Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats Clinical Consensus Guidelines of the World Association for Veterinary Dermatology.

BACKGROUND: The genus Malassezia is comprised of a group of lipophilic yeasts that have evolved as skin commensals and opportunistic cutaneous pathogens of a variety of mammals and birds. OBJECTIVES: The objective of this document is to provide the veterinary community and other interested parties with current information on the ecology, pathophysiology, diagnosis, treatment and prevention of skin diseases associated with Malassezia yeasts in dogs and cats. METHODS AND MATERIAL: The authors served as a Guideline Panel (GP) and reviewed the literature available prior to October 2018. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) Clinical Consensus Guideline committee provided guidance and oversight for this process. The document was presented at two international meetings of veterinary dermatology societies and one international mycology workshop; it was made available for comment on the WAVD website for a period of six months. Comments were shared with the GP electronically and responses incorporated into the final document. CONCLUSIONS AND CLINICAL IMPORTANCE: There has been a remarkable expansion of knowledge on Malassezia yeasts and their role in animal disease, particularly since the early 1990's. Malassezia dermatitis in dogs and cats has evolved from a disease of obscurity and controversy on its existence, to now being a routine diagnosis in general veterinary practice. Clinical signs are well recognised and diagnostic approaches are well developed. A range of topical and systemic therapies is known to be effective, especially when predisposing factors are identified and corrected.

In vitro antimicrobial activity of narasin and monensin in combination with adjuvants against pathogens associated with canine otitis externa.

BACKGROUND: The emergence of antimicrobial resistance represents a serious human and animal health risk. Good antimicrobial stewardship is essential to prolong the lifespan of existing antibiotics, and new strategies are required to combat infections in man and animals. HYPOTHESIS/OBJECTIVES: To determine the in vitro interaction of ionophores (narasin or monensin) with antimicrobial adjuvants (N-acetylcysteine (NAC), Tris-EDTA or disodium EDTA) against bacterial strains representing pathogens associated with canine otitis externa (OE). ANIMAL/ISOLATES: American Type Culture Collection (ATCC) strains Staphylococcus aureus 29213, Pseudomonas aeruginosa 27853 and P. aeruginosa biofilm producer PAO1, and a clinical isolate of Proteus mirabilis from a case of canine OE were tested. METHODS AND MATERIALS: A 2D microdilution checkerboard method was used, allowing calculation of fractional inhibitory concentration index (FICI), dose reduction index (DRI) and plotting of isobolograms. RESULTS: The combination of narasin with either Tris-EDTA or disodium EDTA produced additive effects (FICI = 0.75) against P. aeruginosa ATCC 27853 and P. aeruginosa biofilm producer ATCC PAO1. An additive effect (FICI = 0.53-0.75) was found against S. aureus ATCC 29213 when narasin or monensin were combined with NAC. The highest DRI (32-fold) was found with monensin/NAC where the MIC of monensin was reduced from 4 to 0.125 µg/mL. CONCLUSIONS AND CLINICAL IMPORTANCE: The combination of narasin with Tris-EDTA or disodium EDTA is a promising strategy to inhibit the intrinsic resistance elements of Gram-negative bacteria. These novel combinations potentially could be useful as a multimodal approach to treat mixed infections in canine OE.

Biofilm production by pathogens associated with canine otitis externa, and the antibiofilm activity of ionophores and antimicrobial adjuvants.

