Effects of pulsed electromagnetic therapy on the major hematological and biochemical parameters in horses

Abstract

Pulsed electromagnetic field (PEMF) therapy, a commonly used supplementary treatment in the horse industry, shows promise in enhancing circulation, reducing inflammation, and supporting cellular repair; however, its effects on equine physiology remain unclear. Limited research and inconsistent protocols create uncertainty about its efficacy and safety in horses. Our study evaluates the short-term effects of PEMF on hematological and biochemical parameters in horses. Five active sport horses underwent PEMF therapy for five consecutive days using a full-body blanket at specific frequencies. Blood samples were collected both before and after treatment to assess 72 hematological, biochemical, and endocrine parameters. Pre- and post-treatment data for each parameter were analyzed and compared. While most hematological parameters remained stable, significant alterations were observed in reticulocyte and platelet counts, as well as hemoglobin levels. Blood biochemistry exhibited greater variability, with notable changes in plasma proteins, bilirubin, uric acid, creatine kinase, creatinine, liver enzymes, and iron-binding capacity. No significant changes were observed in cortisol or thyroxine levels. According to our exploratory data, whole-body PEMF therapy showed no detectable adverse effects over five days on health or stress response. While most parameters remained unchanged, significant biochemical and hematological changes suggest that PEMF may support the animals and warrant further research on its mechanisms and applications.

INTRODUCTION

Pulsed electromagnetic field (PEMF) therapy is a non-invasive treatment modality and a form of alternative physiotherapy that utilizes electromagnetic fields to promote healing and improve cellular function. It delivers low-frequency electromagnetic pulses to the body, creating a dynamic environment for cellular activity. It is believed to enhance circulation, reduce inflammation, and support cellular repair processes [23, 27, 32]. In veterinary medicine, its application is gaining attention as a complementary approach for treating various musculoskeletal and soft tissue injuries in animals.

PEMF therapy has shown promising physiological effects across a wide range of biological systems, with evidence mainly coming from in vitro models and in vivo rodent experiments. PEMF influences ion movement across cell membranes, promoting cellular interactions, proliferation, differentiation, and energy production; it enhances vasodilation, blood flow, and the release of growth factors and cytokines, thereby supporting tissue repair, reducing inflammation, and improving cellular functions [9, 19, 29, 47, 54, 55, 64, 79].

Rodent studies have shown that low-frequency PEMF improves microcirculation, thereby enhancing oxygenation and nutrient delivery, particularly in tissues such as the skin and gastrointestinal tract [10, 28, 45, 61, 62]. As a result of these processes, venous return and waste removal are enhanced, which indirectly supports cellular metabolism [37]. Besides its circulatory functions, the therapeutic applications of PEMF in bone regeneration have also been extensively studied. It amplifies osteogenic activity, enhances calcium deposition, and increases collagen synthesis [12, 14]. Additionally, PEMF upregulates critical markers such as alkaline phosphatase, which play a key role in fracture repair and maintaining bone integrity [13, 25, 81]. These cardiovascular and bone benefits make PEMF application an ideal supplementary therapy in sports medicine.

PEMF therapy is increasingly used in equine practice for its potential to support physiological functions related to athletic performance and recovery. In horses, many studies focus on the musculoskeletal system. Early reviews demonstrated benefits to circulation and tissue repair [5]. Experimental work with equine cancellous bone grafts showed enhanced graft incorporation with PEMF [38]. In tendon research, Watkins et al. [78] examined surgically created defects in the equine superficial digital flexor tendon and found that PEMF delayed the maturation of repair tissue, with some shift in collagen-type transformation, and caused morphological reorganization differences. More recently, PEMF (22 Hz) was applied to equine hooves, reporting a trend toward increased sole depth in distal regions over 30 days, although results were modest [44]. Clinical field data evaluated the short-term effects of a single PEMF session on gait, lameness, and stress in exercising horses, noting improvements in gait quality and stress markers, though lameness scores did not change significantly [56]. Systematic reviews of electrotherapy and complementary methods in sport and companion animals further underscore PEMF’s potential to reduce inflammation, improve healing, and support recovery. Still, they consistently highlight the variability in study designs, treatment parameters, and outcome measures [8, 34].

