FDA Approves First Shot to Neuter Puppies

Published in the Home News Tribune 6/09/03
THE ASSOCIATED PRESS

Veterinarians now can offer an alternative to surgery to neuter
puppies. Called Neutersol, it's a shot administered directly into the
testicles of puppies at the right age for neutering.

The ingredients -
- the amino acid l-arginine and a zinc salt -- cause the testicles
and prostate to atrophy. The alternative, surgically removing the
testicles, guarantees sterility. In a study of 224 dogs, Neutersol
did almost as well: Semen analysis showed only one sterilization
failure, said Dr. Melanie Burson of the Food and Drug Administration.
The FDA approved Neutersol in March, but did not announce the
approval until Monday.

A type of chemical castration already is available for humans. Sex
offenders often are sentenced to regular injections of hormones that
deplete testosterone. But that's not permanent sterilization.
The new method for dogs is permanent, but some testosterone production
continues because it's not hormonally driven, Burson said. So unlike
surgical castration, Neutersol may not eliminate unwanted male
behaviors such as roaming, marking and aggression, the FDA warned.
Pet overpopulation is a serious problem, and scientists have
struggled to find ways to make animals infertile. Some were dangerous
either for the animal or for the veterinarian administering them,
said Bruce Addison, founder of Addison Biological Laboratory of
Columbia, Mo., which is selling Neutersol.

For some reason, Neutersol ingredients are toxic to cells when
injected directly into the testicles but not other parts of the body,
Addison said.

It is crucial for vets to administer the shot properly, and for
owners to care for the puppy during the following week to avoid
ulceration and infection of the injection site, the FDA said.
Scientists now are studying whether Neutersol can safely sterilize
older dogs and cats, Addison said.

© copyright 2003 The Associated Press
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