The Importance of Spay and Neuter on Shelter Populations

One of the best ways to stop unnecessary euthanasia of healthy pets in animal shelters is to reduce the number of animals entering our shelters.

Pet overpopulation is a huge issue in the US, with 6,550,000 dogs and cats entering shelters in 2023. 850,000 of those animals didn't make it out alive.

Of course, this is a multi-faceted issue without one easy solution, but there is a step that we can take to reduce both intake and euthanasia numbers: widespread spay and neuter.

What is spay and neuter?

Spay and neuter are surgical procedures that sterilize an animal, meaning that they are unable to reproduce. Other common terms for spay and neuter include sterilized, fixed, and altered.

When a female is spayed, she typically undergoes an Ovariohysterectomy, removal of the ovaries, fallopian tubes, and uterus. This completely eliminates her ability to get pregnant.

When a male is neutered, he undergoes an Orchiectomy, removal of the testicles. This completely eliminates his ability to get a female pregnant.

These routine surgeries are performed quickly, with pets typically returning home the same or next day. Recovery time lasts about 10-14 days to allow incisions to properly heal.

Unplanned litters are a major contribution to overpopulation

It doesn't take much for an unplanned litter to happen! Many people are surprised when their dog or cat ends up pregnant after a single interaction with another unaltered pet. This is likely due to widespread misinformation or lack of understanding about when and how a dog or cat can get pregnant.

Some people are lucky enough to find homes for all of the puppies or kittens with friends, family, or neighbors, but an overwhelming number will find their way into a shelter, either shortly after leaving mom or as adolescents. 

Many puppies and kittens are also born to stray animals. This is an incredibly difficult and often fatal experience for many mothers and babies, especially in areas with extreme heat or cold, a lack of accessible food or shelter, or a prevalence of highly contagious diseases like Parvo, Distemper, or Feline Leukemia.

How many puppies or kittens can a mother have?

Female cats can get pregnant as early as six months old, delivering up to four litters per year. Most cats will have 4-6 kittens per litter, but litters can reach up to a dozen kittens each. 

Female dogs will experience their first heat cycle anywhere from 6-24 months, depending on their breed (smaller breeds tend to be earlier while XL breeds may reach 18-24 months before their first heat cycle). Most dogs will have around 5-6 puppies per litter, but some litters can reach 14-16 puppies.

Having a litter while the mother is still under a year old is quite dangerous for both the mother and babies. Many young cats and dogs are not prepared to properly care for babies and may abandon their litter; this is true of pets who are ill or living in poor conditions, too.

The shelter is no place for moms or babies

No matter their origin, owner surrendered or found as strays, the shelter is a dangerous place for new moms and their babies. Moms and babies are more susceptible to disease than healthy adult pets, and germs spread quickly even in the best of shelters.

Shelters also tend to be noisy and chaotic, which is particularly stressful for moms and babies. Extra stress can result in a mom displaying aggressive behavior towards humans and neglecting, or even injuring, her babies. Babies who experience excessive stress in their first three months of life are also more likely to develop lifelong anxiety.

Of course, there are situations in which entering a shelter is the best option for mom and babies; for example, it's a better option than freezing to death on the streets. However, great effort should be taken to move mom and babies out of the shelter and into a home environment as quickly as possible. This typically requires experienced foster homes, which can be difficult to find. 

Sadly, moms and babies are not excluded from euthanasia in many high-intake shelters. Because it is so dangerous to house them in the shelter, among other factors, like often taking up more space than the average pet, shelters who are unable to quickly move moms and babies out of the shelter may opt to euthanize them instead. This may be more likely in cases of moms and babies that are already ill, shelters that have recently experienced an outbreak of a highly contagious disease, moms who are displaying aggressive or neglectful behaviors, or very young puppies/kittens who come in without a mom and require bottle feeding without those resources being available.

Which pets should be sterilized, and when?

Opinions on the best practices for sterilization vary, but when we look at the "big picture," with hundreds of thousands of healthy, behaviorally sound pets dying in our shelters every single year, it's clear that we need to take precautions to prevent unplanned and irresponsibly planned litters.

Unless a pet has undergone thorough genetic and behavioral testing to ensure that they are a prime candidate for breeding and their human is prepared for the costs of properly caring for a mom and litter, are knowledgeable about and prepared to provide a safe environment that allows them to properly socialize babies, and are prepared to vet potential homes and provide support at any point in the puppies' lives, from an overpopulation perspective, it is typically best for pets to be spayed.

When it comes to cats, any cat that is allowed to go outside should be sterilized to avoid an unplanned pregnancy. This includes male cats, as they are quite good at finding intact females while out on adventures. Because there is almost always a non-zero risk of an indoor-only cat accidentally slipping out a door at some point in their life, spay or neuter is a good precaution for indoor cats, too.

