Chronic nonproductive cough in a 9-year-old female spayed Miniature Poodle

Brian Thomsen VCA West Coast Specialty and Emergency Animal, Hospital Fountain Valley, CA

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 DVM
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Elizabeth Huynh VCA West Coast Specialty and Emergency Animal, Hospital Fountain Valley, CA

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 DVM, MS, DACVR
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Arathi Vinayak VCA West Coast Specialty and Emergency Animal, Hospital Fountain Valley, CA

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 DVM, DACVS-SA, ACVS Fellow, Surgical Oncology

History

A 9-year-old 3.98-kg female spayed Miniature Poodle was referred for further evaluation of an abnormality noted on thoracic radiographs. These radiographs were done prior to a dental cleaning as part of a routine senior wellness plan. The dog had a several year history of a mild, dry, nonproductive cough that was marginally worse for the previous 2 months. No medications were dispensed, a dental prophylaxis was not performed, and referral to a specialist was made.

On examination, the patient was bright, alert, and responsive. Vital signs were evaluated and found to be within normal limits. Moderate dental disease and a grade 2/4 medially luxating patella on the left pelvic limb were noted on physical examination. No cough was able to be elicited. No other abnormalities were found on physical examination. A CBC and serum biochemical analyses was available from 5 months prior and showed no abnormalities. Thoracic radiographs performed prior to referral were reviewed. Three-view thoracic radiographs are available in Figure 1.

Figure 1
Figure 1

Right lateral (A), left lateral (B), and ventrodorsal (C) thoracic radiographs from the referring veterinarian.

Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.11.0497

Diagnostic Imaging Findings and Interpretation

The 3-view thoracic radiographs were evaluated by 2 board-certified veterinary radiologists. In the right caudoventral thorax, a focal, round to broad-based, smooth, soft tissue opacity was noted (Figure 2). The cranial aspect of the opacity is partially superimposed with the caudal aspect of the cardiac silhouette and caudally the border cannot be delineated from the right crus of the diaphragm on the ventrodorsal projection. The remainder of the pulmonary parenchyma was noted to be unremarkable. Given the history, signalment and radiographic appearance the primary differential diagnosis for the opacity was primary pulmonary neoplasia of the right caudal lung lobe. Granuloma, abscess, cyst, diaphragmatic mass, hernia or eventration were considered as other differentials.

Figure 2
Figure 2

Right lateral (A), left lateral (B), and ventrodorsal (C) thoracic radiographs from the referring veterinarian. The white arrow denotes the focal round to broad-based soft tissue structure noted by the radiologists.

Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.11.0497

A triple phase CT scan of the thorax and abdomen was performed for staging and surgical planning under general anesthesia. Evaluation of the CT in transverse, sagittal, and dorsal reformats showed a lobular, soft tissue attenuating structure extending through the caval foramen into the plica vena cava (Figure 3). This structure was isoattenuating to and contiguous with the central division of the liver with a venous branch that appeared separate from the right division extending into it (Figure 3). The right medial lobe was considered most likely to be involved but a definitive lobation could not be determined with the imaging available. A caval foramen hernia was diagnosed. There was no evidence of compression of the vena cava or the lungs. Also noted on the CT was minimal mineral attenuating debris within the gallbladder and soft tissue attenuating cutaneous nodules, thought most likely to be incidental. The remainder of the thorax and abdomen was normal. An ultrasound of the area performed out of academic interest showed the herniated contents to be isoechoic to the liver and contiguous with the central division (Figure 4).

Figure 3
Figure 3

Individual images from the CT scan of the chest and abdomen in sagittal (A), transverse (B), and dorsal (C) reformats. The hernia is denoted in all images by a black asterisk. The caudal vena cava is denoted as CVC on images A and B. The left hepatic vein (LHV) and portal vein (PV) are visible in image C. The black arrow in image C points to a small venous branch from the central division that can be seen passing into the hernia.

Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.11.0497

Figure 4
Figure 4

A still image captured during abdominal ultrasound. The hernia (HER) can be seen just cranial to the diaphragm denoted by a white arrow. The liver (LVR), heart (HRT), and caudal vena cava (CVC) are also visible.

