Objective&nbsp;To evaluate the seasonality of canine tetanus in England.Methods&nbsp;Medical records of a single referral hospital in England were reviewed. Dogs diagnosed with localized or generalized tetanus between January 2006 and June 2017 were studied.Results&nbsp;Forty-nine cases were included. The prevalence of tetanus in England was significantly higher in the winter when compared with the summer (P&nbsp;=&nbsp;0.002) and autumn (P&nbsp;=&nbsp;0.024), with the highest number of cases recorded in February.Conclusions&nbsp;The prevalence of canine tetanus in England was significantly higher in winter months, especially in February

Burkitt-Creedon, Jamie M

Ellis, Jennifer

Humm, Karen

Starybrat, Daria

Burkitt‐Creedon, Jamie M

eScholarship - University of California

UC DavisUC Davis Previously Published WorksTitleRetrospective evaluation of the seasonality of canine tetanus in England (2006–2017): 49 dogsPermalinkhttps://escholarship.org/uc/item/2rh903g2JournalJournal of Veterinary Emergency and Critical Care, 31(4)ISSN1534-6935AuthorsStarybrat, DariaBurkitt‐Creedon, Jamie MEllis, Jenniferet al.Publication Date2021-07-01DOI10.1111/vec.13068 Peer reviewedeScholarship.org Powered by the California Digital LibraryUniversity of CaliforniaReceived: 15 January 2019 Revised: 20 September 2019 Accepted: 4 October 2019DOI: 10.1111/vec.13068B R I E F C L I N I C A L COMMUN I C AT I ONRetrospective evaluation of the seasonality of canine tetanus inEngland (2006–2017): 49 dogsDaria Starybrat DVM,MVetMed, DACVECC1 JamieM. Burkitt-CreedonDVM,DACVECC2 Jennifer Ellis BSc(Hons), BVetMed1 KarenHummMA, VetMB, DACVECC,DECVECC11 Department of Clinical Science and Services,Royal Veterinary College, Hatfield, UK2 Department of Surgical and RadiologicalSciences, School of VeterinaryMedicine,University of California, Davis, California, USACorrespondenceDaria Starybrat,Hospital for SmallAnimals,Royal (Dick) School ofVeterinaryStudies,University ofEdinburgh, EasterBushCampus,MidlothianEH259RG,UK.Email: daria.starybrat@ed.ac.ukJamieM.Burkitt-Creedon is anAssociateEditor of the Journal butonlyparticipated inthepeer reviewprocess as anauthor.Presented in abstract format the18thannualEuropeanVeterinaryEmergencyandCriticalCareCongress inVenice, Italy.AbstractObjective: To evaluate the seasonality of canine tetanus in England.Methods: Medical records of a single referral hospital in Englandwere reviewed. Dogsdiagnosedwith localized or generalized tetanus between January 2006 and June 2017were studied.Results: Forty-nine cases were included. The prevalence of tetanus in England wassignificantly higher in the winter when compared with the summer (P = 0.002) andautumn (P= 0.024), with the highest number of cases recorded in February.Conclusions: The prevalence of canine tetanus in England was significantly higher inwinter months, especially in February.KEYWORDScanine tetanus, Clostridium tetani, seasons1 INTRODUCTIONCanine tetanus is an uncommon neuromuscular disease caused byneurotoxins of Clostridium tetani. Several studies in human literaturereported seasonal variation in tetanus prevalence.1–5 Although thereare no data regarding seasonality of canine tetanus, anecdotal evi-dence suggests that the prevalence of tetanus in dogs may be higherduring certain periods of the year. Knowledge of seasonal variationin occurrence of canine tetanus may direct further research towardunderstanding environmental exposure factors and animal character-istics contributing to contraction of the disease. This, in turn, couldincrease awareness of this rare disease amongveterinary professionalsand dog owners and the development of disease prevention strategiestargeting populations at risk. This study aimed to determine if there isa seasonal variation in the prevalence of canine tetanus. It was hypoth-esized that a seasonal variation in occurrence of canine tetanus existsin England.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, providedthe original work is properly cited.© 2021 The Authors. Journal of Veterinary Emergency and Critical Care published byWiley Periodicals LLC on behalf of Veterinary Emergency and Critical Care Society2 MATERIALS AND METHODSMedical records of a single small animal teaching referral hospital inEngland were reviewed. Data from canine tetanus cases presentingto the hospital between January 2006 and June 2017 were evaluatedretrospectively. Dogs diagnosed with tetanus by either a Diplomatein Emergency and Critical Care, Neurology, or Internal Medicine wereincluded in the study. Thediagnosiswasmadebasedonhistory, presen-tation, and progression of clinical signs. Dogs with characteristic localor generalized signs such as wrinkled forehead, erect ears, retractedlips, stiff gait, and generalized increase in muscle tone were included.Dogs with evidence of another neuromuscular disease were excluded.For the purpose of this study, it was assumed that the dogs were diag-nosed on the day of presentation to the hospital. The month and sea-son of the presentation were recorded, with seasons of the year beingdefined aswinter (December–February), spring (March–May), summer(June–August), and fall (September–November).J Vet Emerg Crit Care. 2021;1–4. wileyonlinelibrary.com/journal/vec 