Skin infections such as surface and superficial bacterial pyodermas

bs_bs_banner Carriage rate and antibiotic susceptibility of coagulase-positive staphylococci isolated from healthy dogs in Victoria, Australia DC Bean* and SM Wigmore Background Studies in Australia and elsewhere have shown high levels of antibiotic resistance in coagulase-positive staphylococci in dogs visiting veterinary clinics with pyoderma and related conditions. Although important, such studies tend to overestimate the burden of resistance. The aim of the current study was to investigate the prevalence of coagulase-positive staphylococci in healthy dogs in Central Victoria to assess the level of antibiotic resistance among these isolates. Methods We recruited 117 healthy dogs into the study. Swabs were taken at four sites (ear, mouth, nose, perineum) and staphylococcal species identified and isolated using culture and biochemical techniques. Results Staphylococcus pseudintermedius and S. aureus were recovered from 100 and 17 dogs, respectively; 15 dogs were simultaneously co-colonised with both organisms. The mouth and perineum were the most sensitive sites for recovery of these organisms. The most commonly encountered resistances were penicillin (95.2% and 72.4% in S. aureus and S. pseudintermedius, respectively) and doxycycline/tetracycline (19.7% in S. pseudintermedius). No methicillin-resistant S. aureus were recovered, but two phenotypically methicillin-resistant S. pseudintermedius (MRSP) isolates were recovered, although only one was PCR-positive for the meca gene. Notably the MRSP isolate was multidrug resistant, as it also exhibited resistance to mupirocin and erythromycin. Conclusion With the exception of penicillin, doxycycline and tetracycline, the level of resistance to the antimicrobial agents tested was minimal. Prudent antibiotic use in treating companion animals with skin infections will reduce the selection of MRSP and other multidrug-resistant bacteria. Keywords antimicrobial resistance; dogs; pyoderma Abbreviations MRSP, methicillin-resistant S. pseudintermedius; VP, Voges-Proskauer test for acetoin production Aust Vet J 2016;94:456 460 doi: 10.1111/avj.12528 Skin infections such as surface and superficial bacterial pyodermas are among the most common reasons why dog owners seek veterinary attention. 1 Staphylococcal species are most frequently involved in the skin infections of dogs, with the most clinically relevant species being Staphylococcus pseudintermedius and S. aureus. Staphylococcus pseudintermedius is part of the dog s normal bacterial flora, but in some instances, often when concurrent *Corresponding author. Federation University Australia, Faculty of Science & Technology, PO Box 663, Ballarat, Victoria 3353, Australia; d.bean@federation.edu.au allergic or traumatic skin diseases occur, secondary skin infection may result. There has been a worldwide increase in the prevalence of resistance to commonly used antimicrobial agents. 2 Methicillin resistance is of particular importance as it is conferred by presence of the meca gene, which renders the organism resistant to β-lactam antibiotics (e.g. penicillins and cephalosporins) which are commonly used in oral treatment of canine pyoderma. 3 Methicillin-resistant staphylococci may also acquire resistance to other non-β-lactam antibiotics, further complicating treatment options. Although methicillin-resistant S. pseudintermedius (MRSP) has been documented from cases of canine pyoderma in Australia, 4,5 there is a paucity of data regarding the prevalence of this bacterium among healthy Australian dogs. The current project sought to determine the carriage rate and distribution of both S. aureus and S. pseudintermedius from healthy dogs in Victoria. Furthermore, antimicrobial susceptibility to a number of different classes of drug, including methicillin, was investigated. Materials and methods Dog recruitment and sample collection Healthy animals were recruited from a dog obedience school in Ballarat, Victoria, over a period of 4 weeks from mid-march to mid-april, 2015. Dog owners travelled extensively from around Central Victoria to attend the school, so the catchment area for this study was considerably wider than the city of Ballarat alone. Owners were asked to give written consent prior to the taking of samples from the dogs. Once consent was given each dog was swabbed in four locations: ear, mouth, nose and