This guideline helps to identify the sensitivity of specific bacteria and/or yeast infections that infiltrate the internal and external reproductive tract of both stallion and mares. From this initial information, a window of procedural rational will allow the categorization of a stallions or mare's potential for reproductive competence. When assessing the reproductive competency of a mare or stallion, a complete examination should take place with the following key points.
For mares: A uterine biopsy and culture with sensitivities & cytology; A complete endocrine evaluation for multiple year barren mares should be considered.
For stallions: A culture of the urethra before and after ejaculation and a semen culture where by evaluation for a potential growth at 24, 36, 48 & 72 hours should be conducted.

Commonly Used Intrauterine Drugs
Guidelines for Specific Use & Administration in Large Volume Lavages

Antibiotics for Gram Positive Bacteria
Penicillin (Na+ or K+ Salt K-Penn)
5 million units
Very effective for streptococci; economical and commonly used

Ampicillin
1-3 g
Use at high dilutions because it can be irritating; NA+ salt leaves precipitate on endometrium that remains in uterus for prolonged period

Carbenicillin
2-5 g
Reserved for persistent Pseudomonas (synergistic efficacy with amino-glycosides); usually given on alternate days with amino-glycosides; slightly irritating

Gentamicin Sulfate
500-1000 mg
Highly effective; generally nonirritating when mixed with an equal volume of NaHCO3 and diluted in saline

Amikacin Sulfate
2 g
Use for Pseudomonas, Klebsiella, and persistent gram-negative organisms

Kanamycin Sulfate
1 g
Toxic to spermatozoa; do not use close to breeding

Polymyxin B
1 million units
Gram-negative infections, particularly Pseudomonas

Neomycin Sulfate
3-4 g
Use for sensitive E. Coli; can be irritating; post breeding use of oral preparations containing neomycin mixed with other antimicrobials has lowered pregnancy rates in mares

Nitrofurazones
50-60 ml
Highly questionable effectiveness

Antibiotics for Gram Positive & Negative Bacteria

Cephazolin Sodium
1 g
First-generation cephalosporin; has been used empirically once daily intramuscularly for 2-3 weeks; broad spectrum effectiveness against Gram-positive and Gram-negative bacteria

Ticarcillin
1-3 g
Use for Pseudomonas; do not use for Klebsiella

Naxcel (Ceftiofur Sodium)
1 g
Third-generation cephalosporin; has been used empirically once daily either intramuscularly or by intrauterine infusion; broad-spectrum effectiveness against Gram-positive and Gram-negative bacteria

Povidone-Iodine
(1%-4% of stock solution of Betadine, which is 0.5% Povidone iodine)
1 liter (lavage solution)
If solutions are too concentrated (e.g., >5% Betadine v/v), severe endometritis results and/or neutrophil function is impaired; in vitro bactericidal activity is maintained at concentrations as low as 0.01%-0.005%; indicated for lavage of uteri with nonspecific inflammation or fungal/yeast infections; should not be left in uterus

Yeast Specific Drugs

Nystatin
500,000 units
Primarily for yeast (e.g., Candida albicans) in the growing phase; dilute in 100 t0 250 ml sterile water--makes an insoluble suspension that must be vigorously mixed immediately prior to infusion

Amphotericin B
200 mg
For infections with Aspergillus, Candida, Mucor, or Histoplasma; dilute in 100 to 250 ml sterile water--makes a relatively insoluble suspension

Clotrimazole
700 mg
For yeast infections (Candida spp.); available as cream, tablets, or suppositories; preferable treatment is with tablets crushed and mixed with 40 ml sterile water; generally infused after uterine lavage

Miconazole
200 mg
Most efficacious for yeast infections (Candida spp.), but has been used by some practitioners for resistant fungal infections in mares by infusing once daily for up to 10 days; dilute in 40-6- ml sterile saline prior to infusion

Drugs for Aggressive Reproductive Management

Dimethylsulfoxide (DMSO)
(5% of stock solution)
50-100 ml
Used as penetrating agent to carry drugs; effectiveness and safety unknown

EDTA-TRIS (1.2 g NaEDTA + 6.05 g TRIS/L of H20, titrated to pH 8.0 with glacial acetic acid)
250 ml, then infuse antibiotic 3 hours later
EDTA theoretically binds Ca++ in bacterial cell walls, making cell wall permeable to antibiotic and thus more susceptible; use confined to persistent Pseudomonas infections

Commonly Used Drugs In Semen Extenders

Gram Positive Activity

Penicillin (Na+ or K+ Salt) (K-Penn) +
1 million units per 100ml of final semen extender solution.
Very effective for streptococci; economical and commonly used

Gram Negative Activity

Amikacin Sulfate -
1 mg per 1ml of semen extender solution.
Use for Pseudomonas, Klebsiella, and persistent gram-negative organisms

Gentamicin Sulfate -
1 mg per 1ml of semen extender solution.
Highly effective; generally nonirritating when mixed with an equal volume of NaHCO3 and diluted in saline

Polymyxin B -
1 million units per 100ml of final semen extender solution.
Gram-negative infections, particularly Pseudomonas

Gram Positive or Negative Activity

Ticarcillin + -
1 mg per 1ml of semen extender solution.
Use for Pseudomonas; do not use for Klebsiella

Naxcel (Ceftiofur Sodium) + -
1 mg per 1ml of extender solution
Third-generation cephalosporin; has been used empirically once daily either intramuscularly or by intrauterine infusion; broad-spectrum effectiveness against Gram-positive and Gram-negative bacteria

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