Beyond equine research, mammalian and human model studies demonstrate that PEMF can acutely enhance microcirculation via nitric-oxide–mediated vasodilation (e.g., in brain tissue), improve blood rheology and capillary perfusion, and modulate inflammatory pathways in connective tissues [1, 10, 18, 43]. Large-animal cross-species coherence is observed in the following: equine tendon explants show reduced expression of pro-inflammatory mediators and improved matrix activity under PEMF exposure, while bovine cartilage and tendon models demonstrate anti-inflammatory and anabolic responses, consistent with improved connective tissue repair [74].

Overall, the evidence from equine and non-equine studies strengthens the biological plausibility of PEMF’s effects on circulation, inflammation, and tissue regeneration. However, species-specific responses, variable field dosimetry, and heterogeneity in methodologies highlight the need for additional controlled, parameter-standardized trials in performance horses [26]. Based on its positive effects on the musculoskeletal system, PEMF therapy is suspected of promoting relaxation before training or competition, making it a popular pre-conditioning tool for equine athletes. However, while anecdotal evidence and preliminary studies suggest benefits, ongoing research is essential to standardize PEMF protocols and better understand their mechanisms and long-term effects on equine health.

The current knowledge on PEMF therapy is scattered and sometimes inconsistent, with limited agreement on how it works and its effects. Additionally, despite increased interest in using PEMF on horses, few studies have examined its influence on equine physiology.

As an initial step in a series of necessary and rigorous investigations, the present study aims (1) to identify specific hematological and biochemical parameters that require detailed evaluation and monitoring in future research assessing the efficacy and physiological effects of PEMF therapy, and (2) to detect any significant changes that may indicate the development of adverse effects even after short-term PEMF exposure.

Given the scarcity of relevant data — most of which are either in vitro or conducted in species other than horses — we hypothesize the followings (1) hematological and biochemical parameters are expected to exhibit minimal changes, or only mild alterations potentially related to enhanced microcirculation, inflammatory modulation, or immunological activity, and (2) none of the measured parameters will exhibit adverse effects following PEMF treatment; thus, all values are expected to remain within clinically physiological ranges.

A specific set of primary endpoints was established to manage multiplicity and enhance the interpretability of results. These include hematological and biochemical parameters most likely to indicate short-term physiological responses to PEMF therapy, especially those related to microcirculatory activation and erythropoiesis (hematocrit, hemoglobin, red blood cell indices, and selected electrolytes). All other measured parameters are considered secondary or exploratory outcomes, aimed at providing broader contextual information and aiding in the identification of potential targets for future hypothesis-driven studies.

We believe these findings will help address a critical gap in the current understanding of PEMF therapy in horses and contribute to a more evidence-based approach. This knowledge may support veterinarians and equine practitioners in applying PEMF more safely and effectively, while minimizing the potential for misuse.

MATERIALS AND METHODS

Animals

The experiment was conducted on five warmblood horses at Fabiancsics Horses Stables (Budapest, Hungary). All the animals were healthy adults, competing sport horses ranging from 6 to 15 years old. Three of them were mares and two geldings, which had not been used for research previously. They were free of any medical treatment during the experimental period and had not received systemic medications. The animals involved in the experiment were kept individually in the same stable under normal conditions, with straw bedding in single boxes (4 × 4 m), and no changes were made to their daily routine. Horses had all been stabled at the same location and trained by the same person in moderate to intense work six days a week (including jumping and dressage lessons) for at least one year. Horses had ad libitum access to a water supply and, according to their routine, received three meals daily, at approximately 7:00 a.m., 12:00 p.m., and 5:00 p.m. Their feed consisted of their routine feed, which included a basic meal of oats without any other supplements or medications at the allocated time slots. The horses also received hay twice a day, and part of the usual daily routine was being outdoors in a 20 m ×40 m paddock for approximately 2 hr. Although individual feed and water intake, fecal output, and spontaneous activity were not quantitatively recorded as formal study endpoints, no relevant abnormalities in physiological status or general condition were noted during the observation period.

A five-level body condition score was applied to evaluate the horses’ body condition. On a scale of 1–5, 1 represents extreme underweight, and 5 represents extreme overweight. The ideal body condition score is in the middle of the scoring line at number 3. Each horse was scored to have an average between 3 and 3.6, indicating excellent body condition.

