Does Spay/Neuter Save North Carolina Money? The Front-End vs Back-End Dollar
In NC's state program, 2025 surgeries averaged $111 in eligible cost and the state paid about $42. The median reporting shelter spent $381 per animal handled.
Counties across North Carolina already pay for unwanted dogs and cats. A large part of the question is which end of the problem the money goes to. It can go to the front end, a spay or neuter surgery that averaged about $111 in eligible cost under the state program in 2025 (the state itself paid about $42 of that). Or it can go to the back end, a shelter that has to feed, house, treat and, too often, euthanize animals that surgery might have prevented.
This guide puts North Carolina's own 2025 numbers side by side: what the state's Spay/Neuter Program actually spent per surgery, what reporting shelters spent per animal, and what the research says about how often one surgery keeps an animal out of a shelter.
TL;DR: In 2025, North Carolina's Spay/Neuter Program surgeries averaged about $111 in eligible cost (the state paid about $42), while reporting shelters spent a median of $381 per animal handled (total spending divided by animals, so it includes buildings and staff). On those averages, a surgery breaks even if about 1 in 3.4 prevents one shelter intake. A California cat study modeled about 1 in 3.1 over roughly a decade (our calculation from its figures), so a similar rate here would roughly break even. Yet the state funded about half as many surgeries in 2025 as in 2014 and paid about 37 cents per dollar counties requested: sign the petition.
The Short Answer: $111 Average Eligible Cost vs $381 Median Shelter Cost
North Carolina runs a statewide Spay/Neuter Program through the Department of Agriculture and Consumer Services. It does not pay veterinarians or pet owners directly. It reimburses cities and counties for the direct surgical costs of sterilizing pets owned by low-income residents: anesthesia, medication and veterinary services, and nothing for buildings or administration. To qualify, an owner must be on a state public assistance program or have household income below 100 percent of the federal poverty guidelines. Local programs offer the surgeries at reduced cost; any charge to the owner is set locally, not by the state.
In calendar year 2025 the program covered 5,938 procedures. Counties documented $659,626.15 in eligible costs for them, which works out to an average of about $111 per surgery (our calculation). The state actually paid $250,954.08, or about $42 per surgery. Counties and their partners covered the rest.
Now the back end. Under G.S. 19A-65, every county or city animal shelter must file an annual report that includes its total operating expenses and its cost per animal handled. So must every shelter operated under contract with a county or city or otherwise receiving state or local funding. The state re-issued the 2025 report on October 12, 2026, though the department's reports page still labels the file "As of 7.27.26". In it, 59 facilities reported $67,066,981 in operating expenses. The 58 facilities that reported a cost per animal had a median of $381. Half of them fell between $254 and $599.
The chart below puts all three figures on one scale.
The gap is wide, but it is not yet a savings figure. A surgery only saves shelter money if it prevents an animal from coming in, and the $381 is not what a shelter saves when one fewer animal arrives. The next two sections take those points one at a time.
What the $381 Is, and What It Is Not
G.S. 19A-65 asks for "the total operating expenses of the shelter and the cost per animal handled." The state's reporting form asks for "Cost per Animal Served" and gives no formula. So each shelter calculates its own figure, most likely as total yearly spending divided by the animals it handled (neither the statute nor the form defines it). That partly explains why the reported values run from $30 at a small town facility (Town of Sunset Beach) to $1,600 at one humane society (the table below shows the full spread). It is also why we use the median rather than the average: the median is the typical shelter's own number and is not dragged around by a few unusual reporters.
Three limits matter for anyone using this figure in a budget debate.
It is an average, not a marginal cost. Much of a shelter's budget is fixed. The building, the base staff, the trucks and the field calls do not disappear when intake drops by one animal. The accurate phrasing is "the average shelter spends about $381 per animal it handles," never "it costs $381 to take in one more animal." What a shelter truly saves when intake falls is smaller than the average, and no North Carolina source has measured it.
| Reported 2025 cost per animal handled | Amount |
|---|---|
| Lowest reported: a small town facility (Town of Sunset Beach) | $30 |
| 25th percentile | $254 |
| Median | $381 |
| Average (mean) of facility figures | $464 |
| 75th percentile | $599 |
| Highest reported (a humane society) | $1,600 |
It covers reporting shelters only. Thirty-four of the state's 100 counties do not appear in the 2025 file, including Wake and Forsyth. Some absent counties are served by a regional shelter that files under a neighboring county, so a missing county does not always mean a missing shelter. Statewide totals describe reporting shelters, not every shelter in North Carolina. Our county-by-county shelter report, linked below, lists which counties are missing and what each reporting county spent.
