Impact Assessment of Free-Roaming Dog Population Management by CNVR in Greater Bangkok

Abstract

A high-intensity catch, neuter, vaccinate and return (CNVR) intervention was used over 5 years to manage the free-roaming dog population of Greater Bangkok, using nearly 300,000 CNVR operations across six provinces. An evaluation was conducted using multiple methods to assess the impact of this intervention, including clinical data, an observational street survey, an online attitude survey and reported cases of dog rabies confirmed with laboratory testing. The evaluation found evidence of a reduction in free-roaming dog density over time (24.7% reduction over 5 years), a reduction in dog rabies cases (average reduction of 5.7% rabies cases per month) and an improvement in dog-human relationships (a 39% increase per year in free-roaming dogs with visible signs of ownership or care and a perception of less trouble with free-roaming dogs in districts benefiting from CNVR). The CNVR intervention appears to have been effective at reducing the current free-roaming dog population and minimizing one future source of free-roaming dogs by limiting breeding of dogs accessible on the streets. However, there is evidence that other sources of free-roaming dogs exist, presumed to be predominately abandoned or lost owned dogs that were previously inaccessible to the CNVR intervention because they were ordinarily confined or living outside the project area. Hence, fully effective dog population management will require further interventions targeting owned dogs in addition to this CNVR effort.

Keywords: CNVR; catch; dog; dog population management; dog welfare; neuter; rabies; vaccinate and return.

Figure 1

Free-roaming dogs per km of street surveyed along 20 routes in 2016, 2020 and 2021 with exponential trendlines fitted for each route.

Figure 2

Predicted change in free-roaming dog counts over years as a percentage relative to the starting count in 2016, with varying levels of sterilisation rate and proportion of spays; mean and ±1 standard deviation.

Figure 3

Responses of residents living in ‘treatment’ districts and those living in ‘control’ districts to the question “thinking of the dogs on your Soi today—and then thinking back 4 years ago to 2016—which of the following statements is most true?”. Responses from people who had moved to the area recently or responded “I don’t know” are excluded.

Figure 4

Percentage of females showing signs of lactation in 2016, 2020 and 2021. Dashed lines indicate yearly means.

Figure 5

Percentage of observed dogs that are puppies (<6 months of age) in 2016, 2020 and 2021.

Figure 6

Relationship between the percentage of lactating females and the percentage of puppies in 2016, 2020 and 2021.

Figure 7

Dog rabies cases and the number of CNVR operations (sterilisation and vaccination) per month over the 5 years of the CNVR project.

Figure 8

Responses of residents to the question, “How accepting are you of the dogs on your street?”. Responses from people who had moved to the area recently or responded “I don’t know” are excluded.

Figure 9

Responses of residents to the question, “In the last month, have you been annoyed or troubled by a dog or dogs in your neighbourhood?” split by those living in ‘control’ districts and those living in ‘treatment’ districts.

Figure 10

Responses of residents to the question, “Thinking of the dogs on your Soi (street) today—and then thinking back 4 years ago to 2016—which of the following statements is most true?” split by those living in ‘control’ districts and those living in ‘treatment’ districts. Responses from people who had moved to the area recently or responded “I don’t know” are excluded.

Figure 11

Percentage of dogs with signs of ownership or care recorded on each of the routes used for the street surveys in 2016, 2020 and 2021. Dashed lines indicate yearly means.

Figure 12

Predicted change in free-roaming dog counts over years as a percentage relative to the starting count in 2016, with varying sterilisation rates and proportions of spays; mean and ±1 standard deviation.