Standing hand-assisted laparoscopic ovariohysterectomy to treat chronic pyometra in a mare.

OBJECTIVE: To describe a standing hand-assisted laparoscopic ovariohysterectomy in a mare. ANIMAL: A 15-year-old maiden Oldenburg mare. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The mare was presented for evaluation of bucking under saddle and uncharacteristic aggressive behavior. Evaluation of a 24-hour video of the mare in a stall showed behavior consistent with caudal visceral abdominal discomfort. Reproductive evaluation revealed a pyometra secondary to complete transluminal cervical adhesions. The mare was initially managed medically with disruption of the adhesions and uterine lavage, but the adhesions reformed within 6 weeks and could not be manually disrupted. TREATMENT AND OUTCOME: To eliminate the recurrence of pyometra, the mare underwent standing hand-assisted laparoscopic ovariohysterectomy through bilateral flank incisions. The only complication was a seroma at 1 flank incision that resolved after drainage. CLINICAL RELEVANCE: Complete ovariohysterectomy in the mare is a challenging procedure and has previously been performed under general anesthesia. This is the first report of the procedure being performed completely in the standing mare without inversion of the uterus through the cervix.

Efficacy of Lidocaine Topical Solution in Reducing Discomfort Reaction of Horses to Intramuscular Vaccination.

Vaccinations via intramuscular injection are a key component of preventative health care in horses. Development of problematic behavioral aversion to injections is quite common. Our clinical impression has been that topical anesthetic applied to injection sites can reduce the behavioral reaction; however, this has not been critically tested. To blindly evaluate efficacy, either 5% or 10% topical lidocaine solution or 0% control was applied to injection sites for 78 ponies two minutes before intramuscular vaccination. Mean reaction scores on a scale of 0-3 were 0.84 (se 0.18) for 5% lidocaine solution, 0.62 (se 0.14) for 10% lidocaine solution, compared to 1.30 (se 0.19) for 0% control solution. Reaction scores for both the 5% and 10% lidocaine were significantly lower than for the control group. Additionally, the proportion of subjects with a reaction greater than a slight flinch was 2 of 25 for the 5% lidocaine, 5 of 26 for the 10% lidocaine and 15 of 27 for the 0% lidocaine control. For both the 5% and 10% lidocaine groups, the proportion differed significantly from the control. The difference between the 5% and 10% lidocaine groups was not statistically significant. These findings confirm our clinical impression that application of topical anesthetic just two minutes in advance of intramuscular injection can effectively reduce the behavior reaction of horses.

A critical evaluation for validation of composite and unidimensional postoperative pain scales in horses.

Proper pain therapy requires adequate pain assessment. This study evaluated the reliability and validity of the Unesp-Botucatu horse acute pain scale (UHAPS), the Orthopedic Composite Pain Scale (CPS) and unidimensional scales in horses admitted for orthopedic and soft tissue surgery. Forty-two horses were assessed and videotaped before surgery, up to 4 hours postoperatively, up to 3 hours after analgesic treatment, and 24 hours postoperatively (168 video clips). After six evaluators viewing each edited video clip twice in random order at a 20-day interval, they chose whether analgesia would be indicated and applied the Simple Descriptive, Numeric and Visual Analog scales, CPS, and UHAPS. For all evaluators, intra-observer reliability of UHAPS and CPS ranged from 0.70 to 0.97. Reproducibility was variable among the evaluators and ranged from poor to very good for all scales. Principal component analysis showed a weak association among 50% and 62% of the UHAPS and CPS items, respectively. Criterion validity based on Spearman correlation among all scales was above 0.67. Internal consistency was minimally acceptable (0.51-0.64). Item-total correlation was acceptable (0.3-0.7) for 50% and 38% of UHAPS and CPS items, respectively. UHAPS and CPS were specific (90% and 79% respectively), but both were not sensitive (43 and 38%, respectively). Construct validity (responsiveness) was confirmed for all scales because pain scores increased after surgery. The cut-off point for rescue analgesia was ≥ 5 and ≥ 7 for the UHAPS and CPS, respectively. All scales presented adequate repeatability, criterion validity, and partial responsiveness. Both composite scales showed poor association among items, minimally acceptable internal consistency, and weak sensitivity, indicating that they are suboptimal instruments for assessing postoperative pain. Both composite scales require further refinement with the exclusion of redundant or needless items and reduction of their maximum score applied to each item or should be replaced by other tools.

