Chiari-like malformation in Cavalier King Charles Spaniels impacts brainstem auditory-evoked response latency results.

OBJECTIVE: To evaluate hearing loss in Cavalier King Charles Spaniels (CKCS), breed-specific brainstem auditory-evoked response (BAER) testing parameters are needed to help assess the Chiari-like malformation (CM) grade. The purpose of this study was to establish breed-specific BAER data and to determine if BAER indexes differed based on the CM grade. We hypothesized that there would be latency differences based on the CM grade. ANIMALS: 20 CKCS without apparent hearing abnormalities as assessed by the owners. PROCEDURES: Under general anesthesia, CKCS underwent a CT scan (to assess the middle ear), BAER testing, and MRI (to assess the grade of CM). RESULTS: No CKCS had CM0. Nine (45%) CKCS had CM1; 11 (55%) had CM2. All had at least 1 morphologic abnormality in waveforms. Absolute and interpeak latencies were reported for all CKCS and compared between CM grades. The median threshold for CKCS with CM1 was 39 and for CM2 was 46. Absolute latencies for CKCS with CM2 were consistently longer than those for CKCS with CM1 with the exception of waves II and V at 33 dB. Significant differences were found for wave V at 102 dB ( P = .04) and wave II at 74 dB (P = .008). Interpeak latency comparisons were inconsistent between CM1 and CM2. CLINICAL RELEVANCE: Breed-specific BAER data for CKCS with CM1 and CM2 were established. The results suggest that CM impacts BAER latency results, but the influence of the malformation is not always statistically significant or predictable.

Noncompartmental pharmacokinetics of three intravenous mycophenolate mofetil concentrations in healthy Standardbred mares.

BACKGROUND: Mycophenolate mofetil (MMF) is the prodrug of mycophenolic acid (MPA) which acts as an immunosuppressive agent. During the biotransformation of MMF to MPA, additional metabolites including MPA phenol glucuronide (MPAG), MPA acyl glucuronide (AcMPAG) and MPA phenol glucoside (MPG) are formed. OBJECTIVE: To define the noncompartmental pharmacokinetic (PK) parameters of three single doses of intravenous (i.v.) MMF and its downstream metabolites in healthy horses. ANIMALS: Six healthy Standardbred mares. MATERIALS AND METHODS: Generic MMF (Par Pharmaceuticals; Chestnut Ridge, NY, USA) was reconstituted and administered as a single i.v. bolus at 1.0 mg/kg, 5.0 mg/kg and 10.0 mg/kg with an eight day washout between treatments. Blood samples were collected immediately before MMF administration and over 24 h. A liquid chromatography-tandem mass spectrometry assay was developed following FDA guidance to determine plasma MMF, MPA, MPAG, AcMPAG and MPG concentrations. Plasma concentrations were analysed independently, followed by calculation of geometric mean and coefficient of variation. RESULTS: Noncompartmental PK parameters were determined for MMF and all metabolites at all doses. MMF was rapidly converted to MPA in all horses. Each incremental dose of MMF resulted in increases in Cmax and AUCinf _obs for MPA and the three additional metabolites. Within the 10-fold dose range, the increase in Cmax and AUCinf _obs for MMF and its metabolites was nonlinear. CONCLUSIONS AND CLINICAL RELEVANCE: Horses biotransform MMF into MPA, MPAG, AcMPAG and MPG via the glucuronidation and glucosidation clearance pathways. Equine reference PK profiles for MPA and the metabolites, MPAG, AcMPAG and MPG were established.

Normative wideband acoustic immittance patterns for middle ear evaluation in dogs.

The objective of this study was to investigate the clinical use of wideband acoustic immittance (WAI) reflectance for middle ear assessment in dogs. Otoscopy and brainstem auditory evoked response testing was performed on all dogs prior to the WAI assessment. Following calibration, dogs were comfortably restrained while the probe was placed into the ear canal to obtain recordings. Testing was repeated for replicability. Repeatable WAI reflectance patterns were observed in 24 dogs, characterized by low-reflectance resonant peaks at approximately 1500-1800 Hz and 3000-4000 Hz. Observed patterns suggest WAI may be a practical means of assessing middle ear function in dogs.

