Ultrasound-guided arthrocentesis of the temporomandibular joint in healthy adult horses is equivalent to blind arthrocentesis.

Equine temporomandibular joint (TMJ) diseases are increasingly recognized as a problem for the well-being and performance of horses. Diagnosis is confounded by overlap of clinical signs associated with pathology of the oral cavity, poll, and cervical vertebrae. Arthrocentesis for intra-articular analgesia, sampling of synovial fluid, and medication is needed for diagnostic and therapeutic purposes. Ultrasound features of the normal TMJ and a blind arthrocentesis technique have been described, but a systematic approach to ultrasound-guided (USG) arthrocentesis has not been reported. Ultrasound guidance allows visualization of the TMJ that may prove beneficial in cases when pathology, abnormal anatomy, or clinician inexperience make blind arthrocentesis difficult. We hypothesized that USG arthrocentesis would result in fewer needle repositions than blind arthrocentesis. We also aimed to assess synovial fluid parameters for normal equine TMJs. A prospective randomized method comparison with crossover experimental design compared the number of needle positionings required for accurate injection of the TMJ using each technique. Arthrocentesis technique and operator experience were tested using cadavers and two operators. Injection success was confirmed using CT. The radiologist then applied both techniques in normal live horses. No statistically significant difference was noted between arthrocentesis techniques or operators (P > .05). No complications were observed in live horses following either technique. Synovial fluid parameters were largely within the normal range expected for other synovial joints. Either blind or USG arthrocentesis of the equine TMJ can be performed with minimal prior operator experience. Ultrasound-guided arthrocentesis is an alternative method and can be considered in cases with altered anatomy.

Retrograde intubation in a dog with severe temporomandibular joint ankylosis: case report.

BACKGROUND: Orotracheal intubation in dogs is a common and easily-performed procedure that provides a patent airway during anaesthesia. In dogs with temporomandibular joint ankylosis or pseudo-ankylosis, airway management can be a challenging procedure since these dogs have a limited ability to open their mouth. Methods to provide safe, uneventful intubation in such patients may include minimally invasive techniques such as retrograde intubation using a guide wire and fibre-optic-aided laryngoscopy. CASE PRESENTATION: We report a case of a 16-month-old, intact female Bull Terrier weighing 17 kg, admitted to the hospital for surgical treatment of bilateral ankylosis of the temporomandibular joint. Intubation was achieved, without direct observation of the larynx, by retrograde intubation using a vascular access catheter and a vascular wire guide through cricothyroid membrane. Bilateral condylectomy was performed and the dog recovered uneventfully. CONCLUSIONS: In conclusion, retrograde intubation was relatively simple to perform with the guide wire technique and no specific training or equipment were necessary.

Osteoarthritis of the temporomandibular joint in the Eastern Atlantic harbour seal (Phoca vitulina vitulina) from the German North Sea: a study of the lesions seen in dry bone.

BACKGROUND: Pathological changes and resulting functional impairment of the temporomandibular joint (TMJ) can substantially affect physical condition, morbidity, and mortality of wildlife species. Analysis of TMJ disorders is therefore of interest for the characterization of the health status of populations of wild mammals. This paper, for the first time, analyses the prevalence of TMJ osteoarthritis (TMJ-OA) and the spectrum of osteoarthritic bone lesions of the TMJ in the Eastern Atlantic harbour seal (Phoca vitulina vitulina), applying a standardized scoring system. Dry skulls of 1872 individuals from the German North Sea, collected between 1961 and 1994, were examined for lesions consistent with a diagnosis of TMJ-OA. Of the skulls, 913 (48.8%) were from male, 959 (51.2%) from female seals, with age at death ranging from 2 weeks to 25 years. Possible associations of TMJ-OA with dental or periodontal disorders were also analysed. RESULTS: Lesions consistent with TMJ-OA were found in 963 (53.9%) of the 1787 juvenile/subadult (5 weeks to 5 years of age) and adult (> 5 years) specimens, the condition mostly (95.0% of affected individuals) occurring in a bilateral fashion. Males were affected more frequently than females (p < 0.001), while lesion severity tended to be higher in females (p < 0.05). Severity of TMJ-OA lesions was positively correlated with age (p < 0.001). Lesion severity was also weakly positively correlated with the number of fractured teeth (p < 0.05) and of intravitally lost teeth (p < 0.01), when controlling for age at death as a confounder. CONCLUSIONS: TMJ-OA is a common disorder in the Eastern Atlantic harbour seal. The more pronounced severity of the lesions in females compared to males is basically attributed to the higher average age of the female subsample. The causes underlying the high prevalence of TMJ-OA in the studied assemblage remain unknown. Most of the specimens (75.3%) analysed in the present study were found dead during the first phocine distemper virus epizootic in 1988. Therefore, it is assumed that, contrary to other museum collections, only little overrepresentation of pathological skeletal conditions is present in this death sample compared with the population from which it originated.

