Modeling the effect of surgical sterilization on owned dog population size in Villa de Tezontepec, Hidalgo, Mexico, using an individual-based computer simulation model

Abstract

Surgical sterilization programs for dogs have been proposed as interventions to control dog population size. Models can be used to help identify the long-term impact of reproduction control interventions for dogs. The objective of this study was to determine the projected impact of surgical sterilization interventions on the owned dog population size in Villa de Tezontepec, Hidalgo, Mexico. A stochastic, individual-based simulation model was constructed and parameterized using a combination of empirical data collected on the demographics of owned dogs in Villa de Tezontepec and data available from the peer-reviewed literature. Model outcomes were assessed using a 20-year time horizon. The model was used to examine: the effect of surgical sterilization strategies focused on: 1) dogs of any age and sex, 2) female dogs of any age, 3) young dogs (i.e., not yet reached sexual maturity) of any sex, and 4) young, female dogs. Model outcomes suggested that as surgical capacity increases from 21 to 84 surgeries/month, (8.6% to 34.5% annual sterilization) for dogs of any age, the mean dog population size after 20 years was reduced between 14% and 79% compared to the base case scenario (i.e. in the absence of intervention). Surgical sterilization interventions focused only on young dogs of any sex yielded greater reductions (81% - 90%) in the mean population size, depending on the level of surgical capacity. More focused sterilization targeted at female dogs of any age, resulted in reductions that were similar to focusing on mixed sex sterilization of only young dogs (82% - 92%). The greatest mean reduction in population size (90% - 91%) was associated with sterilization of only young, female dogs. Our model suggests that targeting sterilization to young females could enhance the efficacy of existing surgical dog population control interventions in this location, without investing extra resources.

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

“…Our results suggest that targeting efforts to reduce abandonment could be as important as directing efforts to reduce the birth rate or increase the removal rate. These findings are in line with those in previous modelling studies reporting synergistic effects of combined fertility control and restricted movement of owned dogs [26] , and emphasising the potential impact of owned dog abandonment dampening the effectiveness of CNR interventions [15,17,22] . Future dog population management efforts should aim to identify the sources of population increase (i.e.…”

“…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.…”

Dynamic modeling of female neutering interventions for free-roaming dog population management in an urban setting of southeastern Iran

“…In Mexico, the model developed by Kisiel et al offered that, regardless of dog age and sex, following 8.6–34.5% annual sterilization, the dog population size after 20 years was reduced between 14 and 79% compared to the absence of intervention. They concluded that sterilization of only young, female dogs has the greatest impact on population reduction of 90–91% 32 . Another study on owned dog population in Italy estimated that to stop population growth, a sterilization rate of > 55% is needed and concluded that only 26% sterilization of female young dogs is adequate to halt dog population growth.…”

“…Female dogs in reproductive age are central to any FRD population control program. Findings of a study performed in Mexico suggested that sterilization of young female dogs can enhance reductions in owned dog population size in a 20-year horizon, compared to the current sterilization strategy focused on dogs, regardless of age and sex 32 . Nonetheless little is known on the impact of sterilizing unowned female dogs population.…”

Current characteristics of animal rabies cases in Thailand and relevant risk factors identified by a spatial modeling approach

“…Stabilizing the number of free-roaming dogs, particularly in the endemic areas, should be strongly implemented, focusing on young, female dogs. A previous individual-based model strongly suggested that neutralizing only young, female dogs was the best population control strategy (reducing 90–91%) compared to targeting female dogs of any age or mixed-sex sterilization of only young dogs (reducing 82–92%) [ 51 ].…”