A retrospective study of the cuses of morbidity nd mortlity in frmed elk (Cervus elphus) Murry R. Woodbury, John Berezowski, Jerry High Abstrct A survey of North Americn frmed elk (Cervus elphus) producers ws performed to determine the cuses of sickness nd mortlity in frmed elk nd to estimte mortlity rtes. Records over 10-yer period from 8 North Americn veterinry dignostic pthology lbortories were lso exmined nd summrized. The primry dignosis for ech record ws used to clssify diseses into ctegories such s prsitic, infectious, toxicologicl, nd neoplstic. Nonspecific trum ws the most frequently reported known cuse of mortlity in both sexes nd ll ge clsses by elk producers. Rnked on perceived economic importnce, producers cited trum, chronic wsting disese, clf scours, dystoci, pneumoni, winter tick, tuberculosis, nd grin overlod. One-yer mortlity rtes for dults nd yerlings were 2.6% nd 2.7%, respectively. Mortlity rtes for mle nd femle dult nimls were 2.4% nd 2.7%, respectively. In generl, the mjor findings of the survey mtched reported cuses for mortlity provided by elk producers. Résumé Étude rétrospective des cuses de morbidité et de mortlité du cerf rouge d élevge (Cervus elphus). Une enquête chez les producteurs nord-méricins de cerf rouge d élevge été rélisée fin de déterminer les cuses de mldie et de mortlité et d estimer les tux de mortlité. Les dossiers de 8 lbortoires nord-méricins de dignostic en pthologie vétérinire ont été exminés et résumés sur une période de 10 ns. Le dignostic primire de chque dossier été utilisé pour clsser les mldies en diverses ctégories telles que prsitire, infectieuse, toxique et néoplsique. L cuse de mortlité connue l plus souvent rpportée chez les 2 sexes et à tous âges pr les producteurs concernit les trumtismes non spécifiques. Clssées selon l importnce économique présumée, les conditions suivntes ont été citées : trumtisme, mldie débilitnte chronique, dirrhée du fon, dystocie, pneumonie, tiques d hiver, tuberculose et surchrge de grin. Les tux nnuels de mortlité pour les dultes et les fons de l nnée étient respectivement de 2,6 et 2,7 %. Les tux de mortlité pour les dultes mâles et femelles étient respectivement de 2,4 et 2,7 %. Les principux résultts de l enquête ont générlement confirmé les cuses de mortlité fournies pr les producteurs de cerf rouge. (Trduit pr Docteur André Blouin) Cn Vet J 2005;46:1108 1121 Deprtment of Lrge Animl Clinicl Sciences, Western College of Veterinry Medicine, University of Ssktchewn, 52 Cmpus Drive, Ssktoon, Ssktchewn S7N 5B4 (Woodbury, High); Albert Agriculture, Food nd Rurl Development, 116B OS Longmn Building, 6909 116 Street, Edmonton, Albert T6H 4P2 (Berezowski). This reserch ws supported by grnt from the Cnd Ssktchewn Agri-Food Innovtion Fund nd the Ssktchewn Elk Breeders Assocition. Address ll correspondence nd reprint requests to Dr. M. Woodbury; e-mil: woodbury@ussk.c Introduction In the decde from 1990 to 2000, the number of elk frms in Cnd incresed from few hundred to over 1000 (1). Previous disese surveys involved reltively few dignostic reports from reltively few elk frms (2,3). Expnsion of the elk industry provided n opportunity to lern in greter detil bout the cuses of morbidity nd mortlity in frmed elk. More detiled knowledge will permit veterinrins nd other industry professionls to mke science-bsed recommendtions for disese prevention ctivities nd mngement chnges tht will improve niml welfre nd increse productivity in the elk industry. Industry wide mesurements of morbidity nd mortlity rtes provide benchmrk estimtes of these indices. Frmers cn compre their own herds ginst these benchmrks to identify res of deficiency nd develop mngement progrms trgeted t improving their herd performnce. Scientists cn trget reserch efforts towrds developing strtegies to improve the overll performnce of cervid frms. The purpose of this project ws to report the cuses of sickness nd mortlity in frmed elk in Cnd nd the United Sttes over 10-yer period nd to estimte the ge nd sex specific mortlity rtes for the 1999 to 2000 production yer. Mterils nd methods Producer survey A set of 35 questions designed to gther observtionl dt bout mortlity rtes nd morbidity nd reproduction prmeters in frmed elk ws pretested t 2 industry 1108 Cn Vet J Volume 46, December 2005
