Moving Towards "No-Kill": Data Analysis of Colorado Shelter Trends Over the Last 9 Years (2016–2024)
The analysis is focused on tracing key trends in the dynamics of animal intake, positive outcomes, transfers, and the overall strain on Colorado's shelter system.
Over the last few years, a significant reduction in negative outcomes for animals has been achieved thanks to the immense efforts of shelters, rescue organizations, and community advocacy (as well as the implementation of the No Kill Equation).
Live Release Rate (LRR)
Next chart shows how different animal groups are progressing toward the no-kill benchmark, represented by a 90% Live Release Rate (LRR). LRR measures the percentage of animals that leave the shelter alive through adoption, return to owner, or transfer, making it a key indicator of shelter performance.
Each bubble reflects the total number of outcomes, helping visualize both the scale of operations and the success in achieving positive results across years.
Each bubble reflects the total number of outcomes, helping visualize both the scale of operations and the success in achieving positive results across years.
Live Release Rate (LRR) =
Live Outcomes ÷
Total Outcomes × 100%
Transfers vs. Negative Outcomes
In recent years, Colorado shelters have welcomed a growing number of animals transferred from out of state—often as part of lifesaving efforts to help pets from overcrowded or under-resourced regions. While this reflects Colorado’s commitment to animal welfare, it raises important questions: Is the state’s own shelter system coping with the increased volume? And are local animals being affected as a result?
Negative Outcome Rate =
Negative Outcomes ÷
Total Intake × 100%
This metric helps us understand how many animals experience negative outcomes - such as euthanasia, death, or disappearance - relative to the total number of animals entering the shelter system. Tracking this rate over time can reveal whether shelters are becoming more or less effective at ensuring positive outcomes for the animals in their care.
Conclusion
Dogs
The number of dogs transferred into Colorado remained high between 2016 and 2024. However, Negative Outcomes dropped sharply in 2019 and stayed low afterward. This clearly shows that Colorado shelters can help dogs from other states without increasing deaths for local pets. Specifically, the negative outcome rate for adult dogs dropped from about 19% in 2018 to about 7% in 2019, and the rate for puppies remained consistently low, below 2%.
Cats
From 2016 to 2020, as transfers of cats increased sharply, the number of Negative Outcomes fell to its lowest point. This means that receiving transferred cats helped the system save more lives overall. The negative outcome rate for adult cats notably declined from over 20% in 2018 to around 10% in 2020. However, after 2020, Negative Outcomes started to slightly increase, which might signal new stress on the system. The kitten negative outcome rate, while lower than adult cats, shows a slight increase after 2020 as well, from a low of about 3% to about 5% by 2024.
Other Animals
The number of Negative Outcomes is generally much higher than the number of transfers in this category. A noticeable spike in transfers happened in 2022, which was connected to the Avian Flu outbreak. This suggests that Colorado’s system responded to a regional crisis by taking in animals needing urgent help. The negative outcome rate for "birds" spiked dramatically in 2020 to almost 40%, then fell sharply, highlighting the volatility in this category, potentially due to small numbers of intakes or specific crises. The category reptile
and amphibian generally maintained one of the lowest negative outcome rates among Other Animals, mostly below 5%.
Adoption Trends Over Time
Adoption is the main way animals leave shelters and find a new home, so it's a very important sign of success.
This part looks at how adoption rates (the number of animals adopted) have changed over time.
Adoption Rate =
Number of Adoptions ÷
Total Intakes × 100%
If the adoption rates suddenly go up or down, it might be because of things happening outside the shelter, or it might show that the shelter needs more help and community involvement.
Conclusion
Dogs
The total number of dog adoptions has slowly gone down from 2018 to 2024. In 2018, there were around 64,000 adoptions, but in 2024, there were about 53,600. Adult Dog adoptions are higher than Puppy adoptions every year, but both categories show a general decline over time. For example, Adult Dog adoptions went from over 43,500 in 2018 to around 33,300 in 2024. Puppy adoptions had a peak around 2020 (near 27,000) and then decreased to about 20,000 in 2023 and 2024. This decline is probably because the cost of pet care (food and vets) is much higher now. Also, people are surrendering dogs, especially large ones, due to housing restrictions and behavioral issues after the pandemic.
