Case description

An 8-year-old male neutered domestic shorthair cat presented to a primary care veterinarian with a 3-day history of lethargy and inappetence. Clinical examination identified pyrexia (40.5°C) and a grade III/VI left-sided heart murmur. The murmur had first been documented 2 weeks prior, at routine vaccination. The cat was regularly vaccinated, lived indoors, with outside access, and had a previous history of urethral obstruction and periodontal disease. The patient was treated with a 7-day course of clavulanate-potentiate amoxicillin (16 mg/kg q12h) and a single injection of dexamethasone (0.2 mg/kg). Pyrexia resolved with treatment but 3 days after initial presentation the patient was found in lateral recumbency and was referred to an internal medicine department.

The cat was recumbent but alert and responsive on presentation. The patient had pale pink mucous membranes with a prolonged capillary refill time (CRT) of 3 s and weak peripheral pulses. The patient was tachy-pnoeic with a respiratory rate of 60 breaths per minute (bpm) and markedly increased respiratory effort. Cardiac auscultation identified muffled heart sounds bilaterally with a heart rate of 160 beats per minute. The body condition score (BCS) was low at 3/9 (9-point body condition scoring system¹); the cat weighed 3.89 kg and had concomitant poor coat quality. The remaining clinical parameters were within normal limits.

A point-of-care ultrasound was performed upon arrival and identified pericardial effusion with right-sided cardiac tamponade. No pleural or peritoneal effusions were seen. The patient was sedated with butorphanol (0.2 mg/kg), midazolam (0.2 mg/kg) and dexmedetomidine (2 µg/kg) intravenously for pericardiocentesis. A pericardiocentesis catheter (8.2 Fr × 20 cm pericardiocentesis catheter; Surgivet) was inserted and 120 ml of turbid yellow fluid was drained. The patient recovered uneventfully and haemodynamic status was markedly improved after drainage, with good peripheral pulse quality and a CRT of 2 s. The previous dyspnoea had resolved and the respiratory rate was reduced to 40 bpm. Fluid cytological evaluation was consistent with septic exudate. Fluid nucleated cellularity was 50.30 ×10⁹/l, comprising predominantly degenerate neutrophils with bacilli, and a total protein of 34 g/l. The patient developed marked pyrexia of 40.4°C a few hours after the initial pericardiocentesis. At this point, antibiotic treatment was changed from clavulanate-potentiate amoxicillin to pradofloxacin 3 mg/kg PO q24h (Veraflox oral suspension for cats; Elanco) pending bacterial culture and sensitivity results.

Once the patient was stable, further diagnostics were performed. A haematology evaluation identified non-regenerative anaemia with inflammatory leukogram. A biochemical analysis revealed hypoalbuminaemia and a small increase in creatinine kinase above the reference interval. Relevant results are shown in Table 1. A FIV/FeLV snap test (SNAP FIV/FeLV Combo Test; IDEXX) was negative. Urine was collected via cystocentesis. Urinalysis identified moderately concentrated urine (1.032) with unremarkable chemical parameters and no evidence of inflammation or infection. Urine culture was negative. Bartonella PCR on blood was negative. Pericardial effusion culture and antimicrobial resistance revealed profuse growth of Escherichia coli (Table 2).

Table 1

Laboratory results from initial presentation to internal medicine department and postoperatively

Table 2

Pericardial effusion culture and antimicrobial sensitivity panel from an 8-year-old male neutered domestic shorthair cat

Further diagnostic tests were performed 2 days after pericardial drainage. Abdominal ultrasound identified a large 15 × 34 mm cavitated mass protruding from the liver, dorsolateral to the gallbladder on the right (Figure 1). The remaining hepatic parenchyma was unremarkable with no sign of hepatomegaly. The spleen was diffusely enlarged with rounded apices. The splenic parenchyma appeared heterogeneous with multifocal and poorly defined hypoechoic patches. Fine-needle aspirates were collected from the cavitated hepatic mass and septic neutrophilic inflammation was identified on cytological examination. Bacterial culture and isolation identified E coli (Table 3). An abdominal effusion was sampled and was consistent with an inflammatory exudate. Fluid nucleated cells were 120.50 ×10⁹/l, and although no bacteria were observed, an infectious agent was suspected given the findings.