It is not the whole public cost. A shelter's operating expenses may not capture work that falls to other county departments, such as public health follow-up on bites and rabies exposures. Those costs are real, and we cover them in our guide to the public health cost of pet overpopulation, but they are not in the $381 and we do not add them here.
None of these limits makes the comparison useless. They make it a comparison of averages, a common way to compare program costs. They also explain why the right question is not "how much does each surgery save?" but "how often does a surgery need to work for the money to come back?"
How Many Surgeries Have to Work? The Break-Even Math
Flip the question around. If a program surgery's average eligible cost is about $111 and the median shelter spends about $381 per animal, then on average cost a surgery breaks even if it prevents about 0.29 shelter intakes. Put another way: if about 1 in every 3.4 program surgeries keeps one animal out of a shelter, the program pays for itself on average shelter cost (our calculation, $111 divided by $381). Counted only against the roughly $42 the state actually paid per surgery, the bar is much lower: about 1 in 9. Counties and their partners pay the rest of the $111, and because shelters are run or funded largely by counties and cities, that is also where most shelter savings would land.
The two sides are not measured the same way. The $111 is the direct surgical cost the state judged eligible after its per-procedure caps: anesthesia, medication and veterinary services. It includes no county administrative or capital costs (the law excludes both) and nothing above the caps. The reimbursement summary does not show whether owner copays are netted out. The $381 is fully loaded, covering buildings, staff and everything else in a shelter's budget. Counties requested about $115 per surgery on average ($682,056 divided by 5,938, our calculation). That moves break-even to about 1 in 3.3 (our calculation), and even the requested figure leaves out county administration.
| Figure, 2025 | Amount | What it covers |
|---|---|---|
| State share paid per program surgery (average) | $42 | What the state actually reimbursed |
| Eligible cost per program surgery (average) | $111 | Direct surgical cost after the state's caps; no county administration or capital costs |
| Requested cost per program surgery (average) | $115 | What counties claimed before the caps; still no county administration |
| Shelter spending per animal handled (median) | $381 | Fully loaded: buildings, staff and all other operating costs |
Is 1 in 3.4 realistic? The best evidence we found comes from Santa Clara County, California, where a peer-reviewed study by Kass, Johnson and Weng (2013) looked at a cat sterilization voucher program. Vouchers paid for 20,419 cat surgeries from 1994 to 2001 and another 6,231 from 2001 to 2003, about 26,650 in all. The authors built a model to estimate "the number of additional cats that would have been born and taken into the shelters between 1994 and 2005 had the spay/neuter program never been implemented." Using assumed litter sizes, litters per year and kitten survival, it projected that the voucher cats would have produced about 312,000 kittens over that period and that about 8,600 more cats would have entered shelters in the county. That works out to about 0.32 avoided intakes per surgery, or roughly 1 in 3.1 (our calculation from the paper's figures), and the paper's own sensitivity table gives higher figures when more of the cats were feral. Because those 8,600 are cats that would have been born, the rate already includes the births the model projected through 2005, and the avoided costs arrive over about a decade rather than in the year of the surgery.
Apply that rate to North Carolina's numbers and the result is close to break-even: 0.32 times $381 is about $122 in average shelter cost avoided per surgery (undiscounted and spread over about a decade), against a $111 average eligible cost. Births the model did not project, including any after 2005, are not counted, and the comparison uses average, not marginal, shelter cost, which cuts the other way. Treat that as an illustration, not an NC estimate. The Kass study covered cats only, in one California county, using a statistical model rather than a controlled trial, and the authors wrote that confounding factors "cannot be ruled out."
