Horses, donkeys and mules share common parasites but the clinical response, such as diarrhea and poor body condition seen in some species with endoparasitism, is less common in donkeys and mules. Donkeys exhibit a higher prevalence of intestinal nematodes than horses and a greater resilience to clinical signs of infection. Common internal parasites are strongylids, from the subfamilies Strongylinae and Cyathostominae: Strongyles spp., Dictyocaulus arnfieldi, Oxyuris equi, Parascaris spp., and Anoplocephala spp. External parasites such as mosquitoes, ticks, lice, and flies affect the skin, suck blood and can transfer many pathogens. The survival and transmission of parasites are influenced by environmental conditions, social structures and population density, co-grazing between species, overuse of anthelmintics and overall management. Fecal egg count (FEC), serological tests, ELISA or PCR are diagnostic testing modalities used in the field of parasitology, along with microscopic analysis of skin scrapings to diagnose ectoparasite infestations. Good management includes grooming, the use of insect repellents, strategic deworming programs, and maintaining clean and dry environments. Commonly used anthelmintic drug classes in equids are benzimidazoles, tetrahydropyrimidines, macrocyclic lactones and praziquantel for internal parasites. Treatment used against ectoparasites include organophosphates, pyrethrin, pyrethroids, insect growth regulators, acid salt and biological control. Owners usually control parasites themselves which leads to errors in therapy, the use of incorrect doses, and inadequate selection or formulation of medicines. Parasitic resistance to drugs in horses is an emerging concern, leading to reduced efficacy of treatments. Plants or plant extracts can be used as therapeutic alternatives in antiparasitic treatment. Parasitology is comprised of the biology of both hosts and parasites, the interactions between them, and the pharmacokinetics of the drugs used to control them. The complexity of the field and the emerging threat of anthelminthic resistance make additional education of breeders, owners and veterinarians in all aspects of parasitology in horses, donkeys and mules. Advances in the scientific literature will be necessary to expand the knowledge of the pharmacokinetics, diagnostics, resistance and alternative treatments in the field of parasitology.