What is Mediastinal/Pleural Biopsy?
The pleura are the thin tissues lining the inner wall of the chest, covering the chest wall and internal thoracic organs, providing lubrication and aiding in fluid drainage within the chest. The mediastinum is the space created in the fold between the left and right pleura, and contains vital structures such as major nerves, blood vessels, the esophagus, and thymus. Biopsy of the pleura or mediastinum in dogs may be required in the investigation of suspected tumors, atypical infections, chylothorax, and occasionally autoimmune disease. However, an internal biopsy of this nature will normally only be performed when other diagnostic methods have failed to yield definitive findings. While pleural biopsy may be performed by veterinarians in general practice, mediastinal biopsy is usually more invasive, and will generally be performed by a specialist surgeon.
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Mediastinal/Pleural Biopsy Procedure in Dogs
Obtaining tissue samples in mediastinal or pleural biopsy requires the surgeon to enter the chest cavity, usually through an incision between ribs, although an approach through the breast bone may also be practised. This will of course require general anesthesia. Depending on the site to be sampled, the incision may be located anywhere along the ribcage, and may extend the entire height of the chest wall.
On entering the chest through this incision, a loss of negative pressure between the chest wall and pleural tissue leads to an influx of air, and pressure-induced collapse of the lungs. At this point, mechanically assisted ventilation will be initiated to maintain inflation of the lungs and blood oxygenation. The surgeon may then manipulate the internal organs as required to visualize the area of interest, at which point a tissue sample may be obtained, using a scalpel or other instrument to remove a representative tissue sample, which may then be submitted for laboratory testing. While there is always a risk that the procedure may prove to be non-diagnostic, most pleural biopsies should yield diagnostic information, particularly when a distinct lesion, such as a tumor or fungal plaque, is visible.
Having ensured that any bleeding from the biopsy site is under control, the veterinarian may then close the incision by sequentially suturing together the pleura, ribs, subcutaneous tissues, and skin. Local pain relief is usually provided by injecting local anesthetic drugs, and any remaining free air in the pleural space will be aspirated to allow the lungs to fully inflate. Ongoing monitoring will be usually be required for two to five days to ensure a smooth recovery.
Efficacy of Mediastinal/Pleural Biopsy in Dogs
Less invasive biopsy techniques may be employed where possible. Simple, ‘blind’ aspiration using a small-gauge needle can be performed in conscious dogs, and while it may not accurately target discrete lesions, can yield useful information in cases of infection or autoimmune disease. Alternatively, a veterinarian skilled in the use of diagnostic ultrasound may be able to visualize localized lesions and direct a needle or other biopsy instrument through the skin in order to obtain a biopsy sample. The latter option will normally require sedation to accurately guide the biopsy path.
Mediastinal/Pleural Biopsy Recovery in Dogs
On discharge from the hospital, the patient will need to refrain from strenuous exercise for two to three weeks and will be provided with painkillers in the form of oral, dermal, or injectable medication. It may be necessary to visit the veterinarian for dressing changes several times following discharge.
Cost of Mediastinal/Pleural Biopsy in Dogs
Due to its nature as a technically demanding, specialist procedure, the costs associated with mediastinal/pleural biopsy can be significant, likely running to several thousand dollars. Prior to surgery, the patient is likely to undergo X-ray and CT scans, which will cost in the region of $1,000. Other preoperative assessments including blood and urine tests may cost a further $300, while the surgery, pathology exams, and postoperative care usually cost upwards of $2,000. As this is a major surgical intervention, care must be tailored to individual patients, and intensive care requirements may increase the prices stated here.
Dog Mediastinal/Pleural Biopsy Considerations
Mediastinal/pleural biopsy provides a means of definitively diagnosing a range of serious conditions, and may facilitate successful treatment and cure of the underlying condition. As a diagnostic, rather than therapeutic intervention, it should be performed where other, less invasive investigations have been unrewarding. Risks include intraoperative bleeding and respiratory or cardiac complications. Postoperative infections or lung collapse are uncommon, particularly with careful nursing care.
Mediastinal/Pleural Biopsy Prevention in Dogs
There is little an owner can do to prevent their dog developing any of the conditions investigated using mediastinal/pleural biopsy. Dogs with pleural or mediastinal lesions may show signs of chest pain, weight loss, and cough, and owners should be vigilant to these signs and present the pet to their veterinarian at the earliest possible stage of illness.