• Journal of Veterinary Clinics
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• v.37 no.1
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• pp.1-8
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• 2020

Canine otitis externa is a common disorder in small animal practice with prevalence up to 20%. In a large percentage of cases, canine otitis externa is a chronic and recurrent disease also associated with drug-resistant bacteria that is difficult to treat with traditional antibiotics. Photodynamic therapy (PDT) is a new strategy to exterminate pathogenic microorganisms such as bacteria and fungi. The purpose of this study was to investigate the effectiveness of photodynamic therapy against canine otitis externa using three photosensitizer (PS); 5-Aminolevulinic acid (5-ALA) and Methyl aminolevulinic acid (MAL) with semiconductor laser diode (SLD, 635nm of wave length), Chlorophyll-lipoid complex (CLC) with light-emitting diode (LED, 660nm of wave length). After PDT, dogs showed improved Otitis Index Score (OTIS) in swelling, exudate, odor, and pain. A result of the cytology test revealed decrease of bacteria and malassezia count in the oil immersion field and colony forming units count. PDT was effective as a bacteriocide of methicillin-resistant Staphylococcus pseudintermedius (MRSP) and a fungicide of Malassezia pachydermatis. MAL and 5-ALA were more effective PS against canine otitis externa than CLC. These results suggest that PDT is a new strategy to exterminate pathogenic microorganisms such as bacteria and fungi. PDT can be considered as a new therapeutic approach for canine recurrent otitis externa and a countermeasure to drug resistance that is a disadvantage of traditional antibiotic and antifungal therapy.

• Journal of Veterinary Clinics
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• v.31 no.1
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• pp.66-69
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• 2014

Photodynamic therapy (PDT) is an effective method for infectious disease, but as yet, no clinical trial on otitis externa has been conducted in animals. This report describes 4 cases of PDT treatment on severe otitis externa in canine. Four canines were treated with various concentrations of 5-aminolevulinic acid hydrochloride (5-ALA) and with various J (second ${\times}$ power) and irradiated by light-emitting diode light source at 635 nm, respectively. After the PDT applications, canines incubated in the dark for 5 or 6 hr. All patients showed clinical resolution of otitis externa after PDT treatment at the dose of 0.16~0.3 g ALA and J (54~162 $J/cm^2$). On the basis of these findings, PDT can be considered to be a new therapeutic approach to severe otitis externa in canine.

• Journal of Veterinary Science
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• v.24 no.6
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• pp.85.1-85.13
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• 2023

Background: A recent increase in the occurrence of canine skin and soft tissue infections, including otitis externa and pyoderma, caused by antimicrobial-resistant Staphylococcus pseudintermedius and S. schleiferi has become a significant public and veterinary health issues. Objective: We investigated the virulence potentials associated with the occurrence of canine otitis externa in S. pseudintermedius and S. schleiferi. Methods: In this study, the prevalence of genes encoding leukocidins, exfoliative toxins, and staphylococcal enterotoxins (SEs) was investigated using previously characterized S. pseudintermedius (n = 26) and S. schleiferi (n = 19) isolates derived from canine otitis externa. Susceptibility to cathelicidins (K9CATH and PMAP-36) and hydrogen peroxide (H₂O₂) was also examined in both staphylococcal species. Results: A high prevalence of genes encoding leukocidins (lukS/F-I, lukS1/F1-S, and lukS2/F2-S), exfoliative toxins (siet, expB, and sset), and SEs was identified in both S. pseudintermedius and S. schleiferi isolates. Notably, S. pseudintermedius isolates possessed higher number of SE genes, especially newer SE genes, than S. schleiferi isolates harboring egc clusters. Although no significant differences in susceptibility to K9CATH and H₂O₂ were observed between the two isolate groups, S. pseudintermedius isolates exhibited enhanced resistance to PMAP-36 compared to S. schleiferi isolates. Conclusions: These findings suggest that high a prevalence of various toxin genes together with enhanced resistance to cathelicidins may contribute to the pathogenicity of S. pseudintermedius and S. schleiferi in canine cutaneous infections.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.566-574
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• 1999

This study was conducted to examine the outbreak rate and the causative agents of otitis externa in 26 dogs (49 ears ; 23 dogs = bilateral, 3 dogs = unilateral), and the normal microfloras of external ear canal in 68 dogs(133 ears ; 65 dogs = bilateral, 3 dogs = unilateral ) in Taegu, 1997. The breed, living environment, sex, age and season distribution of otitic dogs were as follows : Dogs with erect and hairy ears(42.3%), pendulous and hairy ears(38.5%), indoor(92.3%), female(65.4%) and below one year old(38.5%) were more prevalent. According to season, otitis externa was mainly occurred between July and October. The major causative agents of canine otitis externa were Malassezia pachydermatis (32.7%), Staphylococcus aureus (26.5%) and S intermedius (16.3%). In the microorganism isolated 39 otitic ear canals, single infection was 53.8% and mixed infection was 46.2%. The normal microfloras of canine external ear canal were fungi including M pachydermatis, Aspergillus spp, Microsporum canis, Alternaria spp, Verticillium spp and Yeast, and bacteria including Staphylococcus spp(10 species including S xylosus), Bacillus spp, Corynebacterium spp, Listeria spp, Actinomyces pyogenes and Escherichia coli. No growth was 34.6%.

