Suspected Bartonella-associated myocarditis and supraventricular tachycardia in a cat

Flash pulmonary oedema associated with paroxysmal supraventricular tachycardia: report of two cases

Case summary

We describe two cats that had episodic tachypnoea and increased respiratory effort during periods of paroxysmal supraventricular tachycardia (SVT). Thoracic radiographs at the time of clinical signs were consistent with cardiogenic pulmonary oedema. Echocardiography following stabilisation revealed a hypertrophic cardiomyopathy phenotype with normal left atrial size in both cats. The first cat was initially treated with diltiazem, but this did not reduce the frequency of the clinical episodes. Diltiazem was switched to atenolol and the cat remained well without further recurrence. At the time of writing, the cat was reported to be well, 3 years after the initial diagnosis of SVT. The second cat was first managed with diltiazem and was then transitioned to atenolol due to recurrent clinical episodes. The episodes were less frequent with atenolol but still present. Therefore, atenolol was changed to sotalol. The cat remained well on sotalol for 2 years with only one recurrent episode during a painful event. The patient then suffered a sudden cardiac death, 5 years after the initial diagnosis of SVT.

Relevance and novel information

To our knowledge, this is the first report that describes flash pulmonary oedema developing secondary to episodic paroxysmal SVT in cats. Despite the severity and speed of respiratory compromise, prognosis may be good with an adequate arrhythmia control.

Treatment of a cat with presumed Bartonella henselae-associated immune-mediated hemolytic anemia, fever, and lymphadenitis

A 2.5‐year‐old castrated male cat presented with fever and marked generalized lymphadenopathy of 4‐months duration, despite treatment with amoxicillin‐clavulanate/marbofloxacin. Abnormalities were not detected on complete blood count, serum chemistry, and FIV/FeLV test apart from a borderline, non‐regenerative anemia. Peripheral lymph node fine needle aspirations revealed a marked increase in the percentage of intermediate‐ and lymphoblastic‐lymphocytes in addition to reactive macrophages. Three weeks after presentation, the cat developed a severe, regenerative, immune‐mediated hemolytic anemia (IMHA) which responded to immunosuppressive therapy. Fever and lymphadenopathy persisted. Peripheral lymph nodes tested positive for Bartonella henselae DNA in real‐time PCR assay and sequencing. Treatment with pradofloxacin and doxycycline resulted in resolution of clinical signs, and negative PCR tests. Despite its reported low pathogenicity, B. henselae infection should also be considered in cats with protracted unexplained fever, lymphadenitis, and IMHA. Furthermore, a combination of pradofloxacin and doxycycline might be considered in cats with bartonellosis given its apparent clinical efficacy.

Identification of Streptococcus suis in a cat with endomyocarditis

Case summary

A 3-year-old neutered male domestic mediumhair cat was evaluated for a 4-month history of a fever that was responsive to pradofloxacin. A grade III/VI left parasternal systolic heart murmur was noted on examination. Findings on thoracic radiography were consistent with left-sided congestive heart failure and findings on echocardiographic examination suggested endomyocarditis. Aerobic blood cultures yielded growth of a Streptococcus species that was identified as Streptococcus suis using both matrix-associated laser desorption ionization-time of flight mass spectrometry and 16S rRNA gene sequencing. The cat was treated but clinically deteriorated and was euthanized 23 days after diagnosis.

Relevance and novel information

To our knowledge, this is the first report of S suis bacteremia, an emerging pathogen, in association with endomyocarditis in the cat. This case also highlights the role of echocardiography to document progressive hemodynamic changes as a result of valvular erosion in the course of infective endocarditis treatment and the role of blood cultures as a diagnostic tool in cats presenting with fever.

Supraventricular tachycardia in 23 cats; comparison with 21 cats with atrial fibrillation (2004-2014)

INTRODUCTION

Supraventricular tachycardia (SVT) has not been well described in cats. The aim of this study was to describe the signalment, clinical findings, and outcome for cats with SVT versus cats with atrial fibrillation (AF).

