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Sheep & Goats - Eliminating Chronic Disease Using a Farmbased Approach: Caseous Lymphadenitis (CL)

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Eliminating Chronic Disease Using a Farmbased Approach: Caseous Lymphadenitis (CL) (PDF)

SARE Farmer Grant Final Report 2014

By Anne Lichtenwalner DVM PhD, University of Maine Cooperative Extension, and Animal and Veterinary Sciences

CL: What is it?

  1. “Cheesy gland”: Chronic bacterial infection Corynebacterium pseudotuberculosis
    • Stays in the immune system
    • May cause skin or internal abscesses
  2. Can be spread from animal to animal:
    • Must have skin penetration
  3. Persistent in the environmentlocation of lymph nodes on a goat
  4. Use antibody response to test for presence of bacteria in unvaccinated animals
  5. Vaccines are available; not highly effective

Corynebacterium pseudotuberculosis: lymph nodes

  1. External: Firm, dry abscesses- slow to develop
  2. Internal: Weight loss, coughing

CL: Internal abscesses (goat at necropsy)

Chest wall lifted away from lungs to show inflammation due to CL abscess.

Lung tissue with CL internal abscess (opened) showing dry exudate.

CL: How contagious is it?


  • Direct inoculation of bacteria into new host
    • Cut or ulcer, contact with exudate
    • Bites from flies that have contacted exudate
    • Rubbing on tree, etc, that has exudate on it
  • Inhalation of infected secretions
    • Sheep with bronchial lymph node abscesses: coughing
  • Milk?
    • If mammary lymph infections present
    • See more recent info (below)


  • Vaccines or antitoxins:
    • Don’t prevent or cure, but may decrease abscesses
  • Immune clearance ineffective
    • Toxins overcome normal immune defenses
  • “Hides out” inside cells
    • Uptaken by macrophages; survives and is spread to lymph nodes
  • Antibiotics
    • In vitro, many are effective
    • In vivo, nothing works: food animal limitations re antibiotics
  • Rifampin with tetracycline was useful in early infection

Judson et al, 1991. Veterinary Microbiology 27(2): 145-150.
Senturk and Temizel, 2006. Veterinary Record 159(7): 216-217

CL: How long does it last on my farm?

Non-spore former, but environmentally stable

  • C. pseudotuberculosis wasn’t killed by 4 months in soil samples containing exudate from CL abscesses, and after 11 months in sterilized soil samples (40º F, 72º F, 98 º F and ambient conditions).
  • C. pseudotuberculosis was killed after 3 hours in chlorinated tap water, but could survive up to 70 hours in distilled water.
  • Disinfectants: many are effective against CL after thorough cleaning of surfaces. However: rough surfaces such as wood may be impossible to disinfect.

petri dishCL: Can I detect or prevent it?


  • Exposed animals: PLD antibodies
    • Test based on detecting antibodies
    • “Seropositives” carry the bacteria


  • Vaccines not 100% effective
    • Boosters, accurate records needed
    • Vaccine will NOT cure, only help prevent abscesses
    • Using vaccine creates “seropositives”
  • Testing and culling seropositives: best method
    • But will this work for all farms?

Trial Methods

SARE Grant: CL in Sheep

  • Visit farm: use farm vet if possible
  • Test sheep: 0 and at least 60 days
  • Initial SHI tests done by Washington State University
  • Report results (farm ID confidential)
  • Consultation
    • Biosecurity
    • Tailor methods to farm type
    • Survey
  • SHI test method developed at UMaine lab in Orono
    • Supports local industry
    • Create easier access to vigilance methods
    • Validate CL-free status for producers

Farm types tested

  • Breeds: Many
  • Products: Fiber, meat, milk
  • Biosecurity: Varied greatly

CL status

  • 8 of 17 had positive animals at first test (47%)
    • 22% of 705 sheep tested at least once were CL+
  • 8 of 9 negative farms stayed negative (1 didn’t retest). Closed herd and good biosecurity essential
  • Inability to run test locally interfered with outcome
  • At follow-up, most of the positive farms had culled or isolated positive animals

Biosecurity: example (Farm 2)

  • Breeding for fiber and meat: Animals may travel off farm: limited or no quarantine
  • Tested “home” animals: all neg.
  • Tested “returned” animals: 1 pos.
  • Retested “home” animals: new positive

Followup: culled all positives, implemented quarantine procedures for returning animals

Trial Results

Farmer compliance

  • All farmers directly contacted said they would cull
    • Follow-through really varied. “Favorites” or great producers were unlikely to be culled.
  • Most were unwilling to replace wooden feeders or other areas where CL transmission likely.
  • Most thought their biosecurity was excellent
  • All were highly concerned and involved in the success of their flocks
  • Some of the 17 farms had camelids; none had goats

Farmers resented “buying” chronic disease

  • “Do unto others” was a strong motive


  • Prevalence higher than expected
  • Does being CL-free add to value?
    • “Caveat emptor”: Selling CL free breeding stock=value
  • Other species affected: goats, camelids
    • Be careful of guard animals: need testing, too
  • Farm type dictates whether vaccination ok
    • Reluctance to cull is common
    • Vaccination takes away possibility of testing
    • No strategy works longterm without culling
  • Biosecurity and determination dictate whether disease-free status is achievable