Otitis externa (OE) is a frequently reported disorder in dogs associated with secondary infections by Staphylococcus, Pseudomonas and yeast pathogens. The presence of biofilms may play an important role in the resistance of otic pathogens to antimicrobial agents. Biofilm production of twenty Staphylococcus pseudintermedius and twenty Pseudomonas aeruginosa canine otic isolates was determined quantitatively using a microtiter plate assay, and each isolate was classified as a strong, moderate, weak or nonbiofilm producer. Minimum biofilm eradication concentration (MBEC) of two ionophores (narasin and monensin) and three adjuvants (N-acetylcysteine (NAC), Tris-EDTA and disodium EDTA) were investigated spectrophotometrically (OD570nm ) and quantitatively (CFU/ml) against selected Staphylococcus and Pseudomonas biofilm cultures. Concurrently, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of planktonic cultures were assessed. 16/20 of the S. pseudintermedius clinical isolates were weak biofilm producers. 19/20 P. aeruginosa clinical isolates produced biofilms and were distributed almost equally as weak, moderate and strong biofilm producers. While significant antibiofilm activity was observed, no MBEC was achieved with narasin or monensin. The MBEC for NAC ranged from 5,000-10,000 µg/ml and from 20,000-80,000 µg/ml against S. pseudintermedius and P. aeruginosa, respectively. Tris-EDTA eradicated P. aeruginosa biofilms at concentrations ranging from 6,000/1,900 to 12,000/3,800 µg/ml. The MBEC was up to 16-fold and eightfold higher than the MIC/MBC of NAC and Tris-EDTA, respectively. Disodium EDTA reduced biofilm growth of both strains at concentrations of 470 µg/ml and higher. It can be concluded that biofilm production is common in pathogens associated with canine OE. NAC and Tris-EDTA are effective antibiofilm agents in vitro that could be considered for the treatment of biofilm-associated OE in dogs.

In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa.

BACKGROUND: An antibiotic adjuvant is a chemical substance used to modify or augment the effectiveness of primary antimicrobial agents against drug-resistant micro-organisms. Its use provides an alternative approach to address the global issue of antimicrobial resistance and enhance antimicrobial stewardship. HYPOTHESIS/OBJECTIVES: To determine the antimicrobial activity of a panel of potential antimicrobial adjuvants against common pathogens associated with canine otitis externa (OE). ANIMALS/ISOLATES: A number of type strains and clinical isolates (n = 110) from canine OE were tested including Staphylococcus pseudintermedius, ß-haemolytic Streptococcus spp., Pseudomonas aeruginosa, Proteus mirabilis and Malassezia pachydermatis. METHODS AND MATERIALS: Antimicrobial activities of monolaurin, monocaprin, N-acetylcysteine (NAC), polymyxin B nonapeptide, Tris-EDTA, Tris-HCL and disodium EDTA were tested using microdilution methodology according to CLSI guidelines. RESULTS: N-acetylcysteine, Tris-EDTA and disodium EDTA had antimicrobial activity against both type strains and otic pathogens. The other adjuvants tested had limited to no efficacy. NAC had a minimal inhibitory concentration (MIC) range of 2,500-10,000 µg/mL for the various organisms. Pseudomonas aeruginosa isolates were eight times more susceptible to disodium EDTA in the presence of Tris-HCL in comparison to disodium EDTA alone. Malassezia pachydermatis isolates were most susceptible to Tris-EDTA (MIC90  = 190/60 µg/mL) and disodium EDTA (MIC90  = 120 µg/mL). CONCLUSIONS AND CLINICAL RELEVANCE: N-acetylcysteine, Tris-EDTA and disodium EDTA have intrinsic antimicrobial activity and represent promising adjuvants that could be used to enhance the efficacy of existing antibiotics against Gram-negative and multidrug-resistant bacterial infections. These agents could be combined with other antimicrobial agents in a multimodal approach for mixed ear infections in dogs.

Development of a core outcome set for therapeutic clinical trials enrolling dogs with atopic dermatitis (COSCAD'18).

