Domestic dog ecology, rabies vaccination, and predictors of dog ownership in Osun State, Nigeria

¹Nigeria Field Epidemiology and Laboratory Training Program, Abuja, Nigeria, ²Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan, Nigeria, ³Osun State Ministry of Agriculture and Food Security, Osun State, Nigeria, ⁴African Field Epidemiology Network, Abuja, Nigeria

^&Corresponding author
Oluseyi Adebayo Timothy Akano, Nigeria Field Epidemiology and Laboratory Training Program, Abuja, Nigeria

Introduction    

Domestic dogs are ubiquitously associated with human populations in nearly all parts of the world [1]. The domestic dog, a member of the genus Canis, otherwise referred to as canines, had being a close ally of humans for centuries and are believed to be the closest animal to man [2]. Dogs were used as security guards, as pets, as hunting dogs, for breeding, and herding [3]. They are also used for law enforcement to assist in detecting people that are being smuggled across international borders, detecting drugs, improvised explosive devices (IEDs), and other illegal substances. In the medical field, dogs are used to help people with disabilities. Dogs are being trained to aid in the diagnosis of diseases. The companionship that they provide is believed to foster healthier living in children, the elderly and those isolated by stigmatization due to diseases like AIDS [4]. However, they also serve as vector for several disease agents, chief among them being rabies disease [5]. To maximize the benefit of canine therefore, it is important to understand their ecological distribution and health status, especially as it relates to rabies vaccination.

Reliable estimates of global dog population are not available; however, researchers have reported varying population estimates in different regions and parts of the world. In general, dog-to-human ratio of one to ten (1:10) to one to six (1:6) has been reported in the American and European countries [6]. In Mexico, dog-to-human population ratio of 1:1.7 and 1:4.6 were reported in different rural communities and 1:3.4 in a city [7], 35.6% of households in Ireland have one or more pet dogs [7,8]. In Africa, reported dog-to-human population ratios vary widely, ranging from 1:3.7 to 1:47. Ratio of 1:47 in Uganda, 1:14 in Tanzania, 1:7.7 in Machakos District of Kenya, 1:6.5 in Zimbabwe, 1:4.5 in Madagascar at different times [1,9-13]. In Nigeria however, reported dog-to-human population range between 1:3.7 and 1:25. Researchers reported 1:11 of owned dog-to-human population and 1:25 stray dog-to-human in Oyo State, 1:13 dog-to-household in Kwara State, dog-to-human ratio of 1:4.1 in Bauchi and Borno States, 1:4 in Plateau and Benue States and ratio of 1:3.7 in the Federal Capital Territory [14-20]. In Southwest Nigeria, ratio 1:11 of owned dog-to-human population and 1:25 stray dog-to-human in Ibadan, Oyo State was further reported [14].

A study on knowledge, attitude and practice about rabies prevention and control conducted in Tanzania revealed that only 51% of respondents vaccinated their dogs against rabies while rabies vaccination coverage survey in six selected villages in Tanzania as at 2012 was estimated at 25% [21,22]. In Uganda as at 2003, rabies vaccination coverage of 36.1% was reported [9]. In a study conducted in Benue State, Nigeria, dog owners reported 26.4% rabies vaccination coverage [16]. This level is grossly insufficient to prevent rabies transmission compared to the recommended minimum herd coverage of 70% [15,23,24]. In Osun State however, no published or unpublished document on dog population, demography or ecology was found. We, therefore, determined demographic characteristics, rabies vaccination coverage and predictor of dog ownership in Osun State to provide information for the development of effective dog management and rabies vaccination measures as well as providing baseline for future researches.

Methods     

Study area: the study was carried out between March and May 2019 in Osun State, Nigeria. The State is an inland state in south-western Nigeria, situated within the tropical rain forest zone of Nigeria with patches of savannah in the northern part of the state. Politically, the state is divided into three Senatorial Districts with 30 Local Government Areas (LGAs), Osogbo being the state capital. The estimated population of the state as at 2019, using the reported annual growth rate of 3.25%, is 5,178,578 [25]. The state comprises one main ethnic group, Yoruba, with major sub-ethnic groups being, Ijesha, Oyo, Ibolo, and Igbomina. Religions practiced were Islam, Christianity and traditional faith. Animal health services in the state are under the Ministry of Agriculture and Food Security which among other roles is saddled with the development and implementation of government policies regarding animal health. The ministry has veterinary clinics in about 16 LGAs manned by qualified veterinary doctors or at least an animal health technologist as zonal veterinary Officers. Most of the clinics are organized to provide veterinary services to a neighboring LGA either through ambulatory posts or outreaches. Complementing the services are the private veterinary practitioners providing preventive, control and curative veterinary services in the state.

Study design and eligibility criteria: a cross-sectional study design was conducted to determine demographic characteristics, rabies vaccination coverage and dog ownership predictors using an adapted standard questionnaire [6]. The survey was conducted between March and April, 2019.

