Testing olfaction in equids: Age and gestational stage affects olfactory interest

In spite of the highly developed olfactory apparatus of horses, implying a high adaptive value, research on equine olfaction is sparse. Our limited knowledge poses a risk that horse behaviour does not match human expectations. The benefit of acquiring more knowledge of equine olfaction is therefore twofold; 1) it can aid the understanding of horse behaviour and hence reduce the risk of dangerous situations, and 2) there may be unexploited potential of using odours in several practical situations where humans interact with horses. This study investigated olfactory abilities of, 35 Icelandic, horses who were presented to four odours: peppermint, orange, lavender and cedarwood. The response variables were sniffing duration per presentation and behavioural reaction (licking, biting, snorting, and backing). Results showed horses were able to detect and distinguish between all four odours and showed increased interest (significantly longer sniffing duration) for peppermint. More horses expressed licking behaviour when presented to peppermint compared to cedarwood and lavender. Young horses sniffed cedarwood for longer than old horses, and pregnant mares sniffed lavender less than non-pregnant mares. In conclusion, the test paradigm seemed meaningful for horses, and olfactory interest of horses varied with age and gestational status but not sex.

A QTL for conformation of back and croup influences lateral gait quality in Icelandic horses

Background The back plays a vital role in horse locomotion, where the spine functions as a spring during the stride cycle. A complex interaction between the spine and the muscles of the back contribute to locomotion soundness, gait ability, and performance of riding and racehorses. Conformation is commonly used to select horses for breeding and performance in multiple horse breeds, where the back and croup conformation plays a significant role. The conformation of back and croup plays an important role on riding ability in Icelandic horses. However, the genes behind this trait are still unknown. Therefore, the aim of this study was to identify genomic regions associated with conformation of back and croup in Icelandic horses and to investigate their effects on riding ability. One hundred seventy-seven assessed Icelandic horses were included in the study. A genome-wide association analysis was performed using the 670 K+ Axiom Equine Genotyping Array, and the effects of different haplotypes in the top associated region were estimated for riding ability and additional conformation traits assessed during breeding field tests. Results A suggestive quantitative trait loci (QTL) for the score of back and croup was detected on Equus caballus (ECA) 22 (p-value = 2.67 × 10− 7). Haplotype analysis revealed two opposite haplotypes, which resulted in higher and lower scores of the back and croup, respectively (p-value < 0.001). Horses with the favorable haplotype were more inclined to have a well-balanced backline with an uphill conformation and had, on average, higher scores for the lateral gaits tölt (p-value = 0.02) and pace (p-value = 0.004). This genomic region harbors three genes: C20orf85, ANKRD60 and LOC100056167. ANKRD60 is associated with body height in humans. C20orf85 and ANKRD60 are potentially linked to adolescent idiopathic scoliosis in humans. Conclusions Our results show that the detected QTL for conformation of back and croup is of importance for quality of lateral gaits in Icelandic horses. These findings could result in a genetic test to aid in the selection of breeding horses, thus they are of major interest for horse breeders. The results may also offer a gateway to comparative functional genomics by potentially linking both motor laterality and back inclination in horses with scoliosis in humans.

Metabolic impact of weight variations in Icelandic horses

Background Insulin dysregulation (ID) is an equine endocrine disorder, which is often accompanied by obesity and various metabolic perturbations. The relationship between weight variations and fluctuations of the insulin response to oral glucose tests (OGT) as well as the metabolic impact of ID have been described previously. The present study seeks to characterize the concomitant metabolic impact of variations in the insulin response and bodyweight during repeated OGTs using a metabolomics approach. Methods Nineteen Icelandic horses were subjected to five OGTs over one year and their bodyweight, insulin and metabolic response were monitored. Analysis of metabolite concentrations depending on time (during the OGT), relative bodyweight (rWeight; defined as the bodyweight at one OGT divided by the mean bodyweight across all OGTs) and relative insulin response (rAUCins; defined accordingly from the area under the insulin curve during OGT) was performed using linear models. Additionally, the pathways significantly associated with time, rWeight and rAUCins were identified by rotation set testing. Results The results suggested that weight gain and worsening of ID activate distinct metabolic pathways. The metabolic profile associated with weight gain indicated an increased activation of arginase, while the pathways associated with time and rAUCins were consistent with the expected effect of glucose and insulin, respectively. Overall, more metabolites were significantly associated with rWeight than with rAUCins.

The star of the show: the Icelandic horse.

The Icelandic horse is one of the purest horse breeds in the world, reaching an average 140 cm (13.3 hh) height at the withers and weighing 340 kg. The conformation is rectangular and compact, with a sloping croup, and a long, thick mane and tail. The breed is most known and appreciated for the lateral gaits tölt and pace, which it has in addition to the basic gaits (walk, trot and canter/gallop). The breed is found in more than 30 countries, with more Icelandic horses abroad (ca. 175,000) than in Iceland (ca. 65,000). There is one international studbook, WorldFengur, with breeding associations in 21 countries and a common breed evaluation system. Following mechanization in Iceland around 1950, the role of the Icelandic horse changed from being 'the most useful servant' to that of a leisure and sport horse. Also in 1950, Landsmót - the largest outdoor sporting event for the Icelandic horse in Iceland - was held for the first time. It was then repeated every four years until 1998 and biennially after that. Landsmót has been held 23 times in total, at seven different locations in the south and north of Iceland, lasting for 3-8 days in the high summer period. The event has expanded over time with an increasing number of horses, riders and competition disciplines. This chapter introduces the disciplines, qualification of horses and riders and facilities required for Landsmót.

FEIF, the International Federation of Icelandic Horse Associations.

This chapter discusses the vision, structure and activities of the International Federation of Icelandic Horse Associations (FEIF). The biggest and most visible event run in the name of FEIF is the biennial World Championships for Icelandic Horses.

Speed of gaits in Icelandic horses and relationships to sex, age, conformation measurements and subjective judges’ scores

The aim was to measure the mean and maximum speed and the range of speed in all gaits of Icelandic horses shown at a breed evaluation field test (BEFT). In addition, the effect of speed on scores for the gaits and whether speed was affected by age, sex and conformation measurements were investigated. The study was carried out in Iceland on 266 horses (180 mares and 86 stallions). Horse speed and distance ridden were recorded by global positioning system during the riding assessment in BEFT. Conformation measurements and scores for each gait were obtained from the official studbook Worldfengur. The range of speed in walk, slow tölt, tölt, trot, pace, canter and gallop was, respectively, 1.5-2.2, 3.2-5.5, 4.6-10.6, 4.5-8.6, 7.1-11.9, 5.8-9.8 and 7.9-13.5 m/s (n=149-248). Scores for all gaits were affected by speed of the gait, with speed explaining most variance in scores for pace (53%) and least in scores for slow tölt and walk (2 and 3%, respectively). Stallions were faster than mares in tölt, trot, pace and canter (P<0.05). Horses aged ≥7 years and 6-year-olds were faster in pace and canter than 4-year-olds (P<0.05). Horse conformation measurements most affected speed in pace and walk, which were elevated with increased height at withers, height at croup, body length and length of front legs (P<0.05). In conclusion, objective measurements of speed in the gaits of Icelandic horses shown in a BEFT were documented for the first time. The information can be used to formulate requirements for gaits in BEFT and in competition manuals. Objective measurements of speed should be used in future assessments of gaits in Icelandic horses in BEFT, and thus improve standardisation and genetic evaluation of breeding horses.