Summary Reasons for performing study and objective: To review the prevalence of single and complex forms of dynamic airway obstructions within a large group of Thoroughbred horses in training referred for investigation of poor performance. Methods: Video‐endoscopic recordings of the upper respiratory tract made during a standardised treadmill exercise test of 600 Thoroughbred racehorses were reviewed and analysed in real time and slow motion to identify dynamic collapse by the tissues bordering onto the pharyngeal and laryngeal airways. Results: Dynamic collapse within the nasopharynx or larynx was confirmed in 471 of the 600 horses. Dorsal displacement of the soft palate (DDSP; 50%) and palatal instability (33%) were the disorders most frequently identified. It was concluded that deglutition is not a significant event in the triggering of DDSP. Complex forms of dynamic collapse were present in 30% of the horses with upper respiratory tract obstructions. A significant influence of age on the prevalence of DDSP and dynamic laryngeal collapse was identified. There was an increased risk of DDSP in younger horses, and of laryngeal collapse in older horses. No association with gender or format of racing was identified. Conclusions and potential relevance: Palatal instability and DDSP comprised the most frequently encountered forms of dynamic collapse within the upper respiratory tract of the Thoroughbred racehorses in this study and are probably expressions of the same nasopharyngeal malfunction. Complex obstructions, i.e. where more than one structure collapses into the airway, occur frequently and therefore treatments that address solitary disorders may often be unsuccessful. Younger horses were found to be at greater risk of sustaining DDSP while older horses seemed more at risk to vocal cord collapse but not to collapse of the arytenoid cartilage itself.

Summary The clinical records of 100 cases of headshaking in horses were reviewed. Possible causes of the abnormal behaviour were identified in 11 animals; these included ear mite infestation, otitis interna, cranial nerve dysfunction, cervical injury, ocular disease, guttural pouch mycosis, dental periapical osteitis and suspected vasomotor rhinitis. However, in only two of these could it be shown that correction of the abnormality led to elimination of the headshaking. The additional clinical signs exhibited by the other idiopathic cases of headshaking included evidence of nasal irritation, sneezing and snorting, nasal discharge, coughing and excessive lacrimation. Many of these horses also showed a marked seasonal pattern with respect to the onset of the disease and the recurrence of signs in subsequent years. The clinical presentation of idiopathic headshakers and the seasonal incidence of the signs closely resemble allergic rhinitis in man.

Summary Reasons for performing study: The reliability of diagnoses of obstructive conditions of the upper respiratory tract (URT) based on examinations performed at rest vs. at exercise is controversial. Objective: To compare diagnosis of URT by endoscopy at rest with that achieved during high‐speed treadmill exercise (HSTE). Hypothesis: Endoscopy of URT at rest, when performed in isolation from other simpler techniques is unreliable in the prediction of dynamic respiratory obstructions. Methods: Endoscopic findings of 600 Thoroughbred racehorses during quiet breathing were compared with findings during high‐speed treadmill exercise. Other parameters were also assessed for their specificity in diagnosis. Results: Endoscopy of the resting horse showed low sensitivity (0.15) in the diagnosis of dorsal displacement of the soft palate (DDSP) and palatal instability (PI). When endoscopy and reported noises were taken together there was still a 35% misdiagnosis rate. Although there was significant association between resting laryngeal function score (LFS) and dynamic vocal cord and/or arytenoid cartilage collapse at exercise, 19% of horses with a grade 4/5 LFS were able to attain and maintain full abduction during exercise and 7% of those with ‘normal’grades 1 or 2 LFS at rest showed dynamic laryngeal collapse when exerted. Sensitivity of the diagnostic model was greatly increased (80%) when a history of inspiratory noise and palpable intrinsic muscle atrophy were included. Conclusions and potential relevance: Endoscopy of the upper respiratory tract of static horses is unreliable in the diagnosis of dynamic obstructions of the URT and should not be used in isolation in surgical decision‐making or in the assessment of horses at the time of sale.

Summary The radiographic findings in 167 horses subjected to radiography of the facial area, nasal cavity and paranasal sinuses are recorded. Cases were grouped according to clinical diagnosis and the common and disparate radiographic features between and within groups are discussed. Dental disease occurred most frequently and accounted for about 30 per cent of cases, most of which had periapical infection. This disorder presented as two distinct clinical entities in almost equal numbers affected teeth with roots rostral to the maxillary sinus usually produced facial swelling, whereas those with roots within the sinus were generally associated with nasal discharge as a result of secondary sinusitis. In the former group periapical changes could readily be identified on radiographs, but in the latter group affected teeth could be recognised with confidence in only about half the cases. Primary sinusitis was the commonest specific condition recorded and accounted for 32 cases, three of which were mycotic. Using lateral erect projections, comparison of the radiographic features of primary sinusitis and sinusitis secondary to dental disease showed some useful differentiating signs. In four ponies, rhinitis associated with sinusitis led to disruption of the intra‐nasal structures but mycotic rhinitis, nasal ulceration and an intra‐nasal foreign body produced no radiographic abnormalities. Sixteen cases of suture periostitis were recorded, with varying degrees of new bone formation, and of 13 animals presented for evaluation of trauma, pre‐diagnosed fractures were demonstrated in 10 and complications due to sinusitis in three. Twelve cases of paranasal sinus cysts and three of 10 progressive ethmoidal haematomas showed non‐specific radiographic changes within the spectrum of those recorded in sinusitis, while the remaining ethmoidal haematomas produced distinctive clearly defined opacities, four of which were within paranasal sinuses. Four tumours were confirmed histologically, but other neoplastic lesions are probably also included in a group of 10 cases of undiagnosed cysts or masses. Other conditions, which occurred sporadically, are of anecdotal interest only. The incidence of wolf teeth among a group of 134 horses was 33 per cent.

Sixty‐five dogs were examined and treated for stick penetration wounds of the pharynx. Dysphagia, pain, pyrexia and local cellulitis were common presenting signs amongst recently injured dogs. Injuries involving the oesophagus resulted in subcutaneous emphysema and dyspnoea associated with pneumomediastinum. Longstanding wounds presented with discharging sinuses of the head, neck or cranial thoracic region. Wooden foreign bodies were recovered from 37 dogs (57 per cent) with subsequent resolution of their clinical signs. No foreign body was retrieved from a further 18 dogs (28 per cent) but their clinical signs resolved after appropriate wound management. Four dogs (6 per cent) died shortly after the injury from major oesophageal tears which allowed mediastinal contamination. Six dogs (9 per cent) had no foreign body recovered at surgery and the discharging sinuses persisthed. The need for vigorous management of the fresh injury in order to preclude the development of chronic complications is emphasised.