Equine Discomfort Ethogram.

In recent years, there has been a growing interest in and need for a comprehensive ethogram of discomfort behavior of horses, particularly for use in recognizing physical discomfort in domestically managed horses. A clear understanding of the physical discomfort behavior of horses among caretakers, trainers, and professional health care personnel is important to animal welfare and caretaker safety. This is particularly relevant to pain management for hospitalized equine patients. Various pain scale rubrics have been published, typically incorporating only a few classically cited pain behaviors that, in many cases, are specific to a particular body system, anatomic location, or disease condition. A consistent challenge in using these rubrics in practice, and especially in research, is difficulty interpreting behaviors listed in various rubrics. The objective of this equine discomfort ethogram is to describe a relatively comprehensive catalog of behaviors associated with discomfort of various degrees and sources, with the goal of improving understanding and clarity of communication regarding equine discomfort and pain. An inventory of discomfort-related behaviors observed in horses has been compiled over 35 years of equine behavior research and clinical consulting to medical and surgical services at the University of Pennsylvania School of Veterinary Medicine's equine hospital. This research and clinical work included systematic evaluation of thousands of hours of video-recordings, including many hundreds of normal, healthy horses, as well as hospitalized patients with various complaints and/or known medical, neurologic, or orthopedic conditions. Each of 73 ethogram entries is named, defined, and accompanied by a line drawing illustration. Links to online video recorded examples are provided, illustrating each behavior in one or more hospitalized equine patients. This ethogram, unambiguously describing equine discomfort behaviors, should advance welfare of horses by improving recognition of physical discomfort, whether for pain management of hospitalized horses or in routine husbandry.

Harem stallion changes are not associated with diminished reproductive performance of females in semi-feral Konik polski horses (Equus caballus).

Infanticide, related to a stallion's aggression toward a foal sired by another stallion, and feticide related to a new stallion's aggression and/or pheromonal influence (the Bruce effect) inducing loss of a fetus sired by another stallion, a female's counteraction to infanticide, have been proposed for domestic horses (Equus caballus) in human-managed conditions. The aim of the present study was, in conditions close to natural, to investigate the influence of the natural succession of a harem stallion on the mares' subsequent reproductive performance. In a population of semi-feral Konik polski horses observed for 31 years (reproductive seasons) in 8 bands, harem stallion changed 10 times. These changes involved 26 out of 48 mares and 60 out of 609 observed mare-seasons (MS, a year in which a mare experienced a reproductive event). Binary distribution and log link function were assumed. The marginal model included the classification variable (SCH) and the continuous variables (age of the mare and calendar year of reproductive event (birth of a live foal, abortion, foals lost or barrenness) in a given MS was analyzed with generalized linear mixed model. The reproductive fitness of mares and their reproductive success (foal surviving ≥ 1 year), did not differ between MS with and without SCH. Older females were more likely to stay barren, with chances increasing by 21% with each successive year; and less likely to give birth to a foal (13% decrease of chance), and rear a foal to one year of age (12% decrease of chance). The age did not affect the probability of abortions. Of the 26 MS when mares were pregnant when the stallion had changed, there were 25 healthy foals born. For the entire 31 years of monitoring, no aggression toward any foal was observed and all foals that were born in the harem of a new, succeeding stallion successfully reached adulthood. Due to the lack of incidents of infanticide and the lack of evidence suggesting that the presence of a new harem stallion leads to the termination of pregnancies sired by another stallion, the Bruce effect was not confirmed as a biological strategy to reduce investment in pregnancy and potential infanticide in studied population of semi-feral horses.

