Experimental Hemorrhagic Septicemia of Calves with multocida E:2: Clinical, Pathologic and Microbiologic Studies

M.O. Odugbo1* U.A. Turaki1 A.E. Itodo1 A.E.J. Okwori1 R.A. Yakubu1

Keywords Summary

Cattle – Calf – Haemorrhagic Hemorrhagic septicemia (HS) was experimentally induced in seven-month-old PATHOLOGIE INFECTIEUSE PATHOLOGIE septicaemia – Pasteurella multocida – calves (n = 2) by intratracheal inoculation of 1010 colony-forming units of six- ■ Experimental infection – Nigeria. hour log-phase Pasteurella multocida serotype E:2 to study its clinicopatho- logic features and microbiology. The was within four hours postinfection. The general continuum of clinical signs in order of manifestation was pyrexia, anorexia, dyspnea, swelling of the throat-forelimb region, tym- pany, nasal discharge, profuse salivation, lethargy, recumbency and death. The prominent lesions observed at necropsy were congestion of the lungs with consolidation and pleural adhesions of the apical lobes, pleurisy, edematous swelling of the throat and dewlap which exuded yellowish serum-like fluid, petechial and ecchymotic hemorrhages. Histologically, the lung lesions were typical of fibrinous bronchopneumonia with thickened alveolar septa, hypere- mia, edema and cellular responses of the lungs. P. multocida E:2 was re-isolated bacteriologically from the lungs, lymph nodes, liver, kidneys, spleen, edema fluid, and heart blood at necropsy. The organism was not detected in the venous blood until a few hours before death. The clinical and pathological features seen in the animals showed that there were striking similarities with P. multocida type B:2 HS. The data should help veterinarians recognize suspected cases of HS in the field.

■ INTRODUCTION countries (11). Besides type B:2, several other B (B:3,

B:4 and B:3,4) have been incriminated in recent years in sporadic 133-137 Hemorrhagic septicemia (HS) is an acute and often fatal disease outbreaks of HS in cattle and feral ruminants such as deer, elk and principally occurring in cattle and water buffaloes, but occasionally bison (15). other domesticated and wild mammals can be affected. The disease Unlike bovine HS due to P. multocida B:2, very little is known occurs almost exclusively in Asia and Africa, although outbreaks about the pathogenesis of bovine HS caused by P. multocida E:2. have been reported in Europe and North America (4, 15). HS usu- In Africa, serotype E:2 appears to be dominant, with cattle rather ally occurs as a primary , but latent infections such as than water buffaloes being mainly involved. The extent of losses trypanosomosis have reportedly precipitated clinical HS (5). Pas- from the disease are represented by mortalities of 200 to 10,000 teurella multocida serotypes B:2 (6:B) and E:2 (6:E) are the princi- cattle reported in Zambia and Zimbabwe (6, 10). Published litera- pal causes of HS. Although serotype B:2 has been mainly reported ture on HS in Africa is limited to epidemiological studies. While in Asian countries and E:2 in African countries (4, 5, 9), both the literature abounds on the pathogenesis of P. multocida type B:2, serotypes have been recovered from the disease in some African reports on the clinicopathologic features of type E:2 are fragmen- tary (12). Although definitive diagnosis of HS is currently made - 1. National Veterinary Research Institute, Vom, Plateau State, Nigeria by bacteriological identification of the causative agent, the veteri narian in the field may rely on clinical and pathological features * Corresponding author E-mail: [email protected] to tentatively diagnose the disease. The paucity of information on

