The population dynamics of horses refers to the study of changes in horse populations over time, influenced by factors such as birth rates, death rates, immigration, and emigration. These dynamics are shaped by environmental conditions, resource availability, predation, and human intervention. Understanding population dynamics is essential for managing wild horse populations and ensuring sustainable practices in breeding and conservation efforts. This page compiles peer-reviewed research studies and scholarly articles that explore the factors affecting horse population dynamics, including genetic diversity, habitat utilization, and the impact of management strategies on population stability and growth.
Berger J, Kock M, Cunningham C, Dodson N.Twenty-three (9 male, 14 female) wild horses (Equus caballus) in the Great Basin Desert were immobilized by ground techniques with succinylcholine chloride during 1,950 person-hr. Induction (means = 2.09 +/- 0.59 min) and recovery (means = 12.4 +/- 5.0 min) were rapid and most animals were returned in less than 10 min to original bands. Dosages ranged from 0.66-0.77 mg/kg body weight and neither abortions nor band changes in group membership resulted. However, a few concerted efforts up to 24 hr were needed to return some animals to original bands and three non-drug related mortalities occurre...
Science (New York, N.Y.)June 24, 1983
Volume 220, Issue 4604 1403-1404 doi: 10.1126/science.220.4604.1403
Berger J.The identities, sexes, and reproductive status of groups of wild horses (Equus caballus) living in the Great Basin Desert of North America were known prior to their deaths on ridgelines. Another group of very young horses died on a quagmire. Snow accumulation or drought was apparently responsible for the mass deaths. These data have implications for reconstructing some aspects of the social structure of fossil mammals on the basis of skewed sex or age ratios in bone assemblages.
Berger J.Much evidence now suggests that the postnatal killing of young in primates and carnivores, and induced abortions in some rodents, are evolved traits exerting strong selective pressures on adult male and female behaviour. Among ungulates it is perplexing that either no species have developed convergent tactics or that these behaviours are not reported, especially as ungulates have social systems similar to those of members of the above groups. Only in captive horses (Equus caballus) has infant killing been reported. It has been estimated that 40,000 wild horses live in remote areas of the Great...
Chay S, Woods WE, Rowse K, Nugent TE, Blake JW, Tobin T.Studies were undertaken to determine blood levels of furosemide in horses after 0.5- and 1.0-mg/kg doses administered iv. Analyses indicated that the pharmacokinetic parameters were dose independent and best described by a three-compartment open model. The alpha-, beta-, and gamma-phase half-lives of 5.6, 22.3, and 158.5 min, respectively, were observed after the 0.5-mg/kg dose. Similarly, the respective half-lives after the 1.0-mg/kg dose were 5.8, 24.1, and 177.2 min. After a 0.5-mg/kg dose of furosemide, population frequency distributions were evaluated at 1 hr and 4 hr post-drug administra...
Bailey E.336 Standardbred mares and 334 Thoroughbred mares in the vicinity of Lexington, Kentucky, were lymphocyte typed for 11 allelic antigenic specificities of the equine lymphocyte antigen (ELA) system. The Standardbred mares were divided into a population of pacers and a population of trotters. Substantial differences in ELA gene frequencies were found between the 3 groups. When the distribution of antigens within populations were compared to Hardy-Weinberg equilibrium expectations, relatively good agreement was found.
Bailey E.The linkage group formed by the ELA and A blood group system in horses was studied in American Standardbred horses. The distance between the ELA locus and the A blood group locus was measured as 1.61 centimorgans, observing only the haplotypes contributed by the sires. Strong linkage disequilibrium was found in pacing Standardbred horses for ELA-W1 with Aa, ELA-W5 with Ab and ELA-W10 with Ab. Linkage disequilibrium was apparent at both the population and family level. Among trotting Standardbred horses, linkage disequilibrium was found for ELA-W1 with Aa and for ELA-W10 with Ab. It was not pos...