In-Person Caretaker Visits Disrupt Ongoing Discomfort Behavior in Hospitalized Equine Orthopedic Surgical Patients.

Horses have evolved to show little indication of discomfort or disability when in the presence of potential predators, including humans. This natural characteristic complicates the recognition of pain in equine patients. It has been our clinical impression that, whenever a person is present, horses tend to "perk up" and ongoing discomfort behavior (DB) more or less ceases. The objective of this study was to quantitatively evaluate and describe this effect. For each of 20 orthopedic surgical patients, continuous 24-h video was reviewed to record all occurrences of DB during a caretaker visit (3.23 to 7.75 min), for comparison to the hour preceding as well as the hour following when undisturbed. The mean ± S.E. DB observed per minute during the preceding and following hours, respectively, were 1.65 ± 0.17 and 1.49 ± 0.22. The difference was not significant (p > 0.05). In contrast, mean DB per minute during the visit was 0.40 ± 0.11. This was significantly lower than during both the preceding and following hours (p < 0.0001). All 20 patients expressed fewer observable DB per minute during the visit, with a mean reduction of 77.4% ± 0.17%. For 30% of these patients, ongoing DB ceased altogether during the visit. These findings confirm our clinical impression that caretaker visits interrupt DB, resulting in under-appreciation of discomfort.

Preliminary Proof of the Concept of Wild (Feral) Horses Following Light Aircraft into a Trap.

Feral horses, wherever managed, typically require population control involving capture for permanent removal or repeatedly for fertility control treatments. The most common method for capturing feral horses is helicopter chasing into traps. With this fear-based strategy, it is difficult to safely capture entire groups. Recapture becomes increasingly difficult, with greater safety risks for pilots and ground staff. As preliminary proof of the concept of capturing free-roaming horses by leading into enclosures with light aircraft rather than driving with helicopters, a consumer-grade quadcopter drone was used to lead a herd of 123 semi-feral ponies into simulated traps. The technique was successful on the first attempt as well as for seven of nine additional attempts over a period of 4 weeks, repeatedly to the same as well as to different destinations. The pace of following was primarily a fast walk, with occasional slow trot. Family integrity was maintained. This work demonstrates preliminary proof of the concept of repeated capture of horses by leading with aircraft rather than chasing. If successfully demonstrated in more extensive rangeland conditions, this method may eventually provide a lower-stress, more repeatable option of capturing feral horses, with implications for improved animal and human safety and welfare.

Development of the equine hindgut microbiome in semi-feral and domestic conventionally-managed foals.

BACKGROUND: Early development of the gut microbiome is an essential part of neonate health in animals. It is unclear whether the acquisition of gut microbes is different between domesticated animals and their wild counterparts. In this study, fecal samples from ten domestic conventionally managed (DCM) Standardbred and ten semi-feral managed (SFM) Shetland-type pony foals and dams were compared using 16S rRNA sequencing to identify differences in the development of the foal hindgut microbiome related to time and management. RESULTS: Gut microbiome diversity of dams was lower than foals overall and within groups, and foals from both groups at Week 1 had less diverse gut microbiomes than subsequent weeks. The core microbiomes of SFM dams and foals had more taxa overall, and greater numbers of taxa within species groups when compared to DCM dams and foals. The gut microbiomes of SFM foals demonstrated enhanced diversity of key groups: Verrucomicrobia (RFP12), Ruminococcaceae, Fusobacterium spp., and Bacteroides spp., based on age and management. Lactic acid bacteria Lactobacillus spp. and other Lactobacillaceae genera were enriched only in DCM foals, specifically during their second and third week of life. Predicted microbiome functions estimated computationally suggested that SFM foals had higher mean sequence counts for taxa contributing to the digestion of lipids, simple and complex carbohydrates, and protein. DCM foal microbiomes were more similar to their dams in week five and six than were SFM foals at the same age. CONCLUSIONS: This study demonstrates the impact of management on the development of the foal gut microbiome in the first 6 weeks of life. The higher numbers of taxa within and between bacterial groups found in SFM dams and foals suggests more diversity and functional redundancy in their gut microbiomes, which could lend greater stability and resiliency to these communities. The colonization of lactic acid bacteria in the early life of DCM foals suggests enrichment in response to the availability of dams' feed. Thus, management type is an important driver of gut microbiome establishment on horses, and we may look to semi-feral horses for guidance in defining a healthy gut microbiome for domestic horses.

