Iron Horse Equine Reproduction Services

08/20/2026

Morphology better indicator than motility… S***m Motility actually has a 0.56 correlation to fertility yet so many put an emphasis on it.

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐒𝐞𝐦𝐞𝐧 𝐀𝐬𝐬𝐞𝐬𝐬𝐦𝐞𝐧𝐭 𝐚𝐬 𝐚 𝐅𝐞𝐫𝐭𝐢𝐥𝐢𝐭𝐲 𝐏𝐫𝐞𝐝𝐢𝐜𝐭𝐨𝐫 𝐢𝐧 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧𝐬

Accurate stallion semen assessment as a fertility predictor need not rely on expensive equipment. This study investigated whether basic light microscopy assessments of s***m motility, membrane integrity, and morphology could reliably distinguish fertile from sub-fertile stallions under field conditions.

Study Design:

• 24 frozen semen batches from 24 Arabian and Straight Egyptian Arabian stallions
• Semen frozen across Europe and the Middle East; used for artificial insemination in Doha, Qatar
• All straws standardized at 100 million s***m cells; thawed at 37°C for 1 minute
• Eosin-Nigrosin stain (Botuvital, Botupharma) used to assess membrane integrity and morphology under light microscopy
• 200 cells evaluated per sample; categorized as major, minor, total, and non-compensatory defects
• Mares inseminated once at ovulation; pregnancy confirmed by ultrasound at 14 days

Key Results:

• Major s***m pathologies, total pathologies, and non-compensatory defects were all significantly associated with pregnancy outcome (p

08/06/2026

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐓𝐞𝐬𝐭𝐢𝐜𝐮𝐥𝐚𝐫 𝐚𝐧𝐝 𝐄𝐩𝐢𝐝𝐢𝐝𝐲𝐦𝐚𝐥 𝐆𝐞𝐧𝐞 𝐄𝐱𝐩𝐫𝐞𝐬𝐬𝐢𝐨𝐧 𝐂𝐡𝐚𝐧𝐠𝐞𝐬 𝐢𝐧 𝐑𝐞𝐬𝐩𝐨𝐧𝐬𝐞 𝐭𝐨 𝐒𝐜𝐫𝐨𝐭𝐚𝐥 𝐇𝐞𝐚𝐭𝐢𝐧𝐠 𝐢𝐧 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧𝐬

Heat stress is a well-recognized cause of testicular & epididymal dysfunction, yet the underlying molecular events driving these changes remain poorly understood. This study used transcriptomic analysis to characterize early gene expression responses in testicular & epididymal tissues following acute scrotal insulation in stallions.

Study Design:
• 10 normos***mic adult light-breed stallions: control & scrotal insulation
• Scrotal insulation applied for 24 hours via insulation bag; stallions castrated immediately upon removal
• Tissue biopsies collected from te**es, epididymal head, body, & tail
• RNA sequencing & differential gene expression analysis performed; differentially expressed genes identified

Key Results:
• Differentially expressed genes in te**es, epididymal head, epididymal body, epididymal tail
• Te**es: S***matogenesis pathways downregulated; upregulated pathways associated with oxidant-antioxidant balance, immune activation (innate & adaptive), lipid & amino acid metabolism, & amyloid deposition
• Epididymal head: Dysregulation of s***matogenesis, energy metabolism, antigen presentation, & immune cell signaling
• Epididymal body: Differentially expressed genes associated with microtubule formation, s***m flagellum components, & cell motility
• Epididymal tail: Differentially expressed genes linked to energy metabolism & cell respiration

Conclusions:
• Acute scrotal heating rapidly dysregulates oxidant-antioxidant balance, energy metabolism, & immune homeostasis across testicular & epididymal tissues
• Region-specific gene expression patterns reflect distinct functional vulnerabilities within the reproductive tract
• Findings establish a molecular framework for understanding heat-induced reproductive dysfunction in stallions

(Ferrer M, Barletta M, Williams J, Moran K, Bilbao G, Bartolome J. 2025. Changes in equine testicular & epididymal homeostasis in response to scrotal heating. JEVS 145:105284 - https://doi.org/10.1016/j.jevs.2024.105284)

07/19/2026

We are travelling with our mobile unit to collect and freeze stallions in Quebec July 30-Aug 2. If anyone is interested in our services, pm us! Our portable phantom requires secure footing for 2’ stakes to be pounded into ground.

