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Science Overview

Dear Friends of 600,

It is my honor to present our Spay and Neuter Cookie Overview.

As you know, our science-centered mission is to significantly reduce animal suffering by developing safe, non profit, permanent one-dose birth control food for stray dogs and cats.

Our approach is to modify known ingredients so that they will safely sterilize a stray without surgery.  

The first birth control food we are developing are the

Spay and Neuter Cookies.

They are being designed to be species- and gender-specific, and we expect the first Cookie that will be completed will be for female dogs.

Our Pilot Pups

When we rescue a stray, in addition to caring for her or him, we also feed her or him a single trial Cookie.

Once a rescued stray has eaten a single trial Cookie, she or he becomes an official Pilot Pup.

We also cover the associated costs such as veterinary care, food, housing, transportation, adoption -- and we add a hefty dose of love and affection.

Trial Cookies 

Each trial Cookie contains a combination of key ingredients and trial formulations -- often as many as 15 or more variables go into a single Cookie, such as the varying temperatures at which they are prepared and the length of time they are heated, all of which we are evaluating.

At this stage of development, each trial formulation (trial Cookie) must be made by one or more scientists and made by hand one at a time.

The work is labor-intensive and each trial formulation is unique and can cost thousands of dollars and take months to prepare -- and many formulations need to be evaluated.

Once the final formulation is completed, our goal is to be able to produce it in bulk for under $5 per Cookie.

In our work, the welfare of the Pilot Pup comes first, before the science. We take precautions and go out of our way to ensure that each trial Cookie is as safe as possible, based on using ingredients and amounts that we already know to be safe.

For the safety of the Pilot Pup, to study variations in formulas, we only increase key ingredients by very small, controlled amounts,  one tiny step at a time.

This is a significant factor in why it is taking so long to perfect the formulas.

In contrast, a for-profit drug company would not typically follow our one tiny step at a time approach; instead they would increase the dose as high as possible and as fast as possible, to cut costs.

Some of us humans at 600 have eaten trial Cookies ourselves, myself included.

Thus far there have been no negative side effects for animals or people. We suspect a key reason for the lack of negative side effects is that the Cookie is designed as a rare “only one dose over a lifetime” product, unlike traditional birth control products that are ingested daily.

Evidence also shows, thus far, that eating multiple doses (of the ingredients of the Cookies) does not harm the animal.   

After the Pilot Pup eats the single trial Cookie, the Pup usually stays at the veterinary clinic for a few days to ensure that he or she is in good health.


As soon as they get the green light from the veterinarian, they go home to their foster or permanent home.

If a home is not readily available, the Pup stays at the veterinary clinic or in a foster home, or in an animal adoption center run by compassionate people who provide daily care, affection, and exercise, until a permanent home is found.

Dog Spay and Neuter - Histology whole ovary analysis

An entire ovary in the process of being analyzed. 

Cat Spay and Neuter - Histology follicle evaluation

A closer view of the same ovary; follicle evaluation in progress.

Histology follicle evaluation magnified Alex Pacheco 600 Million Dogs

Greater magnification, with follicle evaluation in progress.

Dog overpopulation - Primary follicle
Cat overpopulation - Primary follicle
Animal overpopulation - Primary follicle

Approximately one month after eating the trial Cookie, the Pilot Pup comes back to the veterinary clinic, the veterinarian performs a spay or neuter surgery and the Pup goes home again.

In a standard spay or neuter surgery, the veterinarian discards any tissue that is removed, such as the ovaries or testes.

In our case, the veterinarians keep these now-treated tissues, and we provide them to other specialists to histologically process them physically, chemically and digitally for microscopic examination.

Once the slides are digitized, we have them microscopically examined by other specialists.

This examination is a painstaking process, and it allows us to determine if the Pilot Pup is sterile as a result of eating the single trial Cookie.

This in turn allows us to learn if the trial formulation worked.

How do we know if the Cookie worked?

It’s a long and important answer.