Evaluation of the effect of laboratory methods on semen analysis and breeding soundness examination (BSE) classification in stallions.

The stallion Breeding Soundness Examination (BSE), as proposed by the Society for Theriogenology, recommends that a stallion produce a minimum of one billion progressively motile, morphologically normal sperm (PMMNS) in the second of two ejaculates collected 1 h apart to be classified as a Satisfactory Prospective Breeder. With this in mind, the first objective of this study was to determine if the classification outcome of the traditional BSE differs depending on the methods used to evaluate sperm motility, morphology and concentration. We hypothesized that application of Computer Assisted Sperm Motion Analysis (CASA) and Differential Interference Contrast (DIC) microscopy to stallion semen evaluation would yield a more conservative estimate of the number of PMMNS. If this hypothesis is correct, then the use of CASA and DIC microscopy for semen evaluation would result in significantly fewer stallions meeting the historical standards for classification as a Satisfactory Prospective Breeder. Additionally, we determined whether the use of these modern technologies resulted in more accurate prediction of the actual fertility of a stallion compared to the use of more traditional technologies. Our results support the hypothesis that modern semen analysis techniques (including CASA and DIC microscopy) result in more conservative estimates of the number of PMMNS when compared to standard semen analysis techniques. As a result, the choice of methods used for semen analysis may impact the outcome of the traditional BSE. However, none of the methodologies used in this study reliably predicted different levels of fertility among this group of moderately to highly fertile stallions within the context of the traditional BSE. Additionally, the only individual semen measure that was significantly correlated with fertility was the percentage of morphologically normal sperm as determined using DIC microscopy. These results caution against strict use of the traditional 'cutoff' of 1 billion PMMNS for classification of breeding potential, particularly when attempting to differentiate between moderately and highly fertile stallions and regardless of the laboratory methods employed for semen analysis.

Frameshift Variant in MFSD12 Explains the Mushroom Coat Color Dilution in Shetland Ponies.

Mushroom is a unique coat color phenotype in Shetland Ponies characterized by the dilution of the chestnut coat color to a sepia tone and is hypothesized to be a recessive trait. A genome wide association study (GWAS), utilizing the Affymetrix 670K array (MNEc670k) and a single locus mixed linear model analysis (EMMAX), identified a locus on ECA7 for further investigation (Pcorrected = 2.08 × 10-10). This locus contained a 3 Mb run of homozygosity in the 12 mushroom ponies tested. Analysis of high throughput Illumina sequencing data from one mushroom Shetland pony compared to 87 genomes from horses of various breeds, uncovered a frameshift variant, p.Asp201fs, in the MFSD12 gene encoding the major facilitator superfamily domain containing 12 protein. This variant was perfectly concordant with phenotype in 96 Shetland Ponies (P = 1.15 × 10-22), was identified in the closely related Miniature Horse for which the mushroom phenotype is suspected to occur (fmu = 0.02), and was absent in 252 individuals from seven additional breeds not reported to have the mushroom phenotype. MFSD12 is highly expressed in melanocytes and variants in this gene in humans, mice, and dogs impact pigmentation. Given the role of MFSD12 in melanogenesis, we propose that p.Asp201fs is causal for the dilution observed in mushroom ponies.

Using the Five Domains Model to Assess the Adverse Impacts of Husbandry, Veterinary, and Equitation Interventions on Horse Welfare.

