Chylothorax

ChylothoraxChylothorax

Dr. Rekha Pathak (Sr. Scientist)Division of Surgery,Indian Veterinary Research Institute, Izatnagar, Bareilly, India

Duct – dorsal Duct – dorsal mediastinum – close to mediastinum – close to vertebral bodiesvertebral bodies

Passes cranially from Passes cranially from the cisterna chyle- on the cisterna chyle- on the rt. Side of aorta- 6the rt. Side of aorta- 6thth thoracic vertebra- thoracic vertebra- crosses to left of crosses to left of oesophagus- continues oesophagus- continues cranially – thoracic cranially – thoracic inlet- turns ventrally inlet- turns ventrally and enters the left and enters the left brachiocephalic vein. brachiocephalic vein.

Chylothorax in dogs and Chylothorax in dogs and catscats

Chylothorax – chyle(a Chylothorax – chyle(a high concentration of high concentration of chylomicrons and chylomicrons and lymph) -effuses from lymph) -effuses from the thoracic ductthe thoracic duct

Chylothorax is fairly Chylothorax is fairly uncommon in dogs uncommon in dogs and cats, is usually and cats, is usually secondary to other secondary to other conditions or conditions or diseases, and can be diseases, and can be difficult to treat. difficult to treat.

Chylous effusion Chylous effusion - milky-white pleural - milky-white pleural

fluid fluid - fails to become clear - fails to become clear

upon centrifugation. upon centrifugation.

Pseudochylous effusion - Pseudochylous effusion - chronic inflammatory chronic inflammatory thoracic disease. thoracic disease.

Pseudochylous effusions Pseudochylous effusions do not contain do not contain chylomicra, clear upon chylomicra, clear upon centrifugation, centrifugation,

Dietary lipids- break to form Dietary lipids- break to form chylomicrons chylomicrons – finally absorbed by – finally absorbed by lymphatics (chyle)- carried to lymphatics (chyle)- carried to different body parts. different body parts.

Chylous effusions Chylous effusions may result from may result from leakage of chyle leakage of chyle from intact from intact lymph vessels or lymph vessels or

thoracic duct thoracic duct perforation. perforation.

Obstruction of Obstruction of lymphatic flow lymphatic flow commonly causes commonly causes lymphatic lymphatic hypertension, hypertension,

dilation of dilation of lymphatics, and lymphatics, and subsequent subsequent leakage of lymph. leakage of lymph.

Different causes for Different causes for chylothorax in dogschylothorax in dogs

Congenital Congenital abnormalities of abnormalities of the thoracic duct the thoracic duct

Diaphragmatic Diaphragmatic hernia hernia

Fungal infections Fungal infections Heartworm Heartworm

disease disease IdiopathicIdiopathic Violent Violent

coughing/vomiting coughing/vomiting . .

Lung lobe torsion Lung lobe torsion Lymphangiectasia Lymphangiectasia Neoplasia Neoplasia Trauma and Trauma and

rupture of thoracic rupture of thoracic duct duct

Venous thrombi Venous thrombi Mediastinal Mediastinal

neoplasianeoplasia

Incidence:Incidence: No genderNo gender predisposition predisposition Age Age does seem to be a factor, does seem to be a factor,

1.1. trauma-related, trauma-related,

2.2. idiopathic, and idiopathic, and

3.3. congenital causes of chylothorax congenital causes of chylothorax tend to occur in younger dogs. tend to occur in younger dogs.

Chylothorax associated with Chylothorax associated with neoplasia and heart disease neoplasia and heart disease tend to occur in older animals. tend to occur in older animals.

A breed predispositionA breed predisposition purebred cats, purebred cats, Afghan Hounds, and Afghan Hounds, and MastiffsMastiffs

DiagnosisDiagnosis

Diagnosis is made based on Diagnosis is made based on

Physical examination, Physical examination, Clinical signs, Clinical signs, Thoracic radiographs, and Thoracic radiographs, and Pleural fluid analysisPleural fluid analysis. .

