Practical Matters: What's the significance of Mycoplasma species in the urogenital tract?


Practical Matters: What's the significance of Mycoplasma species in the urogenital tract?

Dec 01, 2008

Margaret V. Root Kustritz, DVM, PhD, DACT
Mycoplasma species are bacteria that lack cell walls and are part of the normal flora in dogs and many other species on mucosal surfaces, including the vagina and distal urethra. Mycoplasma species are difficult to culture, so many laboratories are hesitant to provide information about the quantity grown from vaginal swabs or semen.

While there is some evidence of Mycoplasma species infection associated with vaginitis and pregnancy loss in bitches and poor semen quality in male dogs, studies have demonstrated that Mycoplasma species are as likely to be cultured in samples from healthy animals as they are to be cultured in samples from animals with reproductive tract disease.1,2

It also has been demonstrated that indiscriminate use of antibiotics in bitches may increase the number of Mycoplasma species organisms present in the vagina.3 Mycoplasma species are ubiquitous in the environment, so treated dogs will reestablish Mycoplasma species on mucosal surfaces with time. Thus, treating all dogs in a kennel or household from which a dog has had a positive Mycoplasma species culture result is inappropriate.

Culture for Mycoplasma species may be considered when there are clinical signs or changes in clinical pathology suggestive of infection and when regular aerobic and anaerobic bacterial cultures are negative. Treatment must always be undertaken with the understanding that there is no definitive way to determine whether Mycoplasma species cultures are pathogenic in that animal at that time. Most laboratories will not provide susceptibility testing to guide antibiotic therapy; tetracycline and fluoroquinolones have been shown to be effective. 4

Margaret V. Root Kustritz, DVM, PhD, DACT
Department of Veterinary Clinical Sciences
College of Veterinary Medicine
University of Minnesota
St. Paul, MN 55108


1. Doig PA, Ruhnke HL, Bosu WT. The genital Mycoplasma and Ureaplasma flora of healthy and diseased dogs. Can J Comp Med 1981;45(3):233-238.

2. Davidson AP. Frustrating case presentations in canine theriogenology. Vet Clin North Am Small Anim Pract 2001;31(2):411-420.

3. Strom B, Linde-Forsberg C. Effects of ampicillin and trimethoprim-sulfamethoxazole on the vaginal bacterial flora of bitches. Am J Vet Res 1993;54(6):891-896.

4. Greene CE. Mycoplasmal, ureaplasmal and L-form infections. In: Infectious diseases of the dog and cat. Philadelphia, Pa: WB Saunders, 1998;174-178.