• Korean Journal of Veterinary Research
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• v.49 no.2
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• pp.173-177
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• 2009

This study examined the efficacy of apitoxin for the treatment of otitis externa in dogs. Ten dogs with otitis externa were allocated randomly to two groups. The control group was treated with the susceptible antibiotics and the experimental group was injected with apitoxin into the tragus subcutaneously. There were no significant differences in the clinical scores, blood WBC counts and neutrophil/lymphocyte ratios between the control and experimental groups. By 2 weeks, the bacterial cell counts were significantly lower in the experimental group than the control (p < 0.05). No adverse reactions were observed in any of the dogs during the study. This suggests that a topical injection of apitoxin is an effective treatment for otitis externa in dogs.

• Journal of Veterinary Science
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• v.21 no.1
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• pp.11.1-11.7
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• 2020

The increase in canine skin and soft tissue infections, such as pyoderma and otitis, caused by Staphylococcus schleiferi strains, is of significant zoonotic concern. In this study, we report the first complete genome sequence for a methicillin-resistant clinical isolate of S. schleiferi (MRSS) designated as SS4, obtained from a dog with otitis externa, in Korea. The genome of SS4 strain was of 2,539,409 bp and presented high G+C content ratio (35.90%) with no plasmid. Comparative analysis of SS4 genome revealed that it is closely related to 2142-05 and 5909-02 strains isolated from the canine skin infections in the USA.

• Korean Journal of Veterinary Research
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• v.61 no.2
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• pp.16.1-16.6
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• 2021

Pseudomonas aeruginosa is one of the most common pathogenic species associated with canine otitis externa (OE). Their resilience is achieved by forming a biofilm, which allows these bacteria to evade even the harshest of treatments. This study evaluated the in vitro synergistic efficacy of N-acetylcysteine (NAC) with different antimicrobial agents against P. aeruginosa isolated from dogs with OE to develop an effective treatment against P. aeruginosa. The antimicrobial activity was evaluated by the minimum inhibitory concentration test using the microdilution method. The efficacy of antibiofilm formation was evaluated using a crystal violet stain method. The treatment solutions included NAC alone, and in synergy with enrofloxacin, polymyxin B, and gentamicin. NAC alone exhibited antimicrobial and antibiofilm abilities. On the other hand, the combination of NAC and the antibiotics did not show any significant synergistic effects against P. aeruginosa.

• Korean Journal of Veterinary Research
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• v.61 no.4
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• pp.37.1-37.6
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• 2021

This study evaluated the efficacy of a new, single-dose otic solution combining florfenicol, terbinafine, and mometasone furoate for the treatment of canine otitis externa (OE) in vitro and in vivo. Forty-one client-owned dogs with OE were included in the study and divided into a treatment group that received the test solution and a negative control group that received a normal saline solution. On day 0, the dogs were treated either with the test or the control solution and evaluated over 30 days. Clinical efficacy was evaluated by clinical signs and cytological organism counts. In vitro antimicrobial susceptibility was evaluated by the minimum inhibitory concentration (MIC). After treatment with the test solution, clinical signs continuously decreased and cytological scores were significantly reduced. The results of MIC testing showed that the test solution was potent against the common pathogenic causes of canine OE. In this study, the most common causative pathogens were Staphylococcus pseudintermedius, Pseudomonas spp. and Malassezia pachydermatis. No issues related to safety were identified. Based on these results, this new ototopical drug can be used as first line treatment for canine OE.

• Korean Journal of Veterinary Research
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• v.49 no.1
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• pp.85-89
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• 2009

This study examined the therapeutic effects of aromatherapy for the treatment of otitis externa in dogs. Eleven dogs with otitis externa were examined. The control group (5 dogs) was treated with susceptible antibiotics, and the experimental group (6 dogs) was treated with aroma-oil applied topically to the ear canal. The aroma-oil contained 10 ml sweet almond oil, 0.3 ml bergamot oil, 0.2 ml lavender oil, 0.1 ml tea tree oil and 0.1 ml roman chamomile oil. The blended aroma-oil (0.1 ml) was applied to the ear canal twice daily for 2 weeks. The authors examined the changes in the clinical signs, bacterial count in discharges, total WBC count and neutrophil/lymphocyte ratios in the two groups. The bacterial cell counts in the experimental group were significantly lower at one (p < 0.01) and two weeks (p < 0.05) after treatment than the control group. These results suggest that aromatherapy is an effective and practical treatment for otitis externa in dogs.

• Journal of Veterinary Clinics
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• v.21 no.2
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• pp.149-153
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• 2004

This study was to determine the procedure for ultrasonographic imaging of the canine external ear canal(ECC). By infusion of warm saline solution into the ear canal, a real-time B mode ultrasonographic examination of the ECC was performed in five healthy Beagle dogs and two dogs with severe otitis externa. The ultrasonography was very useful to detect the structures of the ECC and the tympanic membrane. An 11 NHz linear probe was permitted to assess an anechoic lumen of the ECC and a hyperechoic cartilage surrounding the ear canal. In two dogs with otitis externa, it could be assessed the ECC with ultrasonography without ear cleansing. A lumen of the ECC was irregular and a cerumen could be seen, but edematous inflammatory changes of the ECC could not be identified. The results suggest that ultrasonography of the ECC with an 11 NHz linear probe after infusing the saline solution into the ear canal may be an accurate, non-invasive, rapid, and widely available method for assessment of the ear canal diseases such as otitis externa, polyp, stenosis, hyperplasia, and foreign body in dogs.