The experimental procedures were conducted under permit No. PE/EA/01032-6/2024 granted by the Animal Protection Authority of the Hungarian Government Office (vested with the authority to issue ethical approvals based on the Hungarian Government Decree No. 40/2013. in line with the European Union Directive 2010/63/EU).

Apparatus/Device

This study utilized an “Equi Terra” PEMF blanket manufactured for warmblood horses (model EMC-230928/1; provided by VLP Trade Kft, Győr, Hungary). The device comprises a full-body blanket with 14 strategically placed coiled copper wires that generate targeted electromagnetic pulses at key points on the horse’s body. It is completed with four limbs (4 × 2 coils), a chest (2 coils), and a head (2 coils) attachment. The blanket is controlled by a central touchscreen device connected to an external battery pack (Fig. 1).

Fig. 1.

The Pulsed electromagnetic field (PEMF) device and its placement on horses. A: Full setup with all its attachments. B: PEMF blanket with the control panel on a horse. C: Hind limb PEMF boot on a horse.

The manufacturer validated the frequencies and intensities of the blankets before use in the study. The device operates within a frequency range of 1 Hz to 20 KHz (pre-programmed settings 1–400 Hz), producing an adjustable magnetic field intensity of 1–190 μT (5 W). The blanket can run 29 different programs with pre-set frequencies. However, basic parameters (frequency range and intensity) can also be set manually. Based on the manufacturer’s recommendations, two distinct settings were employed in the present experiments. First, a ‘Pre-work program’ was applied for 20 min, exerting an increasing frequency of 1–70 Hz. This program is routinely used before exercises to increase muscular blood flow and aid warm-up. Following this, a customized 15-min session at a stable 8 Hz was used to stimulate hypothalamic activity through specific neural firing patterns [50, 60, 75].

Experimental setup

Five horses were included throughout the experiment to minimize animal use, with the same animals serving both as controls and for the PEMF therapy. Each horse received daily PEMF therapy for five consecutive days. Following each treatment, the horses underwent regular training sessions to maintain their typical exercise regimen and ensure consistent physiological conditions.

Blood samples were collected from the jugular vein one day before the start of PEMF treatment (to serve as the control baseline) and after the final treatment session. To account for potential variations in biological activity throughout the day, four samples were consistently collected between 6:00 and 7:00 a.m. (before their first daily meal and their daily physical activity) both on the day before the experiment (prior to the first PEMF treatment) and on the final day (one day after the last PEMF session). Based on these time points, the results were grouped into two clusters (‘before’ and ‘after’ groups), referred to as pre-treatment and post-treatment data.

Blood samples were analyzed at the validated diagnostic laboratory of the Department of Clinical Pathology and Oncology, University of Veterinary Medicine, Budapest. The measurement of hematological parameters was performed using Advia 2120i Hematology System (Siemens Healthineers, Forchheim, Germany). Biochemical analyses of blood serum were executed using AU480 Chemistry Analyser (Beckman Coulter Diagnostics, Krefeld, Germany), serum amyloid A (SAA) concentrations were determined using an immunoturbidimetric assay (Eurolyser, Austria; catalogue no. HBR0070). Total thyroxine and cortisol concentrations were measured using CLIA with the Immulite 2000 XPi (Siemens Healthineers). The examined blood parameters are summarized in Table 1.

Table 1. List of physiological blood parameters examined in the study.

