A survey in a major Mexican city (Merida) and three rural communities was conducted to generate information regarding the size and structure of the owned-dog populations and people's opinions about the dogs and how they took care of them. Household characteristics and dog population size, health and reproductive issues were compared between the two kinds of communities: urban and rural. A telephone survey was conducted in Merida city whereas personal interviews were used in the rural communities. Local veterinarians were also interviewed to evaluate their influence on the dog populations in Merida city. The ratio of people to dogs was 3.4:1 in the city, and 1.7:1 to 4.6:1 in the different rural communities. In general it was more common to find a dog-owning household in the city of Merida (72.8%) than in the rural areas (63.6%, 65.5% and 71.1%), and in the city more households had adequate fences to restrain dogs. Larger families were more likely to own a dog than small families. Households of med...

It's a dog's life: Canine transmissible venereal tumor is one of the few cancer lineages that is transferred among individuals through contact. It arose millennia ago and has been evolving independently from its hosts ever since. Baez-Ortega et al. looked at the phylogenetic history of the cancer and describe several distinctive mutational patterns (see the Perspective by Maley and Shibata). Most notably, both positive and negative selection show only weak or distant signals. This suggests that the main driver of the lineage's evolution is neutral genetic drift. Understanding the influence of drift may reshape how we think about long-term cancer evolution. Science , this issue p. eaau9923 ; see also p. 440

To assess the risk of zoonotic pathogen transmission as function of stray dog presence and health status, a cross-sectional study was carried out in a large city of southern Mexico that lacks comprehensive strategies for the control of stray canine populations. The photographic capture-recapture method was used to estimate the density of dogs/km². In the same way, dog feces from 14 public parks of the city were collected to determine the prevalence and intensity of infection with gastrointestinal parasites. The canine population was estimated between 65 and 80 thousand dogs, with a population density of 1,081 dogs/km², mostly males (71.4%). A high proportion of dogs (72.3%) were found to be in good body condition score (BCS 3). The person:dog ratio was 2.3. The likelihood of being in the BCS 2 category was lower in areas with a higher density of dogs. All feces collected from the parks contained eggs of intestinal parasites, most of them with a medium (42.9%) to high (35.7%) infection intensity, notably Ancylostoma caninum. It was recorded that cases with a low-intensity of GI infection showed polyparasitism (35.7%) associated with A. caninum. There is a large population of stray dogs that roam freely in the streets of Campeche city with access to sources of food, which is reflected by their good BCS, and dogs do not have access to preventive medicine programs (de-worming) and thus contaminate public parks with feces with significant parasitic egg loads of zoonotic importance.

The aim of this study was to determine the prevalence and risk factors associated withToxoplasma gondiiinfection in domestic cats using an indirect-ELISA (IgM and IgG) and PCR. Samples collected from 220 cats from Merida, Yucatan, Mexico, were analyzed. Cases were reported as acute or chronic. Cases when positive to IgM and IgG and PCR were considered as reactivated chronic infection. Risk factors (sex, age, body condition, diet access to hunting, and number of cats in home) were assessed with a multivariate analysis, 75.5% (166/220) of the cats were IgM and 91.8% (202/220) IgG-seropositive and 79% were PCR-positive (173/220). Number of cats per household and low body condition score were associated with reactivated chronic infection (). It is concluded thatT. gondiiis scattered in the studied population with several periods of reinfection, and therefore an environmental contamination with infecting oocysts exists and there are intrinsic associated factors in cats that increase the risk of becoming infected.