Most dogs will have unsupervised time in the yard or spend time out in public where they may run into other dogs. Most unaltered males are quite persistent when it comes to finding intact females - all too often, they will climb, jump over, or dig under fences to get to an unsupervised female. One interaction at a dog park, dog beach, or other public area where dogs are allowed can result in a pregnancy. For this reason, sterilization is a good idea.

The American Veterinary Medical Association recommends that owned cats are sterilized by 5 months old to avoid an accidental litter. Because a dog's heat cycle will vary based on size and breed, a vet's recommendation for owned dogs may vary.

Most shelters and rescues opt for pediatric sterilization; both cats and dogs can be spayed or neutered as young as 8 weeks old as long as they meet weight and health standards. While this pediatric sterilization isn't always recommended for owned pets, from an overpopulation perspective, ensuring that all pets are sterilized before leaving the shelter is the best option.

Individual benefits of sterilization

When it comes to each individual dog and cat, there are proven benefits of sterilization.

Sterilization may reduce mating-related behaviors for many pets, which are often considered problematic by humans. This can include males roaming to find a mate (especially in dogs); marking or urinating outside of the litterbox; and aggression.

Sterilization can also have health benefits for individual pets. Sterilization is strongly associated with longer lifespans; eliminates the chance of potentially fatal infections like Pyometra; and reduces or eliminates the chance of mammary and prostate cancers.

Potential risks of sterilization

Like all surgical procedures, there are short term risks to sterilization in relation to the use of anesthesia and complications with the surgery itself. Fortunately, these risks are quite low, especially for healthy pets.

There is evidence to support some longterm health risks related to sterilization. Hormonal changes are linked to obesity in some pets and may affect the growth and development of joints and ligaments in dogs, though the risk seems to vary between dogs of different breeds and sizes.

Sterilization may also increase the risk of urinary incontinence in females and some cancers. However, more research is needed to understand how things like age at sterilization, breed, and sex affect these risks.

It is possible that non-surgical sterilization may reduce these risks, however more research is needed, and non-surgical methods are not yet easily accessible to most pet owners.

Barriers to sterilization

At the time of this article, the US is facing a nationwide vet shortage, which makes routine care more difficult to obtain. This affects the ability of both shelters and individual pet owners to access sterilization procedures in a timely manner.

Shelter barriers

Sterilization prior to adoption has become the standard for most rescues and shelters. Unfortunately, the vet shortage is making it increasingly difficult for many shelters to keep up.

While some shelters have veterinarians on staff, many smaller shelters and most foster-based rescues do not. Scheduling sterilization surgeries with a third party can be time consuming, involve long waitlists, and become quite expensive, even when they are offered a rescue discount. Some shelters may also struggle to schedule transport of animals to and from sterilization clinics.

Some shelters are forced to make a choice between letting unsterilized pets go out into the world with sterilization contracts (which can be extremely difficult to enforce) and having adoptable animals sit in care for extended periods of time, which both reduces space for incoming animals and potentially increases euthanasia rates.

Community barriers

The vet staff shortage impacts owned pets, too. Even if someone wants to spay their pet, increased prices, weeks or months long waitlists, and "vet deserts" - marginalized areas in which there are few or no veterinarians - can make it extremely difficult to do so in a timely manner. 

Some pet owners also have concerns about changes in behavior, health, or personality after sterilization. While some of these concerns are valid, as listed above, many are misguided (no, a neutered dog is not going to feel like "less of a man"). 

Increasing accessibility to spay and neuter

To increase sterilization numbers in our communities to an extent that it has a positive impact on shelter intake and euthanasia, it is imperative that there is an increase in accessibility, especially in marginalized communities.

Because cost is a huge factor for many people, offering no- and low-cost sterilization clinics for owned pets can have a positive impact. Clinics that are able to offer transportation for pets are extremely beneficial to people who depend on public transportation or face a lack of mobility.

In 'vet deserts' that have little access to vet care, pop-up clinics, mobile clinics, and voucher programs through shelters are often necessary. Longterm initiatives that provide regular opportunities to the community have the largest impact on longterm population control.

One piece of the puzzle

Unplanned litters are just one of many factors affecting shelter populations. While widespread spay and neuter could have a large impact, it's important to remember that it is only one piece of the puzzle.

Increasing adoption rates by removing barriers to adoption and increasing owner retention through outreach are also incredibly important pieces of the puzzle. All of these factors are complicated, multi-faceted issues that require cooperation and communication between the animal welfare community and the general community at large.


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