Because the true rate is uncertain, the table runs the same arithmetic across a range of assumptions. Each cell is the average shelter cost avoided per surgery, under the assumption in its row and column.
| Shelter intakes avoided per surgery (assumed) | Low-cost shelter, $254 per animal | Median shelter, $381 per animal | High-cost shelter, $599 per animal |
|---|---|---|---|
| 0.10 (1 in 10) | $25 | $38 | $60 |
| 0.25 (1 in 4) | $63 | $95 | $150 |
| 0.32 (Kass et al. 2013) | $81 | $122 | $192 |
| 0.50 (1 in 2) | $127 | $191 | $299 |
| 1.00 (1 for 1) | $254 | $381 | $599 |
Read across the table. At the California study's rate, a surgery covers its $111 average eligible cost at median and higher-cost shelters but not at low-cost ones. At 1 in 10 it covers that cost nowhere, and from 1 in 4 upward every cell exceeds the $42 the state paid (counties paid the rest). If only half of average shelter cost is truly avoidable when intake falls (an illustrative assumption with no NC source behind it), every cell halves, and the California study's rate at the median gives about $61 per surgery: below the $111 average eligible cost, above the $42 state share. The defensible public claim is therefore a range, not a single return-on-investment number.
Why Prevention Compounds: Litters, Not Folklore
Why can one surgery prevent more than one intake? Because each litter prevented also prevents the litters its animals would have had. The California estimate already counts that effect inside its 1994 to 2005 window; births the model did not project, including any after 2005, are not counted anywhere in the math above. The exponential "offspring" totals often used to make this point assume no animal ever dies, so this guide uses measured figures instead.
The best field data for cats comes from North Carolina itself. A study of free-roaming cats in managed colonies by researchers at NC State's College of Veterinary Medicine (Nutter, Levine and Stoskopf, 2004) found that cats produced a mean of 1.4 litters a year with a median of 3 kittens per litter. That is about 4 kittens a year from one free-roaming female. The same study found that 75 percent of kittens died or disappeared before 6 months of age, which leaves about 1 surviving kitten per female per year (our arithmetic from the study's figures). Cats can reach puberty as early as 4 months and can come back into heat within 4 to 6 weeks of giving birth, according to the Merck Veterinary Manual.
| Reproduction fact | Cats | Dogs |
|---|---|---|
| Age at puberty | 4 to 12 months | 6 to 24 months, earlier in small breeds |
| How often a female can breed | Seasonal cycles every 14 to 21 days; can return to heat 4 to 6 weeks after giving birth | Heat about every 6 to 7 months (range 5 to 12) |
| Litters and litter size | Free-roaming NC cats: mean 1.4 litters a year, median 3 kittens | Mean litter 5.4 puppies (3.5 miniature to 7.1 giant breeds) |
| Young that survive | About 25% of free-roaming kittens still accounted for at 6 months | No comparable field figure found |
For dogs, a female typically comes into heat about every 6 to 7 months, according to a veterinary review by Concannon (2011), and a study of more than 10,000 purebred litters registered in Norway found a mean litter size of 5.4 puppies, from 3.5 in miniature breeds to 7.1 in giant breeds. So an unspayed female dog can have up to two litters a year in theory, and an average litter is about five puppies. We could not find a source for how many litters owned North Carolina dogs actually produce in a year, so we do not multiply these figures into a total.
These facts support a narrower point: one spay can prevent not one litter but several, year after year, for an animal that would otherwise breed. The break-even math above is conservative in one respect: births the model did not project, including any after 2005, are not counted. In another respect it is generous, because it uses average shelter cost, and a shelter saves less than the average when one fewer animal arrives.
