R. Bond

Superficial veterinary mycoses

Dermatophytes are significant pathogens in animal health due to their zoonotic potential, the economic consequences of infection in farm animal and fur production systems, and the distressing lesions they cause in small domestic pets. Malassezia spp are normal commensal and occasional pathogens of the skin of many veterinary species. Malassezia pachydermatis is a very common cause of otitis and pruritic dermatitis in dogs but is of less importance in other veterinary species. Dermatophytosis, and Malassezia otitis and dermatitis, represent the superficial mycoses of greatest significance in companion and farm animal health. Although the dermatophytes and Malassezia spp both exist in the stratum corneum of mammalian skin, there are important differences in the epidemiology, pathogenesis, and clinical consequences of infection. Dermatophytes are significant due to their zoonotic potential, the economic consequences of infection in farm animal and fur production systems, and the concern for owners of pets with inflammatory skin disease that is sometimes severe. Malassezia spp are normal commensals and occasional pathogens of the skin for many veterinary species, and M pachydermatis is a very common cause of otitis and pruritic dermatitis in dogs. This chapter will focus on the epidemiologic, clinical, diagnostic, and therapeutic aspects of dermatophytosis and Malassezia dermatitis in veterinary species. There are generally only sporadic reports of other superficial mycoses, such as candidiasis, piedra, and Rhodotorula dermatitis in veterinary medicine, and these are not included here.

Isolation of Malassezia sympodialis and Malassezia globosa from healthy pet cats

Lipomatous infiltration of the canine salivary gland LESIONS in the salivary glands of dogs are rare according to one review only approximately 0-3 per cent of pathological diagnoses. This paper describes seven cases in which either a submandibular or a parotid gland was enlarged by the infiltration of fat. In each case the parenchymal tissue had been replaced extensively by irregular lobules of uniform, well differentiated fat cells; there was only a slight degree of acinar atrophy and no signs of inflammation or fibrosis. The lipomas had been removed surgically and in three cases they did not recur and the dogs survived for up to six years. The cause of the fatty infiltration is unknown, but the causes of similar lesions in human beings are discussed. BROWN, P. J., LUCKE, V. M., SOZMEN, M., WHITBREAD, T. J. & WYATT, J. M. (1997) Journal of Small Animal Practice 38, 234 Plasma cortisol following calf dehoming USING plasma cortisol as an index of distress in a New Zealand study on Friesian heifer calves aged 14 to 16 weeks, dehoming was carried out without local analgesia using either a shallow or a deep scoop; the gauging procedure took less than 15 seconds. Jugular venepuncture was performed 25 minutes before, 25 minutes afterwards and 15 further times up to nine hours after dehoming. Both methods caused a prolonged increase of plasma cortisol, which returned to normal levels with eight and six hours following shallow scoop and deep scoop, respectively. Linear regression analysis showed no significant correlation between wound depth and integrated cortisol response. McMEEKAN, C. M., MELLOR, D. J., STAFFORD, K. J., BRUCE, R. A., WARD, R. N. & GREGORY, N. G. (1997) New Zealand Veterinary Journal 45, 72

Survey of flea infestation in dogs and cats in the United Kingdom during 2005

During 2005, 31 uk veterinary practices participated in a survey of flea infestation, during which 2653 dogs and 1508 cats were examined for evidence of flea infestation and skin disease compatible with flea allergy dermatitis (fad). The prevalence of flea infestation in the cats was 21·09 per cent, significantly (P<0·001) higher than in the dogs (6·82 per cent). The prevalence of skin lesions compatible with fad in the cats (8·02 per cent) was also significantly (P<0·001) higher than in the dogs (3·32 per cent). Flea infestations were more common in households with cats and with more than one pet. Of 467 fleas identified from the cats, 462 (98·93 per cent) were Ctenocephalides felis, one was Ctenocephalides canis, one was Archaeopsylla erinacei, two were Pulex irritans, and one was Spilopsyllus cuniculi. Of 336 fleas identified from the dogs, 313 (93·15 per cent) were C felis, five were C Canis, 12 were A erinacei, five were P irritans, and one was Ceratophyllus (Nosophyllus) fasciatus. Almost half of the owners of the dogs and cats were unaware of their pets flea infestation. The overall prevalence of fleas and/or skin lesions that could potentially be compatible with fad was 7·46 per cent in the dogs and 22·28 per cent in the cats.