conventions. Prototype questionnires nd interviews were given to convention prticipnts to ensure tht the questions were esily understood nd tht producers could provide the dt requested of them. The survey ws then miled to North Americn elk producers. To ensure confidentility, only the nme of the stte or province where respondents frmed elk ws requested. A rndom smple of 709 elk producers ws selected from pooled dtbse mde from membership lists of ntionl, provincil, stte, nd regionl elk frming ssocitions. After removing duplicte nmes, the smpling frme contined 1694 producers, who were then grouped by ntionlity nd smpled in proportion to the number of Cndin nd US producers in the smpling frme. The number of producers smpled reflected the number needed to detect disese with herd prevlence of 2% with 95% confidence, if only 50% of the questionnires were returned. Producer nmes were sequentilly numbered s they ppered in the dtbse; computer generted rndomized numbers were then used to select the smple. The formt of the questionnire followed Dillmn s recommendtions for mximum response to postl questionnires (4). To mximize the response rte, respondents were mde eligible for lottery drw for 5 L of n nthelmintic (Cydectin; Wyeth Animl Helth, Guelph, Ontrio). Included with the questionnire ws n explntory letter introducing the survey nd emphsizing the benefits of the study, lottery entry form, nd stmped self ddressed return envelope. Postcrd reminders were sent out to ll producers 2 nd 4 wk lter. After pproximtely 6 wk, 2nd identicl questionnire pckge ws miled to nonresponders nd postcrd reminders were miled to them 2 nd 4 wk lter. To ensure confidentility, responses were immeditely coded fter receipt nd entered into dtbse (Microsoft Access; Microsoft Corportion, Mountin View, Cliforni, USA) with no ssocition between nswers nd respondents. Dtbse entries were checked twice ginst questionnires for their ccurcy, nd the internl vlidity of the dtbse ws ssessed by compring the nswers to check questions. Dtbse errors resulting from incorrect dt entry were corrected in the dtbse. The t-risk study popultion ws strtified ccording to ge nd sex, nd mortlity rtes were clculted for ech ge nd sex clss over the 1-yer period of the study. Producers were sked to nme diseses tht cused sickness or mortlity on their frms during nd before the period of the study. Morbidity nd mortlity rtes were clculted for dults nd yerlings over the 1999 2000 production yer nd expressed s percentges. Cohort specific morbidity nd mortlity rtes for clves born in 2000 were not bsed on 1-yer periods; rther they were bsed on specific time periods of risk. For exmple, neontl mortlity rtes were clculted s proportion of those clves born during the 2000 clving yer tht died within 1 mo fter birth. Assuming tht most trum rises through niml hndling, we ttempted to determine the likelihood of n injury resulting from ny single hndling event, nd producers were sked to provide informtion bout their most recent hndling session; for exmple, wening or tuberculosis testing. Differences in proportionl rtes were tested for sttisticl significnce by chi squre nlysis t 0.05 significnce level. Summry sttistics re mostly provided in tbulr form. Crude proportions or percentges were clculted by using the number of nimls hving the element of interest, divided by the number of nimls t risk from tht element during the study period. Men proportions or percentges re frm level sttistics, tht were clculted by summing the crude proportions described bove for ech frm responding to the question nd then dividing by the number of frms. Pthology lbortory survey Forty-two veterinry dignostic pthology lbortories in the United Sttes nd Cnd were contcted nd sked to prticipte in the study. Of those lbortories willing to prticipte, 8 were selected for inclusion, bsed on the number of elk submissions they received over the period from 1990 to 2000 nd on their bility to extrct useful informtion from their records. These included lbortories in Albert, British Columbi, Colordo, Minnesot, North Dkot, Ssktchewn, nd South Dkot. Submissions tht included more thn 1 ded elk were entered s single record nd ech submission ws considered 1 disese report without regrd to size. Dt were extrcted from ech record nd coded into dtbse (Microsoft Access; Microsoft Corportion). To mintin client confidentility, submissions for pthologic exmintion were identified only by n ID number. Keystone informtion stored for ech record included submission dte, ge, sex, species, nd primry cuse of mortlity. The primry dignosis for ech record ws used to clssify records into disese ctegories, such s prsitic, infectious, toxicologicl, neoplstic, etc. In ddition, 3 pthologic dignoses were recorded for ech submission, bsed on the ntomicl loction, the pthologicl chnge, nd the etiology ssocited with ech lesion. Dtbse entries were checked twice ginst the originl records for the ccurcy of ech entry. Results Producer survey Seven hundred nd nine producers responded to the survey. Five questionnires contined unrelible informtion nd were removed from the study. The overll producer survey response rte ws 33.9% (239/704), including 34.3% (148/432) of US nd 33.5% (91/272) of Cndin elk producers. The distribution of Cndin respondents ws skewed hevily towrds the western provinces, with 96% of the responses divided between Albert (44%) nd Ssktchewn (51.8%). The Ssktchewn industry contributed 55.5% (3021/5446) of the totl nimls in the Cndin dtbse, Albert contributed 40% (2180/5446). South Dkot hd the highest response (54.5%) from US stte, followed by Wisconsin (54.5%) nd Knss (46.2%). However, Minnesot contributed survey informtion on the most US nimls (1393/6497 or 21.4%), followed by Cn Vet J Volume 46, December 2005 1109