Tel. (cell.): 234 80 35 95 62 89 the clinical and pathological features of HS in Africa has made trop., 2005, 58 (3) : Méd. vét. Pays Revue Élev. 133 134 Revue Élev. Méd. vét. Pays trop., 2005, 58 (3) : 133-137 ■ PATHOLOGIE INFECTIEUSE Pasteurella multocida one week to observe whether they remained afebrile and free of of free and afebrile any clinicalsignsofdiseases. remained they whether observe to week one for daily monitored were (rectal rates) respiratory signs and pulse vital temperature, calves, the of infection to Prior negative. were test, (3) (IHA) hemagglutination indirect the by determined as E:2, to levels antibody sera, preinoculation In used. E:2 bytheIHAprocedure(3)andgeldiffusion precipitintest(7). es etat h ds rpeetd 10 represented dose The extract. yeast complicated by the fact that other diseases such as anthrax, rind anthrax, as such further diseases is other that This fact difficult. the field by complicated the in disease the of diagnosis the were stained with hematoxylin and eosin and examinedeosin and hematoxylin and were stainedwith microscop all and microns 6 to 4 at cut were Sections sectioning. for paraffin in embedding before h 24 for formalin buffered phosphate 10% in fixed were Tissues postinoculation). h (120 observation of period the of end the recorded. at necropsied and lesions euthanatized were gross calves Control and necropsied were calves the death At Necropsy procedure inocu before collected were of isolation for swabs Nasal Microbiology occurred. which at inoculation death until recorded were signs clinical and temperature rectal time after daily twice observed were calves The Clinical observations infection andthecalves that diedwerenecropsied. after daily recorded were scores Clinical control. sham-inoculated with inoculated was group One building. same the of rooms separate in housed and calvestwo of groups two to allocated were calvesFour Experimental design ally with10mlofsterileenrichedLab-Lemcobroth. 37 at rpm) (150 shaking slow with grown E:2 serotype P.multocida of isolate bovine ml 10 with intratracheally dosed were calves The Infection method of free and conditions healthy apparently in calves susceptible reared conventionally seven-month-old to Six- Experimental animals METHODS AND ■ MATERIALS 1000LD Tissues or organs obtained at necropsy were also cultured for bac for cultured also were necropsy at obtained organs or Tissues ically. as confirmed were isolates The agar. blood on teria 37 at overnight incubated agar, blood The on animals. cultured the were of swabs death until inoculation after daily and lation ians inrecognizingcasesthefield. veterinar assist to thus and calves, susceptible P.in E:2 multocida by caused HS of highlight microbiology the and and signs clinicopathologic the reproduce to designed was study preliminary This nostic systemsarepoorlydeveloped. primitive,diag surveillanceare and disease tices consequently and prac husbandry where HS regions in of mainly occurs diagnosis disease the since accurate than speculations more thus are There (4). field the in HS to analogous are disease clostridial and erpest o C for 6 hours in Lab-Lemco broth (Oxoid) enriched with 0.5% with enriched (Oxoid) broth Lab-Lemco in hours 6 for C serotype E:2 while the other group served as a as served group other the while E:2 serotype P.multocida 50 (1), while the control calves were inoculated intratrache E:2InfectioninCalves 10 colony forming unit or or unit forming colony . multocida P. type P.multocida P.multocida were were o C. ------

control calves. the in changes microscopic or gross no were There vessels. phatic in edema lym and blood of accompanyingthrombosis with tissues nodal the and fibrin had nodes were lymph vasculitis prescapular and The observed. fibers muscle the of Necroses hemorrhages. with hyperemia of showedsigns and dark was tract gastrointestinal the of lining internal The appearance. in normal were kidney and spleen the but inflamed, were ducts bile and liver The fluid. nous gelati a revealed nodes these of incision and enlarged were lymph nodes mesenteric and hepatic bronchial, prescapular, The occur. not Lobulardid capillaries. necrosis of especially thrombosis, cular vas was There lobules. most in seen were colonies bacterial tion, magnifica higher On . and macrophages of mixture were a alveoli in cells inflammatory prominent; less was alveoli in dates and there was partial necrosis of the bronchial mucosa. Fibrin exu inflammatory with filled were bronchioles and alveoli bronchi many near or few resembled process; inflammatory lesions multifocal a the of those examination, microscopic power low On applied totheadjacentparenchyma. was pressure when obvious especially material, pasty purulent of amounts copious contained Bronchi prominent. not was septa tial intersti in Fibrin spaces. filled air of place in size alveolar of foci grey-white small with lobules, red dark showedmostly lobes dated were signs observed inthecontrol. clinical No regions. forelimbs the throat, around the and in dewlap observed was swelling Edematous I). (Table death and recumbence salivation, profuse distress, respiratory anorexia, the intervals, depression, temperature, rectal time increased included signs prominent these During 120 postinfection. to up days) hours (five four hours about from lasted of calves course the clinical in The disease hours. the four about study this in lasted tion marrow was positive about 24 hours after the animals’ death. death. animals’ the after hours 24 about positive was marrow f h itroua spa a eiet Cos etos f consoli of sections Cross evident. was septa interlobular the of thickening to due lungs the the of to appearance Lobulated lungs wall. coastal right the of apical adhesion right and the pericarditis of pleurisy, lobe, consolidation addition in had calf second congestion, generalized the had calves the of one of lungs the bronchitis. While suppurative of features and thrombosis, interstitial vessel some lymph fibrinous exudation, as fibrin little diagnosed with were bronchopneumonia, with cases strewn The was hemorrhages. tissue most petechial the subcutaneous were The region lesions. dewlap conspicuous and fluid throat serogelatinous submandibular, with the in edema subcutaneous postmortem, At Necropsy findings infec of route intratracheal the observedvia period incubation The Clinical observations ■ RESULTS control calves. the of tissues other any or blood from isolated not was multocida until negative were blood of 60 the about Cultures nodes. lymph and blood P.kidney,lung, the from isolated wasliver, multocida heart spleen, differentthe at multocida course. clinical the of stages necropsy,At in rich was throat-dewlap-forelimb the of Edema postinfection. days 2-3 infection, of stages later the at secretions nasal including samples, of variety a from animals challenged the from re-isolated The challenge. to prior calves the of passages nasal the from isolated not was Pasteurellamultocida Bacteriological re-isolation th hour postinfection. hour Pasteurella E:2 inoculum was inoculum E:2 P.multocida isolation from bone from isolation P. P. ------Infection à Pasteurella multocida sérotype E:2 chez le veau