Klingel H.The basic social unit in feral horses is the family group consisting of one stallion, one to a few unrelated mares and their foals. Surplus stallions associate in bachelor groups. Stallions are instrumental in bringing mares together in a unit which then persists even without a stallion. The similarity of social organization in populations living in a variety of different habitats indicates that feral horses have reverted to the habits of their wild ancestors, and that domestication has had no influence on this basic behavioural feature.
Hatami-Monazah H, Pandit RV.The group of Caspian ponies studied contained some animals with 65 chromosomes and others with 64 chromosomes. The morphology and G-banding pattern of the chromosomes resembled those of Equus caballus and E. przewalskii. The karyogram of animals with 65 chromosomes was identical to that of the cross between E. caballus and E. przewalskii. It is suggested that the Caspian pony is the product of natural hybridization between E. caballus and E. prezwalskii. Low reproductive effeciency of the Caspian pony is suggested as the cause of decline in the population of these animals.
English AW.The anterior mesenteric arteries of 138 horses slaughtered in southern Queensland were examined for the presence of S. vulgaris larvae. Seasonal differences were noted in the size of arterial populations of this parasite, with higher mean monthly numbers of worms per horse occurring in winter. There was an equally high incidence of severe verminous arteritis during the winter months of June, July and August, compared to arteries examined during the warmer months, when there were smaller numbers of larvae. It was concluded that more infective larvae were available on pasture during the warmer m...
Wilson RT.Equines have been largely ignored in modern scientific literature on domestic animals, probably because they are not providers of meat and milk. Their contribution to the economy in the Sudan, however, is considerable and they are the principal means of transport both as baggage and as riding animals. They also play an important role in the supply of fuel and the distribution of domestic water in the larger villages and towns. Information on population structure is provided and descriptions, with particular reference to withers height and weight, are given of two types of donkey and of the hor...
Kaminski M.The detection of the recessive null allele of horse serum esterase (Es) is possible in heterozygotes Es+/EsO which by starch gel electrophoresis appear like homozygotes Es+/Es+. Two methods are proposed, the titration of enzymatic activity of esterase and the immunochemical titration of esterase as antigen. These methods can be applied to solve the cases of suspect parentage or in population studies.
Ricketts SW, Rossdale PD.The authors discuss the value of a practice laboratory to the equine clinician and its priorities. Laboratory examinations of particular value are described in relation to their clinical application. The need to establish normal values according to laboratory and horse population is stressed. Tables of normal parameters related to age groups of horses in the authors' practice are presented.
Feist JD, McCullough DR.A behavioural study of feral horses was conducted on the Pryor Mountain Wild Horse Range in the western United States. All 270 horses on the Range were identified individually. The sex ratio was nearly balanced. Foal to adult female ratio was 43-2:100. Morality was concentrated among foals and old horses. Horses were organized as forty-four harem groups each with a dominant stallion, one to two immature stallions, one to three immature mares, one to three adult mares and their yearling and foal offspring, and 23 bachelor groups of one to eight stallions. Harem groups were quite stable year-rou...
Hesselholt M.By means of isoimmunizations and heteroimmunizations 10 equine blood typing reagents were isolated. The specific antibodies were complete agglutinins, which were used in the direct agglutination test in saline medium. The reagents were designated A2, C, D, E, G, H, I, K, Da1, and Da2 reagent. Da1 and Da2 are preliminary designations. The data obtained from blood typing of a family material and a population material of Icelandic horses showed that the occurrence of each blood type factor is controlled by a single, dominant gene. The family data tended to show that the blood factors under invest...
Feral horses in Theodore Roosevelt National Park (TRNP) represent an iconic era of the North Dakota Badlands. Their uncertain history raises management questions regarding origins, genetic diversity, and long-term genetic viability. Hair samples with follicles were collected from 196 horses in the Park and used to sequence the control region of mitochondrial DNA (mtDNA) and to profile 12 autosomal short tandem repeat (STR) markers. Three mtDNA haplotypes found in the TRNP horses belonged to haplogroups L and B. The control region variation was low with haplotype diversity of 0.5271, nucleotide...
