Comparison of two ear cytological collection techniques in dogs with otitis externa.

BACKGROUND: Canine otitis externa is a common disease. Cytological evaluation of otic exudate is a useful diagnostic test to direct and monitor treatment for otitis externa. One method of collecting ear cytological specimens utilizes a cotton-tipped swab inserted into the vertical ear canal. A proposed alternative method is to aspirate exudate from the deep horizontal canal using a rubber tube. HYPOTHESIS/OBJECTIVES: To compare cytological findings between two different collection techniques by evaluating the numbers of bacteria, Malassezia yeast and inflammatory cells. ANIMALS: Thirty client-owned dogs with otitis externa. METHODS AND MATERIALS: A prospective, randomized, blinded comparison study. Ear canals from each dog were sampled using cotton swab and rubber tube. Ear cytological preparations were evaluated independently by two investigators for polymorphonuclear leucocytes (PMN), monocytes/lymphocytes, macrophages, yeast, intracellular (IC) cocci, extracellular (EC) cocci, IC bacilli and EC bacilli. RESULTS: A paired Student's t-test was used to compare the two techniques. The inter-investigator reliability for PMN, EC bacilli and yeast was good, and for EC cocci was moderate. There were significantly higher numbers of PMNs obtained by the tube method (P = 0.0024) than by the cotton swab method. There were no statistically significant differences between cotton swab and rubber tube methods for monocytes/lymphocytes (P = 0.7780), macrophages (P = 0.1751), EC cocci (P = 0.1262), EC bacilli (P = 0.1162), yeast (P = 0.5371), IC cocci (P = 0.6606) or IC bacilli (P = 0.6761). The technique was well tolerated. CONCLUSION: An alternative ear cytological collection technique was identified which enables sampling of the deep horizontal canal.

Reproducibility of a quantitative cutaneous cytological technique.

BACKGROUND: Cutaneous cytology is a valuable tool for diagnosis of canine superficial pyoderma. Current published reproducible techniques are semiquantitative. HYPOTHESIS/OBJECTIVES: The aim of this study was to evaluate the reproducibility of a quantitative method for skin surface cytology in dogs with superficial pyoderma. ANIMALS: Impression smears were collected from five normal dogs and 20 dogs with clinical and cytological evidence of superficial pyoderma. METHODS: Four investigators evaluated 10 oil immersion fields (OIF) on 25 slides, selecting fields with inflammatory cells, nuclear streaming and or keratinocytes under ×10 magnification. Investigators repeated blinded evaluations of all slides at least twice. For each OIF, polymorphonuclear leukocytes (PMNs), intracellular (IC) cocci, extracellular (EC) cocci, IC rods, EC rods and yeast were quantified. Nuclear streaming was scored as present or absent. For each parameter, within-reader and between-reader agreements were expressed by the intraclass correlation (ICC) value (≤0.20 poor, 0.21-0.40 fair, 0.41-0.60 moderate, 0.61-0.80 good and 0.81-1.00 excellent) or kappa statistic (κ). RESULTS: Reproducible parameters included: PMNs (ICC = 0.58), nuclear streaming (ICC = 0.68), EC cocci (ICC = 0.64) and IC cocci (ICC = 0.32). When qualified as present or absent, within-reader κ for IC cocci was 0.71. The method demonstrated 93% sensitivity in identifying dogs with superficial pyoderma and 51% specificity in identifying normal dogs according to established criteria. However, if criteria for normal dogs were limited to the absence of PMNs and IC bacteria, sensitivity of 64% and specificity of 98% were demonstrated. CONCLUSIONS AND CLINICAL IMPORTANCE: For several parameters, including PMNs, nuclear streaming, EC cocci and IC cocci, a reproducible, quantitative cytological technique was identified.

Age- and breed-matched retrospective cohort study of malignancies and benign skin masses in 660 dogs with allergic dermatitis treated long-term with versus without oclacitinib.

