. There are multiple clinical manifestations of hemangiosarcoma in canines. The diagnostic approach and staging classification of cutaneous HSAs are similar between the different subtypes. The definitive diagnosis is obtained through histopathological analysis of incisional or excisional biopsies. Cytology can be used as a presurgical screening test; however, it has little diagnostic utility in cases of HSA because there is a high risk of blood contamination and sample hemodilution. Surgery is generally the treatment of choice for dogs with localized non-visceral HSA without evidence of metastatic disease. Recently, electrochemotherapy (ECT) has emerged as an alternative therapy for the local ablative treatment of different neoplastic types; the use of radiotherapy for the treatment of dogs with cutaneous HSA is uncommon. There is greater consensus in the literature regarding the indications for adjuvant chemotherapy in subcutaneous and muscular HSA; doxorubicin is the most frequently used antineoplastic agent for subcutaneous and muscular subtypes and can be administered alone or in combination with other drugs. Other therapies include antiangiogenic therapy, photodynamic therapy, the association of chemotherapy with the metronomic dose, targeted therapies, and natural products. The benefits of these therapies are presented and discussed. In general, the prognosis of splenic and cardiac HSA is unfavorable. As a challenging neoplasm, studies of new protocols and treatment modalities are necessary to control this aggressive disease.

Outcome of dogs treated with chemotherapy for mesothelioma: A retrospective clinical study on 40 cases and a literature review

Mesothelioma is an uncommon cancer in dogs for which there is no established standard of care. Chemotherapy is often suggested despite no definitive proof of efficacy. The aim of this study was to evaluate the impact of chemotherapy on survival of dogs with mesothelioma. A retrospective multicentric study was carried out. To be included, dogs needed to present an evocative clinical evolution and a morphological diagnosis of mesothelioma. Exclusion of other cause of effusion and complete clinical follow-up were also required. Fourty dogs were included, 27 received chemotherapy (group 1) and 13 did not (group 2). Groups were heterogeneous regarding the proportion of animals undergoing surgery as part of their treatment (16 in group 1, 2 in group 2; p = .016) and homogeneous otherwise. Univariate analysis showed that dogs from group 1 survived significantly longer than dogs from group 2 (MST: 366 vs. 74 days; p < .001). Complete resolution of effusion after the first chemotherapy administration positively correlated with survival in group 1 (MST: 415 vs. 160 days; p < .01). All other variable tested had no significant impact on survival in univariate analysis, but dogs undergoing surgery and dogs having serous membranes' modification at medical imaging tended to survive longer. Multivariate analysis confirmed that chemotherapy was the sole variable independently associated with survival in our study (odds ratio 5.57-6.12; p < .01).

Pericardial effusion in a dog due to T‐cell lymphoma of granular lymphocyte type

Pericardial effusions in dogs are most often diagnosed as haemorrhagic and idiopathic. Pericardial effusions secondary to an underlying neoplastic process are infrequently diagnosed, as neoplastic cells are rarely observed in a sample of the effusion. In the present report, we describe a 9‐year‐old dog with pericardial effusion due to T‐cell lymphoma of granular lymphocyte type. Immunophenotyping and molecular clonality PCR were performed to confirm the cytologic diagnosis. To our knowledge, this is the first report of pericardial effusion in a dog due to T‐cell lymphoma of granular lymphocyte type.

Comparison of effusion cell block and biopsy immunohistochemistry in mesothelial hyperplasia, mesothelioma, and carcinoma in dogs

BACKGROUND

Determining the cause of effusions is challenging and might require a biopsy. Whether cell blocks from effusions are representative of biopsies requires investigation. A previously developed immunohistochemical panel aids in the differentiation of hyperplastic and neoplastic mesothelium in canine biopsies but has not been investigated in effusions.

OBJECTIVES

The study aimed to assess cell blocks as an alternative to biopsies and determine whether immunohistochemistry helps distinguish hyperplastic mesothelium, mesothelioma, and carcinoma.

METHODS

Effusions and biopsies were collected from five dogs with mesothelial hyperplasia (group MH), six with mesothelioma (group M), and five with carcinoma (group C). Immunohistochemistry (IHC) for cytokeratin, vimentin, Wilm's tumor protein 1 (WT1), desmin, glucose transporter 1 (GLUT1), and insulin-like growth factor II mRNA-binding protein 3 (IMP3) was performed. Sections were scored for staining intensity and the percentage of positively stained cells.