Table I Synopsis of the clinical course of hemorrhagic septicemia observed in calves following intratracheal challenge with Pasteurella multocida serotype E:2

Time Mean Mean Mean Other clinical signs (hours) temperature respiratory pulse (°C) rate/min rate/min

0 38.5 24 82 Animals look normal 4 40.2 28 88 Rough hair coat, reduced appetite, dyspnea 12 41.0 27 90 Listlessness, anorexia, mucus nasal discharge, ocular discharge, dyspnea 18 39.5 26 112 Anorexia, dyspnea, tympany, edema of dewlap and throat regions, lethargy 24 41.0 27 94 Mucus nasal discharge, profuse salivation, anorexia, increased edema of dewlap, reduction in skin turgor (dehydration), lethargy 30 41.8 34 80 Mucus nasal discharge, drooling, dyspnea, anorexia, edema of throat and dewlap, lethargy, recumbence 36 39.8 24 74 Mucus nasal discharge, dyspnea, edema of throat-forelimb region, anorexia, lethargy, recumbence (and death of one of the calves) 48 40.5 24 84 Surviving calf shows mucus nasal discharge, reduced dyspnea, edema, anorexia, lethargy 54 40.9 26 80 Same as at 48th hour 60 41.0 24 70 Mucus nasal discharge, anorexia, edema of throat-forelimb region, lethargy 72 39.8 26 84 Mucus nasal discharge, slight appetite, dyspnea, edema, tremor 78 40.5 22 104 Mucus nasal discharge, edema of dewlap, tympany, dehydration, emaciation, lethargy 84 40.5 20 108 Mucus nasal discharge, dullness, reduced appetite, diarrhea, lethargy, recumbence 96 38.8 22 80 Diarrhea, dyspnea, foamy salivation, lethargy, recumbence 102 39.9 20 72 Same as at 96th hour 120 38.8 18 70 Death of second calf

