Preliminary investigation of potential links between pigmentation variants and opioid analgesic effectiveness in horses during cerebrospinal fluid centesis.

BACKGROUND: The pleiotropic effects of the melanocortin system show promise in overcoming limitations associated with large variations in opioid analgesic effectiveness observed in equine practice. Of particular interest is variation in the melanocortin-1-receptor (MC1R) gene, which dictates pigment type expression through its epistatic interaction with the agouti signalling protein (ASIP) gene. MC1R has previously been implicated in opioid efficacy in other species; however, this relationship is yet to be explored in horses. In this study, analgesic effectiveness was scored (1-3) based on noted response to dura penetration during the performance of cerebrospinal fluid centisis after sedation and tested for association with known genetic regions responsible for pigmentation variation in horses. RESULTS: The chestnut phenotype was statistically significant (P < 0.05) in lowering analgesic effectiveness when compared to the bay base coat colour. The 11bp indel in ASIP known to cause the black base coat colour was not significant (P>0.05); however, six single nucleotide polymorphisms (SNPs) within the genomic region encoding the ASIP gene and one within MC1R were identified as being nominally significant (P<0.05) in association with opioid analgesic effectiveness. This included the location of the known e MC1R variant resulting in the chestnut coat colour. CONCLUSIONS: The current study provides promising evidence for important links between pigmentation genes and opioid effectiveness in horses. The application of an easily identifiable phenotype indicating variable sensitivity presents a promising opportunity for accessible precision medicine in the use of analgesics and warrants further investigation.

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy in Gypsy Vanner horses.

BACKGROUND: Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disease that primarily affects young, genetically predisposed horses that are deficient in vitamin E. Equine NAD/EDM has not previously been documented in Gypsy Vanner horses (GVs). OBJECTIVES: To evaluate: (1) the clinical phenotype, blood vitamin E concentrations before and after supplementation and pedigree in a cohort of GV horses with a high prevalence of neurologic disease suspicious for eNAD/EDM and (2) to confirm eNAD/EDM in GVs through postmortem evaluation. ANIMALS: Twenty-six GVs from 1 farm in California and 2 cases from the Midwestern U.S. METHODS: Prospective observational study on Californian horses; all 26 GVs underwent neurologic examination. Pre-supplementation blood vitamin E concentration was assessed in 17- GVs. Twenty-three were supplemented orally with 10 IU/kg of liquid RRR-alpha-tocopherol once daily for 28 days. Vitamin E concentration was measured in 23 GVs after supplementation, of which 15 (65%) had pre-supplementation measurements. Two clinically affected GVs from California and the 2 Midwestern cases had necropsy confirmation of eNAD/EDM. RESULTS: Pre-supplementation blood vitamin E concentration was ≤2.0 µg/mL in 16/17 (94%) of GVs from California. Post-supplementation concentration varied, with a median of 3.39 µg/mL (range, 1.23-13.87 µg/mL), but only 12/23 (52%) were normal (≥3.0 µg/mL). Normalization of vitamin E was significantly associated with increasing age (P = .02). Euthanized horses (n = 4) had eNAD/EDM confirmed at necropsy. CONCLUSIONS AND CLINICAL IMPORTANCE: GVs could have a genetic predisposition to eNAD/EDM. Vitamin E supplementation should be considered and monitored in young GVs.

Clinicopathological and pedigree investigation of a novel spinocerebellar neurological disease in juvenile Quarter Horses in North America.

