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Topic:Animal Studies
Animal studies involving horses encompass a range of research focused on understanding equine biology, behavior, and health. These studies often investigate various aspects of horse physiology, genetics, nutrition, and disease pathology. Researchers utilize animal studies to explore the effects of different treatments, management practices, and environmental factors on horse welfare and performance. The findings from such studies contribute to the development of improved care strategies and health interventions. This page gathers peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of animal studies conducted on horses, providing insights into their application in advancing equine science.
Forms of employment and species caseload of veterinary practitioners in New Zealand. A survey by means of a postal questionnaire was undertaken to investigate the patterns of work and the need for information of veterinary practitioners in New Zealand. Of the 670 eligible veterinarians, 399 practitioners (60 per cent) participated in the survey. Of these, 38 per cent were in large animal practice (less than 20 per cent of work devoted to cats and dogs) and 31 per cent were in small animal practice (more than 80 per cent of work with cats and dogs). The remaining 31 per cent were in mixed practice, with a workload intermediate between the other two groups. Across the entire sam...
Large intestinal capacity, retention times, and turnover rates of particulate ingesta associated with extensive large-colon resection in horses. Fecal excretion of a particulate marker, ytterbium (Yb), was evaluated in 9 horses before surgery and 3 weeks, 3 months, and 6 months (4 trials) after sham-operation (group 1; n = 3) or extensive large colon resection (group 2; n = 6). Fecal excretion curves of total Yb excretion, loge Yb excretion, % Yb excretion, loge % Yb excretion, and cumulative % Yb excretion were evaluated, and kinetic analysis was performed on the loge Yb excretion curves to detect mixing pools and to calculate the fractional rate of particulate passage, turnover rate, and pool size. Calculations were performed to dete...
High frequency jet ventilation in horses: an experimental study. High frequency jet ventilation (HFJV) is a recently developed mode of ventilation that delivers small tidal volumes at frequencies greater than 60 cycles per min via an injection catheter to the animal's airway. The construction of a high frequency jet ventilator suitable for use in adult horses is described. The effectiveness of this ventilator in maintaining normal arterial blood-gas tension was evaluated in five healthy adult horses. The horses were anaesthetised with intravenous acetylpromazine, guaifenesin, and thiamylal, positioned in lateral recumbency and baseline measurements were mad...
Culture of equine trophoblastic vesicles in vitro. Trophoblastic vesicles have been used to study early embryonic development and maternal recognition of pregnancy in domestic animals. The purpose of this study was to characterize the formation of trophoblastic vesicles from Day-12 to Day-16 equine conceptuses. Conceptuses (n = 19) were collected nonsurgically from mares, the capsule was removed, and the conceptus (trophoblast and inner cell mass) was dissected into 2- to 4-mm fragments. Conceptus fragments were cultured in either Ham's F10 (HF10) or Minimum Essential Media (MEM) with 10% fetal bovine serum (FBS) in 24-well plates. Plates were...
Radioimmunoassay of inhibin in various mammals. A sensitive radioimmunoassay (RIA) for the determination of inhibin in peripheral plasma and tissue homogenates of different species has been developed using antisera to partially purified bovine follicular fluid (bFF) inhibin and 125I-labelled bFF 32 kDa inhibin. Antisera were produced by immunization of rabbits with partially purified bFF inhibin prepared by immunoaffinity chromatography. Increasing doses of a high titre antiserum could neutralize the suppressing effect of bFF, porcine follicular fluid and rat ovarian homogenate on FSH secretion from rat anterior pituitary cells in culture. ...
Viral transcripts in cells infected with defective interfering particles of equine herpesvirus type 1. Equine herpesvirus type 1 (EHV-1) preparations enriched in defective interfering particles (DIPs) have previously been demonstrated to mediate the coestablishment of persistent infection and oncogenic transformation in primary hamster embryo fibroblasts. In this study, it was demonstrated that infection of a rabbit kidney (RK) cell line with EHV-1 DIP-enriched preparations also results in the establishment of persistent infection. Viral transcription was characterized in RK cells infected with DIP-enriched stocks and compared to viral transcription in RK cells infected with standard (STD) EHV-...