BACKGROUND: For decades, the efficacy of interventions in clinical trials enrolling dogs with atopic dermatitis (AD) relied on heterogeneous evaluations of skin lesions and pruritus using unvalidated tools. Although some instruments for clinical signs were validated later, there was little impact on standardizing outcome measures resulting in difficulties in comparing treatment efficacy between trials and impeding meta-analyses. RESULTS: Participants in the Outcome Measures subcommittee of the International Committee of Allergic Diseases of Animals (ICADA) collaborated for two years to develop a core outcome set (COS) for canine AD, the COSCAD. This project involved several steps, constantly-re-assessed during online exchanges, to define the scope of this COS, to identify the relevant stakeholders, the domains to be evaluated, the instruments available for measuring agreed-upon domains and how to express outcome measures. This COSCAD'18 was designed principally for therapeutic-but not preventive or proactive-clinical trials enrolling dogs with chronic, nonseasonal (perennial), moderate-to-severe AD. Selected domains were skin lesions, pruritus manifestations and perception of treatment efficacy. Instruments to evaluate these domains were the CADESI4 or CADLI, the 10-point pruritus visual analog scale (PVAS10) and the Owner Global Assessment of Treatment Efficacy (OGATE), respectively. The COSCAD'18 has three outcome measures: the percentages of dogs with veterinarian-assessed skin lesions or owner-rated pruritus manifestation scores in the range of normal dogs or those with mild AD; the third is a good-to-excellent global assessment by the pet owners of their perception of treatment efficacy. Importantly, this COSCAD'18 is not meant to represent the sole-or primary-outcome measures evaluated in a trial; authors are always free to add any others, which they deem will best assess the efficacy of tested interventions. Benchmarks to define a threshold for treatment success were not set, as what constitutes a clinically-relevant therapeutic efficacy is expected to vary greatly depending interventions. CONCLUSIONS: This COSCAD'18 should help veterinarians and owners compare the benefits of treatments in future trials. This COS should also facilitate the combination of trial results in future systematic reviews, thereby producing more reliable summary estimates of treatment effects and enhancing evidence-based veterinary dermatology.

In vitro efficacy of a honey-based gel against canine clinical isolates of Staphylococcus pseudintermedius and Malassezia pachydermatis.

BACKGROUND: Staphylococcus pseudintermedius and Malassezia pachydermatis are important agents in canine pyoderma and otitis. HYPOTHESIS/OBJECTIVES: Determine the in vitro efficacy of a honey-based gel (HBO) against meticillin-susceptible S. pseudintermedius (MSSP), meticillin-resistant S. pseudintermedius (MRSP) and M. pachydermatis, by minimum bactericidal concentration (MBC), minimum fungicidal concentration (MFC) and time-kill assay (TKA). Efficacy of the product's honey component (HO) also was evaluated. METHODS: Sixty S. pseudintermedius and 10 M. pachydermatis canine isolates were selected. All isolates were tested against serial dilutions of an HBO containing 40% HO (40%, 20%, 10%, 5% and 2.5% w/v) and HO alone (undiluted, 40%, 20%, 10%, 5% and 2.5% w/v). Microbroth assay followed by subculture was used to determine MBC and MFC. The same protocol was applied after product exposure to catalase. A well-diffusion assay for S. pseudintermedius was used to generate inhibition zones. A TKA for 10 isolates of S. pseudintermedius and 10 isolates of M. pachydermatis was performed. RESULTS: MBC was 20% w/v (5-20% w/v) for HBO and HO. HBO had lower MBC values when compared to HO (P = 0.003). No statistical difference was observed between MSSP/MRSP isolates (HBO P = 0.757, HO P = 0.743). Only HO was affected by catalase (P = 0.015). MFC for HBO was 10% w/v (5-10% w/v) and 40% w/v for HO (20-≥40% w/v). All isolates were killed after 4 h of exposure. CONCLUSIONS AND CLINICAL IMPORTANCE: Staphylococcus pseudintermedius and M. pachydermatis are susceptible to the HBO and these results can be used for future clinical trials.

In vitro antimicrobial activity of narasin against common clinical isolates associated with canine otitis externa.

