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Schematic diagram of the external, middle, and internal ear, dog. ( A ) Cross-section through the skull. ( B ) Close up view of the middle and internal ear outlined in the blue square in Fig. 1A. ( A and B courtesy of Dr L.K. Cole and Mr T. Vojt, College of Veterinary Medicine, The Ohio State University, Columbus, OH.)
Source publication
Knowledge of the normal structure and function of the canine and feline ear is critical to be able to diagnose abnormalities that either involve the ear or originate within one or more of the ear compartments. In addition, a veterinarian must be aware of various structures within or associated with the ear so that they are not damaged or destroyed...
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... canine and feline ear can be divided into their component parts, consisting of the pinnae, the external ear canals or external acoustic meatuses, the middle ear, and the internal ear ( Fig. 1 ). Knowledge of the normal structure and function of the ear is critical to be able to diagnose abnormalities that either involve the ear or originate within one or more of the ear compartments. In addition, a veterinarian must be aware of various structures within or associated with the ear so that they are not damaged or destroyed while treating an animal with otic disease. This article provides a brief discussion of the various anatomic features of the ear and normal physiology of portions of the ear. For more in-depth coverage of otic anatomy and physiology, refer to the following references. 1–8 The conformation of the pinnae in the dog may be erect or pendulous. Most cats have erect pinnae. Genetic mutations in the cat have affected the development of the pinnae, and resulted in breeds of cats with four ears, folded ears, and curled ears. Cats with the four-eared condition possess a small extra pinna bilaterally, show reduc- tion of the size of their globes, and have a slightly undershot jaw, with a normal body size. 9 Scottish Fold cats are a unique breed with pinnae that are folded. Up to 4 weeks postnatal, Scottish Fold cats have erect pinnae, and then the tips of the ears begin to fold rostrally. All Scottish Fold cats with the folded-ear phenotype, even if heterozy- gotes, suffer from some degree of osteochondrodysplasia of the distal limbs. 10 The American curl cat breed has pinnae that are curled back at the pinnal apex. Pinnae play an important role in sound localization and also collect sound waves and transmit them to the tympanic membrane. The pinnae are composed of auricular cartilage that is covered on both sides by haired skin complete with apocrine sweat glands, sebaceous glands, and hair follicles. The convex surface of the pinna has more hair follicles per unit area than the thinner concave surface. 11 The muscles of the pinna are numerous and act to move the ear in specific directions. The opening of the external ear canal faces dorsolaterally. The quadrangular plate of cartilage, the tragus, forms the lateral boundary of the ear canal. The antitragus is a thin, elongated piece of cartilage caudal to the tragus and separated from it by the intertragic incisure. The intertragic incisure is the anatomic region used to guide the otoscopic cone or otoendoscope into the ear canal for the otoscopic examination ( Fig. 2 ). The proximal portion of the auricular cartilage becomes funnel shaped forming the vertical ear canal. The vertical ear canal deviates medially just dorsal to the level of the tympanum to form the horizontal ear canal. 12 There is a prominent cartilaginous ridge that separates the vertical and horizontal ear canals and when the ear is in its normal position, makes otic examination of the horizontal ear canal difficult without elevating this ridge by grasping and lifting the ear pinna ( Fig. 3 ). A separate cartilaginous band, the annular cartilage, fits within the base of this conchal tube, giving the external ear canal flexibility. The annular cartilage has fibrous attachments to the osseous external acoustic meatus. The annular cartilage covers the short tubular osseous external acoustic meatus of the tympanic part of the temporal bone. The osseous external acoustic meatus ends at the tympanic annulus. The dorsorostral margin of the external acoustic meatus is in close apposition to a plateau of bone formed by the zygomatic process of the temporal bone ( Fig. 4 ). In most dog breeds, zygomatic process of the temporal bone is short and curved and forms an obtuse angle with the longitudinal axis of the skull. In addition, in most dog breeds, the retroarticular process of the temporomandibular joint is narrow and forms a more obtuse angle relative to the vertical plane. In contrast, some dogs, such as pit bull terriers, have a longer and broader zygomatic process of the temporal bone that forms a right angle or slightly acute angle to the longitudinal axis. The retroarticular process is much broader and longer and forms a much more acute angle relative to the vertical plane (see Fig. 4 ). In aggregate, these variations in pit bull terriers result in an external acoustic meatus that is deeper and possibly better pro- tected relative to the external surface. However, the clinical significance of this deeper location and more acute angles can inhibit the depth of insertion of the otoendoscope when attempting to perform a myringotomy using the video otoscope. The epidermis lining the external ear canal is similar histologically to the pinna; however, in most breeds, hairs are fewer and do not extend the length of the ear canal. 13 A very few fine hairs are found distal to the tympanic membrane. These hairs are a useful landmark when flushing an ear to locate the tympanic membrane in an abnormal ear ( Fig. 5 ). Cocker spaniel dogs typically have excessive compound hair follicles in the horizontal ear canal compared with sparsely distributed, simple hair follicles in ...