Postanesthetic compartmental syndrome in a horse. After surgery, high intramuscular pressures were measured in a horse with clinical signs of postanesthetic myopathy that developed following a 2.25-hour surgical procedure. In the postoperative period, tests for muscular and neurologic integrity were made, including measurement of intracompartmental muscle pressure.
Blood gas measurements during exercise: errors due to temperature correction. This study assessed the degree to which correcting blood gas measurements to rectal temperature (Tre) rather than to the temperatures at which gas exchange occurs [pulmonary arterial (Tpa) or intramuscular (Tm)] introduces errors into blood gas analysis of exercising mammals. Horses and steers weighing 450 kg were run on a treadmill at speeds up to those eliciting maximal rates of O2 consumption (VO2max), and temperatures were measured in various body compartments. In both species Tpa rose faster than Tre during the run, the degree of dissociation being a function of exercise intensity and dur...
Effect of weight loading on the coronary band interstitial fluid pressure in horses. Interstitial fluid pressures, as a possible function of limb load, were measured at 2 sites within the digital coronary dermis of both cranial digits in 10 standing horses. Fluid pressure changes and digital load measurements were simultaneously detected and recorded by use of, respectively, modified wick-in-needle and force plate transducers coupled to a microcomputer. Mean pressures, recorded at limb loads between 50 and 80 kg, were 2.29 +/- 3.17 mm of Hg at the toe and 2.49 +/- 5.91 mm of Hg at the heel. Mean pressures, recorded between 150 and 180 kg, were 5.01 +/- 5.23 mm of Hg at the toe...
Normal intestinal motility. Perhaps because of the inherent difficulty in using horses as experimental animals, only a relatively small amount of data is as yet available regarding normal equine gut motility. However, it is clear that the horse is fundamentally similar to other mammalian species studied. The neural and humoral control of gut activity requires much exploration; it is likely that, in the horse, some of this information will be derived during the investigation of the effects of various substances that might have clinical relevance. This is alluded to in the chapter that follows (The Effects of Pharmacologic...
[Seasonal changes in blood testosterone in the Giara horse]. The blood testosterone changes in three Giara stallions, average age 8 years old and average weight 183 Kgs, were checked weekly for a year using a radioimmunological method. The horses showed a highly seasonal hormonal activity concentrated in the first half of the year (winter and spring). In the second half of the year (summer and fall) the stallions showed low levels of testosterone. The highest level of the androgen hormone occurred in April, the lowest in October. The absolute levels of this hormone agreed substantially with the relative literature.
Oxygen transport during exercise in large mammals. I. Adaptive variation in oxygen demand. This study investigated mechanisms used by horses and steers to increase O2 uptake and delivery (VO2) from resting to maximal rates and identified the mechanisms that enable horses to achieve higher maximal rates of O2 consumption (VO2max) than steers. VO2 and circulatory variables were measured while Standardbred trotting horses and steers (450-kg body mass) stood quietly and ran on a treadmill at speeds up to those eliciting VO2max. As VO2 increased in both species, heart rate and circulating hemoglobin (Hb) concentration increased, thereby increasing O2 delivery by the circulation, while ca...
Oxygen transport during exercise in large mammals. II. Oxygen uptake by the pulmonary gas exchanger. Because the maximal rate of O2 consumption (VO2max) of the horse is 2.6 times larger than that of steers of equal size, we wondered whether their pulmonary gas exchanger is proportionately larger. Three Standardbred racehorses [body mass (Mb) = 447 kg] and three domestic steers (Mb = 474 kg) whose cardiovascular function at VO2max had been thoroughly studied (Jones et al. J. Appl. Physiol. 67: 862-870, 1989) were used to study their lungs by morphometry. The basic morphometric parameters were similar in both species. The nearly 2 times larger lung volumes of the horses caused the gas exchange ...
Gas conductance during high-frequency oscillatory ventilation in large animals. Three sheep, a foal, a pony, and a calf were anesthetized and ventilated for short periods, using a high-frequency oscillatory ventilator. The efficiency of CO2 elimination was characterized at various oscillatory frequencies (50 to 30 Hz) and various tidal volumes, although the tidal volume used was always less than the measured dead space of the animal. In general, increasing either the oscillatory frequency or tidal volume increased CO2 elimination, but increasing the tidal volume had more effect. The relationship between these 3 variables was best described by a power law equation. Ventila...