What the Studies Show About Funded Spay/Neuter
The research on whether subsidized spay/neuter lowers shelter intake is encouraging for cats and mixed for dogs. We found no published evaluation of North Carolina's statewide program, and that gap should be closed. The table summarizes the peer-reviewed evidence with each study's own limits.
| Study | Place and program | What it found | Limits |
|---|---|---|---|
| Kass, Johnson and Weng, 2013 | Santa Clara County, CA; cat sterilization vouchers | Modeled about 8,600 cat intakes avoided from 1994 to 2005, counting cats that would have been born; about $2.15 million in avoided shelter cost against about $620,000 in surgery costs | Cats only; modeled, not measured; costs not discounted; confounders possible |
| Scarlett and Johnston, 2012 | Transylvania County, NC; subsidized clinic opened 2005 | Cat impoundments and euthanasia fell significantly after the clinic opened | An existing decline in dog impoundments did not speed up; key data were unavailable |
| White, Jefferson and Levy, 2010 | New Hampshire; statewide program from 1994 for low-income owners' pets and shelter adoptees | Cat intake and euthanasia fell significantly after program onset | The cat decline appears to begin before the program; no decrease for dogs |
| White, Jefferson and Levy, 2010 | Austin, TX; EmanciPET program in targeted areas | Significantly lower rate of increase in dog and cat intake and euthanasia in program areas | Intake still rose, just more slowly |
| Levy, Isaza and Scott, 2014 | Alachua County, FL; targeted community cat sterilization plus adoption | Cat impoundment from the target area fell 66 percent, against 12 percent elsewhere | Community cats, not owned pets; two-year study |
In these studies, cat intake fell or grew more slowly after funded, targeted spay/neuter began. The dog results are weaker, and these studies do not test why; one untested possibility is that dogs reach shelters through a different mix of routes than the owned pets these programs mostly serve. The Kass ratio of about 3.5 to 1 (our calculation, $2.15 million divided by $620,000) rests on a $23.21 surgery cost assumed constant from 1994 to 2005, avoided intakes accumulated over the program's 12-year life and a $250 shelter contract price per cat. It is specific to one county's cat program, and it is the only peer-reviewed dollar-for-dollar figure we found for a spay/neuter program for owned pets. Studies of feral cat programs, such as Hughes et al. (2002) in Florida, compare costs differently. Community cat programs are a separate story with their own math, which we keep in our guide to funding TNR in North Carolina.
North Carolina Now Funds Half the Surgeries It Did in 2014
If the evidence points toward more prevention, North Carolina's program has been heading the other way, and the department's own reports show when the turn came. In 2014, according to the department's own legislative report, 41 counties and cities claimed reimbursement for 11,873 spay/neuter procedures. In 2025, the program covered 5,938. That is almost exactly half.
The department ties the biggest drop to a rule change. Through the first three quarters of 2015, a "low-income person" under the program was anyone with household income below 300 percent of the federal poverty guidelines, or anyone who qualified for public assistance. In September 2015 the General Assembly redefined it as household income below 100 percent of the federal poverty limit, with no public-assistance route. In at least one of the first three quarters of 2015, 43 counties and cities took part in the program. In the fourth quarter, when the change took effect, participation fell to 26, according to the department's 2017 legislative report. In July 2016 lawmakers added the public-assistance route back, but the income limit stayed at 100 percent, and participation has not returned to its 2013 to 2015 level. In 2025 it ran at 26 to 27 local governments per quarter.
It is worth being precise about what the drop means. The 2015 change shrank the pool of eligible owners and, by the department's reading, the number of counties taking part. It did not mean fewer low-income pets needed surgery. Nationally, high-volume spay/neuter clinics have performed fewer surgeries since the pandemic, and a 2025 study in Frontiers in Veterinary Science estimated that, if the trend at 212 high-volume clinics held nationwide, the U.S. shortfall had passed 3.7 million surgeries by mid-2023. Our inference, not the study's finding: fewer surgeries now likely mean more litters later, and some of those animals will end up at the back end.
37 Cents of Each Dollar Requested
The program's second problem is money. In 2025, counties requested $682,056 in reimbursement and the state paid $250,954. That is about 37 cents of every dollar requested, or 38 cents of every dollar the state judged eligible after applying its per-procedure caps. That left $408,672 in eligible claims unpaid. Full reimbursement is not guaranteed, the department's own FAQ says.
Measured against eligible costs, the paid share was 58.2 percent in 2022 (per the department's 2022 reimbursement breakdown) and rose to 59.9 percent in 2023. It then fell to 50.6 percent in 2024 and 38.0 percent in 2025, as eligible claims rose and payments fell. In the first half of 2026 it was 35.6 percent. Every unpaid dollar is one a county has to absorb, pass on through copays, or plan around by doing fewer surgeries next year.
