Resurgence of leptospirosis in dogs in Ontario: recent findings

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1 ARTICLE Resurgence of leptospirosis in dogs in Ontrio: recent findings John F. Prescott, Beverly McEwen, Judith Tylor, J. Pul Woods, Anthony Abrms-Ogg, Brin Wilcock Abstrct A mrked increse in leptospirosis in dogs ws observed in 2000, prt of n incresing trend observed in previous yers in Ontrio. The highest frequency of seropositive cses occurred from September to December 2000, with the pek in November. Lrge breed dogs were prticulrly ffected. Clinicl nd clinicopthologicl dt for 31 dogs dmitted between 1998 nd 2000 to the Ontrio Veterinry College Veterinry Teching Hospitl were nlyzed. Mjor clinicl presenting fetures were cute onset of norexi, depression, fever, nd vomiting. Ninety percent of dogs, on dmission, showed biochemicl evidence of injury to severl orgns, notbly combintions in the order of kidney, muscle, pncres, nd liver. Almost ll dogs showed incresed serum ure nd cretinine levels, nd the mjority hd incresed totl cretine kinse, bilirubin, lkline phosphtse, nd leukocytosis with neutrophili. One-third were thrombocytopenic. Of dogs with liver-relted bnormlities, most hd evidence of cholestsis, with or without heptocellulr dmge. Bsed on serologic studies, in the yer 2000, the mjor serovr involved ws utumnlis, but brtislv, grippotyphos, nd pomon were lso implicted. The microscopic gglutintion test often gve confusing pttern of rectivities to the serovrs tht were tested. The high rectivity to serovr utumnlis my represent n erroneous or prdoxicl rection typicl of erly leptospirl serology. The yer 2000 ws the wrmest in Ontrio in ech of the 4 fll months (September December) of the previous decde, s well s being the third wettest in the fll period in the lst decde. The increse in cnine leptospirosis, therefore, my, in prt, reflect climte chnge. The number of positive cses declined in 2001 by bout one-third of those in 2000, but the number of submissions of ser for dignosis incresed mrkedly over previous yers. Further work is required to isolte nd to identify definitively serovrs involved in resurgent cnine leptospirosis nd the common sources for dogs. Résumé Résurgence de l leptospirose chez le chien en Ontrio : fits récents. Une forte ugmenttion de l leptospirose chez le chien été observée en 2000, s insérnt dns une tendnce à l ugmenttion observée u cours des nnées précédentes en Ontrio. L plus forte fréquence de cs séropositifs s est présentée entre septembre et décembre, vec un pic en novembre. Les chiens de grndes rces étient prticulièrement ffectés. Les données cliniques et clinicopthologiques de 31 chiens dmis à l Ontrio Veterinry College Veterinry Teching Hospitl entre 1998 et 2000 ont été nlysées. Les spects cliniques u premier exmen comprenient l pprition iguë d norexie, de dépression, de fièvre et de vomissements. À l dmission, 90 % des chiens montrient des indices biochimiques de dommges à plusieurs orgnes, notmment des tteintes combinées pr ordre décroissnt de fréquence des reins, des muscles, du pncrés et du foie. Presque tous les chiens montrient un ccroissement des tux d urée et de crétinine sériques et l mjorité présentient une ugmenttion de l crétine kinse totle, de l bilirubine, de l phosphtse lcline insi qu une leucocytose vec neutrophilie. Le tiers présentient une thrombocytopénie. Prmi les chiens présentnt des nomlies reliées u foie, l pluprt vient une cholestse, vec ou sns dommges héptocellulire. En se bsnt sur les études sérologiques, en l n 2000, l mjorité des sérotypes impliqués étient utumnlis, mis brtislv, grippotyphos et pomon étient ussi impliqués. Le test d gglutintion microscopique donnit souvent un motif enbrouillé fce ux réctivités des sérotypes testés. L forte réctivité u sérotype utomnlis pourrit représenter une réction erronée ou «prdoxle» typique du début de l sérologie de l leptospirose. L n 2000 été le plus chud des dix dernières nnées en Ontrio u cours de chcun des 4 mois d utomne (septembre décembre) ce fut ussi le 3 e utomne le plus pluvieux de l même période. L ugmenttion de leptospirose cnine peut pr conséquent être reliée en prtie u chngement climtique. Le nombre Deprtment of Pthobiology (Prescott, Tylor, Wilcock); Animl Helth Lbortory (McEwen); Deprtment of Clinicl Studies (Abrms-Ogg, Woods), University of Guelph, Guelph, Ontrio N1G 2W1. Address correspondence to Dr. John F. Prescott; emil prescott@uoguelph.c. Reprints will not be vilble from the uthors. Cn Vet J Volume 43, December