BACKGROUND: Antimicrobial resistance and antimicrobial stewardship are of ever-increasing importance in veterinary medicine. Re-purposing of old drugs that are not used in human medicine is one approach that addresses the emergence of multidrug resistance in canine skin and ear infections, and can reduce the use of critically important human antibiotic classes. HYPOTHESIS/OBJECTIVES: To determine the antimicrobial activity of narasin, a polyether ionophore conventionally used as a rumen modifier and anticoccidial agent in production animals, against common clinical isolates of canine otitis externa (OE). ANIMALS/ISOLATES: Clinical isolates (n = 110) from canine OE were tested, including 17 meticillin-susceptible Staphylococcus pseudintermedius (MSSP), 13 multidrug-resistant Staphylococcus pseudintermedius (MDRSP), and 20 each of ß-haemolytic Streptococcus spp., Pseudomonas aeruginosa, Proteus mirabilis and Malassezia pachydermatis. METHODS: Bacterial and yeast isolates were subcultured, suspended in broth and inoculated into 96-well plates. Organisms were tested against concentrations of narasin ranging from 0.03 to 128 µg/mL. Minimal inhibitory concentrations (MICs) were determined after overnight incubation. RESULTS: Narasin MICs for staphylococcal and streptococcal isolates ranged from 0.06 to 0.25 µg/mL; MIC50 and MIC90 values for both organisms were 0.125 µg/mL. No MICs were achieved for Pseudomonas or Proteus isolates. There was a weak antifungal effect against M. pachydermatis isolates (MIC 32 to >128 µg/mL). CONCLUSIONS AND CLINICAL RELEVANCE: Narasin was effective against Gram-positive bacteria and had antifungal activity at higher concentrations against M. pachydermatis. However, the lack of Gram-negative activity would prevent its use as a sole antimicrobial agent in cases of canine OE.

Survival of Staphylococcus pseudintermedius in modified Romanowsky staining solutions.

BACKGROUND: Stains that are used regularly for patient-side diagnosis to rapidly identify bacterial and fungal infections could become contaminated by common pathogens, such as Staphylococcus pseudintermedius, during slide immersion. HYPOTHESIS/OBJECTIVES: To determine whether the inoculation of S. pseudintermedius into modified Romanowsky type stains (Quick Dip® ) results in viable bacterial contamination and whether this is influenced by the addition of organic debris (canine hair and skin). METHODS: A clinical isolate of S. pseudintermedius was inoculated into clean and organically contaminated Quick Dip® solutions (methanol fixative, eosin, methylene blue), and positive (broth) and negative (bleach) controls. Each solution was tested for the presence of viable bacteria by counting the number of colony forming units (CFU/mL) at various time points. Solutions also were examined under high power microscopy to count the number of visible bacteria at each time point. RESULTS: Staphylococcus pseudintermedius was able to survive in the clean and contaminated Quick Dip® stains for at least one hour, but by 24 h no viable bacteria remained. Survival of the bacteria was not supported in the fixative at any time point. Staphylococcus pseudintermedius remained visible under high power microscopy for up to 2 weeks in all organically contaminated solutions of the Quick Dip® set. CONCLUSIONS AND CLINICAL IMPORTANCE: Staphylococcus pseudintermedius only remains viable in eosin and methylene blue for short periods of time, but the prolonged visibility of dead organisms could theoretically lead to the misdiagnosis of cytology samples.

Reliability and agreement in the use of four- and six-point ordinal scales for the assessment of erythema in digital images of canine skin.

BACKGROUND: Grading of erythema in clinical practice is a subjective assessment that cannot be confirmed using a definitive test; nevertheless, erythema scores are typically measured in clinical trials assessing the response to treatment interventions. Most commonly, ordinal scales are used for this purpose, but the optimal number of categories in such scales has not been determined. HYPOTHESIS/OBJECTIVES: This study aimed to compare the reliability and agreement of a four-point and a six-point ordinal scale for the assessment of erythema in digital images of canine skin. METHODS: Fifteen digital images showing varying degrees of erythema were assessed by specialist dermatologists and laypeople, using either the four-point or the six-point scale. Reliability between the raters was assessed using intraclass correlation coefficients and Cronbach's α. Agreement was assessed using the variation ratio (the percentage of respondents who chose the mode, the most common answer). Intraobserver variability was assessed by comparing the results of two grading sessions, at least 6 weeks apart. RESULTS: Both scales demonstrated high reliability, with intraclass correlation coefficient values and Cronbach's α above 0.99. However, the four-point scale demonstrated significantly superior agreement, with variation ratios for the four-point scale averaging 74.8%, compared with 56.2% for the six-point scale. Intraobserver consistency for the four-point scale was very high. CONCLUSIONS AND CLINICAL IMPORTANCE: Although both scales demonstrated high reliability, the four-point scale was superior in terms of agreement. For the assessment of erythema in clinical trials, a four-point ordinal scale is recommended.

