The blood supply to the canine middle ear.

Current descriptions of the anatomy of the blood supply to the canine middle ear are either incomplete or inconsistent, particularly in regards to the vascular branches in close proximity to the temporomandibular articulation (TMJ). To further investigate this blood supply, dissections (n = 9), corrosion casts (n = 4), and computed tomography (n = 8) of canine temporal regions/ears were performed. The goal of this study was to identify and describe branches of the external carotid and maxillary arteries in close proximity to the TMJ that supply the middle ear of the dog. Specific focus was placed on the constancy and origin of the canine rostral tympanic artery since this artery was anticipated to arise from the maxillary artery and enter a foramen at the medial aspect of the mandibular fossa adjacent to the TMJ. New anatomical variations of three canine arteries are described in this study. (1) The rostral tympanic artery is a branch of the temporomandibular ramus and is accommodated by a small foramen located within a depression medial to the temporomandibular joint. (2) A pharyngeal branch of the caudal deep temporal artery was identified. (3) The origin of the caudal auricular artery occurred opposite the lingual artery in 25.8% of dissected specimens, contrary to published descriptions. Anat Rec, 299:907-917, 2016. © 2016 Wiley Periodicals, Inc.

An anatomy precourse enhances student learning in veterinary anatomy.

Veterinary anatomy is often a source of trepidation for many students. Currently professional veterinary programs, similar to medical curricula, within the United States have no admission requirements for anatomy as a prerequisite course. The purpose of the current study was to evaluate the impact of a week-long precourse in veterinary anatomy on both objective student performance and subjective student perceptions of the precourse educational methods. Incoming first year veterinary students in the Louisiana State University School of Veterinary Medicine professional curriculum were asked to participate in a free precourse before the start of the semester, covering the musculoskeletal structures of the canine thoracic limb. Students learned the material either via dissection only, instructor-led demonstrations only, or a combination of both techniques. Outcome measures included student performance on examinations throughout the first anatomy course of the professional curriculum as compared with those who did not participate in the precourse. This study found that those who participated in the precourse did significantly better on examinations within the professional anatomy course compared with those who did not participate. Notably, this significant improvement was also identified on the examination where both groups were exposed to the material for the first time together, indicating that exposure to a small portion of veterinary anatomy can impact learning of anatomical structures beyond the immediate scope of the material previously learned. Subjective data evaluation indicated that the precourse was well received and students preferred guided learning via demonstrations in addition to dissection as opposed to either method alone. Anat Sci Educ 9: 344-356. © 2015 American Association of Anatomists.

The canine jaw-ear connection: The malleomandibular and tympanomandibular ligaments.

In the human, two ligaments derived from the first embryonic pharyngeal (branchial) arch that unite the mandible and temporomandibular joint (TMJ) with the middle ear have been identified as the discomalleolar ligament (DML) and sphenomandibular ligament (SML), also known as the malleomandibular ligament (MML), anterior ligament of the malleus (AML), and tympanomandibular ligament (TML). Neither of these structures has been previously described in the dog. The homologue of the human sphenomandibular ligament (SML) exists in the dog and is represented as a fibrous remnant of Meckel's cartilage. In the newborn puppy, the ligament is a true malleomandibular ligament (MML), extending from the medial mandible to the rostral process of the malleus with no intermittent attachments. In the adult dog, the ligament is entrapped within a bony passageway, likely due to the development and ossification of the tympanic bulla, making it difficult to grossly view the complete course of the ligament. The majority of the ligamentous fibers attach near the tympanic bulla in the adult dog, thus this portion of the ligament has been named the tympanomandibular ligament (TML). Those fibers of the ligament not attaching near the tympanic bulla appear to continue through a canal, located between the tympanic annulus and the surrounding tympanic bone, to become continuous with a connective tissue sheet within the cavity of the middle ear that has attachments to the malleus and incus. Tension on the adult canine TML did not result in movement of the malleus.

Post-anesthesia deafness in dogs and cats following dental and ear cleaning procedures.

OBJECTIVE: The present study was performed to document hearing loss in dogs and cats following procedures performed under anesthesia. Most cases of reported hearing loss were subsequent to dental and ear cleaning procedures. STUDY DESIGN: Prospective and retrospective case survey. ANIMALS: Subjects were dogs and cats with deafness, personally communicated to one author, cases discussed on a veterinary information web site, and cases communicated through a survey of general practice and dental specialist veterinarians. METHODS: Reported deafness cases were characterized by species (dog, cat), breed, gender, age, and dog breed size. RESULTS: Sixty-two cases of hearing loss following anesthesia were reported between the years 2002 and 2009. Five additional cases were reported by survey respondents. Forty-three cases occurred following dental procedures. Sixteen cases occurred following ear cleaning. No relationship was observed between deafness and dog or cat breed, gender, anesthetic drug used, or dog size. Geriatric animals appeared more susceptible to post-anesthetic, post-procedural hearing loss. CONCLUSIONS: Deafness may occur in dogs and cats following anesthesia for dental and ear cleaning procedures, but the prevalence is low. The hearing loss appears to be permanent. CLINICAL RELEVANCE: Deafness can be a consequence following anesthesia for dental or ear cleaning procedures. Older animals may have greater susceptibility.