5    Medical Thoracoscopy/Pleuroscopy in Animals

Thoracoscopy in animals relates to three different topics: use for diagnosis and treatment in animals, use for research in animals, and use for teaching of the technique.

Use for Diagnosis and Treatment in Animals

In veterinary medicine, thoracoscopy has been mainly applied in the horse, first for diagnostic purposes (Mackey and Wheat 1985; McCarthy 1990), but also for treatment, e.g., for drain placement in pleural effusions and abscesses, transection of pleural adhesions, and decortication as well as for window pericardectomy (Vachon and Fischer 1998). In an experimental study in six healthy, conscious horses, the pleuropulmonary and cardiovascular consequences of thoracoscopy were investigated and no detrimental effects or significant complications were found (Peroni et al. 2000). The advances in instrumentation enabled the use of video-assisted thoracic surgery in horses (Klohnen and Peroni 2000).

Thoracoscopy for evaluating the etiology of pleural effusions is used successfully in dogs and cats as well, and is seen as a less-invasive alternative to thoracotomy (Kovak et al. 2002).

Use for Research in Animals

Boutin and co-workers tested the technique of thoracoscopic lung biopsy (TLB) in 14 dogs using two entries, one for the telescope, and one for a coagulating forceps. TLB yielded a high rate of adequate samples (up to 5 mm × 5 mm × 5 mm) without major complications (Boutin et al. 1982). In the same article, they report on the subsequent application of TLB in 75 patients, with a high diagnostic yield and few minor complications.

Viallat and co-workers, using TLB with instruments adapted to the size of animals, investigated the bacteriological diagnostic yield in 84 immunosuppressed and/or infected NZ rabbits (Viallat et al. 1985). They compared the results with those of surgical biopsies made in the same animals, and found similar sensitivities of both methods (approx. 90% versus 100%).

Seitz and co-workers, again from Christian Boutin’s group in Marseille, performed an experimental study in dogs to test whether the instillation of a fibrin sealant (Tissucol) was effective in the treatment of pneumothorax. The result was negative since no pleurodesis was noted (Seitz et al. 1989).

Colt and co-workers compared the gross and histological findings of wedge lung biopsy to forceps video-thoracoscopic lung biopsy in five adult swine, using a 5-mm endoscopic cupped forceps. One hundred and thirteen forceps biopsy specimens and 24 sections from eight wedge biopsy specimens were examined. They detected no major differences in overall microscopic specimen quality (Colt et al. 1995).

In another animal study, Colt and co-workers compared thoracoscopic talc insufflation (poudrage), talc slurry, and mechanical abrasion in 10 dogs. Although differences were not statistically significant, thoracoscopic talc insufflation consistently produced the most widespread, firm fibrotic adhesions as evidenced by higher obliteration grades (Colt et al. 1997).

Another talc pleurodesis study was done in six young swine in which the effects on respiratory mechanics were measured (McGahren et al. 1990). The authors found that talc pleurodesis causes a temporary impairment in dynamic transpulmonary and transrespiratory compliance that resolves with time and growth. Several other studies on thoracoscopic talc pleurodesis were performed in dogs (Mathlouthi et al. 1992) and pigs (Cohen et al. 1996; Whitlow et al. 1996).

Use for Teaching of the Technique

A variety of animal models have been used in training courses along with didactic lectures including videos. The most common animal model is the goat or the pig. The animal is intubated with single-lumen tube ventilation and is then placed in the lateral decubitus position and allowed to breathe spontaneously, or occasionally has to be placed on a ventilator with low tidal volume. The pleural space is opened in standard manner as for medical thoracoscopy. The instruments are then placed in the chest for observation. The biopsies of the pleura are again done in a standard manner but are somewhat difficult because the pleura is normal and the forceps tend to slip. The biopsies have to be taken over the rib. The normal pleura allows visualization the rib and the neurovascular bundle during procedure, which is not the case in the human as the diseased pleura are thick and painless. Occasionally the procedure has to be stopped for ventilation of the animal as needed. The whole procedure should be done with a veterinarian responsible for the wall-being of the animal, and the procedure should have been approved by the institutional board. Proper animal care is essential and euthanasia should be performed in a standard manner as suggested by the veterinary services.

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