Arythmias And Exercise In Horses.

Hello, Summarians!

How does exercise and fitness relate to the potential for heart related issues? How might that show up during the activity istself? Big questions and not a lot of controlled studies to help us make approprtiate decisons. Here is one that might help as well as a couple of push the limits in terma of believability …

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ADHD And Sleep In Dogs

This study explored how ADHD-like traits in pet dogs relate to cognitive flexibility, using a spatial reversal-learning task administered twice—once before and once after a monitored sleep session. Dogs with higher ADHD scores, based on validated owner questionnaires measuring inattention, hyperactivity, and impulsivity, required more trials to reach the learning criterion in the first test. This mirrors well-established findings in humans, where ADHD is associated with poorer performance on set-shifting and cognitive flexibility tasks. By contrast, performance differences disappeared in the second test. The authors propose that repeated exposure to the task—combined with sufficient sleep—particularly benefited dogs with higher ADHD scores. Dogs who slept more effectively between the tests showed greater performance improvement, suggesting that sleep may support gains in cognitive flexibility, similar to its known role in memory consolidation across species. 

The study also revealed age-related declines in reversal learning but only in the second test. This may reflect the inclusion of dogs with high ADHD scores whose impairments initially masked age effects. The sleep EEG component of the study highlighted practical challenges: dogs with more pronounced ADHD-like traits were harder to prepare for EEG recordings and were more likely to yield unusable data, unlike younger dogs whose initial difficulties could be resolved with patience. These findings indicate that dogs high in ADHD-like traits may require additional familiarisation or improved EEG methods to ensure reliable sleep data, otherwise studies risk unintentionally excluding them and biasing results. 

Although the study could not employ distinct clinical vs non-clinical ADHD groups—because canine ADHD diagnostic criteria were not yet established—it supports a dimensional view of ADHD-related traits, consistent with modern human neurodevelopmental research. Some limitations include variation in the time needed for electrode placement and the absence of a non-sleep control group, leaving open whether sleep specifically enhanced performance or whether quiet rest alone would suffice. 

Overall, the findings show that dogs’ cognitive flexibility is meaningfully associated with ADHD-like traits and influenced by sleep. Repeated task exposure and adequate sleep may help mitigate flexibility impairments in dogs with higher ADHD scores. The study also underscores methodological challenges in using non-invasive sleep EEG in such dogs and highlights the importance of improving EEG techniques to better capture the neural basis of ADHD-related behaviours. 

Kovács T, Reicher V, Csibra B, Csepregi M, Kristóf K, Gácsi M. Repeated Task Exposure and Sufficient Sleep May Mitigate ADHD-Related Cognitive Flexibility Impairments in Family Dogs. Animals. 2025; 15(21):3074. https://doi.org/10.3390/ani15213074 

Bottom line — There is a relationship. Power naps for dogs ???

Arythmias And HRV With Exrecise In Horses

This study examined how common exercising arrhythmias and heart rate variability—specifically DFA-α1—behave in eventing horses during cross-country competition, and whether these measures relate to performance or exercise intensity. Arrhythmias were extremely frequent, occurring in 74% of recordings and 81% of horses, which aligns with previous research showing that fit equine and human athletes often develop transient rhythm disturbances during intense exertion. The higher heart rates and the demanding nature of a competition environment likely contributed to the elevated arrhythmia frequency compared with controlled training tests. Because horses were included based on reported good health rather than full cardiac workups, some may have had unrecognized heart disease, although most arrhythmias observed were consistent with physiological responses to heavy exercise. 

DFA-α1 values averaged 0.64, which in humans would fall between the “heavy” and “severe” exercise intensity domains. Horses in this study had high post-exercise blood lactate concentrations, confirming that the cross-country effort was intense. The study highlights that DFA-α1 may behave differently in horses than in humans, and that the irregular, variable demands of cross-country—jumps, terrain changes, accelerations—could complicate interpretation. Artefact correction for arrhythmias also reduces precision of HRV-based metrics. Although HRV shows promise for automated arrhythmia or subclinical disease detection, its usefulness as a real-time marker of equine exercise intensity remains uncertain in this context. 

Unexpectedly, horses with more premature depolarizations and more arrhythmias—especially during recovery—tended to accumulate fewer time penalties on cross-country. This suggests that arrhythmias, at least in their mild forms, may reflect higher exercise intensity rather than impaired performance. Conditioning and cardiovascular adaptations in highly trained horses may themselves promote benign rhythm disturbances, an idea paralleling the “athlete’s heart” described in human sports medicine. However, arrhythmias during cross-country were also associated with more showjumping penalties the following day, perhaps because horses that worked harder in cross-country accumulated more fatigue. Similarly, higher DFA-α1 during cross-country—a value thought to represent lower physiological strain—was linked with better showjumping outcomes. These relationships were modest and influenced by factors such as age, sex, and Thoroughbred percentage, all of which modified how arrhythmias related to performance. 