Hematological parameters
RBC (red blood cell count)	PCT (plateletcrit)	Monocyte count
Hemoglobin	PDW (platelet distribution width)	Large unstained cells %
Hematocrit	White blood cell count	Large unstained cells count
MCV (mean corpuscular volume)	Neutrophil granulocyte %	Reticulocyte %
MCH (mean corpuscular hemoglobin)	Neutrophil granulocyte count	Reticulocyte count
MCHC (mean corpuscular hemoglobin concentration)	Eosinophil granulocyte %	MCVr (mean corpuscular volume for reticulocytes)
CHCM (cellular hemoglobin concentration mean)	Eosinophil granulocyte count	CHCMr (cellular hemoglobin concentration mean for reticulocytes)
CH (hemoglobin content)	Basophil granulocyte %	CHr (hemoglobin content for reticulocytes)
RDW (red cell distribution width)	Basophil granulocyte count	L-RTC% (Low Reticulocyte Percentage)
HDW (hemoglobin distribution width)	Lymphocyte %	M-RTC% (Medium Reticulocyte Percentage)
Thrombocyte count	Lymphocyte count	H-RTC% (High Reticulocyte Percentage)
MPV (mean platelet volume)	Monocyte %
Blood biochemistry parameters
Albumin	Fructose amine	K+ (potassium)
Globulin	Glucose	Na+/K+ ratio
Albumin/globulin ratio	Total bile acids	Fe3+ (iron)
Total protein	Lipase	Cl- (chloride)
AST (aspartate aminotransferase)	Triglyceride	Mg2+ (magnesium)
ALT (alanine transaminase)	Total cholesterol	Free iron-binding capacity
ALKP (alkaline phosphatase)	Creatinine	Total iron-binding capacity
GGT (gamma-glutamyl transferase)	CK (creatine kinase)	Uric acid
GLDH (glutamate dehydrogenase)	Inorganic phosphate	Carbamide
Total bilirubin	Total calcium	LDH (lactate dehydrogenase)
Direct bilirubin	Ca+ (calcium)	SAA (serum amyloid A)
Alpha-amylase	Na+ (sodium)
Endocrinological parameters
Cortisol	Thyroxine (T4)

This exploratory study was designed as a within-subjects repeated-measures experiment, in which each horse served as its own control. Pre- and post-treatment samples were taken at consistent times of day over a short period to minimize inter-individual variability and the effects of short-term physiological fluctuations. Additionally, all horses were kept under standardized management conditions throughout the experiment, including stable housing, feeding schedules, and training routines, to limit non-treatment-related variability in the measured parameters. The horses used in this study were accustomed to routine handling and venipuncture as part of their regular management, as well as to heavy blankets, which keepers use to cover animals daily. The study was carried out in early spring, prior to the onset of the competition season, during which training intensity, feeding regimens, and overall management conditions remained stable, with no significant changes in feed composition occurring.

Data analysis

The results were grouped into pre- and post-treatment data, which were analyzed using the non-parametric Wilcoxon matched-pairs signed-rank test. Statistical significance was considered if q-values were below 0.05. The tests were performed using GraphPad Prism version 9 (GraphPad Software, San Diego, CA, USA) and with the assistance of the Department of Biostatistics at the University of Veterinary Medicine Budapest, Hungary.

It is important to note that some parameters showed statistically significant changes, but they were numerically small, and they did not exceed the analytical coefficients of variation (CVs), indicating that they likely reflect measurement variability rather than true biological effects.

RESULTS

The pre-and post-treatment results of each examined parameter were calculated and compared. The data are presented in Tables 2–4 (as well as in a supplementary table), along with a visualization of the results in comparison to normal physiological ranges that may differ from those commonly reported in the literature. The ranges applied here have been validated by the equine clinic at the University of Veterinary Medicine, Budapest, ensuring a precise framework for evaluation. The numeric values of the reference intervals are indicated in Tables 2–4, ensuring the clarity of the evaluation framework.

Table 2. Hematological blood parameters pre-treatment and post-treatment.

Table 3. Biochemistry blood parameters pre-treatment and post-treatment.

Table 4. Endocrinological blood parameters pre-treatment and post-treatment.

	Unit of measurement	Pre-treatment			Post-treatment			q-value
		Mean	SD	CV%	Mean	SD	CV%
T4	nmol/L	26.8	± 6	22.39	28.8	± 8.86	30.76	0.1512
Cortisol	nmol/L	69.9	± 26.31	37.64	58.6	± 20.3	34.65	0.0538

The last column visualizes the location of the parameter relative to the physiological range: upper (grey) triangles=pre-treatment results; lower (black) triangles=post-treatment results. Light grey lines with bold letters show significant differences between pre- and post-treatment data (q<0.05). CV%=coefficients of variation.

Most hematological parameters remained unaffected after PEMF treatment and stayed within the physiological range (Table 2). Three parameters fell outside the physiological range both before and after the PEMF therapy. From these parameters, the platelet distribution width and reticulocyte count decreased post-treatment, remaining above the upper limit, and the hemoglobin content showed the same result at both measurement points.