Survival of Pseudomonas aeruginosa in modified Romanowsky staining solutions.

BACKGROUND: Anecdotal reports suggest that rapid staining solutions can become contaminated with micro-organisms, especially Pseudomonas aeruginosa. HYPOTHESIS/OBJECTIVES: To determine whether inoculation of rapid Romanowsky-type stains with P. aeruginosa results in viable bacterial contamination, which could lead to cross-contamination of slides during cytological staining. METHODS: Pseudomonas aeruginosa was inoculated into clean and organically contaminated staining solutions (fixative, eosin and methylene blue) and positive (broth) and negative (bleach) control solutions. Subsequent viability and survival were detected by measuring colony-forming units per millilitre at various time points up to 2 weeks. Each sample was stained and microscopically examined to determine whether bacteria were visible. RESULTS: No bacteria could be cultured at any time point from the bleach or fixative solution. In clean eosin and methylene blue staining solutions, viable bacteria were recovered for up to 1 h, but by 24 h all bacteria were dead. In staining solutions contaminated with hair and dead skin cells, bacteria survived in methylene blue for up to 1 h, and viable bacteria persisted in the eosin stain for 2 weeks. In solutions containing viable organisms, the bacteria could be observed by microscopic examination; no bacteria were visible when the solutions contained no viable organisms. CONCLUSIONS AND CLINICAL IMPORTANCE: Pseudomonas aeruginosa can survive in commonly used staining solutions for variable periods of time, but is unable to proliferate. Although theoretically this might complicate cytological interpretation and subsequent diagnosis, the likelihood of this in clinical practice appears remote when the correct staining technique is used.

Validation of the Canine Atopic Dermatitis Extent and Severity Index (CADESI)-4, a simplified severity scale for assessing skin lesions of atopic dermatitis in dogs.

BACKGROUND: Severity scales are used to grade skin lesions in clinical trials for treatment of dogs with atopic dermatitis (AD). At this time, only two scales have been validated, namely the Canine Atopic Dermatitis Extent and Severity Index (CADESI)-3 and the Canine Atopic Dermatitis Lesion Index (CADLI). However, the high number of assessed sites makes the CADESI-3 impractical. HYPOTHESIS/OBJECTIVES: The aim of this study was to develop and validate a fourth version of the CADESI that is simpler and quicker to administer. METHODS: Body sites, lesions and severity grades were revised by members of the International Committee on Allergic Diseases of Animals (ICADA). The newly designed CADESI-4 was tested for its validity (i.e. content, construct and criterion), reliability (i.e. inter- and intra-observer reliability and internal consistency), responsiveness (i.e. sensitivity to change) and time to administer. Disease severity benchmarks were chosen using receiver operating characteristic methodology. RESULTS: The CADESI-4 was simplified in comparison to its previous version to comprise 20 body sites typically affected in atopic dogs. Three lesions (erythema, lichenification and alopecia/excoriation) were scored from 0 to 3 at each site. The CADESI-4 had satisfactory validity, reliability and sensitivity to change. On average, the time to administer a CADESI-4 was one-third that of a CADESI-3. Proposed benchmarks for mild, moderate and severe AD skin lesions are 10, 35 and 60, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: The CADESI-4 is simpler to use and quicker to administer than its previous version. The ICADA recommends the CADESI-4 instead of the CADESI-3 to score skin lesions of AD in dogs enrolled in clinical trials.