These are the basics of what we refer to as the count, our nickname for the percentage of various types of ovarian reproductive follicles that are impaired.


The more follicles that are impaired (the higher the count) the better, and the closer the dog is to being infertile. 

For example, a high count occurs naturally through aging in humans and dogs  -- which is why elderly humans and dogs naturally become infertile.

Our scientists review, analyze and quantify these follicles under a microscope, and one of the things we’re trying to do is cause as many of these follicles as possible to become impaired --without harming the animal, of course.

Our scientists then provide us with a report on each tissue, including the percentage of impaired follicles.

600 Million Dog Cookie - Histology
600 Million Dog Cookie - Histology
600 Million Cat Cookie - Histology

A count of 20% means 20% of a certain type of follicle were found to be impaired. 

Again, the higher the count the better, and the closer the dog is to being infertile.

Conducting accurate counts is not easy, and we send the same digital slides to various specialists in order to secure second and third opinions.

Thus far, three of our best cumulative counts (the counts for all follicle types found to be impaired, combined) have been 41%, 45% and 69%.

In short, these are surprisingly high numbers and good news for the animals.

Some additional good news:

Three of our best individual counts (the counts for individual types of follicles) are higher than the cumulative counts.

The best news is that each of these results have come from their own single trial Cookie formulation -- produced on a minuscule budget, with scientists working on our behalf in their spare time.


At this point, our budget is around $270,000.

600 Million Spay and Neuter Cookie - Histology
600 Million Spay and Neuter Cookie - Histology

What is the magic number that produces infertility?

According to the scientific community, the answer is unknown.

At this time the answer is not clear when it comes to dogs, cats, or humans.

What is known is that in humans, for example, it is common for an adult female in her sixties to be infertile yet still have a considerable number of normal follicles.

This is good news for dogs and cats, because it means that if a human female can be sterile even though not all of her follicles are impaired (she has less than a 100% count), the same can be true for dogs and cats, who have reproductive systems very similar to humans.

Our ability, going forward, to reliably produce a high yet less than 100% count should be much easier than producing a 100% count -- all of which is good for the animals.

When will we discover the winning formula

and how much will it cost?

As with most scientific endeavors, no one can answer this question with certainty -- just as no one can predict the future with certainty.

A team of scientists formulated projections for the time and cost that would be required to complete the work, including the studies needed to submit the data to the FDA and initiate the FDA approval process so that the product can be used in the U.S.

They reached the following conclusion:

With a budget of $3 million per year for 3 years, the Cookie could be developed within those 3 years, including the studies needed to initiate the FDA approval process.

These funds would go toward hiring scientists, allowing them to devote themselves full-time to the project.

As you know, we are not waiting for the $3 million.

Our plan is to continue our research and development to find the winning formula -- without applying for FDA approval at this time.

Instead, our work is being performed at a grassroots level:

Scientists are retained individually and paid on a limited hourly basis, and much is done outside of the U.S.

Instead of waiting for FDA-level funding, we intend to continue at the grassroots level, find the winning formula -- and put it to work in field trials in parts of the world where the need is the greatest and where the suffering is the most severe.

Despite the obstacles, we are pushing forward to make the Spay and Neuter Cookie a reality.

At this time, we are actively pursuing opportunities to carry out the work humanely, cost-effectively, and with the best scientists and technology available in the U.S.

In the meantime, I cannot thank you enough for your support.

600 Million Spay and Neuter Cookie - Histology
600 Million Spay and Neuter Cookie - Histology
600 Million Spay and Neuter Cookie - Histology
600 Million Spay and Neuter Cookie - Histology
600 Million Spay and Neuter Cookie - Histology
Alex Pacheco 600 Million Dogs on Porch.j
Alex Pacheco

600 Million Stray Dogs Need You
Animal Rights Hall of Fame 
Adopt A Pet 
PETA Co-Founder 
Chairman (1980-2000)
Sea Shepherd 
Crew Member of the Year
Peace Abbey 
Courage of Conscience Award

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