BACKGROUND: In 2020, a novel neurologic disease was observed in juvenile Quarter Horses (QHs) in North America. It was unknown if this was an aberrant manifestation of another previously described neurological disorder in foals, such as equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM). HYPOTHESIS/OBJECTIVES: To describe the clinical findings, outcomes, and postmortem changes with Equine Juvenile Spinocerebellar Ataxia (EJSCA), differentiate the disease from other similar neurological disorders, and determine a mode of inheritance. ANIMALS: Twelve neurologically affected QH foals and the dams. METHODS: Genomic DNA was isolated and pedigrees were manually constructed. RESULTS: All foals (n = 12/12) had a history of acute onset of neurological deficits with no history of trauma. Neurological deficits were characterized by asymmetrical spinal ataxia, with pelvic limbs more severely affected than thoracic limbs. Clinicopathological abnormalities included high serum activity of gamma-glutamyl transferase and hyperglycemia. All foals became recumbent (median, 3 days: [0-18 days]), which necessitated humane euthanasia (n = 11/12, 92%; the remaining case was found dead). Histological evaluation at postmortem revealed dilated myelin sheaths and digestion chambers within the spinal cord, most prominently in the dorsal spinocerebellar tracts. Pedigree analysis revealed a likely autosomal recessive mode of inheritance. CONCLUSIONS AND CLINICAL IMPORTANCE: EJSCA is a uniformly fatal, rapidly progressive, likely autosomal recessive neurological disease of QHs <1 month of age in North America that is etiologically distinct from other clinically similar neurological disorders. Once the causative variant for EJSCA is validated, carriers can be identified through genetic testing to inform breeding decisions.

Validation of a serum ELISA test for cyathostomin infection in equines.

Cyathostomins are ubiquitous equine nematodes. Infection can result in larval cyathostominosis due to mass larval emergence. Although faecal egg count (FEC) tests provide estimates of egg shedding, these correlate poorly with burden and provide no information on mucosal/luminal larvae. Previous studies describe a serum IgG(T)-based ELISA (CT3) that exhibits utility for detection of mucosal/luminal cyathostomins. Here, this ELISA is optimised/validated for commercial application using sera from horses for which burden data were available. Optimisation included addition of total IgG-based calibrators to provide standard curves for quantification of antigen-specific IgG(T) used to generate a CT3-specific 'serum score' for each horse. Validation dataset results were then used to assess the optimised test's performance and select serum score cut-off values for diagnosis of burdens above 1000, 5000 and 10,000 cyathostomins. The test demonstrated excellent performance (Receiver Operating Characteristic Area Under the Curve values >0.9) in diagnosing infection, with >90% sensitivity and >70% specificity at the selected serum score cut-off values. CT3-specific serum IgG(T) profiles in equines in different settings were assessed to provide information for commercial test use. These studies demonstrated maternal transfer of CT3-specific IgG(T) in colostrum to newborns, levels of which declined before increasing as foals consumed contaminated pasture. Studies in geographically distinct populations demonstrated that the proportion of horses that reported as test positive at a 14.37 CT3 serum score (1000-cyathostomin threshold) was associated with parasite transmission risk. Based on the results, inclusion criteria for commercial use were developed. Logistic regression models were developed to predict probabilities that burdens of individuals are above defined thresholds based on the reported serum score. The models performed at a similar level to the serum score cut-off approach. In conclusion, the CT3 test provides an option for veterinarians to obtain evidence of low cyathostomin burdens that do not require anthelmintic treatment and to support diagnosis of infection.

Genetic polymorphisms in vitamin E transport genes as determinants for risk of equine neuroaxonal dystrophy.

BACKGROUND: Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder associated with vitamin E deficiency. In humans, polymorphisms in genes involved in vitamin E uptake and distribution determines individual vitamin E requirements. HYPOTHESIS/OBJECTIVES: Genetic polymorphisms in genes involved in vitamin E metabolism would be associated with an increased risk of eNAD/EDM in Quarter Horses (QHs). ANIMALS: Whole-genome sequencing: eNAD/EDM affected (n = 9, postmortem [PM]-confirmed) and control (n = 32) QHs. VALIDATION: eNAD/EDM affected (n = 39, 23-PM confirmed) and control (n = 68, 7-PM confirmed) QHs. Allele frequency (AF): Publicly available data from 504 horses across 47 breeds. METHODS: Retrospective, case control study. Whole-genome sequencing was performed and genetic variants identified within 28 vitamin E candidate genes. These variants were subsequently genotyped in the validation cohort. RESULTS: Thirty-nine confirmed variants in 15 vitamin E candidate genes were significantly associated with eNAD/EDM (P < .01). In the validation cohort, 2 intronic CD36 variants (chr4:726485 and chr4:731082) were significantly associated with eNAD/EDM in clinical (P = 2.78 × 10-4 and P = 4 × 10-4 , respectively) and PM-confirmed cases (P = 6.32 × 10-6 and 1.04 × 10-5 , respectively). Despite the significant association, variant AFs were low in the postmortem-confirmed eNAD/EDM cases (0.22-0.26). In publicly available equine genomes, AFs ranged from 0.06 to 0.1. CONCLUSIONS AND CLINICAL IMPORTANCE: Many PM-confirmed cases of eNAD/EDM were wild-type for the 2 intronic CD36 SNPs, suggesting either a false positive association or genetic heterogeneity of eNAD/EDM within the QH breed.