Putative paraneoplastic pemphigus and myasthenia gravis in a cat with a lymphocytic thymoma.

BACKGROUND: Paraneoplastic pemphigus (PNP) is a rare and severe autoimmune blistering skin disease of humans. It is associated mainly with haematopoietic neoplasia and a unique autoantibody profile. At this time and in animals, PNP has only been reported in dogs. OBJECTIVES: To report clinical, histological and immunological findings in a cat with suspected thymoma-associated PNP. ANIMAL: An 8-year-old female spayed Himalayan cat. RESULTS: The cat presented with a thoracic mass diagnosed as a lymphocytic thymoma. Two weeks postremoval, the cat developed myasthenia gravis, which was controlled with prednisolone and pyridostigmine. The myasthenia gravis resolved, but the cat developed severe cutaneous erosions and ulcers primarily affecting the caudal ventral abdomen and perineum, but also the ventral chest, axillae and medial pinnae. Histopathological analysis revealed changes consistent with pemphigus vulgaris and erythema multiforme, a combination of lesions highly suggestive of PNP. Direct immunofluorescence revealed intercellular epidermal IgG deposition in the lower epidermis, especially in areas of suprabasal clefts. Indirect immunofluorescence revealed antikeratinocyte IgG to basal keratinocytes and bladder epithelial cells. Immunological results supported a diagnosis of PNP. Skin lesions were treated with prednisolone and chlorambucil and, after clinical remission was obtained, the drugs were tapered and eventually discontinued without further recurrence of skin lesions. CONCLUSIONS AND CLINICAL IMPORTANCE: In this cat, clinical, microscopic and immunological findings were consistent with a diagnosis of PNP, with thymoma being the suspected cause.

Evaluation of the short-term echocardiographic effects of two loop diuretics, furosemide and torsemide, in a group of dogs.

BACKGROUND: Two loop diuretics, torsemide and frusemide, can affect the urinary system and consequently the cardiordiovascular haemodynamics in different ways. OBJECTIVES: This study compared a number of echocardiographic parameters and systemic arterial blood pressure (ABP) changes following administration of furosemide or torsemide. METHODS: Five shelter dogs underwent transthoracic two-dimensional M-mode echocardiography to obtain the following measurements: left ventricular internal dimension at end-systole (LVIDs), left ventricular internal dimension at end-diastole (LVIDd), fractional shortening (FS), heart rate (HR) and the distance between the mitral valve socket and the ventricle wall (septal to E Point, SEP). Arterial blood pressure was measured using the oscillometric method. Measurements recorded before treatment (baseline data) were compared to those after the dogs received furosemide (5 mg/kg) or torsemide (0.5 mg/kg). RESULTS: Torsemide significantly reduced blood pressure 1 h after administration, but this was not seen with furosemide. Fractional shortening, LVIDd and SEP decreased following both treatments, but there were no significant differences between the treatment groups. Torsemide increased heart rate above that seen in the furosemide groups. CONCLUSIONS: The results of this study indicate that 1 h after administration, torsemide increases heart rate and decreases blood pressure when compared to furosemide, but both drugs have similar effects on measured cardiovascular indices.

UK-based multicentre cross-sectional study assessing advice requests veterinary dermatologists received from general practitioners.

BACKGROUND: There is little currently little information available regarding the nature of the advice requests veterinary dermatologists receive from general practitioners. Collation of such data could direct continuing veterinary development in the future. METHODS: Dermatologists completed hand-written recording sheets during or after enquiries. Information recorded included the route of enquiry, nature of advice, material provided, practice type and location, animal signalment, presenting signs, diagnosis/differential diagnosis, treatment and referral recommendations, time taken and if charges were made. RESULTS: Twelve dermatology services recorded 768 advice requests over a 6-month period. Most requests were submitted via email and related to canine dermatology (81%). An average of 9.5 minutes was spent replying to requests. Charges were made in 2% of cases. Advice regarding otitis was most commonly sought, followed by pruritus, alopecia and crusting. The most frequently discussed diagnoses included allergy, otitis, pyoderma, demodicosis, dermatophytosis and neoplasia. Antibiotics, anti-pruritics and topical otic medications were the most commonly discussed therapeutics. LIMITATIONS: This is an initial study and therefore there are limitations involving the depth of the data. Additional studies should be completed which identify why advice is sought, decision-making regarding referral, and if advice should be charged similarly to other disciplines. CONCLUSIONS: These findings highlight that veterinarians mostly frequently seek advice on management of common dermatological problems, including allergy, otitis and pyoderma.