Where does the account's money come from? Its 2025 funding was the $250,000 recurring appropriation (part transferred in December 2024, per the department's Dec. 30, 2025 memo to counties) plus $122,228 in plate fees from the $20 share of each "I Care" Animal Lovers license plate fee, $372,228 in all. The law also lets the department use up to 20 percent of the account for education and up to 20 percent for administration, which may account for part of the gap between the $372,228 available and the $250,954 paid to counties; we did not find a published breakdown of how the 2025 difference was used. Our explainer on what the I Care plate actually funds covers the plate side in detail.
Against the back end, the difference in scale is large. Reporting NC shelters spent about $180 for every $1 that flowed into the state spay/neuter account in 2025 (our calculation), a comparison of scale rather than a return on investment. The chart lives in our 2025 county shelter report. The same report has the outcome side: reporting shelters took in 150,784 dogs and cats in 2025 and euthanized 39,202 of them, 26.0 percent, and our page on how many animals NC euthanizes puts that number in context.
How Maryland Pays for It: A Fee on Pet Food Products
North Carolina is not short of models. Our survey of states that got spay/neuter funding right covers several. The one that fits the petition's first ask most closely is Maryland's.
Maryland charges pet food companies a fee on each brand or product of dog and cat food registered in the state, and since October 2015 that fee has been $100 per product per year. By law the money goes into a special, nonlapsing Spay/Neuter Fund whose stated purpose is to reduce shelter overpopulation and cat and dog euthanasia. The fund makes grants to local governments and to animal welfare organizations. North Carolina's program, by contrast, can only reimburse cities and counties.
North Carolina also registers pet food. It charges $5 per product per year ($12 for canned pet food), and that fee is not one of the Spay/Neuter Account's funding sources under G.S. 19A-62. From 2010 to 2015, the program's money came from a planned $250,000-a-year transfer of surplus pet food and feed licensing receipts; since 2015 it has been a direct appropriation in the state budget, with no dedicated revenue behind it.
| Item | North Carolina | Maryland |
|---|---|---|
| Fee per registered dog or cat food product | $5 a year ($12 canned), not dedicated to spay/neuter | $100 a year, paid into the Spay/Neuter Fund |
| Main funding source | $250,000 appropriation plus "I Care" plate fees | The pet food product fee |
| Money raised, most recent year | $372,228 available for 2025 | $1,183,600 collected (fiscal 2025) |
| Surgeries funded, most recent year | 5,938 reimbursed (calendar 2025) | 14,379 approved (fiscal 2025) (8,030 completed by June 30, 2025) |
| Who can receive money | Cities and counties only | Local governments and animal welfare organizations |
Two caveats go with that table. First, Maryland's own annual report does not claim the fund has lowered shelter intake; it says intake has risen since 2021, faster than euthanasia. What the fund buys is a dedicated source of prevention money that does not depend on each year's budget (the current law runs through September 2032). Second, no one has published how many dog and cat food products are registered in North Carolina, so we cannot say what a $100 fee would raise here. A records request to the department's feed program could answer that.
What We Left Out, and Why
Three widely repeated figures do not appear in this guide.
"One cat can produce 370,000 kittens in seven years." This and its variants come from theoretical compounding that assumes every kitten survives and breeds. The NC State study above found 75 percent of free-roaming kittens died or disappeared before 6 months. PolitiFact rated one version (420,000 kittens from one male cat in five years) Pants on Fire. The state veterinarian it consulted recalled the number from a pamphlet describing "ideal conditions."
"One dog can produce 67,000 puppies in six years." The flyer that carries it starts from a male and a female and says itself that the chart "is based on theory." There is no study behind it.
"Every $1 spent on spay/neuter saves $X." The versions we traced lead back to a 1990 Minnesota commission report quoting an unlocated study from the early 1970s, or to advocacy pages with no source at all. The only traceable peer-reviewed ratio we found for an owned-pet spay/neuter program is the Kass figure above, for one county's cat program (feral cat studies compare costs differently), and we have used it only as an illustration.