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... lodged in the vestibular window with its baseplate held in place by the annular ligament of the vestibular window. The largest of the three cavities is the ventral cavity, occupying the ventromedial portion of the tympanic bulla (see Fig. 9 ). 1,2 Within the middle ear of the dog and cat is a bony septum referred to as the septum bulla ( Fig. 10 ). 1–4 In the dog, the bulla septum is a small, incomplete ridge that only makes contact with the petrous portion of the temporal bone rostrally and often has tiny, elongate bony spicules with bulbous ends. 1,8 In the cat, the septum bulla abuts the petrous portion of the temporal bone and separates the tympanic cavity into two compartments: the dorsolateral epitympanic cavity (pars tympanica) and the ventromedial tympanic cavity (pars endotympanica). 1,4,8 This separation is almost complete, allowing communication between the two compartments only through two small openings: one is between the septum bulla and petrous portion of the temporal bone and the other is located caudally, just lateral to the round window. The difference in the size of this septum between the dog and the cat is of clinical significance in the treatment and management of middle ear disease. Because the bulla septum is very small in the dog, resulting in a large opening between the tympanic cavity proper and the ventral bulla, this allows one to be able to flush the entire tympanic bulla. In the cat, it is only possible to flush the dorsolateral compartment of the tympanic bulla because it is divided into two compartments. Therefore, in most cases of middle ear disease in the cat, surgical management of the ear disease is necessary. In addition, one needs to avoid the use of ointment-based medications or otic packing material instilled into the ear of the cat with a ruptured tympanic membrane, because the medication may leak into the large ventromedial compartment and become trapped. The auditory ossicular chain formed by articulations between the malleus and incus, or the incudomallearis joint, and the incus and the stapes, or the incudostapedius joint, functions as a lever system. In concert with the marked difference in surface area between the tympanic membrane and the footplate of the stapes, the net result is amplification of the initial air pressure wave to account for the increase impedance of the fluid in the membranous labyrinthine compartment of the cochlear of the internal ear. 44 The malleus, the largest of the auditory ossicles, has a long process, the manubrium, embedded in the tympanic membrane. Projecting rostrally from the neck of the malleus is the muscular process, the attachment site for the tensor tympani muscle. Dorsally, the head of the malleus and body of the incus articulate to form the incudomallearis joint, anchored in the epitympanic recess by ligaments. A small branch of the facial nerve, the chorda tympani, exits the facial canal, passes beneath the base of the muscular process of the malleus medial to but in close proximity to the pars flaccida before exiting the middle ear (see Fig. 8 ). 1,2,4 Once beyond the ear, the chorda tympani merges with the lingual branch of the mandibular nerve (cranial nerve V) once exiting through a canal in the rostrodorsal wall of the tympanic bulla to innervate the rostral third of the tongue. 1 Otitis media and traumatic or surgical rupture dorsal in the tympanic membrane can potentially result in impairment of taste. The incus is much smaller that the malleus with two bony extensions or crura ( Fig. 11 ). Although the short crus is largely anchored in the epitympanic recess along with the incudomallearis joint, the long crus extends medially and caudally from the malleus to articulate with the stapes (see Fig. 8 ). 1,2,8 At the distal, medial end of the long crus is a small flat bone, the lenticular process, that articulates with the head of the stapes to form the incudostapedius joint (shown in Figs. 1 and 3 in the article by Garosi elsewhere in this issue). 1,2,4,8 The smallest of the auditory ossicles, the stapes, is a triangular bone that is anchored in the oval or vestibular window by its annular ligament (see Figs. 8 and 11 ). It functions as a piston that transduces tympanic membrane vibrations to fluid waves in the perilymph of the internal ear membranous labyrinthine compartments. 1,2,8 The facial nerve enters the internal acoustic meatus and travels through the facial canal of the petrous portion of the temporal bone, exiting the skull through the stylo- mastoid foramen immediately caudal to the external acoustic meatus. 1–3,8 The facial canal is a bony tunnel that courses through the petrous portion of the temporal bone. In a small region caudal and dorsal to the caudal crus of the stapes, this bony canal is incomplete and exposed to the middle ear compartment. The opening corresponds to the region where the tendon of the stapedius muscle emerges and inserts near the head of the stapes ( Fig. 12 ; also shown in Fig. 1 in the article by Garosi elsewhere in this issue). This opening also corresponds to the location where otitis media can infiltrate through connective tissue and result in facial neuritis. Otitis media resulting in facial nerve paralysis causes facial drooping or spasms and ocular signs. If the patient develops a head tilt, this is a clinical indication of vestibulocochlear nerve involvement caused by an ascending otitis interna (see the article by Garosi elsewhere in this ...