Ultrasonographic imaging of the temporomandibular joint in healthy cattle and pathological findings in one clinical case.

AIMS: To describe the normal ultrasonographic appearance of the temporomandibular joint (TMJ) in cattle, and to describe the ultrasonographic pathology of the TMJ as assessed in one cow with TMJ disease. METHODS: The TMJ of 12 healthy Holstein-Friesian cows were examined using a portable ultrasonographic unit with a 7.5 MHz linear probe and a 6.0 MHz convex probe. Each TMJ was scanned in a rostrolateral, lateral and caudolateral plane. In addition, the TMJ of one 2-year-old cow with clinical signs of food retention in the mouth, head tilt, swelling and pain in the right TMJ region and an infected horn fracture was examined ultrasonographically. RESULTS: The bone surfaces of the temporal process, the zygomatic process and the temporal bone, the larger muscles of the TMJ region, the superficial temporal vein, and the parotid salivary gland could be imaged in all normal healthy cattle. Using the linear probe, the joint capsule was visible in 17/24 (71%) cases in the caudolateral plane, but the articular disc could not be visualised. With the convex probe, the joint capsule could be imaged in all cases in the caudolateral plane, and the articular disc in 13/24 (54%) cases in the caudolateral plane. It was never possible to see the synovial pouch in healthy cattle using either probe. By contrast, in the cow diagnosed with septic arthritis of the right TMJ, a marked anechoic and heterogeneous hypoechoic effusion of the TMJ with distension of the joint capsule was visualised. CONCLUSIONS: The results of this descriptive study serve to provide a reference for ultrasonography of pathological conditions of the TMJ region in cattle. CLINICAL RELEVANCE: As many veterinarians are equipped with ultrasound machines with 5-8 MHz linear rectal probes, the authors recommend using these probes for further investigation of clinical cases with swelling of the TMJ region and/or masticatory problems of unclear origin to exclude or diagnose TMJ disorders.

Modified Labial Button Technique for Maintaining Occlusion After Caudal Mandibular Fracture/Temporomandibular Joint Luxation in the Cat.

Maxillofacial trauma in cats often results in mandibular symphyseal separation in addition to injuries of the caudal mandible and/or temporomandibular joint (TMJ). Caudal mandibular and TMJ injuries are difficult to access and stabilize using direct fixation techniques, thus indirect fixation is commonly employed. The immediate goals of fixation include stabilization for return to normal occlusion and function with the long-term objective of bony union. Indirect fixation techniques commonly used for stabilization of caudal mandibular and temporomandibular joint fracture/luxation include maxillomandibular fixation (MMF) with acrylic composite, interarcade wiring, tape muzzles, and the bignathic encircling and retaining device (BEARD) technique. This article introduces a modification of the previously described "labial reverse suture through buttons" technique used by Koestlin et al and the "labial locking with buttons" technique by Rocha et al. In cases with minimally displaced subcondylar and pericondylar fractures without joint involvement, the labial button technique can provide sufficient stabilization for healing. Advantages of the modified labial button technique include ease of application, noninvasive nature, and use of readily available materials. The construct can remain in place for a variable of amount of time, depending on its intended purpose. It serves as an alternative to the tape muzzle, which is rarely tolerated by cats. This technique can be easily used in conjunction with other maxillomandibular repairs, such as cerclage wire fixation of mandibular symphyseal separation. The purpose of this article is to demonstrate a modified labial button technique for maintaining occlusion of feline caudal mandibular fractures/TMJ luxations in a step-by-step fashion.

Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography.