■ DISCUSSION increased rectal temperature, nasal and ocular discharges, dys- pnea, submandibular swelling and reduced appetite; an apathetic In the natural HS disease, the P. multocida organism is believed third phase in which the animal responded rather slowly with coat 133-137 to gain entry via the tonsillar region of the nasopharynx following losing luster in addition to symptoms of dyspnea, anorexia, exten- inhalation or ingestion (1, 5). In the natural disease the frequently sion of edema to dewlap and forelimb regions; and a final phase in reported signs are either the acute form of the disease with sudden which the animal showed a decrease in rectal temperature presum- ably owing to a loss of homeostatic control of temperature, severe death of the calves with no apparent clinical signs, or the subacute edematous swelling of the submandibular-dewlap-forelimb, ema- form characterized by pneumonic traits of HS. Although there are ciation, tympany, recumbence and death. The course of the disease no clear-cut differences, Rhoades et al. (14) observed that in exper- lasted between three and five days and there were various overlaps imentally induced HS, the nature of the lesions depended on the of the phases. The course of the disease generally recorded in natu- route of infection; pneumonic lesions dominated when the route of ral outbreaks is however reportedly shorter than in experimental infection was intranasal. The intratracheal route of infection used transmission suggesting that in natural field outbreaks the initial in this study closely mimicked the natural intranasal route. phases may escape notice (5). In this transmission experiment, the clinical syndrome displayed The clinical and pathological findings in the challenged animals four phases distinguishable by practitioners in the field (13): an resembled the naturally occurring cases recorded by Bastionello initial phase of normalcy in which the animal looked alert with a and Jonker (2) for P. multocida type E:2 HS. A frequent clinico- lustrous coat and no signs of disease; a subdued phase in which the pathology, which helps in the diagnosis of HS in cattle, is a sub- animal looked less alert and showed signs such as a rough haircoat, cutaneous edema with serosanguinous fluid in the throat-forelimbs trop., 2005, 58 (3) : Méd. vét. Pays Revue Élev. 135 136 Revue Élev. Méd. vét. Pays trop., 2005, 58 (3) : 133-137 ■ PATHOLOGIE INFECTIEUSE Pasteurella multocida . EDETN .. GLEGE JE, EES .. 17. Fowl 1972. P.A., serotyping for REBERS test precipitin J.E., diffusion gel : GALLERGHER K.L., HEDDLESTON 7. Rec. from avianspecies from for selected diseases of livestock. Rome, Italy, FAO, p. 49-75. (Animal (Animal 49-75. p. FAO, Italy,No health and production Rome, In: livestock. of procedures diseases septicaemia. selected laboratory for of haemorrhagic manual A of bacteriology. diagnostic Diagnosis Veterinary 1990. G.R., CARTER 3. Africa. Southern by caused septicaemia of occurrence the on report A 1981. M.R., JONKER S.S., BASTIONELLO 2. multocida B.K.T.,H.F.,1980. Type FRANCIS E CARTERSCHELS G.R., 6. 9-24. p. Press, Eds., J.M., Rutter septicaemia. C., Adlam Haemorrhagic In: 1989. M.C.L., ALWIS DE G.R., CARTER 4. In: Donachie W., Lainson F.A., Hodgson J.C., Eds., Eds., J.C., Hodgson F.A., Lainson W., ( Donachie septicaemia In: Haemorrhagic 1995. multocida M.C.L., ALWIS DE 5. 131-160. p. Press, UK, Academic region, which also characterized the present findings. Gross patho Gross findings. present the characterized also which region, animals, 3rd Edn. London, UK, Academic Press. UK, Academic London, Edn. 3rd animals, K.V.F., domestic JUBB Pathologyof 1985. P.C.,KENNEDY N., PALMER 8. and production (Animal FAO. Italy, No health Rome, 1982. B.K., GUPTA septicemia. G.R., CARTER Hemorrhagic M.C.L., ALWIS DE R.V.S., BAIN 1. REFERENCES made at autopsy from a range of numerous tissues and organs, organs, and tissues heart numerous liver,and spleen, nodes, of lymph lungs, edema, namely,throat range a from autopsy at be can made isolation bacteriological definitive A (8). of pathogens presence possible other the and findings pathological of light the in assessed be should sites these of from numbers small significance of isolation the the so pasteurellosis from suffering not calves of tracts respiratory and intestinal the from commensals as isolated be the of that interpretation noted be should tentative.It be should results disease, the of course the in calves infected isolate to possible be may it While secretions. and tissues of variety a from organism challenge the of re-isolation and presence the by denced evi as septicemia developed study this in animals challenged The monia, pleurisyandpericarditiswithmarked adhesions. pneu extensive was there hours, 72 than more was disease the of course the seen. When were hemorrhages petechial scattered few a In than more no disease. hours, 24-36 in the occurred death where of cases peracute duration the on depended lesions of extent the that showed (5) Alwis De field. the in seen HS of features logical patho of diverserange the depicting cage, rib the to lung right the of adhesion and lobe apical right the of consolidation by acterized char present, was HS of form pneumonic classical the in other complications; the less with congestion generalized had lungs the them of one in calves: two the between observed were differences Major cavity. thoracic the to limited largely were changes logical , , 107 : 135. 135. :

associated with haemorrhagic septicaemia in Zambia. Zambia. in septicaemia haemorrhagic with associated serotype B:2 and E:2 infection) in cattle and buffaloes. buffaloes. and cattle in infection) E:2 and B:2 serotype 33) P. multocida P. and J.S. Afr. Vet. Assoc. . AvianDis., E:2InfectioninCalves Pasteurella from nasopharyngeal and saliva swabs of of swabs saliva and nasopharyngeal from

