Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors' knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.

This study was carried out to investigate the origin, insertion, direction of muscle fibers and structure of the ear muscles of the Korean native goat. The description was based on the dissection of fifteen Korean native goats with embalming fluid. The ear muscles of the Korean native goat were composed of the Musculus zygomaticoauricularis, M. scutuloauricularis superficialis, M. scutuloauricularis profundus, M. frontoscutularis, M. interscutularis, M. parietoauricularis, M. cervicoscutularis, M. cervicoauricularis superficialis, M. cervicoauricularis medius, M. cervicoauricularis profundus, M. auricularis profundus posterior and M. parotidoauricularis. The M. frontoscutularis clearly seperated into temporal and frontal parts in 6 cases. The M. scutuloauricularis profundus clearly separated into major and minor parts. The M. zygomaticoauricularis blended with the M. parotidoauricularis near its insertion, but not with the M. scutuloauricularis.

OBJECTIVE To establish a method for evaluation of the efficacy of a classical swine fever virus (CSFV) subunit vaccine in rabbits as determined via humoral immune responses to the virus. ANIMALS 40 specific pathogen–free rabbits. PROCEDURES Rabbits were randomly assigned to 4 groups (10 rabbits/group) for SC injection of 0.05, 0.1, and 0.2 mL of a CSFV subunit E2 vaccine (representing 1.15, 2.3, or 4.6 μg of E2 protein/dose, respectively) or saline (0.9% NaCl) solution. Blood samples were collected 21 days after vaccination for measurement of the antibody response against CSFV via ELISA and virus neutralization methods. On the same day, the CSFV Chinese (C) strain was injected into an ear vein. Vaccine efficacy was determined by monitoring of rabbits for pyrexia for 4 days and measurement of viral copies in spleen lysates at the end of the study. Reproducibility of the antibody response was tested with 2 other batches of the vaccine at the minimum immunization dose identified for the initially tested batch. RESULTS The E2 protein dose of the initially tested vaccine was positively correlated with the antibody response and protection rate in rabbits. The identified minimum immunization dose per rabbit was 0.1 mL, representing an E2 protein content of approximately 2.3 μg, and reproducibility of the antibody response to vaccination with the 2 other batches at this dose was good. CONCLUSIONS AND CLINICAL RELEVANCE A method was established in rabbits for evaluation of the efficacy of a CSFV subunit vaccine that could help in the optimization of later large-scale vaccine production and quality control processes as well as in the clinical application of the vaccine.

OBJECTIVE To determine whether an enrofloxacin–silver sulfadiazine emulsion (ESS) labeled for treatment of otitis externa in dogs has ototoxic effects in rabbits following myringotomy. ANIMALS 6 healthy adult New Zealand White rabbits. PROCEDURES Rabbits were anesthetized for brainstem auditory-evoked response (BAER) tests on day 0. Myringotomy was performed, and BAER testing was repeated. Saline (0.9% NaCl) solution and ESS were then instilled in the left and right middle ears, respectively, and BAER testing was repeated prior to recovery of rabbits from anesthesia. Application of assigned treatments was continued every 12 hours for 7 days, and rabbits were anesthetized for BAER testing on day 8. Rabbits were euthanized, and samples were collected for histologic (6 ears/treatment) and scanning electron microscopic (1 ear/treatment) examination. RESULTS Most hearing thresholds (11/12 ears) were subjectively increased after myringotomy, with BAER measurements ranging from 30 to 85 dB in both ears. All day 8 hearing thresholds exceeded baseline (premyringotomy) values; results ranged from 30 to 85 dB and 80 to > 95 dB (the upper test limit) in saline solution–treated and ESS-treated ears, respectively. All ESS-treated ears had heterophilic otitis externa, epithelial hyperplasia of the external ear canal, various degrees of mucoperiosteal edema, and periosteal new bone formation on histologic examination. Scanning electron microscopy revealed that most outer hair cells in the ESS-treated ear lacked stereocilia or were absent. CONCLUSIONS AND CLINICAL RELEVANCE Results supported that ESS has ototoxic effects in the middle ear of rabbits. Further research is needed to confirm these findings. Myringotomized laboratory rabbits may be useful to study ototoxicity of drugs used in human medicine.

OBJECTIVE To determine the optimal anatomic site and directional aim of a penetrating captive bolt (PCB) for euthanasia of goats. SAMPLE 8 skulls from horned and polled goat cadavers and 10 anesthetized horned and polled goats scheduled to be euthanized at the end of a teaching laboratory. PROCEDURES Sagittal sections of cadaver skulls from 8 horned and polled goats were used to determine the ideal anatomic site and aiming of a PCB to maximize damage to the midbrain region of the brainstem for euthanasia. Anatomic sites for ideal placement and directional aiming were confirmed by use of 10 anesthetized horned and polled goats. RESULTS Clinical observation and postmortem examination of the sagittal sections of skulls from the 10 anesthetized goats that were euthanized confirmed that perpendicular placement and firing of a PCB at the intersection of 2 lines, each drawn from the lateral canthus of 1 eye to the middle of the base of the opposite ear, resulted in consistent disruption of the midbrain and thalamus in all goats. Immediate cessation of breathing, followed by a loss of heartbeat in all 10 of the anesthetized goats, confirmed that use of this site consistently resulted in effective euthanasia. CONCLUSIONS AND CLINICAL RELEVANCE Damage to the brainstem and key adjacent structures may be accomplished by firing a PCB perpendicular to the skull over the anatomic site identified at the intersection of 2 lines, each drawn from the lateral canthus of 1 eye to the middle of the base of the opposite ear.