The temporomandibular joint (TMJ) in the domestic dog is a synovial joint with 2 articular surfaces, the mandibular fossa of the squamous portion of the temporal bone and the articular head of the condylar process of the mandible. Although different diagnostic imaging techniques have been used to study the TMJ in dogs, morphologic and morphometric studies based on computed tomography (CT) are scarce. The purpose of the present study was to describe the morphologic and morphometric features of the TMJ in domestic dogs using CT. Width and depth of the mandibular fossa and 2 different angles between the mandibular fossa and the condylar process were measured in 96 TMJs of 48 dogs of different breeds (Labrador retriever, German shepherd, cocker spaniel, boxer, English bulldog, pug, shih tzu, and Cavalier King Charles spaniel). Temporomandibular joint conformation differed between breeds. Mid- and small-sized dogs had mandibular fossae that were more shallow, less developed retroarticular processes, and irregularly shaped condylar processes. The TMJs were more congruent in large dogs, presenting with deeper mandibular fossae, prominent retroarticular processes, and more uniform condylar processes. The measurements proposed in this study demonstrated 3 different morphologic conformations for the TMJ in the dogs of this study.

Imaging diagnosis--temporomandibular joint dysplasia in a Basset Hound.

A 5-month-old intact male Basset Hound presented for evaluation of pain and crepitation during manipulation of the temporomandibular joint, worse on the right side. A computed tomography (CT) scan of the head was performed. The CT images demonstrated the osseous features of temporomandibular joint dysplasia and facilitated a 3D reconstruction, which allowed better visualization of the dysplastic features. The patient responded to conservative management with a tape muzzle with no recurrence reported by the owner 6 months after presentation.

Temporomandibular Joint Gape Angles in Normal and Painful Domestic Felines.

The purpose of this study was to determine and compare the gape angles (temporomandibular joint range of motion with mouth opening) of conscious and anesthetized domestic felines and to compare gape angles with and without evidence of oral pain. This prospective study evaluated the gape angle of 58 domestic felines. The cats were grouped into painful (n = 33) and nonpainful cohorts (n = 25) and gape angles were compared during conscious and anesthetized conditions. Gape angles were determined based on measurements of the maximal interincisal distance and lengths of the mandible and maxilla followed by calculation of the law of cosines. The mean feline gape angle (standard deviation) was determined to be 45.3° (8.6°) and 50.8° (6.2°) for conscious and anesthetized felines respectively. There was no significant difference between painful and non-painful feline gape angles during conscious (P = .613) or anesthetized (P = .605) evaluations. There was a significant difference between anesthetized and conscious gape angles (P < .001) for both painful and non-painful cohorts. This study determined the standardized, normal feline temporomandibular joint (TMJ) gape angle in both conscious and anesthetized states. This study suggests that the feline gape angle is not a useful indicator of oral pain. By determining the feline gape angle, which was previously unknown, further evaluation of its utility as a non-invasive clinical parameter for evaluation of restrictive TMJ motions as well as its use for serial evaluations may be pursued.

Equine poor performance: the logical, progressive, diagnostic approach to determining the role of the temporomandibular joint.

Poor performance is an ambiguous term used frequently by people in the horse industry. It means different things to different people, depending on the breed, discipline, or problem being discussed. There are myriad reasons that a horse may fail to achieve the expectations put upon it or, having achieved those goals, begin to falter. Equine temporomandibular joint (TMJ) disease is beginning to be reported as 1 such cause of poor performance. Despite this, in certain disciplines, it has become the trendy diagnosis, and a logical approach to the diagnostic workup is often lacking. Many of the clinical signs attributed to TMJ abnormalities can be readily explained by other more common problems. This ambiguity is compounded by a lack of extensive scientific evidence linking TMJ-related disease to behavioral or performance changes. Despite this fact, the equine TMJ has been reported to be a cause of poor performance, and while rare, it should be included in a differential diagnosis list, albeit one of exclusion. The purpose of this article is to describe a logical, stepwise approach to excluding common causes of poor performance before investigating the potential role of the TMJ in cases of poor performance.

Kinematic performance of a novel temporomandibular joint replacement prosthesis under bite-force conditions in dogs and cats.

OBJECTIVE: To evaluate the kinematics and stability of the temporomandibular joint (TMJ) of cats and dogs with and without a TMJ replacement (TMJR) prosthesis under simulated bite forces and mouth opening. ANIMALS: Sixteen cadaver skulls from domestic cats (n = 8) and medium- to large-breed dogs (n = 8). METHODS: Intact TMJs were tested. Following condylectomy and coronoidectomy, the skulls were fitted with a TMJR prosthesis unilaterally and retested. Prosthesis was similarly implanted in the contralateral TMJ in 4 cats and 4 dogs before retesting. Left and right bite motions were evaluated before bite contact to peak bite force (200 N in dogs, 63 N in cats). Mouth opening motion was recorded. Mandibular displacement under load was evaluated in 3 orthogonal planes. Maximal displacement was compared between TMJR groups and native TMJ. Prosthesis-bone motion of the temporal and mandibular components was evaluated during simulated bites and mouth opening. RESULTS: TMJR resulted in joint motion not demonstrably different from the native TMJ, with the ability to fully open and close the mouth and with minimal laterotrusion. The TMJR prosthesis demonstrated similar stability after unilateral and bilateral replacement during bite force and with an open mouth. Mean implant-bone motion during bite simulations for the temporal and mandibular TMJR components was ≤ 60 µm in cats and ≤ 30 µm in dogs. CLINICAL RELEVANCE: A novel TMJR can be implanted and allows normal jaw motion. Joint stability is maintained after TMJR implantation in the TMJ of dogs and cats TMJ that is devoid of muscular support.