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... the middle ear of the dog and cat is a bony septum referred to as the septum bulla (Fig. 10). [1][2][3][4] In the dog, the bulla septum is a small, incomplete ridge that only makes contact with the petrous portion of the temporal bone rostrally and often has tiny, elongate bony spicules with bulbous ends. 1,8 In the cat, the septum bulla abuts the petrous portion of the temporal bone and separates the tympanic cavity into two ...
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... incus is much smaller that the malleus with two bony extensions or crura (Fig. 11). Although the short crus is largely anchored in the epitympanic recess along with the incudomallearis joint, the long crus extends medially and caudally from the malleus to articulate with the stapes (see Fig. 8). 1,2,8 At the distal, medial end of the long crus is a small flat bone, the lenticular process, that articulates with the ...
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... epitympanic recess along with the incudomallearis joint, the long crus extends medially and caudally from the malleus to articulate with the stapes (see Fig. 8). 1,2,8 At the distal, medial end of the long crus is a small flat bone, the lenticular process, that articulates with the head of the stapes to form the incudostapedius joint (shown in Figs. 1 and 3 in the article by Garosi elsewhere in this issue). 1,2,4,8 The smallest of the auditory ossicles, the stapes, is a triangular bone that is anchored in the oval or vestibular window by its annular ligament (see Figs. 8 and 11). It functions as a piston that transduces tympanic membrane vibrations to fluid waves in the peri- lymph of the ...
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... flat bone, the lenticular process, that articulates with the head of the stapes to form the incudostapedius joint (shown in Figs. 1 and 3 in the article by Garosi elsewhere in this issue). 1,2,4,8 The smallest of the auditory ossicles, the stapes, is a triangular bone that is anchored in the oval or vestibular window by its annular ligament (see Figs. 8 and 11). It functions as a piston that transduces tympanic membrane vibrations to fluid waves in the peri- lymph of the internal ear membranous labyrinthine compartments. 1,2,8 The facial nerve enters the internal acoustic meatus and travels through the facial canal of the petrous portion of the temporal bone, exiting the skull through the ...
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... a bony tunnel that courses through the petrous portion of the temporal bone. In a small region caudal and dorsal to the caudal crus of the stapes, this bony canal is incomplete and exposed to the middle ear compartment. The opening corresponds to the region where the tendon of the stapedius muscle emerges and inserts near the head of the stapes ( Fig. 12; also shown in Fig. 1 in the article by Garosi elsewhere in this issue). This opening also corresponds to the location where otitis media can infiltrate through connective tissue and result in facial neuritis. Otitis media resulting in facial nerve paralysis causes facial drooping or spasms and ocular signs. If the patient develops a ...
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... through the petrous portion of the temporal bone. In a small region caudal and dorsal to the caudal crus of the stapes, this bony canal is incomplete and exposed to the middle ear compartment. The opening corresponds to the region where the tendon of the stapedius muscle emerges and inserts near the head of the stapes ( Fig. 12; also shown in Fig. 1 in the article by Garosi elsewhere in this issue). This opening also corresponds to the location where otitis media can infiltrate through connective tissue and result in facial neuritis. Otitis media resulting in facial nerve paralysis causes facial drooping or spasms and ocular signs. If the patient develops a head tilt, this is a ...