DiagnosisDiagnosis

1.1. clinical signs,clinical signs,

dyspnea and coughing. dyspnea and coughing. weight loss, weight loss, anorexia, lethargyanorexia, lethargy

regurgitation, regurgitation, vomiting, vomiting, exercise intolerance, and exercise intolerance, and

salivation. Abnormal physical salivation. Abnormal physical findings most commonly findings most commonly include dyspnea, muffled include dyspnea, muffled heart sounds, heart sounds,

DiagnosisDiagnosis

Physical examination,Physical examination, Bronchovesicular sounds, and Bronchovesicular sounds, and

tachycardia. tachycardia.

Thoracic radiographsThoracic radiographs Radiographs typically reveal Radiographs typically reveal

pleural effusion which may be pleural effusion which may be unilateral or bilateral, unilateral or bilateral,

Imaging StudiesImaging Studies Chest radiographic findings are nonspecific for Chest radiographic findings are nonspecific for

chylothorax and indistinguishable from other causes of chylothorax and indistinguishable from other causes of pleural effusion. pleural effusion. Determine if effusion is bilateral. Determine if effusion is bilateral. Look for a mediastinal shift.Look for a mediastinal shift.

Left sided effusionsLeft sided effusions

. Ultrasonography and . Ultrasonography and echocardiography may be useful echocardiography may be useful in identifying an underlying in identifying an underlying cause of the effusion, such as cause of the effusion, such as cardiomyopathy or mediastinal cardiomyopathy or mediastinal neoplasia.neoplasia.

Lab diagnosisLab diagnosis

The complete blood count The complete blood count

mature neutrophilia due to mature neutrophilia due to inflammation inflammation

lymphopenia from the loss of lymphopenia from the loss of lymphocytes into the fluid.lymphocytes into the fluid.

The serum chemistry profileThe serum chemistry profile

Hypoalbuminemia,- protein loss in Hypoalbuminemia,- protein loss in the fluidthe fluid

Hyponatremia- electrolyte loss in Hyponatremia- electrolyte loss in fluidfluid

Hyperkalemia. Hyperkalemia may Hyperkalemia. Hyperkalemia may be due to hypovolemia and/or renal be due to hypovolemia and/or renal secretion defects of potassium. secretion defects of potassium.

Pleural fluid Pleural fluid analysis is required analysis is required for the diagnosis of for the diagnosis of chylothorax. chylothorax. Grossly, chylous Grossly, chylous effusion is milky effusion is milky white or pink, white or pink, depending on the depending on the degree of degree of hemorrhage hemorrhage associated with the associated with the effusion effusion

Chylous Chylous effusions effusions should not should not clot or have clot or have an odor, and an odor, and should be free should be free of particulate of particulate matter.matter.

Collecting Collecting the fluid into the fluid into an EDTA an EDTA tube allows tube allows for cell for cell counts on the counts on the samplesample. .

A culture and sensitivityA culture and sensitivity

The effusion should form a cream layer The effusion should form a cream layer

Upon centrifugation, the sample should Upon centrifugation, the sample should become white following centrifugation if become white following centrifugation if red blood cells are present (although the red blood cells are present (although the presence of hemolyzed erythrocytes will presence of hemolyzed erythrocytes will result in a fluid that remains red or pink result in a fluid that remains red or pink following centrifugation), and should following centrifugation), and should remain opaque. remain opaque.

Cytologic and Chemical Cytologic and Chemical CharacteristicsCharacteristics

Laboratory analyses that may be Laboratory analyses that may be performed on the fluid include performed on the fluid include determination of determination of

specific gravity, specific gravity, TPTP TLC,DLCTLC,DLC cholesterol and triglyceride cholesterol and triglyceride

concentrationsconcentrations ratio of cholesterol to triglyceride. ratio of cholesterol to triglyceride.

Predominance of small Predominance of small lymphocytes - lymphocytes - considered considered characteristic of chylous characteristic of chylous effusion; effusion;

However, increase in However, increase in neutrophils and neutrophils and macrophages may be macrophages may be associated with associated with chronicity.(chyle is chronicity.(chyle is irritant to pleura) irritant to pleura)

Pseudochylothorax Pseudochylothorax Chylothorax must be distinguished Chylothorax must be distinguished

from pseudochylothorax, or from pseudochylothorax, or cholesterol pleurisy, which results cholesterol pleurisy, which results from accumulation of cholesterol from accumulation of cholesterol crystals in a chronic existing crystals in a chronic existing effusion. effusion.

