New Way to Assess Fitness in Horses?

Hello, Summarians!

As the year draws to a close, I would like to thank you for supporting my passion project.

I hope that it has informed you and led to discussions with friends and colleagues about the new insights you have gained.

If it is valuable to you please consider sending it on to a friend 😄 

Heart rate variability in horses

Several methods have been developed to assess equine fitness, including standardized exercise tests (SET) to estimate physiological variables like VLA4 and V200. However, standardized workloads are challenging under field conditions. Heart rate variability (HRV), which reflects fluctuations in the interval between heartbeats, offers a noninvasive alternative to assess autonomic nervous system (ANS) function. HRV analysis involves both linear (time and frequency domain indexes) and nonlinear methods, with frequency domain variables like LF (low frequency) and HF (high frequency) providing insights into sympathovagal balance. 

This study examined the ANS response to six weeks of training in horses using linear HRV analysis and compared it to aerobic fitness improvements measured through V̇O2max. Results showed that training increased V̇O2max and LF/HF ratios without significant changes in resting heart rate or echocardiographic variables. HRV changes, particularly in the LF domain, were correlated with V̇O2max improvements, suggesting LF is more sensitive than HF to training. LF appears to reflect both sympathetic and parasympathetic inputs, while HF primarily represents parasympathetic activity. 

HRV proved more sensitive than resting heart rate as a fitness indicator, highlighting its potential for monitoring training progress. However, variability in HRV methodologies, including differences in frequency bands, recording conditions, and software, complicates comparisons across studies. Despite consistent recording conditions in this study, further research is needed to standardize HRV analysis in equine studies and explore nonlinear HRV variables. 

The lack of significant echocardiographic changes may reflect the horses’ prior training history or the short training duration. While previous studies have shown long-term training effects on cardiac dimensions, this study’s 6-week period may have been insufficient to induce measurable changes. Advanced echocardiographic techniques might detect subtler responses to training. The study also highlights the influence of factors like age, growth, stress, and fatigue on HRV and the importance of controlling these variables in future research. 

In conclusion, HRV, particularly the LF domain, may serve as a sensitive tool for monitoring equine fitness during training. Standardized methods and additional research are needed to enhance its application and reliability in veterinary science. 

Santosuosso E, Léguillette R, Shoemaker S, et al. A consort-guided randomized, blinded, controlled clinical trial on the effects of 6 weeks training on heart rate variability in thoroughbred horses. J Vet Intern Med. 2025; 39(1):e17253. doi:10.1111/jvim.17253 

Bottom line — Might be a better way of assessing.

Compounded Keppra

Levetiracetam (LEV), an anti-epileptic drug, primarily binds to the synaptic vesicle protein SV2A, influencing neurotransmitter release in the central nervous system. Its mechanism of action is multimodal and includes effects on cellular transporters, neuronal excitability, and GABAA receptor stabilization. LEV is widely used for treating epilepsy in humans, gaining FDA approval in 1999, and is used extra-label in veterinary medicine for dogs and cats due to its efficacy, safety, mild adverse effects, and suitability for patients with hepatic dysfunction. 

Commercially, LEV is available in immediate-release (LEV-IR) and extended-release (LEV-ER) formulations. Pharmacokinetic studies in dogs have shown that LEV-IR has a high oral bioavailability, a short half-life of 2–3 hours, and requires dosing every 8 hours. LEV-ER, on the other hand, has a prolonged half-life of 4–5 hours, enabling twice-daily dosing. LEV-ER tablets must be administered intact to maintain extended-release properties, which poses challenges for smaller or noncompliant patients due to the tablet size and dosing limitations. 

A compounded LEV-ER formulation (PO-COMP) offers potential advantages, including the ability to partition the tablet without compromising extended-release properties. A study was conducted to assess the pharmacokinetic parameters and bioequivalence of PO-COMP compared to a commercially available LEV-ER formulation (PO-COMM) in healthy dogs. Results showed that while PO-COMP had slightly lower absolute bioavailability compared to PO-COMM, it was bioequivalent using the 90% confidence interval method. Despite individual variability, both formulations maintained therapeutic serum concentrations for at least 12 hours. 

The study highlighted potential variability in drug absorption and terminal half-life among individual dogs, suggesting a need for further research to confirm the clinical relevance of these findings. The compounded formulation's use of Methocel K100M and silicified microcrystalline cellulose appeared to preserve extended-release properties even when the tablets were partitioned. While the study demonstrated bioequivalence, the compounded formulation's efficacy and safety should be evaluated in multi-dose studies and larger sample populations. 

In conclusion, PO-COMP is a promising alternative for dogs that cannot tolerate or adhere to the dosing requirements of LEV-IR or commercial LEV-ER. Its potential to improve medication adherence and seizure control underscores the need for further efficacy and therapeutic drug monitoring studies to optimize its use in veterinary medicine. 

Paushter, A.M., Foss, K.D., Reinhart, J.M., Forsythe, L.E. and Hague, D.W. (2024), The Single-Dose Pharmacokinetics of a Compounded Levetiracetam Formulation and Bioequivalence to a Commercial Formulation in Healthy Dogs. J Vet Pharmacol Therap. https://doi.org/10.1111/jvp.13490  

Bottom line — This could be a very helpful development.

Pet Parenting

Pet parenting is an emerging phenomenon that reflects a shift in how humans perceive companion animals, particularly dogs, integrating caregiving strategies commonly associated with the parent-child relationship. This systematic review analyzed 15 studies to provide an overview of patterns and themes within dog-directed parenting. 

The research identified three primary thematic areas. The first focused on the use of parent-child terminology in describing relationships with companion animals. The studies found that terms such as "father" or "parent" are widely used, influenced by factors like cultural norms, the conversational context, and whether individuals have children. The second theme explored the influence of offspring, culture, and gender on pet parenting. Studies revealed that having children often reduces the intensity of attachment and resource investment in dogs. Cultural differences and gender also shape how pet parenting is practiced, with disparities noted in various societies. The third theme examined dog-directed parenting styles, drawing parallels to traditional human parenting styles (authoritative, authoritarian, and permissive). These styles are defined by guardians’ levels of demand and responsiveness and significantly impact dogs’ behavior, sociability, attachment, and problem-solving abilities. 

The review highlighted the relevance of authoritative parenting strategies, emphasizing their positive impact on dogs' health and well-being. It also noted that urbanization, declining fertility rates, and changing life orientations contribute to the growing phenomenon of pet parenting, particularly among nonparents. These individuals often invest emotional and financial resources in their companion animals as a nurturing alternative to raising children. 

Despite its insights, the review noted limitations, such as a predominance of female participants in the studies and a lack of exploration into the experiences of male pet parents. The authors called for further research to address these gaps and deepen understanding of dog-directed parenting practices and their implications for dog welfare and human-animal relationships. 

Mita Barina-Silvestri, Marcos Díaz-Videla, Rafael Delgado-Rodríguez, Pet parenting: A systematic review of its characteristics and effects on companion dogs, Journal of Veterinary Behavior, Volume 76,  2024, Pages 13-24, ISSN 1558-7878, https://doi.org/10.1016/j.jveb.2024.09.003. 

Bottom line — Interesting insights.

Just putting things in perspective …