Citation: Journal of the American Veterinary Medical Association 261, 6; 10.2460/javma.22.11.0497

Treatment and Outcome

The patient recovered from anesthesia uneventfully. After diagnosis of the hernia and discussion with the surgery, radiology, and internal medicine services it was determined that the caval foramen hernia was likely incidental and unrelated to the chronic history of mild coughing. No surgical intervention was pursued, and a referral was made to the internal medicine department for continued workup of the chronic mild cough. No additional diagnostics were performed at the time of this article.

Comments

For the dog in this case, a caval foramen hernia of a portion of the central division of the liver was diagnosed. Caval foramen hernia is a rarely described condition of the dogs and humans where abdominal contents (typically right lateral liver lobe) have herniated through the diaphragmatic caval foramen into the thoracic cavity.13 In general, diaphragmatic hernias can be broken down into traumatic and congenital categories.4 Although it cannot be definitively proven, the hernia in this case is presumed to be congenital given the lack of trauma history and pet ownership from the time of 8 weeks of age. The diaphragm has 3 openings between the thorax and abdomen; esophageal hiatus, aortic hiatus, and caval foramen.4 The caval foramen is found within the dorsal portion of the central tendon of the diaphragm. The caudal vena cava’s adventitia is normally fused with the tendon creating a seal around it.4 If this seal is disrupted it creates the opportunity for herniation.

In this case, the hernia was incorrectly diagnosed as a pulmonary mass on thoracic radiographs. Radiographs are typically considered the most useful and practical method for diagnosing diaphragmatic hernia.4 However, there is little information on their efficacy for diagnosis of caval foramen hernia. There are several case reports in the veterinary and human literature describing the misdiagnoses of caval foramen or other diaphragmatic hernias on radiographs.1,2,5 In a study of 7 canine caval foramen hernias, 57% were misdiagnosed as intrathoracic lesions such as a thoracic mass.1 The same study proposed that radiographic findings including a broad base to the opacity along the diaphragm, dome-shape to the opacity, and a caudal or caudoventral mediastinal nodule/mass pattern could move caval foramen hernia higher on the differential diagnosis list than lung tumors, diaphragmatic masses, pulmonary or pleural origin granulomas, cysts, and abscesses.1 These features may be shared with other hernia types so location in close proximity to the vena cava can help in differentiation. Re-review of the radiographs in this case suggests that a caval foramen hernia should have been considered higher on the differential list for this opacification along the diaphragm. The use of ultrasound for diagnosis of diaphragmatic hernia is well described but not specifically validated for caval foramen hernia beyond case reports.3,4 Ultimately, a triple phase CT was used to obtain a diagnosis in this case and appears to offer a reliable method for diagnosis and characterization of caval foramen hernia.1

The clinical relevance of caval foramen hernia in dogs is unclear with little information in the veterinary literature on the condition.1 Caval foramen hernia in humans is also rare and offers little guidance on how we ought to proceed in veterinary medicine. There has been a report in the human literature of caval foramen hernia resulting in caval obstruction and pulmonary embolism.5 This case was surgically repaired resulting in resolution of the caval obstruction. Anticoagulant therapy was used to treat the pulmonary embolism. While there is no consensus on when this type of hernia should be surgically addressed, progressive herniation of the liver through the defect, obstructive caudal vena caval dilation, congestion of hepatic veins, and Budd-Chiari-like syndrome may be indications for surgical intervention.1 It appears that the majority of veterinary cases are asymptomatic and intervention in these patients is likely not warranted.1 In this case there was no evidence of caval compression or related clinical signs thus no surgical treatment was pursued.

This case highlights that on thoracic radiographs alone, the many types of diaphragmatic hernias, including caval foramen hernias, can be difficult to differentiate from primary lung tumors, diaphragmatic masses, pulmonary or pleural origin granulomas, cysts, and abscesses. Advanced imaging with a CT scan in these patients is needed to make an accurate diagnosis, prognosis, and treatment plan. Misdiagnosis on thoracic radiographs alone can lead to catastrophic errors in case management and increase patient morbidity. Although uncommonly diagnosed, caval foramen herniation should be included on the differential diagnosis list of caudal thoracic mass lesions abutting the diaphragm over the region of the caudal vena cava.

