Bilateral Extracapsular Soft-Tissue Ossification Affecting Range of TMJ Motion in an Airedale Terrier

Management of bilateral pterygoid myositis ossificans-like lesion in dogs

Myositis ossificans (MO) and myositis ossificans-like lesions have been rarely described within the veterinary literature, and are even less common in the maxillofacial region. When MO affects the muscles of mastication, it can result in complete or partial inability to open the mouth. As with other conditions resulting in decreased or restricted mandibular range of motion, severe and potentially fatal sequelae such as difficulty with prehension, swallowing, and air exchange are possible. Diagnostic imaging is essential in achieving an accurate diagnosis and in formulating an appropriate treatment plan. In this “method” manuscript, we provide a detailed description of our approach to diagnosis and surgical management of MO-like lesions of the pterygoid muscles and describe our experience with two young French bulldogs.

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 44.0^o (+/- 4.1+^o) and anesthetized patients 43.9^o (+/- 3.9^o). No difference was seen in the gape angle between dental (44.2^o) and non-dental patients (43.2^o) (p = 0.183), or between conscious (43.8^o) and anesthetized patients (43.7^o) (p = 0.610). This study suggests that a consistent gape angle of 44^o 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.

Ankylosis and pseudoankylosis of the temporomandibular joint in 10 dogs (1993-2015)

OBJECTIVE

To describe the clinical features and results of treatment of true ankylosis and pseudoankylosis of the temporomandibular joint in dogs.

METHODS

This study was a retrospective case series. Ten client-owned dogs that were presented for inability to open the mouth or a severely decreased range of motion of the temporomandibular joint were included. Information on the surgical procedures performed and the perioperative complications were documented. Three-dimensional printing of the skull was performed in four dogs.

RESULTS

Two dogs were diagnosed with temporomandibular joint ankylosis and seven dogs with pseudoankylosis. One dog had evidence of combined temporomandibular joint ankylosis and pseudoankylosis. Of the seven dogs with pseudoankylosis, six had an osseous fusion involving the zygomatic arch and mandible. Surgical treatment was performed in nine dogs and a revision surgery was needed in one dog. Follow-up ranged from five months to eight years (mean: 48.6 months). Eight out of nine dogs that were treated surgically regained the ability to open their mouth, but six dogs never regained a fully normal temporomandibular joint range of motion.

CLINICAL SIGNIFICANCE

Temporomandibular joint ankylosis and pseudoankylosis are uncommon in the dog. Surgical treatment for temporomandibular joint ankylosis or pseudoankylosis in dogs is a successful option and carries a prognosis dependent on patient-specific abnormalities. Computed tomography complemented with three-dimensional printing is valuable for understanding the extent of abnormalities and for preoperative planning.

Vertical Mandibular Range of Motion in Anesthetized Dogs and Cats

The main movement of the temporomandibular joint of dogs and cats is in vertical dimensions (opening and closing the mouth). An objective evaluation of the vertical mandibular range of motion (vmROM) may favor early diagnosis of a number of conditions affecting the joint mobility. vmROM, corresponding to the maximum interincisal opening, was measured in 260 dogs and 127 cats anesthetized between June 2011 and April 2015 because of oral or maxillofacial problems and procedures. Animals with a known history of or having current diseases considered to hamper mandibular extension were excluded from the study. Dogs were divided into four subgroups, based on body weight: subgroup 1 (≤5.0 kg, 51 dogs), subgroup 2 (5.1–10.0 kg, 56 dogs), subgroup 3 (10.1–25 kg, 66 dogs), and subgroup 4 (>25.1 kg, 87 dogs). The mean vmROM of all dogs was 107 ± 30 mm (median 109, range 40–180); in subgroup 1 was 67 ± 15 mm (median 67, range 40–100), in subgroup 2 was 93 ± 15 mm (median 93, range 53–128), in subgroup 3 was 115 ± 19 mm (median 116, range 59–154), and in subgroup 4 was 134 ± 19 mm (median 135, range 93–180). The mean vmROM of the cats was 62 ± 8 mm (median 63, range 41–84). Correlations between vmROM, age, sex, and body weight were evaluated. In dogs, vmROM did not correlate with age, and in cats a weak positive correlation was found. vmROM and body weight were positively correlated in both populations, except dog subgroup 2. Overall, mean vmROM and body weight were significantly higher in male than in female, both in dogs and in cats. However, vmROM did not differ between sexes in any of the canine subgroups, and only in subgroup 4 male dogs were significantly heavier than females. Evaluation of vmROM should be incorporated into every diagnostic examination as it may be valuable in showing changes over time for every single patient.

IMAGING DIAGNOSIS-MAGNETIC RESONANCE IMAGING FEATURES OF CRANIOMANDIBULAR OSTEOPATHY IN AN AIREDALE TERRIER

An Airedale Terrier was presented for evaluation of depression and reluctance to be touched on the head. Magnetic resonance (MR) imaging of the head was performed. The images revealed bone lesions affecting the calvarium at the level of the coronal suture and left mandibular ramus, with focal cortical destruction, expansion, and reactive new bone formation. Skull lesions were hypointense on T1-weighted sequences, hyperintense on T2-weighted sequences, and showed an intense and homogeneous enhancement after gadolinium administration. Reactive new bone formation and periosteal proliferation were confirmed histopathologically. The clinical signs, imaging findings, and histopathological examination were consistent with craniomandibular osteopathy.