Additional evidence supports GRM6 p.Thr178Met as a cause of congenital stationary night blindness in three horse breeds.

Congenital stationary night blindness (CSNB) is an ocular disorder characterized by nyctalopia. An autosomal recessive missense mutation in glutamate metabotropic receptor 6 (GRM6 c.533C>T, p.(Thr178Met)), called CSNB2, was previously identified in one Tennessee Walking Horse and predicted to reduce binding affinity of the neurotransmitter glutamate, impacting the retinal rod ON-bipolar cell signaling pathway. Thus, the first aim was to identify the allele frequency (AF) of CSNB2 in breeds with reported cases of CSNB and breeds closely related to the Tennessee Walking Horse. The second aim was to perform ocular examinations in multiple breeds to confirm the link between genotype and CSNB phenotype. In evaluating 3518 horses from 14 breeds, the CSNB2 allele was identified in nine previously unreported breeds. The estimated AF was highest in pacing Standardbreds (0.17) and lowest in American Quarter Horses (0.0010). Complete ophthalmic examinations and electroretinograms (ERG) were performed on 19 horses from three breeds, including one CSNB2 homozygote from each breed. All three CSNB2/CSNB2 horses had an electronegative ERG waveform under scotopic light conditions consistent with CSNB. The remaining 16 horses (seven CSNB2/N and nine N/N) had normal scotopic ERG results. All horses had normal photopic ERGs. This study provides additional evidence that GRM6 c.533C>T homozygosity is likely causal to CSNB in Tennessee Walking Horses, Standardbreds, and Missouri Fox Trotting Horses. Genetic testing is recommended for breeds with the CSNB2 allele to limit the production of affected horses. This study represents the largest across-breed identification of CSNB in the horse and suggests that this disorder is likely underdiagnosed.

Functional annotation of the animal genomes: An integrated annotation resource for the horse.

The genomic sequence of the horse has been available since 2009, providing critical resources for discovering important genomic variants regarding both animal health and population structures. However, to fully understand the functional implications of these variants, detailed annotation of the horse genome is required. Due to the limited availability of functional data for the equine genome, as well as the technical limitations of short-read RNA-seq, existing annotation of the equine genome contains limited information about important aspects of gene regulation, such as alternate isoforms and regulatory elements, which are either not transcribed or transcribed at a very low level. To solve above problems, the Functional Annotation of the Animal Genomes (FAANG) project proposed a systemic approach to tissue collection, phenotyping, and data generation, adopting the blueprint laid out by the Encyclopedia of DNA Elements (ENCODE) project. Here we detail the first comprehensive overview of gene expression and regulation in the horse, presenting 39,625 novel transcripts, 84,613 candidate cis-regulatory elements (CRE) and their target genes, 332,115 open chromatin regions genome wide across a diverse set of tissues. We showed substantial concordance between chromatin accessibility, chromatin states in different genic features and gene expression. This comprehensive and expanded set of genomics resources will provide the equine research community ample opportunities for studies of complex traits in the horse.

Cerebrospinal fluid and serum proteomic profiles accurately distinguish neuroaxonal dystrophy from cervical vertebral compressive myelopathy in horses.