Tble 1. Single yer producer-reported cuses of morbidity nd mortlity for elk of ll ges Number of Number of Number of Disese nme sick ded reports Veterinrin b Unspecified trum 9 46 43 13 Unknown 45 55 35 25 Dystoci 5 13 12 7 Pneumoni 15 14 13 13 Tuberculosis 22 118 9 9 Clf scours 19 13 8 5 Dm glcti 19 13 8 5 Kidney filure 3 4 5 5 Other (38) 91 84 77 44 Totl 229 360 210 126 My 1, 1999 to April 30, 2000 b The number of incidents in which veterinrin ws consulted for dignosis or tretment strtegies Tble 2. Single yer producer-reported cuses of morbidity nd mortlity for elk by ge group Number of Number of Number of Disese nme sick ded reports Veterinrin b Clves Unknown 22 36 14 13 Unspecified trum 2 22 18 5 Dm glcti/ bndoned clf 14 20 10 0 Clf scours 23 16 9 5 Pneumoni 13 9 9 9 Dystoci 3 9 8 3 Stillborn 0 9 5 2 Other (17) 68 26 27 17 Totl 145 147 100 54 Yerlings Unspecified trum 1 13 12 1 Unknown 16 11 10 5 Tuberculosis 0 16 3 3 Other (10) 6 14 13 7 Totl 23 54 38 16 Adults Unspecified trum 6 11 13 7 Unknown 7 8 11 7 Tuberculosis 1 102 5 5 Endometritis 3 3 4 3 Dystoci 2 4 4 4 Kidney filure 3 3 4 4 Pneumoni 2 5 4 4 Other 29 24 27 15 Totl 53 160 72 49 My 1, 1999 to April 30, 2000 b The number of incidents in which veterinrin ws consulted for dignosis or tretment strtegies Wisconsin (882/6497 or 13.6%), Colordo (759/6497 or 11.7%), nd Iow (656/6497 or 10.1%). Overll, survey respondents provided informtion bout 11 943 elk. Of the totl number, 3748 (31.4%) were live clves, 2116 (17.7%) were yerlings, nd 6079 (50.9%) were dult nimls. There were 1111 (52.5%) mle nd 1005 (47.5%) femle yerlings, nd 2832 (46.6%) mle nd 3247 (53.4%) femle dults. Producers reported 360 mortlities in elk of ll ges (Tble 1). Three hundred nd five mortlities (84.7%) were ttributed to cuse, the reminder were listed s unknown. In 60% of the reports, veterinrin hd been consulted for dignosis or tretment. One-yer mortlity rtes were similr for dult nd yerling elk, 2.6% nd 2.7%, respectively. Mortlity rtes for mle nd femle dult nimls were lso similr, 2.4% nd 2.7%, respectively. The rte for yerling mles (3.3%) ppered to be higher thn tht of yerling femles (2.0%), but the difference ws not sttisticlly significnt (P = 0.10). There were 46 producer-described cuses of morbidity, mortlity, or both, for elk of ll ges. However, 38 of these cuses were reported fewer thn 5 times over the study period nd re grouped in Tble 1 s other disese. These other diseses ccounted for 36.7% of the disese reports, which included 40.2% of the morbidity, nd 23.3% of the mortlities. Unspecified prsitism (15.3%) nd pinkeye (8.7%) ccounted for most of the morbidity from this other group. Overll, the most 1110 Cn Vet J Volume 46, December 2005
Tble 3. Hndling specific injury nd proportionl mortlity due to hndling for elk clves, yerlings, nd dults Clves Yerling heifers Yerling bulls Adult cows Adult bulls Totl Injuries Number of frms 201 166 161 198 181 227 Number t risk 3008 1147 900 3365 2205 10625 Number injured 28 12 17 25 35 117 Crude % injured 0.9 b 1.0 2.1 b,c 0.7 c 1.6 1.2 Men % injured 2.2 1.1 3.3 1.3 1.6 2.2 Rnge 0.0 100.0 0.0 50.0 0.0 100.0 0.0 33.3 0.0 50.0 0.0 100.0 Mortlity Number of ded 5 2 0 2 3 12 Crude % mortlity 0.2 0.2 0 0.1 0.1 0.1 Men % mortlity 0.8 0.4 0 0.1 0.1 0.7 Rnge 0.0 100.0 0.0 50.0 0 0.0 14.3 0.0 7.7 0.0 100.0 Cse ftlity rte Crude cse ftlity % 17.2 16.7 0 8.0 8.6 9.8 Men cse ftlity % 18.8 25 0 9.1 11.9 14.3 Rnge 0.0 100.0 0.0 100.0 0 0.0 100.0 0.0 100.0 0.0 100.0 Proportions re expressed s the percent of ll elk tht were injured or died following single hndling event during the period My 1, 1999 to April 30, 2000 b,c Sttisticlly significnt difference between groups (P 0.05) frequently reported problem ws unspecified trum, comprising 20.5% of reports. Trum ws usully ftl, resulting in deth in 46 nimls nd recoverble injury in only 9 nimls. Age specific informtion bout the cuses of elk mortlity is provided in Tble 2. Unspecified trum ws the most frequently reported helth problem in ll ge clsses of elk nd ws the 2nd most frequent known cuse of mortlity in yerlings nd dults. Hndling relted injury nd mortlity proportions for elk clves, yerlings, nd dults re provided in Tble 3. Proportions re expressed s the percent of ll elk tht were injured or died following the lst hndling event reclled by the producer. Yerling bulls suffered proportiontely more injuries (2.1%) thn did the other ge