Jason Struthers DVM
Trent Bollinger DVM
What’s killing the KCCC lambs?
…and what role are
domestic sheep playing?
Issue: Lamb mortality in an East Fraser River herd of CBS
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• Helen Schwantje: poor lamb recruitment with significantly reduced
survival of lambs past 8 weeks of age in herds that use irrigated fields.
• Regional wildlife biologists annually report lambs with lethargy,
thinness and respiratory distress.
• 1995, 2005: PM on culled lambs revealed pneumonia.
Herd lamb:ewe ratio
KCCC 23% in March of 2006
11% in August of 2010
8% in March of 2012
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Investigation: Kelly Creek-Canoe Creek herd
• Big Bar area, east of the Fraser river and northwest of Clinton, BC
• End of June to end of July 2011
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Investigation: KCCC herd
Methods:
1. Herd observations
2. Necropsy, histology
3. Ancillary diagnostics
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1) Daily herd observations
A) Assess lamb morbidity and its prevalence
B) Determine lamb:ewe ratio
C) Localize / collect dead individuals
A) Symptoms of disease:
• Increased in prevalence/severity in lambs throughout study
• From 21/06/2011 to 29/06/2011 = 4 coughing lambs on 156
observations
• Day 24 (15/07/2011) = 32-39% affected (n=31)
• Coughing*
• Diarrhea*
• Thin
• Lethargy/weakness
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9
10
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B) Necropsy n=3 (2 culled, 1 died naturally)
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B) Necropsy n=3 (2 culled, 1 died naturally)
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B) Necropsy n=3 (2 culled, 1 died naturally)
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B) Necropsy n=3 (2 culled, 1 died naturally)
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Histology: Normal lung
Histology: Lamb 1# and 2#
Lesions suggestive of Mycoplasma pneumonia
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Histology: Lamb 1# and 2#
Lesions suggestive of Mycoplasma pneumonia
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Histology: lamb 3#, which died naturally
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Histology: lamb 3#, which died naturally
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C) Ancillary diagnostics: Bacteriology and PCR
Lung culture PCR Swab culture*1
Lamb 1 2 3 1 2 3 1 2
Lab L P T L T
PDS B. trehalosi 2+
Few Pseudomonas
Pasteurella spp 1+
Pseudomonas spp
1+
S. suis 4+
P. multocida 1+
M. ovipneumoniae
(99% identity)
Not done
(ND)
- *2
AHC P. multocida 1+ Not done Not done - ND *3 ND
*1 = L is lung surface; P is pharynx; T is tympanic bullae
*2 = 1+ Lactobacillus spp; 1+ Mannheimia haemolytica
*3 = P. multocida 1+; E.coli (non-haemolytic) few
- = negative (no growth)
• Attempted Mycoplasma spp. culture on #2 (hayflick’s media) = no growth
• Polymerase chain reaction (PCR) is more sensitive
• Provides a definitive diagnosis
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• Investigate the role of Protostrongylus spp.?
• Modified Baermann technique on 77 samples
• Not significant
C) Ancillary diagnostics: lungworm
C) Ancillary diagnostics: viruses
Negative
• FA on lung: PI3, BVD, RSV, IBR
• Pan-herpesvirus PCR on lung
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• M. ovipneumoniae appears to be a primary respiratory pathogen
facilitating polymicrobial bronchopneumonia
• It is our suspicion that certain bacteria may facilitate mortality.
• Additional hypotheses of high mortality include the effects of
inclement weather and facilitated predation of sick lambs.
• Lungworm and viruses do not appear to be an issue in this herd.
Important Conclusions
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What do domestic sheep
have to do with it?
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• History of incompatibility between domestic sheep and BHS
• European settlement
• Contact associated with fatal pneumonia in BHS
• 1979 in Washington: 13/14, 26 to 80 days after contact
• 1980 in California: 37/37, 21 to 50 days after contact
• 1997-2000 in Colorado: 86 with depressed lamb survival for yrs
• Pasteurella species often incriminated
• Domestic sheep do not demonstrate signs of disease
• Role in transmission of carried pathogens?
Looking back….
Warren, 1910; Foreyt and Jessup, 1982; George et al., 2008; Besser et al., 2012a
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• 1968: 100% morbidity, fatal pneumonia in 5/14 captive BHS
• Mycoplasma on lung (Streptococcus spp too) and nasal swabs
• No Pasteurella species, No viruses
• Fastidious organism complicates identification
Besser, 2008
• MOVI often in pneumonic lung flora of lambs with early BP
• Using PCR found a consistent association of organism with BP in BHS
• + MOVI serology in sheep correlated with current or recent historical BP
problems
Woolf, 1970; Dassanayake, 2010
Making sense of MOVI
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Dassanayake, 2010: Intranasal inoculation of BHS
With M. ovipneumoniae alone…
• 100% Morbidity: lethargy, reduced appetite, intermittent cough, nasal
discharge, head shaking
• No fatal pneumonia
MOVI + inoculation of M. heamolytica A2 and A1 at day 70…
• Fatal in 1 and 5 days, respectively
Besser, 2012b: evaluated 8 distinct pneumonic epizootics
• MOVI prevalence of 95% vs 0% in healthy BHS populations
• Only agent consistently ID and with a single strain type per outbreak
• Other bacteria = mixed bag of opportunistic flora
MOVI as a primary etiology?