12 STARYBRAT ET AL.Age, breed, sex, weight, and date of presentation were recorded.Depending on weight on admission, dogs were categorized as small(<10 kg), medium (10–25 kg), or large (>25 kg). Data regardingmonthly caseload distribution in the hospital were recorded, andthe correlation between the caseload and the monthly distributionof tetanus cases was assessed. Information regarding monthly aver-age rainfall and temperatures in England for each month betweenJanuary 2006 and June 2017 was obtained from a governmentdatabase.aEthical approval for this study was granted by the Social ScienceResearch Ethical Review Board at the Royal Veterinary College (refer-ence URN SR2017-1392).2.1 Statistical analysisData were assessed for normality using the Shapiro–Wilk test. AKruskal–Wallis test was used to evaluate statistically significantdifferences in numbers of tetanus cases presenting to the hospi-tal between each month of the year, as well as between 4 sea-sons of the year. A Dunn–Bonferroni post hoc test was con-ducted to test pairwise comparisons. A P-value of <0.05 was con-sidered statistically significant. A Spearman’s correlation test wasused to assess relationship between the monthly prevalence ofcanine tetanus and monthly hospital caseload, average monthlyprecipitation, and average monthly temperatures in the studiedregion. Standard statistical software was used to generate statisticalcalculations.b,c3 RESULTSForty-nine cases of canine tetanus were identified and included in theanalysis. The most commonly reported breeds included crossbreeds(n=13), LabradorRetriever (n=10), BorderCollie (n=4), Boxer (n=3),Pointer (n = 3), Doberman Pinscher (n = 2), English Cocker Spaniel(n= 2), andGolden Retriever (n= 2). Data regardingweightwere avail-able for 33 of 49 dogs, of which 13 were large, 17 were medium, and3 were small. There were 8 intact females, 14 neutered females, 15intact males, and 12 neutered males. The age of the dogs ranged from10 months to 9 years (median, 4 y). Available data regarding monthlyhospital caseloadwere limited to the period betweenAugust 2006 andJune 2017. The prevalence of canine tetanus during this period wasdocumented at 0.038%. Spearman’s rank correlation test showed nocorrelation between the prevalence of canine tetanus and the hospitalcaseload (P= 0.47).a Met Office. Met Office Integrated Data Archive System (MIDAS). NCAS British Atmo-spheric Data Centre. England monthly mean temperature and England monthly rain-fall. [Internet] 2018. Available at: https://www.metoffice.gov.uk/climate/uk/summaries/datasets#yearOrdered. Accessed April 22, 2018.b SPSS, version 24, SPSS, Inc., Chicago, IL.c Microsoft Office Home and Student 2013. Microsoft Excel (version 15). Microsoft Corpora-tion, Redmond,WA.Monthly and seasonal canine tetanus prevalence is displayed in Fig-ures 1 and 2, respectively.Therewas a statistically significant difference in themonthly preva-lence in canine tetanus presentation (P = 0.048), with the highestnumber of cases seen in February (n = 11) and no cases recordedin August. There was also a statistically significant difference in casedistribution between seasons of the year (P = 0.003). A significantdifference in seasonal case distribution was noted between winterand summer (P = 0.002) and between winter and fall (P = 0.024).There was no correlation between the prevalence of tetanus andmonthly rainfall in England. There was, however, a weak negativecorrelation between the prevalence of tetanus and the averagemonthly temperatures in England (rS = –0.30, n = 138, P < 0.001;Figure 3).4 DISCUSSIONThis retrospective case series aimed to assesswhether therewas a sea-sonal prevalence of canine tetanus. The prevalence of canine tetanusin England was found to be significantly higher in winter months whencompared with summer and fall, with the highest number of casesrecorded in February. The tetanus population evaluated in this studywas similar to that described in previous retrospective studies consist-ing of predominantly medium and large breeds and a younger popula-tion of dogs.6–8The seasonality of tetanus has been reported in people in severalstudies, although findings are contradictory. In 1 study, the highestprevalence of tetanus among people living in India was in the post-monsoon season (September–December).1 The authors found that onethirdof tetanus casesoccurred in the transitionperiodbetween thehotand wet monsoon season and the cool and dry winter season. It wassuggested that this was likely related to the occupation of the affectedpeople (farmers and manual laborers), who were more likely to comeinto contact with the toxin via injuries sustained at work during thisperiod. InNigeria, higher numbers of adult tetanus have been recordedin the hot and dry season.2 The authors hypothesized that this was dueto reduced activity, increasedwearing of shoes, and increasedwashingaway of animal waste that littered the streets in wet weather. A higherprevalence of human tetanus in warmer months has also been notedin Italy, Canada, and Japan and has been associated, by some authors,with greater outdoor activity and increased exposure to soil.3–5Given these differing findings in the human data and lack of defini-tive