The primary structure of equine serum amyloid A (SAA) protein. The complete amino acid sequence of equine serum amyloid A (SAA) was elucidated. The protein consists of 110 amino acid residues and contains an 8-amino acid residue insertion tentatively located between positions 69 and 70, as compared with human SAA. Microheterogeneities were detected at positions 16, 44, and 59, compatible with the existence of more than one SAA gene in the horse. This corresponds to the situation in man and mouse. Pronounced homology with SAA from man and several animal species was observed, thus confirming the conserved structure of this acute phase reactant and apoprotei...
White-footed mice: tick burdens and role in the epizootiology of Potomac horse fever in Maryland. One hundred ten white-footed mice (Peromyscus leucopus) were captured on horse farms in south-central Maryland, examined for ticks, and tested for specific antibodies to Ehrlichia risticii, the causative agent of Potomac horse fever. Peromyscus leucopus were consistently infested with immature American dog ticks (Dermacentor variabilis), with monthly prevalences as high as 80%. Sera from all 97 P. leucopus tested for antibodies to E. risticii were negative. This indicates that P. leucopus is not a reservoir of E. risticii, and suggests that immature D. variabilis do not acquire E. risticii in ...
Functional and ligand binding studies suggest heterogeneity of platelet prostacyclin receptors. 1. This study describes attempts to compare prostacyclin (IP-) receptors in human, pig, horse, rabbit and rat platelets and in circular muscle of human, rabbit and dog mesenteric and pig gastroepiploic arteries. Three stable prostacyclin analogues, iloprost, cicaprost and 6a-carba-prostacyclin (6a-carba-PGI2) and a prostaglandin endoperoxide analogue EP 157 (previously shown to mimic prostacyclin on human platelets) were used. 2. Our main conclusion is that prostacyclin receptors on human, pig and horse platelets are similar in nature, but distinct from those on rabbit and rat platelets. Funct...
Effects of dopamine administration on cecal mechanical activity and cecal blood flow in conscious healthy horses. Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity of the circular and longitudinal muscle layers of the cecal body were measured in 7 conscious healthy horses during IV infusion of physiologic saline solution for 60 minutes (control), during a 60-minute IV infusion of dopamine (at dosages of 1, 2.5, and 5 micrograms/kg/min), and for 60 minutes after IV infusion of dopamine. The mean values for lateral cecal arterial blood flow during IV infusion of dopamine at a dosage of either 1 or 2.5 micrograms/kg/min were not significantly different from the...
Lymphoid nodules in skin biopsies from dogs, cats, and horses with nonneoplastic dermatoses. In a retrospective histopathologic study of nonneoplastic dermatoses, lymphoid nodules were found in 0.3% of 3,408 canine, 5.1% of 469 feline, and 4.5% of 325 equine skin biopsies. In all 3 species, the majority of cases wherein lymphoid nodules were found were diseases of presumed immune-mediated nature. In cats and horses, the majority of cases were also diseases characterized by tissue eosinophilia.
Effects of xylazine and/or butorphanol or neostigmine on myoelectric activity of the cecum and right ventral colon in female ponies. Effects of xylazine HCl (0.5 mg/kg of body weight, IV) and/or butorphanol tartrate (0.04 mg/kg, IV) or neostigmine methylsulfate (0.022 mg/kg, IV) on myoelectric activity of the cecum and right ventral colon were studied in 4 conscious female ponies. Eight bipolar Ag/AgCl electrodes were sequentially placed on the seromuscular layer of the cecum (6 electrodes) and right ventral colon (2 electrodes). Recordings began 30 minutes before and continued for 90 minutes after drug administration. Each drug or drug combination was studied on 2 occasions in each pony. Two major patterns of coordinated s...
The effect of exercise on the healing of articular cartilage defects in the equine carpus. Arthroscopic surgery was performed on 12 horses (2-4 years of age) to create a 7 x 14 mm full-thickness cartilage defect in one radial carpal bone and in the contralateral third carpal bone. Six horses remained confined to a small paddock and six horses underwent a program of increasing exercise consisting of walking, trotting, and cantering for 13 weeks. All lesions showed evidence of healing at week 6 that progressed to more complete healing at week 13. There was no difference in the amount of repair tissue covering the defect. Histologically, the lesions healed with a combination of fibrous...
