History
A 6-year-old 920-g neutered male ferret was presented for a 3-week history of respiratory distress, ataxia, and weakness. The ferret had a previous history of insulinoma and adrenal disease, which were managed with unknown doses of prednisolone and diazoxide as well as deslorelin implants. On physical examination, the patient was quiet, alert, responsive, and had a low body condition score (3/9). There was a palpably enlarged spleen, mild fluid wave, increased respiratory rate and effort, and muffled heart sounds ventrally. No murmur was auscultated. A thoracic point-of-care ultrasound on the conscious patient showed pleural effusion. The patient was hospitalized overnight on oxygen therapy, and respiratory effort worsened. A therapeutic thoracocentesis was performed, and an estimated 80 to 100 mL of serosanguinous fluid was removed. A CBC and plasma biochemistry panel were within normal ranges.1 The patient was anesthetized, and an echocardiogram was performed (Figure 1).
Two-dimensional echocardiographic images (right parasternal long-axis 4-chamber view) of a 6-year-old neutered male ferret with muffled heart sounds and increased respiratory effort.
Citation: Journal of the American Veterinary Medical Association 263, 3; 10.2460/javma.24.08.0561
Diagnostic Imaging Findings and Interpretation
Echocardiography showed severe right atrial dilation and right ventricular dilation and a thickened, elongated, and dysplastic anterior tricuspid valve leaflet. The tips of the anterior tricuspid valve leaflet did not coapt with the septal leaflet and connected directly to thin, elongated papillary muscles; the septal leaflet was tethered directly to the septum. Additionally, the mitral valve leaflets were thickened with nodular tips. Measures of systolic function were normal. Color Doppler imaging showed severe tricuspid regurgitation and mild mitral regurgitation. Anechoic pleural effusion was present. No other significant abnormalities were reported. The ferret was diagnosed with tricuspid valve dysplasia and secondary right-sided congestive heart failure, along with chronic degenerative mitral valve disease (Figure 2; Supplementary Video S1).
Same echocardiographic images as in Figure 1. The septal leaflet of the tricuspid valve is tethered to the septum by short chordae (large arrow; panel A). The parietal leaflet is elongated and attached to abnormal papillary muscle structure (small arrow; panel A). The apical mitral valve leaflet is thickened and rounded (arrow; panel B). LA = Left atrium. LV = Left ventricle. RA = Right atrium. RV = Right ventricle.
Citation: Journal of the American Veterinary Medical Association 263, 3; 10.2460/javma.24.08.0561
Treatment and Outcome
The patient was discharged with clopidogrel (21 mg/kg, PO, q 24 h) for a suspect portal vein thrombosis identified on ultrasound, pimobendan (0.68 mg/kg, PO, q 12 h) to improve the heart’s contractility, and furosemide (3.3 mg/kg, PO, q 12 h) to manage fluid overload. These medications were prescribed to be given until otherwise directed. Approximately 2 weeks later, the patient presented for a recheck appointment with signs of respiratory distress (tachypnea, dyspnea) and weakness. On physical examination, the ferret was in poor body condition (body condition score 2/9) and had a mild abdominal fluid wave. The ferret was also found to have a low core body temperature (36.1 °C [96.9 °F]). A thoracic and abdominal point-of-care ultrasound revealed fluid in the pleural and peritoneal spaces. The ferret’s condition on presentation was not believed to be due to a lack of treatment response but rather the owner stating that the medications were not administered as prescribed.
Blood was collected and a plasma biochemistry panel repeated, which indicated elevated renal values (BUN, 63 mg/dL [reference range, 16 to 43 mg/dL]; creatinine, 1.79 mg/dL [reference range, 0 to 1.6 mg/dL]), which were attributed to dehydration.1 However, because of the reoccurrence of cavitary effusion, the cardiologist made the recommendation to increase the dose frequency of furosemide from every 12 hours to every 8 hours and increase the amount of water consumed by the patient. The patient was discharged the same day, and the owners were further instructed to call if they were having difficulty with medication compliance.