Inclusion criteria: any persons above the age of 18 years residing in the selected household were included as respondents in the study.

Exclusion criteria: any persons in the inclusion criteria with visual or auditory impairment(s), mental illness or who had not resided in the household for more than six months were excluded.

Sampling technique: multi-stage sampling technique was adopted. Household sample size was determined by the formula described by Thrusfield [26]. Eleven LGAs were randomly selected using a simple random technique. Thereafter, three wards per LGA selected using simple random sampling technique. At the Ward stage, three streets per ward were selected using systematic random sampling technique followed by three to four households´ selection per selected street using simple random sampling technique to make the required households sample size. At the final stage, one occupant per household, residing in the selected households not younger than 18 years old, was randomly selected as respondent.

Sample size determination: the sample size was calculated using the formula as described by Thrusfield [26]. Using 24% proportion (P) as reported in a similar study conducted in Tanzania on dog ownership [1] and precision (d) of 5%, the effective sample size (ne) was calculated to be 281 households using the single proportion population formula, given as;

Study instruments and data collection methods: a pretested standard structured questionnaire by WHO/WSPA was adapted for the study [6], using electronic data management tool (Kobotool) for data collection to estimate owned dog population. Household and dog-level data was obtained from selected member of the household. The data included the number of people in the household, household demographic characteristics, number of dogs per household and individual dog demographic information and vaccination history. Dependent variable being dog ownership with all other variables as independent. Fifteen (15) interviewers were recruited from Osun State Ministry of Agriculture and Food Security, comprising mainly university graduates with experience in data collection. They were trained on interview techniques to minimize bias and the use of electronic data collection tool (Kobo Collect Application) for data collection. Location of the selected households was also captured using GPS.

Data analysis: data collected were analyzed using Microsoft Excel 2013 and Epi Info 7. Univariate analyses to determine means, range, frequencies, and proportions of all the variables generated to describe dog ecology and vaccination coverage. Bivariate analyses using Chi square and Fisher exact tests were carried out to determine association between owning a dog as the dependent variable and all others as independent variables. Confidence limit was set at 95% and p-value <0.05 was considered significant. Variables that were significant at bivariate analyses were fitted into multivariate logistic regression analyses model using backward stepwise approach. Any p-value less than 0.05 were considered statistically significant. We estimated owned dog population by multiplying dog to human ratio by 2019 projected human population in the state based on National Population Commission Census figures. The number of dogs found during the household survey was divided by the corresponding human population obtained during the survey; dog to human ratio was calculated [6,27,28]. Dog-to-household ratio was calculated by dividing the number of dogs found during the survey by the total number of households that responded to the questionnaire.

Ethical approval: this study was approved by the Animal research ethics committee of Osun State Ministry of Agriculture and Food Security (Ref. no: VD.19/597/76). Informed consent was obtained from all participants before proceeding to questionnaire administration.

Study limitations: this study was subject to recall bias, and social desirability bias and misinformation bias. Recall bias was minimized by the use of pretested standard structured questionnaire adapted for the study. Social desirability and misinformation bias which is also associated with surveys was minimized by training the interviewers on questioning techniques and evidence-based conclusions.

Results     

A total of 320 households were visited for the survey, 18 declined consents, giving a non-response rate of 5.6%. The selected households with approved consent spread across 11 LGAs giving a good spread (Figure 1). An aggregate of 57 (18.9%) of 302 sampled households owned at least a dog. Household setting comprised mostly 71.5% rural while traditional single-family type of home constituted 50.3% of homes surveyed. There was no perimeter fencing in 254 (84.1%) households. More than 75% of dogs were local breeds with 53.8% of all dogs being female. Age range 13 to 24 months old accounted for the highest (30.2%) proportion, canine rabies vaccination coverage in the state was 30.2% (55 of 182), with 53.2% in the urban and 11.1% in the rural households (Table 1). Dog-to-human population ratio in the state was 1:10.7 while dog-to-household ratio was calculated to be 1:1.7 as presented in Table 2. A total of 486,076 domestic dogs were estimated to be the total domestic dog population in Osun State, Nigeria (Table 2).

More than two-thirds (70.8%) of the respondents mentioned religion as a reason for not owning a dog (Table 3). At bivariate analyses, urban home setting (OR=3.1; CI 1.7- 5.7), presence of children in the household (OR=5; CI 1.5 - 16.5), sex of the head of household being male (OR=2.8; CI 1.3 - 5.8), home enclosure with the presence of a fence (OR=5.3; CI 2.7 - 10.3), complete restriction of dog movement with fence (OR=4; CI 1.8 - 8.7) and occupation of the head of household being hunting (OR=3.5; CI 1.2 - 10.5) were all statistically significant (Table 4). However, multivariate analysis revealed that urban home setting (AOR=3.5; CI 1.6-7.7), presence of children in the household (AOR=8.7; CI 2.2 - 34.0) and the head of household being a hunter (AOR=4.5; CI 1.4 - 14.6) were the independent predictors of dog ownership (Table 5).