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... auditory tube is a short canal that extends from the nasopharynx to the rostral portion of the tympanic cavity proper (Fig. 13). It functions to equalize pressure on both sides of the tympanic membrane. 46 The auditory tube is divided into three portions: (1) cartilaginous (proximal and opens into the nasopharyx); (2) junctional (part of tube at which the cartilaginous and osseous portions connect); and (3) the osseous potion (distal and opens into the rostral ...
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... petrous portion of the temporal bone is the densest bone in the body, forming the medial margin of the middle ear. It is an angular, conical bone with its apex pointed rostral and ventral (Fig. 14). Relative to other bones of the skull, the petrous portion of the temporal bone is more yellow and does not contain medullary or marrow compartments. A bony bulge that protrudes lateral and ventral from the petrous temporal bone is referred to as the "promontory." 1,2,8 The basal turn of the cochlea is demarcated by this promontory. ...
Citations
... 2,3 The epithelial cells of the TM and ear canal desquamate throughout the external ear canal and migrate to the distal end of the ear canal, contributing to debris removal and repair of TM damage. [4][5][6] As epithelial cells migrate, they desquamate and mix with ceruminous and sebaceous gland secretions and other debris to form cerumen within the ear canal, 5 which is cleared as it moves from the TM to the opening at the distal end of the ear canal through epithelial migration (EM). 4 Therefore, the migration of epithelial cells on the TM and ear canal is integral for healthy ear maintenance and function. ...
... 2,3 The epithelial cells of the TM and ear canal desquamate throughout the external ear canal and migrate to the distal end of the ear canal, contributing to debris removal and repair of TM damage. [4][5][6] As epithelial cells migrate, they desquamate and mix with ceruminous and sebaceous gland secretions and other debris to form cerumen within the ear canal, 5 which is cleared as it moves from the TM to the opening at the distal end of the ear canal through epithelial migration (EM). 4 Therefore, the migration of epithelial cells on the TM and ear canal is integral for healthy ear maintenance and function. ...
Background
Epithelial migration (EM) is integral to normal ear structure and function. Glucocorticoids are considered the first‐line therapy for various external ear disorders; however, their effects on EM on the tympanic membrane (TM) and the external auditory canal (EAC) are understudied.
Hypothesis/Objectives
To test the hypothesis that topical dexamethasone decelerates EM on the TM, this study aimed to evaluate the effects of topical dexamethasone on EM on the TMs of dogs.
Animals
Seven ears of four healthy dogs.
Materials and Methods
The migration distance of an ink drop deposited on the posterior quadrant of the pars tensa (TM EM rate) of dogs was calculated over 3 weeks from images captured with a video‐otoscope. The results were compared by paired Student's t‐test to those obtained from a subsequent experiment in which the same dogs were administered a fresh ink drop at the same position as previously (control group), yet additionally administered 0.1% dexamethasone (0.2 mL/ear) daily for the first 14 days (treatment group).
Results
One of eight ears was excluded because of an anatomical problem. The TM EM rate of the remaining seven ears decreased by 46.74% in the treatment group compared with the control group (p < 0.05).
Conclusions and Clinical Relevance
Topical dexamethasone decelerates EM on the TM of normal dogs' ears. In turn, it is extrapolated that debris removal from the EAC may be slowed, negatively impacting the EAC environment. Consequently, when dogs with otitis receive topical dexamethasone treatment, additional treatment, such as ear canal cleaning, may be required to minimise the effects of impaired TM EM.
... Dogs with ear diseases make up a substantial part of patients in daily veterinary practices. Depending on the manifestation of inflammation, the condition is divided into otitis externa (the external ear canal including the pinna), otitis media (middle ear) and otitis interna (inner ear) [1][2][3][4][5]. ...
Simple Summary
In daily veterinary practice, canine otitis externa is a common presentation and, therefore, many studies were conducted to evaluate predispositions. This study on the other hand aims to evaluate factors that have potentially statistically reduced risks for developing otitis externa. Regarding the results, Rhodesian Ridgebacks and Collies have shown significantly low odds for otitis externa. Furthermore, regarding dogs with endocrinopathies, it was shown that those who are overweight seem to develop otitis externa more likely than those with a normal weight. Especially the latter result should be used in communication with pet owners to point out the importance of strict weight management and, therefore, increasing the quality of life of their dogs.