Application of a Hall-effect transducer for measurement of tendon strains in horses. Custom-designed Hall-effect strain sensors (HES) were implanted surgically onto the superficial digital flexor tendons of the forelimbs of 4 adult Thoroughbreds. Strains were recorded at various gaits, using a portable amplifer and FM cassette recorder. Strain calculations used the original length (L) as the HES position with the forelimb in the relaxed neutral position during anesthesia. A characteristic deflection in the strain cycle recording was confirmed to correspond to initial hoof contact with the ground (heel strike) by simultaneous recording of weight bearing via a footswitch. Heel s...
[The dust and microbial content in a horse stable during the use of a dust-binding agent]. Dust in horse barns is assumed to contribute to pulmonary disease, it is attempted to reduce the airborne dust by soaking or sprinkling the hay before feeding. Both means cause considerable efforts and increase the relative humidity of the air. This is why a commercial dust-binding agent (Revesto pur) was used in a pilot investigation which was carried out during 2 weeks - one week for control and one week using the agent - in a private horse barn where three horses were regularly stable. The airborne dust was measured by a continuously working instrument. Once a day (7.00 a.m.) the number of ...
Postprandial serum gastrin concentrations in normal foals. Postprandial gastrin concentrations were assayed in serum samples from a group of six foals at one day, one week, one month and three months of age. Before sampling, each foal was prevented from feeding for 2 h and was then allowed to suck for 15 mins. Blood samples were taken at the start of the meal and at 30 min intervals for the next 3 h. Feeding increased serum gastrin concentrations at one day, one week and one month, with the greatest increases detected at one day. Mean pre-feeding gastrin concentrations were 25.2 +/- 2.3 pg/ml at one day, 22.8 +/- 3.9 pg/ml at one week, 15.2 +/- 2.3 pg...
Retinal vascular patterns in domestic animals. In this paper a morphological study of the retinal vascular patterns in various species of domestic animals is reported. A classification of these patterns into four well-defined groups is described. In the domestic ruminants, pigs and carnivores the retina contains a compact plexus of blood vessels located in the major part of the light-sensitive portion of the retina (euangiotic or holangiotic pattern). In other domestic animals blood vessels are present only in a smaller part of the retina. In the rabbit, vessels are confined to a broad horizontal band coincident with the area of dispersion...
Transfer of deep circumflex iliac flaps to the tarsus by microvascular anastomosis in the horse. Eighteen deep circumflex iliac flaps were elevated in healthy adult horses. Four flaps survived well when elevated as islands, but five orthotopic flaps and nine heterotopic flaps transferred to the tarsus and face failed. Technical reasons could explain the failure of the orthotopic flaps, but not the heterotopic flaps. Failure of the heterotopic flaps was apparently caused by the no-reflow phenomenon.
Mössbauer spectroscopic study of the initial stages of iron-core formation in horse spleen apoferritin: evidence for both isolated Fe(III) atoms and oxo-bridged Fe(III) dimers as early intermediates. Ferritin stores iron within a hollow protein shell as a polynuclear Fe(III) hydrous oxide core. Although iron uptake into ferritin has been studied previously, the early stages in the creation of the core need to be clarified. These are dealt with in this paper by using Mössbauer spectroscopy, a technique that enables several types of Fe(II) and Fe(III) to be distinguished. Systematic Mössbauer studies were performed on samples prepared by adding 57Fe(II) atoms to apoferritin as a function of pH (5.6-7.0), n [the number of Fe/molecule (4-480)], and tf (the time the samples were held at room ...
Structure of the alpha 1 subunit of horse Na,K-ATPase gene. Genomic DNA for Na,K-ATPase alpha 1 subunit was obtained from libraries of horse kidney genomic DNA in Charon 4A and in EMBL3 bacteriophages by screening with the full sized cDNA probe of the alpha 1 subunit of rat Na,K-ATPase as probe. The gene spans 30 kb and consists of 23 exons and 22 intervening sequences. Intron-exon boundaries were analyzed. The protein-coding nucleotide sequence encodes 1016 amino acids with an Mr of 112,264. The putative amino acid sequence of horse alpha 1 is 96-97% homologous to those of other mammalian species.