Among the examined parameters, we found a significant decrease in reticulocyte count, percentage, and mean platelet volume. The statistical analyses also revealed significant differences in several other parameters (MCV, MCH, CHCM, plateletcrit, large unstained cells %, and cellular hemoglobin concentration mean for reticulocytes), although these differences are small.

The blood biochemistry parameters showed more variance before and after PEMF treatment (Table 3). Many of those parameters fell outside the physiological range. These were either (1) unaffected by the therapy, (2) PEMF brought them closer to the physiological range (remained outside of the normal range), or (3) only post-therapy results fell outside of the range. The first category (unaffected) includes lipase, LDH, glucose, and total cholesterol. The second category (improved) includes creatinine kinase (CK) and aspartate aminotransferase (AST). The third category, where PEMF moved the parameter outside the range, includes globulin and direct bilirubin.

The statistical analyses revealed significant differences in many parameters (within and outside the physiological range). Most of these significant changes were in a negative direction, and a post-treatment decrease was detected in albumin, carbamide, chloride, creatine kinase, creatinine, free iron-binding capacity, globulin, glutamate dehydrogenase, aspartate aminotransferase, alanine transaminase, sodium, total bilirubin, total iron-binding capacity, total protein, and uric acid. On the other hand, a significant increase was realized in albumin/globulin ratio, direct bilirubin, fructose amine, and total calcium.

Finally, we assessed the horses’ thyroid function and stress levels (Table 4). No significant differences were observed in the examined hormone levels (cortisol and thyroxine) before and after treatment.

DISCUSSION

While PEMF therapy is widely recommended for revitalization and pathological conditions in the horse industry, its potential impact on healthy individuals remains an important area of exploration. This study investigated whether the applied whole-body PEMF therapy induced deviations in the examined parameters. Our objective was to determine whether a routinely applied series of whole-body treatments influences the general physiology and health of the animals. Our analysis here focuses exclusively on interpreting the key phenomena highlighted in the results section. Due to the limited literature on PEMF therapy in horses, we compare our observations with relevant in vivo results (from rodent or equine studies, if available); otherwise, we reference in vitro findings.

A general overview of all findings reveals that 5 days of PEMF therapy resulted in no changes or a decrease in most parameters, except for direct bilirubin, fructose amine, and calcium. This suggests that short-term treatment on consecutive days has no harmful effects on the general physiology and health of the animals. As we delve into the details, we can observe that many out-of-range parameters were found closer to the physiological range post-treatment (PDW, reticulocyte count, AST, CK, etc.), which may indicate some positive effects on animal health. This idea can be further strengthened if we consider that those parameters that moved outside of the range after the treatment can also be regarded as a positive effect, such as a decrease in CK, which could indicate reduced micro-injuries of skeletal muscle, and lower globulins (which encompass acute-phase proteins) might be a sign of decreasing inflammations [17, 82]. In line with this, the observed slight decrease in albumin (classified as a negative acute-phase protein) may reflect the early onset of a negative acute-phase response [51]. This anti-inflammatory effect is further supported by other studies demonstrating PEMF’s capacity to lower pro-inflammatory cytokine expression and mitigate organ damage in models of systemic inflammation [46, 47, 52, 55].

In our experiment, the absence of changes in cortisol and thyroxine levels following PEMF therapy may be attributed to several factors. However, it likely indicates that the treatment does not directly affect horses’ stress or thyroid pathways. Some studies suggest that PEMF may have a calming or stress-reducing effect [33], which could theoretically lead to lower glucocorticoid concentrations. However, recent studies in horses have failed to demonstrate significant changes in cortisol levels [31]. Likewise, while some research suggests that PEMF might directly influence thyroid function by affecting the thyroid gland’s ability to produce hormones or indirectly through cellular regeneration and reduced inflammation [22, 85], we could not detect any changes in this regard. In summary, our findings indicate that PEMF therapy did not evoke a stress response detectable through cortisol levels or affect thyroid function despite significant positive effects on other metabolism-related blood parameters.

