PSIX-6 TXB2, a marker of inflammation, increases with aging and chronic disease, and decreases when cats and dogs are fed omega-3 fats.

Abstract Thromboxane A2 plays a role in many inflammatory conditions, and can be assessed by measuring its metabolite 11-dehydrothromboxane B2 (TXB2). Chronic inflammatory conditions challenge veterinarians, hence the value in biomarkers as tools for monitoring. We assessed the association of TXB2 with inflammation in cats and dogs, and investigated whether dietary intervention with EPA and DHA, ω-3 fatty acids, would provide an anti-inflammatory effect. A cross-sectional study assessed TXB2 in 69 dogs (47 female, 22 male, 1.9-12.7 years) and 70 cats (41 female, 29 male, 1.4-14 years). Urine, collected via cystocentesis, was analyzed by ELISA, normalized to urine creatinine, Log2 transformed before independent t-test, and a priori significance set at p< 0.05. Chronic inflammatory conditions identified in the cohort included joint-issues (hip dysplasia, spondylosis, osteoarthritis, and cruciate rupture), skin disorders (alopecia, dermatitis, pododermatitis, and seborrhea), cardiovascular disorders (heart murmur and hypertrophic cardiomyopathy), hyperthyroidism, and hypoadrenocorticism. Dogs with chronic inflammatory conditions had higher TXB2 (n=36; 1728 + 557 pg/mg) than those without (n=33; 1588 + 723 pg/mg) though not significantly different. Dog health conditions with significantly increased levels of TXB2 were those with seizures and oral-issues. Cats with chronic inflammatory conditions had significantly increased TXB2 values (n=25, 457 + 29 pg/mg) than those without (n=45, 326 + 22 pg/mg). Cat health conditions with significantly increased TXB2 were those with joint-issues, cardiovascular-disorders, and oral-issues. TXB2 positively correlated with age in dogs and cats. In a dietary intervention study, 10 dogs and 12 cats were fed diets with and without EPA-DHA, fatty acids known to have anti-inflammatory effects for 14 days. (canine foods with: EPA=0.40%, DHA=0.26%; feline foods with: EPA=0.46%, DHA=0.30%), Free-catch urine was collected on day 14 of feeding, and TXB2 was analyzed. TXB2 was decreased in dogs fed EPA-DHA by 36% (p< 0.001) when compared to controls. Similarly TXB2 was also reduced in cats fed EPA-DHA by 11% when compared to control (p< < 0.001). In conclusion, urinary TXB2 levels are a good biomarker for assessing inflammatory conditions. Dogs exhibited higher TXB2 levels than cats and had a stronger response to EPA-DHA supplementation. Importantly our results indicate an anti-inflammatory effect of EPA-DHA in companion animals potentially leading to better diagnostics and nutritional interventions.