81) atuel multocida Pasteurella

16 . New York, USA, London, UK, Plenum Plenum UK, London, USA, York, New . Pasteurella : 925-936. : , , 52 : 99-104. : and pasteurellosis. London, London, pasteurellosis. and type E in cattle from from cattle in E type Pasteurella multocida Pasteurella P.can multocida , Haemophilus, Pasteurella Pasteurella Pasteurella Pasteurella Vet. - - - - -

14. RHOADES K.R., HEDDLESTON K.L., REBERS P.A., 1967. 1967. P.A., REBERS comp.Med K.L., administration endotoxin from and lesions infections acute from resulting microscopic HEDDLESTON and gross septicaemia: haemorrhagic K.R., Experimental RHOADES 14. pathological signs of disease in calves infected with with infected calves in and disease clinical haemolytica (Pasteurella) of between signs Relationships 2001. pathological L., REEVE-JOHNSON 13. serotypes B and E and B serotypes 16. ZAMRI-SAAD M., SAHAREE-AZIZ A., 1990. The pathology of of pathology The 1990. A., SAHAREE-AZIZ cattle. in septicaemia haemorrhagic experimental M., ZAMRI-SAAD 16. septicaemia. haemorrhagic nized etiological serotypes of of serotypes etiological nized recog three main the of relativepathogenicity the compare to way under are 16). studies comparative5, transmission Appropriate (1, are strikingsimilaritiesbetweenHSP. multocidatypesB:2andE:2 there that show findings clinicopathological The microorganisms. of isolation precluded have may animal the of because treatment antibiotic or material, fixed formalin of submission of because ble and HpaII to discriminate B B discriminate HhaI to using analysis HpaII endonuclease and Restriction 2000. R.B., RIMLER 15. Institute, Vom, Nigeria,forpermissiontopublishthesefindings. National the of VeterinaryDirector the thank authors The Research Acknowledgments associated withHSincattle. possi not either is examination microbiological helpful where be might cases study in this in described and as clinical criteria on based morphologic diagnosis a isolation, bacterial by is HS of view,definitiveof a diagnosis point although diagnostician a From ■ CONCLUSION tures of37-39°C. tempera tropical organismat the of multiplication rapid the to due perhaps tissue marrow bone the death, from Pasteurellaisolated be after could hours 24 About findings. present the by supported as disease, the of form acute the to succumbed that animals of blood Reçu le20.05.2005,accepté07.11.2005 against cattle of Protection 1976. C.W., of antigens capsular by PENN septicaemia haemorrhagic C.K., NAGY 12. an of observation First 1994. B.M., to due septicaemia haemorrhagic of outbreak NJANPOP A., MARTRENCHAR 11. 10. LANE E.P., KOCK N.D., HILL F.W.G., MOHAN K., 1992. An An 1992. in K., pasteurellosis) MOHAN (septicaemic F.W.G., Zimbabwe. in cattle septicaemia HILL haemorrhagic N.D., of KOCK outbreak E.P., LANE 10. V.P., Res.Commun SINGH A., BISWAS multocida S.B., of serotypes Prevalent 2004. P.V., SHIVACHANDRA SRIVASTAVA S.K., SINGH A.A., KUMAR 9. B6 in Northern Cameroon. Cameroon. Northern in B6 isolated from different animal and avian species in India. India. in species avian and animal different from isolated ., ., 31 ., ., 28 :

226-233. .Res. vet. Sci. : 657-667. : Trop. Prod. Anim.Health type type A1. Revue Elev. Revue M J.Med. Microbiol , , 20 atuel multocida Pasteurella P.multocida Vet.Rec. : 249-253. : é d.v , , é Pasteurella multocida Pasteurella ., ., 149 t.Pays trop , , 49 24 (B:2, E:2, and B:3,4) B:3,4) and E:2, (B:2, : 549-552. : : 81-87. : : 97-102. : Trop. Vet Pasteurella multocida Pasteurella associated with with associated ., ., 47 ., ., : 19-20. : Mannheimia Mannheimia 8 : 1-7. : Pasteurella Pasteurella serotype serotype .Can. J. Vet. - - - -

