Dog Population Management: Modelling

Data and facts from dog population management efforts and campagins.

Jump to: Comparison | CNVR Only

Highlights


Comparison of Dog Population Management Mechanisms

Jump to: Flexible Agent-Based Model (2023) | Strategies in Abruzzo, Italy

A Flexible Agent-Based Model (2023)

Background

  • Intervention Strategies:
    • Lethal Control: Dogs are caught and killed with no vaccination or release efforts.
    • Vaccination-only: Dogs are caught once in a lifetime and vaccinated against disease, no culling or sterilization.
    • Female-only CNVR: Only females are caught, vaccinated against disease, and sterilized while males remain untreated.
    • Male-inclusive CNVR: Both males and females are caught and vaccinated, and females are also sterilized.
  • Evaluation:
    • Standard capture rate: 300 dogs/month
    • Duration: 10-year burn-in and 10 years of intervention

Results

  1. Population Reduction:
    • Initial population: ~30,000 dogs
    • After 10 years of intervention:
      • Female-only CNVR: Lowest mean population (21,302 dogs)
      • Lethal Control: 21,560 dogs
      • Male-inclusive CNVR: 24,594 dogs
      • Vaccination-only: 25,486 dogs
    • None achieved a 50% population reduction.
    • Populations decreased by over 10% in all but the Vaccination-only scheme.
  2. Rebound Time:
    • Time for population to rebound to 90% after intervention:
      • Female-only CNVR: 4.66 years
      • Lethal Control: 2.10 years
      • Male-inclusive CNVR: 1.63 years
  3. Total Dog Deaths:
    • Female-only CNVR: Lowest (165,343 deaths)
    • Male-inclusive CNVR: 210,520 deaths
    • Lethal Control: 236,823 deaths
    • Vaccination-only: Highest (286,024 deaths)
  4. Puppy Population:
    • Percentage of dogs 6 months or younger:
      • Lethal Control: 25.59%
      • Vaccination-only: 23.76%
      • Male-inclusive CNVR: 18.19%
      • Female-only CNVR: 15.62%
  5. Vaccination Coverage:
    • Higher in Female-only CNVR and Male-inclusive CNVR than in Vaccination-only (27.19%, 27.46%, and 24.47% respectively)
    • Longer immunity duration (36 months) resulted in greater coverage (28.13%) compared to shorter duration (12 months, 12.26%).
  6. Capture Rates:
    • Lowest population sizes:
      • Lethal Control with 500 dogs/month capture: 16,885 dogs
      • Female-only CNVR with 500 dogs/month capture: 18,982 dogs
    • Intermediate population sizes:
      • Capture rates of 300 dogs/month: 20,869 to 21,505 dogs
    • Highest population sizes:
      • Capture rates of 100 dogs/month: 27,803 (Lethal Control) and 26,729 (Female-only CNVR)
  7. Intervention Duration:
    • Population reduction benefits lasted longer in Female-only CNVR compared to Lethal Control for all intervention durations.
    • Rebound time:
      • 5-year interventions: 4.98 years
      • 10-year and 15-year interventions: 5.04 years (differences non-significant)

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Management Strategies in Abruzzo, Italy

External link:
H.R. Høgåsen, C. Er, A. Di Nardo, P. Dalla Villa, Free-roaming dog populations: A cost-benefit model for different management options, applied to Abruzzo, Italy,
Preventive Veterinary Medicine, Volume 112, Issues 3–4, 2013, Pages 401-413, ISSN 0167-5877,
https://doi.org/10.1016/j.prevetmed.2013.07.010.