Twenty-two days later, the patient died at home. The body was submitted for necropsy, and the gross postmortem examination revealed 22 mL of serosanguinous pleural effusion and a small (unmeasured) amount of pericardial effusion (Figure 3). There was mild thickening of the tricuspid valve leaflet with fusion of the septal leaflet to the ventricular septum and few localized 1- to 2-mm pale-pink nodules. There was a moderate amount of white foam throughout the trachea from the larynx to the carina. The lungs were mottled dark red and were subjectively heavy on palpation. The liver had a granular capsular surface, and the abdominal cavity contained 6 mL of translucent fluid. Histopathologic examination revealed multifocal to coalescing areas of interstitial and replacement fibrosis throughout the myocardium of the left and right ventricle, as well as the interventricular septum. The tricuspid valve leaflets were mildly expanded with small nodules consisting of myxomatous matrix. There was concurrent evidence of pulmonary edema and chronic passive congestion in the liver.
A—The thoracic cavity is filled with straw-colored fluid (hydrothorax; asterisks). B—Right ventricle. The septal leaflet of the tricuspid valve is adhered to the interventricular septum and has multiple tan nodules (arrows).
Citation: Journal of the American Veterinary Medical Association 263, 3; 10.2460/javma.24.08.0561
Comments
Cardiac disease is a common finding in pet ferrets, with dilated cardiomyopathy and endocardiosis most frequently diagnosed.2 Clinical signs often associated with heart disease include lethargy, anorexia, tachypnea, hind limb weakness, exercise intolerance, and syncope.2 On physical examination, auscultation of the heart may reveal heart murmurs, arrhythmias, and muffled heart sounds.2 Auscultation of the lungs may reveal crackles, muffled lung sounds, or increased bronchovesicular sounds, which can be associated with pleural effusion and lung edema secondary to cardiac disease.2 Physical examination findings can help determine which diagnostic tests to pursue (eg, thoracic radiographs, echocardiogram, electrocardiogram, evaluation of blood parameters).
In this case, echocardiography was pursued due to the suspicion of structural heart disease and congestive heart failure. On the basis of the abnormalities seen on the echocardiogram, including the tricuspid valve connecting to thin, elongated papillary muscles, the septal leaflet tethered directly to the septum, and the mitral valve leaflets thick with nodular tips, the ferret was diagnosed with tricuspid valve dysplasia and degenerative mitral valve disease. This diagnosis would have been unattainable with radiographic imaging alone; echocardiography is considered the primary diagnostic tool for congenital heart disease, as it allows for a functional assessment of the heart.3
The echocardiogram indicated that the ferret was in right-sided heart failure due to the severe tricuspid valve and mild mitral valve regurgitation and pleural effusion, which were caused by the valvular changes. These findings were supported on necropsy, which revealed pulmonary congestion and edema, chronic hepatic passive congestion, and tricavitary effusion. Histologic changes in the heart consisting of myocardial fiber loss and fibrosis seen in both ventricles were suggestive of an underlying cardiomyopathy. The gross and histological changes seen on the tricuspid valve were consistent with both valvular dysplasia and endocardiosis and correlated with the functional analysis revealed by the echocardiogram.
Tricuspid valve dysplasia has rarely been described in ferrets.4,5 The case described in the present report highlights the importance of echocardiography as a diagnostic tool for zoological companion animals exhibiting signs of congestive heart failure to most appropriately diagnose and manage a spectrum of cardiac diseases.
Supplementary Materials
Supplementary materials are posted online at the journal website: avmajournals.avma.org.
Acknowledgments
None reported.
Disclosures
The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.
Funding
The authors have nothing to disclose.
References
- 1.↑
Fox JG. Normal clinical and biological parameters. In: Fox JG, Marini RP, eds. Biology and Diseases of the Ferret. John Wiley and Sons Inc; 2014:157-185. doi:10.1002/9781118782699.ch7
- 2.↑
van Zeeland YRA, Schoemaker NJ. Ferret cardiology. Vet Clin North Am Exot Anim Pract. 2022;25(2):541-562. doi:10.1016/j.cvex.2022.01.007
- 3.↑
Saunders AB. Key considerations in the approach to congenital heart disease in dogs and cats. J Small Anim Pract. 2021;62(8):613-623. doi:10.1111/jsap.13360
- 4.↑
Jekl V, Agudelo C, Hauptman K. First case of congenital tricuspid valve dysplasia imitating atrial septal defect in a ferret. In: Proceedings of the 1st International Conference on Avian, Herpetological and Exotic Mammal Medicine. European College of Zoological Medicine; 2013:103.
- 5.↑
Zborovska H. Heart Diseases in Ferrets. Diploma thesis. University of Veterinary and Pharmaceutical Sciences Brno; 2016.