Is low-level laser therapy useful as an adjunctive treatment for canine acral lick dermatitis? A randomized, double-blinded, sham-controlled study.

BACKGROUND: Conventional therapy for canine acral lick dermatitis (ALD) consists of systemic antibiotics and anti-anxiety medications. Low-level laser therapy (LLLT) is a noninvasive therapy used to treat inflammatory and painful conditions. HYPOTHESIS/OBJECTIVES: The primary objective was to determine whether LLLT with conventional therapy would be beneficial as an adjunct treatment for ALD. We hypothesized that LLLT and conventional therapy combined would result in a greater reduction in licking Visual Analog Score (LVAS) compared to conventional therapy alone. Secondary objectives were to assess change in lesion/ulcer size, thickness and hair growth. ANIMALS: Thirteen dogs with a skin lesion consistent with ALD. METHODS AND MATERIALS: Dogs were randomly assigned to two groups. All dogs received systemic antibiotics and trazodone. The treatment group (TG) received LLLT by laser (130 mW, 2 min) with blue and red light-emitting diodes (LEDs), while the control group (CG) had sham therapy (laser/LEDs off). Treatments were administered three times weekly for two weeks, then twice weekly for two weeks for a total of 10 visits. Descriptive statistics were performed (mean, median); primary and secondary objectives were assessed with nonparametric ANOVA (Kruskal-Wallis test), with significance set at P < 0.05. RESULTS: Thirteen dogs (six CG, seven TG) were enrolled. There were no significant differences in median LVAS, lesion/ulcer size or thickness of the ALD lesion between TG and CG. There was a significantly greater increase (24%) in hair growth in TG (P = 0.0081) compared to CG. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment of ALD requires multimodal therapy. Although combining LLLT with conventional therapy did not result in a significantly greater reduction in LVAS, there was a significant increase in hair growth compared to conventional therapy alone.

Comparison of high-field MRI and multidetector CT for grading Chiari-like malformation and syringomyelia in Cavalier King Charles Spaniels.

Chiari-like malformation (CM) and syringomyelia (SM) are common illnesses that can cause debilitating neuropathic pain in Cavalier King Charles spaniels (CKCS). The current imaging modality to screen CKCS for CM/SM is MRI of the brain and cervical spine. Magnetic resonance imaging provides good soft tissue detail and contrast of the cerebellum and cervical spinal cord. Computed tomography (CT) is another cross-sectional imaging technique that facilitates brain and neck evaluation; however, soft tissue resolution does not match that of MRI. Computed tomography benefits include identification of concurrent craniocervical junction anomalies (atlantooccipital overlap) and shorter imaging/anesthesia times with the ability to use only sedation. The aim of this retrospective, method comparison study is to assess the utility of multidetector CT for screening CM and SM in CKCS as compared to high-field MRI. Three groups of observers with different levels of experience graded CM and SM based on the British Veterinary Association/Kennel Club CM/SM classification criteria. Thirty CKCS underwent multidetector CT and 3 Tesla MRI studies. Computed tomography and MRI studies were reviewed at different timepoints to minimize bias. Computed tomography has lower Cohen's Kappa agreement for each observer group compared to MRI. The intraclass correlation coefficient averaging CM and SM for all groups was excellent using MRI, while CT was poor for SM and moderate for cerebellar herniation. Greater observer experience resulted in a higher agreement for CT and MRI. Magnetic resonance imaging should remain the standard for screening of CM and SM as CT can result in misclassification and greater disagreement.

Mechanical quantitative sensory testing in cavalier King Charles spaniels with and without syringomyelia.

