Pulmonary hypertension (PH), a rare condition in cats, has been associated with heartworm infection, thromboembolic disorders, atypical inflammatory polyps, and reversed patent ductus arteriosus. The cat in this report was a 13-year-old female with a history of subcutaneous fibrosarcoma that became acutely dyspneic following concurrent administration of radiotherapy and intravenous carboplatin. Right ventricular dysfunction and congestive heart failure associated with precapillary PH were diagnosed. Pulmonary thromboembolism (PTE) with associated disseminated intravascular coagulation (DIC) was considered to be the most likely underlying disorder. The cat was aggressively treated for the next 15 days with oxygen, benazepril, furosemide, low-dose aspirin, unfractionated heparin, and intravenous fluid therapy. On day 25, the cat was found to be in good health and echocardiography was unremarkable. Possible risk factors for PTE in this cat were neoplasia, use of an indwelling catheter for administration of carboplatin, and DIC. To the authors’ knowledge, this is the first known report of reversible PH, likely secondary to PTE, in a cat.

The diagnosis of PTE can be very frustrating as the patients often present in severe respiratory distress without diagnostic radiographic findings. This case report is a good example of how echocardiographic findings can support a diagnosis of PTE. If tricuspid regurgitation is found, the presence and severity of PH can be determined. In the absence of tricuspid regurgitation, other findings (changes in the pulmonic outflow velocity waveforms, septal flattening, right-sided heart enlargement) may be suggestive of PH, which could help support a diagnosis of PTE. As illustrated in this report, serial echocardiography can be helpful to monitor response to therapy and resolution of PH.
Elizabeth Cole, DVM, Diplomate ACVIM

Reversible pulmonary hypertension in a cat. Toaldo MB, Guglielmini C, Diana A, et al. J SMALL ANIM PRACT 52:271-277, 2011.