Abstract
Background: Canine otitis externa is a common presentation in small animal practice. The clinical signs vary individually from patient to patient. Regardless of the expression, they all decrease the quality of life. Therefore, this study aimed to identify factors that showed reduced odds for otitis externa. Methods: Clinical case records were searched for key terms regarding canine otitis. Statistical analyses were applied to evaluate associations with otitis externa. p-values of <0.05 were considered statistically significant. Results: Rhodesian Ridgeback and dogs with underlying infectious diseases had a reduced risk for otitis externa, while Retrievers and dogs with allergies had an increased risk. Furthermore, in the group of dogs with endocrinopathies, those with normal weight showed a reduced risk of developing canine otitis in comparison to those which were overweight. Conclusions: These results show a new point of view to reduce the prevalence of canine otitis by reducing the animals’ weight due to an additional risk of otitis in obese or overweight dogs. Furthermore, for the first time, Rhodesian Ridgebacks were identified in our study population to have a lower risk of developing otitis externa. Thus, breeders should reflect—within other responsibilities for the quality of life in their offspring—on breed-specifics about otitis when planning ahead.
... Images were reviewed by all authors, which included board-certified surgeons with extensive soft tissue experience, and structures in the middle ear visible on the images were identified on the basis of the described anatomy of the middle ear. 2,7,8,[10][11][12][13] The identity of each visible structure in the middle ear was confirmed and recorded, along with the relative position of each structure in relation to other structures in the middle ear. Telescope and light post positions at which each anatomic structure was most easily identified were recorded as well as whether the structure was identifiable from a lateral approach, ventral approach, or both approaches. ...
OBJECTIVE
To describe the anatomic structures of the canine middle ear visible during endoscopic examination through ventral and lateral surgical approaches.
SAMPLE
5 cadaveric canine heads representing 4 breeds.
PROCEDURES
A descriptive study was performed. For each head, a lateral approach was performed on one side and a ventral approach was performed on the opposite side. Images were obtained with a 2.7-mm, 30° telescope.
RESULTS
Captured images were reviewed, and anatomic structures visualized through the lateral and ventral approaches were identified. The optimal approach, telescope position, and light post orientation to identify each anatomic structure were subjectively determined.
CLINICAL RELEVANCE
Middle ear evaluation with a telescope was technically straightforward and allowed identification of middle ear structures not typically visible with an open surgical approach. Findings may serve as an anatomic reference guide for future video-assisted surgical procedures of the middle ear. A better understanding of the location of anatomic structures in the middle ear may help to prevent unnecessary damage to fragile middle ear structures, such as nerves or blood vessels, during surgical procedures.
... All students were required to complete a pre-laboratory reading assignment on canine otoscopy that included text and diagrammatic information on otoscopy and the anatomy of the canine ear canal. 25,26 At the beginning of the laboratory session, students were provided with a review of basic technical skills of canine otoscopy via a demonstration by a board-certified veterinary dermatologist. Students were shown the anatomy of the canine ear canal and tympanic membrane using the teaching specimen and a video otoscope (Karl Storz SE & Co. KG, Tuttlingen, Germany) projecting images synchronously on several screens in the laboratory ( Figure 3). ...
Otoscopic evaluation using an otoscope is an important tool among the diagnostic modalities for otitis externa and is considered a core component of a canine patient’s complete physical examination. Traditionally, otoscopic training in veterinary school involves using live dogs (i.e., laboratory dogs or dogs that are patients of the veterinary teaching hospital). While this approach has its advantages, performing otoscopic examination on live dogs presents several challenges: it requires adequate patient restraint, can cause stress to the dog, and can potentially cause trauma and/or injury to the dog’s ear canal when performed by an inexperienced individual. Using an alternative teaching tool for otoscopic evaluation could overcome these challenges and improve veterinary students’ learning experience. In this study, we investigated student perceptions of a novel canine teaching model for otoscopic evaluation in first-year veterinary students. The Elnady preservation technique was employed to create a realistic, durable, and flexible model for otoscopic training in a dermatology laboratory session in a first-year veterinary course. Student feedback was assessed on a Likert scale, and overall feedback indicated that students felt that the model was beneficial for skill building and removed many of the stressors incurred with using live animals when training in clinical skills. Most students stated that they would like to have additional similar models incorporated into training and would recommend these models to other students.