RESULTS

In paired cell blocks and biopsies, vimentin and WT1 staining were positively correlated for intensity and the percentage of positive cells, although not all paired results were identical. The intensity of IMP3 staining in cell blocks was higher in group M than in group C (P = 0.012), and WT1 staining was higher in group MH than in group C (P = 0.020). For biopsies, the intensity of WT1 staining was higher in group MH than in group C (P = 0.031). In group C, WT1 was negative in all cell blocks and biopsies, and desmin was negative in four of five cases.

CONCLUSIONS

IHC results for the cell blocks and biopsies were comparable for potentially useful markers, such as WT1, which helped discriminate between groups. IHC provided additional information, although results were not always definitive. Further studies on a larger population are required.

Canine and feline haemangiosarcoma

INTRODUCTION

Haemangiosarcoma (HSA) is a malignant neoplasm of dogs and cats that is suspected to originate from a pluripotent bone marrow progenitor with a complex and multifactorial pathogenesis.

APPROACH

Pertinent literature was identified, reviewed, and summarized for inclusion in the manuscript.

RESULTS/INTERPRETATION

Dogs are more frequently diagnosed with HSA than cats, and primary sites of this disease include dermal, subcutaneous/intramuscular, and visceral (most commonly the spleen). Dogs and cats with HSA generally have a poor prognosis owing to the rapid and widespread metastasis typically associated with this disease. However, some forms such as cutaneous HSA behave in a less aggressive fashion with improved outcomes. Surgical excision and anthracycline-based chemotherapy remain the mainstays of treatment, although novel treatment modalities are currently under investigation for potential roles in treatment of this disease.

CONCLUSION

This review aims to describe the clinical presentation and progression of the various forms of HSA in dogs and cats as well as to provide a systematic review of the veterinary literature with a focus on the various published treatment options and associated outcomes.

Cell blocks in veterinary medicine: A comparison of two methods (cell tube and agar) in 52 effusions from dogs and cats

BACKGROUND

Cell blocks are alternative preparations of fluid cytological specimens. They can be used for immunochemical studies as complementary tools or when other techniques (eg, immunocytochemistry, flow cytometry) are not available.

OBJECTIVES

We aimed to provide comparative morphologic, immunohistochemical, and technical features of agar-based cell blocks (ACBs) and cell tube blocks (CTBs) from cavitary effusions.

METHODS

Agar-based cell blocks and CTBs were obtained from canine and feline effusions with neoplastic/atypical cells or with packed cell volumes ≥3%. Cellularity, RBC separation, and cellular features were evaluated on digitalized H&E slides with evaluators blinded to the method. The immunohistochemical intensity and nonspecific background were assessed on pan-cytokeratin and vimentin-stained slides. Overall yield was calculated, and morphologic and immunohistochemical features were compared among paired samples. Technical and cellular features were also described.

RESULTS

Agar-based cell blocks and CTBs yielded evaluable sections in 100% (52/52) and 98% (51/52) of the cases, respectively. Cellularity and RBC separation scores were significantly higher in CTBs. Similar staining intensities were observed, and background staining was more frequently seen in pan-cytokeratin-stained ACBs. Only basic materials and equipment were required for both methods. Agar-based cell block preparations were more operator dependent and difficult to standardize, whereas CTBs were easier to prepare, but laboratory processing was more demanding.

CONCLUSIONS

Both methods can be used to produce good sections for immunohistochemistry staining with no significant differences. Cell tube blocks are beneficial for RBC-rich samples, and little additional training is required to prepare the blocks. Both types of cell blocks are reliable, cost-effective methods that could be introduced in diagnostic laboratories to further characterize canine and feline effusions.

Obstructive right ventricular outflow tract myxosarcoma in an adult dog

An 8-year-old female spayed German Shepherd cross was presented for acute onset of respiratory distress. Four days before presentation, the owner noticed a reduced appetite and reluctance to move. Clinical examination identified muffled lung sounds and a left base, diamond-shaped systolic murmur graded 4/6. Echocardiography identified pleural and pericardial effusion, ascites and a myxoid mass (39 mm/18.9 mm) obstructing the right ventricular outflow tract and interfering with the pulmonary valve function. Given the poor prognosis, the dog was euthanatised, and a postmortem examination was performed. Grossly, a mass with a heterogeneous appearance was identified below the pulmonary valve leaflets. Based on histopathological and immunohistochemical findings, a diagnosis of intracardiac myxosarcoma affecting the subvalvular region of the pulmonary artery was made. To the author's knowledge, this is the first report of right ventricle out flow tract myxosarcoma in the canine species.