perineum. Samples were taken using a sterile cotton-tipped swab and then placed in Amies transport medium with charcoal. All specimens were processed within 6 h of collection. The protocol was approved by the Federation University Animal Ethics Committee (application no. 15-001). Isolation and characterisation of staphylococci After sample collection, the cotton tip of each swab was aseptically broken off and enriched in 10 ml of tryptone soya broth (Oxoid, Basingstoke, UK) supplemented with 8% NaCl. Broths were incubated at 37 C for 24 h before subculturing on to Baird-Parker agar (Becton, Dickinson & Co., Sparks, MD, USA). Plates were incubated at 37 C for 48 h before isolates showing growth characteristic of Staphylococcus were subcultured onto tryptone soya agar (Oxoid) and incubated at 37 C for 24 h. Each isolate was confirmed as a Staphylococcus species by Gram stain, catalase and oxidase tests. 456

Speciation of staphylococci Each staphylococcal isolate recovered was tested for coagulase activity using the tube method. All coagulase-positive staphylococci were further speciated on the basis of two biochemical tests: acetoin production (Voges-Proskauer: VP) and polymyxin B susceptibility. 6 Isolates were considered to be S. aureus if they were VP positive and polymyxin B resistant (zone 10 mm); isolates that were VP negative and polymyxin B susceptible (zone 11 mm) were considered to be S. pseudintermedius. Positive control strains included S. aureus ATCC 25923 and S. pseudintermedius ATCC 49444. In instances where a species could not be designated according to these two phenotypic results, identification was made using a molecular assay previously described. 7 All isolates were archived in long-term storage as glycerol stocks and stored at 80 C. mupirocin resistance using 5-μg disc diffusion methods. 12 It is no longer recommended to use disc diffusion to screen for nonsusceptibility to vancomycin; however, for the purpose of this study the historic cut-off of 14 mm was used. 13 PCR detection of the meca gene Lysates were prepared by suspending isolated colonies in sterile distilled water and boiling for 10 min. Cell debris was removed by centrifugation and the supernatant was used as template. PCR was performed using MyTaq TM Red Mix (Bioline, Eveleigh, NSW, Aust). The meca gene was detected using the following primers: meca1 AAA ATC GAT GGT AAA GGT TGG C and meca2 AGT TCT GCA GTA CCG GAT TTG C as described by Murakami et al. 14 Antimicrobial susceptibility testing Susceptibility to 19 antibiotics was determined by disc diffusion assays. CLSI disc diffusion methods were used for all susceptibility testing. Results for different antimicrobials were interpreted with different standards: amoxicillin clavulanic acid, cephalexin (interpreted as cephalothin), chloramphenicol, clindamycin, enrofloxacin, erythromycin, gentamicin, penicillin, rifampicin and tetracycline were interpreted according to CLSI VET01-S2. 8 The antimicrobials ciprofloxacin, linezolid, quinupristin dalfopristin and trimethoprim were interpreted according to CLSI M100-S22. 9 For S. aureus isolates, cefoxitin was interpreted according to CLSI VET01-S2 and cefoxitin zones for S. pseudintermedius isolates were interpreted according to Bemis et al. 10 Oxacillin susceptibility was determined according to CLSI M100-S22 for S. aureus isolates and CLSI VET01-S2 for S. pseudintermedius isolates. Doxycycline susceptibility was interpreted according to CLSI M100-S22 for S. aureus and according to Maaland et al. for S. pseudintermedius. 11 Isolates were also tested for Table 1. Numbers of dogs harbouring coagulase-positive staphylococci recovered from four sampling sites of 117 healthy dogs in Central Victoria, Australia Isolation site S. aureus S. pseudintermedius EA 1 (5.9%) 4 (4.0%) MO 6 (35.3%) 6 (6.0%) NA 4 (23.5%) 2 (2.0%) PM 3 (17.6%) 12 (12.0%) EA/MO 0 (0%) 3 (3.0%) EA/NA 0 (0%) 1 (1.0%) EA/PM 0 (0%) 1 (1.0%) MO/NA 2 (11.8%) 6 (6.0%) MO/PM 0 (0%) 18 (18.0%) NA/PM 0 (0%) 10 (10.0%) EA/MO/NA 0 (0%) 6 (6.0%) EA/MO/PM 0 (0%) 4 (4.0%) MO/NA/PM 1 (5.9%) 13 (13.0%) EA/MO/NA/PM 0 (0%) 14 (14.0%) Total 17 100 EA, ear; MO, mouth; NA, nose; PM, perineum. Statistical analysis Tests of significance were performed by chi-square analysis using Yates correction as appropriate. Results Prevalence of coagulase-positive staphylococci in dogs A total of 117 dogs were recruited into this study: 50 (42.7%) males, 65 (55.6%) females and 2 of unknown sex (1.7%); 34 (29.1%) of the dogs were puppies (<12 months), 79 (67.5%) were adults ( 12 months) and the age of 4 dogs (3.4%) was unknown. Coagulase-positive staphylococci were isolated from 102 (87.2%) of the dogs: a total of 249 isolates were recovered. Coagulase-positive staphylococci could be differentiated as S. pseudintermedius or S. aureus on the basis of polymyxin susceptibility and a negative VP test in all but one isolate. The remaining isolate (VP positive) was confirmed as S. pseudintermedius by molecular assay. 