Modelling the challenges of managing free-ranging dog populations

Abstract

Free-ranging domestic dogs (FRD) are not only vectors of zoonoses of public health concern, but also pose direct threats to humans, livestock, and endangered wildlife. Many developing countries have struggled to control FRD, despite using both lethal and non-lethal methods. India has amongst the highest FRD populations globally and the highest incidences of dog-mediated human rabies, but only deploys Catch–Neuter–Vaccinate–Release (CNVR) for FRD control as a humane alternative to lethal methods, without evidence of it working successfully. Here, we use an agent-based dog population dynamics model to examine the time, effort, financial resources, and conditions needed to successfully control FRD in a typical urban setting. We simulate several scenarios, from an “ideal world” closed population with easily accessible dogs, to a more realistic open population with heterogeneity in catchability of dogs. In only one “best-case” scenario, CNVR resulted in a significant and lasting reduction in FRD, but with vaccination rates peaking only at 35%, which is half the WHO-recommended coverage. The customisable and portable modelling tool that we have developed allows managers to simulate real world processes and understand the expected effort needed to reduce regional dog populations, and assess methods for achieving effective anti-rabies vaccination coverage.

A Review and Analysis of the National Dog Population Management Program in Chile

“…SMART goals (Specific, Measurable, Attainable, Relevant and Time-bound) are a useful way to clearly determine if the project is on track for success and to select indicators for accomplishing each goal [50]. The presentation of the numbers of animals treated or sterilized, the amount of money spent, or the number of municipalities participating, while it does show a point-in-time intervention, does not necessarily constitute success [31]. Arguably, the cost of collecting baseline data in every community prior to initiating interventions is high; yet, when we look at the amount of money spent on average per year over the last eight years (approximately USD 5,125,000), perhaps one year's worth of funding could have been disbursed among the 345 municipalities for an average amount of almost USD 15,000 per municipality to do an initial assessment prior to the intervention.…”

“…Yet, published data suggest that Chile differs markedly between regions in terms of dog ownership practices, such as the numbers of dogs that residents own, emphasizing the importance of understanding the human-canine dynamic before implementing new interventions. A lack of clarity about these dynamics and the ensuing problems on a site-by-site basis can result in programs with unclear objectives, ineffective interventions, or a lack of coordination from municipality to municipality [30,31].…”

Assessing the impact of free-roaming dog population management through systems modelling

“…System dynamics modelling allows complex and interactive systems to be explained and the impact of interventions on model behaviour to be evaluated [13,14] . Dog population dynamics have been investigated with both system dynamics approaches [15][16][17][18][19][20][21][22][23] and agent-based models [24,25] , assessing the effects of management strategies on population size [15,21,22,25,26] , euthanasia rates [23] , and disease dynamics [19,20] . Most previous studies have modelled dynamics within a single subset of the population (e.g.…”

Priorities for Research into the Impact of Canine Surgical Sterilisation Programmes for Free-Roaming Dogs: An International Priority Setting Partnership

“…Despite the widespread use of sterilisation for several decades in many countries around the world, there is limited published evidence demonstrating if these impacts are achieved [ 2 , 3 , 4 ]. The use of sterilisation in rabies control is particularly controversial, with recent modelling of different catch-neuter-vaccinate-release (CNVR) intensity scenarios in the field highlighting the potential difficulties in achieving rapid and sufficient dog vaccination coverage to control dog rabies [ 5 ]. The use of sterilisation in rabies control is also difficult to evaluate directly, although the potential benefits have been described [ 4 , 6 ].…”