Idiopathic generalized sebaceous gland hyperplasia of the Border terrier: a morphometric study.

Skin biopsies from five Border terriers with histologically confirmed idiopathic, generalized sebaceous gland hyperplasia (Group A) were compared morphometrically to those from four unaffected Border terriers (Group B) and the unaffected dogs to biopsies from four other terrier breeds (Group C). Dogs in Group A had significantly higher numbers of sebaceous gland lobules per hair follicle than those in Group B (P=0.020) but there was no significant difference between Groups B and C. The total sebaceous gland lobular area per hair follicle was significantly higher in dogs in Group A than Group B (P=0.020) but there were no differences between Groups B and C. There were no significant differences in the size of the individual sebaceous gland lobules. There were no significant differences in the total number of basal or mature sebocytes between Groups A and B but significantly lower numbers of both cell types were seen in Group C compared to Group B. There were significantly more basal sebaceous cells undergoing mitosis in dogs in Group A than Group B (P=0.017) but no significant difference between Groups B and C. These results indicate that the physical signs of sebaceous gland hyperplasia are caused by an increase in the number of sebaceous gland lobules and total lobular area. Border terriers may be genetically predisposed to the development of idiopathic generalized sebaceous gland hyperplasia compared with other dog breeds but also to sebaceous gland hyperplasia secondary to other dermatopathies.

In vitro Antimicrobial Activity of Robenidine, Ethylenediaminetetraacetic Acid and Polymyxin B Nonapeptide Against Important Human and Veterinary Pathogens.

The emergence and global spread of antimicrobial resistance among bacterial pathogens demand alternative strategies to treat life-threatening infections. Combination drugs and repurposing of old compounds with known safety profiles that are not currently used in human medicine can address the problem of multidrug-resistant infections and promote antimicrobial stewardship in veterinary medicine. In this study, the antimicrobial activity of robenidine alone or in combination with ethylenediaminetetraacetic acid (EDTA) or polymyxin B nonapeptide (PMBN) against Gram-negative bacterial pathogens, including those associated with canine otitis externa and human skin and soft tissue infection, was evaluated in vitro using microdilution susceptibility testing and the checkerboard method. Fractional inhibitory concentration indices (FICIs) and dose reduction indices (DRI) of the combinations against tested isolates were determined. Robenidine alone was bactericidal against Acinetobacter baumannii [minimum inhibitory concentrations (MIC) mode = 8 µg/ml] and Acinetobacter calcoaceticus (MIC mode = 2 µg/ml). Against Acinetobacter spp., an additivity/indifference of the combination of robenidine/EDTA (0.53 > FICIs > 1.06) and a synergistic effect of the combination of robenidine/PMBN (0.5 < FICI) were obtained. DRIs of robenidine were significantly increased in the presence of both EDTA and PMBN from 2- to 2048-fold. Robenidine exhibited antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, in the presence of sub-inhibitory concentrations of either EDTA or PMBN. Robenidine also demonstrated potent antibacterial activity against multidrug-resistant Gram-positive pathogens and all Gram-negative pathogens isolated from cases of canine otitis externa in the presence of EDTA. Robenidine did not demonstrate antibiofilm activity against Gram-positive and Gram-negative bacteria. EDTA facilitated biofilm biomass degradation for both Gram-positives and Gram-negatives. The addition of robenidine to EDTA was not associated with any change in the effect on biofilm biomass degradation. The combination of robenidine with EDTA or PMBN has potential for further exploration and pharmaceutical development, such as incorporation into topical and otic formulations for animal and human use.

