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Interspecific pregnancies, in which mares carry horse-donkey hybrid fetuses (mule pregnancies), present physiological challenges distinct from typical horse pregnancies, especially regarding placental development and uterine hemodynamics. While doppler ultrasonography is well-established for assessing uterine artery blood flow in horses, its application in interspecific pregnancies remains limited, creating a gap in reproductive management for mule production programs. This study compared pulsatility (PI) and resistivity (RI) indices of uterine arteries in mares carrying horse (GS, n = 13) or donkey (GD, n = 13) pregnancies throughout gestation, while evaluating effects of maternal age. Using transrectal Doppler ultrasonography (SonoScape S6[R], 3-7MHz), bilateral uterine artery measurements were performed every 15 days until 150 days and monthly thereafter until parturition. Results revealed distinct hemodynamic patterns: GD pregnancies showed delayed peak PI (66-80 days vs GS: 20-35 days) and earlier stabilization (186-215 days vs GS: 306-335 days), suggesting altered placental maturation. A significant age effect was observed, with older mares exhibiting higher RI in the right uterine artery (r = 0.107, P < 0.05). While GS mares showed bilateral PI reduction, GD mares displayed unilateral (left artery) changes, indicating asymmetric adaptation. These findings provided the first reference values for uterine artery indices in interspecific equine pregnancies, demonstrating that standard horse pregnancy parameters cannot be directly applied to donkey pregnancies. The study established Doppler ultrasonography as a valuable tool for monitoring hybrid pregnancies and highlights the need for species-specific management approaches in equine reproduction, particularly for aging mares in mule breeding programs. Future research should investigate molecular mechanisms underlying these hemodynamic differences and explore targeted interventions to optimize pregnancy outcomes. Key words: breeder, donkey, stallion, hemodynamic, interspecific pregnancy. As gestacoes interespecificas, nas quais eguas carregam fetos hibridos de cruzamento entre cavalo e jumento (gestacoes de mulas), apresentam desafios fisiologicos distintos das gestacoes equinas usuais, especialmente no que se refere ao desenvolvimento placentario e a hemodinamica uterina. Embora a ultrassonografia doppler seja amplamente utilizada para avaliar o fluxo sanguineo das arterias uterinas em eguas, sua aplicacao em gestacoes interespecificas ainda e limitada, criando uma lacuna no manejo reprodutivo de programas voltados a producao de mulas. Este estudo teve como objetivo comparar os indices de pulsatilidade (IP) e resistividade (IR) das arterias uterinas em eguas gestantes de cavalos (GS, n = 13) e de jumentos (GD, n = 13) ao longo da gestacao, alem de avaliar os efeitos da idade materna. Utilizando ultrassonografia Doppler transretal (SonoScape S6[R], 3-7 MHz), foram realizadas medicoes bilaterais das arterias uterinas a cada 15 dias ate 150 dias de gestacao e, posteriormente, mensalmente ate o parto. Os resultados revelaram padroes hemodinamicos distintos: as gestacoes GD apresentaram pico de IP tardio (66-80 dias vs. GS: 20-35 dias) e estabilizacao mais precoce (186-215 dias vs. GS: 306-335 dias), sugerindo maturacao placentaria alterada. Observou-se tambem efeito significativo da idade, com eguas mais velhas apresentando maior IR na arteria uterina direita (r = 0,107; P < 0,05). Enquanto as eguas GS mostraram reducao bilateral do IP, as eguas GD exibiram alteracoes unilaterais (na arteria esquerda), indicando adaptacao assimetrica. Esses achados fornecem os primeiros valores de referencia para indices das arterias uterinas em gestacoes equinas interespecificas, demonstrando que parametros utilizados em gestacoes de eguas nao podem ser aplicados diretamente as gestacoes de jumentas. O estudo estabelece a ultrassonografia Doppler como uma ferramenta valiosa para o monitoramento de gestacoes hibridas e destaca a necessidade de abordagens de manejo especificas na reproducao equina, especialmente para eguas mais idosas empregadas em programas de producao de mulas. Pesquisas futuras devem investigar os mecanismos moleculares subjacentes a essas diferencas hemodinamicas e explorar intervencoes direcionadas para otimizar os resultados gestacionais. Palavras-chave: reprodutor, jumento, garanhao, hemodinamica, gestacao interespecifica.