Two closed horse herds (Old Lot 4 and Field 24), infected since 1966 with Population B small strongyles resistant to thiabendazole (TBZ) and phenothiazine (PTZ), were terminated in February, March, and May, 2005. At necropsy, only the large endoparasites were identified and counted. The number of horses on pasture was 14 (239 days of age to 23 years old) for Old Lot 4 and two (3 to 20 years old) for Field 24. The time of the last antiparasitic treatment, relative to the year (2005) of necropsy, was 26 years for Old Lot 4 and 9 years for Field 24 horses. Gasterophilus intestinalis third instars...
A breed known for its versatility, the American Quarter Horse (QH), is increasingly bred for performance in specific disciplines. The impact of selective breeding on the diversity and structure of the QH breed was evaluated using pedigree analysis and genome-wide SNP data from horses representing 6 performance groups (halter, western pleasure, reining, working cow, cutting, and racing). Genotype data (36 037 single nucleotide polymorphisms [SNPs]) from 36 Thoroughbreds were also evaluated with those from the 132 performing QHs to evaluate the Thoroughbred's influence on QH diversity. Results s...
Pepper B, North E, Culwell J, Nicodemus MC, Cavinder C, Harvey K, Williams T.Due to the incorporation of the Golden American Saddlebred Horse Association (GASHA) into the American Saddlebred Horse and Breeders Association (ASHBA), breeding for coat color has become more challenging for horse breeders. However, with this merger, pedigree tracing can be of value in pinpointing foundation bloodlines within the GASHA that influence production of the golden coat phenotype. Objective: The study objective was to document the historical origins of the GASHA through pedigree tracing to determine the influence of dilution alleles that produce the golden coat phenotype. Methods: ...
Sharma M, Singh A, Kumar V, Olla N, Arora R, Sharma R, Mohan NH, Ahlawat S.The genus Equus, encompassing horses, donkeys, and extinct relatives, has evolved over approximately 55 million years from small, multi-toed ancestors to the modern horse. Selective breeding has produced over 600 distinct horse breeds optimized for diverse traits such as size, conformation, performance, and adaptability. In the past two decades, rapid advances in equine genomics have significantly deepened our understanding of the molecular basis of these traits. The integration of high-throughput sequencing, genome-wide association studies (GWAS), and single-nucleotide polymorphism (SNP) geno...
Saldaña CL, Justo S, Murga L, Vásquez HV, Maicelo JL, Arbizu CI, Bardales W.The complete mitochondrial genome of the Peruvian Paso Horse was assembled using PacBio HiFi long reads, resulting in a high-quality circular genome of 16,617 bp comprising 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a control region. Nucleotide composition and gene structure were consistent with other equine mitogenomes. Codon usage analysis revealed a bias toward CUA (Leu), AUA and AUC (Ile), suggesting translational optimization. Thirty-five heteroplasmic variants were identified, predominantly located in RNA genes (12 S rRNA and tRNA-Phe), with allele frequencies between 0.10 and 0.6...
Raftery AG, Gummery L, Garcia K, Mohite D, Capewell P, Sutton D.Equine trypanosomiasis is a neglected protozoal disease. Objective: To answer the study question: In equines what are the effects of disease management of trypanosomiasis on disease severity (individual level) and disease prevalence (population level) compared to no intervention? Methods: Systematic review. Methods: Studies were identified that described management of naturally occurring equine trypanosomiasis in any country following 'Preferred Reporting Items for Systematic Reviews and Meta-analyses' using eight international databases (1980-2022). Risk of bias was assessed using ROBINS-I. D...
Jlassi M, Dhifalli I, Ouled Ahmed H, Lasfar F, El Gtari M, Jemmali B.The genetic diversity and population structure of Tunisian Arabian horses were assessed using highly polymorphic microsatellite markers, which are critical for conservation and breeding programs. Despite the cultural and economic importance of Arabian horses in Tunisia, molecular data supporting their management remain limited. In this study, DNA from 130 horses was genotyped with 17 ISAG-FAO-recommended microsatellites to evaluate diversity within Eastern and Western Arabian lineages and their relationship to Thoroughbreds. Eastern Arabians showed an average of 5.176 alleles per locus, observ...
