Protective effects of omega-3 fatty acids in dogs with myxomatous mitral valve disease stages B2 and C.

Myxomatous mitral valve disease (MMVD) is characterized by thickening of the valve leaflets and omega-3 (ω-3) supplementation has been associated with modulation of blood pressure (BP) and heart rate, improvement of doppler echocardiographic indices, antiarrhythmic, anti-inflammatory and anti-dislipidemic effects in dogs and humans, although prospective studies of it single use are still absent in the veterinary literature. The objective of this study was to evaluate the influence of ω-3 supplementation in dogs with MMVD. Twenty-nine dogs were followed quarterly for 12 months by clinical evaluation, arterial blood pressure, electrocardiography, doppler echocardiography, thoracic radiography and laboratory tests including inflammatory mediators and cardiac biomarker blood concentrations. The dogs were classified in stages B2 and C, according to the classification proposed by ACVIM 2019. They were randomly assigned to either ω-3 group (ω-3G) or control group (CG). The ingestion of ω-3 reduced the chance of developing arrhythmias by 2.96 times (p = 0.003). The vertebral heart size (VHS) measurements were higher in the control group (p = 0.033). In conclusion, at the dosages used in this study, ω-3 dietary supplementation reduces the volumetric overload, has antiarrhythmic effect and keeps dogs with B2 and C stages of MMVD in milder stages of the disease.

Ocular perfusion pressure and color Doppler imaging of the external ophthalmic artery of rabbits treated with sildenafil citrate.

BACKGROUND: It has been proposed that sildenafil citrate can increase ocular blood flow, and that this property can be used to treat ocular disorders that involve reflex vasoconstriction. This study therefore proposes to ascertain the vasodilator effect of the drug on retrobulbar circulation in healthy rabbits. For this matter rabbits treated with sildenafil citrate or saline solution had their intraocular pressure (IOP), mean arterial pressure (MAP), ocular perfusion pressure (OPP) and color Doppler imaging of the external ophthalmic artery measured prior to treatment and on days one (moment M1), seven (when M2), fourteen (moment M3), twenty-one (moment M4), and thirty (moment M5) of treatment. RESULTS: The MAP and OPP values of treated group were lower than those of control group at all times, and the mean values differed statistically at moments M1 (S = 71.52 mmHg, C = 84.76 mmHg, p = 0.0356) and M5 (S = 71.38 mmHg, C = 85.52 mmHg, p = 0.0252). The IOP and color Doppler values of the external ophthalmic artery did not differ between tested groups. CONCLUSIONS: The dose of 10 mg of sildenafil citrate administered to healthy rabbits causes systemic vasodilation and consequently lower values of MAP and OPP. However, it does not induce changes in IOP and retrobulbar hemodynamics identifiable by color Doppler assessment of the external ophthalmic artery.

Sildenafil citrate on retrobulbar and retinal circulation of rabbits / Citrato de sildenafil sobre a circulação retrobulbar e retiniana de coelhos

The effects of sildenafil on retrobulbar and retinal circulation were studied in 18 adult male, albino, homozygous rabbits, of the New Zealand White breed, randomly divided into 3 groups of 6 animals, for drug treatment at a dose of 3.5mg kg-1 every 24 hours, for 7, 15 and 30 days. Nine animals used for control were treated with saline solution at 0.9%. It was evaluated intraocular pressure (IOP), mean arterial pressure (MAP), ocular perfusion pressure (PPO), B-mode ultrasonography and fluorescein angiography before and at the end of treatments. A slight decrease in results of IOP, MAP and PPO after treatment with sildenafil was evident, however, there was no statistical significance. It was observed significant increased diameter of the ophthalmic artery after 7 and 30 days of treatment and decreased mean arterial pressure after 7, 15 and 30 days of treatment, with no statistical difference. On fluorescein angiography, it was observed that the arterial, arteriovenous and venous stages initiated more rapidly in animals after treatment, with significant difference on the arteriovenous stage at the 7th and 15th days. It was possible to admit that the sildenafil citrate improves blood circulation in the retina of rabbits, by increasing the speed of blood flow and decreasing the perfusion pressure.

Os efeitos do sildenafil sobre a circulação retrobulbar e a retiniana foram estudados em 18 coelhos machos adultos, albinos, homozigotos, da raça Nova Zelândia Branco, distribuídos aleatoriamente em 3 grupos de 6 animais, para tratamento com o fármaco na dose de 3,5mg kg-1 a cada 24 horas, por 7, 15 e 30 dias. Nove animais foram utilizados para controle, tratados com solução fisiológica a 0.9%. Foram avaliadas a pressão intraocular (PIO), a pressão arterial média (PAM) e a pressão de perfusão ocular (PPO), ultrassonografia em modo-B e a angiografia fluoresceínica, antes e ao término dos tratamentos. Evidenciou-se discreta diminuição nos resultados da PIO, da PAM e da PPO após tratamento com sildenafil, entretanto não houve significância estatística. Observou-se aumento significativo do diâmetro da artéria oftálmica após 7 e 30 dias de tratamento e diminuição da pressão arterial média após 7, 15 e 30 dias de tratamento, sem diferença estatística. À angiografia fluoresceínica, observou-se que as fases arterial, artério-venosa e venosa iniciaram-se mais rapidamente nos animais após o tratamento, com diferença significativa na fase artério-venosa ao 7o e 15o dias. Foi possível admitir que o citrato de sildenafil melhora a circulação de sangue na retina de coelhos, através do aumento da velocidade do fluxo de sangue e diminuição da pressão de perfusão.