Cardiovascular involvement in 8 dogs with blastomyces dermatitidis infection

Clinical presentation, cardiovascular findings, etiology, and outcome of myocarditis in dogs: 64 cases with presumptive antemortem diagnosis (26 confirmed postmortem) and 137 cases with postmortem diagnosis only (2004-2017)

INTRODUCTION

This study describes presentation, cardiovascular abnormalities, etiology, and outcome of canine myocarditis in geographic areas not endemic for Trypanosoma or Leishmania.

ANIMALS

Sixty-four (presumed antemortem diagnosis) and 137 (postmortem diagnosis only) client-owned dogs at two tertiary care facilities were included.

MATERIALS AND METHODS

Medical records of dogs with clinical or histopathological diagnosis of myocarditis were reviewed retrospectively.

RESULTS

Common examination findings in dogs with a presumed antemortem diagnosis included fever (21%) and heart murmur (19%). Median cardiac troponin I was 12.2 ng/mL (range: 0.2-808.0 ng/mL), and troponin exceeded 1.0 ng/mL in 26 of 29 (90%) dogs. Ventricular ectopy was the most common arrhythmia (54%), whereas decreased left ventricular systolic function was the most common echocardiographic abnormality (56%). An infectious etiology was diagnosed in 35 of 64 (55%) dogs. Confirmed infectious etiologies included bacterial sepsis (n = 9) or extension of endocarditis (3), toxoplasmosis or neosporosis (3), parvovirus (2), and one case each of bartonellosis, trypanosomiasis, leptospirosis, and dirofilariasis. Median survival time was 4 days (range: 0-828 days) for all dogs vs. 82 days for dogs who survived at least 2 weeks after diagnosis. Presence of pericardial effusion or azotemia was a significant predictor of non-survival. The most common inflammatory infiltrate on histopathology was neutrophilic (47%), and 20 of 137 (14.5%) dogs had concurrent bacterial endocarditis on postmortem.

CONCLUSIONS

Bacterial infection was the most common confirmed etiology of myocarditis in this study. Prognosis for canine myocarditis is guarded and similar to that reported for infective endocarditis. Criteria for the antemortem diagnosis of canine myocarditis are suggested.

Feline coronavirus-associated myocarditis in a domestic longhair cat

Case summary

A 9-month-old entire male domestic longhair indoor cat presented with a 3-week history of fluctuating fever, weight loss and small intestine diarrhoea, which was unresponsive to antibiotics and supportive treatment. Abdominal ultrasound revealed severe jejunal and ileocolic junction intestinal wall thickening with loss of layering. An enterectomy was performed and histopathology revealed severe pyogranulomatous enteritis with vasculitits, compatible with the diagnosis of feline infectious peritonitis (FIP). Four days after surgery, the cat re-presented with anorexia and acute onset of expiratory dyspnoea. Echocardiography showed left ventricular hypertrophy and bilateral atrial enlargement. Congestive heart failure caused by hypertrophic cardiomyopathy was suspected and treatment with furosemide was started, which led to amelioration of the clinical signs. The following day, four-limb ataxia, hypermetria and bilateral uveitis were evident. Given the persistent anorexia and worsening of the clinical signs, the cat was humanely euthanized and a post-mortem examination was performed. Necropsy revealed multifocal pyogranulomatous lesions involving multiple organs (adrenal glands, kidneys, lungs, brain, myocardium, lymph nodes, liver), compatible with the diagnosis of FIP. Immunohistochemistry performed on the myocardium revealed feline coronavirus-positive macrophages associated with pyogranulomatous lesions, justifying a diagnosis of feline coronavirus-associated myocarditis.

Relevance and novel information

To the authors’ knowledge, the case described here represents the first published report of feline coronavirus-associated myocarditis. This should be considered as a possible differential diagnosis in cats presenting with cardiac-related signs and other clinical signs compatible with FIP.

Blastomycosis in Mammals

Blastomycosis is a serious fungal disease of dogs, humans, and occasionally other mammals caused by geographically restricted, thermally dimorphic Blastomyces species. Blastomycosis is primarily a canine disease, with approximately ten dogs diagnosed for every human case. Dogs also develop disease more rapidly, thus becoming sentinels for possible human disease. Human and canine blastomycosis may differ according to epidemiology/epizoology, clinical features, performance and use of diagnostics, and management.

Concomitant fungal and Mycobacterium bovis infections in beef cattle in Kenya

Bovine tuberculosis is an important zoonosis and accurate diagnosis is important for its surveillance. Post-mortem diagnosis may, however, be compromised by lesions caused by other pathogens. In an investigation on its prevalence in slaughter cattle in Kenya, Mycobacterium bovis and dimorphic fungi were inadvertently identified separately or concurrently in tuberculous lesions. Beef carcasses were inspected for lesions in two abattoirs in Nairobi. Tissues with lesions were collected and transported to the laboratory. Smears of lesions were stained by acid-fast procedure and examined microscopically. Lesions were cultured in Löwenstein-Jensen (LJ) and in BBL TM Mycobacterium growth indicator tubes (MGIT) media. Mycobacteria isolates in LJ medium were identified by DNA typing. Smears of BBLTM MGIT cultures were acid-fast stained and examined microscopically. Tissue sections were stained with periodic acid-Schiff reagent before examination. Of the 929 carcasses examined, 176 had granulomatous lesions. Dimorphic fungi were detected as acid-fast negative cells in 58 (32.9; 33.5%) of the lesion smears, either alone (29.0; 16.4%) or concurrently with acid-fast bacilli (29.0; 16.4%). The fungi were also detected in some BBL TM MGIT-culturesmears and lesioned tissue sections. The fungi were identified, by means of cellular morphology, as Paracoccidioides brasiliensis and Blastomyces dermatitidis. A total of 64 isolates of mycobacteria were recovered in LJ medium, 19 of which were identified as M. bovis. The present report documents native P. brasiliensis infections outside the presumed endemic region and B. dermatitidis infections in a livestock animal. The findings further indicate the importance of dimorphic fungi as a differential diagnosis of bovine tuberculosis in the region.