Stefaniuk-Szmukier M, Błaszczak A, Długosz B, Musiał A, Ropka-Molik K.The Silesian horse is a heavy warmblood breed developed in Polish Silesia through the covering of local mares by East Frisian and Oldenburg stallions. Because of its historical significance and genetic heritage, the breed is part of a conservation programme in Poland. One of the genetic disorders of concern in warmblood horses is fragile foal syndrome (FFS), an autosomal recessive disease caused by a mutation in the gene (c.2032G>A). Affected foals either perish in late pregnancy or are born with severe connective tissue abnormalities, leading to early death. As carriers do not exhibit sympto...
Ryder E, Given J, Hamilton N.Prohibited gene editing in horses (either in embryos or via cell culture and cloning) can result in both desired and undesired outcomes. If left undetected, changes can proliferate within the population in subsequent generations, posing a major threat to welfare and breed integrity.
Lewczuk D, Borowska A, Maśko M, Bagnicka E.: Knowledge of the genetic background of evaluated traits has been the basis for genetic progress in every horse-breeding population and is essential for precise breeding and up-to-date decision-making. The study aimed to estimate the heritability coefficients for field performance traits in mares. : The research was based on 1408 evaluations of mares conducted during the years 2002-2021 in 51 training centers in Poland. The preliminary analyses of the effects, significant for the investigated traits, were obtained using analysis of variance, and these additional data are also presented (SAS p...
Sharif MB, Mohaseb AF, Orlando L, Saliari K, Kunst GK, Czeika S, Mashkour M, Cucchi T, Peters J, Trixl S, Mohandesan E.The Roman conquest of the northern Alpine foreland in 15 BCE introduced larger-sized horses and hybrid mules to the region. To investigate their genetic profiles and influence on local breeding, we analyzed our previously generated shallow shotgun DNA data from 402 Late Iron Age and Roman equids, supplemented with mitochondrial and nuclear capture data from 40 to 31 equids from the same regions and periods. Late Iron Age and Roman horses exhibit high matrilineal diversity, with unique haplogroups in the latter indicating exogenous animals. The preferred use of male mounts in army service menti...
Maeda T, Inoue S, Ringhofer M, Hirata S, Yamamoto S.Encounters between competitive individuals or groups are common in social animals and can involve costly aggression; thus, animals often employ strategies to minimize direct conflict. However, research on whether and how animals adjust their group spatial structure when they encounter or spatially co-occur with a different group remains limited. We investigated how non-territorial units in feral horse multilevel societies manage spatial encounters with neighbouring units. We observed 25 reproductive units in northern Portugal, using drones, and employed statistical analyses to quantify spatial...
Bostal F, Scorolli AL, Zalba SM.Social conflicts surrounding invasive alien species can hinder their management, which makes studying the human dimension increasingly important. This approach is particularly relevant in natural reserves, where assessing visitors' perceptions of invasive alien species can help guide the design of more effective outreach and engagement strategies. This study examines visitors' knowledge of feral horses, their perceptions of these animals' value and ecological impact, and their acceptance of different management alternatives in a protected grassland area in the Argentine Pampas. We expect that ...
White SC, Thomas J, Shores C, Zimmerman K.Feral horses () have established large populations in west-central British Columbia (BC), Canada, where they overlap with native ungulates, including a declining woodland caribou () herd. In addition, feral horses co-occur with large carnivore species including wolf () and cougar (). Feral horses may act as a resource subsidy for predators, potentially altering predator-prey dynamics, yet empirical observations of predator interactions with feral horses are scarce in Canada. Between 2019 and 2025, we documented 21 instances of wolf predation or scavenging of feral horses, including one direct ...
Williams JM, Jordan S, Friend L, Kay E, Edmunds M, Flynn H, Wensley S.Horse welfare within/after racing is often questioned by the public. British Racing's Horse Welfare Board's "A life well-lived" strategy provides a blueprint for Thoroughbred welfare, advocating accurate lifetime traceability of horses as essential to achieve this. The Census aimed to establish a population density model for British Thoroughbreds, not actively engaged in racing. Equestrians who owned/kept a Thoroughbred were asked to complete the Census between May and December 2023. Frequency analysis identified patterns in passport compliance, knowledge and understanding of current systems, ...