Review of oncological emergencies in small animal patients

Oncological emergencies can occur at any time during the course of a malignancy and need to be recognized promptly to maximize successful outcomes. Emergencies are characterized as chemotherapy-induced, paraneoplastic syndromes, or directly related to the neoplasm. Prompt identification with treatment of these emergencies can prolong survival and improve quality of life, even in the setting of terminal illness. This review aims to educate the reader on the pathophysiology, clinical presentation and treatment of some of these emergencies, and to review the current veterinary literature to help educate veterinarians in primary and tertiary facilities to know how to diagnose and treat these serious conditions.

Histiocytic Sarcoma and Hemangiosarcoma Update

Histiocytic sarcoma (HS) and hemangiosarcoma (HSA) are uncommon and aggressive neoplasms that develop much more frequently in dogs than in cats. Breed-specific predispositions have been identified for both cancers. The development of novel diagnostics is underway and may aid in earlier diagnosis. Therapeutic approaches to HS and HSA depend on the stage of disease and may include surgery, radiation therapy, and chemotherapy. Such interventions improve outcome; however, aside from a small number of clinical circumstances, both diseases are considered largely incurable. Continued efforts toward the identification of driver mutations and subsequent druggable targets may lead to improvements in long-term prognosis.

Canine cavitary effusion: a retrospective study of 304 cases in Brazil

ABSTRACT The objective of this study was to determine the frequency of different categories of specific and general classification in canine cavitary effusions (CE), as well as their association with the underlying etiologies. The laboratorial and clinical data from 304 cases of canine CE were retrospectively assessed. In 32.9% (100 cases), at least one of the specific classification categories was established, with a subtotal predominance of neoplasia (42%), bacterial serositis (24%) and hemorrhage (16%). Neoplasia was confirmed by effusion cytology in 57.5% of the cases with histopathological confirmation. From the cases in which the specific classification was not obtained, 35.8% were classified as modified transudate, 30.4% as pure transudate, 21.1% % as exudate and 12.7% was not included in any general category. The most common causes of effusion among these cases were hypoproteinemia and/or hipoalbuminemia (HPHA) (25.8%), hepatopathy (22.5%), cardiac insufficiency (15.5%) and cytologically undetected cases of neoplasia (12.4%). In conclusion, HPHA, hepatopathy and neoplasia represents important etiologies for canine CE development. Classification of effusions, solely based on [TP] and TNCC, might be an inaccurate diagnostic tool of effusions. New laboratorial classification methods for canine CE should be researched.

Pericardial Effusion in a Dog with Pericardial Hemangiosarcoma

An adult Jack Russel terrier dog presented for evaluation of large-volume peritoneal and pleural effusion. Echocardiography revealed scant pericardial effusion and abnormally thickened pericardium. Electrocardiography revealed complete atrioventricular block with junctional and ventricular escape beats and occasional ventricular premature complexes. Computed tomography of the thorax confirmed diffuse abnormal thickening of the pericardium, and a tentative diagnosis of constrictive-effusive pericarditis was made. The dog underwent subtotal pericardiectomy to remove the parietal pericardium and permanent epicardial pacemaker implantation to manage bradycardia. Based on pericardial histopathology and immunohistochemistry, a diagnosis of pericardial hemangiosarcoma was made. Systemic chemotherapy was initiated with doxorubicin 1 month after surgery. Despite initial improvement with chemotherapy, the dog was euthanized 4 months after surgery because of development of recurrent pleural effusion. To the author's knowledge, this is the first case report in dogs to describe isolated pericardial location of hemangiosarcoma resulting in constrictive-effusive pericarditis.

Canine leishmaniasis associated with pericardial effusion in a 4-year-old dog

A 4-year-old crossbreed dog presented with a two-day history of lethargy and abdominal effusion. Physical examination and echocardiography revealed pericardial effusion with cardiac tamponade. Pericardiocentesis was performed. Intracytoplasmic Leishmania amastigotes were found on cytological examination of the pericardial fluid. The animal was treated with N-methylglucamine antimoniate and allopurinol. After an initial favorable response, cardiac tamponade reoccurred one month later. The dog died during a pericardiectomy four months after the initial diagnosis. Histology confirmed the presence of chronic pericarditis. The presence of Leishmania amastigotes on cytological examination of pericardial effusion suggests a possible association between canine leishmaniasis and chronic pericarditis. This finding also supports the importance of cytological examination of pericardial fluid in areas endemic for canine leishmaniasis.