The most common cause of The most common cause of pseudochylothorax is chronic pseudochylothorax is chronic pneumonia, pleuritis and pneumonia, pleuritis and lymphosarcomalymphosarcoma

Serum/chylous/Serum/chylous/pseudochylous pseudochylous

. Chylous effusions . Chylous effusions Less cholesterol more triglycerides Less cholesterol more triglycerides

than serum C:T= <1than serum C:T= <1 Fluid: serum triglycerides = >3:1, Fluid: serum triglycerides = >3:1, Usually encountered 10-20:1Usually encountered 10-20:1

Pseudochylous – more cholesterol and Pseudochylous – more cholesterol and triglycerides less or equal to serumtriglycerides less or equal to serum

An ether clearance testAn ether clearance test take effusion in 2 tubes+ 10% KOH take effusion in 2 tubes+ 10% KOH First tube+equal water (control) First tube+equal water (control) Second tube+equal ether Second tube+equal ether Invert- chylomicrons dissolve Invert- chylomicrons dissolve

completely in ethercompletely in ether The first tube should appear diluted, The first tube should appear diluted,

but second tube should become clear. but second tube should become clear. This test is not routinely performed. This test is not routinely performed.

Treatment and PrognosisTreatment and Prognosis

depends on the underlying causedepends on the underlying cause

Medical therapy:Medical therapy:

Thoracocentesis-needle/ chest tube Thoracocentesis-needle/ chest tube drainagedrainage

Dietary management- low fat diet-to Dietary management- low fat diet-to decrease lipids in intestinal absorptiondecrease lipids in intestinal absorption

Drug therapyDrug therapy

loss of fat-soluble vitamins, lipids, and loss of fat-soluble vitamins, lipids, and protein-rich lymph fluid may protein-rich lymph fluid may contribute to a state of contribute to a state of malnourishment in the animal.malnourishment in the animal.

Parenteral nutrition can bypass the Parenteral nutrition can bypass the gastrointestinal system and decrease gastrointestinal system and decrease lymphatic flow. lymphatic flow.

Surgical managementSurgical management

Not v. successfulNot v. successful ligation of the thoracic duct-feed ligation of the thoracic duct-feed

fat/oil prior- canulate superficial fat/oil prior- canulate superficial lymphatic in hindlimb- inject dye- lymphatic in hindlimb- inject dye- locate the duct and point of rupturelocate the duct and point of rupture

1% Evans blue dye can either be 1% Evans blue dye can either be injected into the web space of injected into the web space of the toes for uptake into the the toes for uptake into the lymphatic space to increase lymphatic space to increase visualization.visualization.

99th th i.c.(right) space-an open right i.c.(right) space-an open right thoracotomy or through a thoracoscope. thoracotomy or through a thoracoscope.

locate duct- ligate cranial and caudal to locate duct- ligate cranial and caudal to rupturerupture

Collaterals buildCollaterals build Place the chest tube and close Place the chest tube and close pleuroperitoneal or pleurovenous shunts. pleuroperitoneal or pleurovenous shunts.

Positive contrast mesenteric Positive contrast mesenteric lymphangiography is useful to lymphangiography is useful to determine lymphatic anatomy and determine lymphatic anatomy and post-ligation success.post-ligation success.

Pleuroperitoneal or pleurovenous Pleuroperitoneal or pleurovenous shunts may be beneficial, but are shunts may be beneficial, but are associated with complications such as associated with complications such as infection, adhesions, and clogging of infection, adhesions, and clogging of the implantsthe implants

Poor prognosis Poor prognosis

Regardless of the cause, chylothorax Regardless of the cause, chylothorax has been associated with poor has been associated with poor survival rates in dogs and cats.survival rates in dogs and cats.

A common sequela to chylothorax is A common sequela to chylothorax is restrictive pleuritis, resulting in an restrictive pleuritis, resulting in an inability to expand the lungs. inability to expand the lungs.