DEXA Scans Estimate Healthspan?

Hello, Summarians!

We’ve heard that honey works wonders on wounds but what type is best? Here is a study that helps to answer that question.

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DEXA Scans and Aging in Dogs

Dual-energy x-ray absorptiometry (DEXA) is a validated, noninvasive method for estimating body composition in dogs and cats by emitting two x-rays of different energy levels to measure absorption by bone mineral and soft tissue. This study utilized DEXA scans performed between 2006 and 2023 to analyze changes in lean body mass (LBM), fat mass, total mass, bone mineral content (BMC), and bone mineral density (BMD) with age in a population of colony-housed dogs and cats fed a variety of commercially available foods. 

The primary hypothesis was that lean mass would increase to a peak and then decline (exhibiting a quadratic effect), fat mass would increase linearly, and BMC and BMD would remain unchanged with age. The results indicated that a decline in LBM may start as early as age 6 in dogs and age 4.5 in cats, which is earlier than previously documented and occurs before the mature adult life stage for many breeds. This early onset of lean mass loss is significant because LBM, mainly consisting of muscle and organ tissue, is essential for strength, immune function, and wound healing. Loss of LBM, known as sarcopenia, is associated with reduced health span and lifespan in both dogs and cats. 

Total body mass continued to increase until age 7 in dogs and age 5 in cats before stabilizing, suggesting significant growth beyond the traditionally defined adulthood at 12 months. Fat mass increased with age in both species. In dogs, percent body fat increased steadily, while in cats, fat mass increased until about age 7.7 before declining slightly until age 16. Excessive fat accumulation is linked to various health issues and reduced lifespan, highlighting the importance of monitoring and managing body fat. 

BMC and BMD peaked around age 7.1 and 5.1 in dogs and age 5 in cats before declining. The decline in bone mass and density with age raises concerns about increased risk of fractures and bone diseases. The study suggests that nutritional and behavioral strategies to mitigate lean mass loss should begin earlier than the mature adult life stage, potentially as soon as growth is complete. 

Several limitations were acknowledged, including the use of colony-housed animals predominantly of certain breeds (Beagles for dogs and domestic shorthairs for cats), which may limit breed diversity representation. The feeding strategies and diet histories were varied and not controlled, affecting the generalizability of the findings. Additionally, the number of DEXA scans per animal varied widely, and health status at the time of scans was not consistently recorded. 

The study emphasizes the need for further research to explore how body composition differs based on breed size, body condition, health status, and various nutritional strategies. Future work should also investigate these changes in client-owned pets living in home environments to enhance applicability. Despite its limitations, the study provides valuable baseline data on body composition changes with age in dogs and cats, underscoring the importance of early interventions to promote healthy aging and improve health span and lifespan in these companion animals 

McGrath, A. P., Hancock, L., Stiers, C. A., Brejda, J., & Morris, E. M. (2024). Retrospective analysis of dual-energy x-ray absorptiometry data demonstrates body composition changes with age in dogs and cats. American Journal of Veterinary Research https://doi.org/10.2460/ajvr.24.05.0132 

Bottom line — A new view on body composition changes during aging

Mechanism for Itching in Horses

Allergic skin diseases such as atopic dermatitis and insect-bite hypersensitivity (IBH) are prevalent in horses, causing significant itching (pruritus) that leads to self-trauma and secondary infections. Current treatments are limited, primarily involving glucocorticoids, immunotherapy, and fly control measures. Understanding the mediators of pruritus is crucial for developing better therapies. 

Interleukin-31 (IL-31) is a cytokine known to play a key role in inducing pruritus in humans, mice, and dogs by activating the IL-31 receptor α (IL-31RA) on sensory neurons, keratinocytes, and immune cells. This activation triggers downstream signaling pathways involving Janus kinase 1 and 2 (JAK1/2) and the signal transducer and activator of transcription proteins (STATs), particularly STAT3. 

This study aimed to characterize the role of IL-31 in equine pruritus. Researchers produced two recombinant proteins based on the confirmed mRNA sequence of equine IL-31. They demonstrated that intradermal injection of these recombinant IL-31 proteins in normal horses induced itching, confirming the cytokine's pruritogenic effect in vivo. The itching response was variable and delayed, mirroring observations in other species. 

In vitro experiments showed that stimulating equine adherent monocytes with recombinant IL-31 led to increased phosphorylation of STAT3, indicating activation of the downstream signaling pathway. RACE sequencing revealed discrepancies between their translated IL-31 protein sequence and existing sequences in genetic databases, suggesting potential variations in the equine IL-31 gene. 

The study faced limitations, including a small sample size and certain design flaws, such as not using an equivalent protein diluent as a control and a lack of blinding in observations. Despite these limitations, the findings support IL-31 as a mediator of pruritus in horses and highlight it as a potential target for new therapeutic approaches to treat allergic skin diseases in equines. 

Further research is needed to fully understand the mechanisms by which IL-31 contributes to pruritus in horses and to develop effective treatments targeting the IL-31 signaling pathways. 

Craig, N. M., Munguia, N. S., Trujillo, A. D., Chan, A. M., Wilkes, R., Dorr, M., & Marsella, R. (2024). Interleukin 31 mediates pruritus in horses. American Journal of Veterinary Research https://doi.org/10.2460/ajvr.24.05.0144 

Bottom line — Mediator knowledge is the key to treatment. Cytopoint for Horses ???

Medical Grad Honey vs Regular for Wound Treatment

Honey is widely used in both human and veterinary medicine for wound treatment due to its antibacterial properties, which stem from factors like high osmolarity, acidic pH, hydrogen peroxide activity, and phytochemicals. Manuka honey, rich in methylglyoxal (MGO), is particularly known for its antibacterial effects and is commonly used in medical-grade honey (MGH) products that undergo sterilization and meet strict antibacterial standards. This study compared the antibacterial activities of different types of honey—including MGH, non-medical-grade manuka honey, commercially sourced non-MGH, and locally sourced non-MGH—against common bacterial isolates found in dog and cat wounds: Staphylococcus pseudintermedius, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa. The findings indicated that MGH exhibited the lowest minimum bactericidal concentration (MBC) and the most consistent bacterial growth inhibition, making it more efficacious than other honeys tested. Non-medical-grade manuka honey had the second-lowest MIC90 and MBC values, while commercially and locally sourced non-MGH displayed variable efficacy but were sometimes comparable to manuka honey against certain bacteria. Although all honey types showed antibacterial activity at higher concentrations, locally sourced non-MGH generally had the lowest inhibitory effect. The study concludes that MGH should be preferred for wound management in cats and dogs due to its superior antibacterial properties, but acknowledges that cost and accessibility may make non-MGH honeys practical alternatives in certain cases. It emphasizes the importance of further research to substantiate the antibacterial efficacy of non-MGH honeys and to explore the properties of different MGH types, including those not based on manuka honey, for potential use in veterinary wound care. 

Neo, R., Gaonkar, P., Huber, L., & Hlusko, K. C. (2024). Medical-grade honey has superior antibacterial properties against common bacterial isolates in wound cultures of dogs and cats in comparison to non–medical-grade honey types. American Journal of Veterinary Research https://doi.org/10.2460/ajvr.24.07.0188 

Bottom line — Medical grade is best.

Just putting things in perspective …