Pericardial effusion in a dog concurrent with carcinoma of unknown primary origin

BACKGROUND

Pericardial effusion (PE) due to secondary metastasis has rarely been reported in dogs.

CASE DESCRIPTION

This case describes clinical signs and further diagnostics regarding metastatic carcinoma of unknown primary origin (CUP) in refractory PE of a dog.

FINDINGS/TREATMENT AND OUTCOME

A nine-year-old, castrated male Shih Tzu dog was referred for evaluation of cough and dyspnea. On presentation, tachypnea, intermittent cough, and muffled heart sounds were noted. Thoracic radiography, electrocardiography, and echocardiography confirmed a PE. No mass lesion was detected at the heart base, aorta, or right atrium (RA). Analysis of the PE showed hemorrhagic cytology, and an idiopathic hemorrhagic PE was tentatively diagnosed. The dog responded to conservative treatment with steroid and diuretics, but the clinical sign recurred. Further evaluation with multi-detector computed tomography (MDCT) was non-diagnostic. The dog died 457 days after initial presentation. Necropsy and histopathology revealed metastatic CUP origin.

CONCLUSION

This case illustrated a rare cause of recurrent PE in dogs.

Pericardial Hemangiosarcoma in a 10-Year-Old Papillon

A 10 yr old papillon was evaluated for lethargy, inappetence, tachypnea, and labored breathing. Physical examination findings included dehydration, tachypnea, tachycardia, and muffled heart sounds. Thoracic radiographs revealed an enlarged cardiac silhouette. Echocardiography revealed a mild volume of pericardial effusion and no evidence of right atrial tamponade or a cardiac-associated mass. Cytological analysis of the pericardial effusion was consistent with blood. There was no evidence of neoplasia. Coagulation parameters were within normal limits. Initial treatment consisted of pericardiocentesis. A subtotal pericardiectomy was later performed. No surgical complications were noted, and the dog was discharged 2 days following surgery. Results of the histological examination of the pericardium revealed hemangiosarcoma. Treatment with doxorubicin was initiated 12 days after surgery, at which time, pulmonary metastasis was suspected. The dog survived for 18 days after subtotal pericardiectomy, when it was euthanized because of complications presumably related to pulmonary metastatic disease. This is the first published report of primary pericardial hemangiosarcoma. The dog had a short survival time; thus, the response to subtotal pericardiectomy combined with adjuvant doxorubicin treatment could not be determined. Pulmonary metastatic disease was suspected 12 days following surgery. Based on this case report, pericardial hemangiosarcoma carries a guarded prognosis.

PCR evaluation of selected vector-borne pathogens in dogs with pericardial effusion

OBJECTIVES

To investigate evidence for selected vector-borne pathogen infections in dogs with pericardial effusion living in a Mediterranean area in which several canine vector-borne diseases are endemic.

MATERIALS AND METHODS

Archived EDTA blood (n=68) and pericardial fluid samples (n=58) from dogs with pericardial effusion (n=68) were included. Dogs without pericardial effusion examined for other reasons were included as controls (n=60). Pericardial effusion was classified as neoplastic in 40 dogs, idiopathic in 23 dogs and of unknown aetiology in 5 dogs. Real-time PCR was performed for Leishmania infantum, Ehrlichia/Anaplasma species, Hepatozoon canis, Babesia species, Rickettsia species and Bartonella species, and sequencing of PCR products from positive samples was used to confirm species specificity.

RESULTS

Vector-borne pathogens were found in 18 dogs: 16 of 68 dogs with pericardial effusion (23·5%) and two of 60 control dogs (3·3%). Positive dogs demonstrated DNA of Leishmania infantum (n=7), Anaplasma platys (n=2, one dog coinfected with Leishmania infantum), Babesia canis (n=5), Babesia gibsoni (n=3) and Hepatozoon canis (n=2). Vector-borne pathogens were more commonly detected among dogs with pericardial effusion than controls (P=0·001). There was no relationship between aetiology of the pericardial effusion and evidence of vector-borne pathogens (P=0·932).

CLINICAL SIGNIFICANCE

Vector-borne pathogens are often detected in dogs with pericardial effusion and require further investigation, especially in dogs with idiopathic pericardial effusion. PCR can provide additional information about the potential role of vector-borne pathogens in dogs with pericardial effusion living in endemic areas.