2 de cs positifs diminué d environ un tiers en 2001 pr rpport à 2000 mis le nombre de sérums soumis pour dignostic ugmenté de fçon mrquée pr rpport ux nnées ntérieures. Des recherches dditionnelles sont nécessires pour isoler et identifier définitivement les sérotypes impliqués dns l résurgence de l leptospirose cnine insi que les sources les plus fréquentes chez le chien. (Trduit pr Docteur André Blouin) Cn Vet J 2002;43: Introduction Leptospirosis hs incresed in dogs in the United Sttes (1 7), Québec (8,9), nd Ontrio (10 13) in the lst few yers. The serovrs minly involved in cnine leptospirosis re no longer cnicol nd icterohemorrhgie, s reported before the 1970s (14,15); they now include grippotyphos nd pomon s the most common serovrs (1 13), lthough brtislv (16) nd possibly utumnlis (12) re sometimes the infecting serovrs. The reson for the increse of leptospirosis in dogs nd the chnge in the serovrs involved my be the incresed nd endemic infection of urbn wildlife (notbly rccoons, skunks) with leptospirosis, combined with incresed numbers of urbn wildlife nd n incresing index of suspicion by veterinrins, thus promoting serologicl testing, s well s successful control by vccintion of the previously importnt serovrs. Although cnine leptospirosis is recognized to hve been incresing in Ontrio in the lst few yers (10 13), the fll of 2000 sw mrked rise in the number of cses. A mjor fctor ws probbly the wet nd exceptionlly wrm lte summer nd fll, which provided conditions tht were idel for the trnsmission of Leptospir from wildlife. The purpose of this pper is to describe some epidemiologicl fetures of the cnine infection in Ontrio, bsed on the yer 2000; the mjor clinicl nd clinicopthologicl fetures of recent cses of the disese in dogs presented to the Ontrio Veterinry College s Veterinry Teching Hospitl (VTH); nd the chrcteristic histopthologicl chnges observed. The role of urbn rccoons nd skunks s likely mjor reservoirs of infection is discussed s being mong the spects of the infection tht require better understnding. Mterils nd methods Serologicl findings All cses submitted to the Animl Helth Lbortory (AHL), University of Guelph, for serologicl dignosis of cnine leptospirosis from Jnury 1998 to December 2001 were retrieved from the computerized dtbse. The microscopic gglutintion test (MAT) hd been crried out in the AHL under stndrd test conditions ginst the following serovrs: utumnlis, brtislv, cnicol, grippotyphos, icterohemorrhgie, nd pomon. For seroepidemiologicl purposes, titers 40 were regrded s negtive, from 80 to 160 s suspicious, nd 320 s positive for the prticulr serovr tested. Breed of dog nd dte of serum submission were recorded. Differences between seropositive nd nonseropositive cnine cses by serovr nd yer were nlyzed by Person s chi-squre nd Fisher s exct test. Clinicl nd clinicopthologicl findings Clinicl nd clinicopthologicl dt for 31 dogs dmitted in 1998, 1999, nd 2000 to the VTH, with n eventul dignosis of leptospirosis were nlyzed. Criteri for dignosis were MAT of 320 to one or more serovrs, nd clinicl illness comptible with leptospirosis with no lterntive dignosis. Clinicl signs on presenttion were recorded. Prmeters of clinicopthologicl chnge were ssessed by stndrd methods; the dt recorded were those of the initil smples tken t the time of dmission. Histopthologicl findings The microscopic chnges observed in formlin-fixed, hemtoxylin nd eosin stined smples submitted s kidney biopsy specimens from 23 live dogs or ssorted tissues (kidney, liver) from 7 dogs tht hd died were recorded. The mjority of smples for which histopthologic exmintion