Cats
The total number of cat adoptions has generally increased from 2016 to 2022. Cats are often cheaper and have fewer housing rules than dogs, making them easier to adopt. Better shelter programs, like Trap-Neuter-Return (TNR), also helped more cats be ready for adoption. It went from about 40,000 in 2016 to a high of almost 54,000 in 2022. Kittens and Adult Cats had similar numbers from 2021 to 2024. Before 2021, Adult Cat adoptions were consistently higher. Both categories reached their highest adoption numbers in 2022 (around 27,000 each) and slightly decreased in the following two years.
Other Animals
Adoptions of Small Mammals are the highest every year. They had a peak of over 4,000 adoptions in 2022 and were always above 2,000. Rabbits had peaking around 1,500 in 2022. Adoptions of Birds and Reptiles & Amphibians are much lower, usually below 1,500. The trends for all these smaller animal groups show an increase in adoptions around 2021-2022, followed by a slight drop in 2023 and 2024.
Overall Trends
Over the years, the percentage of cat adoptions has been increasing compared to dog adoptions. In 2016, dogs were almost 60% of all adoptions. By 2022, this gap was much smaller: dogs were 52% and cats were 48%. This shows that cats are becoming a larger part of the total animal adoptions. The total number of adoptions for all animals was highest in 2022, reaching about 112,700 (53,855 cats + 58,865 dogs). After 2022, the total number of adoptions slightly decreased. The number of dogs and cats is likely to decline after 2022, primarily due to rising costs and economic instability, which has made pet ownership prohibitively expensive for families. At the same time, many shelters have seen an increase in animal surrenders due to housing issues, high veterinary costs, and behavioral issues with "pandemic animals".
Return-to-Owner (RTO) Rates
Return-to-owner (RTO) rates measure how often lost pets are reunited with their families, a key factor in reducing shelter overcrowding. This section examines RTO trends over time, particularly for dogs and cats.
RTO Rate =
Returned to Owner (RTO) ÷
Stray Intake × 100%
Stray Intake % =
Stray Intake ÷
Total Intake × 100%
These two metrics help assess how effectively shelters reunite stray animals with their owners and what proportion of the total number of animals taken in are stray. A high RTO indicates a high rate of reunification, while the stray intake rate indicates the proportion of stray animals admitted to a shelter.
Conclusion
Dogs
Adult dogs have a high return-to-owner (RTO) rate, between 69% and 76%, meaning most stray adult dogs are found by their owners. Puppy RTO rates are lower (17–27%). Dog adoptions dropped in 2020 but have stayed stable since. Many puppies in shelters are likely lost pets, not strays, and their adoption rate is also low (around 10-20%).
Cats
Cats have low RTO rates- about 20% for adults and only 3% for kittens-which shows that most cats in shelters are strays, not lost pets. However, adoption rates for both adult cats and kittens have increased from 2020 to 2024, meaning more cats are entering shelters and finding homes.
Why RTO Rates are high in Colorado
Many shelters and vet clinics in Colorado offer low-cost microchipping, often together with spay/neuter services. State law (PACFA) requires shelters to hold stray animals for at least 5 days before adoption, giving owners time to find them. Large shelters use shared online tools like 24Petconnect and Petco Love Lost to help reunite pets with their families. Shelters and rescue groups also work together more closely now, helping animals return home or move to places where they are more likely to be adopted.
Intake Categories & Shifts Over Time
Animal intake patterns show how and why animals enter shelters, and how these reasons change over time. This section examines changes in animal intake, owner surrenders, and shelter placements to understand broader social and economic issues.
Conclusions
Dogs
From 2016 to 2023, most dogs entered shelters through out-of-state transfers and as strays. These two sources made up over 70% of all dog intakes. In 2024, things changed: out-of-state transfers dropped to 22.5% (the lowest ever), while stray dogs (42.0%) and owner surrenders (25.2%) reached their highest levels. This shows a growing problem with stray dogs and more challenges for local pet owners.