Findings from the existing literature indicate that PEMF therapy has the potential to modulate specific hematological parameters, particularly influencing bone marrow cell proliferation and differentiation in a dose-dependent manner [24, 55, 66]. However, most of these data originate from either in vitro studies or rodent models, necessitating caution when extrapolating the results to equine subjects. In rodent models, PEMF has been shown to increase white blood cell and lymphocyte counts, while other parameters, such as red blood cells, hemoglobin, and platelets, remained unaffected [40]. In our present study, most hematological parameters, including those related to white blood cells, did not show significant changes following PEMF treatment and remained within the physiological range.

One of the most promising effects of PEMF therapy is its impact on hematological parameters, as improvements in blood flow and changes in red blood cell behavior have been well-documented. Studies indicate that PEMF may enhance red blood cell membrane flexibility, decrease aggregation (clumping), and support better oxygen transport efficiency [15, 57, 58, 71]. These effects enable red blood cells to move more easily through capillaries, thereby boosting tissue oxygenation. Additionally, PEMF’s influence on blood rheology and erythrocyte membrane stability can favorably affect hematocrit and hemoglobin levels, depending on the intensity of the electromagnetic field [4, 30, 59, 77, 80]. Unexpectedly, our experiment did not reveal significant changes in hematocrit or hemoglobin levels; however, reticulocyte percentage and count showed a marked decrease following short-term PEMF treatment. Reticulocyte indices, determined using a species-validated analyzer, confirmed reliable detection despite the typically low levels in healthy horses (<0.1% of erythrocytes; [6, 16]). The stable CHr values argue against iron-restricted erythropoiesis, as hemoglobin content of reticulocytes is among the earliest indicators of iron limitation. Likewise, the modest reduction in TIBC with unchanged serum iron might reflect reduced transferrin demand or improved iron utilization [53].

Closely related to its effects on microcirculation and blood supply, PEMF therapy may positively influence iron metabolism by enhancing blood flow, cellular metabolism, and reducing inflammation [84]. Better microcirculation facilitates iron uptake and transport, while PEMF-enhanced mitochondrial bioenergetics supports the energy needs of iron-dependent cells [63, 79]. Although direct evidence still requires more research [36], our current findings support this idea, as we observed reductions in both free and total iron-binding capacity. Additionally, PEMF’s anti-inflammatory effects and its ability to stabilize hepcidin (a key regulator of iron absorption) may further improve iron availability and utilization [36, 73].

Together, these findings could potentially be linked to a shift toward more mature erythropoiesis rather than a restrictive or deficient state. One possible explanation is that PEMF enhances microcirculation and blood rheology, improving oxygen and nutrient delivery to the marrow and supporting erythropoiesis, as suggested by previous studies on blood flow and red cell membrane integrity under oxidative stress [3, 65, 68]. Rather than indicating suppressed bone marrow activity, the reduced reticulocyte count may reflect enhanced RBC maturation and improved marrow efficiency, likely facilitated by PEMF-induced improvements in microcirculation, oxygen delivery, and red cell membrane dynamics [11, 49]. This interpretation aligns with the unchanged L-RTC%, M-RTC%, and H-RTC% distribution observed, suggesting balanced erythropoiesis and improved hematologic equilibrium [41].

PEMF therapy has been explored for its effects on muscle-related biochemical parameters, particularly creatine kinase and lactate dehydrogenase, which are markers of muscle damage and tissue injury [42, 55, 70]. Human studies have shown significant increases in blood lactate concentration during short-term PEMF exposure, likely due to its impact on glycolytic metabolism [72]. In contrast, in our experiment, LDH levels remained unaffected by PEMF treatment. On the other hand, although significant increases in CK activity have been observed in rodent studies [39], no such robust changes were detected in our study. These suggest that either longer or intensive PEMF treatment is required, or the underlying mechanisms are more complex, and the positive effects remain veiled.

PEMF therapy has been associated with various physiological effects that may influence liver function parameters. The observed stability of aspartate aminotransferase (AST) levels suggests that PEMF does not adversely affect hepatocellular integrity. The observed decrease in albumin levels, while remaining within normal ranges, might reflect a transient modulation in protein synthesis or distribution, potentially due to improved microcirculation and tissue perfusion [45]. The increase in direct bilirubin, despite total bilirubin remaining within normal limits, could suggest a transient modulation of bile flow or hepatocellular function or the clearance of bilirubin [2, 21, 69]. Potential alternative explanations such as sample or training-related hemolysis, cholestasis, starvation effects, or assay variation were considered unlikely in this context: hemolysis indices were checked and found to be within acceptable limits, horses were maintained under controlled feeding and training conditions, and no clinical signs indicative of cholestasis or other hepatic dysfunction were observed.