  • Awareness of CL increased
    • Added value of CL-free status
  • Biosecurity templates in development
    • Google Earth model may help communications about farm layout and biosecurity
  • SHI method now in Orono on a research basis
    • Project continuing studying goat dairies in 2014-5
    • Sheep testing available in 2015 if serum samples can be collected/shipped to UMAHL (no charge for testing)
  • Decision Tree: Start by knowing your status
    • Assess the cost of CL-free status for your farm
    • May not work for everyone

Outcomes: Recommendations

  • Know the CL status of your flock: retest as needed
  • Maintain closed flock/herd with high biosecurity
    • Notify visitors about biosecurity
    • Inform shearers about biosecurity
    • New or returning animals:
      • Don’t immediately mix with “home” flock
        • “nose to nose H quaranIne”
      • CL test immediately at entry and prior to release from quarantine (2 mo. later)
        • If positive, cull or sequester positives

» Retest exposed animals at 2 months: cull if +
» Keep quarantined until all negative for CL at 2 consecutive tests 2 months apart

Outcomes: Decision Tree

Decision Tree: New animal to CL- flock: genetics needed? Is source flock CL+? Yes: Don’t buy or Quarantine and test at entry and 2 mo. No: Quarantine and test at entry and 2 mo.

Outcomes: Decision Tree

Decision Tree: CL+ at end of quarantine? Yes: Slaughter or Sequester No shared spaces, feed, water, equipment; AI only (if a ram). No: Add to group Keep CL- via good biosecurity.


  • Stopped CL on several farms
    • Estimated 20% improvement in fiber yields
    • Potentially reduced carcass condemnation
  • Outreach to SR vets
    • Free testing may enhance communications
    • Help establish VCPR with farmers
  • Farmer-to-farmer:
    • Added value of CL-free stock
    • Building biosecurity awareness
  • Students
    • projects and experience

Recent Undergrad Student Theses on SR

  • Edith Kershner: Case study of sheep farms with or without CL.
  • Abigail Royer: Detecting CL using complete blood counts.
  • Amy Fish: Evaluating macrophage responses to CL.
  • Rachel Chase: Evaluating neutrophil responses to CL.
  • Cassandra Karcs: CL prevention in small ruminants.
  • Hallie Lipinski: CL and its connection to milk.
  • Anna Desmarais: Selenium and footrot prevalence.
  • Alden West: Composting effects on coccidia.
  • Alexandra Settele: Anthelmintic resistance in H. contortus
  • Amanda Chaney: Identification of internal parasites of sheep and goats
  • Caitlin Minutolo: Effect of age on susceptibility to ovine footrot.
  • Nicole Maher: CL webinar for producers
  • Casey Athanas: Pedigree analysis to help eradicate footrot.
  • Katrina Glaude: Should sheep with footrot be culled?
  • Kayla Porcelli: Biosecurity survey for footrot positive farms
  • Marie Smith: Pasture management to control parasites in small ruminants.


  • Sheep and Goat, Wool and Mohair: 1982. Research reports, Texas A and M University.
    • Augustine JL and Renshaw HW. Longevity of C. pseudotuberculosis in six Texas soils. P 102
    • Augustine JL, Richards AB, Renshaw HW. Persistence of C. pseudotuberculosis in water from various sources. P 104.
  • Assis RA, Lobato FCF, Martins NE, et al. Clostridial myonecrosis in sheep after caseous lymphadenitis vaccination. The Veterinary Record 2004;154:380-380.
  • Paton MW, Walker SB, Rose IR, et al. Prevalence of caseous lymphadenitis and usage of caseous lymphadenitis vaccines in sheep flocks. Australian Veterinary Journal 2003;81:91-95.
  • Fontaine MC, Baird G, Connor KM, et al. Vaccination confers significant protection of sheep against infection with a virulent United Kingdom strain of Corynebacterium pseudotuberculosis. Vaccine 2006;24:5986-5996.
  • Baird GJ, Malone FE. Control of caseous lymphadenitis in six sheep flocks using clinical examination and regular ELISA testing. The Veterinary Record 2010;166:358- 362.
  • Washburn KE, Bissett WT, Fajt VR, et al. Comparison of three treatment regimens for sheep and goats with caseous lymphadenitis. Journal Of The American Veterinary Medical Association 2009;234:1162-1166.


  • Collaborating Farmers of Maine
  • Collaborating Veterinarians:
    • Drs. Becky Myers Law and colleagues
    • Dr. Tammy Doughty
    • Dr. Don McLean
    • Dr. Beth McEvoy
  • NE SARE: Carol Delaney
  • Extension colleagues: Richard Brzozowski and Donna Coffin
  • Technical/lab assistance:
    • Edith Kershner, Anne Ryan, Hallie Lipinski, Abbie Royer
    • Ann Bryant
  • University of Maine Cooperative Extension
  • University of Maine School of Food and Agriculture

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