The aim of this study was to conduct a series of paper-based exercises in order to assess the negative (adverse) welfare impacts, if any, of common interventions on domestic horses across a broad range of different contexts of equine care and training. An international panel (with professional expertise in psychology, equitation science, veterinary science, education, welfare, equestrian coaching, advocacy, and community engagement; n = 16) met over a four-day period to define and assess these interventions, using an adaptation of the domain-based assessment model. The interventions were considered within 14 contexts: C1 Weaning; C2 Diet; C3 Housing; C4 Foundation training; C5 Ill-health and veterinary interventions (chiefly medical); C6 Ill-health and veterinary interventions (chiefly surgical); C7 Elective procedures; C8 Care procedures; C9 Restraint for management procedures; C10 Road transport; C11 Activity-competition; C12 Activity-work; C13 Activity-breeding females; and C14 Activity-breeding males. Scores on a 1-10 scale for Domain 5 (the mental domain) gathered during the workshop were compared with overall impact scores on a 1-10 scale assigned by the same panellists individually before the workshop. The most severe (median and interquartile range, IQR) impacts within each context were identified during the workshop as: C1 abrupt, individual weaning (10 IQR 1); C2 feeding 100% low-energy concentrate (8 IQR 2.5); C3 indoor tie stalls with no social contact (9 IQR 1.5); C4 both (i) dropping horse with ropes (9 IQR 0.5) and forced flexion (9 IQR 0.5); C5 long-term curative medical treatments (8 IQR 3); C6 major deep intracavity surgery (8.5 IQR 1); C7 castration without veterinary supervision (10 IQR 1); C8 both (i) tongue ties (8 IQR 2.5) and (ii) restrictive nosebands (8 IQR 2.5); C9 ear twitch (8 IQR 1); C10 both (i) individual transport (7.00 IQR 1.5) and group transport with unfamiliar companions (7 IQR 1.5); C11 both (i) jumps racing (8 IQR 2.5) and Western performance (8 IQR 1.5); C12 carriage and haulage work (6 IQR 1.5); C13 wet nurse during transition between foals (7.5 IQR 3.75); and C14 teaser horse (7 IQR 8). Associations between pre-workshop and workshop scores were high, but some rankings changed after workshop participation, particularly relating to breeding practices. Domain 1 had the weakest association with Domain 5. The current article discusses the use of the domain-based model in equine welfare assessment, and offers a series of assumptions within each context that future users of the same approach may make when assessing animal welfare under the categories reported here. It also discusses some limitations in the framework that was used to apply the model.

Advances in Diagnostics and Therapeutic Techniques in Breeding Behavior Disorders in Stallions.

Despite the suboptimal aspects of domestic breeding conditions compared with the natural conditions under which their reproductive behavior evolved, most domestic stallions can adapt to management and breeding programs. Most respond adequately or quickly learn to safely abide the restraint and direction of a human handler, and can adapt to changes in methods of breeding for semen collection. If not, the problems can range from inadequate or variable sexual interest and response to overenthusiastic or aggressive response beyond the ability of the handlers to safely direct and control. This article discusses veterinary evaluation as well as housing and handling strategies for addressing stallion breeding behavior problems.

Indenopyride derivative RTI-4587-073(l): a candidate for male contraception in stallions.

The objective of this study was to determine whether an indenopyridine derivative RTI-4587-073(l) was a good candidate for male contraception in horses. We hypothesized that a single administration of RTI-4587-073(l) causes significant suppression of testicular function in stallions without affecting sexual behavior. Three Miniature horse stallions received a single dose of 12.5 mg/kg RTI-4587-073(l) orally (group "treated"), whereas three other Miniature horse stallions received placebo only (group "control"). Semen was collected and evaluated from all stallions twice a week for three baseline weeks and 13 post-treatment weeks. Sexual behavior was video-recorded and analyzed. Testicular dimensions were measured using ultrasonography, and blood samples were drawn for endocrine evaluation once before treatment and once a week during the post-treatment period. Single administration of RTI-4587-073(l) caused severe oligoasthenozoospermia (low sperm number and low motility), shedding large numbers of immature germ cells in semen, and increased FSH concentrations in treated stallions. These effects were fully reversible within ∼71 days. However, libido and copulatory behavior remained unchanged throughout the entire experiment. We concluded that RTI-4587-073(l) was a promising candidate for male contraceptive in domestic stallions. Further research should be performed to test this compound for fertility control in wildlife and humans.