Figure 1

Abdominal ultrasound image. There is a large cavitated mass located dorsolateral to the gallbladder from an 8-year-old male neutered domestic shorthair cat

Table 3

Hepatic mass culture and antimicrobial sensitivity panel from an 8-year-old male neutered domestic shorthair cat

Echocardiography was performed with all standard views assessed. A small quantity of residual echogenic pericardial effusion that was not causing tamponade was noted (Figure 2). The cardiac wall thicknesses and chamber dimensions were within normal limits. A linear shadowing structure in the pericardial space was observed, which ran from the left ventricle apex to the right ventricle free wall. This finding was consistent with gas or foreign material. Post-pericardial drainage thoracic radiography documented a small pleural effusion with a bronchointerstitial pattern, and a moderately enlarged cardiac silhouette.

Figure 2

Echocardiography image from an 8-year-old male neutered domestic shorthair. Right parasternal short-axis view at the level of the papillary muscles. There is a small quantity of pericardial effusion (EFF) diffusely present around the ventricles

Shortly after the hepatic mass sampling, the patient’s pulse quality decreased and the mucous membranes became pale. Given that medical management of a large hepatic abscess would be challenging and the patient’s stability had declined, along with concerns regarding a possible septic peritonitis, an exploratory laparotomy was recommended. Analgesia included methadone 0.15 mg/kg IV, along with the placement of an epidural catheter injected with levobupivacaine and morphine. A ventral midline coeliotomy was performed with a significant volume of ascites identified. On exploration, a hepatic abscess appeared attached to the gall bladder. The gallbladder itself was thickened and adhered to the right medial liver lobe. A right liver lobectomy and cholecystectomy were performed. The spleen appeared grossly abnormal; therefore, a splenectomy was also performed. A median sternotomy and subtotal pericardiectomy were also performed and both body cavities were flushed copiously with sterile saline.

The patient made an uneventful recovery, not requiring admission to the intensive care unit. Pericardial, hepatic and cholecystic histopathological evaluation revealed marked pyogranulomatous inflammation. No neoplastic indication was seen. A splenic histopathological evaluation showed reactive lymphoid hyperplasia with extramedullary haematopoiesis. The patient was discharged on a 2-week course of pradofloxacin 3 mg/kg q24h, which was given to completion.

A clinical reassessment occurred 3 weeks after discharge, due to owner delay. The patient was reported to be clinically well with a significant improvement in both body weight (4.60 kg) and BCS (5/9). The patient’s peripheral pulse was strong and the mucous membranes were pink. The only abnormality noted during examination was a gallop sound with a grade II/VI apical systolic murmur. A new haematological evaluation revealed an improvement in anaemia with haemoglobin within the reference interval. There was also mild neutrophilia, eosinophilia and basophilia. Previous hypoalbuminaemia had resolved. The patient was discharged with a 5-day course of fenbendazole (50 mg/kg q24h) as a prophylactic measure. A further follow-up was declined by the owner.