BACKGROUND: Cervical vertebral compressive myelopathy (CVCM) and equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) are leading causes of spinal ataxia in horses. The conditions can be difficult to differentiate, and there is currently no diagnostic modality that offers a definitive antemortem diagnosis. OBJECTIVE: Evaluate novel proteomic techniques and machine learning algorithms to predict biomarkers that can aid in the antemortem diagnosis of noninfectious spinal ataxia in horses. ANIMALS: Banked serum and cerebrospinal fluid (CSF) samples from necropsy-confirmed adult eNAD/EDM (n = 47) and CVCM (n = 25) horses and neurologically normal adult horses (n = 45). METHODS: . A subset of serum and CSF samples from eNAD/EDM (n = 5) and normal (n = 5) horses was used to evaluate the proximity extension assay (PEA). All samples were assayed by PEA for 368 neurologically relevant proteins. Data were analyzed using machine learning algorithms to define potential diagnostic biomarkers. RESULTS: Of the 368 proteins, 84 were detected in CSF and 146 in serum. Eighteen of 84 proteins in CSF and 30/146 in serum were differentially abundant among the 3 groups, after correction for multiple testing. Modeling indicated that a 2-protein test using CSF had the highest accuracy for discriminating among all 3 groups. Cerebrospinal fluid R-spondin 1 (RSPO1) and neurofilament-light (NEFL), in parallel, predicted normal horses with an accuracy of 87.18%, CVCM with 84.62%, and eNAD/EDM with 73.5%. MAIN LIMITATIONS: Cross-species platform. Uneven sample size. CONCLUSIONS AND CLINICAL IMPORTANCE: Proximity extension assay technology allows for rapid screening of equine biologic matrices for potential protein biomarkers. Machine learning analysis allows for unbiased selection of highly accurate biomarkers from high-dimensional data.

Identification of putative orthologs of clinically relevant antimicrobial peptides in the equine ocular surface and amniotic membrane.

OBJECTIVES: This study aimed to define the antimicrobial peptide (AMP) expression pattern of the equine ocular surface and amniotic membrane using a targeted qPCR approach and 3'Tag-sequencing. It will serve as a reference for future studies of ocular surface innate immunity and amniotic membrane therapies. PROCEDURES: A targeted qPCR approach was used to investigate the presence of orthologs for three of the most highly expressed beta-defensins (DEFB1, DEFB4B, and DEFB103A) of the human ocular surface and amniotic membrane in equine corneal epithelium, conjunctiva, and amniotic membrane. 3'Tag-sequencing was performed on RNA from one sample of corneal epithelium, conjunctiva, and amniotic membrane to further characterize their AMP expression. RESULTS: Equine corneal epithelium, conjunctiva, and amniotic membrane expressed DEFB1, DEFB4B, and DEFB103A. DEFB103A was expressed at the highest amounts in corneal epithelium, while DEFB4B was most highly expressed in conjunctiva and amniotic membrane. 3'Tag-sequencing from all three tissues confirmed these findings and identified expression of five additional beta-defensins, 11 alpha-defensins and two cathelicidins, with the alpha-defensins showing higher normalized read counts than the beta-defensins. CONCLUSIONS: This study identified AMP expression in the equine cornea and conjunctiva, suggesting that they play a key role in the protection of the equine eye, similar to the human ocular surface. We also determined that equine amniotic membrane expresses a substantial number of AMPs suggesting it could potentiate an antimicrobial effect as a corneal graft material. Future studies will focus on defining the antimicrobial activity of these AMPs and determining their role in microbial keratitis.

Vitamin E depletion is associated with subclinical axonal degeneration in juvenile horses.