Ex vivo spontaneous generation of 19-norandrostenedione and nandrolone detected in equine plasma and urine.

19-Norandrostenedione (NAED) and nandrolone are anabolic-androgenic steroids (AASs). Nandrolone was regarded solely as a synthetic AAS until the 1980s when trace concentrations of apparently endogenous nandrolone were detected in urine samples obtained from intact male horses (stallions). Since then, its endogenous origin has been reported in boars and bulls; endogenous NAED and nandrolone have been identified in plasma and urine samples collected from stallions. More recently, however, it was suggested that NAED and nandrolone detected in urine samples from stallions are primarily artifacts due to the analytical procedure. The present study was undertaken to determine whether NAED and nandrolone detected in plasma and urine samples collected from stallions are truly endogenous or artifacts from sample processing. To answer this question, fresh plasma and urine samples from ≥8 stallions were analyzed for the two AASs, soon after collection, by liquid chromatography hyphenated to tandem mass spectrometry (LC-MS/MS). NAED and nandrolone were not detected in fresh plasma samples but detected in the same samples post storage. Concentrations of both AASs increased with storage time, and the increases were greater at a higher storage temperature (37°C versus 4°C, and ambient temperature versus 4°C). Although NAED was detected in some fresh stallion urine samples, its concentration (<407 pg/mL) was far lower (<0.4%) than that in the same samples post storage (at ambient temperature for 15 days). Nandrolone was not detected in most of fresh urine samples but detected in the same samples post storage. Based on these results, it is concluded that all NAED and nandrolone detected in stored plasma samples of stallions and most of them in the stored urine samples are not from endogenous origins but spontaneously generated during sample storage, most likely from spontaneous decarboxylation of androstenedione-19-oic acid and testosterone-19-oic acid. To our knowledge, it is the first time that all NAED and nandrolone detected in plasma of stallions and most of them detected in the urine have been shown to be spontaneously generated in vitro during sample storage. This finding would have significant implications with regard to the regulation of the two steroids in horse racing.

Physical, behavioral, endocrinologic, and cytogenetic evaluation of two Standardbred racehorses competing as mares with an intersex condition and high postrace serum testosterone concentrations.

CASE DESCRIPTION: 2 Standardbred racehorses that had been winning races while competing as mares underwent postrace drug testing and had serum testosterone concentrations above the acceptable limit for female racehorses. CLINICAL FINDINGS: Initial physical examinations by the referring veterinarian revealed ambiguous external genitalia and suspected intra-abdominally located testes leading to a preliminary diagnosis of male pseudohermaphroditism. Horses were referred for further evaluation of sex. Physical examination of the external genitalia confirmed the findings of the referring veterinarian. Transrectal palpation and ultrasonography revealed gonads with an ultrasonographic appearance of testes. On cytogenetic analysis, both horses were determined to have a 64,XY karyotype and 8 intact Y chromosome markers and 5 SRY gene markers, which were indicative of a genetic male and confirmed an intersex condition. Additionally, both horses had some male-type behavior and endocrinologic findings consistent with those of sexually intact males. TREATMENT AND OUTCOME: Taken together, these findings confirmed that both horses were male pseudohermaphrodites. Both horses returned to racing competition as males. CLINICAL RELEVANCE: As of October 1, 2008, the Pennsylvania Horse and Harness Racing Commissions implemented a postrace drug testing policy that included analysis of blood samples for anabolic and androgenic steroids and set maximum allowable concentrations of testosterone for racing geldings and females. Within 8 months of initiation of this drug testing policy, the 2 horses of this report were identified as having an intersex condition. This raises the possibility that intersex conditions may be more common in racing Standardbreds than was previously suspected.

