Retrospective Evaluation of Sildenafil Citrate as a Therapy for Pulmonary Hypertension in Dogs

Abstract

Pulmonary arterial hypertension (PH) is a pathologic condition in dogs characterized by abnormally high pressures in the pulmonary circulation and has been associated with a poor outcome. Sildenafil is a type V phosphodiesterase inhibitor that produces nitric oxide mediated vasodilatation. Sildenafil treatment decreases pulmonary arterial pressure and pulmonary vascular resistance in people with PH. The purpose of this study was to describe the clinical characteristics and outcome of dogs with PH treated with sildenafil. The cardiology database was searched for dogs with PH treated with sildenafil. PH was defined as systolic pulmonary arterial pressure (PAPs) > or = 25 mmHg at rest. Medical records were reviewed for the following information: signalment, duration and type of clinical signs before treatment, underlying disease, estimated or measured PAPs, dosage and dosing interval of sildenafil, and the effect of treatment on clinical signs and pulmonary arterial pressure and survival time. Thirteen affected dogs were identified. Clinical signs included collapse, syncope, respiratory distress, and cough. Duration of clinical signs before presentation ranged from 3 days to 5 months. An underlying cause was identified in 8 dogs. The median sildenafil dosage was 1.9 mg/kg. Ten dogs received concurrent medications. Median PAPs was 90 mmHg; 8 dogs were reevaluated after therapy, and the median decrease in PAPs was 16.5 mmHg. The median survival time of all dogs was 91 days. Sildenafil appeared to be well tolerated in dogs with PH and was associated with decreased PAPs and amelioration of clinical signs in most. Sildenafil represents a reasonable treatment option for dogs with pulmonary hypertension.

Efficacy of sildenafil therapy for pulmonary hypertension in dogs: a systematic review

“…before and after treatment. In addition to measures of systolic pressure, Bach et al (2006) showed increased diastolic blood pressure values after treatment with sildenafil, although this increase was not statistically significant. The administration of other drugs in addition of sildenafil occurred in three studies, of which the angiotensin converting enzyme (ACE) inhibitors furosemide and spironolactone were the most commonly used.…”

“…Systolic blood pressure (systemic) (SBP) was measured in three of five selected papers (Bach et al 2006, Kellum and Stepien 2007, Brown et al 2010. In all studies, the SBP values were higher before the start of treatment with sildenafil, given that after the period of therapy SBP was numerically lower, but statistically there was no difference Table 1.…”

“…Only one study had more than 20 animals (Kellum and Stepien 2007); three studies used between 5 and 19 animals of which two used 13 (Bach et al 2006, Brown et al 2010 and one 5 animals (Nakamura et al 2011). One study used only 1 animal (Toyoshima et al 2007).…”

“…The administration of other drugs in addition of sildenafil occurred in three studies, of which the angiotensin converting enzyme (ACE) inhibitors furosemide and spironolactone were the most commonly used. In the study conducted by Bach et al (2006), 77% of the animals were treated with other drugs. Kellum and Stepien (2007) demonstrated the use of other medications in 32% of animals.…”

“…Also, in animals such as piglets (Rondelet et al 2004) and mice (Takimoto et al 2005), important pulmonary and cardiac effects of sildenafil treatment have been demonstrated. On the other hand, few studies in dogs have been conducted to evaluate the efficacy of sildenafil in the treatment of PH (Bach et al 2006, Kellum and Stepien 2007, Brown et al 2010, even though this drug is consistently used in the routine clinical care of small animals.…”