ws performed were from those submitted to privte histopthology dignostic service. Meteorologicl dt Men temperture nd rinfll dt for the fll months of the previous decde t the Wterloo Regionl irport, bout 15 km from the Ontrio Veterinry College, were obtined from the Ontrio Climte Centre, Environment Cnd. Results Serologicl findings There ws mrked increse in the dignosis of cnine leptospirosis in Ontrio in The overll submission rte of cnine ser for the serologicl dignosis of cnine leptospirosis incresed 3.7 times in 2000 compred with 1998 (Tble 1), nd the proportion of seropositive cses in 2000 ws 2.8 times those in 1999 nd 1.6 times those in 1998 (Tble 1, Figure 1). In 2000, the seropositive cses occurred in both spring nd fll, but the highest submission rte nd frequency of seropositive cses occurred from the beginning of September to the end of December 2000, with the pek in November (Figure 2). The numbers of positive or suspicious cses declined by bout one-third in 2001, lthough the totl number of ser submitted for dignosis incresed by bout one-third. In 2001, in contrst to previous yers, there were seropositive cses every month, with the lrgest numbers of cses occurring from the beginning of October to the end of Jnury (dt not shown). Typiclly, seropositive dog exhibited positive MAT to rnge of the serovrs tested. In bout one-third of the cses, the MAT for single serovr ws 2 dilutions greter thn tht of ech of the other serovrs, but in the other two-thirds, there were 2 dilutions between 956 Cn Vet J Volume 43, December 2002

3 Tble 1. Submissions for cnine leptospirosis in Ontrio nd percent dignosis t the Animl Helth Lbortory, Number of Negtive Suspicious Positive Yer submissions N (%) N (%) N (%) (59.5) 6 (14.9) 11 (26.2) (66.7) 10 (18.5) 8 (14.8) (45.8) 20 (13.1) 63 (41.2) (47.4) 75 (35.2) 37 (17.4) Figure 1. Leptospirl microscopic gglutintion test, percentge seropositive cnine ser, by yer. Since dogs commonly rected to severl serovrs, percent dds to more thn 100. Figure 2. Number of leptospirl microscopic gglutintion test seropositive nd suspicious cnine ser by month, yer titers of ech serovr tested. Only 25 (31%) of 80 ser hd MAT in which 1 serovr hd titer 2 dilutions more thn ny of the other serovrs, proportion tht ws not different between yers. Eighteen of 24 ser from Jnury 1998 to December 2000 hd serovr utumnlis showing titers 2 dilutions more thn ny of the other serovrs. There ws significnt increse in the proportion of seropositive to seronegtive ser in 2000 compred with 1998 for serovrs utumnlis (P = ) nd icterohemorrhgie (P = 0.009), nd in 2000 compred with 1999 for serovrs utumnlis (P = ), brtislv (P = 0.006), grippotyphos (P = 0.006), nd pomon (P = 0.004). The most common breed of dog tht ws seropositive ws mixed breed (65 of 167 serologiclly positive or suspicious). The following breeds occurred 6 times: Lbrdor or golden retriever (n = 12); miniture schnuzer (n = 11); Dobermn pinscher (n = 10); Germn shepherd (n = 9); Alskn mlmute (n = 6); bichon frise (n = 6). Clinicl nd clinicopthologicl findings Dogs were presented with nonspecific signs of lethrgy (90%), inppetnce (81%), dehydrtion (52%), nd weight loss of vrible severity (29%). Other signs t presenttion included vomiting (81%), bdominl or lumbr pin (65%), polyuri/polydipsi (42%), tchypne Cn Vet J Volume 43, December

4 Tble 2. Orgn injury s indicted by biochemicl studies in 31 dogs on dmission to the Veterinry Teching Hospitl, Ontrio Veterinry College (1998, 1999, 2000) Orgn ffected ffected Number (%) of do Kidney only 3 (10) Kidney nd liver only 5 (15) Kidney nd pncres 9 (29) Liver only 2 (6) Liver nd pncres 1 (3) Liver, kidney, pncres 6 (18) Muscle 22 (71) Tble 3. Altered biochemicl nd hemtologicl chnges, with medin vlues, in 31 dogs on dmission to the Veterinry Teching Hospitl, Ontrio Veterinry College (1998, 1999, 2000) Biochemicl or hemtologicl Number (%) Medin (min-mx prmeter of dogs vlues) Reference intervl Blood ure nitrogen 29 (94) 33.2 mmol/l; mmol/l Cretinine 27 (87) 491 mol/l; mol/l Cretine kinse 22 (71) 380 