7 Of the 117 dogs, 85 (72.6%) only harboured S. pseudintermedius, 2(1.7%) only had S. aureus and 15 (12.8%) were co-colonised with S. pseudintermedius and S. aureus. Staphylococcus pseudintermedius was most frequently recovered from the perineum, with 72 (61.5%) dogs yielding a positive result. This site was followed by the mouth (60.7%), nose (44.4%) and ear (28.2%). Staphylococcus aureus, by contrast, was most frequently recovered from the mouth (7.7%), followed by the nose (6.0%), perineum (3.4%) and ear (0.9%). When it was recovered, S. aureus was generally only isolated from one site on the dog (in 82% of cases), whereas S. pseudintermedius typically colonised multiple sites on the host, with only 24% of the dogs harbouring the organism at a single site; 14% of the dogs harbouring S. pseudintermedius did so in all four of the sites investigated (Table 1). The distribution of coagulase-positive staphylococci on their hosts is shown in Table 2. Recovery of S. aureus was significantly higher from female dogs (P < 0.05). Recovery of S. pseudintermedius was largely independent of sex, although colonisation rates were generally higher in unneutered animals. Staphylococcus aureus was more frequently recovered from puppies than from adult dogs (P < 0.05), but the age of the dog did not significantly affect S. pseudintermedius colonisation. 457

Table 2. Distribution of Staphylococcus aureus (n = 21) and S. pseudintermedius (n = 228) by sampling site, sex and age as a proportion of the total number of specimens from healthy dogs in Central Victoria, Australia No. of dogs No. specimens No. of recovered isolates (% of specimens) S. aureus S. pseudintermedius Site Ear 117 117 1 (0.8%) 33 (28.2%) Nose 117 117 7 (6.0%) 52 (44.4%) Mouth 117 117 9 (7.7%) 71 (60.7%) Perinium 117 117 4 (3.4%) 72 (61.5%) Sex M 15 60 0 (0%) 33 (55%) MN 35 140 3 (2.1%) 65 (46.4%) F 19 76 10 (13.2%) 41 (53.9%) FN 46 184 7 (3.8%) 85 (46.2%) Unknown 3 12 1 (8.3%) 4 (33.3%) Age <12 months 34 136 12 (8.8%) 63 (46.3%) 12 months 79 316 7 (2.2%) 155 (49.1%) Unknown 4 16 2 (12.5%) 10 (62.5%) FN, female neutered; MN, male neutered. Antibiotic susceptibilities of coagulase-positive staphylococci from dogs The prevalence of resistance to the 19 antimicrobial agents tested is shown in Table 3. Four owners reported their dogs had received antibiotics in the preceding 12 months, although details of the drugs used were not available. Although resistance to a number of different antibiotics was observed, the prevalence of resistance generally remained low, with the exception of penicillin resistance. Penicillin resistance was observed in 73.5% of isolates, but was significantly higher (P < 0.05) among S. aureus isolates (95.2%) than among S. pseudintermedius (72.4%). Conversely, doxycycline and tetracycline resistance was significantly (P < 0.05) more prevalent in S. pseudintermedius (18.4%) than in S. aureus (0%). Isolates showing phenotypic resistance to cefoxitin were confirmed as methicillin-resistant by meca PCR. Two S. pseudintermedius isolates were recovered that were phenotypically resistant to cefoxitin (and also had zones 17 mm in the 1-μg oxacillin disc test); however, the meca gene was only detected in one of these. Therefore, only one isolate of MRSP was confirmed in the current study. The MRSP isolate was multidrug resistant, as it also exhibited resistance to erythromycin and mupirocin. Unexpectedly, all isolates (including the MRSP isolate) were susceptible to amoxicillin clavulanic acid in vitro. Discussion The carriage rate of S. aureus and S. pseudintermedius in the current study was 14.5% and 85.5%, respectively, which is consistent with colonisation rates of healthy dogs in other studies; carriage of S. aureus has been reported as 6% 15 and 8.8%, 16 while S. pseudintermedius was recovered significantly more frequently at 55%, 17 68% 15 and 87.4%. 