Endoscopic examination of the upper respiratory tract and oesophagus in small ruminants: Technique and normal appearance

Video Endoscopy-Guided Intrabronchial Spray Inoculation of Mycobacterium bovis in Goats and Comparative Assessment of Lung Lesions With Various Imaging Methods

Bovine tuberculosis (bTB) not only poses a zoonotic threat to humans but also has a significant economic impact on livestock production in many areas of the world. Effective vaccines for humans, livestock, and wildlife are highly desirable to control tuberculosis. Suitable large animal models are indispensable for meaningful assessment of vaccine candidates. Here, we describe the refinement of an animal model for bTB in goats. Intrabronchial inoculation procedure via video-guided endoscopy in anesthetized animals, collection of lungs after intratracheal fixation in situ, and imaging of lungs by computed tomography (CT) were established in three goats using barium sulfate as surrogate inoculum. For subsequent infection experiments, four goats were infected with 4.7 × 10² colony-forming units of M. bovis by intrabronchial inoculation using video-guided endoscopy with spray catheters. Defined amounts of inoculum were deposited at five sites per lung. Four age-matched goats were mock-inoculated. None of the goats developed clinical signs until they were euthanized 5 months post infection, but simultaneous skin testing confirmed bTB infection in all goats inoculated with M. bovis. In tissues collected at necropsy, M. bovis was consistently re-isolated from granulomas in lymph nodes, draining the lungs of all the goats infected with M. bovis. Further dissemination was observed in one goat only. Pulmonary lesions were quantified by CT and digital 2D radiography (DR). CT revealed mineralized lesions in all the infected goats ranging from <5 mm to >10 mm in diameter. Small lesions <5 mm predominated. The DR failed to detect small lesions and to determine the exact location of lesions because of overlapping of pulmonary lobes. Relative volume of pulmonary lesions was low in three but high in one goat that also had extensive cavitation. CT lesions could be correlated to gross pathologic findings and histologic granuloma types in representative pulmonary lobes. In conclusion, video-guided intrabronchial inoculation with spray catheters, mimicking the natural way of infection, resulted in pulmonary infection of goats with M. bovis. CT, but not DR, presented as a highly sensitive method to quantify the extent of pulmonary lesions. This goat model of TB may serve as a model for testing TB vaccine efficacy.

Surgical Training on Ex Vivo Ovine Model in Otolaryngology Head and Neck Surgery: A Comprehensive Review

Background: Nowadays, head and neck surgical approaches need an increased level of anatomical knowledge and practical skills; therefore, the related learning curve is both flat and long. On such procedures, surgeons must decrease operating time as much as possible to reduce the time of general anesthesia and related stress factors for patients. Consequently, little time can be dedicated for training skills of students and young residents in the operating theater. Fresh human cadavers offer the most obvious surrogate for living patients, but they have several limitations, such as cost, availability, and local regulations. Recently, the feasibility of using ex vivo animal models, in particular ovine ones, have been considered as high-fidelity alternatives to cadaveric specimens. Methods: This comprehensive review explores all of head and neck otolaryngology applications with this sample. We analyzed studies about ear surgery, orbital procedures, parotid gland and facial nerve reanimation, open laryngeal and tracheal surgery, microlaryngoscopy procedures, laryngotracheal stenosis treatment, and diagnostic/operative pediatric endoscopy. For each different procedure, we underline the main applications, similarities, and limitations to human procedures so as to improve the knowledge of this model as a useful tool for surgical training. Results: An ovine model is easily available and relatively inexpensive, it has no limitations associated with religious or animal ethical issues, and it is reliable for head and neck surgery due to similar consistencies tissues and neurovascular structures with respect to humans. However, some other issues should be considered, such as differences about some anatomical features, the risk of zoonotic diseases, and the absence of bleeding during training. Conclusion: This comprehensive review highlights the potentials of an ex vivo ovine model and aims to stimulate the scientific and academic community to further develop it for other applications in surgical education.

Ex vivo ovine model for pediatric flexible endoscopy training

OBJECTIVES

Medical students and residents in training have limited opportunities to develop pediatric endoscopy skills and would benefit from a realistic simulation model. We sought to develop such a model for flexible endoscopy using fresh head and neck tissue from young sheep.

METHODS

Tissue was collected from pre-pubescent sheep (n=5; mean age: 4 months; mean mass: 28kg) following humane euthanasia at the end of an in vivo protocol. No live animals were used in this study. The head and neck of the sheep were disarticulated 4-6cm above the sternal notch and stored at 5°C for 1-5 days. With the preparation was supported in supine position, flexible nasopharyngolaryngoscopy and transnasal endoscopic intubation were performed with video recording.

RESULTS

Five sheep were studied. Endoscopy was performed by a medical student under direct supervision by a pediatric otolaryngologist. Differences between ovine and human pediatric airway anatomy were defined.

CONCLUSIONS

Despite variations in proportion and structure, the experience of passing a flexible nasopharyngoscope through a sheep's airway is remarkably similar to pediatric endoscopy. The nasal anatomy is elongated, but very much like a child's in terms of anatomy, color and texture. The tactile feedback is nearly identical. Annoying secretions and their associated "whiteout" phenomena nicely simulate these challenges in pediatric endoscopy. When performing transnasal intubation, navigating to the larynx and advancing an endotracheal tube under guidance have the look and feel of the pediatric procedure. Issues of cost, availability, risk of zoonotic infection, and ethics are discussed.