07/06/2026

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧 𝐃𝐢𝐬𝐦𝐨𝐮𝐧𝐭 𝐋𝐚𝐭𝐞𝐧𝐜𝐲 𝐚𝐧𝐝 𝐏𝐫𝐞𝐠𝐧𝐚𝐧𝐜𝐲 𝐎𝐮𝐭𝐜𝐨𝐦𝐞𝐬 𝐢𝐧 𝐓𝐡𝐨𝐫𝐨𝐮𝐠𝐡𝐛𝐫𝐞𝐝 𝐇𝐨𝐫𝐬𝐞𝐬

In Thoroughbred natural service breeding, dismount semen — residual urethral semen collected after copulation — is routinely used as a proxy for ej*****te quality. This study investigated whether the duration a stallion remains mounted post-ej*******on (stallion dismount latency) influences both dismount sample composition and pregnancy outcomes.

Study Design:

• 62 Thoroughbred stallions
• Dismount latency defined as time from ej*******on start to pe**le withdrawal
• Dismount samples analyzed for s***m concentration and motility parameters
• Pregnancy outcomes correlated with dismount latency using regression and one-tailed t-tests

Key Results:

• S***m concentration in dismount samples negatively correlated with dismount latency — shorter stallion dismount latency yielded higher-quality samples
• Total motility showed a similar negative trend with dismount latency, though not statistically significant
• Progressive motility, straightness, and average path velocity showed no significant correlation with dismount latency
• Stallion dismount latency was significantly longer in cycles resulting in pregnancy (11.1 vs. 10.2 seconds; p≤0.05)

Interpretation:

• Prolonged stallion dismount latency likely results in more s***m being deposited directly into the uterus rather than retained in the va**na
• Shorter dismount latency is associated with premature withdrawal, leaving more residual s***m in the dismount sample

Conclusions:

• Longer dismount latency improves pregnancy outcomes and should be encouraged through management strategies
• Paradoxically, higher-quality dismount samples are associated with poorer pregnancy rates
• Stallion dismount samples are unreliable proxies for ej*****te fertility and should be interpreted with caution.

(Medica A, Griffin R, Swegen A, Gibb Z. (2025) Prolonged dismount latency and its relationship with pregnancy outcomes in Thoroughbred horses. JEVS 145:105304 - abstract on-line at https://www.sciencedirect.com/science/article/abs/pii/S0737080624003101)

06/19/2026

💥ISSR Snippet!🐴 Post-Thaw S***m Quality & Blastocyst Production Following Intracytoplasmic S***m Injection in Mares

Background:
• ICSI is widely used to maximize semen availability from stallions with limited supply
• The relationship between standard frozen/thawed s***m quality measures & embryo production via ICSI remains poorly characterized

Study Design:
• Frozen/thawed semen from 44 stallions analyzed in a commercial ICSI program
• S***m assessed before & after swim-up selection for: total & progressive motility (subjective & computer-assisted), morphology, & DNA damage
• 485 in vitro-matured oocytes from 59 mares injected across 85 transva**nal aspiration cycles
• Stepwise logistic regression used to identify predictors of cleavage & blastocyst production

Program Efficiency:
• In vitro oocyte maturation rate: 64%
• Cleavage rate at day 5: 62%
• Blastocyst rate per injected oocyte: 29%
• Blastocyst rate per cleaved oocyte: 46%
• Total blastocysts produced: 139 (1.64 per session)

Key Results:
• Positive predictors of blastocyst production:
• Higher total motility before swim-up (subjective & computer-assisted)
• Higher percentage of morphologically normal s***matozoa
• Negative predictors of blastocyst production:
• Proximal cytoplasmic droplets after swim-up
• Coiled tails before swim-up
• Elevated s***m chromatin structure assay fragmentation index before swim-up
• No single parameter predicted cleavage rate

Conclusions:
• Pre-swim-up motility & normal morphology are the strongest positive indicators of ICSI success
• S***m structural defects & DNA damage are significant negative predictors
• Post-thaw s***m quality effect on ICSI is well-recognize & findings provide clinically applicable screening criteria assessable in standard laboratory settings

(Hernandez-Aviles C, Love CC, Ramirez-Agamez L. 2025. The relationship between post-thaw s***m quality & blastocyst production following Intracytoplasmic S***m Injection (ICSI) of in vitro-matured equine oocytes. JEVS 145:105293 - abstract on-line at https://www.sciencedirect.com/science/article/abs/pii/S0737080624002995)

06/19/2026

💥ISSR Snippet!🐴 Epididymal S***m Collection and Processing

Epididymal s***m collection and processing represent the last opportunity for genetic material rescue following sudden stallion death or emergency castration. This study evaluated multiple collection and processing variables across 142 samples to develop a standardized, practitioner-ready protocol.

