Is Plavix Effective For Cats

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From more esoteric research to very practical topics, our goal is to provide a range of studies to help educate. I hope that you enjoy them.

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Tona-Vera Accuracy in Dogs

This study evaluates the accuracy of the Reichert® Tono-Vera® Vet rebound tonometer for measuring intraocular pressure (IOP) in canine eyes. Five freshly enucleated normal canine eyes were used, with their anterior chambers cannulated and connected to a manometer and a reservoir of Plasma-Lyte A. Starting at a manometric IOP of 5 mmHg, pressure was progressively increased to 80 mmHg. Triplicate IOP measurements were taken with the Tono-Vera® Vet from the central cornea and compared to manometric pressure using linear regression and Bland–Altman plots. 

The results showed a strong linear correlation (r2 = .99) between Tono-Vera® Vet measurements and manometric IOPs, with solid agreement across a range of pressures. However, the Tono-Vera® Vet underestimated IOPs at pressures ≥70 mmHg. Despite this, the underestimation was not deemed clinically significant. The study concluded that the Tono-Vera® Vet provides accurate IOP measurements over a large pressure range in canine eyes, with only a mild to moderate underestimation at high pressures. 

Kapeller LE, Buckman PN, Wang S, Komáromy AM. Validation of the Reichert® Tono-Vera® Vet rebound tonometer in normal ex vivo canine eyes. Vet Ophthalmol. 2024; 27: 290-293. doi:10.1111/vop.13213 

Bottom line — Seems to be quite accurate.

Plavix and Cats

Cats with hypertrophic cardiomyopathy (HCM) have a risk of developing aortic thromboembolism (ATE). Clopidogrel is known to reduce the risk of recurrent ATE and is recommended for cats with severe HCM. However, clopidogrel is unpalatable for cats, making administration difficult. Estimating the potential benefit of clopidogrel can help clinicians decide on a case-by-case basis. Studies show that clopidogrel can reduce the risk of ATE by approximately 3% to 4% in cats with moderate to severe HCM. Given the difficulty of administering the drug, clinicians should weigh these modest benefits against the potential harms, such as the stress of administration, and not necessarily insist on its use. 

Hypertrophic cardiomyopathy is the most common cardiac disease in adult cats. Studies indicate that HCM progresses slowly, with many cats remaining subclinical for years. About 10% of cats have moderate to severe disease, which increases the risk of complications like congestive heart failure (CHF) or ATE. Risk factors for ATE include large left atrial size and poor left atrial function. The FATCAT study found that clopidogrel significantly reduces the recurrence of ATE compared to aspirin. Guidelines recommend clopidogrel for cats at risk of ATE, but it is unpalatable and difficult to administer. 

Evidence-based medicine suggests that the benefits of any intervention should be weighed against the costs or harms. In the case of clopidogrel for cats with HCM, the benefit of a 3% to 4% reduction in ATE risk must be considered against the challenges of administration. The FATCAT study found a relative risk reduction of 35% for recurrent ATE with clopidogrel. Assuming this benefit applies to primary prevention, clopidogrel provides a 3.5% to 4.4% absolute risk reduction. Clinicians need to treat 23 to 29 cats to prevent one ATE event. Therefore, the decision to prescribe clopidogrel should be carefully considered, and it is reasonable for clients to decline its use. 

Rishniw, M. (2024). How much protection does clopidogrel provide to cats with hypertrophic cardiomyopathy?. Journal of the American Veterinary Medical Association https://doi.org/10.2460/javma.24.04.0269 

Bottom line — We may need to consider this carefully.

New Joint Treatment for Horses

Joint disease leading to osteoarthritis (OA) is a prevalent issue in horses, accounting for up to 60% of lameness cases. Despite advancements in managing joint injuries, damage to the articular cartilage frequently results in OA, limiting long-term soundness and athletic performance. Inflammation and pain are common in OA, and treatments often include intra-articular (IA) medications. Corticosteroids are the most common IA treatments, despite their potential adverse effects, including laminitis, joint flares, and cartilage damage. 

Recent studies highlight the role of cyclin-dependent kinase-9 (CDK9) in OA development following joint injury. CDK9 is crucial for the transcription of inflammatory genes involved in OA pathogenesis. Inhibition of CDK9 has shown protective effects against inflammatory cytokines and cartilage degradation in vitro and in animal models. Small-molecule CDK9 inhibitors, like flavopiridol (alvocidib), are primarily developed for cancer treatment but show potential in reducing inflammation in OA. 

This study aimed to evaluate the tolerability and pharmacokinetics of a sustained-release PLGA (poly lactic-co-glycolic acid) formulation of flavopiridol administered via IA injection in equine middle carpal joints. It was hypothesized that IA flavopiridol would achieve detectable levels in synovial fluid with minimal systemic exposure and no significant adverse effects. The study found that IA administration of extended-release flavopiridol-PLGA was well-tolerated, maintaining detectable synovial levels for about four weeks with negligible systemic exposure. There were no observed adverse effects, although a slight increase in synovial fluid cellularity was noted, likely due to repeated arthrocentesis rather than the treatment itself. 

Corticosteroids, commonly used for managing arthritic joints, can have severe systemic side effects due to rapid diffusion into the bloodstream. Formulations like extended-release PLGA aim to minimize these effects by retaining the drug within the joint. CDK9 inhibitors like flavopiridol offer an alternative by targeting inflammatory pathways differently than corticosteroids. 

This study's limitations include a small sample size of four horses, lack of tissue biopsies for histological assessment, and the inability to detect systemic flavopiridol at the given dose. Future research should explore dose escalation and the therapeutic benefits of flavopiridol in joint disease. 

In conclusion, IA injection of extended-release flavopiridol-PLGA is well tolerated in horses, with sustained synovial fluid levels and minimal systemic exposure, suggesting potential as an effective OA treatment. Further studies are needed to confirm its efficacy in joint disease. 

Katzman, S. A., Cissell, D., Leale, D., Perez-Nogues, M., Hall, M. D., Bloom, G., Hamamoto-Hardman, B., Wu, C., Haudenschild, A. K., Liu, G., Yik, J. H. N., & Haudenschild, D. R. (2024). Intra-articular injection of an extended-release flavopiridol formulation represents a potential alternative to other intra-articular medications for treating equine joint disease. American Journal of Veterinary Research https://doi.org/10.2460/ajvr.24.03.0057 

Bottom line — Potentially new treatment option. More research is needed.

Just putting things in perspective …