Constrictive physiology is not present in all dogs with idiopathic chylothorax

To determine whether subtotal pericardectomy affects recurrence and long-term outcomes in dogs with idiopathic chylothorax (IC).

12 client-owned dogs diagnosed with IC between July 26, 2016, and March 23, 2023.

The diagnosis of constrictive physiology (CP) was established with cardiac catheterization and defined as elevated and equal diastolic pressures in all 4 cardiac chambers. Dogs were then entered into the constrictive physiology (CP) group or non-CP (NCP) group. All dogs received at least a thoracic duct ligation (TDL). The dogs in the CP group had a subtotal pericardectomy performed in addition to TDL. Repeated surgical interventions, recurrence, long-term outcomes, and survival times were recorded.

8 dogs were entered into the CP group and underwent TDL and subtotal pericardectomy. Four dogs were entered in the NCP group and underwent only a TDL. Four dogs in the CP group and 1 in the NCP group required multiple surgeries for recurrent chylothorax. The 1-, 2-, and 3-year disease-free rates were, respectively, 100%, 100%, and 50% for the NCP group and 87.5%, 72.9%, and 72.9% for the CP group (P = .935). The 1-, 2-, and 3-year survival rates were, respectively, 100%, 100%, and 100% for the NCP group and 87.5%, 72.9%, and 72.9% for the CP group (P = .317).

Constrictive physiology should be evaluated by cardiac catheterization before surgical treatment of IC in dogs. If CP is not diagnosed, subtotal pericardectomy may not be required.