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.

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.

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.

In vitro activity of an ear rinse containing tromethamine, EDTA, benzyl alcohol and 0.1% ketoconazole on Malassezia organisms from dogs with otitis externa.

The purpose of this study was to evaluate the in vitro activity of an ear rinse containing tromethamine, EDTA, benzyl alcohol and 0.1% ketoconazole in purified water on Malassezia organisms from dogs with otitis externa. Malassezia organisms were collected from ear swab samples from the external ear canal of 19 dogs with otitis externa plus one control strain of Malassezia pachydermatis. Three test solutions were evaluated: ER (EDTA, tromethamine, benzyl alcohol), ER + keto (EDTA, tromethamine, benzyl alcohol, ketoconazole), and H2O (purified water). Ten-millilitre aliquots of each test solution was transferred into 20 tubes and inoculated with one of the isolates (1 tube per isolate: 19 clinical and 1 control strain). Samples were retrieved from each tube at five time points (0, 15, 30, 45 and 60 min), transferred to Petri dishes, mixed with Sabouraud dextrose agar supplemented with 0.5% Tween 80 and incubated. Following incubation, the plates were examined for growth and colonies counted as colony-forming units per millilitre. The data were analysed using a repeated measures analysis, with pair-wise comparisons of solution-time combinations. There was a significant reduction in Malassezia growth in ER + keto at all time points (P < 0.0001) compared to time zero. Neither ER nor H2O had any effect on the growth of Malassezia. ER + keto was significantly more effective in reducing Malassezia growth (P < 0.0001) at all time points compared to both ER and H2O. ER + keto may be useful in the treatment of Malassezia otitis externa. Future studies should be performed to evaluate the in vivo efficacy of ER + keto as treatment for otic infections caused by Malassezia.

Evaluation of a local anesthetic delivery system for the postoperative analgesic management of canine total ear canal ablation--a randomized, controlled, double-blinded study.

OBJECTIVE: To determine if a constant rate local anesthetic delivery system is more effective than continuous intravenous (IV) morphine infusion for postoperative analgesia. ANIMALS: Twenty client-owned dogs undergoing total ear canal ablation. METHODS: Dogs were randomly assigned to the lidocaine group (LID) or the morphine group (MOR). The LID group received a constant rate infusion of lidocaine locally and a continuous IV infusion of saline, while the MOR group received a constant rate infusion of saline locally and a continuous IV infusion of morphine. The primary investigator evaluated each patient and determined a hospital behavior score, anesthesia recovery score, preoperative pain score, and serial postoperative pain and sedation scores over 38 hours. Pain and sedation observations were videotaped and scored by three additional evaluators. Evaluators were blinded to treatment assignments. RESULTS: There were no significant differences in age, weight, hospital behavior scores or anesthesia recovery scores. The primary investigator's pain scores were not significantly different, but sedation scores were significantly lower for the LID group. Sedation and pain scores by the video evaluators were not significantly different between groups. Kappa agreement between observers was poor, but better agreement was noted between sedation scores than pain scores. Drug-related complications were significantly lower in the LID group (n = 0) compared with the MOR group (n = 5). Wound complications were not significantly different (LID = 4, MOR = 4). Intravenous delivery complications occurred in 12 (60%) patients. Local delivery complications occurred in five (25%) dogs. Delivery complications were not significantly different between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous incisional lidocaine delivery was an equipotent and viable method of providing postoperative analgesia compared with IV morphine. Lidocaine delivery resulted in a trend toward lower pain scores, significantly lower sedation scores, and no dogs requiring analgesic rescue. Wound complications secondary to local infusion were minor and self-limiting. Drug-related complications occurred only in the MOR group.

Ciprofloxacin as a representative of disk diffusion in vitro susceptibility of enrofloxacin for bacterial organisms from the middle-ear tissue of dogs with end-stage otitis externa.

The purposes of this study were to determine whether ciprofloxacin disk diffusion susceptibility test (DDT) results could be used to assess the in vitro susceptibility of otic bacterial organisms to enrofloxacin and to determine the effect of concurrent enrofloxacin administration on the DDT results for enrofloxacin and ciprofloxacin. Thirty dogs with end-stage otitis externa undergoing unilateral total ear canal ablation were enrolled. The dogs were randomized to one of four enrofloxacin-treatment groups or to the control group. Each dog in the treatment groups received two intravenous doses of enrofloxacin prior to surgical removal of the middle-ear tissue while the control group did not receive any enrofloxacin. One dog was excluded from the study as no middle-ear tissue was removed during surgery. Twenty-four dogs were in the enrofloxacin-treatment groups and five dogs were in the control group. In 12 of 29 dogs (41.4%), 14 of 82 (17.1%) of bacteria had discrepancies in DDT results for enrofloxacin and ciprofloxacin. Discrepancies between the control group and treatment groups were not significantly different even though the percentage of discrepancies for the combined treatment group was 19.4% compared to 6.7% for the control group. In this study, ciprofloxacin DDT results were not an accurate indicator of the in vitro susceptibility of enrofloxacin for bacteria isolated from the middle-ear tissue of dogs with end-stage otitis.