Acknowledgments

No third-party funding or support was received in connection with this case or the writing or publication of the manuscript. The authors declare that there were no conflicts of interest.

References

  • 1.

    Kim J, Kim S, Jo J, Lee S, Eom K. Radiographic and computed tomographic features of caval foramen hernias of the liver in 7 dogs: mimicking lung nodules. J Vet Med Sci. 2016;78(11):16931697. doi:10.1292/jvms.16-0161

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2.

    Ng CS, Lee TW, Wan S, Yim AP. Caval foramen hernia masquerading as a thoracic mass. Can J Surg. 2006;49(1):6465.

  • 3.

    Park J, Lee HB, Jeong SM. Caval foramen hernia in a dog: preoperative diagnosis and surgical treatment. J Vet Med Sci. 2020;82(11):16021606. doi:10.1292/jvms.19-0575

    • Search Google Scholar
    • Export Citation
  • 4.

    Hunt GB, Johnson KA. Diaphragmatic hernias. In: Johnston SA, Tobias KM, Peck JN, Kent M, eds. Veterinary Surgery: Small Animal. 2nd Ed. Elsevier; 2018:15921603

    • Search Google Scholar
    • Export Citation
  • 5.

    Benitez Lazzarotto A, O’Rourke NA, Fitzgerald BT, Wong D, Scalia GM. Hernia of the diaphragmatic caval foramen causing right atrial “mass”, caval obstruction and pulmonary embolism. Int J Cardiol. 2016;207:215216. doi:10.1016/j.ijcard.2016.01.166

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    • Search Google Scholar
    • Export Citation
  • Figure 1

    Right lateral (A), left lateral (B), and ventrodorsal (C) thoracic radiographs from the referring veterinarian.

  • Figure 2

    Right lateral (A), left lateral (B), and ventrodorsal (C) thoracic radiographs from the referring veterinarian. The white arrow denotes the focal round to broad-based soft tissue structure noted by the radiologists.

  • Figure 3

    Individual images from the CT scan of the chest and abdomen in sagittal (A), transverse (B), and dorsal (C) reformats. The hernia is denoted in all images by a black asterisk. The caudal vena cava is denoted as CVC on images A and B. The left hepatic vein (LHV) and portal vein (PV) are visible in image C. The black arrow in image C points to a small venous branch from the central division that can be seen passing into the hernia.

  • Figure 4

    A still image captured during abdominal ultrasound. The hernia (HER) can be seen just cranial to the diaphragm denoted by a white arrow. The liver (LVR), heart (HRT), and caudal vena cava (CVC) are also visible.

  • 1.

    Kim J, Kim S, Jo J, Lee S, Eom K. Radiographic and computed tomographic features of caval foramen hernias of the liver in 7 dogs: mimicking lung nodules. J Vet Med Sci. 2016;78(11):16931697. doi:10.1292/jvms.16-0161

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2.

    Ng CS, Lee TW, Wan S, Yim AP. Caval foramen hernia masquerading as a thoracic mass. Can J Surg. 2006;49(1):6465.

  • 3.

    Park J, Lee HB, Jeong SM. Caval foramen hernia in a dog: preoperative diagnosis and surgical treatment. J Vet Med Sci. 2020;82(11):16021606. doi:10.1292/jvms.19-0575

    • Search Google Scholar
    • Export Citation
  • 4.

    Hunt GB, Johnson KA. Diaphragmatic hernias. In: Johnston SA, Tobias KM, Peck JN, Kent M, eds. Veterinary Surgery: Small Animal. 2nd Ed. Elsevier; 2018:15921603

    • Search Google Scholar
    • Export Citation
  • 5.

    Benitez Lazzarotto A, O’Rourke NA, Fitzgerald BT, Wong D, Scalia GM. Hernia of the diaphragmatic caval foramen causing right atrial “mass”, caval obstruction and pulmonary embolism. Int J Cardiol. 2016;207:215216. doi:10.1016/j.ijcard.2016.01.166

    • PubMed
    • Search Google Scholar
    • Export Citation

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