What Commissioners and Legislators Can Do
The fiscal case points to two decisions, one in Raleigh and one in each county seat.
At the state level, fund prevention on purpose. The petition asks the General Assembly to create a dedicated, self-sustaining spay/neuter fund on the Maryland model, and to raise the appropriation to the Spay/Neuter Account so it can meet county demand. At 2025 participation levels, paying every eligible claim would have taken $408,672 more than the state paid (our calculation). That figure assumes 2025 participation; more counties or wider eligibility would raise it.
At the county level, use the program that already exists. A county must file its annual shelter report by March 1 to stay eligible for reimbursement. A county that runs a program can claim state money for low-income residents' surgeries, and a county with a shelter above the state median has the strongest fiscal case of all, because each prevented intake is worth more there on average cost. Commissioners can check their county's 2025 numbers and local clinics on our county pages, and residents can find a provider through our low-cost spay/neuter directory or our county-by-county coverage map.
For residents, the ask is short. Sign the petition, then email your legislators with one sentence: in 2025, North Carolina's spay/neuter program surgeries averaged about $111 in eligible cost and the state paid only about $42 of that, while the median reporting shelter spent $381 per animal handled, a figure that includes buildings and staff, and the state covered 37 cents of every dollar counties requested. Bring the same numbers to a county commissioners meeting.
Frequently Asked Questions
If North Carolina's program prevented shelter intakes at the rate one California study modeled, about 1 for every 3.1 surgeries over roughly a decade (our calculation from its figures), it would roughly pay for itself on average shelter cost. In 2025 program surgeries averaged about $111 in eligible cost, of which the state paid about $42, and reporting NC shelters spent a median of $381 per animal handled, so a surgery breaks even on average cost if about 1 in 3.4 prevents one intake (our calculation). The $111 counts only capped direct surgical costs, while the $381 includes all shelter overhead. That California study covered cats only and used a model, and real savings depend on how much shelter cost is truly avoidable when intake falls, which no NC study has measured.
In calendar year 2025 the state Spay/Neuter Program covered 5,938 procedures. Counties documented $659,626 in eligible costs, an average of about $111 per surgery (our calculation), and the state paid $250,954, about $42 per surgery (our calculation). The rest fell to counties and their partners. For 2026 the maximum the state will reimburse ranges from $120.11 for a cat neuter to $220.80 for a dog spay.
In the 2025 state shelter report, as re-issued October 12, 2026, the 58 facilities that reported a cost per animal had a median of $381, and half fell between $254 and $599. Each shelter calculates the figure itself, most likely as total yearly spending divided by animals handled (neither the statute nor the form defines it). It is an average that includes buildings and staff, so a shelter saves less than $381 when one fewer animal arrives.
Pet owners who receive benefits from a state public assistance program or whose household income is below 100 percent of the federal poverty guidelines. The program pays cities and counties, not owners or veterinarians, so you apply through a participating local program. Local programs offer the surgeries at reduced cost; any charge to the owner is set locally, not by the state. About 26 to 28 local governments took part each quarter in 2025 and early 2026. Our county pages list local options.
No. That figure comes from theoretical compounding that assumes every kitten survives and breeds. A North Carolina State University study of free-roaming cats found a mean of 1.4 litters a year with a median of 3 kittens, and 75 percent of kittens died or disappeared before 6 months. That is about 4 kittens a year per female, with about 1 surviving (our calculation).
Maryland charges a $100 annual fee on each dog and cat food product registered in the state and puts the money in a dedicated, nonlapsing Spay/Neuter Fund. In fiscal 2025 it collected $1,183,600 and approved grants for 14,379 surgeries. North Carolina charges $5 per registered feed product ($12 canned), and that fee is not a funding source for the state Spay/Neuter Account.
Sources
- NC Department of Agriculture and Consumer Services, Spay and Neuter Reports: 2025 CY Public Animal Shelter Report (Excel and PDF, file re-issued October 12, 2026); 2023, 2024 and 2025 Spay/Neuter Reimbursement Summaries; 2026 1st and 2nd Quarter Reimbursement Summary; Memo to Counties, December 30, 2025.