Septic pericarditis and pneumopericardium in a dog with an oesophageal foreign body

A 5-year-old, intact, male Yorkshire Terrier presented with a 6-day history of lethargy and anorexia. Clinical examination revealed dental plaque accumulation, abdominal effort during respiration and muffled heart sounds. Thoracic radiographs revealed an enlarged globoid cardiac silhouette and mild pneumopericardium, transthoracic ultrasonography revealed a pericardial effusion after which pericardiocentesis, cytology and culture diagnosed septic pericarditis. Three multidrug-resistant bacteria were isolated, two of which have been implicated in gas-producing infections before. Medical management failed to resolve the pericarditis and euthanasia was opted for. A chronic osseocartilaginous oesophageal foreign body cranial to the heart base was found on necropsy. Septic pericarditis and pneumopericardium are rare conditions in dogs. This is the first case to describe a multidrug-resistant polybacterial aetiology causing mild pneumopericardium and only the second case to describe septic pericarditis associated with an oesophageal foreign body.

Cytological diagnosis of cardiac masses with ultrasound guided fine needle aspirates

BACKGROUND

Cardiac masses are uncommon in the canine population. When present, an attempt should be made to obtain a definitive diagnosis. Our goal with this case series was to report that as long as anatomic location permits, obtaining fine needle aspirates (FNAs) for cytological evaluation is practical, safe, and may provide a definitive diagnosis.

METHODS

Our database has been retrospectively searched for cases where FNA of cardiac masses have been performed.

RESULTS

A total of six cases were retrieved. Four dogs were under general anaesthesia and two were sedated. Ultrasound guided transthoracic FNAs were obtained in all cases with only minor complications: mild self-limiting pericardial effusion (n = 1) and one ventricular ectopic complex (n = 1). All dogs were closely monitored during the procedure (pulse oximetry, electrocardiography and blood pressure). A diagnosis was obtained in all cases: inflammation (n = 1), haemangiosarcoma (n = 2), sarcoma (n = 2) and chemodectoma (n = 1).

CONCLUSION

A cytological diagnosis allows clinicians to make appropriate clinical decisions, has dramatic impact on treatment recommendations and gives information about prognosis.

A descriptive review of cardiac tumours in dogs and cats

Cardiac tumours are uncommon in the canine and feline population and often an incidental finding. Common types include haemangiosarcoma (HSA), aortic body tumours (chemodectoma and paraganglioma) and lymphoma. These neoplasms can cause mild to severe, life-threatening clinical signs that are independent of the histological type and may be related to altered cardiovascular function or local haemorrhage/effusion into the pericardial space. Cardiac tumours may require symptomatic treatment aimed at controlling tumour bleeding and potential arrhythmias, and other signs caused by the mass effect. Additional treatment options include surgery, chemotherapy and radiotherapy. For all medical therapies, complete remission is unlikely and medical management, beyond adjunctive chemotherapy in HSA, requires further investigation but combination chemotherapy is recommended for lymphoma. The aim of this report is to summarize and critically appraise the current literature in a descriptive review. However, interpretation is limited by the lack of definitive diagnosis and retrospective nature of most studies.

Fungal myocarditis and pericardial effusion secondary to Inonotus tropicalis (phylum Basidiomycota) in a dog

Fungal disease is a rare cause of pericardial effusion in dogs. This report describes the first case of fungal pericardial effusion and myocarditis secondary to the fungal organism Inonotus tropicalis. A 9-year-old female spayed French bulldog with a multi-year history of treatment with glucocorticoids for management of atopy was presented for exercise intolerance, ascites and weight loss. Physical examination and thoracic imaging revealed enlarged peripheral and cranial mediastinal lymph nodes, left ventricular thickening and cardiac tamponade secondary to pericardial effusion. Fine needle aspiration of the cranial mediastinal lymph node showed pyogranulomatous inflammation with short, thin and poorly septated hyphae. Culture of the aspirate yielded a fungal isolate identified as Inonotus tropicalis based on morphologic features and rRNA gene sequencing. Postmortem examination showed myocardial thickening with multifocal to coalescing, firm, white, ill-defined nodules. Histology confirmed the presence of disseminated fungal infection with extensive myocardial involvement. Inonotus tropicalis is an opportunistic poroid wood-decaying basidiomycete. Infection in this dog was likely the result of chronic immunosuppressive therapy.