... 39 During CT-DGT, contrast material may leak into the nasal cavity, flow through the nasopharynx into the auditory tube, and reach the rostral portion of the tympanic cavities. 25,40,41 Establishment of reference ranges for normal nasolacrimal duct width according to body weight in brachycephalic and non-brachycephalic cats is needed for comparative anatomy studies and may help determine whether NLD width is positively associated with epiphora. ...
Objective:
This study sought to describe the anatomical characteristics of the nasolacrimal duct of Persian cats as observed by computed tomographic dacryocystography.
Animal studied:
Ten cats weighing 3-6 kg (three live cats and seven cadaveric specimens).
Procedures:
The animals were submitted to bilateral computed tomographic dacryocystography, totaling 20 nasolacrimal ducts. Dorsal, sagittal, and transverse planes were studied. Two additional skulls were also dissected following latex injection into the nasolacrimal duct. The length and width of the nasolacrimal duct and lacrimal canaliculi, and the distance between the nasolacrimal duct and the root of the upper canine tooth at the point of closest proximity were measured.
Results:
The nasolacrimal duct followed a convoluted course, particularly in the middle and rostral portions. Duct stenosis (width reduction equal to or >75%) and dilations (width increase equal to or >50%) were also detected, particularly in the rostral portion. Nasolacrimal duct length and width ranged from 1.3 to 1.5 cm and 1.5 to 2.3 mm, respectively. Mean lacrimal canaliculus length and width corresponded to 3.1 mm and 0.4 mm, respectively. Mean distance from the nasolacrimal duct to the canine tooth was 2.4 mm. The root of this tooth interfered with the course of the nasolacrimal duct.
Conclusion:
This study provided anatomical information for clinical assessment of the nasolacrimal drainage system in Persian cats.
... In the middle of pars tympanica of the os temporale external hole of the meatus acoustics externus osseous is located. External acoustic meatus (external ear canal) is a tubular path which it is extending from concha auriculare to membrana tympanica and obliquely in dog (Evans, 1993;König, 2007;Njaa et al., 2012). The membrana tympanica at the end of external acoustic meatus is located at an angle of approximately 45 degrees to the horizontal central axis of the external acoustic meatus in dogs, however, this angle may differ according to dog breeds (Njaa et al., 2012). ...
... External acoustic meatus (external ear canal) is a tubular path which it is extending from concha auriculare to membrana tympanica and obliquely in dog (Evans, 1993;König, 2007;Njaa et al., 2012). The membrana tympanica at the end of external acoustic meatus is located at an angle of approximately 45 degrees to the horizontal central axis of the external acoustic meatus in dogs, however, this angle may differ according to dog breeds (Njaa et al., 2012). External acoustic meatus is closed in newborn kittens and puppies. ...
... Many studies are conducted on the morphometric and geometric features of the region (Mann et al., 1979;Albiin, 1984;Djeric and Savic, 1985;Sadler-Kimes et al., 1989;Kemaloğlu et al., 1996;Judkins and Li, 1997;Sırıkçı et al., 2001). In clinical applications, position of the external auditory canal for otoscope application and location of the tympanic membrane during cleaning of the ear canal must be taken into account (Njaa et al., 2012). For example, the dorso-rostral border of the external acoustic meatus and the shape of the zygomatic process of the os temporale and the angle of the skull to the long axis may show variations in different skull types of dogs. ...
In this study, it was aimed to examine the relationship between the morphometric-geometric features of the meatus acusticus externus, bulla tympanica and tuba auditiva and the cranium shape, age, gender and race characteristics in the os temporale region in terms of the clinical-anatomical approach to the outer ear and middle ear regions of the dogs’ skull. In the study, a total of 110 dog's cranium were studied. The bones were photographed in three different views with the camera. The morphometric data on the head, angle measurements and index values related to them were calculated in obtained images. Tuba auditiva angle and meatus acusticus externus angle were found to differ statistically between the age groups. In addition, it was determined that the index values of bulla tympanica, except for the height index, showed statistical differences among age groups. When the angle measurements and index values of the skulls of male and female animals are examined it was determined that other index values did not differ between female and male animals, except for the meatus acusticus externus angle. As a result, it can be said that age and skull type is more effective than gender in the position of the tympanic region in dogs. The results of this research are supportive information that can be used in both clinical and zooarchaeological studies on the bulla tympanica region in dogs.