OBJECTIVE To test a unique electronic ear tag designed to collect movement data to determine whether physical activity of sick steers differed from that of healthy steers. ANIMALS 206 steers. PROCEDURES Physical activity in 2 groups of steers during November and December of 2010 (101 steers; the tag of 1 steer failed, and thus that steer was removed from the study, which resulted in data for 100 steers) and 2011 (105 steers) was monitored with an electronic ear tag device with an on-board triple-axis accelerometer. The accelerometer recorded motion in all 3 axes in the form of counts per minute. A radio-frequency transmitter on the ear tag delivered serial packets of motion data to a local server. An algorithm was developed to analyze the activity data to determine whether this technique could be used to assess health status with high accuracy. RESULTS Steers that became sick had significantly fewer activity counts (approx 25% fewer), compared with the activity counts of steers that remained healthy the entire time. CONCLUSIONS AND CLINICAL RELEVANCE In this study, automated detection of health status in growing cattle was feasible through remote monitoring of animal activity. Early identification of sick animals should lead to improved health outcomes, increased marketability, and improved animal well-being and help to minimize the use of antimicrobials that could contribute to resistant bacteria.

Objective-To evaluate the osseous structures of the external acoustic meatus, tympanic cavity, and tympanic bulla of llamas (Lama glama) by use of computed tomography (CT) and establish measurement values for use in detection of abnormalities associated with the external or middle ear in llamas. Animals-10 adult llama heads without any evidence of ear disease. Procedures-Heads of 10 healthy llamas euthanized by use of a captive bolt striking the dorsal aspect of the skull were collected. Transverse images of the heads were acquired with 1-mm slice thickness, and images were reconstructed in sagittal and dorsal planes. Measurements of the bony structures of the external and middle ear of each head were obtained. Results-The osseous external acoustic meatus curved ventrally as it tracked medially. Its narrowest portion was located at the level of the tympanic annulus. The tympanic bulla conformation differed widely from the bubble-shaped tympanic bulla in dogs and cats. The bulla was divided by the stylohyoid fossa into a larger caudolateral and a smaller caudomedial process; its interior had a honeycombed structure with pneumatized cells similar to the honeycombed appearance of the human mastoid process. Conclusions and Clinical Relevance-Results provided new information regarding the shape and dimensions of the osseous external and middle ear structures in adult llamas without ear disease. Specific landmarks for location of the external acoustic meatus, tympanic cavity, and tympanic bulla in relation to each other were identified. Knowledge of the CT appearance of normal structures will help clinicians to identify changes attributable to middle ear otitis, external ear canal stenosis, or congenital malformations of the ear in this species.

OBJECTIVE To assess the extent of damage to the skull and brain of cadaveric dairy goat kids caused by a .22-caliber, 16-g pellet fired from a multipump air pistol at various power levels. SAMPLE Cadavers of 8 male and 7 female dairy goat kids ≤ 5 days old. PROCEDURES Each cadaver was positioned in sternal recumbency with the head and neck extended on a straw bale. A multipump air pistol was held with the barrel perpendicular to and 2.5 cm from the head at the intersection of 2 imaginary lines that extended from the lateral canthus of each eye to the middle of the contralateral ear base and fired at half (5 pumps; n = 2), intermediate (7 pumps; 2), or full (10 pumps; 11) power. The head and neck were removed from the carcass for CT imaging and gross sectioning to determine the location of the pellet and extent of damage caused to the skull and brain. RESULTS The pellet successfully penetrated the skull of all 13 heads shot at full or intermediate power and 1 of the 2 heads shot at half power. The pellet did not fragment after entering the skull of any cadaver and penetrated the brainstem (necessary for instantaneous death) in only 7 cadavers. CONCLUSIONS AND CLINICAL RELEVANCE The described technique was insufficient for use as a stand-alone method for euthanizing young dairy goat kids. Modification of the technique warrants further research to determine whether air pistols can be used to effectively euthanize young goat kids.

Ear mite (Otodectes cynotis)is a very common cause of otitis externaand it is one of the clinically importantdiseases of cats and dogs. A study on earmite infestation was carried out on straycats around the vicinity of Kota Bharutown. This study was done to establish theincidence of positive infections by directsmear of skin scrapings from cats. A total of34 skin scraping and ear swab samples weretaken from stray cats around Kota Bharu,Kelantan. The study was conducted in fourlocations around the Kota Bharu district,namely; Pasar Pasir Tumbuh, Pasar MedanBuluh Kubu, Kampung Kraftangan andRural Transformation Centre in Tunjung.A total of 7 samples from RTC Tunjungarea were positive for these mites, observedunder the microscope. This area also hasa wet market where the stray cats live andas the environment is damp and dirty, it isthe perfect environment for the spread ofthe mites. This information is vital for thecontrol of stray animal populations whichindirectly affect human health.