Discover the groundbreaking study shedding light on male fertility issues in the breed, potentially benefiting other breeds as well. Read more to uncover the findings.
The Importance of Proper Semen Storage for AI Breeding
Artificial insemination (AI) provides breeders with the ability to breed dogs that may not be feasible due to factors like geographical location or behavior incompatibilities. A recent study analyzed the impact of antibiotics in commercial semen extenders on bacterial growth in semen samples, aiming to determine if they can effectively increase the shelf life of semen while inhibiting bacterial growth.
“Breeders are not shipping females for natural breeding as much today and thus are turning more to AI,” says Ginny Altman, vice president of the American German Shepherd Dog Charitable Foundation. “Since semen collection introduces bacteria into the semen sample from normal bacterial flora, we wanted to learn whether the antibiotics used in extenders control the growth of bacteria.”
Carla Barstow, DVM, and Margaret Root Kustritz, DVM, PhD, DACT, professor of small animal reproduction at the University of Minnesota College of Veterinary Medicine, led a study funded by the AKC Canine Health Foundation and supported by the American German Shepherd Dog Charitable Foundation1. The study involved 14 male dogs from members of all-breed clubs in the Minneapolis area. This included six Samoyeds, six Malamutes, one English Springer Spaniel, and one Labrador Retriever, ranging from the age of 2 to 9.
“We hypothesized that the growth of aerobic, anaerobic and Mycoplasma bacteria would be controlled in semen extended with commercial canine extenders when stored at refrigerator or room temperatures for up to 48 hours,” Barstow says.
“Our study was intended to mimic what can happen in the real world. It is important for the receiving veterinarian who will do the AI procedure and the brood bitch owner to know that the semen product they are using is safe. In reality, manufacturers include antibiotics in extenders to prolong shelf life, not inhibit bacterial growth.”
Commercial semen extenders play a crucial role in the preservation and transportation of chilled and frozen semen. These liquid media provide essential nutrients and a buffering capacity to support the spermatozoa, helping to maintain their viability and fertility during the storing and shipping process. 2
Within 24 hours of shipping the chilled semen, it must be inseminated in a female dog to retain viability and reduce the risk of disease. Apart from the normal bacterial flora present in a male dog's urethra, semen can become infected through the introduction of urine from the urethra or organisms shed from prostatic or testicular fluid due to systemic infection.
To prevent disease transmission through AI, the addition of antibiotics to semen is necessary. The study examined two commonly used commercial canine extenders utilized by theriogenologists, or reproduction specialists. One extender contained multiple antibiotics, while the other contained a single antibiotic.
“Semen shipments may have been sitting on a hot truck all day with melted ice packs,” Barstow says. “Worse yet, they may have been left in an uncontrolled environment in which you have no idea whether the box was opened or whether the ice packs were left in place.”
In the study, each semen sample was divided into 11 separate samples. Three of these samples, known as neat samples, did not have any extender added and were tested for anaerobic, aerobic, and Mycoplasma bacteria. The remaining semen samples were divided into two groups, with each group receiving a different extender product. These extender groups were then stored at either room temperature (20 degrees Celsius) or refrigeration temperature (5 degrees Celsius). The samples were tested for aerobic and Mycoplasma bacteria at the time of collection, as well as at 24 hours and 48 hours after storage.
“We noted an expected motility loss in the first 24 hours,” says Barstow. “We also found that the motility of spermatozoa was not affected by the presence of bacteria, thus motility is not a measure to determine whether a sample contains bacteria.”
Related to bacterial growth, 35 percent of dogs had significant growth of bacteria in their semen, which is in accord with information from the literature, Barstow says. Bacterial growth was controlled in samples that were held at refrigeration temperature, but not in all the samples that were held at room temperature.
“Importantly, there was no significant growth in any refrigerated sample, which is the protocol for shipping chilled semen samples,” she says. “The question was whether extenders work as we thought they did, and yes, we showed they do.”
1 Barstow C, Root Kustritz MV. Effects of Antibacterial Agents in Semen Extender on Bacterial Growth in Extended Canine Semen Held at 5°C or 20°C for Up to 48 Hours. Clin Therio J. 2014; 6:231-237.
2 Root Kustritz MV. The Dog Breeder’s Guide to Successful Breeding and Health Management.
St. Louis: Saunders Elsevier. 2006.
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