Infection à Pasteurella multocida sérotype E:2 chez le veau Résumé Resumen

Odugbo M.O., Turaki U.A., Itodo A.E., Okwori A.E.J., Yakubu Odugbo M.O., Turaki U.A., Itodo A.E., Okwori A.E.J., Yakubu R.A. Septicémie hémorragique (Pasteurella multocida sérotype R.A. Septicemia hemorrágica experimental en terneros con E:2) expérimentale chez des veaux : étude clinique, pathologi- Pasteurella multocida serotipo E:2: estudios clínicos, patológi- que et microbiologique cos y microbiológicos

Une septicémie hémorragique (SH) a été induite expérimen- Se indujo experimentalmente una septicemia hemorrágica talement chez des veaux de sept mois (n = 2) par inoculation (HS) en terneros de 7 meses de edad (n = 2), por inocula- intratrachéale de 1010 unités formant colonies d’une culture ción endotraqueal de 1010 unidades precursoras de colonias de Pasteurella multocida sérotype E:2 de 6 h en phase de de Pasteurella multocida serotipo E:2 en fase log de 6 horas, croissance exponentielle pour étudier l’aspect clinicopatho- con el fin de estudiar las características clinico-patológicas y logique de l’infection et faire l’analyse microbiologique. La microbiológicas de la infección. El período de incubación fue période d’incubation a duré quatre heures après l’infection. de 4 horas post infección. La continuidad general de los sig- La série de signes cliniques généraux, classés par ordre de nos clínicos por orden de manifestación fue pirexia, anorexia, leur manifestation, ont été les suivants : fièvre, anorexie, dys- dispnea, inflamación de la región entre el miembro anterior pnée, gonflement de la région gorge-membres avants, tym- y la garganta, timpanismo, descarga nasal, salivación profusa, panisme, jetage, salivation abondante, léthargie, décubitus letargia, decúbito y muerte. Las lesiones prominentes observa- et mort. A la nécropsie, les lésions prédominantes observées das durante la necropsia fueron congestion de los pulmones ont été : congestion pulmonaire avec symphyse pleurale des con consolidación y aderencias pleurales de los lóbulos api- lobes craniaux, pleurésie, gonflement œdémateux du pharynx cales, pleuresía, inflamación edematosa de la garganta y epi- et du fanon avec exsudation d’un liquide jaunâtre semblable glotis, con exudados amarillentos líquidos similares al suero, au sérum, et hémorragies dermiques et ecchymotiques. L’ana- petequias y equimosis hemorrágicas. Histologicamente, las lyse histologique a révélé que les lésions pulmonaires étaient lesiones de los pulmones fueron típicas de una bronconeumo- typiques de celles de la broncho-pneumonie fibrineuse avec nía fibrosa con septos alveolares gruesos, hipermia, edema y épaississement des parois alvéolaires, congestion, œdèmes et respuestas celulares de los pulmones. Durante la necropsia, réponse cellulaire des poumons. A la nécropsie, P. multocida P. multocida E:2 fue aislada de nuevo bacteriologicamente de sérotype E:2 a été à nouveau isolé bactériologiquement des los pulmones, linfonodos, hígado, riñones, bazo, fluido ede- poumons, des nœuds lymphatiques, du foie, des reins, de la matoso y sangre del corazón. El organismo no se detectó en rate, du fluide œdémateux et du sang cardiaque. Cet agent sangre venosa hasta varias horas después de la muerte. Las pathogène n’a pas été détecté dans le sang veineux jusqu’à características clínicas y patológicas observadas en los anima- quelques heures avant la mort. Les aspects cliniques et patho- les muestran grandes similitudes con P. multocida tipo B:2 HS. logiques observés sur les animaux ont montré des ressem- Estos datos deberían ayudar a los veterinarios a reconocer los blances frappantes avec P. multocida sérotype B:2 HS. Ces casos sospechosos de HS en el campo. données devraient permettre aux vétérinaires de reconnaître les cas suspects de SH sur le terrain. Palabras clave: Ganado bovino – Ternero – Septicemia hemo- rrhágica – Pasteurella multocida – Infección experimental – Mots-clés : Bovin – Veau – Septicémie hémorragique – Pasteu- Nigeria. rella multocida – Infection expérimentale – Nigeria. 133-137 Revue Élev. Méd. vét. Pays trop., 2005, 58 (3) : Méd. vét. Pays Revue Élev. 137