Do Herpes Virus Vaccines Help?

Hello, Summarians!

Do vaccines work? Yes. Do some work better than others? Yes. How do we tell if they do? We look for independent, well-done studies and consensus reports. Here is one such attempt…

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What Internists Say About Herpes Virus in Horses.

Equine herpesvirus-1 (EHV-1) is a prevalent pathogen in horses, transmitted through oronasal secretions and contact with infected materials. Initial infection occurs in the upper respiratory tract, leading to symptoms like fever and nasal discharge, and then spreads to immune cells and various tissues. EHV-1 often results in lifelong latent infections, with periodic reactivations causing disease and virus shedding. 

In young horses, EHV-1 typically causes mild respiratory disease, but it can lead to severe outcomes like abortion in pregnant mares and equine herpesvirus myeloencephalopathy (EHM), a neurological disorder. EHM outbreaks significantly impact the equine industry. 

Control measures for EHV-1 include vaccination, infection control, and management practices. However, despite routine vaccination, outbreaks persist. This study systematically reviewed scientific literature to assess vaccine efficacy in controlling EHV-1 in horses. The review excluded gray literature and found incomplete reporting of methodological details in many studies, complicating bias assessment. 

The review identified diverse study designs and outcomes, reflecting in the meta-analyses. Modified-live vaccines (MLV) were effective in reducing pyrexia, viremia, and nasal shedding, despite severe heterogeneity in studies. Inactivated vaccines reduced pyrexia but had limited effects on viremia and nasal shedding. Other experimental vaccines were largely ineffective. 

Underpowered studies were common, particularly for outcomes like abortion and EHM, leading to inconclusive results. Meta-analyses failed to show that vaccination significantly prevented these outcomes due to study limitations. The review highlighted the need for rigorous, randomized, and blinded studies to better evaluate vaccine efficacy. 

The review adopted the OHAT GRADE framework for assessing animal studies, often resulting in low to very low confidence ratings due to risk of bias and imprecision. A notable publication post-review confirmed similar findings regarding vaccine efficacy and study quality. 

Overall, the meta-analysis underscored the need for higher-quality studies to inform EHV-1 vaccination strategies, emphasizing the necessity for well-designed trials to evaluate vaccine effectiveness in preventing key clinical outcomes in horses. 

Osterrieder K, Dorman DC, Burgess BA, et al. Vaccination for the prevention of equine herpesvirus-1 disease in domesticated horses: A systematic review and meta-analysis. J Vet Intern Med. 2024; 38(3): 1858-1871. doi:10.1111/jvim.16895 

Bottom line — Needs more study. Not great support right now.

Probiotics and Feline Asthma

Feline asthma, characterized by airway eosinophilia, intermittent bronchospasm, airway hyperresponsiveness, mucus hypersecretion, and architectural remodeling, currently lacks a cure and requires lifelong administration of glucocorticoids to suppress ongoing airway inflammation. The disease is believed to be allergic in nature, with both genetic predisposition and environmental exposures inducing a T-helper 2 (TH2)-mediated response against specific aeroallergens. Allergen-specific TH2 cells produce cytokines like IL-4, IL-5, and IL-13, leading to sustained local inflammation. 

Respiratory microbiota, recognized for their role in health and disease, are distinct and complex bacterial populations found in the airways of both people and cats. Dysbiosis, or disruption of these commensal microbiota, can lead to overgrowth of pathogens, loss of microbial diversity, and chronic inflammation, which are linked to respiratory diseases such as asthma. 

Studies have shown that both experimental and spontaneously asthmatic cats exhibit respiratory dysbiosis, with significant changes in microbial community structure. Research on healthy cats administered with oral multistrain probiotics indicated significant changes in the microbial composition of their lower airways, suggesting that probiotics might be a potential therapy for respiratory dysbiosis in feline asthma. 

A study aimed to investigate the effects of oral multistrain probiotics versus placebo in asthmatic cats treated with anti-inflammatory doses of glucocorticoids. The hypothesis was that probiotics would attenuate the asthmatic phenotype, increase microbial richness and diversity, and alter immune markers. However, the study found that probiotics did not significantly improve clinical signs, alter microbial communities, or modify immune markers compared to the placebo. 

Diagnosis of feline asthma in the study was based on eosinophilia (≥ 10%) in bronchoalveolar lavage fluid (BALF) cytology after ruling out other respiratory diseases. The study also highlighted that glucocorticoids are essential for managing asthma but can obscure the effects of probiotics. Despite improvement in clinical signs, subclinical inflammation can persist, leading to airway remodeling and worsening disease. 

The study concluded that the administration of oral multistrain probiotics did not effectively manage the asthmatic phenotype or alter microbial and immune profiles in asthmatic cats. Future research should consider larger sample sizes, longer treatment durations, different probiotic formulations or administration routes, and potential steroid-sparing effects of probiotics. 

Remaks, J. D., Vientos-Plotts, A. I., Rindt, H., McAdams, Z., Ericsson, A. C., & Reinero, C. R. (2024). Multistrain probiotics fail to modulate the asthmatic phenotype, respiratory microbiota, and immune responses in cats. American Journal of Veterinary Research https://doi.org/10.2460/ajvr.23.12.0271 

Bottom Line — Did not help in this study.

Standardized Functional Mobility Testing for Dogs

In the United States, a substantial percentage of dogs (30-50%) are considered geriatric, with aging leading to reduced functional reserve and a higher risk of comorbidities that impair mobility, such as sarcopenia and obesity. Standardized clinical functional tests used in human geriatrics to measure physical attributes like strength and balance are scarce for canine geriatrics. This study aimed to assess interrater agreement and criterion validity of a proposed geriatric functional scoring (GFS) framework for dogs, which includes four tasks: TUG, cavallettis, figure 8s, and down to stands. The study also sought to correlate GFS and sTUG (timed up and go) with established client-specific outcome measures (CSOMs) like CBPI and LOAD, differentiate highly functional from less functional dogs based on these scores, and explore relationships between signalment, muscle condition score (MCS), body condition score (BCS), and mobility. 

The findings revealed strong interrater agreement for all tests and the overall GFS, with sTUG showing the highest agreement, making it the most reliable test. Both GFS and sTUG correlated with CBPI and LOAD, indicating their effectiveness in reflecting pain status, function, and quality of life in dogs. The TUG and figure 8s tests were particularly significant in these correlations. It was found that dogs completing the TUG in under 3.83 seconds were considered highly functional. Lower MCS, indicating muscle loss, correlated with higher sTUG, suggesting worse mobility, while BCS did not significantly correlate with sTUG. These results support the use of sTUG as a reliable, practical test for assessing geriatric mobility in dogs and suggest that it can distinguish between different functional levels and is influenced by muscle condition and age. Future research should focus on the repeatability of these tests and further explore the clinical applications of sTUG for prognosis and treatment monitoring. 

McMullin, K. M., Carney, P. C., Juran, I. G., Venator, K. R., Miller, A. V., Lenfest, M. I., Carr, B. J., & Frye, C. W. (2024). Timed up and go demonstrates strong interrater agreement and criterion validity as a functional test in geriatric dogs. American Journal of Veterinary Research https://doi.org/10.2460/ajvr.24.03.0062 

Bottom line — Practical test that might help.

Just putting things in perspective …

Volum