BACKGROUND: Phosphorylated neurofilament heavy, a marker of neuroaxonal damage, is increased in horses with equine neuroaxonal dystrophy. However, the temporal dynamics of this biomarker during the post-natal risk period are not understood. OBJECTIVE: To measure serum and cerebrospinal fluid phosphorylated neurofilament heavy concentrations in juvenile foals across the post-natal window of susceptibility for equine neuroaxonal dystrophy. STUDY DESIGN: Case-control in vivo experimental study. METHODS: Concentrations of phosphorylated neurofilament heavy were measured using frozen serum and cerebrospinal fluid collected from 13 foals raised in a vitamin E deficient environment from 1 to 6 months of age. Four of these foals were produced by equine neuroaxonal dystrophy-affected dams, developed clinical signs consistent with equine neuroaxonal dystrophy and had a diagnosis confirmed by histopathology. The remaining nine foals, produced by healthy mares, were vitamin E depleted and remained clinically healthy. An additional cohort of foals, produced by healthy mares, were supplemented with vitamin E (α-tocopherol; α-TOH) from birth and sampled similarly. RESULTS: Serum α-TOH concentrations were significantly higher in vitamin E supplemented healthy foals. Serum phosphorylated neurofilament heavy concentrations did not differ significantly between groups at any time point. Cerebrospinal fluid phosphorylated neurofilament heavy concentrations increased with age in healthy vitamin E depleted foals (p < 0.001); an effect that was not observed in healthy vitamin E supplemented foals. MAIN LIMITATIONS: A genetically susceptible cohort supplemented with vitamin E was not available for comparison. CONCLUSION: We demonstrate that vitamin E depletion may elevate cerebrospinal fluid phosphorylated neurofilament heavy in otherwise healthy juvenile foals by 6 months of age. We highlight an important cofactor to consider when interpreting cerebrospinal fluid phosphorylated neurofilament heavy concentrations in juvenile horses.

Serum and cerebrospinal fluid phosphorylated neurofilament heavy protein concentrations in equine neurodegenerative diseases.

BACKGROUND: Currently, there is little information regarding the concentrations of phosphorylated neurofilament heavy protein (pNfH) in the serum and cerebrospinal fluid (CSF) of horses with neurodegenerative diseases. Specifically, pNfH concentrations have not yet been evaluated in horses with equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM). OBJECTIVES: To determine pNfH concentrations using a commercial enzyme-linked immunosorbent assay (ELISA) in serum and CSF from control horses and horses with eNAD/EDM, cervical vertebral compressive myelopathy (CVCM) and Shivers. STUDY DESIGN: Case-control study using biobanked samples from diseased horses and prospective or biobanked samples from control horses. METHODS: The pNfH ELISA was performed on samples from horses diagnosed with eNAD/EDM (n = 64), CVCM (n = 26) and Shivers (n = 9) and 51 neurologically normal control horses. RESULTS: Median and 95% confidence interval (CI) serum pNfH concentrations in control, CVCM, and eNAD/EDM horses were 0.08 ng/mL (0.07-0.15), 0.07 ng/mL (0.07-0.15) and 0.07 ng/mL (0.07-1.13), respectively. Serum pNfH concentrations were below the limit of detection (<0.07 ng/mL) for all Shivers horses. CSF pNfH concentrations in control, CVCM-, eNAD/EDM- and Shivers-affected horses were 1.26 ng/mL (1.06-1.5), 3.07 ng/mL (1.15-29.9), 1.78 ng/mL (1.5-2.28) and 1.39 ng/mL (0.74-3.89), respectively. CSF pNfH concentrations were significantly higher in CVCM (P = .001) and eNAD/EDM (P  = .01) affected horses compared to control horses. Serum pNfH concentrations >1 ng/mL were significantly associated with eNAD/EDM (P = .01) with only 12% sensitivity but 99% specificity. CSF pNfH concentrations >3 ng/mL were significantly associated with CVCM (P = .0002), with 50% sensitivity and 86% specificity. MAIN LIMITATIONS: A limited number of control horses tested were <1 year of age. CONCLUSIONS: Serum pNfH concentrations are specifically increased (>1 ng/mL) in some horses with eNAD/EDM. Increased CSF pNfH concentrations (>3 ng/mL) can be observed with eNAD/EDM or CVCM.

Increased α-tocopherol metabolism in horses with equine neuroaxonal dystrophy.