BACKGROUND: Syringomyelia (SM) is a debilitating condition in the cavalier King Charles spaniel (CKCS) that results in neuropathic pain and diminished quality of life. Von Frey aesthesiometry (VFA) is a method of mechanical quantitative sensory testing that provides an objective sensory threshold (ST) value and can be used to quantify neuropathic pain (NP) and monitor response to therapy. The utility of VFA has been previously established in client-owned dogs with acute spinal cord injury but the technique has not been evaluated in dogs with SM. The goal of this study was to evaluate ST, as determined by VFA, in dogs with and without SM, to assess the utility of VFA in quantifying NP in SM-affected dogs. We hypothesized the SM-affected CKCS would have lower ST values, consistent with hyperesthesia, when compared to control CKCS. Additionally, we hypothesized that ST values in SM-affected dogs would be inversely correlated with syrinx size on MRI and with owner-derived clinical sign scores. RESULTS: ST values for the thoracic and pelvic limbs differed significantly between the SM-affected and control CKCS (p = 0.027; p = 0.0396 respectively). Median ST value (range) for the thoracic limbs was 184.1 g (120.9-552) for control dogs, and 139.9 g (52.6-250.9) for SM-affected dogs. The median ST value (range) for the pelvic limbs was 164.9 g (100.8-260.3) in control dogs and 129.8 g (57.95-168.4) in SM-affected dogs. The ST values in SM-affected dogs did not correlate with syrinx height on MRI (r = 0.314; p = 0.137). Owner-reported clinical sign scores showed an inverse correlation with pelvic limb ST values, where dogs with lower ST values (hyperesthesia) were reported by their owners to display more frequent and severe clinical signs (r = - 0.657; p = 0.022). CONCLUSION: ST values were lower in SM-affected CKCS compared to control dogs, suggesting the presence of neuropathic pain. Dogs with lower ST pelvic limb values were perceived by their owners to have more severe clinical signs classically associated with SM. Our results suggest that VFA might offer quantitative assessment of neuropathic pain in SM-affected dogs and could be useful for monitoring response to therapy in future clinical studies.

Bacteriology and cytology of otic exudates in 41 cavalier King Charles spaniels with primary secretory otitis media.

BACKGROUND: Primary secretory otitis media (PSOM) in the cavalier King Charles spaniel (CKCS) is similar to otitis media with effusion (OME) in humans. A proposed aetiology of OME is inflammation of the middle ear mucosa, usually due to bacterial infection, leading to auditory tube dysfunction. HYPOTHESIS/OBJECTIVES: Our objective was to characterize the microbiological and cytological findings of otic exudates from the external ear canal (EEC) (n = 68) and middle ear (ME) (n = 69) from 41 CKCSs with PSOM. METHODS AND MATERIALS: Swab samples from the EEC and mucus aspirated from the ME after performing a myringotomy were obtained for bacterial culture and cytological analysis. RESULTS: Fifty-five of 68 (81%) EEC and 46 of 69 (67%) ME yielded no bacterial growth. Thirty-eight of the 68 (56%) ears had no microbial growth from neither the EEC nor ME; seven (10%) had bacteria isolated from the EEC only; 17 (25%) had bacteria isolated from the ME only, and six (8%) had bacteria isolated from both EEC and ME. Thirty-four total bacterial isolates were cultured from ME. The most common bacterial species isolated were coagulase-negative staphylococci, followed by Staphylococcus pseudintermedius. Otic cytology identified coccoid organisms in only three of 68 EEC and four of 69 ME. CONCLUSIONS: The role of bacteria in the pathogenesis of PSOM in CKCS is unclear. The majority of the EEC and ME of the CKCS with PSOM were negative by conventional bacterial culture and the cytological presence of bacteria was not correlated with culture positives. The potential role of noncultivable microbiota in PSOM requires exploration using molecular methods.

An evaluation of veterinary allergen extract content and resultant canine intradermal threshold concentrations.

