Aqueous humor fibrinolytic activity in dogs with cataracts.

Objective: To investigate fibrinolytic activity in aqueous humor (AH) of healthy and sick dogs, with and without cataracts.

Procedure: Prospective observational clinical study. A total of 45 dogs were included in the study. Physical and ophthalmic examinations, complete blood cell count (CBC) and serum biochemistry panel were performed in all animals. According to the ocular and systemic diagnoses, animals were classified into three groups: sick dogs without cataracts (20 dogs; 40 eyes), diabetic dogs with cataracts (11 dogs; 22 eyes), and healthy dogs with cataracts (14 dogs; 25 eyes). Bilateral AH and blood samples were collected during intraocular surgery (25 dogs; 47 eyes), or immediately after euthanasia (20 dogs; 40 eyes). Citrated samples were centrifuged and stored at -81 °C until analysis. Plasma and AH D-dimer concentration were determined using a quantitative immunoturbidimetric latex agglutination assay.

Results: A total of 108 canine samples (45 plasma and 87 AH samples) were obtained. D-dimer concentration in log-scale, in AH of eyes with diabetic cataract was significantly higher than AH of eyes with nondiabetic cataract, with a difference of 0.9 ng/mL 95% confidence interval (CI) (0.2; 1.6) P = 0.0116 and higher than that of sick animals with healthy eyes, with a estimated difference of -0.89 ng/mL 95% CI (-1.52; -0.25) P = 0.0061. Plasma D-dimer concentration was significantly higher in the group of animals with systemic disease [median 606 ng/mL, Interquartil Range (IQR) 145-1956 ng/mL] than in healthy dogs (median 47.5 ng/mL, IQR 4-250 ng/mL) (P = 0.002) and diabetic dogs (median 60.5 ng/mL, IQR 0-147.5 ng/mL) (P < 0.001).

Conclusion: AH fibrinolysis is present in dogs, being significantly higher in animals with diabetic cataracts than in those without cataracts, and those with nondiabetic cataracts.