Chromatin configuration and epigenetic landscape at the sex chromosome bivalent during equine spermatogenesis.

Pairing of the sex chromosomes during mammalian meiosis is characterized by the formation of a unique heterochromatin structure at the XY body. The mechanisms underlying the formation of this nuclear domain are reportedly highly conserved from marsupials to mammals. In this study, we demonstrate that in contrast to all eutherian species studied to date, partial synapsis of the heterologous sex chromosomes during pachytene stage in the horse is not associated with the formation of a typical macrochromatin domain at the XY body. While phosphorylated histone H2AX (γH2AX) and macroH2A1.2 are present as a diffuse signal over the entire macrochromatin domain in mouse pachytene spermatocytes, γH2AX, macroH2A1.2, and the cohesin subunit SMC3 are preferentially enriched at meiotic sex chromosome cores in equine spermatocytes. Moreover, although several histone modifications associated with this nuclear domain in the mouse such as H3K4me2 and ubH2A are conspicuously absent in the equine XY body, prominent RNA polymerase II foci persist at the sex chromosomes. Thus, the localization of key marker proteins and histone modifications associated with the XY body in the horse differs significantly from all other mammalian systems described. These results demonstrate that the epigenetic landscape and heterochromatinization of the equine XY body might be regulated by alternative mechanisms and that some features of XY body formation may be evolutionary divergent in the domestic horse. We propose equine spermatogenesis as a unique model system for the study of the regulatory networks leading to the epigenetic control of gene expression during XY body formation.

Chronic oral therapy with enalapril in normal ponies.

Enalapril is an angiotensin converting enzyme (ACE) inhibitor that is frequently used in human, feline and canine patients with cardiac disease. Its use has been associated with impotence in human patients. The purpose of this study was to evaluate if enalapril (0.5mg/kg PO, q24h) is likely to alter behavior in stallions and to assess its effect on ACE activity at the standard dose used in dogs and cats. Twelve pony stallions were evaluated by physical examination and echocardiography followed by treatment with enalapril (n=6) or placebo (n=6) for 2 months. After one month, blood was drawn and stored to evaluate ACE activity in the 2 groups. At the end of the study, repeat physical examination and echocardiography were performed. Physical examination, echocardiographic indices, and reproductive performance were unchanged and there was no suppression of ACE activity. Results of this study suggest that enalapril (0.5mg/kg PO, q24h) is either poorly absorbed in the horse or is inadequately converted to the active form of the drug, enalaprilat.

Practical review of self-mutilation in horses.

Self-mutilation in horses includes biting, stomping and kicking, rubbing, and lunging into objects. Based on the author's clinical experience, three distinct types of self-mutilation are proposed and described. Type I represents normal behavioral response to continuous or intermittent physical discomfort. Type II, seen in stallions and geldings, can be recognized as self-directed intermale aggression. The behavior includes the elements and order of the natural interactive sequence typical of encounters between two stallions, except that the stallion himself is the target of his intermale behavior. Type III involves a more quiet, often rhythmically repetitive or methodical behavioral sequence of a stereotypy, for example nipping at various areas of the body in a relatively invariant pattern, stomping, or kicking rhythmically against an object. The prevalence of the various types of self-mutilation in horses is not known. In one survey, results suggested that self-mutilation of one form or another has been observed in as many as 2% of domestic stallions. Among and between stallions, self-mutilation varies in frequency and intensity, and can reach levels that are fertility and/or life threatening. Careful evaluation of the horse's behavior is often necessary to distinguish the specific type. Type I self-mutilation, where physical discomfort is the root cause, can be eliminated by relieving the discomfort. For Types II and III, understanding of intermale interactive behavior of horses and the environmental factors that may trigger or exacerbate the self-mutilative form, can be useful in guiding humane management or behavior modification. Pharmacologic interventions may be a useful adjunct to management and nutritional changes.