Otitis interna, media, and externa with destruction of the left tympanic bulla and subluxation and septic arthritis of the left temporomandibular joint in an alpaca (Vicugna pacos).

A 1.5-year-old, 37.7 kg, female alpaca was evaluated for a 2-week history of weight loss, left ear droop, and deviation of the rostral mandible to the right. Antemortem radiography and postmortem examination revealed otitis interna, media, and externa, destruction of the left tympanic bulla, and subluxation and septic arthritis of the left temporomandibular joint.

Otite interne, moyenne et externe avec destruction de la bulle tympanique gauche et subluxation et arthrite septique de l'articulation temporomandibulaire gauche chez un alpaga(Vicugna pacos) . Une femelle alpaga âgée de 1,5 an, pesant 37,7 kg, a été évaluée pour une anamnèse de 2 semaines de perte de poids, d'oreille gauche pendante et de déviation de la mandibule rostrale à la droite. Une radiographie avant le décès et une nécropsie ont révélé une otite interne, moyenne et externe, la destruction de la bulle tympanique gauche ainsi qu'une subluxation et l'arthrite septique de l'articulation temporomandibulaire gauche.(Traduit par Isabelle Vallières).

Dental and temporomandibular joint pathology of the island fox (Urocyon littoralis).

Museum skull specimens from 318 island foxes (Urocyon littoralis) were examined macroscopically according to predefined criteria. The study population included males (n = 129, 40.6%), females (n = 93, 29.3%) and animals of unknown sex (n = 96, 30.2%), and comprised 182 (57.2%) adults, 118 (37.1%) young adults and 18 (5.7%) individuals of unknown age, with juveniles and neonates excluded. The number of teeth present for examination was 11,438 (85.6%) with 1918 (14.4%) absent artefactually, 4 (0.03%) absent congenitally and 243 (1.82%) lost ante mortem through acquired tooth loss. There were seven persistent deciduous teeth (0.05%) in three specimens and 11 supernumerary teeth (0.08%) in 10 specimens. Teeth with extra roots were found in 38 skulls (11.9%) with 0.48% of all teeth affected. Two (0.63%) specimens had one tooth with an abnormal form. Fifty-eight (18.2%) specimens had bone fenestrations. Of the alveoli examined, 5361 (46.9%) displayed bony changes suggestive of periodontitis, with 315 (99.1%) of skulls affected. Of the teeth available for examination in 310 specimens (97.5%), most (n = 6,040, 52.8%) had some degree of attrition or abrasion. Fractures affected 1217 (11.0%) of the teeth present in 266 specimens (83.6%). Twenty-three periapical lesions (0.20%) were present in 16 skulls (5.03%). Evidence of temporomandibular joint osteoarthritis was found in seven specimens (0.02%) on either the mandibular head of the condylar process or on the mandibular fossa of the temporal bone.

Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study.

The articular surfaces of the temporomandibular joint (TMJ) in the cat consist of the articular head of the condylar process of the ramus of the mandible and the mandibular fossa of the petrous part of the temporal bone. Anatomic conformation of the TMJ articular surfaces can vary; however, this has not been studied in the cat. Thus, the aim of this study was to characterize the conformation of the medial region of the TMJ in mesocephalic adult cats as well as to determine the articular relationship by measurement of the degree of coverage of the mandibular fossa over the articular head. This was accomplished by assessing 60 TMJs from 30 mesocephalic adult cats by means of cone-beam computed tomography (CBCT). The width and depth of the mandibular fossa, and the degree of coverage of the mandibular fossa were evaluated using parasagittal reconstructions of the medial aspect of the TMJ by two observers. No statistically significant difference was observed during the intra and interobserver evaluation of the mandibular fossa width and depth and the degree of coverage of the mandibular fossa over the articular head. P-values for the studied variables were greater than 0.05. The resulting measurements demonstrated a concave mandibular fossa with a prominent retroarticular process and a poorly developed articular eminence; a well-defined rounded articular surface, and a high degree of coverage (171°) of the mandibular fossa over the articular head. In conclusion, the articular surfaces at the medial aspect of the TMJ displayed elevated geometric similarity, with an articular head of the condylar process deeply seated in the mandibular fossa.