Markers of exercise intensity such as heart rate, speed, distance, and blood lactate were strongly associated with the number of premature beats but were not clearly linked to DFA-α1. This contrasts with controlled laboratory exercise studies, where DFA-α1 corresponds more reliably to lactate thresholds. The chaotic nature of cross-country exertion likely disrupts these associations. Horses capable of high blood lactate production and higher heart rates tended to perform better in the cross-country phase, reflecting the advantage of strong glycolytic capacity during high-intensity efforts. Interpreting lactate levels after maximal efforts is different from interpreting them after standardized submaximal tests, where lower lactate typically indicates superior fitness. 

In conclusion, arrhythmias were very common during eventing cross-country and not necessarily detrimental to performance. DFA-α1 did not function as a reliable marker of exercise intensity in this setting, though higher values were associated with better showjumping performance. Arrhythmias appeared to correlate more with the intensity of effort than with impaired athletic ability. The study underscores that important questions remain about which arrhythmia patterns truly affect performance or safety and emphasizes that sex, age, and breed composition can influence arrhythmia–performance relationships. 

Navas de Solis C, Ramseyer A, Stefanovski D, Haughan J, Solomon CJ, Kirsch K. Association of heart rate variability, exercise intensity and exercising arrhythmias with competition results in eventing horses. Equine Vet J. 2025; 57(6): 1446–1456. https://doi.org/10.1111/evj.14491 

Bottom line — Seems to beintesity of effort not impaired performance

Microbots For Drug Delivery

Magnetic microrobots have emerged as a promising alternative to systemic drug delivery, which is often limited by serious side effects and contributes to high drug failure rates in clinical trials. Over the past two decades, advances in materials science, fabrication, and actuation have enabled sophisticated micro- and nanoscale machines capable of movement, drug loading, and in some cases real-time imaging. Although many components of this technology have progressed, clinical translation has been slow because most developments have occurred in isolation rather than as integrated systems ready for medical use. 

A major challenge is creating microrobot materials that are simultaneously biocompatible, biodegradable, and sufficiently magnetic for precise actuation—requirements that inherently limit achievable magnetization. Another obstacle is generating strong and controllable magnetic gradients across human-scale distances, as magnetic forces decay steeply with distance. Existing magnetic navigation systems are generally too small or impractical for clinical use. The recently developed Navion electromagnetic navigation system (eMNS) addresses this issue by enabling clinically relevant magnetic field control suitable for guiding superparamagnetic microrobots. 

Clinical application also depends on reliable real-time tracking and the ability to load and release meaningful quantities of therapeutic agents. The work described in this study presents an integrated microrobotic platform designed to meet these requirements. The system includes a clinical eMNS, a specialized release catheter, and a drug-carrying microrobotic capsule composed of FDA-approved, biocompatible materials. The capsule’s gelatin matrix incorporates zinc-doped iron oxide nanoparticles for magnetic actuation, tantalum nanoparticles for X-ray visibility, and therapeutic compounds for targeted treatment. Hyperthermia at the target site triggers microrobot dissolution and drug release, enabling local clot lysis or other therapeutic effects. 

The researchers demonstrated the system’s capabilities in vitro, ex vivo, and in vivo. They successfully navigated microrobots through large-animal vascular systems, visualized their movement with standard imaging modalities, and achieved effective drug release. In vitro thrombus-dissolution experiments showed the potential for targeted thrombolytic therapy, while navigation in porcine and ovine models proved feasible even in anatomically complex regions such as the central nervous system. 

These results mark a significant advance toward clinical translation by unifying navigation, imaging, therapeutic delivery, and biocompatible design into a single platform. The modular system could be adapted for applications ranging from ischemic stroke treatment to localized infection or tumor therapy. Future work will need to address long-term safety, scalability, and automation of navigation to reduce operator burden. Overall, the study provides a strong foundation for the eventual clinical deployment of microrobotic drug-delivery systems. 

Landers FC, Hertle L, Pustovalov V, Sivakumaran D, Oral CM, Brinkmann O, Meiners K, Theiler P, Gantenbein V, Veciana A, Mattmann M, Riss S, Gervasoni S, Chautems C, Ye H, Sevim S, Flouris AD, Puigmartí-Luis J, Mayor TS, Alves P, Lühmann T, Chen X, Ochsenbein N, Moehrlen U, Schubert T, Kulcsar Z, Gruber P, Weisskopf M, Boehler Q, Pané S, Nelson BJ. Clinically ready magnetic microrobots for targeted therapies. Science. 2025 Nov 13;390(6774):710-715. doi: 10.1126/science.adx1708.

Bottom line — Could be closer than we realize.

Just putting things in perspective …