Temporo-mandibular joint dysplasia and open-mouth jaw locking in a Bassett Hound: a case report

A case of temporo-mandibular joint dysplasia with open-mouth jaw locking is described with reference to diagnosis and surgical treatment. Previous cases reported in the literature are reviewed.     

Intermittent open-mouth lower jaw locking in five dogs

Intermittent open-mouth lower jaw locking was documented in 5 dogs. In contrast to what has been reported in other cases, pronounced radiographic abnormalities in the temporomandibular joints were not observed. In 4 of the dogs, locking episodes started at a later age (35 to 83.5 months) than had been reported by others (6 to 22 months). Duration and frequency of locking were variable. Lateral shifting of the jaw and lack of neurologic deficits indicated a temporomandibular joint abnormality. Excision of the rostroventral portion of the involved zygomatic arch prevented locking in all cases. This syndrome involves variable severity of temporomandibular joint dysplasia, which could account for the variable age of onset and random frequency of locking episodes.     

Temporomandibular joint dysplasia in an Irish Setter

Dysplasia of the temporomandibular joints was diagnosed in an Irish Setter. The condyloid process was mis-shapen and the glenoid fossa flattened, which allowed subluxation of the temporomandibular joints with recurrent locking of the coronoid process on the zygomatic arch with the mouth open. Permanent relief from open mouth jaw locking was given by partial zygomatic arch ostectomy.     

Use of three-dimensional computed tomography for diagnosis and treatment planning for open-mouth jaw locking in a cat

CASE DESCRIPTION: A 2.5-year-old spayed female Persian cat was evaluated for acute inability to close its mouth. CLINICAL FINDINGS: A wry-mouth malocclusion was evident, and the right side of the mandible was longer than the left side. The right mandibular tooth row appeared to be lowered. The lower jaw was persistently maintained in an open position. The presumptive diagnosis was open-mouth jaw locking. Diagnostic imaging with computed tomography and 3-dimensional reconstruction was performed for definitive diagnosis and to achieve a better understanding of the lesions. Imaging revealed locking of the right ramus of the mandible, which was displaced ventrolaterally, causing the coronoid process to impinge on the right zygomatic arch. TREATMENT AND OUTCOME: A bilateral partial ostectomy of the rostroventral margins of the zygomatic arches with an autogenous fat graft implantation was performed. The cat recovered without complications and by the following morning was bright, alert, and responsive and eating canned cat food comfortably. One year after surgery, the owner reported that the cat had continued to function well, was eating normally, and had not had any observed locking episodes since surgery. CLINICAL RELEVANCE: Unlike radiographic imaging, computed tomography may be used to create 3-dimensional reconstructions of structures in cases of suspected open-mouth jaw locking; improve evaluation of the lesions; and improve decision-making and client education for diagnosis, treatment options, and prognosis.     

Diagnosis and treatment of dynamic closed-mouth jaw locking in a dog

CASE DESCRIPTION: A 5-year-old neutered male English Bulldog was evaluated for intermittent closed-mouth jaw locking of approximately 1 week's duration. CLINICAL FINDINGS: Initial physical examination revealed a nonpainful inability to open the jaw with and without manual assistance; however, manipulation of the jaw after the dog was sedated for diagnostic imaging restored jaw function. Anesthesia was subsequently induced, and computed tomography was performed with the jaw open and closed; contrast agent-enhanced images of the closed jaw were also obtained. No abnormalities of the temporomandibular joints or retrobulbar space were detected. Fluoroscopic examination of movement of the temporomandibular joints revealed a dynamic interference of the rostrodorsal aspect of the coronoid process of the left mandibular ramus with the medial surface of the frontal process of the left zygomatic bone or the left orbital ligament. TREATMENT AND OUTCOME: Partial excision of the coronoid process of the left mandibular ramus was performed. The dog recovered without complication and was able to open and close its jaw and eat within 6 hours after surgery. No additional episodes of jaw locking were detected during the 6 months after surgery. CLINICAL RELEVANCE: To the authors' knowledge, closed-mouth jaw locking in animals attributable to dynamic interference of the rostrodorsal aspect of the coronoid process of a mandibular ramus with the medial surface of the frontal process of a zygomatic bone or an orbital ligament has not been described. Surgical excision of the coronoid process of the mandibular ramus appeared to provide a successful outcome in the dog of this report.     

Temporomandibular dysplasia in American Cocker Spaniels

Temporomandibular dysplasia was found in six American Cocker Spaniels related to each other. Clinical signs and diagnosis are described.     