Dental and temporomandibular joint pathology of the Arctic fox (Vulpeslagopus).

Museum skull specimens from 224 Arctic foxes (Vulpes lagopus) were examined macroscopically using an established protocol for examination of mammalian skull specimens. Foxes were collected from coastal and island regions of Alaska, USA, except for two individuals. Collection years ranged from 1931 to 2016 with most specimens collected during the 1950s and 1960s. The study population comprised more females (n = 134, 59.8%) than males (n = 83, 37.0%) and individuals of unknown sex (n = 7, 3.1%). There were 108 (48.2%) young adults, 115 (51.3%) adults, and one (0.4%) individual of unknown age. A total of 8,891 teeth (94.5%) were available for examination. The most common types of pathology observed were periodontitis (n = 222, 99.1%), dental fractures (n = 175, 78.1%) and attrition/abrasion (n = 198, 88.4%). Periapical lesions (n = 12, 5.3%), temporomandibular joint (TMJ) osteoarthritis (n = 3, 1.3%) and root number variation (n = 5, 2.2%) were less common. Enamel hypoplasia was noted in eight foxes (3.6%), all of which were discovered on St. Matthew Island, Alaska, in 1963. As in other canid species, periodontitis, attrition/abrasion and tooth fractures are common in the Arctic fox, while TMJ pathology is rare. Loss of tooth crown substance probably reflects the influence of diet, interspecific and conspecific aggression and oral trauma due to trapping and hunting methods. The high prevalence of periodontitis is probably also due to the combined effects of diet, genetics and host immune reaction to oral bacteria.

Contemporary management of temporomandibular joint fractures in dogs and cats: review and expert insights on diagnostic imaging, treatment strategies, and long-term outcomes.

Management of temporomandibular joint (TMJ) fractures is challenging and is a subject of ongoing discussions and controversies in both the veterinary and human medical fields. Regardless of the management strategy, obtaining precise diagnostic imaging in the form of conventional or cone-beam computed tomography and potentially magnetic resonance imaging is pivotal for medical and surgical decision-making and prognostic purposes. The main objective of TMJ fracture management is a rapid return to normal function via restoration of pretrauma occlusion, range of motion, and masticatory function. With that in mind, it is prudent to distinguish between surgical interventions, such as condylectomy and open reduction with internal fixation, or to elect a conservative management approach. Given the diversity in TMJ fracture and patient circumstances, such as age, concomitant trauma, financial situation, and availability of expertise, the formulation of an individualized treatment plan is recommended. Knowledge of potential short- and long-term complications such as infection, malocclusion, ankylosis, fibrosis, and osteoarthritis is essential during TMJ fracture management. Importantly, as our clinical and research knowledge on managing TMJ fractures in dogs and cats grows, we rely on comparative evidence-based overviews, and inspirations from human medical experts to advance the veterinary field. Hence, this review discusses contemporary approaches to managing TMJ fractures and the outcomes in dogs and cats from a one-health perspective.

Dental and Temporomandibular Joint Pathology of the Steller Sea Lion (Eumetopias jubatus).

Skulls from 112 Steller sea lions (Eumetopias jubatus) were examined according to predefined criteria. Of the specimens, 73 (65.2%) were from males, 29 (25.9%) from females and 10 (8.9%) were of unknown sex, with 50 adults (44.6%), 61 young adults (54.5%) and one of unknown age (0.9%). The number of teeth evaluated was 3,521. Adults had more acquired tooth loss than young adults (P <0.0001). A total of 1,660 teeth (47.1%) from 111 specimens (99.1%) had evidence of attrition or abrasion. Adults displayed more attrition or abrasion than young adults (P <0.0001). A total of 241 teeth (6.8%) from 47 specimens (42%) had tooth fractures. Adults had more fractured teeth than young adults (P <0.0001). Bony changes consistent with periodontitis affected 36.7% of teeth. Adults had more teeth affected by periodontitis than young adults (P <0.0001). Temporomandibular joint osteoarthritis lesions were found in 54 specimens (48.2%) with more in adults than in young adults (P <0.0001). Although the significance of our findings is unknown, the occurrence and severity of these lesions may play an important role in the morbidity and mortality of Steller sea lions.