U/L; U/L Totl bilirubin 21 (68) 5 mol/l; mol/l Alkline phosphtse 18 (58) 160 U/L; U/L Conjugted bilirubin 14 (45) 1 mol/l; mol/l Free bilirubin 15 (48) 4 mol/l; mol/l Lipse 12 (39) 397 U/L; U/L Amylse 10 (32) 708 U/L; U/L Gmm glutmyl trnsferse 8 (26) 4 U/L; U/L Alnine minotrnsferse 8 (26) 62 U/L; U/L Leukocytosis 18 (58) /L; /L Neutrophili 19 (61) /L; /L Anemi 14 (45) /L; /L Monocytosis 13 (42) /L; /L Thrombocytopeni 11 (35) /L; /L Totl serum protein 5 (16) 63 g/l; g/l b Totl serum protein 6 (19) 63 g/l; g/l Lymphopeni 6 (19) /L; /L Denotes n increse (35%), stiff git suggestive of rthrlgi or mylgi (35%), icterus (29%), nd lymphdenopthy (19%). Four dogs were pyrexic; renomegly ws detected in 3 dogs; nd either petechition, oculonsl dischrge, or scites ws observed in 1 dog ech. Ninety percent of dogs on dmission showed biochemicl evidence of injury to severl orgns, notbly combintions in the order of kidney, muscle, pncres, nd liver (Tble 2). Electrolyte nd minerl imblnces were observed in 87%; cid-bse disturbnces in 29%; nd ltered totl protein, lbumin, or globulins in 71%. Almost ll dogs on dmission showed incresed ure nd cretinine, nd the mjority hd incresed totl cretine kinse, bilirubin, nd lkline phosphtse, s well s leukocytosis with neutrophili (Tble 3). Thrombocytopeni ws recorded in one-third of dogs. Of dogs with liver-relted bnormlities, 32% hd evidence of cholestsis only, 26% of both heptocellulr nd cholesttic disese, nd none hd evidence of heptocellulr dmge only. Histopthologicl findings The repetble nd significnt microscopic lesions were restricted to kidney nd liver. In those cses for which histologic evlution of both orgns ws possible, lesions were lwys present in both. In the kidney, there ws widespred cute renl tubulr necrosis, chrcterized by corticl tubulr flttening, incresed bsophili, nd the ppernce of grnulr csts within tubulr lumens. There ws ptchy-to-diffuse interstitil edem, nd, in bout hlf the cses, there ws mild, multifocl-todiffuse lymphocytic interstitil inflmmtion. In those cses judged, on the bsis of histologic criteri, to hve slightly longer clinicl course, the interstitil edem ws converted to immture fibrosis nd the mgnitude of the lymphocytic infiltrte incresed. In the liver, the lesions were usully very subtle, with diffuse mrgintion of neutrophils (sometimes intermingled with lymphocytes) long the sinusoids, ccompnied by hypertrophy of Kupffer cells. The overll impression ws one of diffusely busy liver, typicl of the heptic rection to bcteremi. The hypercellulrity ws ccompnied in bout hlf the cses by widespred but subtle single cell heptocellulr necrosis, nd by n incresed number of mitotic figures within heptocytes. In some livers; presumbly with older lesions, there ws diffuse interstitil lymphocytic heptitis, mrked increse in mitotic figures, nd 958 Cn Vet J Volume 43, December 2002

5 Tble 4. Totl men monthly tempertures ( C) nd totl rinfll (mm), August through November, Wellington-Wterloo irport, Men monthly Men monthly Yer temperture ( C) rinfll (mm) other evidence of ttempted heptic regenertion; such s nisokryosis nd binucletion, nd some degree of lobulr collpse tht probbly represented sequel to extensive single cell necrosis. Meteoreologicl dt Compred with the previous decde, the yer 2000 hd the wrmest August, September, October, nd November, the 2nd highest rinfll in October, nd the 3rd highest rinfll in August, September, nd November. Men monthly tempertures nd rinfll for August through November re shown in Tble 4. The men temperture for December 2000 (-8.7 C) ws the coldest December in the decde. Discussion There hs been mjor chnge in serovrs involved in cnine leptospirosis in the United Sttes nd Cnd, from cnicol nd, to lesser extent, icterohemorrhgie in the 1950s nd 1960s (14,15) to grippotyphos nd pomon, nd, to lesser extent, brtislv (1 13,16). The decline to reltive insignificnce of cnicol nd icterohemorrhgie is likely the result of vccintion of dogs ginst these 2 serovrs, especilly in the 1970s. A recent study of the prevlence of leptospirosis in dogs in the