reasoning for the seasonal variations seen, it is unclear why a sea-sonal prevalence in canine tetanus was noted in England. As therewas not a similar variation in hospital caseload over the same months,the variation in prevalence is thought to be a true finding. The cor-relation between tetanus caseload and lower temperatures suggeststhat cooler weather conditions may lead to increased canine expo-sure to C. tetani spores. One possible explanation is that mild winterweather conditions support bacterial growth and survival. A combina-tion of environmental factors, such as temperature and humidity, maystimulate favorable anaerobic conditions or production of nutrientsSTARYBRAT ET AL. 3F IGURE 1 Monthly prevalence of canine tetanus in EnglandF IGURE 2 Seasonal prevalence of canine tetanus in Englandpromoting spore germination.1 Dogs walked in England during win-ter months are often exposed to wet and muddy conditions, less pro-nounced in warmer seasons, which may predispose to increased con-tamination of woundswith soil-containing spores. Further studies aim-ing to elucidate the effect of environmental factors on the prolifera-tion of C. tetani, spore germination, and exposure of dogs to the sporeswould beworthwhile.This study has several limitations. First, a sample size calculationwas not performed prior to commencement of this study as a conve-nience study period was chosen instead. Therefore, it is possible thatunderpowering could have led to finding adifferencewhereonedid notexist (type I error), though this is generally thought to be less commonthan type II error. Second, lack of significant correlation between theprevalence of tetanus and monthly rainfall in England may be due to alow number of cases included in the study. Additionally, the effect ofactivity level, working status, and environmental exposure (urban vs.rural) of the dogs on the prevalence of tetanus could not be assesseddue to the retrospective nature of the study. Moreover, because onlya referral population was investigated, the true occurrence of caninetetanus in investigated regions may be higher as many affected dogsmay have not been referred. This, in turn, could influence the resultsof investigations on the seasonality of the disease. Furthermore, in thecurrent study, the date of diagnosis was used to evaluate the season-ality. This date, however, may not represent the date of initial signs of4 STARYBRAT ET AL.F IGURE 3 Monthly tetanus occurrence, averagemonthly temperatures (◦C), and rainfall (mm) in Englandthe disease, the identification of which would rely on owners and pri-mary care practitioners. Finally, the date of diagnosis does not reflectthe date of exposure to spores, as C. tetani has a variable incubationperiod of 3 days to 3 weeks. Therefore, although the seasonal preva-lence of canine tetanus appeared to peak in the winter months, it islikely that the actual onset of the disease process was up to a monthearlier.The prevalence of canine tetanus in Englandwas significantly higherin winter months, especially in February. Further studies could investi-gate the effect of different climates, other environmental factors, andactivity levels of exposed dogs on the prevalence of canine tetanus.ACKNOWLEDGMENTSThe authors wish to thank Dr. Elizabeth Rozanski, DVM, DACVIM,DACVECC, for her input in preparation of this manuscript, and Dr. Yu-Mei Chang, PhD, CStat, for statistical advice.CONFLICT OF INTERESTDr Burkitt-Creedon is an editor for the Journal but did not participatein the peer reviewprocess other than as an author. The authors declareno other conflict of interest.ORCIDDaria StarybratDVM,MVetMed,DACVECC https://orcid.org/0000-0001-7715-2852REFERENCES1. Bansal J, Jain R, Gaur K. Seasonal variation in non neonatal tetanus:7 years retrospective record based study. Int J Multispeciality Health.2015;4:31-35.2. Bandele EO, Akinyanju OO, Bojuwoye BJ. An analysis of tetanus deathsin Lagos. J Natl Med Assoc. 1991;83(1):55-58.3. Ashley MJ, Bell JS. Tetanus in Ontario: a review of epidemiological andclinical features of 102 cases occurring in the 10 year period 1958–1967. CanMed Assoc J. 1969;100(17):798-805.4. Pedalino B, Cotter B, Ciofi Degli Atti M, Mandolini D, Parroccini S,Salmaso S. Epidemiology of tetanus in Italy in years 1971–2000. EuroSurveill. 2002;7(7):103-110.5. Nakajima M, Aso S, Matsui H, Fushimi K, Yasunaga H. Clinical featuresand outcomes of tetanus: analysis using a national inpatient database inJapan. J Crit Care. 2018;44:388-391.6. Adamantos S, Boag A. Thirteen cases of tetanus in dogs. Vet Rec.2007;161(9):298-302.7. Bandt C, Rozanski EA, Steinberg T, Shaw SP. Retrospective study oftetanus in 20 dogs: 1988–2004. J Am AnimHosp Assoc. 2007;43(3):143-148.8. Burkitt JM, Sturges BK, Jandrey KE, Kass PH. Risk factors associatedwith outcome in dogswith tetanus: 38 cases (1987–2005). J AmVetMedAssoc. 2007;230(1):76-83.How to cite this article: Starybrat D, Burkitt-Creedon JM, EllisJ, HummKRetrospective evaluation of the seasonality ofcanine tetanus in England (2006–2017): 49 dogs. J Vet EmergCrit Care. 2021; 1–4.

Retrospective evaluation of the seasonality of canine tetanus in England (2006-2017): 49 dogs.

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