- NC DACS, 2022 1st to 4th Quarter Reimbursements, breakdowns by quarter, all entities (5,793 procedures; $517,060.25 eligible; $301,023.75 reimbursed).
- NC DACS, Memo to Counties, December 30, 2025 (funding transfers for 2025).
- NC DACS, Public Animal Shelter Report Form 2025.
- NC DACS, Spay and Neuter Program FAQs (2026 maximum reimbursements; reimbursement not guaranteed; payments to local governments only).
- NC DACS, Spay and Neuter Program ("I Care" plate share).
- NC DACS, Spay/Neuter Program Legislative Report, Calendar Year 2014.
- NC DACS, Spay/Neuter Program Legislative Report, Calendar Year 2017.
- North Carolina General Assembly, G.S. Chapter 19A, Article 5 (G.S. 19A-60 to 19A-66), Spay/Neuter Program.
- North Carolina General Assembly, G.S. 106-284.34, commercial feed registration.
- Maryland General Assembly, Md. Code, Agriculture 2-1602 and 2-1603.
- Maryland Department of Agriculture, Spay and Neuter Grants Program Annual Report FY2025 (August 2025).
- Kass PH, Johnson KL, Weng HY. Evaluation of animal control measures on pet demographics in Santa Clara County, California, 1993-2006. PeerJ 2013;1:e18.
- Scarlett J, Johnston N. Impact of a subsidized spay neuter clinic on impoundments and euthanasia in a community shelter and on service and complaint calls to animal control. J Appl Anim Welf Sci 2012;15(1):53-69.
- White SC, Jefferson E, Levy JK. Impact of publicly sponsored neutering programs on animal population dynamics at animal shelters: the New Hampshire and Austin experiences. J Appl Anim Welf Sci 2010;13(3):191-212.
- ASPCA and PetSmart Charities, Solutions to Overpopulation of Pets: State-Funded Spay/Neuter in New Hampshire (September 2007).
- Hughes KL, Slater MR, Haller L. The effects of implementing a feral cat spay/neuter program in a Florida county animal control service. J Appl Anim Welf Sci 2002;5(4):285-298.
- Levy JK, Isaza NM, Scott KC. Effect of high-impact targeted trap-neuter-return and adoption of community cats on cat intake to a shelter. Vet J 2014;201(3):269-274.
- Guerios SD, Clemmer G, Levy JK. The pandemic's cruel aftermath: progressive decline in spay/neuter capacity. Front Vet Sci 2025.
- Nutter FB, Levine JF, Stoskopf MK. Reproductive capacity of free-roaming domestic cats and kitten survival rate. JAVMA 2004;225(9):1399-1402.
- Borge KS, Tønnessen R, Nødtvedt A, Indrebø A. Litter size at birth in purebred dogs: a retrospective study of 224 breeds. Theriogenology 2011;75(5):911-919.
- Concannon PW. Reproductive cycles of the domestic bitch. Anim Reprod Sci 2011;124(3-4):200-210.
- Merck Veterinary Manual, Features of the Reproductive Cycle (table).
- PolitiFact, Central Falls, R.I. animal control says one male cat can father 420,000 kittens in just five years (Feb. 2, 2013).
- North Shore Animal League America and SpayUSA, dog population flyer (cited only to show the 67,000 figure's own caveat).
- Minnesota Animal Population Control Study Commission, Report to the Legislature (Feb. 7, 1990) (cited only to show the origin of "every $1 saves" figures).
Methodology note: per-surgery figures divide the 2025 reimbursement summary's eligible and reimbursed totals by its 5,938 procedures; the requested total ($682,056.02) is the sum of the summary's county rows, or about $115 per procedure. Eligible cost is direct surgical cost after the state's per-procedure caps and excludes county administrative and capital costs; shelter cost per animal is fully loaded. Shelter cost figures are the median and quartiles of the cost per animal that 58 facilities reported in the 2025 file re-issued October 12, 2026. Break-even and sensitivity figures are NC Pet Project arithmetic on average costs and are illustrations, not predictions.