Cats
Stray cats continue to be the largest intake group, making up 42-50% of all cat intakes. Owner surrenders also stay high at around 30%, likely due to financial stress. Out-of-state transfers peaked in 2020 (25.3%) but dropped to 12.9% by 2024. At the same time, in-state transfers increased to 13.7%.
Other Animals
Most birds, rabbits, and other small animals are surrendered by their owners. In 2024, owner surrenders made up 73.2% of all intakes in this group. This pattern has stayed steady over the years.
Overall Trends
Between 2016 and 2019, stray animals made up about 40% of all shelter intakes. By 2024, that number rose again to 41.3%, but other categories also grew. Owner surrenders increased from 24.6% in 2016 to 30.0% in 2024, with a peak of 31.2% in 2023. This may be due to rising costs and housing problems. Out-of-state transfers were high from 2019 to 2021, reaching 33.5% in 2020. But by 2024, they dropped to 17.2%, while in-state transfers rose to 11.5% - the highest ever - showing that shelters are now focusing more on animals from their own region.
Positive Outcome Pathways
This section examines how animals leave shelters through adoption, rehoming, or surrender—both within and across state lines. Tracking the balance between these pathways helps understand whether shelters rely on one method or maintain a healthy mix. Understanding these trends helps determine where to invest in programs such as adoption assistance, foster care support, and community engagement.
Conclusions
Live Release Rate (LRR)
From 2016 to 2024, the LRR improved for both dogs and cats. For dogs, it rose from 86.2% to 93.0%, and for cats from 82.4% to 91.6%. The highest rates were during 2020-2021, when shelter activity was limited. Even after the pandemic, LRR stayed above 90%, showing better shelter practices.
Dogs
Adult dog adoptions dropped from 40,469 in 2016 to 33,306 in 2024, showing it’s harder to find homes for older dogs. Return-to-owner (RTO) rates stayed strong, with 20,000-24,000 dogs reunited each year. Puppy adoptions peaked in 2019–2020 and then stabilized around 20,000 in 2023-2024.
Cats
RTO for adult cats grew from 2,486 in 2016 to 3,594 in 2024, but numbers are still low compared to dogs. Kitten adoptions peaked in 2022-2024 with over 26,000 placements, making them the most adopted group. Transfers also increased in 2023-2024, helping more cats find homes.
Other Animals
Adoptions of other animals jumped from 7,515 in 2021 to 12,080 in 2022, then settled at 9,348 in 2024-still above pre-pandemic levels. RTO remains very low, as most of these animals are owner surrenders and rarely have ID or microchips.
Geographic and Community Variances
Shelter performance can vary significantly across counties and regions. This section highlight areas where progress is greatest and where additional support is needed. Identifying high-performing areas helps replicate successful strategies and direct resources where they will have the greatest impact.
Conclusions
Intake and Outcomes
El Paso and Denver lead in both total intake and total live outcomes. In large counties like Denver, El Paso, and Jefferson, many animals come from owner surrenders or out-of-state transfers. In top-performing counties, adoption is the most common positive outcome, followed by return-to-owner (RTO).
Dog vs Cat LRR
Across all counties with the biggest LRR gaps, dogs consistently have higher survival rates than cats. This shows shelters face more challenges finding positive outcomes for cats. The largest gap is in Elbert and Reno, where dog LRR is near 95%, but cat LRR is only around 50%-52%.
High Performing Counties
In counties like Montrose, Weld, and Morgan, both dogs and cats have high LRRs-above 90% for dogs and over 85% for cats. This points to strong shelter programs and effective population management.
Resource Utilization and Capacity
Shelters operate with limited physical and staffing resources, and this section examines how animal intake and outcomes compare to established capacity. This helps identify when excessive intakes are straining the system, leading to bottlenecks or increased mortality. Understanding these factors ensures that local animals are prioritized and allows shelters to responsibly transfer animals from other states.
About the Sankey Diagram
This diagram shows how animals move from intake types to outcomes. The numbers for intake and outcomes are grouped separately — we know how many animals came in and how many left, but we don’t know the exact path each animal took. The connections between intake and outcome are estimated to help visualize the overall flow. They don’t represent direct links between specific events.