ANIMALS

Forty-four client owned cats are included in the study. 23 cats with SVT and 21 with AF.

METHODS

This is a retrospective study. Clinical characteristics were compared between groups using a two-sample t-test or Mann-Whitney U test. Kaplan-Meier survival curves were generated to assess for impact of rhythm diagnosis, presence of ventricular arrhythmia, left atrial diameter, heart rate and congestive heart failure (CHF) status on cardiac death. Differences in survival between groups were compared using Mantel-Cox logrank comparison of Kaplan-Meier survival curves.

RESULTS

Cats with supraventricular arrhythmias most commonly presented with respiratory distress (10 of 44 cats). Cats with AF had a slower median heart rate (220 [range: 180-260 beats per minute (bpm)] compared with cats with SVT (300 [range: 150-380] bpm, p < 0.001). All cats with AF had structural heart disease, whereas 4 cats with SVT had no structural abnormalities. Left atrial diameter was significantly larger in cats with AF (23.7 (16.2-40.1) mm compared with 19.1 (12.8-31.4) mm in SVT cats; p = 0.02). Median survival was 58 days (1-780) in cats with AF and 259 days (2-2295) in cats with SVT (p = 0.1). Cats with signs of CHF had a shorter survival time (p = 0.001).

CONCLUSIONS

Most cats with AF or SVT have advanced structural heart disease. Some cats with SVT had structurally normal hearts, suggesting that SVT in cats is not always a consequence of atrial enlargement.

Bartonella spp. as a Possible Cause or Cofactor of Feline Endomyocarditis-Left Ventricular Endocardial Fibrosis Complex

Endomyocarditis is a commonly detected post-mortem finding in domestic cats presenting for sudden onset cardiovascular death, yet the aetiology remains unresolved. Cats are documented reservoir hosts for Bartonella henselae, the infectious cause of cat scratch disease in man. Various Bartonella spp. have been associated with culture-negative endocarditis, myocarditis and sudden death in man and animals. We hypothesized that Bartonella spp. DNA could be amplified more often from the hearts of cats with feline endomyocarditis-left ventricular endocardial fibrosis (FEMC-LVEF) complex compared with cats with hypertrophic cardiomyopathy (HCM) or cats with grossly and microscopically unremarkable hearts (designated non-cardiac disease controls). Formalin-fixed and paraffin wax-embedded, cardiac tissues from 60 domestic and purebred cats aged 3 months to 18 years were examined, and histological features were recorded. Cardiac tissue sections were tested for Bartonella DNA using multiple 16-23S intergenic transcribed spacer region polymerase chain reaction (PCR) primer sets, including two Bartonella genera, a Bartonella koehlerae species-specific and a Bartonella vinsonii subsp. berkhoffii-specific assay, followed by DNA sequence confirmation of the species or genotype. Special precautions were taken to avoid DNA cross-contamination between tissues. Bartonella spp. DNA was amplified by PCR and sequenced from 18 of 36 cats (50%) with FEMC-LVEF and 1/12 (8.3%) cats with HCM. Bartonella spp. DNA was not amplified from any non-cardiac disease control hearts. Based on PCR/DNA sequencing, one Bartonella spp. was amplified from 10 cats, while the remaining eight were coinfected with more than one Bartonella spp. To our knowledge, this study represents the first documentation of B. vinsonii subsp. berkhoffii genotype I infection in cats (n = 11). Fluorescence in-situ hybridization testing facilitated visualization of Bartonella bacteria within the myocardium of four of seven PCR-positive FEMC-LVEF hearts. Collectively, these findings support the hypothesis that Bartonella spp. may play a primary role or act as a cofactor in the pathogenesis of FEMC-LVEF. Studies involving cats from other geographical regions and definitive demonstration of Bartonella spp. within regions of inflammation are needed to confirm an association between Bartonella spp. and FEMC-LVEF induced morbidity and mortality in cats.