United Sttes nd Cnd from 1970 through 1998 hs shown tht cnine leptospirosis hs resurged from the erly 1990s to rech the levels lst seen in the erly 1970s, fter which time infection cused by serovrs cnicol nd icterohemorrrhgie ws controlled by vccintion (17). Although leptospirosis hs incresed mrkedly in dogs in recent yers, there is evidence tht the new serovrs hve cused clinicl leptospirosis in dogs for mny yers, nd it my be tht leptospirosis hs been under-dignosed during the lst 2 decdes (3,10). Nevertheless, in the lte 1980s nd erly 1990s, only 1 or 2 cnine cses yer were being dignosed serologiclly in Ontrio by the forerunner of the AHL. The lrge number of cses observed in 2000 ws unprecedented nd seems to hve been the result of the conjunction of the pprent generl increse in leptospirosis in urbn wildlife reservoirs, discussed below; the unusully wrm lte summer nd fll conditions; nd the incresed submission rte to the AHL. Although the lrge number of cses in 2000 ws probbly relted to the wrmest nd 3rd wettest fll of the 1991 to 2000 decde, the generl pttern of incresed cses of cnine leptospirosis in recent yers cnnot be ttributed to fll climtic fctors (Tble 4). The pek incidence of disese in November ws lter thn the pek in October reported for cnine leptospirosis from 1980 to 1995 in New York Stte (3), gin probbly becuse of the unusul length of wrmth of the fll months. One intriguing feture ws the smll rise in cses in Februry nd Mrch, usully times of extreme cold in Ontrio, which would seem to preclude the spred of this fstidious nd environmentlly sensitive orgnism. A smll spring rise ws lso identified mong New York Stte cses (3). Most serologicl studies in the United Sttes nd Cnd implicte serovrs grippotyphos nd pomon s the min serovrs currently cusing cnine leptospirosis (1 13), bsed on the predominnt MAT, but our study identified serovr utumnlis s possible importnt serovr, which emerged prticulrly in Identifiction of the infecting serovr bsed on the MAT response erly in infection is, however, problemtic becuse of the prdoxicl effects observed in the serologicl response to erly leptospirosis (18). A prdoxicl rection occurs when the MAT shows highest rectivity to serovr(s) other thn the infecting serovr; with time, however, the mjor infecting serovr often gives the highest titer of the serovrs tested (8,18). Nevertheless, the high seroprevlence of utumnlis, especilly in 2000, is striking finding tht supports the need for isoltion nd identifiction of the custive serovrs, rther thn relying on serologicl studies to determine the infecting serovr. Serovr utumnlis hs been included mong those tested for in MAT ever since work, mny yers go, hd identified it, only on the bsis of serologic testing, s being present in dogs in Toronto (19). Tests of cnine ser for the serovr utumnlis re sometimes not done in the United Sttes (2,4), so tht this serovr my hve been missed. However, it seems possible tht rectivity to serovr utumnlis represents prdoxicl cross-rectivity between this serovr nd others, notbly pomon. Such prdoxicl cross-rectivity is well recognized in the erly serologicl response to leptospirl infection nd ws redily seen in the brod cross-rectivities observed. For exmple, Kingscote (20) consistently isolted serovr pomon from the kidneys of red foxes in southwestern Ontrio with severe lesions of interstitil nephritis; ntibodies to serovr utumnlis were present in ech of these foxes t titers equl to, nd usully exceeding, those of pomon. Others hve observed similr prdoxicl rections between utumnlis nd pomon (21). This suggestion tht erly serologicl response of dogs with leptospirosis to utumnlis represents prdoxicl rection supported by the filure to isolte utumnlis from dogs in the United Sttes or Cnd (7,10,16). No ttempt ws mde to determine vccintion histories for dogs. Anecdotl evidence is tht most dogs in Ontrio were not vccinted ginst cnicol nd icterohemorrhgie in the period described, becuse of dverse effects of these vccines nd the lck of evidence of infection cused by these serovrs; grippotyphos nd pomon vccine ws licenced for use in Cnd in 2001, but it ws not used in Ontrio, other thn in Cn Vet J Volume 43, December

