Mare Infertility

Question 1

What are the uterine defense mechanisms?

Answer 1

• Anatomical Barriers
  
  • Vulva
  • Vestibulo-vaginal fold
  • Cervix
• Immunologic CLearance
  
  • Neutrophils
  • IgA and IgG
• Physical/Mechanical Clearance
  
  • Myometrial contractions
  • Cervical relaxation
  • Uterine position
  • Lymphatic drainage

Question 2

What determines if transient endometritis is cleared or develops into endometritis after uterine invasion?

Answer 2

• Normal mare “resistant”
  
  • eliminate bacterial contamination within 24-72 hrs
  • Eliminate fluid within a few hours
• “Susceptible” mare
  
  • Poor uterine defense mechanisms
  • Delayed uterine clearance
  • Poor uterine position (pendulous uterus)
  • Unable to eliminate bacteria by 96hrs
  • Usually multiparous or older mares
  • Develop persistent endometritis

Question 3

What are the different types of uterine infections?

Answer 3

• Endometritis - inflammation/infection that involves only the endometrium
• Metritis - infection that progresses deeper into the myometrium
  
  • Typically post-partum mares: dystocia or retained placenta
  • At risk of septicemia, endotoxemia, and laminitis
  • Life threatening
• Perimetritis - infection that involves the serosal surface
  
  • extension of peritonitis
• Pyometra - accumulation of purulent exudate within the uterus
  
  • not associated with endotoxemia, septicemia or systemic illness

Question 4

What is Endometritis?

Answer 4

• Main cause of infertility (failure to conceive, pregnancy loss)
• Acute/Chronic infections, post-mating induced
  
  • Bacterial, venereal or fungal infection
  • Post-breeding
  • Self-contamination perineal or poor vulvar conformation
    
    • ascending infections, urovagina, pneumovagina
  • Iatrogenic
    
    • Uterine therapies and diagnostics

Question 5

How is Bacterial Endometritis diagnosed and treated?

Answer 5

• Dx: swab and culture
• Tx:
  
  • intrauterine or systemic antibiotics
  • Restore anatomical barriers
  • +/- Remove uterine contents
    
    • uterine lavage
    • ecbolic medications - Expel fluid
      
      • Oxytocin 10-20 IU IM/IV
        
        • every 2-6hrs
        • Uterine contractions for 30-45 min
      • PGF_2a SID/BID
        
        • dinoprost or cloprostenol
        • Uterine contractions for 2-4 hrs
  • +/- Immunostimulant
    
    • SETTLE^®: stimulates production of anti-inflammatory cytokines
      
      • Mycobacterial cell wall fraction
      • Labeled for streptococcal endometritis

Question 6

How are Intrauterine Infusion

Answer 6

• 60-100 ml volume
• Daily for 3 to 5 days
• During estrus
• Recheck culture/cytology prior to breeding

Question 7

What are Biofilms? Why do they complicate Bacterial Endometritis?

Answer 7

• Extracellular polysaccharide matrix
  
  • E. coli
  • K. pneumonia
  • P. aeruginosa
  • S. zooepidemic
  • Bacteria and yeast
• Protects bacteria in microcolonies from:
  
  • Host immune system
  • Antibodies and antibiotics from reaching bacteria
• In vitro 80% of bacteria from equine uterus capable
• Require ~1000x higher antibiotic concentrations
• Biofilm Tx:
  
  • Buffered chelators: Tris-EDTA or Tricide
  • Infuse 250-500 ml Tris EDTA or Tricide on day 1
  • Uterine lavage within 24 hrs
    
    • Examine the efflux
    • If efflux is cloudy or contains mucus infuse with chelating agent again on day 2
  • Antibiotic infusion is began on day 3 following uterine irrigation
    
    • minimum of 5 days

Question 8

What is Pyometra?

Answer 8

• Intrauterine purulent exudate
• Impaired uterine clearance
• No systemic signs
• Estrous cycles
  
  • Normal
  • Shortened (acute)
  • Prolonged (chronic)
• Poor prognosis for fertility
• Treatment

Question 9

What is Post-mating induced endometritis?

Answer 9

• Inflammatory reaction mainly from spermatozoa
• Excessive fluid and inflammatory cells accumulate following breeding
• Transient endometritis is normal following insemination
  
  • Clears uterus of excessive spermatozoa, seminal plasma, and contaminates
  • Peaks at 10-12 hrs and resolved w/in 24hrs
• Failure to clear w/in 24-72hrs
  
  • May create uterine environment incompatible with embryonic life
  • Premature release of PGF_2a resulting in luteolysis

Question 10

How is Post-mating endometritis prevented/treated?