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MOVI: a pathogen of wildlife of domestic origin
• Contact between BHS and DS appears to result in pop-limiting
pneumonic epizootics: transmission of MOVI occurs?
• MOVI = abnormal constituent of the URT flora of BHS
• MOVI = domestic sheep normally harbor the bacteria in the NP
Besser, 2012a: BHS commingled with DS
BHS mixed with DS not carrying MOVI
• 3/4 BHS remained healthy for >100 days
Previous studies of non-discriminatory DS contact
• mortality of 98% (n=90) in BHS
Besser 2012a,b; Dassanayake, 2010; Alley, 1975 28
Any domestic sheep in Big Bar?
• Currently no domestic sheep in close proximity to the herd range
• From 2003 until 2007 there were small herds of domestic sheep with 3-4
animals/herd located directly in the KCCC range
• Unfounded anecdotal reports of free-ranging DS in the herd habitat
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Management: Why?
• 9/10 BC residents have an interest in bighorn sheep
• Publics participation in wildlife activities accounts for a net
economic value of 792$ million; a significant proportion is
directly related to CBS hunting and viewing opportunities
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Demarchi et al. 2000. Status of the
California Bighorn Sheep in BC
Management: How?
Bighorn and domestic sheep interface program (BDSIP)
• 15 km buffer
• Direct mitigation options:
• Buy-out
• Alternative livestock and relief pasture
• Domestic sheep exclusion covenant
• Profit à prendre
• Legal restrictions
• Fences
• Guardian dogs
More appropriate approaches for this herd?
• Better understanding of disease ecology required
• Antemortem sampling, ID of carriers and selective culling?
• Treatment?
• Vaccination?
Zehnder, 2006 31
Management: How?
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• Helene Schwantje, Doug Jury, and Chris Procter
• Lawrence Joiner: Landowner
• Clinton gun club: Brandy Park and Bruce Ambler
Acknowledgements
Funding partners
• BC wild sheep society
• BC Ministry of the Environment
• CCWHC
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Thank you for your attention
• Alley, M. R., Janet R. Quinlan, and J. K. Clarke. 1975. The prevalence of Mycoplasma ovipneumoniae and Mycoplasma arginini in the respiratory tract of sheep. New Zealand veterinary journal. Pp 137-141.
• Besser, Thomas et al. 2012a. Survival of Bighorn Sheep (Ovis canadensis) Commingled with Domestic Sheep (Ovis aries) in the Absence of Mycoplasma ovipneumoniae. Journal of Wildlife Diseases. 48(1): 168-172.
• Besser, Thomas et al. 2012b. Causes of Pneumonia Epizootics among Bighorn Sheep, Western United State, 2008-2010. Emerging Infectious Diseases. 18(3): 406-414.
• Besser, Thomas et al. 2008. Association of Mycoplasma ovipneumoniae infection with population-limiting respiratory disease in free-ranging Rocky Mountain bighorn sheep. J. Clin. Microbiol. 46: 423-430.
• Dassanayake, Rohana P., et al. 2010. Mycoplasma ovipneumoniae can predispose bighorn sheep to fatal Mannheimia haemolytica pneumonia. Veterinary Microbiology 145: 354-359.
• Demarchi, R.A., C.L. Hartwig, Donald A. Demarchi. March 2000. Status of the California Bighorn Sheep in British Columbia. BC environment. Wildlife Bulletin No. B-98, 67pp
• Foreyt, William J., D.A. Jessup. 1982. Fatal pneumonia of bighorn sheep following association with domestic sheep. Journal of Wildlife Diseases. 18(2): 163-168.
References
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• Lemke, S.L., and D.N. Jury. 2006. California Bighorn Sheep Population Inventory
Management Units 3-17, 3-31 and 3-32. 14 pp.
• George, Janet L., Daniel J. Martin, et al. 2008. Epidemic pasteurellosis in a Bighorn sheep
population coinciding with the appearance of a domestic sheep. Journal of Wildlife Diseases.
44(2): 388-403.
• Ongor, Hasan et al. 2011. Detection of Mycoplasma ovipneumoniae from Goats with Nasal
Discharge by Culture and Polymerase Chain Reaction. Pak Vet J, 31(x): xxx.
• Woolf, Alan, David C. Kradel and George R. Bubash. 1970. Mycoplasma isolates from
pneumonia in captive RM BHS. Journal of Wildlife Diseases. 6: 169-170.
• Warren, E. R. 1910. The mountain sheep. In E. R. Warren (ed.). The mammals of Colorado.
An account of the several species found within the boundaries of the state, together with a
record of their habits and of their distribution. G. P. Putnam’s Sons, The Knickerbocker Press,
New York and London, pp. 9–12.
References
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