6 specil instnces, before this time. Figure 1 shows the low proportion of dogs tht were positive for serovr cnicol, vccintion serovr. The coincidence of dignostic titers with typicl clinicl signs of leptospirosis supports the dignosis mde in this study. The most common clinicl presenttions of leptospirosis in the dogs in this study were nonspecific signs including lethrgy, inppetnce, vomiting nd bdominl pin, findings tht re similr to those in other reports of cnine leptospirosis (2 5,8,10,13). The stiff git nd lumbr pin suggestive of mylgi (or rthrlgi) observed in bout one-third of ffected dogs ws supported by biochemicl evidence of muscle dmge in over two-thirds. Clinicl evidence of mylgi my be subtle but importnt clue to leptospirosis in dog. Polymyositis hs been described s the min clinicl mnifesttion of leptospirosis in dog (22). Clinicopthologicl chnges were typicl of those described by others, lthough with more evidence of incresed pncretic enzymes, nd lmost invribly involved renl disese. Increses in mylse nd lipse my hve been indictive of concurrent pncretitis, loclized infrcts, or decresed renl metbolism. Only 3 nimls hd liver rther thn kidney disese. Although liver disese without kidney disese is uncommon, it my be the only mnifesttion of cnine leptospirosis (23). The decrese in thrombocytes in only one-third of ffected dogs is less thn sometimes reported, nd might reflect delyed dmission of these nimls to the referrl hospitl. The most striking feture of the histologic chnges ws the contrst between the subtlety of histologic lesions nd the reported severity of clinicl signs. In the first few cses exmined, the kidney ws described s being lmost norml nd skepticism ws expressed tht these subtle chnges of tubulr bsophili nd modest tubulr flttening were enough to explin 5 or 6 d of unrelenting renl filure. Subtle though the renl lesions were, the liver chnges were often even more so, presenting n even greter contrst to the severity of clinicl disese nd biochemicl bnormlities. Even in dogs with profound clinicl nd biochemicl evidence of liver disese, the chnges could be esily missed on routine histologic screening. While the slight diffuse sinusoidl hypercellulrity is seen in other bcteremic diseses nd in livers recting, for exmple, to brekdown in the intestinl brrier, the presence of widely scttered single cell necrosis ws distinctive feture tht seprted leptospirosis from other inflmmtory liver diseses. Single cell necrosis is lso observed in idiosyncrtic drug rections, but in those instnces, the sinusoidl neutrophili nd Kupffer cell hypertrophy, typicl of leptospirosis, re bsent. The most common breed of dog ffected ws mixed breed, while other breeds commonly represented included lrge breed dogs. Others hve reported lrge, herding, hound, or working mle dogs s predominnt in cses of cnine leptospirosis (2 4,6,17), presumptively ssocited with tendency to spend more time outside, but the numbers of miniture schnuzers nd bichon frises reported here indicte tht cnine leptospirosis is not restricted to ctive, sporty types of dogs. There is evidence tht leptospirl infection is being spred by rccoons in Ontrio nd Quebec (2,24,25). Rccoons re plentiful in urbn res of Ontrio, with numbers tht, in plces, my rech even s high s 100/km 2 (1 per 10m 2 ), fr exceeding numbers observed in forests or frmlnd surrounding these res (26). Forested-prks nd residentil res support the highest densities, becuse of the vilbility of nesting trees, wter, nd food in such city environments. The most commonly identified sources of serovr grippotyphos in the United Sttes re field voles nd rccoons (1). Skunks my lso be reservoir, but they re probbly more often source of serovr pomon (27). However, this serovr-host reservoir ssocition is not complete (28,29). Interstitil nephritis, in some cses with visible leptospires, is common in rccoons in the United Sttes (30). There is evidence from seroprevlence study of