Gholmohammadi S, Malekifard F, Yakhchali M.Ticks are important ectoparasites in equids, causing economic losses in animal husbandry in Iran and worldwide. This study was aimed to determine frequency and species diversity of hard ticks in equids in Ardabil province, during the four seasons in 2021. A total of 240 equids (187 horses, 53 donkeys) were randomly selected and examined. Ixodid ticks were collected from body surface of examined animals and identified. Of all examined equids, 32.5% horses, and 4.58% donkeys were infested with a total number of 412 ixodid ticks. Tick indices (tick number per animal) were 4.62. There was signific...
Taylor WTT, Delsol N, Oelze VM, Mitchell P, Stricker L, Lavin M, Ogundiran A, Hosek L, Barrón-Ortiz CI, Ojediran O, Quintero-Bisono D....Domestic equids were central to the initial colonization of the Atlantic coast of the Americas, a process partially chronicled by historical records. While Spanish colonists brought horses to the Caribbean decades earlier, settlement of the English colony at Jamestown, Virginia, was among the first dispersals of horses to the eastern seaboard. Archaeozoological analysis of identifiable domestic equid remains from two contexts associated with the initial occupation of Jamestown demonstrates intense processing and consumption of the first Jamestown horses during the "Starving Time" winter of 160...
Molazadeh S, Tukmechi A, Hadian M, Dalir-Naghadeh B.This study aimed to determine the prevalence and phylogenetic analysis of Ehrlichia spp. in horses and dogs in Iran. Blood samples were collected from 400 animals, including 200 horses and 200 dogs, from five different provinces in Iran. Polymerase chain reaction (PCR) was used to detect Ehrlichia spp. based on amplification of the 16S rRNA gene. The semi-nested PCR method was used to amplify the dsb, TRP36, and gltA genes. The results showed that 4.5 % of the samples (3 % horses and 6 % dogs) were positive for Ehrlichia sp. The highest prevalence was observed in Kerman and Khuzestan, while th...
The extremely rich palaeontological record of the horse family, also known as equids, has provided many examples of macroevolutionary change over the last ~55 Mya. This family is also one of the most documented at the palaeogenomic level, with hundreds of ancient genomes sequenced. While these data have advanced understanding of the domestication history of horses and donkeys, the palaeogenomic record of other equids remains limited. In this study, we have generated genome-wide data for 25 ancient equid specimens spanning over 44 Ky and spread across Anatolia, the Caucasus, Central Asia and Mo...
Koehler G, McNeill G, Hobson KA.We investigated the stable isotope hydrology of Sable Island, Nova Scotia, Canada over a five year period from September, 2017 to August, 2022. The H and O values of integrated monthly precipitation were weakly seasonal and ranged from -66 to -15 ‰ and from -9.7 to -1.9 ‰, respectively. Fitting these monthly precipitation data resulted in a local meteoric water line (LMWL) defined by: H = 7.22 ± 0.21 · O + 7.50 ± 1.22 ‰. Amount-weighted annual precipitation had H and O values of -36 ± 11 ‰ and -6.1 ± 1.4 ‰, respectively. Deep groundwater had mor...
Dash SK, Panda S, Karna DK, Mishra C, Kalaignazhal G.The present study aimed to identify significant morphometric traits in Malkangiri ponies of Odisha through principal component analysis. The data were collected randomly from 200 ponies aged more than five years and 13 morphometric traits alongwith three indices were recorded. The mean height at wither, height at croup, body length, chest girth, punch girth, height at forearm, height at hock, fetlock to coronet, chest width, neck circumference, poll to wither, wither to croup and croup to head of the tail were 126.7 ± 0.39, 122.6 ± 0.29, 107.9 ± 0.2, 122 ± 0.31, 118.6 ±â...