Background

  • In 1991, the Italian Parliament approved National Law n. 281 “Companion Animals and the Prevention of Strays,” which provides government protection and assistance to free-roaming dogs (FRD) and forbids euthanasia of unwanted dogs unless they are incurably ill or proven dangerous.
  • Despite mandatory registration since 1991, only half of the dogs were registered by 2004, though three-quarters of households were aware of the requirement.
Public Perception and Practices
  • In a 2004 interview in Teramo (TE), 90% of respondents believed FRDs were a problem.
  • 13% of respondents in the same interview allowed their dogs to roam free all the time.
  • Main reasons for dog abandonment in TE included loss of interest (65%) and difficulties in keeping the dog (23%), with a high proportion of dogs received as gifts (48%).
  • The yearly abandonment rate was 2.2%, based on national data from 2001 indicating 150,000 out of 6.9 million dogs were abandoned.
Sterilization and Shelter Utilization
  • In 2008, it was estimated that 16% of owned dogs (OD) were sterilized.
  • The municipal shelter of Pescara (PE) recorded an annual capacity utilization of 83–92% from 2000 to 2006.
  • Between 2000 and 2006, an average of 1016 dogs were captured annually in PE, with about 360 released as block dogs (BD).
  • Only 2% of respondents in TE considered euthanasia a better option than abandonment for unwanted dogs. Half believed abandoned dogs should be taken to a public shelter, and 45% thought new kennels should be built. However, both kennel delivery and euthanasia are strictly regulated, leading to common abandonment of unwanted dogs as strays.
Capture and Outcomes
  • The PE Local Veterinary Service (LVS) captured a mean of 514 dogs per year (range 239–536) from 2000 to 2006: 5% were euthanized, 8% kennelled, 38% adopted, and 49% converted to BD.
  • The TE LVS captured a mean of 526 dogs yearly from 2004 to 2006: 4% were euthanized, 14% kennelled, 45% adopted, 8% returned to owners, and 29% converted to BD.
International Comparisons
  • In Japan in 2000, about 10% of captured dogs were returned to their owners, with the remaining 136,238 dogs euthanized.
  • In Australia, dogs deemed unsuitable for rehoming or not sold within 28 days post-assessment are recommended for euthanasia.

Monetary Cost Assumptions

  • Converting a stray dog to a kennel dog (KD) or BD cost €375 in 2012, including catching (€100), a ten-day stay in a sanitary kennel (€120), sterilization (€70), microchipping (€25), vaccination (€25), medication (€20), and Leishmania testing (€15).
  • Converting an OD delivered to a kennel to a KD or BD cost €126 per dog in 2012, excluding catching and sanitary kennel stay.
  • Mean maintenance costs of a KD were €1,000, covering food, medication, vaccination, and labor.
  • The mean cost for euthanasia was €136 per dog, based on a mean body weight of 20 kg, including body disposal costs.

Population Dynamics

  • The destiny of captured stray dogs (SD) was estimated from TE and PE data: 5% euthanized (mostly due to incurable disease), 5% returned to owners, 40% adopted, 10% sent to kennels, and 40% returned as BD. Among BD, 5% were already BD, and 35% were converted from SD.

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CNVR Only

Overview

Jump to: Agent-Based Model, India (2020) | Kerman, Iran

  • While there is no definitive rule for the proportion of the dog population that must be neutered to control and stabilize it, a common industry benchmark is 70% of the females, similar to the threshold for rabies vaccination.  (Source, 2019)

Agent-Based Model, Inspired by India (2020)

Study Overview

  • Population Assumptions:
    • Human population: 1,000,000
    • Human:dog ratio: 33:1
    • All dogs aged 13 months or older at initial setup
    • Adult dog carrying capacity used for simulating density-dependent juvenile mortality, but not explicitly enforced
    • Model run for 5 years (burn-in period) to achieve stable age distribution
    • 100 iterations per scenario
  • Metrics for Assessment:
    • Dog abundance (pre-breeding population in September)
    • Annual recruitment into the adult class
    • Anti-rabies vaccination coverage