Discussion     

Traditional single-family type of home constituted about half of all the homes surveyed and there were perimeters fencing in only about a-fifth of all the households. These type of homes suggest a rural to semi-urban community which describes Osun State [29]. Heads of households were about 70% males as expected in a rural to semi-urban communities like Osun. The finding that trading and farming were the most frequent occupation of the respondents may still be pointing towards a rural to semi-urban community settings with little formal employment characteristics. Domestic dog sex ratio of almost 50% found in this study contrasts a study conducted in urban and rural areas of Borno State that reported male dog to female ratio of about 1 to 2 and 4 to 1 [17]. The variation may have been influenced by the different technique adopted, or that true demographic variation exists in these states due to differences in cultural and traditional practices. The finding that the age-range 13 to 24 months old accounted the highest (30%) proportion of dogs in the state may suggest puppyhood death due to vaccine-preventable diseases as vaccination coverage is low. Local breeds of dogs were about three-quarter of all dogs in the state which may suggest that most dog owners in the state were not willing to invest huge amount which is required for the purchase and maintenance of foreign breeds. We estimated 2019 owned dog population in Osun State to be a little less than half a million with higher proportion of unrestricted or stray dogs reported in urban home settings which suggests that the dogs were drawn to urban settings due to availability of consumable wastes compared to rural settings with the low chances of finding food. World Organization for Animal Health (OIE) proposed identifying source of unrestricted or stray dog as one important consideration for effective dog population management [30].

The dog-to-human ratios of about 10% gotten is lower compared to about 25% estimates in Federal Capital Territory, Bauchi, and Borno States [16,17,20]. However, the study in Bauchi State estimated both street and household counts while the study in Borno State and Federal Capital Territory estimated the ratio for urban/semi-urban areas only. Also, local attitudinal and cultural practices of these other states vary from that in Osun State. These may have accounted for the varied ratio as revealed in this study coupled with temporal and spatial differences of the studies. Also, about 8% household owning at least a dogs reported in Kwara State [15] is much lower compared to ratio gotten in this study, which may be as a result of different techniques adopted or that a real difference actually exist. While we adopted questionnaire survey, the other study adopted aerial photograph enhanced dog census. Only about one-third of the dogs were vaccinated against rabies in the state with about 50% coverage in the urban areas. This is similar to what was reported in Abuja, Nigeria [20].

In this study, living in urban home setting, presence of children in the household and head of household being a hunter were independently associated with owning a dog. A study found sex of the head of the household being male; if they owned a cat; or if they owned poultry to be associated with dog ownership [1], but this study showed that, though sex of the head of the household had association with dog ownership, it was most likely a confounder. However, the findings of our study is in tandem with the study that found that “presence of children in the household” had true association with dog ownership [31].

Conclusion     

An estimate of 486,076 owned dogs’ lives in Osun State as at the time of study with a ratio of one dog per about eleven persons. Rabies vaccination coverage in Osun State was very low (30%) compared to recommended minimum coverage for herd immunity. Households situated in the urban areas or with a hunter as household head or having children in the household are independently likely to own at least a dog in the state. We recommend that Veterinary authorities in Osun State Ministry of Agriculture and Food Security develops a comprehensive plan to improve dog rabies vaccination coverage, as stipulated by WHO, GARC and OIE to promote responsible dog ownership. To achieve the minimum recommended rabies vaccination coverage of 70% by 2030 [23], increased awareness and sensitization needs to be heightened, especially targeting hunters’ associations, schools and rural area dwellers.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

OATA, OOI and BOO developed the concept, OATA and JAT coordinated data collection, OATA. designed the questionnaire, performed the statistical analyses and developed the first draft. FS helped in conforming the manuscript to PAMJ format. All authors listed read, reviewed and approved the manuscript, agreeing that its content may be readily and freely available to any scientist wishing to use them for non-commercial purposes.

Acknowledgments     

I wish to acknowledge the effort and co-operation of staffs and principal officers of the department of veterinary services, Ministry of Animal Health and Food Security, Osun State and the Nigeria Field Epidemiology and Laboratory Training Program for their support and contributions in this research.

Tables and figure     

Table 1: ecology and demographic characteristics of owned-dogs and rabies vaccination coverage in Osun State, Nigeria

Table 2: estimates of dogs; households and dogs; human-population ratios in Osun State, Nigeria

Table 3: factors associated with non-owning a dog in Osun state, Nigeria

Table 4: association of socio-demographic characteristics with dog ownership in Osun State, Nigeria

Table 5: predictors of dog ownership in Osun State, Nigeria

Figure 1: selected LGAs and households for dog ecology study in Osun State, Nigeria

References