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Chylothorax 173

microL, total protein > 2.5 g/dL) or a • Traumatic chylothorax can resolve spontane- needle placed into a subcutaneous drainage
ously with only supportive care.
nonseptic exudate (>5000 nucleated • Intermittent thoracocentesis, as respiratory • Active pleuroperitoneal or pleurovenous
hub.
VetBooks.ir ○ Predominant cell type: early chylothorax: signs dictate drainage techniques: disadvantages include Diseases and Disorders
cells/microL, total protein > 2.5 g/dL)
(p. 1343).
cost, thrombosis, catheter obstruction,
○ If frequent thoracocentesis is performed,
small lymphocytes; chronic chylothorax:
abdominal distention (if pleuroperitoneal),
and hyperkalemia can occur.
nondegenerate neutrophils ± macrophages monitor serum electrolytes; hyponatremia, air embolism, venous occlusion, sepsis,
• CBC: ± lymphopenia; changes are rarely ○ If fluid accumulation is rapid, thoracos- and potential lack of owner compliance.
specific tomy tubes may be required. • Pleurodesis and passive pleuroperitoneal
• Serum biochemistry profile: hypocalcemia, • Medical management (idiopathic drainage: not recommended
hypocholesterolemia, and hypoalbuminemia/ chylothorax) • Cisterna chyli ablation combined with TD
hypoproteinemia are possible especially with ○ Low-fat diet (commercial or homemade): ligation has been described as superior to
concurrent lymphangiectasia. Suggested to reduce the flow of chyle, TD ligation alone. Cisterna chyli and TD
• Urinalysis: unremarkable but effect of diet has been questioned. glue embolization has been reported in two
• Heartworm antigen test (± antibody test in Medium-chain triglyceride supplementa- dogs with refractory chylothorax.
cats): rule out infection tion no longer recommended
• Feline retroviral testing: rule out infection ○ Rutin (250-500 mg/CAT or 50 mg/kg PO Possible Complications
• Thyroid testing (all cats > 5 years) q 8-12h): used for treating lymphedema • Incomplete resolution of chylothorax can
in humans and has been used in feline occur with any treatment technique.
Advanced or Confirmatory Testing chylothorax with limited success and no ○ Nonchylus effusions may develop in some
• Echocardiography (p. 1094) to assess for documented adverse effects. patients.
myocardial, valvular, or pericardial disease ○ Octreotide (somatostatin analog): thought • Surgical and anesthetic risks
• Biochemical analysis of pleural fluid: com- to reduce fluid flow through the TD. • Fibrosing pleuritic: pleural thickening by fibrous
pared to serum concentrations, increased Neither efficacy nor dose established; tissue that restricts normal lung expansion
pleural fluid triglyceride and decreased range from 1-20 mcg/kg SQ, IM q 6-8h • Re-expansion pulmonary edema, electrolyte
pleural fluid cholesterol concentrations are • Surgery: optimal timing for surgery is disorders associate with thoracocentesis
consistent with chylous effusion (p. 1343) undetermined, but delaying surgical interven-
○ Pleural/serum triglyceride ratios > 10-20 : 1 tion increases the risk of fibrosis pleuritis. Recommended Monitoring
are common. Because medical management of idiopathic • Clinical signs
○ Pseudochylous effusions (rare): effu- chylothorax has a guarded prognosis, surgical • Thoracic radiographs to assess pleural fluid
sion cholesterol concentration > serum intervention has been suggested as the initial accumulation/resolution
cholesterol concentration, and effusion treatment of choice. Surgical options include • Postoperative patients should also be moni-
triglyceride concentration < the serum TD ligation alone, TD ligation combined tored for reaccumulation of fluid.
triglyceride concentration with pericardectomy or other procedures,
○ In fasted/anorexic animals, pleural fluid and/or cisterna chyli ablation. PROGNOSIS & OUTCOME
may have a reduced triglyceride concentra- TD ligation:
tion and lack milky appearance. Consider • Ligation of the TD and its branches, often • Rarely, spontaneous resolution is reported.
checking postprandial effusion and serum in combination with lymphangiography Resolution is more likely if an underlying
triglyceride concentrations. (TD rupture rarely detected). Used as sole disease can be corrected or after traumatic
• CT ± lymphangiogram or MRI (p. 1132) procedure, reported rate of resolution for TD rupture.
may aid assessment of structural abnormali- dogs 53%, for cats 20%-53% • For patients with idiopathic chylothorax
ties in the thoracic cavity. ○ Intercostal or transdiaphragmatic approach or thoracic lymphangiectasia, TD ligation
○ Percutaneous popliteal lymphangiograms most common or less often by median combined with pericardectomy and/or cisterna
have been performed. sternotomy chyli ablation appears to offer the best results.
○ Lymphangiography repeated after ligation Early surgical referral is warranted.
TREATMENT to ensure all branches have been ligated • After fibrosing pleuritis has developed, the
○ Thoracoscopic TD ligation combined with prognosis worsens regardless of treatment.
Treatment Overview mesenteric lymphangiography has been
Treatment goals: alleviate respiratory distress described. PEARLS & CONSIDERATIONS
when present and treat an underlying cause TD ligation combined with other procedures:
when possible • TD ligation with pericardectomy: Comments
○ A thickened pericardium may increase • Cats with pleural effusion are fragile and
Acute General Treatment right-sided venous pressures, impeding must be handled carefully (e.g., during
• Oxygen if respiratory distress (p. 1146) drainage of chyle. restraint); the degree of resting dyspnea
• Thoracocentesis (p. 1164) is the initial ○ Reported success rates approach 100% may be surprisingly mild with large pleural
therapy of choice. for dogs and 80% for cats. effusions in this species.
○ Complete drainage is unnecessary to ○ The addition of omentalization to peri- • Long-standing chylous effusion can lead to
relieve/improve clinical signs and may cardectomy does not appear to improve fibrotic pleural disease, an irreversible cause
be hazardous. outcome. of respiratory impairment.
○ Fibrosing pleuritis limits the degree of ○ TD ligation and pericardial window • Repeated thoracocentesis is not a viable
lung expansion. Re-expansion pulmonary placement or pericardectomy can be long-term solution due to fibrosing pleuritis
edema may occur with complete drainage, performed less invasively with video- that interferes with pulmonary expansion;
particularly if disease is chronic (p. 836). assisted thoracoscopic surgery. fibrosis also leads to fluid pockets, making
• Omentalization: exploits the large surface draining far more difficult.
Chronic Treatment area and lymph-draining capability of the
• Specific treatment of any identified underly- omentum. Technician Tips
ing disease (e.g., CHF, HWD) may resolve • Placement of a PleuralPort device: owners • Animals with pleural effusions can be
chylothorax. can drain the effusion at home using a Huber very fragile and susceptible to stress with

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