BACKGROUND: Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder associated with a vitamin E deficiency within the first year of life. Vitamin E consists of 8 isoforms metabolized by the CYP4F2 enzyme. No antemortem diagnostic test currently exists for eNAD/EDM. HYPOTHESIS/OBJECTIVES: Based on the association of α-tocopherol deficiency with the development of eNAD/EDM, we hypothesized that the rate of α-tocopherol, but not γ-tocopherol or tocotrienol metabolism, would be increased in eNAD/EDM-affected horses. ANIMALS: Vitamin E metabolism: Proof of concept (POC) study; eNAD/EDM-affected (n = 5) and control (n = 6) horses. Validation study: eNAD/EDM-affected Quarter Horses (QHs; n = 6), cervical vertebral compressive myelopathy affected (n = 6) horses and control (n = 29) horses. CYP4F2 expression and copy number: eNAD/EDM-affected (n = 12) and age- and sex-matched control (n = 11-12) horses. METHODS: The rates of α-tocopherol/tocotrienol and γ-tocopherol/tocotrienol metabolism were assessed in equine serum (POC and validation) and urine (POC only) using liquid chromatography tandem mass spectrometry (LC-MS/MS). Quantitative reverse-transcriptase PCR (qRT-PCR) and droplet digital (dd)-PCR were used to assay expression and genomic copy number of a CYP4F2 equine ortholog. RESULTS: Metabolic rate of α-tocopherol was increased in eNAD/EDM horses (POC,P < .0001; validation, P = .03), with no difference in the metabolic rate of γ-tocopherol. Horses with eNAD/EDM had increased expression of the CYP4F2 equine orthologue (P = .02) but no differences in copy number. CONCLUSIONS AND CLINICAL IMPORTANCE: Increased α-tocopherol metabolism in eNAD/EDM-affected QHs provides novel insight into alterations in vitamin E processing in eNAD/EDM and highlights the need for high-dose supplementation to prevent the clinical phenotype in genetically susceptible horses.

Generation of a Biobank From Two Adult Thoroughbred Stallions for the Functional Annotation of Animal Genomes Initiative.

Following the successful creation of a biobank from two adult Thoroughbred mares, this study aimed to recapitulate sample collection in two adult Thoroughbred stallions as part of the Functional Annotation of the Animal Genome (FAANG) initiative. Both stallions underwent thorough physical, lameness, neurologic, and ophthalmic (including electroretinography) examinations prior to humane euthanasia. Epididymal sperm was recovered from both stallions immediately postmortem and cryopreserved. Aseptically collected full thickness skin biopsies were used to isolate, culture and cryopreserve dermal fibroblasts. Serum, plasma, cerebrospinal fluid, urine, and gastrointestinal content from various locations were collected and cryopreserved. Under guidance of a board-certified veterinary anatomic pathologist, 102 representative tissue samples were collected from both horses. Whole tissue samples were flash-frozen and prioritized tissues had nuclei isolated and cryopreserved. Spatially contemporaneous samples of each tissue were submitted for histologic examination. Antemortem and gross pathologic examination revealed mild abnormalities in both stallions. One stallion (ECA_UCD_AH3) had unilateral thoracic limb lameness and bilateral chorioretinal scars. The second stallion (ECA_UCD_AH4) had subtle symmetrical pelvic limb ataxia, symmetrical prostatomegally, and moderate gastrointestinal nematodiasis. DNA from each was whole-genome sequenced and genotyped using the GGP Equine 70K SNP array. The genomic resources and banked biological samples from these animals augments the existing resource available to the equine genomics community. Importantly we may now improve the resolution of tissue-specific gene regulation as affected by sex, as well as add sex-specific tissues and gametes.

Overgrowth Syndrome.

Large offspring syndrome (LOS) is a fetal overgrowth condition in bovines most often observed in offspring conceived with the use of assisted reproductive technologies (ART). Phenotypes observed in LOS include, overgrowth, enlarged tongues, umbilical hernias, muscle and skeleton malformations, abnormal organ growth and placental development. Although LOS cases have only been reported to be associated with ART, fetal overgrowth can occur spontaneously in cattle (S-LOS). S-LOS refers to oversized calves that are born at normal gestation lengths. ART-induced LOS has been characterized as an epigenetic syndrome, more specifically, a loss-of-imprinting condition. We propose that S-LOS is also a loss-of-imprinting condition.