rccoons in Illinois tht grippotyphos infection incresed over 4-yer period from 28% in 1992 to 65% in 1993 (31), suggesting tht leptospirl infection might hve been spreding in rccoons in the yers shortly before the resurgence of cnine leptospirosis. By contrst to rccoons, skunk numbers in urbn environments re lower (6 to 12/km 2 ), more similr to those observed in rurl hbitts (32). To reduce possible trnsmission of infection from rccoons, dog owners should be wrned ginst leving food nd wter outside for their dogs, prticulrly during the lte summer nd the fll of the yer. In ddition, cnine leptospirl vccines contining serovrs grippotyphos nd pomon hve recently become vilble in Cnd nd provide effective protection ginst infection. In summry, cnine leptospirosis hs become incresingly common in recent yers in southwestern Ontrio, but it surged drmticlly in the yer 2000, suggesting tht urbn leptospirosis my become one of the dverse effects of climte chnge. Additionl work is required to define the serovrs involved directly though isoltion, rther thn indirectly through serology, nd to confirm the reltive importnce of rccoons, skunks, or other wildlife reservoirs in mintining the infection in urbn environments. The importnce of leptospirosis s zoonotic infection from dogs (33,34) emphsizes the need for veterinrins to consider recommending vccintion s likely effective nd reltively inexpensive wy of controlling the infection in dogs. Acknowledgment The uthors thnk Dr. R.C. Rostte, Ontrio Ministry of Nturl Resources, for dt relting to rccoon nd skunk popultions in Ontrio. CVJ References 1. Bolin CA. Dignosis of leptospirosis: reemerging disese of compnion nimls. Sem Vet Med Surg (Smll Anim) 1996;11: Adin CA, Cowgill LD. Tretment nd outcome of dogs with leptospirosis: 36 cses ( ). J Am Vet Med Assoc 2000; 216: Birnbum N, Brr SC, Center SA, Schermerhorn T, Rndolph JF, Simpson KW. Nturlly cquired leptospirosis in 36 dogs: serologicl nd clinicopthologicl fetures J Smll Anim Prct 1998;39: Cn Vet J Volume 43, December 2002

7 4. Rentko VT, Clrk N, Ross LA, et l. Cnine leptospirosis: A retrospective study of 17 cses. J Vet Intern Med 1992;6: Anonymous. Leptospirosis cses rising in United Sttes. J Am Vet Med Assoc 1998;212: Hrkin KR, Grtrell CL. Cnine leptospirosis in New Jersey nd Michign: 17 cses ( ). J Am Anim Hosp Assoc 1996; 32: Brown CA, Roberts AW, Miller MA, et l. Leptospir interrogns serovr grippotyphos infection in dogs. J Am Vet Med Assoc 1996;209: Klin M, Devux C, DiFrusci R, Lemy S, Higgins R. Three cses of cnine leptospirosis in Quebec. Cn Vet J 1999;40: Ribott M, Fortin M. Higgins R, Bedin S. Cnine leptospirosis: serology. Cn Vet J 2000;41: Prescott JF, Ferrier RL, Nicholson VM, Johnston KM, Hoff B. Is cnine leptospirosis underdignosed in southern Ontrio? A cse report nd serologicl study. Cn Vet J 1991: Hrinivich K, Prescott JF. Leptospirosis in two unrelted dogs. Cn Vet J 1997;38: Gillick A. Leptospirosis emerging in Ontrio. College of Veterinrins of Ontrio Updte. 1999;Jn/Feb: Prescott JF, Key D, Osuch M. Leptospirosis in dogs. Cn Vet J 1999;40: Alexnder AD, Gleiser CA, Mlnti P, et l. Observtions on the prevlence of leptospirosis in cnine popultions of the United Sttes. Am J Hyg 1957;65: Hubbert WT, Shotts EB. Leptospirosis in kennel dogs. J Am Vet Med Assoc 1966;148: Nielsen JN, Cochrn GK, Cssells JA, et l. Leptospir interrogns serovr brtislv in two dogs. J Am Vet Med Assoc 1991;199: Wrd MP, Glickmn LT, Guptill LF. Prevlence of nd risk fctors for leptospirosis mong dogs in the United Sttes nd Cnd: 677 cses ( ). J Am Vet Med Assoc 2002;220: Fine S, Adler B, Bolin C, Perolt P. Leptospir nd Leptospirosis, 2nd ed. Melbourne, Austrli: MedSci, Kingscote B, Tittiger F. Serologicl survey of dogs from Toronto for leptospirl ntibodies. Cn Vet J 1976;17: Kingscote BF. Leptospirosis in red foxes in Ontrio. J Wildlife Dis 1986;22: Clrk LG, Kresse JI, Mrshk RR, Hollister CJ. Leptospir pomon infection in n estern red fox (Vulpes fulv fulv). Nture (Lond) 1960;188: Poncelet L, Fontine M, Bllignd M. Polymyositis ssocited with