nd sex clsses, but the difference ws significnt only when compred with dult cows (P = 0.003) nd clves (P = 0.008). Clf mortlity ws clculted over 4 different time periods from birth to 1 y of ge: Neontl mortlity (4.9%) ws the proportion of ll clves born live tht died before July 1st; summer mortlity (1.4%) ws the proportion of clves live t July 1st tht died before wening; wening mortlity (0.3%) ws the proportion of elk clves live t wening tht died within 1 mo of wening; nd postwening mortlity ws the proportion of clves live 1 mo postwening tht died by 1 y of ge (1.2%). Ech period ws significntly different from the other (P 0.0001), except for the summer nd postwening periods (P = 0.90). Two hundred nd forty respondents nswered the question: Hve you ever hd 1 of the following diseses in your elk? Of the 17 disese conditions presented in the question, winter tick ws most commonly mentioned (23.8%), followed by clf scours (22.1%), grin overlod (14.2%), nd pneumoni (12.1%). Other prsitic diseses reported were lungworm (7.1%), liver fluke (6.7%), nd meningel worm (1.3%). Pinkeye ws mentioned by 4.6% of respondents nd 4.6% climed tht they hd experienced blot on their frm. From list of 21 diseses, respondents were sked to choose ) the single disese they thought ws most economiclly importnt to individul elk frming opertions nd b) the one they considered the most economiclly importnt to the elk industry. Diseses were rnked ccording to the number of respondents selecting ech disese s most importnt. With regrd to individul opertions, trum (nonspecific) ws cited most often from 142 responses, followed in descending order of frequency by chronic wsting disese (CWD), clf scours, dystoci, pneumoni, nd winter tick. Tuberculosis nd grin overlod were rnked 7th nd intestinl prsites, 8th. Liver fluke ws 9th nd cpture myopthy, lungworm, nd nutritionl disese were mentioned 10th most often. Another 8 diseses shred the remining votes eqully. One hundred nd ninety respondents rnked diseses ccording to their importnce to the overll industry. Chronic wsting disese ws mentioned most often, followed by tuberculosis, Johne s disese, clf scours, nd intestinl prsitism in tht order. Cpture myopthy, liver fluke, nd winter tick were the 6th most frequently mentioned diseses. The reminder of 1st plce votes were divided eqully mong bbesiosis, blckleg, brucellosis, bluetongue, nd dystoci. Pthology lbortory survey The pthology lbortory survey yielded 1077 submissions. There were 314 (29.1%) femle nd 258 (24%) mle elk submitted, nd there ws 501 (46.9%) submissions where the sex ws not recorded. Twenty-nine (2.7%) submissions were less thn term fetuses nd 49 (4.5%) were nimls less thn 24 h old. One hundred nd seventy-five (16.3%) submissions were older thn 24 h but younger thn 30 d of ge. There were 145 submissions (13.5%) from nimls 30 d but 1 y, nd 473 submissions (44.1%) from nimls 1 y; 206 submissions (19.1%) were of unknown ge. In generl, the mjor findings of the pthologic survey mtched reported cuses for mortlity provided by elk producers. Primry dignoses of pthology lbortory submissions for ll ges of elk re summrized in Tble 4. There were 94 dignoses identified in the dt set, but Cn Vet J Volume 46, December 2005 1111
Tble 4. Primry dignosis of submissions for ll ges of elk to pthology lbortories Disese Cses No dignosis 144 Trum 119 Pneumoni 88 Enteritis/dirrhe 70 Emcition 61 Septicemi 55 Abscess 40 Kidney disese 37 Liver disese 33 Prsitism 28 Liver flukes 25 Abortion 23 Grin overlod 18 Encephlitis 17 Dystoci 16 Crdic disese 15 Stillborn 14 Neoplsi 13 Johne s disese 13 Peritonitis 13 Meningitis 13 Copper deficiency 10 Other 212 Totl submissions 1077 1990 to 2000 mny cuses hd only 1 or 2 submissions, so primry dignoses with less thn 10 submissions re identified s other. The most common nonspecific primry dignosis for the cuse of deth ws either no dignosis or emcition. Emcition ws listed s cuse of mortlity when the crcss ws emcited, but no cuse for the emcition could be found by the pthologist. The 2nd most common cuse of mortlity in the pthology records ws trum. Unknown nd trum were lso the 2 most common cuses of mortlity reported by elk producers. The primry lbortory dignoses by ge group re summrized in Tble 5. Among elk ged 30 d there were 39 different dignoses identified in the dt set, but dignoses with fewer thn 3 submissions were reported s other. The most common primry dignoses were enteritis (21.2%), septicemi (12.8%), nd pneumoni (8.0%). Cuses of enteritis in elk included Escherichi coli, Rotvirus, Nemtodirus spp., Clostridium perfringens, nd cryptosporidi infections. The most importnt reported cuse of septicemi ws E. coli infection. Other, less importnt cuses included infection by Clostridium spp., Slmonell spp., nd Arcnobcterium pyogenes. The most importnt reported cuse