Answer 10

• Prevention:
  
  • Minimize inflammation - breed 1x per estrous cycle:
  • Ecbolic drugs: starting 4-6hrs post breeding
    
    • Oxytocin 10-20IU IM/IV q4-6hrs
    • PGF_2a
      
      • Dinoprost (5-10mg IM) or Cloprostenol (250mcg IM) SID
      • use before ovulation
  • Uterine lavage: starting 4-6 hours post breeding
    
    • Decreased uterine fluid accumulation
    • Increased pregnancy rate in mares with PMIE
• TX:
  
  • sperm transport to the oviduct is complete within 4-6 hrs
  • Physically evacuate uterine contnts
    
    • Ecbolic drugs (Oxytocin, PGF_2a)
  • Uterine Lavage
    
    • 1-2 L LRS
    • 6hrs post mating
    • can continue until 3 days post-ovulation

Question 11

What does fluid accumulation during estrus mean?

Answer 11

• Can accumulate w/out positive culture/cytology (sterile)
• Fluid alone does not signify endometritis
• May predispose mares to bacterial growth after breeding
• Defect in uterine clearance and/or uterine defense mechanisms may cause fluid accumulation
• Greater than 2cm of fluid during estrus may indicate that mare will be predisposed to post-breeding induced endometritis

Question 12

What causes venereal infertility

Answer 12

• Equine Coital Exanthema
• Pseudomonas aeruginosa
• Klebsiella pneumonia
• Taylorella equigenitalis (Contagious Equine Metritis)

Question 13

What is Equine Coital Exanthema? clinical signs?

Answer 13

• EHV-3
• Systemic illness uncommon
  
  • secondary bacterial infection
• Venereal
• Incubation 48hrs - 10days
• Clinical signs:
  
  • Unobserved
  • Vulvar discharge
  • Multiple raised nodules covered by crusty scabs on vaginal mucosa, vulva, penis, and prepuce
    
    • Shallow erosions with irregular but sharply defined margins
    • Hyperemia
  • +/- loss of libido
  • Resolve in 10-14 days leaving areas of depigmented skin
  • does not affect fertility

Question 14

How is Equine Coital Exanthema Diagnosed and treated? How could it be prevented?

Answer 14

• Dx:
  
  • Clinical signs
  • complement fixation (up to 60 days post-exposure)
  • Serum neutralization (at least 1 year post-exposure)
• Tx:
  
  • Sexual Rest
    
    • allow ulcers to heal
    • Prevent spread of disease
  • Antibiotic ointments +/- systemic
• Prevention:
  
  • Sexual rest
  • Isolation
  • Disposable equipment
  • Examine all horses prior to breeding
  • Artificial insemination

Question 15

What is Contagious Equine Metritis (CEM)?

Answer 15

• Gram negative coccobacillus
• Reportable disease
• Clinical signs:
  
  • Endometritis
  • Cervicitis
  • Vaginitis
  • Copious amounts of vulvar discharge
  • Short estrous cycles
  • Infertility
• Mares may become asymptomatic carriers

Question 16

Where are the coccobacillus that cause CEM carried on the stallion/mare?

Answer 16

• Stallion
  
  • Urethral fossa
  • Urethral orifice
  • Skin of the penis
  • Preputial folds
  • Pre-ejaculatory fluids
• Mare
  
  • Uterus
  • Cervix
  • Clitoral fossa
  • Clitoral sinus

Question 17

How is CEM diagnosed?

Answer 17

• 3 cultures (days 1, 4, and 7)
• Amies transport media
  
  • w/charcoal
  • Transported at 4C
  • Plated w/in 48hrs
• Sample from:
  
  • Mare - Clitoral fossa and sinus
  • Stallions- urethral fossa, urethral orifice, skin of the penis, preputial folds, pre-ejaculatory fluids, Test breeding

Question 18

How is CEM treated in mares?

Answer 18

• 5 days consecutive treatment
• Remove organic debris and smegma from clitoral fossa and sinus
• Cleanse the clitoral fossa and sinus with 2-4% chlorhexidine
• Pack clitoral fossa and sinuses with nitrofurazone or SSD
• Then reculture
  
  • Requires 3 negative cultures

Question 19

How is CEM treated in Stallions?

Answer 19

• 5 consecutive day treatment
• Wash erect penis and prepuce with 2-4% chlorhexidine
• Coat dried penis and urethral fossa with nitrofurazone or SSD
• Reculture the stallion
• Breeding of test mares
  
  • Mares cultured days 3,6, and 9 post breeding
  • Complement Fixation testing on days 15 and 20 post breeding