Immunohistochemical characterisation of the lesions of canine idiopathic pericarditis

Pathological Findings of Canine Idiopathic Pericarditis and Pericardial Mesotheliomas: Correlation with Clinical and Survival Data

Idiopathic pericarditis (IP) and pericardial mesothelioma (PM) are causes of pericardial effusion in dogs. Pericardiectomy can be a definitive treatment in the case of idiopathic pericardial effusion or a short-term intervention for mesothelioma. The aim of the present study was to investigate which histopathologic parameters are correlated with clinical outcomes in a cohort of dogs that underwent pericardiectomy. The histopathological findings of 22 IPs and 5 PMs were compared with clinical and survival data and the immunohistochemical characterization of immune cells (CD3, CD79α, Iba1). In IP, the mesothelium was lost in 20 cases, reactive in 9, atypical in 3, and mesothelial papillary hyperplasia (MPH) was observed in 4 cases. Numerous macrophages were found in both IPs and PMs especially at the superficial layer of the pericardium. T lymphocytes were observed in mild to moderate numbers and were more numerous than B lymphocytes in both IPs and PMs. MPH was correlated with the quantity of lymphoplasmacytic infiltrate in the superficial layer, inversely related to the thickness of the pericardium, and associated with a longer overall survival. Pericardial fibrosis was present in 19 out of 22 IPs and in all mesotheliomas and was correlated with increased time from initial presentation and pericardiectomy and lymphoplasmacytic infiltrate in the deep zone. Pericardial thickness was correlated with the amount of lymphoplasmacytic and macrophagic infiltrate in the deep zone. Mesothelioma was associated with an increased number of pericardiocentesis procedures before pericardiectomy and with the presence of macrophages in the superficial pericardial layer, edema, fibrin, and hemorrhage. Disease-free interval and overall survival were significantly shorter in patients with mesothelioma compared with IP.

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.

Cardiac magnetic resonance in the differentiation of neoplastic and nonneoplastic pericardial effusion

BACKGROUND

Cardiac magnetic resonance (CMR) is the imaging modality of choice for cardiac tumors in people. Although neoplastic pericardial effusion (PE) carries a poor prognosis, benign idiopathic pericardial effusion does not. Definitive diagnosis is critical for surgical intervention, but currently available diagnostic techniques such as echocardiography and pericardial fluid cytology often are inconclusive.

HYPOTHESIS/OBJECTIVE

Describe CMR findings associated with PE and determine whether CMR aids in differentiation of benign and neoplastic causes of PE.

ANIMALS

Eight client-owned dogs with PE diagnosed by transthoracic echocardiography (TTE).

METHODS

CMR was performed with a 1.5 T, including dark blood, steady-state free procession cine, pre- and postcontrast T1-weighted imaging, and delayed inversion recovery prepped imaging.

RESULTS

CMR confirmed a cardiac mass and supported suspected tumor type in 4 dogs with suspected hemangiosarcoma. In 1 equivocal TTE case, CMR did not demonstrate a mass, but neoplasia was later diagnosed. In another equivocal case, CMR did not demonstrate a mass but showed findings consistent with a pericardiocentesis complication. In 1 dog without evidence of cardiac neoplasia, abdominal magnetic resonance imaging identified presumptive hepatic and splenic metastases. On reevaluation of the original CMR study, the 2 equivocal cases that were interpreted as tumor negative were reassessed as tumor positive.

CONCLUSIONS AND CLINICAL IMPORTANCE

CMR did not substantially improve diagnosis of cardiac tumors compared with TTE in these 8 cases, but it yielded useful descriptive information regarding extent, anatomic location, and potential tumor type and confirmed that CMR requires extensive additional training for tumor identification.

Idiopathic pericarditis in dogs: no evidence for an immune-mediated aetiology

OBJECTIVE

To ascertain whether specific immunological changes are associated with canine pericardial effusion due to idiopathic pericarditis.

METHODS

In this prospective study, serum antinuclear antibody and serum and pericardial fluid immunoglobulin (Ig) G, Ig M and Ig A concentrations were measured in dogs with pericardial effusion due to idiopathic pericarditis or pericardial neoplasia. The secretory index relative to albumin concentration was calculated in order to distinguish between Ig actively secreted into the pericardial fluid and that derived from the blood accumulating within the pericardial sac. Statistical analysis was performed comparing the results obtained between the two groups of dogs.

RESULTS

Only three dogs were antinuclear antibody positive; two of these dogs had idiopathic pericarditis and one had neoplasia. Mean serum Ig M and Ig A concentrations were lower than the reference values in both groups, and the secretory indices for Ig M and Ig A were greater than 1.0. However, there was no significant difference with respect to any Ig measurement between the two groups of dogs (P>0.1).

CLINICAL SIGNIFICANCE

The results of the present study do not support the hypothesis that canine idiopathic pericarditis has a significant 'immune-mediated' aetiology or immunological features that distinguish it from the pericardial changes associated with local neoplastic disease.

Long-term survival of 23 dogs with pericardial effusions

Twenty-three dogs with pericardial effusions were identified from case records made between 1992 and 2000. Fourteen of the 23 were diagnosed with idiopathic pericardial effusions, and three of these were treated successfully by one pericardiocentesis. In the remaining 11 cases the pericardial effusion recurred; six cases were managed long-term by either two (three cases), three (two cases), or 11 repeated pericardiocenteses, and the remaining five were treated by pericardiectomy. The median survival time of the six dogs treated by repeated pericardiocentesis was five years and nine days.

A retrospective study of clinical findings, treatment and outcome in 143 dogs with pericardial effusion

A retrospective study of 143 dogs with pericardial effusion is presented, including a statistical analysis of survival time. Cases were classified into those in which a mass was seen on echocardiography (echo-positive) and those in which no mass could be identified (echo-negative). Forty-four dogs were echo-positive and 99 were echo-negative. The median survival time (MST) was 1068 days for echo-negative dogs and 26 days for echo-positive dogs. Dogs with a history of collapse were more likely to present with a mass on echocardiography. Those presenting with collapse had an MST of 30 days compared with 605 days for those without collapse. Echo-negative dogs tended to present with ascites and generally had a larger volume of pericardial effusion. The median survival for dogs presenting with ascites was 605 days compared with 45 days for those without ascites. Among echo-negative dogs, 64 per cent had a relapse of their effusion. Subtotal pericardiectomy was performed in 31 echo-negative dogs. The procedure had a perioperative mortality of 13 per cent but provided a favourable long-term prognosis. Dogs undergoing pericardiectomy had a median survival of 1218 days compared with 532 days for those not undergoing surgery.