Discussion

Reports of feline bacterial pericarditis are scarce in the veterinary literature. A retrospective study of 146 feline patients with pericardial effusion did not report a single case with septic aetiology,² highlighting the rarity of this pathology. Septic pericarditis in dogs and cats can develop for numerous reasons, including concurrent pleural or pulmonary infections, penetrating trauma, migrating foreign body or haematogenous spread from other bacterial foci.³ A few cases have been reported in cats.^4–8 The suspected mechanisms underlying reported cases include haematogenous spread,^4,5 localised spread of infection,⁶ migrating foreign body⁷ and unidentified causes.⁸

In this case, the septic pericarditis was suspected secondarily to haematogenous spread from the liver pathology present. E coli is commonly isolated in positive culture samples from dogs and cats with hepatobiliary disease.^9,10 Other common agents include Enterococcus species, Bacteroides species and Clostridium species. These bacteria are commonly found in the gastrointestinal tract and travel to the liver via the biliary system or translocation into the portal vein. A small case series of hepatic abscess in 14 cats found the bacterial populations cultured were often species that populate the gastrointestinal tract, including E coli, which was most commonly cultured, as well as Streptococcus, Enterococcus, Pseudomonas, Enterobacter and Bacteroides species.¹¹ Therefore, given that the infectious agent was E coli, it is suspected that the hepatic abscess was the primary site and that haematogenous spread via the portal vein resulted in seeding to the pericardium.

Hepatic abscesses are relatively uncommon pathological findings in cats. In a published study comprising 58 cats with general hepatobiliary disease, no hepatic abscessation was reported; however, 14% of hepatic and 36% of biliary cultured samples were positive for bacterial growth.¹⁰ This highlights that even within a population of cats with positive hepatic tissue cultures, the presentation of abscesses is uncommon. The indicated treatment for hepatic abscessation in cats is unclear. In human medicine, hepatic abscesses less than 3–5 cm in size are usually drained percutaneously and treated with antibiotics, based on culture and antimicrobial sensitivity. Larger abscesses sometimes require surgical management as well as systemic antibiotics.¹² A small case series documented percutaneous drainage and alcoholisation of hepatic abscesses in five dogs and one cat with excellent results.¹³ This less invasive therapeutic method was not considered in this case given the concerns regarding septic peritonitis. This treatment would be more appropriate in clinically stable patients without additional comorbidities that require surgery.

There are a few veterinary reports that describe septic pericarditis secondarily to suspected haematogenous spread in cats. A single case describes septic pericarditis due to presumed haematogenous spread from the oral cavity in a patient that had recently undergone a dental procedure. The cat was treated solely with medical management and the resolution of pericardial effusion was documented.⁴ An additional report described septic pericarditis associated with a pyometra in an intact female cat. This patient was treated both surgically and medically, with sub-total pericardiectomy and ovariohysterectomy, as well as a 4-week course of enrofloxacin and metronidazole. The patient was clinically well 1 year later.⁵

Due to the low incidence of septic pericarditis in cats,² the most appropriate treatment has not yet been determined. Reported cases suggest some septic pericardial effusions may be managed conservatively with pericardiocentesis, antimicrobial therapy and supportive care^4,8; however, pericardiectomy can be recommended once the patient is stabilised due to reports of subsequent complications.⁶ Constrictive pericarditis is a rare complication of acute pericarditis in humans; the incidence rate is 1.8%, but when considering specific aetiologies, an increased risk was observed in those with purulent pericarditis.¹⁴ In dogs, constrictive pericarditis is most commonly idiopathic or associated with infection,¹⁵ but there are limited reports in cats. A previously reported feline case described the medical management of a cat with bacterial pericarditis, suspected to be secondary to pulmonary infection.⁶ The patient did not survive after developing subsequent constrictive pericarditis. This suggests additional surgical management may be of benefit in feline cases.

In the case presented here, the patient was lost to follow-up, and although a favourable response was seen, the long-term outcome was not available. The gallop sound and grade II/VI apical systolic murmur that was documented at the 3-week check-up was not investigated. Given the bacterial infection suspected from haematogenous spread, endocarditis was a sequel to be considered. In human patients, blood culture is often performed since 40–70% of the blood culture samples from cases of septic pericarditis are positive.¹⁶ In this case, blood culture was not performed but could be considered in future cases.

Conclusions

Septic pericarditis is a rare finding in cats and this case documents a favourable response to a combination of surgical and medical management.