Treatment of Selected Canine Dermatological Conditions in Portugal - A Research Survey.

INTRODUCTION: Staphylococcus pseudintermedius and Malassezia pachydermatis often cause skin diseases in dogs. MATERIAL AND METHODS: An online survey was e-mailed to veterinary practices nationwide covering demographics, diagnosis methods, and oral and topical treatment options. Of the 740 surveys sent, 100 complete replies were obtained. RESULTS: The majority of clinicians were unaware of the existence of the International Society for Companion Animal Infectious Diseases guidelines or did not follow them (53%). Oral antibiotics were used universally for superficial bacterial folliculitis treatment, particularly amoxicillin-clavulanic acid (100%), cephalexin (94%), enrofloxacin (67%), or marbofloxacin (60%). For fold dermatitis (FD) and otitis externa (OE), oral antibiotics were also given as treatment in 88% and 82% of cases, respectively. Oral antifungals were often prescribed for generalised Malassezia dermatitis (85%), FD (70%), and OE (59%). S. pseudintermedius and M. pachydermatis were frequently treated topically, particularly with antibacterials or antifungals only, or a combination of antibacterials, antifungals, and glucocorticoids. Alternative options such as honey-based products were not frequently used. CONCLUSION: Our survey suggests that oral antibiotics are overused by Portuguese clinicians despite the spread of antibiotic resistant S. pseudintermedius. Oral antibiotics and antifungals are commonly prescribed for skin conditions manageable with topical treatments.

In vitro antimicrobial activity of monensin against common clinical isolates associated with canine otitis externa.

Antimicrobial resistance and antimicrobial stewardship are of ever-increasing importance in veterinary medicine. Multidrug-resistant infections of the canine skin and ear continue to emerge, but the use of antibiotic classes of critical importance to human medicine may not represent good antimicrobial stewardship. Repurposing of old drugs that are not used in human medicine is one approach that addresses both these issues. In this study, the minimal inhibitory concentration (MIC) of monensin for 111 bacterial and yeast canine otitis isolates was determined using microdilution methodology according to Clinical Laboratory Standards Institute (CLSI) guidelines. Monensin was effective against all Gram-positive bacteria including the multidrug-resistant staphylococcal strains with MICs ranging from 1 to 4 µg/ml, but lacked antimicrobial activity against Gram-negative bacteria and yeast isolates. Monensin has potential to be incorporated as one of the main components in an otic formulation.

Bioluminescent murine models of bacterial sepsis and scald wound infections for antimicrobial efficacy testing.

There are very few articles in the literature describing continuous models of bacterial infections that mimic disease pathogenesis in humans and animals without using separate cohorts of animals at each stage of disease. In this work, we developed bioluminescent mouse models of partial-thickness scald wound infection and sepsis that mimic disease pathogenesis in humans and animals using a recombinant luciferase-expressing Staphylococcus aureus strain (Xen29). Two days post-scald wound infection, mice were treated twice daily with a 2% topical mupirocin ointment for 7 days. For sepsis experiments, mice were treated intraperitoneally with 6 mg/kg daptomycin 2 h and 6 h post-infection and time to moribund monitored for 72 h. Consistent bacterial burden data were obtained from individual mice by regular photon intensity quantification on a Xenogen IVIS Lumina XRMS Series III biophotonic imaging system, with concomitant significant reduction in photon intensities in drug-treated mice. Post-mortem histopathological examination of wounds and bacterial counts in blood correlated closely with disease severity and total flux obtained from Xen29. The bioluminescent murine models provide a refinement to existing techniques of multiple bacterial enumeration during disease pathogenesis and promote animal usage reduction. The models also provide an efficient and information-rich platform for preclinical efficacy evaluation of new drug classes for treating acute and chronic human and animal bacterial infections.