In Brazil, the production of gaited mules has been a prominent activity in agribusiness. The selection of gaited saddle mules with a comfortable gait for covering long distances at low speeds involves crossing marching donkeys of the Pêga breeds with horses, preferably those belonging to the Mangalarga Marchador and Campolina breeds. The reference-C and non-reference-A alleles of the DMRT3:g.22999655C>A SNP are linked with different horse gaits, including the batida gait (diagonalized) and the picada gait (lateralized) in Mangalarga Marchador and Campolina horses, respectively. Since donkeys (Equus asinus) and mules (E. asinus ♂ x E. caballus ♀) also exhibit these gaits, this study aimed to determine whether the genotype affects the gait type in these animals. The higher frequency of CA mules and the rare presence of the A allele of DMRT3 in donkeys match previous findings in Mangalarga Marchador and Campolina horses, which are crucial in creating marching mules in Brazil. This suggests that the A allele likely came from the mares used in mating with donkeys. Furthermore, our findings suggest that factors beyond this gene variant, such as other genes and genetic variations, play a role in gait characteristics in equids. In Brazil, the production of mules with a comfortable gait primarily involves the breeding of marching saddle mules. This is achieved by crossing gaited Pêga donkeys with horses from the Mangalarga Marchador and Campolina breeds. The DMRT3:g.22999655C>A SNP is implicated in regulating gait phenotypes observed in various horse breeds, including the batida (CC) and picada (CA) gaits found in these horse breeds. We aimed to determine if genotypes influenced gait type in 159 mules and 203 donkeys genotyped for the DMRT3 SNP by PCR-RFLP analysis. About 47% of mules had the CC-genotype, while 53% had the CA-genotype. Donkeys predominantly had the CC-genotype (97%), and none had AA. Both CC- and CA-genotypes were evenly distributed among mules with the batida or picada gaits. In donkeys, the CC-genotype frequencies were consistent regardless of gait type. However, the CA-genotype was more common in picada-gaited donkeys than in batida-gaited donkeys. The prevalence of CA mules and the rare presence of the non-reference allele in donkeys align with previous findings in Mangalarga Marchador and Campolina horses. This suggests that the non-reference allele likely originated from the mares involved in donkey crosses. Our results also imply that factors beyond this variant, such as other genes and polymorphisms, influence gait traits in equids.

Having separated from the one-armed trapper who taught him how to survive in the wilderness of the Old West, fifteen-year-old Francis gets lost and continues to have adventures involving dangerous men and a friendly mule.

Knowing how many donkeys there are in specific countries where welfare is compromised is a key concern for targeting efforts to improve donkey welfare. Additionally, accurate population estimates are vital for providing evidence and addressing the impact of population threats. The FAO annually report the number of donkeys and mules in each country. The last paper to investigate global and region trends dates back to 2000 and used FAO data from 1961 to 1997. This paper is an update focusing on global, regional and country level donkey and mule populations to understand if there have been any changes in the trends reported by the previous study between 1997 and 2018. Results show that the general trend identified between 1961 and 1997 is continuing with the number of donkeys globally increasing at a rate of ~1% per annum whilst mule populations are in decline at a rate of ~2% per annum. Results also suggest that the trend identified in the original paper are still evident today with the largest increases in donkey population seen in the sub-Saharan African region and greatest reduction noted in Eastern Europe with these two regions having different socio-economic drivers influencing these changes. These results highlight the multifaceted socio-economic drivers influence changes in donkey and mule populations demonstrating the complexity of designing targeted one-welfare approaches. Whilst the FAO donkey and mule datasets are the best available for understanding spatial-temporal distributions in populations there needs to be greater effort to promote the communication of information from the country level to the FAO. This can be directly supported by NGO’s by promoting the robustness of the FAO process for collating and disseminating this information. NGO’s should also seek to highlight the importance of this information for understanding global regional and country level drivers for equid population changes and potential threats to welfare as well as using this information to facilitate projects that support one-welfare approaches.

Donkeys have historically been among our most useful domesticated animals--from plowing fields to navigating difficult terrain; however, they have been much maligned in popular culture and given very little respect. Jill Bough champions this humble creature, proving that after 10,000 years of domestication, this incredibly hard-working animal deserves our appreciation. With accounts that are both fascinating and touching, this cultural history of the donkey will inspire a new respect and admiration for this essential creature.

The discovery of genomic imprinting through studies of manipulated mouse embryos indicated that the paternal genome has a major influence on placental development. However, previous research has not demonstrated paternal bias in imprinted genes. We applied RNA sequencing to trophoblast tissue from reciprocal hybrids of horse and donkey, where genotypic differences allowed parent-of-origin identification of most expressed genes. Using this approach, we identified a core group of 15 ancient imprinted genes, of which 10 were paternally expressed. An additional 78 candidate imprinted genes identified by RNA sequencing also showed paternal bias. Pyrosequencing was used to confirm the imprinting status of six of the genes, including the insulin receptor (INSR), which may play a role in growth regulation with its reciprocally imprinted ligand, histone acetyltransferase-1 (HAT1), a gene involved in chromatin modification, and lymphocyte antigen 6 complex, locus G6C, a newly identified imprinted gene in the major histocompatibility complex. The 78 candidate imprinted genes displayed parent-of-origin expression bias in placenta but not fetus, and most showed less than 100% silencing of the imprinted allele. Some displayed variability in imprinting status among individuals. This variability results in a unique epigenetic signature for each placenta that contributes to variation in the intrauterine environment and thus presents the opportunity for natural selection to operate on parent-of-origin differential regulation. Taken together, these features highlight the plasticity of imprinting in mammals and the central importance of the placenta as a target tissue for genomic imprinting.

To assess the susceptibility of elk (Cervus canadensis) and mule deer (Odocoileus hemionus) to SARS-CoV-2, we performed experimental infections in both species. Elk did not shed infectious virus but mounted low-level serologic responses. Mule deer shed and transmitted virus and mounted pronounced serologic responses and thus could play a role in SARS-CoV-2 epidemiology.

Effective mortality thresholds are critical for timely reporting and management of highly pathogenic avian influenza. Using standard modelling techniques, we evaluated the performance of different mortality thresholds in mule duck flocks. Using an eightfold increase of the mortality for two consecutive days compared to the average mortality the previous week led to a perfect classification of all flocks used for validation (12 affected and 18 non-affected flocks). A fixed daily threshold of 0.25% showed a perfect sensitivity and a good specificity (3 false positives/18). Our results fill a knowledge gap and can inform HPAI surveillance policy in non-vaccinated mule ducks.