OBJECTIVE: To compare the cumulative incidences of malignancies and benign skin masses and the mean age at death or euthanasia in dogs with allergic dermatitis treated long-term with versus without oclacitinib. ANIMALS: 660 client-owned dogs. PROCEDURES: Medical records were searched to identify dogs with allergic dermatitis treated for ≥ 6 months with oclacitinib (exposed dogs; n = 339) versus other available treatments before the introduction of oclacitinib (nonexposed dogs; 321) and with ≥ 24 months of follow-up information available. Nonexposed dogs were age and breed matched with 321 of the exposed dogs; data for the remained 18 exposed dogs were included in statistical analyses. Results for cumulative incidences of malignancies and other variables were compared between groups, and the effect of daily maintenance dosage of oclacitinib on cumulative incidences of malignancies and other skin masses was evaluated within the exposed group. RESULTS: No meaningful differences were detected in the cumulative incidences of malignancies and overall skin masses or the mean age at death or euthanasia for dogs in the exposed group (16.5% [56/339], 56.6% [192/339], and 11.2 years [n = 80], respectively) versus the nonexposed group (12.8% [41/321], 58.3% [187/321], and 11.8 years [71], respectively). There was no association identified between daily maintenance dosage of oclacitinib and odds of malignancy or benign skin masses for dogs in the exposed group. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that long-term treatment with oclacitinib did not pose additional risk for malignancy in dogs; however, veterinarians should continue to observe FDA-approved label warning and precaution statements for oclacitinib and regularly screen for neoplasia in dogs with allergic skin disease treated with or without oclacitinib.

Electrochemical pinning of the Fermi level: mediation of photoluminescence from gallium nitride and zinc oxide.

Charge transfer between diamond and an electrochemical redox couple in an adsorbed water film has recently been shown to pin the Fermi level in hydrogen-terminated diamond. Here we show that this effect is a more general phenomenon and influences the properties of other semiconductors when the band lineup between the ambient and electronic states in the semiconductor is appropriate. We find that the luminescent intensities from GaN and ZnO change in different, but predictable, ways when exposed to HCl and NH3 vapors in humid air. The effect is reversible and has been observed on single crystals, nanowires, flakes, and powders. These observations are explained by electron exchange between the oxygen electrochemical redox couple in an adsorbed water film and electronic states in the semiconductor. This effect can take place in parallel with other processes such as defect formation, chemisorption, and surface reconstruction and may play an important, but previously unrecognized, role when electronic and optical measurements are made in air.

Breed variations in histopathologic features of chronic severe otitis externa in dogs: 80 cases (1995-2001).

OBJECTIVE: To compare pathologic changes of the horizontal ear canal associated with chronic severe otitis externa between Cocker Spaniels and dogs of other breeds. DESIGN: Retrospective study. ANIMALS: 80 dogs with severe otitis externa that required total ear canal ablation with lateral bulla osteotomy. PROCEDURE: Medical records were reviewed for breed, sex, and age at time of surgery. Histologic specimens from the horizontal ear canal were evaluated by a single examiner for overall tissue response pattern and scored for sebaceous gland hyperplasia, ceruminous gland hyperplasia, ceruminous gland ectasia, fibrosis, pigment-laden macrophages, and osseous metaplasia. RESULTS: 48 of 80 (60%) dogs were Cocker Spaniels. Thirty-five of 48 (72.9%) Cocker Spaniels had a predominately ceruminous tissue response pattern; only 9 of 32 (28.1 %) dogs of other breeds had the same pattern. Other breeds most commonly had a pattern dominated by fibrosis (n = 13 [40.6%]); fibrosis was the predominant pattern in only 4 of 48 (8.3%) Cocker Spaniels. Discriminant analysis and K-means clustering of 4 histopathologic criteria correctly classified 75% of the dogs as Cocker Spaniels or all other breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Cocker Spaniels are at increased risk for chronic severe otitis externa requiring total ear canal ablation with lateral bulla osteotomy, indicating that earlier and more aggressive management of the primary otitis externa and secondary inflammation is warranted in this breed. Cocker Spaniels with chronic severe otitis externa have distinct differences in pathologic characteristics of the horizontal ear canal, compared with other breeds.