BACKGROUND: Limited information is available for dogs on threshold concentrations (TCs), and the protein composition of common allergenic extracts produced by different manufacturers. HYPOTHESIS/OBJECTIVES: To characterize the protein heterogeneity of tree, grass, weed and mite allergens from different lots of allergenic extracts, and to determine intradermal TCs for healthy dogs using extracts from two manufacturers. ANIMALS: Twenty five privately owned, clinically healthy dogs and ten purpose-bred beagle dogs. METHODS AND MATERIALS: Protein concentration and heterogeneity of 11 allergens from two manufacturers were evaluated using a Bradford-style assay and SDS-PAGE. Intradermal testing was performed with 11 allergens from each company at four dilutions. Immediate reactions were subjectively scored (0 to 4+), and objectively measured (mm) and their percentage concordance evaluated. Model-based TCs were determined by fitting positive reactions (≥2+) at 15 min to generalized estimating equations. RESULTS: Allergen extract protein quantity and composition varied within and between manufacturers despite sharing the same PNU/mL values. Model-based TCs of one weed, five trees, two grasses and a house dust mite were determined for extracts from Manufacturer 1 (M1), and for extracts of three weeds, three trees and two grasses from Manufacturer 2 (M2). Receiver operating characteristic curve analyses determined a percentage concordance of the objective and subjective measurements of 77.3% for M1 and 75% for M2 allergens. CONCLUSIONS AND CLINICAL IMPORTANCE: Veterinary allergen extracts labelled as the same species and PNU/mL are not standardized; they show heterogeneity in composition and potency within and between manufacturers. Variability in extract content may require adjustment of intradermal testing concentrations.

Conductive hearing loss in four dogs associated with the use of ointment-based otic medications.

BACKGROUND: Hearing loss (HL) is classified as conductive when sound transmission is compromised in the ear canal or middle ear, or sensorineural when there is an abnormality of the receptor cells of the cochlea or auditory pathway. Hearing in dogs is evaluated using the brainstem auditory evoked response (BAER) test. HYPOTHESIS/OBJECTIVES: Our objective was to characterize BAER findings pre- and post-ear flushing in four dogs with acute HL following application of an ointment-based otic medication containing betamethasone, clotrimazole and gentamicin in a mineral oil-based system containing a plasticized hydrocarbon gel. ANIMALS: Dogs, ranging from 9 to 11 years old, that had been treated with the otic medication for one to three weeks prior to hearing loss and on otoscopic examination had evidence of medication in the horizontal ear canals. METHODS: Dogs were anaesthetized for an ear flush to remove the medication from the ear canals. Hearing was assessed using BAER testing, measurements were initiated with 116 decibel peak equivalent sound pressure level (dBpeSPL) click. Estimated threshold was defined as the lowest intensity in dB in which wave V was still present. RESULTS: Post-ear flush the estimated threshold improved in both ears of all dogs (mean 22.3 dB; range 13-41 dB), confirming conductive HL due to the otic medication. All owners noted an improvement in their dog's hearing post-ear flush, validating the BAER findings. CONCLUSIONS AND CLINICAL IMPORTANCE: These results emphasize the importance of an ear flush to remove otic medications in dogs that experience acute HL, to determine if the HL is conductive, and if so, to restore hearing.

In vitro bactericidal activity of blue light (465 nm) phototherapy on meticillin-susceptible and meticillin-resistant Staphylococcus pseudintermedius.

BACKGROUND: Staphylococcus pseudintermedius is the most common cause of bacterial skin infections in dogs. Meticillin-resistant infections have become more common and are challenging to treat. Blue light phototherapy may be an option for treating these infections. HYPOTHESIS/OBJECTIVES: The objective of this study was to measure the in vitro bactericidal activity of 465 nm blue light on meticillin-susceptible Staphylococcus pseudintermedius (MSSP) and meticillin-resistant Staphylococcus pseudintermedius (MRSP). We hypothesized that irradiation with blue light would kill MSSP and MRSP in a dose-dependent fashion in vitro as previously reported for meticillin-resistant Staphylococcus aureus (MRSA). METHODS: In six replicate experiments, each strain [MSSP, n = 1; MRSP ST-71 (KM1381) n = 1; and MRSA (BAA-1680) n = 1] were cultivated on semisolid media, irradiated using a 465 nm blue light phototherapeutic device at the cumulative doses of 56.25, 112.5 and 225 J/cm2 and incubated overnight at 35°C. Controls were not irradiated. Colony counts (CC) were performed manually. Descriptive statistics were performed and treatment effects assessed using the Wilcoxon-Mann-Whitney rank-sum test. Bonferroni-corrected rank-sum tests were performed for post hoc analysis when significant differences were identified. RESULTS: There was a significant decrease in CC with blue light irradiation at all doses for MRSA (P = 0.0006) but not for MSSP (P = 0.131) or MRSP (P = 0.589). CONCLUSIONS: Blue light phototherapy significantly reduced CC of MRSA, but not of MSSP or MRSP. The mechanism for the relative photosensitivity of the MRSA isolate is unknown, but is hypothesized to be due to an increased concentration of porphyrin in S. aureus relative to S. pseudintermedius, which would modulate blue light absorption.