18 Dual carriage of S. aureus and S. pseudintermedius was common, being identified in 15 dogs (12.8%), which sits among other reports of 2% in healthy dogs 15 and 22% of mammalian pets. 19 Our study identified the perineum, followed closely by the mouth, as the most sensitive sites for screening animals for the presence of S. pseudintermedius. This is consistent with another study showing the most frequent carriage sites were also the perineum (66%) and the mouth (65%). 20 A review determined the S. pseudintermedius carriage rate to be 57% (range, 42 74%) for the mouth and 52% (range, 28 72%) for the perineum. 6 Therefore, either site is a good candidate for recovery of S. pseudintermedius. The combination of mouth and perineum has been shown to be 100% sensitive for the detection of S. pseudintermedius. 19 In our study this combination was 93% sensitive for the detection of S. pseudintermedius and 71% sensitive for S. aureus. Our finding that colonisation with S. aureus was higher in female dogs agrees with previously published data. 16 It has been speculated that behavioural differences or hormonal factors may influence colonisation. Indeed, more than half (58.8%) of female dogs colonised with S. aureus were entire females, supporting the suggestion that hormonal differences may play a role. The higher recovery rate of S. aureus from puppies may be the result of transmission from humans via increased interaction and handling of puppies. Alternatively, given that S. aureus was carried at a higher rate in the mouth of entire females, the interaction of puppies with their mothers, particularly in being groomed and moved around, may be reflected by the higher levels of S. aureus. The recovery of methicillin-resistant isolates in the current study was low (0.4%). Although MRSP has been previously documented in cases of canine pyoderma in Australia, 4 less is known about the 458

Table 3. Antimicrobial resistance in coagulase-positive staphylococci (n = 249) isolated from four sites on 117 healthy dogs in Central Victoria, Australia Antimicrobial S. aureus (n = 21) S. pseudintermedius (n = 228) β-lactams Amoxicillin-Clavulanic acid 0 (0.0%) 0 (0.0%) Cefoxitin 0 (0.0%) 2 (0.9%) Cephalexin 0 (0.0%) 1 (0.4%) Oxacillin 0 (0.0%) 2 (0.9%) Penicillin 20 (95.2%) 165 (72.4%) Tetracyclines Doxycycline 0 (0.0%) 45 (19.7%) Tetracycline 0 (0.0%) 45 (19.7%) Fluoroquinolones Ciprofloxacin 0 (0.0%) 0 (0.0%) Enrofloxacin 0 (0.0%) 0 (0.0%) Other antimicrobials Chloramphenicol 0 (0.0%) 4 (1.8%) Clindamycin 0 (0.0%) 1 (0.4%) Erythromycin 0 (0.0%) 2 (0.9%) Gentamicin 0 (0.0%) 1 (0.4%) Linezolid 0 (0.0%) 0 (0.0%) Mupirocin 0 (0.0%) 1 (0.4%) Quinupristin-Dalfopristin 0 (0.0%) 0 (0.0%) Rifampin 0 (0.0%) 0 (0.0%) Trimethoprim 0 (0.0%) 2 (0.9%)* Vancomycin 0 (0.0%) 0 (0.0%) * Includes one isolate of intermediate resistance. prevalence among healthy dogs in the community. A prospective study of 27 dogs presenting with superficial bacterial pyoderma at two Sydney teaching hospitals identified one dog as carrying MRSP. 5 Global studies of MRSP carriage among healthy dogs have also shown the prevalence to be low, with a Canadian study from 2011 finding no MRSP in 173 healthy dogs, 18 a recent Tunisian study reporting no MRSP from 100 healthy dogs 17 and a US study recovering only two isolates from 123 healthy dogs. 21 Mupirocin resistance remains rare in S. pseudintermedius, with 1 of 581 isolates exhibiting resistance in a US study. 22 In the current study we identified one isolate displaying mupirocin resistance using the 5-μg disc diffusion method described by Fuchs et al. 12 A limitation of this method is that it does not distinguish between low- and high-level mupirocin resistance and has been further refined by a two-disc method. 23 Nevertheless, the discovery of a MRSP strain also exhibiting mupirocin resistance does suggest that, although currently rare, multidrug-resistant isolates are emerging. Prospective community studies of commensal bacterial flora are required for ongoing surveillance of emerging resistance. The current study also identified a significant proportion of doxycycline- and tetracycline-resistant S. pseudintermedius (19.7%), although no such resistances were observed for the S. aureus isolates. A Canadian study similarly found a higher rate of tetracycline resistance among canine S. pseudintermedius (34%) compared with veterinary S. aureus isolates (14% from assorted animals). 