Conclusions
1. Dramatic Decline in Euthanasia: This is the most significant change. From 2016 to 2024, dog euthanasia decreased by more than 58%, while cat euthanasia decreased by nearly 48%.
2. Increase in Cat Transfers: Cat transfers from out-of-state showed significant growth, nearly doubling from 4,758 in 2016 to 8,587 in 2024, indicating strengthening partnerships.
3. Decline in Out-of-State Dog Admissions: While out-of-state dog transfers were consistently high (approximately 30,000–36,000 from 2016 to 2020), they declined significantly by 2024.
4. Adoptions Stabilize at a High Level: After peaking in 2018-2020 (around 65,000 for dogs and 46,000 for cats), adoption volumes have adjusted downwards slightly (53,602 for dogs and 50,903 for cats in 2024), but remain stably high.
5. Owner Surrender Increase: Owner relinquished animal intake for cats has steadily increased (from 15,667 in 2016 to 19,457 in 2024), possibly reflecting growing owner pressure.
6. Dog RTO Success: The return-to-owner (RTO) rate for dogs remains high, albeit fluctuating (high was 25,223 in 2018, low was 18,225 in 2020), confirming the effectiveness of lost dog recovery programs.
7. Other Category Growth: The Other category saw a significant surge in intakes and adoptions in 2022 (13,974 Intakes; 12,079 Adoptions), which may be related to the post-pandemic surge in small mammal surrenders.
8. Cat Volumes Catch Up with Dogs: By 2024, total cat intakes (66,684) nearly matched and surpassed dog intakes in some recent years, showing that cats continue to be a significant challenge for Colorado shelters.
9. Pandemic Years (2020–2021) Bring Changes: 2020 saw a temporary overall decline in intakes for all groups, but euthanasia fell to historic lows, suggesting a shift in focus to animal rescue.
10. Overall Trend Toward a "No-kill" Model: Data clearly shows that Colorado shelters have made significant progress in reducing non-viable outcomes by successfully managing the influx of animals primarily through adoption and RTOs.
2. Increase in Cat Transfers: Cat transfers from out-of-state showed significant growth, nearly doubling from 4,758 in 2016 to 8,587 in 2024, indicating strengthening partnerships.
3. Decline in Out-of-State Dog Admissions: While out-of-state dog transfers were consistently high (approximately 30,000–36,000 from 2016 to 2020), they declined significantly by 2024.
4. Adoptions Stabilize at a High Level: After peaking in 2018-2020 (around 65,000 for dogs and 46,000 for cats), adoption volumes have adjusted downwards slightly (53,602 for dogs and 50,903 for cats in 2024), but remain stably high.
5. Owner Surrender Increase: Owner relinquished animal intake for cats has steadily increased (from 15,667 in 2016 to 19,457 in 2024), possibly reflecting growing owner pressure.
6. Dog RTO Success: The return-to-owner (RTO) rate for dogs remains high, albeit fluctuating (high was 25,223 in 2018, low was 18,225 in 2020), confirming the effectiveness of lost dog recovery programs.
7. Other Category Growth: The Other category saw a significant surge in intakes and adoptions in 2022 (13,974 Intakes; 12,079 Adoptions), which may be related to the post-pandemic surge in small mammal surrenders.
8. Cat Volumes Catch Up with Dogs: By 2024, total cat intakes (66,684) nearly matched and surpassed dog intakes in some recent years, showing that cats continue to be a significant challenge for Colorado shelters.
9. Pandemic Years (2020–2021) Bring Changes: 2020 saw a temporary overall decline in intakes for all groups, but euthanasia fell to historic lows, suggesting a shift in focus to animal rescue.
10. Overall Trend Toward a "No-kill" Model: Data clearly shows that Colorado shelters have made significant progress in reducing non-viable outcomes by successfully managing the influx of animals primarily through adoption and RTOs.
This report was created to highlight the importance of continuing progress toward Colorado’s no-kill goal. Behind every chart and data point are real animals whose lives are impacted by these efforts. What follows is a visual example of how the no-kill movement is actively saving lives.