Study Design:

• 142 samples collected from stallions undergoing elective orchiectomy (castration)
• Computer-assisted s***m analysis used for all kinematic assessments
• Variables tested:
•• Total versus partial intravenous anesthesia, with or without local lidocaine
•• Transport duration and temperature (5°C)
•• Harvesting technique: retrograde flush versus flotation
•• Two commercial extenders
•• Centrifugation effect
•• Refrigeration duration
•• Seasonality and age influence

Key Results:

• Partial intravenous anesthesia negatively affected motility compared to total intravenous anesthesia
• Local lidocaine had no effect on kinematic characteristics
• Motility declined during transport at 5°C, but viable s***matozoa were successfully recovered up to 72 hours
• Retrograde flush was superior to flotation for s***m harvesting
• Centrifugation did not improve any measured parameter
• Age and season significantly influenced motility and concentration

Conclusions:

• Epididymal s***matozoa maintain viable kinematic characteristics under general anesthesia and refrigerated transport
• Total intravenous anesthesia, retrograde flush, and avoidance of centrifugation are recommended
• Older stallions and those outside breeding season should be expected to yield reduced motility and concentration
• Results reflect pre-ejaculatory s***m characteristics and may not fully represent emergency castration scenarios

(Tripon TM, Crecan CM, Daradics Z, Morar IA. 2025. Equine epididymal s***matozoa: A practical guide to collection, processing, and laboratory techniques. JEVS 145:105328 - abstract on-line at https://www.sciencedirect.com/science/article/abs/pii/S0737080624003344)

05/27/2026

https://www.facebook.com/share/p/1Cc6P2KREC/

💥ISSR Snippet!🐴 Predicting Breeding Soundness in Pre-, Peri- and Postpubertal Colts

Background:
• The study aimed to identify parameters for predicting breeding soundness in colts at the youngest possible age
• Rearing colts for breeding is costly; early prediction of future fertility has significant economic value

Study Design:
• 46 Warmblood colts examined at approximately 6 months, 20 months, and 30 months of age
• Assessments included: body condition scoring, weight, and testicular palpation, ultrasound and volume measurement
• Blood sampling before and after human chorionic gonadotropin stimulation (5,000 IU intravenously)
• Hormones measured: anti-Müllerian hormone (basal) and testosterone (at 0, 2, 24, and 72 hours post-stimulation)
• 12 stallions at 2.5 years were evaluated for s***m quality; grouped by testicular volume and palpation findings

Key Results:
• No significant difference in morphologically normal or progressively motile s***matozoa between groups
• Stallions with small te**es showed lower membrane-intact s***matozoa and higher acrosome reaction rates
• Body condition score positively correlated with progressively motile s***matozoa (r=0.765, p

05/22/2026

New open-access review — worth a read!

The equine reproductive tract is not just about hormones, anatomy and timing… microbes may also have a say.

In this open-access review, Pelenė, Šiukščius, Nainienė, Merkelytė and Šveistienė explore what is currently known about the equine reproductive microbiota in both mares and stallions: from va**nal and uterine microbial communities to seminal microbiota, dysbiosis, endometritis, semen quality, and fertility.

The review highlights an important shift in perspective: the equine uterus is no longer viewed simply as “sterile vs infected”. Instead, reproductive health may depend on a delicate balance between microbes, host defenses, hormones and clinical context.

A key take-home message: microbiota data are promising, but they must be interpreted carefully in conjunction with clinical examination, cytology, culture, and reproductive history.

An interesting read for anyone working in equine reproduction, fertility and reproductive health.

Open access article:
https://www.mdpi.com/2076-2615/16/9/1414

04/27/2026