Transient myocardial thickening in a Bartonella henselae-positive cat

A 3-year-old castrated male domestic shorthair presented to the Cornell University Hospital for Animals for acute onset respiratory distress. Thoracic radiographs, echocardiogram, and electrocardiogram (ECG) revealed left-sided congestive heart failure, myocardial thickening with left atrial dilation, and sinus rhythm conducted with a left bundle branch block, respectively. Cardiac troponin I was elevated and continued to increase over 36 h (1.9 ng/mL, 3.1 ng/mL, and 3.5 ng/mL, sequentially every 12 h). The cat tested positive for Bartonella henselae and was treated with azithromycin (30 mg/kg by mouth (PO) every 24 h for 30 days), along with furosemide (1 mg/kg PO every 24 h), benazepril (0.4 mg/kg PO every 24 h), pimobendan (0.23 mg/kg PO every 12 h), and clopidogrel (18.75 mg PO every 24 h). Reevaluation at 6 weeks revealed normal respiratory rate on physical examination, normal cardiac structures and function on echocardiogram, resolution of left bundle branch block on ECG, and normal cardiac troponin I levels (0.06 ng/mL). All medications were discontinued at this time, and the cat continued to do well 5 months after reevaluation. Here, we report a case of transient myocardial thickening in a cat that was also positive for B. henselae.

Infective endocarditis in 13 cats

INTRODUCTION

To describe the clinical presentation, clinicopathological abnormalities and outcomes of a series of cats diagnosed with infective endocarditis (IE) at two tertiary care referral institutions.

ANIMALS

Thirteen client-owned cats presenting to the cardiology or emergency services of tertiary referral institutions with a diagnosis of endocarditis based on the modified Duke criteria.

MATERIALS AND METHODS

Retrospective case series. Medical records were reviewed to extract relevant data. In addition, cases that had cardiac tissue available were evaluated by polymerase chain reaction for the presence of Bartonella DNA.

RESULTS

Prevalence of feline IE was 0.007%. Cats with endocarditis tended to be older (median age: 9 years, range: 2-12 years) and no sex or breed was overrepresented. Commonly encountered clinical signs included respiratory distress (n = 5) and locomotor abnormalities of varying severity (n = 5). Echocardiographic examination detected valvular lesions consistent with endocarditis on the aortic (n = 8) or mitral (n = 5) valves. Nine cats were diagnosed with congestive heart failure at the time of endocarditis diagnosis. Overall, prognosis was grave with a median survival time of 31 days.

CONCLUSIONS

In contrast to dogs, cats with IE typically present with clinical signs consistent with cardiac decompensation and locomotor abnormalities suggestive of either thromboembolic disease or inflammatory arthritis. Given the advanced state of disease when diagnosis typically occurs, prognosis is grave.

Bartonella species infection in cats: ABCD guidelines on prevention and management

OVERVIEW

Over 22 Bartonella species have been described in mammals, and Bartonella henselae is most common worldwide. Cats are the main reservoir for this bacterium. B henselae is the causative agent of cat scratch disease in man, a self-limiting regional lymphadenopathy, but also of other potentially fatal disorders in immunocompromised people.

INFECTION

B henselae is naturally transmitted among cats by the flea Ctenocephalides felis felis, or by flea faeces. A cat scratch is the common mode of transmission of the organism to other animals, including humans. Blood transfusion also represents a risk.

DISEASE SIGNS

Most cats naturally infected by B henselae do not show clinical signs but cardiac (endocarditis, myocarditis) or ocular (uveitis) signs may be found in sporadic cases. B vinsonii subspecies berkhoffii infection has reportedly caused lameness in a cat affected by recurrent osteomyelitis and polyarthritis.

DIAGNOSIS

Isolation of the bacterium is the gold standard, but because of the high prevalence of infection in healthy cats in endemic areas, a positive culture (or polymerase chain reaction) is not confirmatory. Other compatible diagnoses must be ruled out and response to therapy gives a definitive diagnosis. Serology (IFAT or ELISA) is more useful for exclusion of the infection because of the low positive predictive value (39-46%) compared with the good negative predictive value (87-97%). Laboratory testing is required for blood donors.

DISEASE MANAGEMENT

Treatment is recommended in the rare cases where Bartonella actually causes disease.