Isolation of Malassezia sympodialis from feline skin

Carriage of Malassezia yeasts was investigated in 17 cats in two colonies using a lipid-supplemented culture medium. Malassezia pachydermatis was isolated from one cat. Lipid-dependent Malassezia yeasts with electrophoretic karyotypes consistent with M. sympodialis were isolated from all six cats in one group and from one of 11 in the second group. To our knowledge, this is the first report of the isolation of lipid-dependent yeasts from cats.

A review of topical therapy for skin infections with bacteria and yeast.

BACKGROUND Cutaneous infections with bacteria and yeasts are common in small animal practice. Treatment with systemic antibiotics or antifungal agents may not be ideal, because of the increasing development of multiresistant organisms, the cost and the possible adverse effects. Topical antimicrobials may be used as adjunctive therapy to systemic treatment or as sole therapy instead of systemic treatment. OBJECTIVE This literature review evaluated studies on topical antimicrobial treatment of skin infections. METHODS In vitro and in vivo studies evaluating topical antimicrobial agents were identified using a number of electronic and manual searches of textbooks and articles. Studies were evaluated, and the evidence for or against the use of the topical agents was extracted. RESULTS There is good evidence for the efficacy of chlorhexidine and, to a lesser degree, benzoyl peroxide in canine bacterial skin infections. There is limited evidence for the efficacy of silver sulfadiazine and medical honey against bacterial skin infections in the dog, and for the efficacy of hydrogen peroxide and stannous fluoride in the horse. Good evidence supports the use of a combination of chlorhexidine and miconazole in dogs with cutaneous Malassezia infections. There is insufficient evidence to recommend any other topical therapy for use in cutaneous infections. CONCLUSIONS AND CLINICAL IMPORTANCE Although many antimicrobial topicals are marketed in veterinary dermatology, the efficacy has been reported for only a minority of agents. Randomized controlled trials evaluating various topical treatments are therefore urgently needed.

Case-control risk factor study of methicillin-resistant Staphylococcus pseudintermedius (MRSP) infection in dogs and cats in Germany

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as a highly drug-resistant small animal veterinary pathogen. Although often isolated from outpatients in veterinary clinics, there is concern that MRSP follows a veterinary-hospital-associated epidemiology. This studys objective was to identify risk factors for MRSP infections in dogs and cats in Germany. Clinical isolates of MRSP cases (n=150) and methicillin-susceptible S. pseudintermedius (MSSP) controls (n=133) and their corresponding host signalment and medical data covering the six months prior to staphylococcal isolation were analysed by multivariable logistic regression. The identity of all MRSP isolates was confirmed through demonstration of S. intermedius-group specific nuc and mecA. In the final model, cats (compared to dogs, OR 18.5, 95% CI 1.8-188.0, P=0.01), animals that had been hospitalised (OR 104.4, 95% CI 21.3-511.6, P<0.001), or visited veterinary clinics more frequently (>10 visits OR 7.3, 95% CI 1.0-52.6, P=0.049) and those that had received topical ear medication (OR 5.1, 95% CI 1.8-14.9, P=0.003) or glucocorticoids (OR 22.5, 95% CI 7.0-72.6, P<0.001) were at higher risk of MRSP infection, whereas S. pseudintermedius isolates from ears were more likely to belong to the MSSP-group (OR 0.09, 95% CI 0.03-0.34, P<0.001). These results indicate an association of MRSP infection with veterinary clinic/hospital settings and possibly with chronic skin disease. There was an unexpected lack of association between MRSP and antimicrobial therapy; this requires further investigation but may indicate that MRSP is well adapted to canine skin with little need for selective pressure.

Comparison of a chlorhexidine and a benzoyl peroxide shampoo as sole treatment in canine superficial pyoderma

The clinical and antibacterial efficacy of two shampoos used as a sole antibacterial treatment in dogs with superficial pyoderma were investigated and compared. In a randomised, partially blinded study, a 3 per cent chlorhexidine gluconate shampoo (Chlorhex 3; Leo Animal Health) was compared against a 2.5 per cent benzoyl peroxide shampoo (Paxcutol; Virbac) in 22 dogs with superficial pyoderma. Dogs were washed two to three times weekly with a 10-minute contact time over 21 days. Clinical scores and bacterial counts were assessed on days 1, 8 and 22 and compared within and between treatment groups; overall response was assessed at the end of the study. Twenty dogs completed the study; 15 (68.2 per cent) showed an overall clinical improvement and the clinical signs resolved in three chlorhexidine-treated dogs. In the chlorhexidine-treated group, scores for papules/pustules (P<0.001), investigator-assessed pruritus (P=0.003), total bacterial counts (P=0.003) and counts for coagulase-positive staphylococci (P=0.003) were reduced after three weeks. Scores and bacterial counts did not vary significantly in the benzoyl peroxide-treated group.