Diagnosis of primary secretory otitis media in the cavalier King Charles spaniel.

BACKGROUND: Primary secretory otitis media (PSOM) is a disease reported in the cavalier King Charles spaniel (CKCS). The diagnosis of PSOM has been made based only on visualization of a bulging tympanic membrane and mucus in the middle ear post-myringotomy. No additional tests have been evaluated for the diagnosis of PSOM; CKCSs with early disease may have been missed. HYPOTHESIS/OBJECTIVES: The objective of this study was to compare otoscopy, tympanometry, pneumotoscopy and tympanic bulla ultrasonography, using computed tomography (CT) as the gold standard for the diagnosis of PSOM in the CKCS. ANIMALS: Sixty CKCSs with clinical signs suggestive of PSOM. METHODS: Otoscopy, CT scan, tympanic bulla ultrasonography, tympanometry and pneumotoscopy were performed; those CKCSs with a soft tissue density in the middle ear identified on CT had a myringotomy and middle ear flush. RESULTS: Forty-three (72%) CKCSs had PSOM (30 bilateral, 13 unilateral). A large bulging pars flaccida was identified in only those CKCS with PSOM (specificity of 100%); however, only 21 of 73 ears with PSOM had a large bulging pars flaccida (sensitivity of 29%). Sensitivity and specificity for tympanometry, pneumotoscopy and tympanic bulla ultrasonography were (84%, 47%), (75%, 79%) and (67%, 47%), respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Based on these results a large bulging pars flaccida indicates the presence of PSOM, whereas a flat pars flaccida may be present in CKCS that have PSOM as well as those that do not. In CKCSs with a flat pars flaccida none of the above diagnostic tests can be recommended in place of CT scan for the diagnosis of PSOM.

Effect of feeding on the pharmacokinetics of oral minocycline in healthy research dogs.

BACKGROUND: The effect of food on minocycline oral absorption in dogs is unknown. OBJECTIVE: The objective was to determine the pharmacokinetics of minocycline after administration of a single oral dose in fed and fasted dogs. METHODS: Ten research hounds were administered oral minocycline (approximately 5 mg/kg) with and without food, in a crossover study, with a one-week wash-out between treatments. Blood samples were collected immediately prior to minocycline administration and over 24 h. Minocycline plasma drug concentrations were measured using high-performance liquid chromatography using ultraviolet detection and were analysed with compartmental modelling to determine primary pharmacokinetic parameters. Each dog was analysed independently, followed by calculation of means and variation of the dogs. The Wilcoxon signed-rank test [analysing secondary pharmacokinetic parameters - peak concentration (CMAX ), area under the concentration versus time curve (AUC)] was used to compare the two groups. A population pharmacokinetic modelling approach was performed using nonlinear mixed effects modelling of primary parameters for the population as fixed effects and the difference between subjects as a random effect. Covariate analysis was used to identify the source of variability in the population. RESULTS: No significant difference was found between treatments for AUC (P = 0.0645), although AUC was higher in fasted dogs. A significant difference was found for CMAX (P = 0.0059), with fasted dogs attaining a higher CMAX . The covariate of fed versus fasted accounted for a significant variation in the pharmacokinetics. CONCLUSIONS AND CLINICAL IMPORTANCE: Because feeding was a significant source of variation for the population's primary pharmacokinetic parameters and fasted dogs had higher minocycline concentrations, we recommend administering minocycline without food.

Evaluation of canine-specific minocycline and doxycycline susceptibility breakpoints for meticillin-resistant Staphylococcus pseudintermedius isolates from dogs.