of pneumoni ws infection by A. pyogenes, followed by Psteurell spp., E.coli, Aspergillus spp., nd Mycobcterium spp. There were 43 different dignoses identified for elk between 30 nd 365 d of ge. Dignoses with fewer thn 3 submissions were reported s other. The exceptions were listeriosis, coccidiosis, nd copper deficiency, which were included for their relevnce to other species. Pneumoni ws the most common primry dignosis (13.9%) nd unspecified trum ws the 2nd (9.0%). Other importnt primry dignoses were unspecified prsitism (6.9%) nd septicemi (4.9%). The dt set for elk 1 y contined 59 dignoses, but those ssocited with less thn 5 submissions were Tble 5. Primry dignosis of elk submissions to pthology lbortories by ge group b Disese Cses Less thn 30 dys of ge c Enteritis/dirrhe 48 Septicemi 29 No dignosis 28 Pneumoni 18 Still born 14 Emcition 13 Trum 10 Dystoci 7 Liver disese 7 Kidney disese 6 Omphlophlebitis 5 Crdic disese 3 Enteritis, necrotic 3 Myopthy 3 Non vible neonte 3 Abomsitis 2 Other (23) 25 Totl submissions 224 30 to 365 dys of ge Pneumoni 20 No dignosis 15 Trum 13 Prsitism 10 Emcition 9 Septicemi 7 Abscess 7 Enteritis/dirrhe 5 Meningitis 5 Johne s 4 Grin overlod 4 Encephlitis 3 Crdic disese 2 Listeriosis 2 Coccidiosis 2 Copper deficiency 2 Other (27) 35 Totl submissions 145 Older thn 1 yer of ge Trum 77 No dignosis 70 Pneumoni 35 Kidney disese 31 Emcition 23 Abscess 19 Liver disese 16 Enteritis/dirrhe 14 Encephlitis 13 Grin overlod 13 Neoplsi 12 Dystoci 9 Liver flukes 9 Peritonitis 9 Johne s 8 Septicemi 8 Crdic disese 7 Copper deficiency 7 Cpture myopthy 6 Liver flukes 6 Arthritis 5 Locoweed poisoning 5 Other (37) 71 Totl submissions 473 1990 to 2000 b Excluding cses with unrecorded ge (n = 206) c Including nimls 24 h old but not less thn term fetuses (n = 29) 1112 Cn Vet J Volume 46, December 2005
reported s other. The most common primry dignoses of elk pthology submissions in this ge group were trum (16.2%), followed by pneumoni (7.4%). Other importnt primry dignoses for elk 1 y were kidney disese (6.5%), bscesses (4.0%), liver disese (3.4%), nd enteritis (2.9%). Of the 133 morphologic dignoses for mortlities with lesions in the respirtory trct, the most common ws pneumoni (88/133 or 66.2%). Most frequently the etiology for the pneumoni ws unknown (36/88 or 40.9%). Of the known etiologies, A. pyogenes ws the most common (17%), followed by Psteurell spp. (6.8%). Pulmonry edem ws n importnt primry dignosis of respirtory trct lesions, but in none of these submissions ws n etiology reported. The most common morphologic dignosis of 186 elk pthology submissions with gstrointestinl lesions ws enteritis (81/186 or 43.6%). The most common etiologicl gents ssocited with enteritis were E. coli (20/81 or 24.7%), Rotvirus (7.4%) nd Clostridi spp. (8.6%). Prsitic enteritis etiologies included coccidi, Trichostrongylus sp., Strongyloides sp., Nemtodirus sp., Hemonchus sp., nd Trichurus sp. The 2nd most common etiology ssocited with gstrointestinl lesions ws grin overlod (9.7%). Johne s disese ws lso importnt in cusing morbidity in elk (7.0%). The most common prsites reported in 75 submissions where the primry cuse of mortlity ws prsitism were liver flukes (26/75 or 34.7%), including F. mgn nd D. dendriticum. Other prsites reported included coccidi (5/75), Trichostrongylus sp. (4/75), Trichuris sp. (3/75), Bbesi sp. (2/75), Nemtodirus sp. (2/75), tpeworm (3/75), Hemonchus sp. (1/75), Srcocystis sp. (1/75), Cephenemyi sp. (1/75), nd ticks (1/75). Encephlitis ws the most common (17/45 or 37.8%) morphologic dignosis for 45 pthology submissions showing centrl nervous system lesions, followed by meningitis (12/45 or 26.7%). Etiologies were often not reported for encephlitis (12/45), but those tht were included infection by E. coli nd A. pyogenes, nd prsitism by Eleophor schneiderii. Cuses of meningitis were likewise infrequently recorded, but E.coli (4/12) nd P. multocid (1/12) were found. Other importnt primry dignoses ssocited with centrl nervous system lesions were locoweed poisoning (8/45) nd spongiform encephlopthy (3/45). Of the 280 primry dignoses ssocited with infectious disese, septicemi (55/280 or 19.6%), followed by pneumoni (43/280 or 15.4%), enteritis (45/280 or 16.1%), nd bscesses (38/280 or 13.6%) were the most common. Etiologies ssocited with septicemi were lrgely unrecorded (24/550) but included most commonly E. coli (17/55), followed by Clostridium spp. (4/55), A. pyogenes (2/55), Slmonell spp. (2/55), nd Listeri spp. (2/55). Pneumoni ws most commonly ssocited with A. pyogenes (15/43), unidentified bcteri (7/43), Psteurell spp., Aspergillis spp. (6/43), Mycobcterium spp. (2/43), Streptococcus spp. (1/43), Aeromons hydrophili (1/43), nd E. coli (1/43). Abscesses were mostly not ttributed n etiology (24/38). Those tht were were ttributed