... Keywords: VetCompass, Electronic patient record, Breed, Dog, Epidemiology, Primary-care, Purebred, Pendulous ear, Erect ear Background Otitis externa describes an inflammatory state of the outer ear canal, with or without pinnal involvement [1]. The external ear canal is lined with epithelial cells, comparable to the ubiquitous epidermis, with variable hair follicles [2,3], sebaceous and ceruminous glands [4], and is populated with a microflora [5]. All these anatomical generalities vary widely between breeds, suggesting that breed should be considered as an important predisposing factor for otitis externa in dogs [2,6]. ...
... The external ear canal is lined with epithelial cells, comparable to the ubiquitous epidermis, with variable hair follicles [2,3], sebaceous and ceruminous glands [4], and is populated with a microflora [5]. All these anatomical generalities vary widely between breeds, suggesting that breed should be considered as an important predisposing factor for otitis externa in dogs [2,6]. Otitis externa cases present across a wide clinical spectrum, ranging from acute inflammatory or inflammatory/infectious to chronic cases, with or without middle ear involvement, and may also be associated with hyperplastic or neoplastic changes [7,8]. ...
Background
Otitis externa is a commonly diagnosed disorder in dogs and can carry a high welfare impact on affected animals. This study aimed to report the prevalence and explore the role of breed and aural conformation as predisposing factors for canine otitis externa in the UK. The study used a cohort design of dogs under UK primary veterinary care at clinics participating in the VetCompass Programme during 2016. Risk factor analysis used multivariable logistic regression modelling.
Results
The study included a random sample of 22,333 dogs from an overall population of 905,554 dogs under veterinary care in 2016. The one-year period prevalence of otitis externa was 7.30% (95% confidence interval [CI]: 6.97 to 7.65). Breed and ear carriage were the highest ranked risk factors. Compared with crossbred dogs, sixteen breed types showed increased odds, including: Basset Hound (odds ratio [OR] 5.87), Chinese Shar Pei (OR 3.44), Labradoodle (OR 2.95), Beagle (OR 2.54) and Golden Retriever (OR 2.23). Four breeds showed protection (i.e. reduced odds) of otitis externa: Chihuahua (OR 0.20), Border Collie (OR 0.34), Yorkshire Terrier (OR 0.49) and Jack Russell Terrier (OR 0.52). Designer breed types overall had 1.63 times the odds (95% CI 1.31 to 2.03) compared with crossbred dogs. Compared with breeds with erect ear carriage, breeds with pendulous ear carriage had 1.76 times the odds (95% CI 1.48 to 2.10) and breeds with V-shaped drop ear carriage had 1.84 times the odds (95% CI 1.53 to 2.21) of otitis externa.
Conclusions
Breed itself and breed-associated ear carriage conformation are important predisposing factors for canine otitis externa. Greater awareness of these associations for both predisposed and protected breeds could support veterinary practitioners to promote cautious and low-harm approaches in their clinical advice on preventive care for otitis externa, especially in predisposed breeds.
... [5][6][7]9,13,15,31 The external acoustic meatus of cats contains ceruminous and sebaceous glands, 9,11,12 with mixed epitrichial and atrichial units, 5,6,24,32 which produce the waxy cerumen emulsion that coats the ear canal surface. 12,33 Cerumen is a mixture of desquamated flattened keratinized squamous epithelial cells and the fatty secretions from sebaceous and ceruminous glands, and helps to maintain barrier function within the ear canal. 1,12,33 In cats, the ceruminous glands of the external acoustic meatus are folded tubular glands with a wide tubular glandular architecture and are surrounded by a single or double layer of myoepithelial cells ( Figure 3). ...
... 12,33 Cerumen is a mixture of desquamated flattened keratinized squamous epithelial cells and the fatty secretions from sebaceous and ceruminous glands, and helps to maintain barrier function within the ear canal. 1,12,33 In cats, the ceruminous glands of the external acoustic meatus are folded tubular glands with a wide tubular glandular architecture and are surrounded by a single or double layer of myoepithelial cells ( Figure 3). The secretory material from these modified sweat glands in and around the ears, eyes and lip margins can be both atrichial (away from the follicular infundibulum) and epitrichial (terminate in the follicular infundibulum). ...
