Resistance in equine eye ulcers

Hey, Summarians 🙂 

I am a vet in the Seattle area. My goal with VetSummary is to provide examples of current animal studies that focus on dogs, cats, and horses. Depending on current research, it may have more of one species than another. Hopefully, you will find some nugget of information that you can use or file away.

Please give me feedback on ways I can make it more useful to you.

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

Permethrin tick control in horses

Ticks are a common problem for horses in the US, and they can transmit diseases like Lyme disease and equine anaplasmosis. Chemical sprays with permethrin are commonly used to control or repel ticks and biting insects, but their safety and efficacy on horses are not fully understood. A study evaluated the dermal responses to permethrin at different concentrations on horses' bodies and faces and conducted tick bioassays to compare the effectiveness and longevity of permethrin at different concentrations against ticks.The study found that higher concentrations of permethrin caused greater dermal damage in horses, with visible skin swelling and redness occurring when using the 5% and 10% permethrin on the first day of application. However, permethrin was effective at repelling and killing ticks and biting insects, and initial treatments for 5% and 10% permethrin were more effective than the control at repelling ticks. Precipitation and time postapplication of permethrin influenced tick repellency.The study highlights the importance of equine health and welfare when considering tick repellents, and horse owners should not exceed the recommended permethrin concentrations per the manufacturers' guidelines to avoid unintended health effects on their animals. Additional tick control methods for horses, including low-risk repellents and other on-horse or environmental protective measures, are needed.

Poh, K. C., Cole, Z. T., Smarsh, D. N., Springer, H. R., Kelly, K., Kenny, L. B., & Machtinger, E. T. (2022). Topical permethrin may increase blacklegged tick (Ixodes scapularis) repellency but is associated with cutaneous irritation in horses, American Journal of Veterinary Research (published online ahead of print 2022). Retrieved Feb 22, 2023, from https://avmajournals.avma.org/view/journals/ajvr/aop/ajvr.22.10.0176/ajvr.22.10.017 

Bottom line — Permethrin can work but at what price? Consider alternatives …

Healthspan Assessment for Dogs.

This study evaluated the validity of two healthspan assessment tools, the Canine Frailty Index (CFI) and VetMetrica health-related quality of life (HRQL) instrument, in measuring frailty and health-related quality of life in companion dogs. The study found that older dogs had higher CFI scores and lower HRQL scores, particularly in the domains of energy and enthusiasm, happiness and contentment, and physical activity and comfort. The study also found an inverse relationship between CFI and HRQL scores, even after adjusting for age. Additionally, the study explored size-related differences in CFI and HRQL scores and found that while there were no significant differences in overall scores between large and small dogs, there were differences in specific CFI diseases and deficits. The study concludes that the CFI and VetMetrica HRQL can provide complementary readouts of age-associated declines and healthspan in companion dogs, and that exploring size-related differences in age-associated diseases may provide insights into differences in healthspan among different breeds and sizes of dogs. 

Chen, F.L., Ullal, T.V., Graves, J.L. et al. Evaluating instruments for assessing healthspan: a multi-center cross-sectional study on health-related quality of life (HRQL) and frailty in the companion dog. GeroScience (2023). https://doi.org/10.1007/s11357-023-00744-2 

Bottom line — Good tools for metrics to help assess progress in treatment plans

Stats for Equine Eye Ulcers

This article discusses the common causes, clinical signs, and bacterial isolates associated with equine corneal ulceration, as well as emerging antimicrobial resistance. It presents the findings of a study conducted in a referral veterinary teaching hospital in Australia, which aimed to describe bacterial isolates associated with equine ulcerative keratitis and their antimicrobial susceptibility profile. The study found Pseudomonas species to be the most common bacterial isolate, followed by Streptococcus equi subspecies zooepidemicus and Actinobacillus spp. The study also identified high resistance to some antimicrobials, including gentamicin, neomycin, and polymyxin B. The article concludes that while the study provides new information on equine corneal ulcers in Australia, further research is required due to the small sample size. Aminoglycosides remain the recommended first-line treatment options, with beta-lactams or cephalosporins prescribed if Streptococcus equi subspecies zooepidemicus is isolated, and fluoroquinolones recommended for gentamicin-resistant Pseudomonas spp 

 Deniaud, M. and Tee, E., Susceptibility pattern of bacterial isolates in equine ulcerative keratitis: Implications for empirical treatment at a university teaching hospital in Sydney. Aust Vet J. 2023; 101: 115– 120. https://doi.org/10.1111/avj.13221 

Bottom line — Important to anticipate problems with respect to this information

Just putting things in perspective …