most commonly to A. pyogenes (9/38), followed by unspecified bcteri nd fungl gents. Infectious enteritis ws most frequently ssocited with E. coli (20/45), followed by Rotvirus (7/45), C. perfringens (5/45), nd unidentified viruses (6/45) or bcteri (5/45). Discussion Producer survey The response rte nd the proportionl numbers of elk represented from Albert nd Ssktchewn ccurtely reflect the distribution of frmed elk in Cnd in 1999 to 2000. Cndin inventory records for the yer 2000 show tht Albert hd 47.9% of Cnd s elk herd nd Ssktchewn hd 41.9% (1). Elk in Ssktchewn re somewht over represented t 55% of the surveyed Cndin elk, but in the uthors opinion, mngement techniques nd feeding prctices do not differ pprecibly between the 2 provinces. The US smples were lso selected proportiontely, but they cn be ssumed to reflect wider rnge of geogrphic influences on morbidity nd mortlity, such s climte nd feed type, thn did the Cndin smples. However, mjor industry problems, such s hndling-relted trum, re lrgely independent of regionl influences on the incidence of infectious disese, such s climte. The cuse of most mortlity ws unknown or due to unspecified trum (Tble 1). Similr findings regrding the importnce of trum s cuse of mortlity hve been reported elsewhere (3). However, in our survey, trum ws ssocited with the most individul mortlities, only in clves (Tble 2). Aside from tuberculosis, the cuse of most producer reported mortlities ws unknown. There my hve been severl resons why producers did not know the cuse of their elk mortlities, including filing to employ veterinrin to perform postmortem dignosis on ded nimls. The use of veterinrins ws highly vrible mong individul elk producers, but veterinrins were consulted for 60% of disese occurrences. Nine outbreks of tuberculosis involving 118 mortlities were reported, mking this disese the primry cuse of producer reported individul elk mortlity in North Americ in 2000. This finding ws not supported by our pthology records survey results, lthough this my be becuse submissions tht included more thn 1 ded elk were entered s single record into the lbortory dtbse nd ech submission ws considered 1 disese incident without regrd to size. In our producer survey, dult tuberculosis ccounts for lmost 10 times s mny mortlities s trum. Interestingly, tuberculosis ws lso reported to hve cused the most yerling deths. It is uncertin whether deths ttributed by producers to tuberculosis were ctully cused by disese or were, in fct, postmortem findings subsequent to tuberculosis control slughter progrms. Although tuberculosis is certinly n importnt cuse of disese in elk, it tends to cluster within herds nd in some yers, it my be infrequently reported, depending on surveillnce ctivity. Age specific injury nd mortlity rtes indicte tht yerling bulls re most t risk from injury during hndling episodes nd injure themselves more thn twice s often s yerling heifers (Tble 3). However these injuries Cn Vet J Volume 46, December 2005 1113
were pprently not s likely to be ftl nd mles were not more likely to die s result of hndling thn femles. No hndling ftlities were reported for yerling mles, which is perhps surprising given their disposition to pnic nd flight when hndled. Recll tht overll mortlity rtes for yerling mles (3.3%) is higher thn for ny other ge or sex clss, nd lthough in this study the difference is not sttisticlly significnt, it mkes empiricl sense to those who hndle elk frequently. Since trum ssocited with hndling frmed elk ws identified s n importnt known cuse of mortlity, reserch imed t improving hndling systems would be beneficil. Improved understnding of elk behvior in both confined setting nd during hndling or processing ctivities is needed. Bsic principles for hndling elk should be developed, so tht pddocks nd hndling fcilities tht re less likely to cuse injuries could be designed. Neontl mortlities were highest during the 1st month fter birth compred with those during the summer months, t wening, nd fter wening to 1 y of ge (P 0.0001). Pople et l (5) found tht 36.9% of neontl mortlities during the 1st month of life were from infectious disese. Our survey of lbortory records shows tht dirrhe, septicemi, nd pneumoni lone were responsible for 42.4% of mortlities in tht ge group (Tble 5). The rtes dropped over the summer nd t wening but incresed gin for the period from 1 mo fter wening to 1 y of ge. This increse my not hve resulted from truly higher rte but rther becuse this period ws longer thn the previous 2. Dirrhe, septicemi, nd pneumoni re common disese syndromes ssocited with neontl mortlity in other frmed species, s well s elk. The syndromes re precipitted by collge of risk fctors including infectious gents, nutrition, wether, genetics, behviorl chrcteristics of the dm, nd mngement conditions. The informtion