Effects of flunixin meglumine on postponement of ovulation in mares.

OBJECTIVE To evaluate use of flunixin meglumine as a treatment to postpone ovulation in mares, mare fertility after flunixin meglumine treatment during estrous cycles, and effects of flunixin meglumine on function of the corpus luteum after ovulation. ANIMALS 13 healthy mares. PROCEDURES A single-blinded, placebo-controlled, crossover study was conducted. Flunixin meglumine (1.1 mg/kg, IV, q 24 h) or lactated Ringer solution (placebo treatment) was administered for 2 days to mares with a dominant follicle (≥ 35 mm in diameter) and behavioral signs of estrus. Mares then were bred by artificial insemination. Number of days to ovulation from initial detection of a follicle ≥ 30 mm in diameter, uterine edema score, and pregnancy were determined by ultrasonography; the examiner was unaware of the treatment of each mare. Serum progesterone concentrations were evaluated 5 and 12 days after ovulation by use of radioimmunoassay. RESULTS Data were available for 45 estrus cycles of the 13 mares. Number of days to ovulation from initial detection of a follicle ≥ 30 mm was not significantly affected by administration of flunixin meglumine versus the placebo. Per-cycle pregnancy rate was not significantly different between flunixin meglumine (20/24 [83%] breedings) and the placebo (13/19 [68%] breedings). Flunixin meglumine did not significantly affect behavioral signs of estrus, uterine edema, or serum progesterone concentrations. CONCLUSIONS AND CLINICAL RELEVANCE Findings did not support the use of flunixin meglumine to postpone ovulation in mares.

Efficacy and outcome of foaling augmented with oxytocin using mammary calcium and pH criteria to guide the timing of augmentation.

Augmentation of parturition can be used to advance labor in mares to occur at a time when personnel is available to assist if necessary. We performed a retrospective study to determine the efficacy and safety of augmentation to manage foalings. Augmentation was performed with 3 IU oxytocin i.v. when mammary calcium concentrations were ≥250 ppm, mammary secretion pH ≤ 6.5, and the mare showed impending signs of parturition. Augmented parturitions (n = 19) were compared with three different control groups. The three control groups were: 1) Time Match control (n = 37) which were non-augmented foalings in the barn during the same time period; 2) Mare Match control (n = 32) which were the non-augmented parturitions of the augmented mares in previous years; and 3) Historic Match control (n = 165) consisted of foalings that occurred from 2006 to 2016 in the facility. All augmented mares foaled within two h with an average of 44 min (range 20-75) after oxytocin injection. The interval between foaling and the foal standing was shorter in augmented parturitions compared with historic match controls. The interval between foaling and the foal nursing was longer with augmented parturitions compared with time match and historic match controls. Duration of fetal membrane retention was not different between all groups. Augmentation of imminent parturition is potentially a safe and effective treatment for mares and foals. Implementation of augmentation as a routine procedure may increase the likelihood of enteral administration of colostrum to foals.

Tumor collision of uterine adenocarcinoma and leiomyosarcoma in a goat.

An aged mixed-breed goat doe was presented with a 9-mo history of serosanguineous vaginal discharge. Vaginal speculum examination revealed serosanguineous discharge but otherwise no abnormalities. Transrectal ultrasonography showed normal ovaries and multifocal cystic lesions within the uterus. Ovariohysterectomy was recommended because of a strong suspicion of neoplasia. Multiple, non-resectable masses were noted in and around the uterus intraoperatively, and euthanasia was elected. Autopsy revealed multiple masses within the uterus, cervix, and lung parenchyma. Histologically, the masses within the uterus represented a likely collision tumor of primary adenocarcinoma and leiomyosarcoma. Our report highlights the importance of obtaining biopsy samples of all masses because the lesions described showed significantly different biological behavior. This information is vital to guide treatment and prognosis.