PEMF therapy has also been investigated for its potential effects on carbohydrate and lipid metabolism, and several studies have reported notable outcomes [48, 63, 67]. In our study, glucose levels remained unchanged following PEMF treatment. In both human and rodent studies, lipid metabolism and transport have been reported to be affected by exposure to electromagnetic fields [7, 20, 35, 76, 83]. In our experiment, however, none of the lipid-related parameters, such as total cholesterol, lipase, and triglycerides, exhibited significant changes, and their values remained unaffected in relation to the physiological range.

In this study, we aimed to evaluate parameters that reflect the general health status of the animals, with a particular focus on their physiological ranges and potential alterations following PEMF treatment. In addition to assessing whether PEMF influenced these parameters, we observed several significant changes in values that have not been reported in the literature. Although these findings were not the primary objective of our study, and the experimental design was not specifically tailored to investigate them, they warrant consideration for future research. Understanding these changes could provide valuable insights into the physiological mechanisms influenced by PEMF, particularly in relation to the physical activity and performance of the horses.

Limitations

This study has limitations to consider when interpreting the results. First, the sample size and experimental design were primarily influenced by animal welfare concerns and the need to keep all animals in standardized, consistent conditions. Additionally, when establishing the baseline and monitoring changes in blood parameters, factors such as the owner’s desire to limit blood draws and prioritize animal welfare played an important role. These are fundamental challenges inherent to field-based veterinary research. Assessing real-world effects forces the study design to navigate a delicate trade-off between procedural habituation, environmental confounding, and baseline stability. To tackle these challenges, we used a single treatment-free baseline period, and blood samples were collected at multiple matched time points before and after treatment, while rigorously maintaining standardized management conditions. We ensured that the animals performed work of similar difficulty and intensity before and during the experiment, under the supervision of a qualified professional.

It is important to acknowledge that our study design cannot fully rule out the possibility that some of the observed variation may be due to spontaneous, uncontrollable fluctuations rather than solely to PEMF exposure. Future studies incorporating a repeated treatment-free baseline, a crossover design, and/or a sham-exposed control condition would enable more robust quantification and strengthen the causal interpretation of the observed changes. However, implementing a repeated baseline requires careful consideration. Closely spaced baseline periods may lead to habituation effects associated with handling, blood sampling, or exposure to the device, while longer intervals could exacerbate the influence of environmental factors and management-related variability.

Despite these limitations, it is important to recognize that our early and somewhat unexpected findings (i.e., several blood parameters showed changes in a short period, all within normal physiological ranges) indicate a broader impact of the intervention beyond initial expectations.

Conclusions

In conclusion, the whole-body application of the PEMF device under the specified experimental conditions did not elicit any detectable adverse effects on the animals’ health and stress response. While most parameters remained unchanged, several biochemical and hematological values showed significant alterations. Notably, the parameters that exhibited positive changes were primarily associated with muscle function, blood circulation, and general metabolism. These findings suggest that whole-body exposure to beneficial electromagnetic fields may support the physical state of otherwise healthy animals, indicating a potential role for PEMF therapy in animal training or exercise preparation. On the other hand, PEMF appears to have significant effects on hematology, which also suggests that horse clinicians and trainers should exercise caution when using this method.

PEMF therapy is still under-researched in horses, with no existing data on its effects on the whole body and blood parameters. This study was intended as an initial step toward filling these knowledge gaps, with a primary goal of raising awareness and encouraging further research into the potential mechanisms of PEMF therapy. We hope this article provides food for thought for researchers interested in investigating these effects more thoroughly. Despite the above-mentioned limitations, the insights gained can serve as a valuable stepping stone for future, more controlled research in this promising field.

CONFLICTS OF INTEREST

The authors declare no relevant financial or non-financial interests. The founding sponsor had no role in the design of the study; in the collection, analysis, or interpretation of data; or in the writing of the manuscript.