bout risk fctors for these diseses in other frmed species should be used to estblish cusl ssocitions between the risk fctors nd disese syndromes in elk. For exmple, previous studies in deer hve identified behviorl chrcteristics of the dm, such s mismothering nd clf bndonment, s importnt to neontl mortlity (5,6). Informtion bout dehydrtion, strvtion, nd emcition problems indirectly relted to indequte mternl cre ws not cptured in our survey. Dm glcti or clf bndonment ws held responsible for 9.7% of clf morbidity nd 13.6% of clf mortlity (Tble 2), but we suspect tht elk clves dying indirectly from fctors like clf bndonment my hve been misclssified s unknown cuse, thereby underestimting the importnce of mngement-relted fctors in fwn mortlity. To compre the overll mortlity experienced between frmed cervids, 1-yer ge nd sex stndrdized mortlity rte for elk, white-tiled, fllow, nd red deer ws clculted from the results of similr surveys by the uthors. The rtes of mortlity for ech ge nd sex clss of ech species ws stndrdized ginst the combined popultion of elk nd white-tiled, red, nd fllow deer. Although the popultions of the 4 species in this study hd slightly different ge nd sex structures, white-tiled deer hd the highest mortlity rte t 13.9%. It ws 5.2 times higher thn red deer (2.7%), 2.7 times higher thn fllow deer (5.2%), nd 3.0 times higher thn elk (4.6%). This stndrdized mortlity rte for elk is lrger thn the 2.6% crude mortlity rte reported for dult elk in our study nd should only be used to compre mortlity mong species. Producer derived informtion bout on-frm morbidity focused lrgely on prsitic disese. Winter tick (Dermcentor lbipictus) ws identified by lrge proportion of elk producers nd presumbly it cused lrge problems. The life cycle of this one-host tick is such tht most of the lrvl developmentl stges occur on the niml (7). Not ll stges re feeding t the time of systemic tretment with vermectins nd not ll stges re susceptible to currently vilble cricides. These fctors nd prcticl considertions, such s ppliction of wter-bsed tretments t subzero tempertures, cn mke effective tretment difficult. Environmentl mngement of the prsite my be the best lterntive to current tretments (7). Other diseses mentioned by producers, such s grin overlod, re mngement-bsed. The prctice of strtegic feed supplementtion to optimize performnce in ntler growth or reproduction nd lcttion cn be problemtic, if producers do not understnd the hierrchicl nture of elk herd structure. The most socilly ggressive nimls re often t risk from supplementtion prctices, unless considertion is given to fctors such s dequte feeder spce, feeding frequency, nd grdul onset of supplementtion. Producer rnking of diseses importnt to themselves nd the elk industry demonstrted n wreness of existing problems, s well s potentil disese threts. By cknowledging tht hndling trum is current problem on their frms, producers hve tken the first step towrds developing welfre friendly hndling nd restrint techniques nd systems. Nming CWD, clf scours, pneumoni, nd prsitism s importnt diseses ccurtely reflects the generl disese syndromes found in North Americn pthologic surveys (1,2,8). Producers ccurtely predicted tht CWD, bovine tuberculosis, nd Johne s disese (Mycobcterium prtuberculosis infection) would be problems to the industry. The surveys were conducted in 2000, prior to the discovery of widespred CWD in wild cervids, nd before n pprecition of the mgnitude of mycobcteril disese in wild cervids in Michign (9) nd Mnitob (10). Pthology lbortory survey An ttempt ws mde to include only those records tht could be determined to hve originted from frmed elk. Although mny of the lbortories did not provide informtion clerly stting tht submissions originted from frmed elk, there ws often informtion within the body of the record tht llowed submissions to be clssified s to their origin. Records of elk heds submitted from hunter-killed elk for CWD testing, s well s from those submitted from clients who were fish nd gme officers or from those tht contined informtion indicting tht n elk ws shot with rifle, were excluded from the dtbse. It ws not possible, however, to determine the origin of ll submissions nd the dtbse must be 1120 Cn Vet J Volume 46, December 2005
