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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