BACKGROUND: Using the US Clinical and Laboratory Standards Institute (CLSI) human tetracycline breakpoints to predict minocycline and doxycycline susceptibility of Staphylococcus pseudintermedius (SP) isolates from dogs is not appropriate because they are too high to meet pharmacokinetic/pharmacodynamic data using a standard dose. New breakpoints have been approved for doxycycline and proposed for minocycline. Revised breakpoints are four dilutions lower than tetracycline breakpoints, providing a more conservative standard for classification of isolates. HYPOTHESIS/OBJECTIVES: The objectives of this study were to measure minimum inhibitory concentrations (MICs) of minocycline and doxycycline of 100 canine meticillin-resistant SP clinical isolates, compare their susceptibilities to minocycline and doxycycline based on current and revised standards, and document their tetracycline resistance genes. METHODS: E-test strips were used to determine MICs. PCR was used to identify tet genes. RESULTS: Using the human tetracycline breakpoint of MIC ≤ 4 µg/mL, 76 isolates were susceptible to minocycline and 36 isolates were susceptible to doxycycline. In contrast, using the proposed minocycline breakpoint (MIC ≤ 0.25 µg/mL) and approved doxycycline breakpoint (MIC ≤ 0.125 µg/mL), 31 isolates were susceptible to both minocycline and doxycycline. Thirty-one isolates carried no tet genes, two had tet(K) and 67 had tet(M). CONCLUSIONS AND CLINICAL IMPORTANCE: Use of the human tetracycline breakpoints misclassified 45 and five of the isolates as susceptible to minocycline and doxycycline, respectively. PCR analysis revealed that 43 and five of the isolates classified as susceptible to minocycline and doxycycline, respectively, possessed the tetracycline resistance gene, tet(M), known to confer resistance to both drugs. These results underscore the importance of utilizing the proposed minocycline and approved doxycycline canine breakpoints in place of human tetracycline breakpoints.

The effect of ketoconazole on whole blood and skin ciclosporin concentrations in dogs.

BACKGROUND: Ciclosporin (CSA) is approved for the treatment of canine atopic dermatitis. Ciclosporin is metabolized by liver cytochrome P450 enzymes, a process inhibited by ketoconazole (KTZ). HYPOTHESIS/OBJECTIVES: The aims of this study were to determine skin and blood CSA concentrations when CSA was administered alone at 5.0 (Treatment 1) or 2.5 mg/kg (Treatment 2) and when CSA was administered at 2.5 mg/kg concurrently with KTZ at 5 (Treatment 3) or 2.5 mg/kg (Treatment 4). We hypothesized that skin and blood CSA concentrations in Treatment 1 would not differ from those obtained with T3 or T4. ANIMALS: In a randomized cross-over study, six healthy research dogs received each of the treatments (Treatment 1, 2, 3 and 4) once daily for 7 days. METHODS: After the first, fourth and seventh dose for each treatment, a peak and trough skin punch biopsy sample and whole blood sample were collected and analysed with high-performance liquid chromatography-tandem mass spectrometry. Data were analysed using a repeated measures approach with PROC MIXED in SAS. Pairwise comparisons were performed with least squares means and Tukey-Kramer adjustment for multiple comparisons. RESULTS: Mean blood CSA concentrations in Treatment 1 were not different from those in Treatment 2 or 4, but were less than in Treatment 3. Mean skin CSA concentrations in Treatment 1 were greater than in Treatment 2, not different from those in Treatment 4, and less than those in Treatment 3. CONCLUSIONS AND CLINICAL IMPORTANCE: Administration of CSA and KTZ concurrently at 2.5 mg/kg each may be as effective as CSA alone at 5.0 mg/kg for treatment of canine atopic dermatitis.

Practical otic anatomy and physiology of the dog and cat.

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 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.

Primary secretory otitis media in Cavalier King Charles spaniels.