considered to contin some submissions from free rnging elk. Submissions comprising more thn 1 ded elk were entered s 1 disese incident, becuse we felt tht frmers nd veterinrins would be reluctnt to submit ll ded elk from n outbrek for lbortory nlysis due to the cost of lbortory dignosis. Rther, they would submit only s mny mortlities s they felt were necessry to firmly estblish cuse of deth. Therefore, the number of elk submitted in ech disese incident ws considered to be poor estimte of the mortlity rte in n outbrek. Any inferences bout the reltive importnce of specific diseses obtined from this portion of the study must relte to the number of disese incidents, rther thn to overll mortlity ssocited with the disese. The most common nonspecific cuse of deth ws either no dignosis or emcition. To some extent, the bility of dignostic pthologist to determine cuse of deth is dictted by the dequcy of cse history informtion nd the finncil resources vilble to pursue lbortory investigtions. One could speculte tht submission with n improved cse history nd more lbortory testing might hve reclssified mny of the emcition cses. Anlysis of lbortory reported clf mortlity (Tble 5) suggests tht disese, for exmple, enteritis nd septicemi, rther thn mngement or other fctors, such s mismothering, were responsible for most mortlities in clves 30 d of ge. As noted elsewhere in this discussion, some studies in deer hve identified environmentlor mngement-relted fctors, such s mismothering nd bndonment resulting in dignosis of dehydrtion nd emcition, s being t lest s importnt s disese in cusing neontl deths (5,6). Dt were ccumulted from summry reports provided by prticipting lbortories rther thn close exmintion of cse report contents. Becuse of this, we feel tht informtion helpful in identifying lck of mternl cre or environmentl cuses of morbidity nd mortlity ws not collected, leding to defult dignosis of unknown cuse of deth. The effect of this would be the reltive overreporting of disese issues nd underreporting of mngement relted issues in neontl mortlity. No effort ws mde to seprte mortlity dignoses by pthology lbortory, perhps giving some indiction of regionl importnce of diseses, such s pneumoni. It is now understood tht erly cses of CWD were misclssified becuse the presenting signs were tht of n spirtion pneumoni or nonspecific emcition. Impired vgus nerve function in CWD results in swllowing problems, often leding to secondry spirtion pneumoni (11). Histologicl exmintion of brin is time consuming nd costly, so nimls clssified s pneumoni or nonspecific emcition my hve, in fct, been CWD cses, but there is no prcticl wy to confirm this. In summry, the highest mortlity rtes in frmed elk occurred in the neontl period from birth to 1 mo of ge nd resulted from vriety of conditions precipitted by risk fctors, including environment, mngement, nd nutrition. Epidemiologicl reserch trgeted t determining cuslly ssocited risk fctors could help to reduce the incidence of these diseses in the 1st mo of life. Elk frm productivity is lso strongly influenced by post wening mortlity, lrge proportion of which is due to hndling ssocited trum nd, therefore, preventble. Improved fcilities nd the use of pproprite hndling prctices would be of gret benefit. Acknowledgments The uthors re grteful to ech producer who shred his or her experiences by completing the reserch survey, nd to those prticipting dignostic lbortories tht generously provided dignostic records nd informtion for this project. CVJ References 1. Nixdorf R. Specilized Livestock Inventory nd Prices Updte. Industry Report for the Livestock Development Brnch. Regin: Ssktchewn Agriculture, Food nd Rurl Revitliztion. 2002, pp 32. Obtinble through Ssktchewn Agriculture, Food nd Rurl Revitliztion, 129 3085 Albert St., Regin, Ssktchewn S4S 0B1. 2. Smits JEG. Elk disese survey in western Cnd nd north western United Sttes. In: Brown RD, ed. The Biology of Deer. New York: Springer-Verlg, 1992:101 106. 3. Bruning-Fnn CS, Shnk KL, Kneene JB. Descriptive epidemiology of cptive cervid herds in Michign, USA. Vet Res 1997; 28:295 302. 4. Dillmn DA. Mil nd other self-dministered questionnires. In: Rossi PH. Wright JD, Anderson AB, eds. Hndbook of Survey Reserch. New York: Acdemic Pr, 1983:359 377. 5. Pople NC, Allen AL, Woodbury MR. A retrospective study of neontl mortlity in frmed elk. Cn Vet J 2001;42:925 928. 6. Audigé LJM, Wilson PR, Morris RS. Frmed deer herd helth nd production profiling: 4. Fctors determining reproductive success of dult hinds. In: Milne JA, ed. Recent Developments in Deer Biology. Proc 3rd Int Congr Biol Deer. Edinburgh: Moredun Res Inst, 1994:375. 7. High JC, Hudson RJ. Frming Wpiti nd Red Deer Toronto: Mosby-Yer Book, 1993:136 139. 8. Smits JEG. A brief review of infectious nd prsitic diseses of wpiti, with emphsis on western Cnd nd the northwestern United Sttes. Cn Vet J 1991;32:471 479. 9. O Brien DJ, Schmitt SM, Fierke JS, et l. Epidemiology of Mycobcterium bovis in free-rnging white-tiled deer, Michign, USA, 1995 2000. Prev Vet Med 2002;54:47 63. 10. Lees VW, Copelnd S, Rousseu P. Bovine tuberculosis in elk (Cervus elphus mnitobensis) ner Riding Mountin Ntionl Prk, Mnitob, from 1992 to 2002. Cn Vet J 2003;44:830 831. 11. Willims ES, Miller MW. Chronic wsting disese in deer nd elk in North Americ. Rev Sci Tech 2002;21:305 316. Cn Vet J Volume 46, December 2005 1121