24 This elevated rate of resistance to tetracyclines may be related to the prescribing habits of Australian veterinarians. An Australian study from 2001 investigating antibacterial agents used in dogs found doxycycline to be the most frequently prescribed non-β-lactam drug. 25 Although the use of tetracyclines to treat pyoderma is not recommended in dogs, the use of doxycycline in treating other infections is common and may be driving the emerging resistance in S. pseudintermedius. Moreover, with the emergence of MRSP, clinicians are being forced to consider drugs not traditionally used on skin. Doxycycline s lipophilic nature makes it a suitable alternative to β-lactams for treating MRSP infections when susceptibility data support it. As has been documented by others, there are no standardised methods for the recovery of S. pseudintermedius from clinical specimens and this complicates comparison of data between studies. 19 This is no doubt at least partially responsible for the differences observed in S. pseudintermedius carriage rates. Our study found that Baird- Parker agar (with lecithinase production) was an effective medium for identification and recovery of S. pseudintermedius. Taken together, our data demonstrate that, with the exception of penicillin, doxycycline and tetracycline resistance in S. pseudintermedius remains uncommon in healthy dogs in rural Victoria. Prudent antibiotic use in treating companion animals with skin infections will reduce the selection of MRSP and other multidrug-resistant bacteria important to both animal and human health. Acknowledgment The assistance of Norm Baker and the Ballarat dog obedience school is gratefully acknowledged. References 1. Lund EM, Armstrong PJ, Kirk CA et al. Health status and population characteristics of dogs and cats examined at private veterinary practices in the United States. J Am Vet Med Assoc 1999;214:1336 1341. 2. Moodley A, Damborg P, Nielsen SS. Antimicrobial resistance in methicillin susceptible and methicillin resistant Staphylococcus pseudintermedius of canine origin: literature review from 1980 to 2013. Vet Microbiol 2014;171:337 341. 3. van Duijkeren E, Catry B, Greko C et al. Review on methicillin-resistant Staphylococcus pseudintermedius. J Antimicrob Chemother 2011;66:2705 2714. 4. Siak M, Burrows AK, Coombs GW et al. Characterization of meticillin-resistant and meticillin-susceptible isolates of Staphylococcus pseudintermedius from cases of canine pyoderma in Australia. J Med Microbiol 63:1228 1233. 5. Ravens PA, Vogelnest LJ, Ewen E et al. Canine superficial bacterial pyoderma: evaluation of skin surface sampling methods and antimicrobial susceptibility of causal Staphylococcus isolates. Aust Vet J 2014;92:149 155. 6. Bannoehr J, Guardabassi L. Staphylococcus pseudintermedius in the dog: taxonomy, diagnostics, ecology, epidemiology and pathogenicity. Vet Dermatol 2012;23:253 266, e251 252. 7. Bannoehr J, Franco A, Iurescia M et al. Molecular diagnostic identification of Staphylococcus pseudintermedius. J Clin Microbiol 2009;47:469 471. 8. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial disk and dilution susceptibility tests for bacteria isolated from animals. 2nd informational supplement CLSI VET01-S2. CLSI, Wayne, PA, 2013. 459

9. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing. 22nd informational supplement CLSI M100-S22. CLSI, Wayne, PA, 2012. 10. Bemis DA, Jones RD, Videla R et al. Evaluation of cefoxitin disk diffusion breakpoint for detection of methicillin resistance in Staphylococcus pseudintermedius isolates from dogs. J Vet Diagn Invest 2012;24:964 967. 11. Maaland MG, Papich MG, Turnidge J et al. Pharmacodynamics of doxycycline and tetracycline against Staphylococcus pseudintermedius: proposal of canine-specific breakpoints for doxycycline. J Clin Microbiol 2013;51:3547 3554. 12. Fuchs PC, Jones RN, Barry AL. Interpretive criteria for disk diffusion susceptibility testing of mupirocin, a topical antibiotic. J Clin Microbiol 1990;28:608 609. 13. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing. 17th informational supplement CLSI M100-S17. CLSI, Wayne, PA, 2007. 14. Murakami K, Minamide W, Wada K et al. Identification of methicillinresistant strains of staphylococci by polymerase chain reaction. J Clin Microbiol 1991;29:2240 2244. 15. Griffeth GC, Morris DO, Abraham JL et al. Screening for skin carriage of methicillin-resistant coagulase-positive staphylococci and Staphylococcus schleiferi in dogs with healthy and inflamed skin. Vet Dermatol 2008;19:142 149. 