Błaszczak A, Stefaniuk-Szmukier M, Długosz B, Musiał AD, Olczak K, Ropka-Molik K. The Hucul horse breed formed in the region of the Eastern Carpathians, likely through the natural crossbreeding of oriental horses. After World War II, their population significantly decreased, leading to the breeding being based on only 14 female lines, whose founders often had unknown origins. To preserve the breed's unique characteristics, it is now part of a Genetic Resources Conservation Program, which prioritizes the maintenance of genetic diversity. This study aims to clarify the maternal relatedness of founder mares and assess genetic diversity using mitochondrial DNA (mtDNA). The hy...
Ming KM, Le Verger K, Geiger M, Schmelzle T, Georgalis GL, Shimbo G, Sasaki M, Ohdachi SD, Sánchez-Villagra MR.The horse () varieties from Skyros and Rhodes islands (Greece) in the Aegean archipelago are extremely small, reaching shoulder heights of only about 1 m. Furthermore, the Japanese archipelago is home to eight small, native horse breeds. We investigated the evolutionary morphology and provided a review of historical documentations of these horses of cultural interest in Greece and Japan, thus providing a comparison of the independent evolution of small size in islands. We integrate cranial data from historical literature with data from newly gathered and curated skulls and analyse a measureme...
Kuzmina TA, Königová A, Burcáková L, Babjak M, Syrota Y.This study aimed to examine the species diversity and structure of the strongylid community in domestic horses in Eastern Slovakia. Also, an analysis of the impact of age, sex, and collection location factors on the strongyid communities was performed. Methods: Twenty-seven horses 1.5-21 years old from two farms in eastern Slovakia with different horse-management conditions were studied. Strongylids were collected after horse treatments with Noromectin (0.2 mg ivermectin); 66,170 specimens were collected and identified. Faecal egg count reduction test (FECRT) was performed following fenbendaz...
Linnegar B, Kerlin DH, Eby P, Kemsley P, McCallum H, Peel AJ.To identify the size and distribution of the horse population in the Northern Rivers Region of NSW, including changes from 2007 to 2021, to better understand populations at risk of Hendra virus transmission. Methods: Census data from the 2007 Equine Influenza (EI) outbreak were compared with data collected annually by New South Wales Local Land Services (LLS) (2011-2021), and with field observations via road line transects (2021). Results: The horse populations reported to LLS in 2011 (3000 horses; 0.77 horses/km) was 145% larger than that reported during the EI outbreak in 2007 (1225 horses; ...
Bazan L, Argibay HD, Borges-Silva W, Pita Gondim LF, Dos Santos Mattos TA, Santana JO, da Silva EM, Begon M, Khalil H, Costa F, de Oliveira Carneiro I.Toxoplasma gondii is a globally neglected zoonotic parasite, particularly prevalent in socioeconomically vulnerable areas. Various animal species serve as reservoirs for T. gondii across different regions, including domestic cats, livestock, and a variety of wild and synanthropic animals. In urban areas, especially informal settlements, the close coexistence of humans, domestic animals, and wildlife may influence local transmission dynamics. This study evaluated the seroprevalence and associated risk factors for T. gondii infection in domestic and synanthropic animals from two low-income neigh...
Nakayama T.In Mongolia, the traditional pastoral system has changed by the overuse and degradation of water resources. However, there is a research gap between the socio-economic transition and ecosystem degradation on the existing knowledge. In the present study, a process-based eco-hydrology model, National Integrated Catchment-based Eco-hydrology (NICE), was coupled with inverse method (NICE-INVERSE) and applied to the total of 29 river basins in the entire country to quantify the heterogeneous distribution of livestock water use and its relation to pasture degradation there. The result showed that th...
Masuda M, Tozaki T, Kawate K, Furukawa R, Kikuchi M, Ishige T, Kakoi H.The Miyako horse is one of the eight Japanese native horse breeds and is scarce in terms of population size. Japanese native horses are believed to be descended from Mongolian horses and represent a precious lineage that has preserved its traits for over a thousand years in Japan. Genetic analysis of the endangered Miyako horse is useful for preserving its original phenotypic traits. This study analysed the genetic variation in trait-related genes for coat colour (), body composition (), gait (), and temperament () in 46 extant Miyako horses. In addition, because numerous Miyako horses have ve...
