In response to a reader request for information on degenerative testicular disease, Carol S. Bardwick (President, Canine Cryobank, Inc.) has given us some anecdotal information relative to this and related problems in the stud dog.

Recollections from 12 years working/ owning a reproductive specialty practice.

... still waiting to see a controlled study from some university in an attempt to explain the circumstances leading up to a diagnosis of degenerative testicular disease or the other frequent diagnosis of university staffs nationwide -- immunologic testicular degeneration.

One stud owner spent $2,000 at a university for infertility work-up on his four year old GSD (German Shepherd Dog). Diagnosis after all tests including testicular biopsy: immunologic testicular degeneration. Cause unknown, said the university veterinarians.

So this dog's two year old son came in to be AI'd recently. Sperm quality poor. And, when was this dog vaccinated? Just weeks ago. And, how often is this dog vaccinated? Every three months!! Just like his father was!!! Never in the $2,000 work-up at the university did anyone ask about the vaccination frequency.

Field Labrador owner calls, very upset that his field champion has poor quality sperm. History of this case and the others are chillingly similar. Because the Lab competes every weekend, mostly by flying to the trials, and once every six weeks goes into Canada, the handler's veterinarian insisted on vaccinating with DHLPP and RABIES before EVERY Health Certificate. To complicate matters, this dog was also on Heartguard.

Dandie Dinmont Terrier owner called with report of poor sperm quality. She did the usual cultures, thyroid profile, etc. She had taken the dog to her state university vet school and they found no reason for subfertility. She called the office one day still very distraught at the poor sperm quality. I happened to answer the phone.

We went over history again. Poor sperm quality coincided with start of Heartguard. Within 60 days off Heartguard, sperm was looking great. Her local veterinarian after discussing the possibility of Heartguard interfering with the healthy sperm production, suddenly remembered that when he himself had recently purchased a prize bull, the farm warned him that Ivermectin (the ingredient in Heartguard) would cause this bull's sperm count to drop!

Aussie owner called about needing a semen evaluation. While with her, the dog never missed a bitch. When she sent the dog to Texas to compete, the dog started missing bitches. In Texas, the dog was put on Heartguard. His semen evaluation right after his return was poor. But within two months after Heartguard was stopped, sperm was fine.

I could go on and on. Scientists and Merck Pharmaceutical (who manufactures Heartguard) would say these incidents are only "anecdotal." So be it. However, I am still waiting for Merck to send me any long term reproductive studies on canines on Heartguard. Then I could share the studies with my clients. Unfortunately, Merck has only sent data on rats and mice. I asked if they had ever done any studies at all on Ivermectin and reproduction in the canine. "I'll get back to you," said the Merck veterinarian in 1992.