Otic cytology in health and disease.

Accurate characterization of the primary cause and perpetuating factors is essential for successful management of ear disease in dogs and cats. Cytology is a simple, rapid, and practical diagnostic test that should be performed routinely on any and all patients presented for clinical signs consistent with otitis externa. In combination with clinical signs, otoscopic evaluation, and diagnostic testing of primary disease, serial cytology enhances the ability of veterinarians to diagnose secondary infections, monitor progression of disease, evaluate response to therapy, and make appropriate management decisions. Cytologic specimens should be evaluated for the presence, numbers, and characteristics of three key features: yeast, bacteria, and leukocytes. More than five yeast organisms or more than 25 bacteria per high-powered field is suggestive of significant microbial activity warranting therapeutic intervention. The presence of leukocytes, particularly with phagocytized bacteria, indicates "true infection" rather than overgrowth; if suppurative discharge is present, systemic therapy is needed. Cytology combined with culture and susceptibility is the best method for identification of bacterial overgrowth and infection; however, if only one test can be performed, always choose cytology. Culture results assist in the selection of appropriate antibiotic therapy, but cytology determines whether systemic antibiotics are indicated, which organisms are most significant, and when therapy can be discontinued.

Variability of laboratory identification and antibiotic susceptibility reporting of Pseudomonas spp. isolates from dogs with chronic otitis externa.

The purpose of this study was to evaluate interlaboratory variation in isolation and antibiotic susceptibility pattern of Pseudomonas spp. as reported to veterinarians for cases of canine chronic bacterial otitis externa. Twenty-six dogs with unilateral or bilateral bacterial otitis externa from multiple referral practices were included in this prospective study. Triplicate samples collected simultaneously from the same location in the external ear canal were randomly submitted to three laboratories for culture and susceptibility testing. Pseudomonas spp. were isolated from 18 of 34 (53%) ears. All three laboratories agreed on the presence of Pseudomonas spp. in 15 (83.3%) ears sampled. However, two laboratories agreed on two (11.1%) occasions, and on one occasion (5.5%) Pseudomonas spp. were identified in only one laboratory. Minimum inhibitory concentration (MIC) susceptibilities to 11 antibiotics were compared between laboratories B and C. Using laboratory-defined susceptibility of sensitive (S), intermediate (I) and resistant (R), none of the 16 Pseudomonas spp. with MIC data reported had identical patterns of antibiotic susceptibility. Agreement in susceptibility to individual antibiotics was observed in 13 of 16 (81%) occasions for amikacin and gentamicin, 10 of 16 (63%) occasions for ticarcillin, and nine of 16 (56%) for enrofloxacin. These results indicate that Pseudomonas spp. were identified by all three laboratories chosen for this study in 83% of the time. Moreover, antibiotic susceptibility patterns and MIC values reported to veterinarians may not agree between laboratories. Veterinarians should interpret bacterial culture and susceptibility results with multiple caveats including variability between laboratories.

Charge transfer equilibria between diamond and an aqueous oxygen electrochemical redox couple.

Undoped, high-quality diamond is, under almost all circumstances, one of the best insulators known. However, diamond covered with chemically bound hydrogen shows a pronounced conductivity when exposed to air. This conductivity arises from positive-charge carriers (holes) and is confined to a narrow near-surface region. Although several explanations have been proposed, none has received wide acceptance, and the mechanism remains controversial. Here, we report the interactions of hydrogen-terminated, macroscopic diamonds and diamond powders with aqueous solutions of controlled pH and oxygen concentration. We show that electrons transfer between the diamond and an electrochemical reduction/oxidation couple involving oxygen. This charge transfer is responsible for the surface conductivity and also influences contact angles and zeta potentials. The effect is not confined to diamond and may play a previously unrecognized role in other disparate systems.