Model Applications

Base-Case Scenario (Status-quo)
  • Population Trends:
    • Year 5: 35,183
    • Year 30: 42,879 (continuous increase)
  • Adult Dog Abundance:
    • Year 16: 30,186 (reached carrying capacity)
    • Year 30: 31,956 (remained over carrying capacity)
  • Annual Recruitment:
    • Year 5: 9,412
    • Year 30: 11,090
Best-Case Scenario – Low Intensity ABC Effort
  • Implementation:
    • 1 ABC center (~250 surgeries/month) for 5 years
    • All dogs easily catchable
    • Average surgeries: 14,687
    • Costs: US$170,426
  • Population Trends:
    • Year 5: 35,121
    • Year 14: 31,254 (decrease up to year 14, then increase)
    • Year 20: Pre-intervention levels
    • Year 30: 40,686
  • Adult Dog Abundance:
    • Year 6: 26,656
    • Year 15: 23,830 (decrease up to year 15, then increase)
    • Year 29: 30,145
  • Annual Recruitment:
    • Year 5: 9,359
    • Year 15: 8,439 (decreased till year 15, then increased)
    • Year 30: 10,689
  • Vaccination Coverage: Max 8%, waned rapidly within 1 year post-intervention
Best-Case Scenario – Moderate Intensity ABC Effort
  • Implementation:
    • 2 ABC centers (~500 surgeries/month) for 5 years
    • All dogs easily catchable
    • Average surgeries: 29,380
    • Costs: US$340,918
  • Population Trends:
    • Year 5: 34,980
    • Year 15: 20,306 (decrease up to year 15, then increase)
    • Year 26: 34,447 (pre-intervention levels)
    • Year 30: 37,650
  • Adult Dog Abundance:
    • Year 6: 26,629
    • Year 15: 15,561 (decrease up to year 15, then increase)
    • Year 27: 26,310
    • Remained below carrying capacity throughout the model
  • Annual Recruitment:
    • Year 5: 9,297
    • Year 15: 5,105 (decrease up to year 15, then increase)
    • Year 30: 10,111
  • Vaccination Coverage: Max 18%, waned rapidly within 1 year post-intervention
Best-Case Scenario – High Intensity ABC Effort
  • Implementation:
    • 3 ABC centers (~750 surgeries/month) for 5 years
    • All dogs easily catchable
    • Average surgeries: 42,608
    • Costs: US$492,682
  • Population Trends:
    • Year 5: 34,647
    • Year 20: 1,447 (decrease up to year 20, then gradual increase)
    • Year 30: 3,032
  • Adult Dog Abundance:
    • Year 6: 26,394
    • Year 25: 1,161 (decrease up to year 25, then increase)
    • Year 30: 2,248
    • Remained below carrying capacity throughout the model
  • Annual Recruitment:
    • Year 5: 9,247
    • Year 15: 87 (decrease up to year 15, then increase)
    • Year 30: 1,019
  • Vaccination Coverage: Max 35%, waned rapidly within 1 year post-intervention
  • Additional Observations:
    • Nine out of 100 iterations had >10,000 dogs (max value: 28,136) in Year 30
    • Only six out of 100 iterations had adult dog abundance above 10,000 in the 4th assessment interval
Real World Scenario – High Intensity ABC Effort
  • Implementation:
    • 3 ABC centers (~750 surgeries/month) with capture heterogeneity
    • Estimated 40% dogs easily catchable, 60% require additional effort
    • 5% of dogs designated as inaccessible for ABC intervention
    • Net annual immigration of 1%
    • Average surgeries: 21,099
    • Costs: US$243,393
  • Population Trends:
    • Year 5: 35,829
    • Year 15: 29,150 (decrease up to year 15, then increase)
    • Year 30: 42,095
  • Adult Dog Abundance:
    • Year 6: 27,442
    • Year 14: 21,945 (decrease up to year 14, then increase)
    • Year 28: 30,874 (surpass carrying capacity)
    • Year 30: 31,444
  • Annual Recruitment:
    • Year 5: 9,386
    • Year 15: 7,556 (decrease up to year 15, then increase)
    • Year 30: 10,878
  • Vaccination Coverage: Max 9%, waned rapidly within 1 year post-intervention

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Kerman, Iran Population Estimate & Female Sterilization Impact Modeling

(Source, 2022)

Background

  • Dog ownership in Iran is traditionally uncommon due to social and cultural factors.
  • Recently, pet dog ownership has increased in larger metropolitan areas.
  • Most owned dogs are sheep or guard dogs.
  • Low responsible ownership and adoption rates result in many abandoned puppies.
  • High numbers of free-roaming dogs cause human–dog tensions.
  • Between 1993 and 2013, there were 230,019 animal bite cases (>90% from dogs), with an incidence of 13.2 per 1000 population.

Population Estimate and Demographics

  • Estimated free-roaming dog (FRD) population: 6,781 (1.2 dogs per 100 people, 5.8 dogs per km of street survey, 30.8 dogs/km²).
  • Female dogs are more commonly seen in the city than in the suburbs.
  • City dogs are more likely to have normal/overweight body conditions compared to suburban dogs.
  • 37% of female dogs were pregnant or lactating, with no significant difference between city (36.8%) and suburbs (37.2%).
  • Dog location distribution in the city: vacant lots (46.2%), streets/sidewalks (24.4%), alleys (24.4%), public parks (4.2%), and next to restaurants/garbage bins (0.8%).

Population Management Modelling

  • No intervention scenario:
    • Dog population projected to increase by 2.02 times in 5 years and 2.86 times in 10 years (from 6,781 to 13,665 in 5 years and 19,376 in 10 years).
  • Intervention scenario (annual female dog spaying rates):
    • 5-year projections:
      • 10% spaying: population increases by 1.53 times
      • 30% spaying: population decreases to 0.89 times
      • 50% spaying: population decreases to 0.56 times
      • 60% spaying: population decreases to 0.47 times
      • 70% spaying: population decreases to 0.41 times
    • 10-year projections:
      • 10% spaying: population increases by 2.03 times
      • 30% spaying: population decreases to 0.81 times
      • 50% spaying: population decreases to 0.32 times
      • 60% spaying: population decreases to 0.22 times
      • 70% spaying: population decreases to 0.16 times

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