Temporomandibular joint injuries and ankylosis in the cat

Objective: To evaluate cause, location, treatment, and the clinical outcome of traumatic temporomandibular joint (TMJ) lesions and TMJ ankylosis in cats. Methods: Cats with TMJ injuries were included in this study. Lesions were classified as luxations, fractures of the condylar process, and intra-articular temporal bone fractures. Signalment, cause and type of injuries, treatment methods, clinical outcome, complications and joint ankylosis were assessed and evaluated statistically. Results: Temporomandibular joint lesions were observed in 82 of 161 cats with maxillofacial injuries. One hundred forty-nine TMJ lesions were determined in 112 joints. Falling was the most common cause and fractures of the condylar process were the most common types of injuries. Isolated TMJ injuries and caudal TMJ luxations were mainly caused by falling. Condylectomy was used in ankylosis, chronic luxation, reluxation and in two cases with multiple TMJ lesions. Ankylosis was observed in 10.97% of cases and was generally observed in fracture combinations of condylar process and mandibular fossa (χ2 = 8.52; p <0.05). No significant relationship between age and development of ankylosis (χ2 = 3.995; p >0.05) was found. Conclusion: In contrast to previous studies, traumatic TMJ lesions were observed in a considerable amount of cats with maxillofacial injuries, and fractures of the condylar process were the most common type. Lesions caused by falling were mostly simple, whereas vehicular trauma caused more complicated lesions. Ankylosis did not appear as a rare condition. Any cat with TMJ injury is susceptible to the development of ankylosis.     

Temporomandibular joint cytokine profiles in the horse

It has been suggested that dental abnormalities lead to temporomandibular joint inflammation and pain that may be mitigated by regular dental care. There is considerable literature on the pathophysiology of equine joint disease including studies on cytokine profiles in diseased appendicular joints. This study examined the effects of age and dental malocclusions summarized as a dental pathology score on equine temporomandibular joint cytokine (IL-1, IL-6, IL-8, TNF alpha and TGF-beta1, -beta2, -beta3) concentrations. TGF-beta3 was not detected in any joint sample. IL-1, IL-6 and TNF alpha were not influenced by age. Foals had significantly lower concentrations of lL-8 and TGF-beta1, and higher levels of TGF-beta2 compared with older horses. Age did not effect cytokine concentration in older horses although there was a trend towards increasing 1L-8 with age. The dental pathology score increased with age in mature horses, however there was no effect of dental pathology score on cytokine concentration. There was no effect of incisor eruption, and presence or number of periodontal lesions on temporomandibular joint cytokine concentration. Our findings indicate that age but not dental pathology affected temporomandibular joint proinflammatory cytokine concentration in this population of horses.     

Changes of hip joint congruity after triple pelvic osteotomy in the dog with hip dysplasia

Changes in hip joint congruity was evaluated in dogs with hip dysplasia before and after triple pelvic osteotomy by computed tomography examination in the standing position. Lateral center edge angle significantly increased, and center distance (CD) significantly decreased after surgery compared to the values before surgery, respectively. There was an inverse proportion between the postoperative period and the change in the ratio of CD. These results suggested that joint laxity was improved with time after surgery, providing evidence of the clinical usefulness of this surgery.     

Temporomandibular subluxation in the dog: A case report

Temporomandibular subluxation was diagnosed in a 2-year old Irish Setter dog. The presenting sign was frequent bouts of open jaw-locking. Tomographic evidence suggested that temporomandibular dysplasia was a factor in the aetiology of the condition. Surgical excision of rostral segments of the zygomatic arches effectively alleviated the clinical condition.     

Symphysiotomy, symphysiectomy, and intermandibular arthrodesis in a cat with open-mouth jaw locking--case report and literature review

A Persian cat was presented with open-mouth jaw locking. It was suspected that abnormal extrusion of the maxillary canine teeth caused contact with the mandibular canine teeth on closure of the mouth, resulting in levering forces that may have led to increased symphyseal mobility, temporomandibular joint laxity, rotational movement of the left mandibular body and locking of the left coronoid process lateral to the zygomatic arch. Symphysiotomy, symphysiectomy, circumferential and interdental wiring, and intraoral resin-based splint application were performed to achieve intermandibular arthrodesis. Following removal of all devices, no further jaw locking episodes were reported during a 33-month follow-up period.     

Hip dysplasia and dog breeding

Summary

Hip dysplasia is considered to be one of the most serious problems in dog breeding. In the past 20 years the studies of, and the attempts to control, this condition have been directed mainly to the overall picture of the abnormality of the hips. The various efforts have resulted in a decrease in the incidence of HD in several breeds of dogs. For other breeds the results have not been very convincing, however. In some instances they are even said to be conflicting with other aims of breeding. Based on these data some separate studies have recently been performded in respect of the details of the disorders in the hip joints and of the heritability of these elements.

The present study concerns itself with the roots of the disorders as they are observed in the various breeds. A great variety of data indicates that selection within the canine species for specific morphological traits must be considered as one of the most important roots of the occurrence of HD. The collected data strongly indicate that improvements in the HD status in the various breeds can be reached by selection against specific disorders of the hip joints in these breeds.