Computed tomographic features of the temporomandibular joint in 10 Jeju horses.

BACKGROUND: The equine temporomandibular joint (TMJ) has a complex anatomical structure that makes diagnosis of TMJ disorders difficult. Computed tomography (CT) is now available in equine medicine; hence, TMJ evaluation has become more convenient. OBJECTIVES: The objectives of this study were to describe the CT features of the TMJ in Jeju horses and to compare these features with those of Thoroughbreds. METHODS: In this report, the TMJs of 10 Jeju horses (mean age: 4.5 ± 1.9 yr; mean body weight: 282.6 ± 40.3 kg) and 6 Thoroughbreds (mean age: 7.3 ± 1.6 yr; mean body weight: 479.7 ± 44.0 kg) were examined using CT. After CT scanning, the Hounsfield units (HU) and height to width ratio (H:W) of the mandibular condyle were measured. RESULTS: The mean H:W in Jeju horses was significantly lower than that in Thoroughbreds. The mean HU in Jeju horses was lower than that in Thoroughbreds; however, the difference was not significant. The most frequent CT finding was an irregular medial margin of the mandibular condyle in both breeds. CONCLUSIONS: In this study, the shape of the mandibular condyle in Jeju horses was flatter than that in Thoroughbreds. This report could be useful in evaluating the TMJ in Jeju horses. Moreover, CT could be a pragmatic choice for the examination of the TMJ in horses.

Modified retrograde intubation through the cricothyroid membrane in a cat with temporomandibular joint ankylosis.

A 6-month-old, 2.9-kg, male, Korean short hair cat was referred for inadequate mouth opening (4 mm), and condylectomy was scheduled for ankylosis of the left temporomandibular joint. Retrograde intubation via the cricothyroid membrane was planned since direct visualisation of the larynx was not possible. In dorsal recumbency, the cricothyroid membrane was punctured with an 18-gauge needle, and a J-tip guidewire, inserted via the needle, was advanced and identified at the mouth. A 6-Fr truncated feeding tube was inserted from the mouth to the cricothyroid membrane along the guidewire. The guidewire was removed, and the tip of the feeding tube was advanced as an anterograde guide to the inner trachea. Subsequently, an endotracheal tube was inserted along the feeding tube. Capnography was used to confirm correct intubation. Condylectomy was performed on the left temporomandibular joint, and the patient recovered from anaesthesia uneventfully. Retrograde intubation is less invasive than tracheostomy or cricothyroidotomy, and the cricothyroid membrane has been suggested as a suitable site for guidewire insertion in humans and dogs. However, when resistance is encountered during the advancement of endotracheal tube using the traditional technique without the anterograde guide, it may be difficult to distinguish where the resistance occurred leading to damage or oesophageal displacement in cats with relatively fragile airway. This report suggests that retrograde intubation via the cricothyroid membrane can be performed in cats with limited visualisation of the larynx, and an anterograde guide following the retrograde wire could reduce the potential damage or oesophageal displacement.

Gape Angle in Asymptomatic Dogs with Normal Occlusion.

This study reports the gape angle (vertical temporomandibular joint range of motion for mouth opening) in conscious and anesthetized dogs. Mouth opening was reported as an angle in this study. Additionally, conscious and anesthetized measurements were compared to see if the state of anesthesia affected this measurement in asymptomatic patients. This prospective study evaluated 165 anesthetized dogs. Patients were placed in 1 of 2 groups: dental patients or non-dental patients. Only patients who were reported by owners to be asymptomatic for oral pain were included in the study. All dogs that met inclusion criteria had the maxillary length and interincisal distance measured. There was no difference (p = 0.590) between the mean (+/-SD) gape angle of conscious 44.0o (+/- 4.1+o) and anesthetized patients 43.9o (+/- 3.9o). No difference was seen in the gape angle between dental (44.2o) and non-dental patients (43.2o) (p = 0.183), or between conscious (43.8o) and anesthetized patients (43.7o) (p = 0.610). This study suggests that a consistent gape angle of 44o exists in dogs not exhibiting overt signs of oral pain and the gape angle is easy to measure in conscious patients and may be a useful tool during routine physical examination to identify patients with restricted range of motion. Immediate clinical application of this information can be used to monitor progress of treated patients affected by disorders that cause a decreased gape angle.