Pet
overpopulation is a problem that has persisted in the United States for decades.
Veterinarians and shelters attempt to combat this issue by advocating, or often
requiring, animals be spayed or neutered. Overpopulation is the result of
several factors including feral cats and dogs. Additionally, some pet owners
may be unwilling to spay or neuter their pets due to financial stress or
ideology. However, due to a new vaccine, this surgical process may soon become
obsolete.
Past
vaccine research relied on the immune system to generate a response and release
gonadotropin-releasing hormone (GnRH) blocking antibodies. This hormone is
required for the development of egg or sperm, by blocking this pathway
fertilization cannot successfully occur. However, since an immune response is
required to release the antibodies, the vaccine was short lived and required a
booster shot every few years. This type of vaccine would prove inefficient for
the management of feral populations who would need to be recaptured every few
years.
Biologist
Bruce Hay and his colleagues used a different approach and instead targeted
muscle cells due to their longevity. DNA is packaged into an inactive virus
shell and injected spurring muscle cells to produce anti-GnRH antibodies. This
approach creates a vaccine that is effective for 10 years, which spans the active
reproductive period of many animals. This vaccine has been shown to result in
infertility in both males and females.
Researchers
caution this vaccine is still in the early stages of development. The vaccine
has only been tested in mice. More studies and modifications must be made to
ensure the protein will be effective in other species. Additionally, research
is still being conducted to decrease the two month time lag between vaccination
and activity. This time lag exists because muscle cells take two months to
produce the protein in sufficient quantities to generate the required response.
This
vaccine may be a great alternative for pets who, due to preexisting conditions
may be at risk to be anesthetized. The procedure will be less invasive for all
pets and carries little risk of infection. Additionally, for those owners
avoiding spaying or neutering due to financial distress, the vaccine may be a
more affordable option. This novel approach has spurred further research into
blocking other molecules as well. Pet overpopulation may soon be a problem of
the past.
Link to Original Article: http://news.sciencemag.org/biology/2015/10/dna-vaccine-sterilizes-mice-could-lead-one-shot-birth-control?rss=1
This is an interesting scientific approach to a problem that definitely has an impact on modern urban society. My concern is that anti-GnRH antibodies will bind in areas where they are not supposed to and have deleterious effects on GnRH functions other than simply regarding reproduction. In "Vertebrate Endocrinology: Fundamentals and Biomedical Implications, Volume 4, Part B" Judy King and Robert Millar explain support for the belief that GnRH indeed has effects outside of the pituitary and reproduction. They explain that: 1. More than two forms of GnRH exist in most species' brains 2. GnRH molecules exist occur in extrahypothalamic tissue and outside the CNS 3. Receptors for GnRH exist in extrapituitary tissue 4. GnRH stimulates release of other pituitary hormomes 5. GnRH affects function of several extrapituitary tissues. For these reason's, they continue, it is unlikely that GNRH blockage would only have the effect of blocking reproductive ability, atleast in organisms as complex as humans.
ReplyDeleteIf their work is accurate, where and how (if at all) are rats being affected by blocking GnRH receptors? Are rats different than humans? Could pregnancy/reproductive rates play a role in effectiveness? There are many questions yet to ask, but research is moving in a great direction!
Fascinating article, which I can relate too because my family has dogs and my parents were not too big on wanting to spay ours. I had similar questions after reading this blog as Owen did above! I am wondering what other problems the deficiency of gonadotropin may cause in the body? The pituitary is obviously an important secreter of hormones in the body, so I am just questioning whether this vaccine will affect the functions of the pituitary other than the release of ganodotropin. I am also interested in how the vaccine might affect different dogs? I know this blog specifically talked about pets, but I am curious to know if the vaccine would have the same effect in a confined pet rather than a free roaming animal? Would these differences dictate what kind of inhibitors are used? Awesome blog though! Thanks for sharing.
ReplyDeleteThis is could be such an interesting solution to a very serious problem! However, it's unfortunate that the vaccine takes about 2 months to work, though. I wonder if the lag time would be even longer in larger pets, such as dogs. It may be interesting if the actual anti-GnRH antibodies could be injected directly in an effort to keep the pets protected while the long-term effects kick in.
ReplyDeleteWhile a very interesting idea and I do agree with the questions above, but I also wonder how this vaccine effects the other issues that lurk from having a pet that is not spayed or neutered. Removing the sex organs removes the hormone release from them. Neutering a dog, for example, decreases aggressiveness, wandering, testicular cancer, and the nasty habit of marking literally everything. Spaying a female carries its own benefits. A female dog after her first heat is more likely to get breast cancer and uterine infections. It also gets rid of the need to put your dog in a diaper every time she goes through menses.
ReplyDeleteSo while i can appreciate the use of this vaccine for sterilization, it doesn't cover all of the problems that are addressed by the alternative surgical solution. Overpopulation of cats and dogs is a very sad and very preventable issue in this country. Many pet owners do not like the idea of their pets getting surgery and do not spay or neuter because of it. This vaccine would at least provide protection for the pets of those particular owners.
References:
https://www.avma.org/public/PetCare/Pages/spay-neuter.aspx