Toxocara canis and Toxocara cati are known as common roundworm in dogs and cats, respectively. The objective of the current study was to determine the molecular prevalence and risk factors associated with T. canis and T. cati infections in stray dogs and cats, respectively, in Bangkok, Thailand. In total, 1000 fecal samples (from 500 dogs and 500 cats) were collected from stray dogs and cats residing in Bangkok temples. DNA was extracted and screened for T. canis and T. cati using polymerase chain reaction (PCR) with the internal transcribed spacer (ITS) region. The overall prevalence of T. canis in the stray dogs was 5.4% (27/500) and 0.6% (3/500) for T. cati in the stray cats. Toxocara canis infections were detected in stray dogs from 11 out of 48 districts (22.9%), with Bang Khen district having the highest proportion of infected dogs, whereas T. cati infections were only detected in the stray cats in Lat Krabang district. These results indicated that stray animals residing in Bangkok temples pose a considerable public health risk due to zoonotic parasites, especially T. canis.

Pet animals (dogs and cats) can be infected with several companion vector-borne pathogens (CVBPs). Morbidity and mortality have been reported in pet animals due to CVBP infections. Pet animals living in close proximity to humans are able to transmit zoonotic pathogens. This study used molecular techniques to investigate the prevalence of CVBPs in apparently healthy pet animals (dogs and cats) from Khukhot City Municipality, Pathum Thani province, Thailand. In total, 210 blood samples were randomly collected from 95 dogs and 115 cats for the detection of seven companion vector-borne pathogens (Anaplasma, Babesia, Bartonella, Ehrlichia, Hepatozoon, Mycoplasma, and Rickettsia) using polymerase chain reaction. The results showed that 10.5% (22/210) of apparently healthy pet animals were infected with at least one pathogen, comprising 6 dogs (6.3% of all dogs tested) and 16 cats (13.9% of all cats tested). Ehrlichia (6.3%) was present only in dogs; furthermore, 1.1% of the dogs were positive for Anaplasma. There was one dog case co-infected with two pathogens (1.1%). In cats, Mycoplasma (9.6%) was the predominant CVBP, followed by Rickettsia (4.4%). The DNA sequences of all positive animals were 97–99% homologous to those found in the GenBank™ database for all CVBPs identified, namely Ehrlichia canis, Anaplasma platys, Rickettsia felis, Mycoplasma haemofelis, and Candidatus Mycoplasma haemominutum. Additionally, the risk of infection with CVBPs in pets was significantly associated with age, with young dogs more likely to be infected with CVBPs than adult dogs (OR 8.5, 95% CI 1.4–50.1, p = 0.006), while adult cats were more likely to be infected with CVBPs than young cats (OR 3.8, 95% CI 1.0–14.0, p = 0.038). The detection of CVBPs demonstrated the potential risk of infection that may occur in apparently healthy pet animals in Pathum Thani province. These results confirmed that apparently healthy pet animals may still be at risk of vector-borne infections and could maintain the infection cycle in pet populations. Furthermore, sampling a greater number of apparently healthy pet animals may disclose predictors of CVBP positivity in domesticated animals in this area.