Primary secretory otitis media (PSOM) is a disease that has been described in the Cavalier King Charles spaniel (CKCS). A large, bulging pars flaccida identified on otoscopic examination confirms the diagnosis. However, in many CKCS with PSOM the pars flaccida is flat, and radiographic imaging is needed to confirm the diagnosis. Current treatment for PSOM includes performing a myringotomy into the caudal-ventral quadrant of the pars tensa with subsequent flushing of the mucus out of the bulla using a video otoscope. Repeat myringotomies and flushing of the middle ear are necessary to keep the middle ear free of mucus.

Epithelial migration on the canine tympanic membrane.

Epithelial migration (EM) is a process that serves as a self-cleaning and repair mechanism for the ear canal and tympanic membrane (TM). Epithelial migration has been evaluated in humans and several other species, but not in dogs. The objective of this study was to determine the rate and pattern of EM on the TM in clinically normal laboratory dogs. Eighteen dogs were anaesthetized, and three drops of waterproof drawing ink were placed on two sites of the pars tensa (PT) and one on the pars flaccida (PF). Images were recorded with a video otoscope and digital capture system. Each dog was evaluated and images were recorded every 6-8 days for four evaluations. Migration pattern analysis and EM rate calculation were performed with image-processing software. Descriptive statistics for EM rate (mean, SD, 95% confidence interval) were calculated for all ink-drop locations on the TM (PT1, PT2 and PF) at each time point. No significant differences in the mean EM rates were identified between right and left ears of the fox hounds breeds (beagle or fox hound), or locations PT1 and PT2. The mean overall EM rates (± SD) were 96.4 (± 43.1) and 225.4 (± 128.1) µm/day for the PT and PF, respectively. All ink drops moved outwards, the majority in a radial direction, from the original location to the periphery of the TM. The ink-drop placement method used in this study can be used in future studies to determine the EM rate of the canine TM.

Anatomy and physiology of the canine ear.

The canine ear consists of the pinna, external ear canal, middle ear and inner ear. The external ear is composed of auricular and annular cartilage. The auricular cartilage of the pinna becomes funnel shaped at the opening of the external ear canal. The vertical ear canal runs for about 1 inch, then forms the horizontal ear canal, which is composed of auricular and annular cartilage. The middle ear consists of an air-filled tympanic cavity, three auditory ossicles, and tympanic membrane. The tympanic membrane is a semitransparent membrane divided into the pars flaccida and pars tensa. The tympanic cavity consists of a small epitympanic recess, a large ventral bulla and the tympanic bulla proper. On the medial wall of the tympanic cavity is the promontory, which houses the cochlea. The cochlear (round) window is located in the caudolateral portion of the promontory, covered by a thin membrane. The vestibular (oval) window is located on the dorsolateral surface of the promontory, covered by a thin diaphragm over which the footplate of the stapes is attached. The auditory tube is a short canal that extends from the nasopharynx to the rostral portion of the tympanic cavity proper. The auditory ossicles are the bones that transmit and amplify air vibrations from the tympanic membrane to the inner ear. The inner ear is housed in a bony labyrinth in the petrous portion of the temporal bone. The bony labyrinth contains the membranous labyrinth with its sensory organs responsible for hearing and balance.

Evaluation of Clinical Laboratory Standards Institute interpretive criteria for methicillin-resistant Staphylococcus pseudintermedius isolated from dogs.

The Clinical and Laboratory Standards Institute published in 2008 new interpretive criteria for the identification of methicillin resistance in staphylococci isolated from animals. The sensitivity of the 2008 interpretive criteria for mecA gene-positive Staphylococcus pseudintermedius, compared with the previous criteria of 2004, was investigated. Thirty clinical isolates of methicillin-resistant S. pseudintermedius from dogs were used. The presence of the mecA gene was determined by polymerase chain reaction. The minimum inhibitory concentration for oxacillin was determined by broth microdilution. The 2008 breakpoint of >or=4 microg/ml for methicillin resistance resulted in a diagnostic sensitivity of 73.3% (22/30). The 2004 breakpoint guideline of >or=0.5 microg/ml resulted in a diagnostic sensitivity of 97% (29/30). For oxacillin disk diffusion, the 2008 interpretive criterion of