... 6,12 The thin, smooth, epidermally stratified squamous epithelial lining of the external ear canal is histologically similar to that of the pinna and epidermis; 12 however, in most dog breeds, there are less simple single hair follicles within the canal, and the hairs do not extend throughout the length of the canal except in the Cocker Spaniel, which has more compound hair follicles within the acoustic meatus. 2,12,33,36,37 Little has been published regarding this in cats. According to Fernando's 1965 paper, secretions from the cells of the ceruminous glands do not stain histologically on Mallory's triple staining, which differs from what is reported in dogs. ...
Objectives
This study aimed to understand epidemiological factors associated with feline cystadenomatosis, including signalment and papillomavirus PCR status. Cystadenomatosis is an uncommon condition primarily involving the ceruminous and apocrine skin and ear glands.
Methods
This was a retrospective case series. Clinical records from 2011 to 2019 from a tertiary referral hospital in Boston, MA, USA were screened for cases, and case data were re-evaluated and analyzed. The total patient pool contained 65,385 individual cats, of which 797 were referred to the dermatology service. Medical records and biopsy specimens were reviewed; the information collected included signalment, clinical signs, physical examination and diagnostic tests, comorbidities and histopathologic findings. PCR was performed on biopsy specimens to test for papillomavirus DNA.
Results
The cystadenomatosis population consisted of 57 cases (7.1% of total cases referred to the dermatology service) with 105 affected ears. Twenty-seven cases (48 ears) were confirmed via histopathology; four cats (7%) exhibited clinically cystic lesions on the periocular, periorbital and perianal regions; only one cat did not have pinnal lesions. Domestic shorthair cats were most often affected. Relative risk for cystadenomatosis was 2.24 times higher in male cats. In 48 cats (84.2%), ears were bilaterally affected. Seven cats (12.3%) had malignant neoplasia, which included: inflamed adenocarcinoma (n = 5); mast cell tumor (n = 1); or squamous cell carcinoma (n = 1). PCR testing on biopsy specimens from 24 cats revealed feline papillomavirus type 2 DNA in only four cats.
Conclusions and relevance
Cystadenomatosis was more prevalent in senior non-purebred cats, over-represented in male cats and did not appear to be associated with papillomavirus, feline infectious peritonitis, feline immunodeficiency virus/feline leukemia virus status or other identifiable illnesses. Further studies are needed to investigate the causes of cystadenomatosis.
... 78 This mobility of the pinna aids in sound localization. 79 The general pinna vertical features, such as erectness or floppiness, also have an impact on audition. Erect ears are assumed to be especially good at localizing sound at longer distances due to their orientation and accessible funnel-like anatomic properties, but generally this difference from floppyeared dogs is negligible. ...
Canine companions have learned to aid in performing tasks and conducting work for decades. Areas where unique capabilities of working dogs are harnessed are growing. This expansion, alongside efforts to increase domestic purpose-bred stock and awareness of the important role working dogs play in society, is increasing the role veterinarians provide. This article provides a brief overview of 3 key sensory systems in working dogs and highlights considerations for care related to each olfaction, audition, and vision.
... It is important to be familiar with the normal structures of the external and middle ear. 7,8 The TM is a semitransparent membrane separating the external ear canal from the middle ear. It has two sections: the smaller upper pars flaccida and the larger lower pars tensa. ...
A myringotomy is a surgical incision made in the tympanic membrane (TM). This gives access to the middle ear for sampling, flushing and instilling topical therapy. It should be considered whenever the TM is intact and there is clinical evidence of otitis media, abnormal TMs and/or abnormal diagnostic imaging. Samples should be collected for cytological investigation and culture, and then the external ear should be cleaned and dried (if required). Myringotomies should be performed under general anaesthesia and, wherever possible, using a video otoscope; the enhanced view and instrument ports facilitate the technique and reduce the risk of complications. The myringotomy incision should be made in the caudoventral quadrant of the TM using an appropriately sized urinary catheter to collect samples and flush the middle ear cavity. A thorough understanding of the anatomy, technique and potential ototoxicity of topical therapy is needed to minimize the risk of neurological and other complications. The TM usually heals within 35 days if kept free of infection.