Leptospir ustrlis infection in dog. Vet Rec 1991;129: Bishop L, Strndberg JD, Adms RJ, Brownstein DG, Ptterson R. Chronic ctive heptitis in dogs ssocited with leptospires. Am J Vet Res 1979;40: Wrshwsky B, Lindsy R, Artsob H. Leptospirosis confirmed in three trppers in the Middlesex-London heth unit re. Publ Helth Epidemiol Rep Ontrio 1998;9: Mikelin I, Higgins R, Lequient M, et l. Leptospirosis in rccoons in Quebec: 2 cse reports nd seroprevlence in recretionl re. Cn Vet J 1997;38: Rostte RC. Mngement of rccoons (Procyon lotor) in Ontrio, Cnd: Do humn interventions nd disese hve signficnt impct on rccoon popultions? Mmmli 2000;64: McGown JE, Krstd L. Field nd lbortory studies of skunks, rccoons nd groundhogs s reservoirs of Leptospir pomon. Cn Vet J 1965;6: Abdull PK, Krstd LH, Fish NA. Investigtion of leptospirosis in wildlife in Ontrio. Cn J Pub Hlth 1962;53: Alexnder AD, Flyger V, Hermn YF, McConnell SJ, Rothstein N, Yger RH. Survey of wild mmmls in Chespeke By re for selected zoonoses. J Wildlife Dis 1972;8: Hmir AN, Hnlon CA, Niezgod M, Rupprecht CE. The prevlence of interstitil nephritis nd leptospirosis in 283 rccoons (Procyon lotor) from 5 different sites in the United Sttes. Cn Vet J 2001;42: Mitchell MA, Hungerford LL, Nixon C, et l. Serologic survey for selected infectious disese gents in rccoons from Illinois. J Wildlife Dis 1999;35: Brodfoot JD, Rostte RC, O Lery DT. Rccoon nd skunk popultion models for urbn disese control plnning in Ontrio, Cnd. Ecol Applict 2001;11: Brkin RM, Glosser JW. Leptospirosis-n epidemic in children. Am J Epidemiol 1973;98: Wong ML, Kpln S, Dunkle LM, Stechenberg BW, Feigin RD. Leptospirosis: A childhood disese. J Peditrics 1977;90: BOOK REVIEW COMPTE RENDU DE LIVRE Prent J. The Cnine nd Feline Neurologicl Exmintion. Guelph, Ontrio, US$99.00, vilble from uthor t P.O. Box 31142, Guelph, Ontrio N1H 8K1, fx: (519) This CD is bout using the neurologicl exmintion to loclize lesions in dogs nd cts. The 6 mjor sections re mentl sttus, git nd posture, crnil nerves, posturl rections, spinl reflexes, nd pin perception. The informtion is presented s notes, photos nd grphs, videos, nd verblly. The lyout is very well designed, cler, nd uncluttered. There is extensive use of bullets to ccess dditionl informtion bout topics. Nvigtion is ided by next, previous pge, section rrows, nd menu long the bottom of the screen. There re mny wys to ccess specific informtion this CD is user friendly! Clinicl tips re included s seprte boxes nd re helpful. However, the initil informtion replyed whenever I closed tip box. The review questions provide n excellent, ctive revision, plcing the informtion into clinicl context. The computer system requirements re listed on the bck of the CD cse; the instlltion ws stright-forwrd. The progrm instlled Quick Time for video viewing, nd it dded shortcuts for tht nd the neurologicl exm onto my computer s screen without sking. Despite some minor progrm quirks (it hung up completely in the Clinicl Tips of Spinl Reflexes), the content is eductionl nd enjoyble Yes, I enjoyed this neurologicl exm lesson! The photogrphs nd videos clerly demonstrte the neurologicl problems nd the exmintion procedures. This is n exmple where using multimedi enhnces our understnding of the subject; nd here, it is well used. Dr. Prent debunks some long held illusions nd stresses the useful exmintion tests. She discusses the problems of seprting neurologicl problems from musculoskeletl diseses. In this CD, Dr. Prent is teching the clinicl dignostic skills, so tht veterinry students nd prctitioners cn use the disese informtion contined in our neurology textbooks intelligently. She does not discuss diseses. I found The Cnine nd Feline Neurologicl Exmintion to be n excellent lerning tool tht hs significntly reviewed nd updted my knowledge of the neurologicl exm nd lesion loction. This is Dr. Prent s mndte nd she hs fulfilled it very well. Reviewed by Le Stogdle, DVM, Dipl. ACVIM (smll nimls), Aesops Veterinry Cre, 620 Acdemy Rod, Winnipeg, Mnitob R3N 0E6. Cn Vet J Volume 43, December