Approaches to Non-Surgical Fertility Control
"What is non-surgical sterilization for cats and dogs?"
We’re often asked this question. The answer: there is no single approach to controlling reproduction without surgery. The field is wildly diverse, complex, and (in our humble opinion!) fascinating. The brain, pituitary gland, and gonads are all vital to reproduction; this yields multiple potential approaches for temporary or permanent infertility in male and female cats and dogs.
In some cases, mammalian physiology makes it possible for a single approach to effectively suppress fertility across multiple species, dogs and cats included, and/or in both males and females. In other cases, a particular approach is possible for only one species or one sex. Read on for a brief description of several key approaches; click on each to learn more.
Immunological approaches: These approaches use a vaccine to stimulate the body’s immune system to produce antibodies to key proteins involved in reproduction.
GnRH agonists and antagonists: Gonadotropin-releasing hormone (GnRH) agonists and antagonists target this key hormone for reproduction. GnRH agonists, commonly administered by implant, are further developed than antagonists for dogs and cats.
Sex steroids: Think of “The Pill” for dogs and cats. Use of sex steroid hormones, the most common of which are progestins (synthetic progesterone), for fertility control has been explored in both species. Available in oral or injectable forms, and effective at preventing pregnancy, they must be given on an ongoing basis and carry some significant risks, particularly with extended use.
The gonads: Sometimes referred to as “chemical castration,” this involves injecting a chemical agent into a male dog or cat’s testis, epididymis, or vas deferens to cause permanent azoospermia and sterility. To date, there are no viable non-surgical options directly targeting the female ovaries which are, obviously, less accessible being inside the body.
Gene transfer and gene delivery: In this approach, a gene (DNA) is introduced into cells, usually by injection of engineered viral vectors, which carry the DNA to various organs such as the liver or muscle. The gene is then translated into a protein. Depending on the gene delivered, a variety of proteins may be expressed that can suppress animal reproduction, thus resulting in contraception. The large number of genes involved in reproduction provide numerous possible targets. This approach has the potential of producing long-term or permanent contraception in the animal because the gene, delivered by a single injection, may be expressed indefinitely.
You can also find detailed information on each of these—and other—approaches in ACC&D’s e-book, Contraception and Fertility Control in Dogs and Cats, published in 2013 and available for download at no cost.