Working equines in Mexico are distributed throughout the territory, but the management practices and the health and welfare conditions differ widely between regions depending on people's customs and specific climate conditions. The Eastern coast of México has an important equine population used for work in rural production systems. Something that owners and animal workers are concerned about is how the gastrointestinal parasite burden affects the equines nutritional status and health. This is because parasite reinfestations are most likely to occur in hot, humid climates. However, there are few reliable data to support this and the lack of information makes it difficult to design treating strategies and extension activities to ensure the health and welfare of equines in these areas. To address this, a trial was designed to determine the prevalence of animals infected with gastrointestinal nematodes, the parasite burdens and their effects on the nutritional status and haematological values of working equines from a tropical area of Mexico. One hundred and twelve equines were randomly selected in five different villages of the area. One sample of faeces and one sample of blood (in a tube containing EDTA) were obtained from every animal. Gastrointestinal parasite burden using the McMaster technique, proportions of nematodes species present through a coproculture, packed cell volume, total plasma proteins, red blood cell count and white blood cell count, were measured. The nutritional status was assessed using body condition score. Data was analysed using descriptive statistics. All calculations were done per species (horses, donkeys and mules) and community (1, 2, 3, 4, and 5). Prevalence of infected equines was higher than 90%. The most common nematode species was Strongylus vulgaris. The parasite burden was low to moderate in horses and donkeys, higher in mules; however, it did not affect the body condition, nor the haematological values (P>0.05). Results suggest that in spite of the high prevalence and parasite burdens, equines involved in this trial are not being seriously affected, as shown by the body condition and haematological parameters.