Evaluation of a detergent scrub technique for the quantitative culture of Malassezia pachydermatis from canine skin

A detergent scrub technique using wash fluid consisting of 0.075 M phosphate-buffered saline, pH 7.9 containing 0.1 per cent Triton X-100 was evaluated for the quantitative culture of Malassezia pachydermatis from canine skin. Preliminary studies showed that the detergents Triton X-100, Tween 40 and Tween 80 were equally able to disperse suspensions of pure cultures of M pachydermatis, but that the yeast counts were significantly reduced (P < 0.001) after suspension in saline, Triton X-100 or Tween 40 for two hours. The counts in skin washings were also reduced (P < 0.001) after suspension for three hours in 0.1 and 0.05 per cent solutions of Triton X-100. Vortexing, or manual or mechanical shaking of the samples yielded comparable counts. The correlation between the counts on diseased skin measured by using detergent scrubs and a contact plate technique was highly significant (P < 0.001). The detergent scrub technique was suitable for the quantitation of M pachydermatis on canine skin provided that the samples were processed without delay.

Increasing antimicrobial resistance in clinical isolates of Staphylococcus intermedius group bacteria and emergence of MRSP in the UK

Frequencies of antimicrobial resistance were determined amongst 14,555 clinical Staphylococcus intermedius group (SIG) isolates from UK dogs and cats to estimate resistance trends and quantify the occurrence of meticillin-resistant Staphylococcus pseudintermedius (MRSP). Reports from two diagnostic laboratories (13,313 general submissions, 1242 referral centre only submissions) were analysed retrospectively (2003/2006–2012). MRSP were defined by phenotypic resistance to meticillin and concurrent broad β-lactam resistance; a subset was confirmed genetically (SIG-specific nuc and mecA). Trends were analysed by Cochran-Armitage test. Resistance remained below 10 per cent for cefalexin, amoxicillin-clavulanic acid and the fluoroquinolones. Increasing resistance trends were seen in both laboratories for ampicillin/amoxicillin (both P<0.001), cefovecin (both P<0.046) and enrofloxacin (both P<0.02). Resistance to cefalexin increased over time in referral hospital isolates (P<0.001) to clindamycin (P=0.01) and trimethoprim-sulfamethoxazole (P=0.001) amongst general laboratory submissions. Overall, 106 MRSP were isolated (0.7 per cent of submissions) including 32 (2.6 per cent of submissions, all genetically confirmed) from the referral centre population (inter-laboratory difference P<0.001). Against a background of widely susceptible SIG isolates, a new trend of increasing resistance to important antimicrobials was identified overtime and the emergence of MRSP from UK clinical cases was confirmed. Attention to responsible use of antibacterial therapy in small animal practice is urgently needed.

Intradermal test reactivity to Malassezia pachydermatis in atopic dogs

THE commensal yeast Malassezia pachydermatis is now recognised as a common cause of otitis and dermatitis in dogs (Gustafson 1955, Dufait 1983, Larsson and others 1988, Mason and Evans 1991). The factors which favour proliferation of the yeast are poorly understood. Concurrent skin diseases are often recognised and, among these, atopic disease is frequently seen in dogs with Malassezia dermatitis (Mason and Evans 1991, Bond and others 1996). Groups of atopic dogs have been shown to have elevated skin populations of the yeast when compared with groups of healthy dogs (Bond and others 1994, White and others 1998), although Mpachydermatis populations in the skin of individual atopic dogs can be either elevated or within normal limits. In the USA, immediate intradermal test reactivity has been observed in atopic dogs following the injection of Mpachydermatis extracts at concentrations which cause no reaction in healthy dogs, suggesting that type I hypersensitivity responses to yeast allergens could contribute to the clinical signs in some cases of canine atopic disease (Morris and oth-