16. Boost MV, O Donoghue MM, James A. Prevalence of Staphylococcus aureus carriage among dogs and their owners. Epidemiol Infect 2008;136:953 964. 17. Gharsa H, Ben Slama K, Gomez-Sanz E et al. Antimicrobial resistance, virulence genes, and genetic lineages of Staphylococcus pseudintermedius in healthy dogs in Tunisia. Microbiol Ecol 2013;66:363 368. 18. Rubin JE, Chirino-Trejo M. Prevalence, sites of colonization, and antimicrobial resistance among Staphylococcus pseudintermedius isolated from healthy dogs in Saskatoon, Canada. J Vet Diagn Invest 2011;23:351 354. 19. Iverson SA, Brazil AM, Ferguson JM et al. Anatomical patterns of colonization of pets with staphylococcal species in homes of people with methicillinresistant Staphylococcus aureus (MRSA) skin or soft tissue infection (SSTI). Vet Microbiol 2015;176:202 208. 20. Paul NC, Bargman SC, Moodley A et al. Staphylococcus pseudintermedius colonization patterns and strain diversity in healthy dogs: a cross-sectional and longitudinal study. Vet Microbiol 2012;160:420 427. 21. Mouney MC, Stiles J, Townsend WM et al. Prevalence of methicillin-resistant Staphylococcus spp. in the conjunctival sac of healthy dogs. Vet Ophthalmol 2015;18:123 126. 22. Godbeer SM, Gold RM, Lawhon SD Prevalence of mupirocin resistance in Staphylococcus pseudintermedius. J Clin Microbiol 52:1250 1252. 23. Swenson JM, Wong B, Simor AE et al. Multicenter study to determine disk diffusion and broth microdilution criteria for prediction of high- and low-level mupirocin resistance in Staphylococcus aureus. J Clin Microbiol 2010;48:2469 2475. 24. Rubin JE, Ball KR, Chirino-Trejo M. Antimicrobial susceptibility of Staphylococcus aureus and Staphylococcus pseudintermedius isolated from various animals. Can Vet J 2011;52:153 157. 25. Watson AD, Maddison JE. Systemic antibacterial drug use in dogs in Australia. Aust Vet J 2001;79:740 746. (Accepted for publication 20 April 2016) BOOK REVIEW Clinical reasoning in small animal practice. JE Maddison, HA Volk and DB Church. Wiley Blackwell, 2015. 208 pages. A$66.95. ISBN 9781118741757 The transition to practice for vets in the early stages of their careers represents a fundamental shift in the approach to veterinary medicine. Theoretical knowledge of disease processes is useless unless it can be applied pragmatically to diagnose clinical problems. Clinical reasoning aims to enable clinicians and students to put that knowledge to good use in a problem-based approach to diagnosis. A black-and-white paperback handbook, Clinical reasoning is not packed with detailed pathophysiology and has scant images. These features are not flaws; rather, they focus the reader on the aims of the book: a step-by-step approach to disease processes defining and refining the problem, location, system and lesion. The formula is applied to the broad range of presenting complaints seen in practice, with broad chapter titles such as Weight loss and Gait abnormalities. This simplistic approach supports the thorough evaluation and re-evaluation of the clinical picture of a patient. The authors approach encourages the reader to continually pose the question Does this make sense? when assessing a patient and deciding on the next diagnostic step. Downsides of the book are primarily the result of formatting that doesn t support its use as a quick reference (something I overcame with Post-it notes). The minimalistic formatting of tables makes them difficult to scan for relevant information, while flow charts, which are used to excellent effect in many chapters, are conspicuously absent in others. Overall, Clinical reasoning is a useful resource for the clinician, especially when faced with challenging diagnostic cases. Its use will help practitioners focus their approach and avoid missing something early on in a case, saving on unhelpful diagnostic tests. As a new graduate, I have found this text useful in clinical practice so far, and am sure it will get even more use with time. While of great use to recent graduates, this book would also assist any clinician who is interested in applying their knowledge in a more thorough and logical manner. Z Lederhose Zachary is a final-year veterinary science student at Charles Sturt University and the immediate past president of the Student Branch of the AVA. doi: 10.1111/avj.12518 460