1. The Chyle Files: Chylothorax
Abigail Mariano, VMD
Small Animal Surgery Resident
December 20, 2013
Chylothorax is a frustrating condition for clinicians and pet owners alike. As I’ll talk about over the next 40 minutes, there is still a lot we do not know about managing this condition. Its not a common disease, but if you havent seen a case of it yet, odds are that you will.

2. What is it?
Disruption or abnormality of the thoracic duct or tributaries of the lymphatics resulting in accumulation of chyle in pleural space

3. Population Dogs and cats
Breed predispositions: Afghan hounds, Shiba Inus, Oriental cat breeds
No sex predilection
No age predilection
I will be talking about it in dogs and cats, though it has been reported in horses, cows, rats, rabbits, ferrets and most animals. Not very much research in species other than humans, dogs, and cats.
Shiba Inus tend to be <1 year and Afghan and oriental cats middle to older age

4. Presenting clinical signs
Cough
Abnormal respiration
Shallow/restrictive
Tachypnea
Orthopnea
Acute respiratory distress
Cyanosis
Muffled heart/lung sounds
Increased bronchovesicular sounds dorsally
Weight loss
Coughing may be first and only clinical sign in dogs and cats
Orthopnea being when they posture with their elbows abducted and head and neck extended
Can be cyanotic in severe presentations
May have a history of recent or chronic weight loss

5. Effusions Transudate Modified transudate Exudate
<1500 nucleated cells/uL
<2.5 g/dL total protein
Modified transudate
nucleated cells/uL
2.5-4 g/dL total protein
Exudate
>7000 nucleated cells/uL
>3 g/dL total protein
When an animal presents in this condition, in addition to administering oxygen, one of your first diagnostic AND therapeutic steps will be to perform a thoracocentesis.
Collect it in an EDTA anticoagulant tube for cell counts and a red top for biochemical analysis (cholesterol, triglycerides) and save some for culture if indicated by the cell counts
Transudates are clear and are usually the result of a decrease in intravascular oncotic pressure such as hypoalbuminemia
Modified transudates are most commonly due to long standing transudates or an increase in lymphatic or venous hydrostatic pressure
Exudates have a turbid appearance from the increased cell counts, often due to increased vascular permeability
Further effusion classifications include septic or nonseptic inflammation, neoplastic effusion, hemorrhagic effusion, and chylous effusion

6. Chyle
So if you get something back that looks like this, you are most likely dealing with a chylous effusion!
Milky white modified transudate or exudate
Composition: lymph and chylomicrons
Protein content unreliable bc of refractive interference of lipids
Predominant cell type is small lymphocyte, with increasing numbers of neutrophils and macrophages with chronicity

7. As a reminder: chylomicrons are lipoprotein particles that consist of triglycerides, phospholipids, cholesterol, and a small amount of proteins. They enable transport of the dietary fats and cholesterol from the intestines to other locations in the body by making them water soluble. They travel in the lymphatic system and are released into the bloodstream at the TD connection with the vena cava.

8. Fluid diagnostics Cytology, fluid analysis
Paired fluid and serum triglycerides
Cholesterol : Triglyceride ratio
Ether clearance test
Sudan stain for lipid droplets
+/- Culture and sensitivity
In addition to the Cytology and I just described. Other diagnostics are
Pleural triglycerides are often >10 times serum levels
Cholesterol/triglyceride ratio <1 in pleural fluid is diagnostic and helpful in anorectic patients
Ether test: 2 tubes of pleural fluid, alkalinized with 1-2 drops of sodium or potassium hydroxide. Add ether to one tube, water to the other. A positive test is one where the pleural fluid becomes more clear after ether addition. Ether extracts/dissolves the fat
Sudan III is a fat soluble stain that will stain for lipid droplets
Culture and sensitivity may be indicated with repeated taps if iatrogenic infection is suspected. Chylous effusion is bacteriostatic by nature
(Pseudochylous – pleural cholesterol> serum cholesterol. Assoc with tb)

9. Etiopathogenesis Trauma to the thoracic duct (uncommon in animals)
Secondary to ANY condition that causes obstruction of the thoracic duct, prevents lymph flow to venous circulation, or increases in lymphatic flow
Simple version
Chylothorax may result from trauma to the thoracic duct which is uncommon in small animals or it may be secondary to any condition that causes obstruction of the TD or that prevents lymph flow to venous circulation.

10. Etiopathogenesis Cardiac disease (congenital or acquired)
Pericardial disease
Dirofilariasis
Pulmonary hypertension
Lung lobe torsion
Diaphragmatic hernia
Trauma
Neoplasia
Infection (fungal granuloma)
Congenital or acquired abnormalities of the thoracic duct
Venous thrombi
Idiopathic***
Evaluate for underlying disease
Incomplete list….
Cardiac (right sided heart disease, cardiomyopathy, tetralogy of fallot, valvular dysplasia, cor triatriatrum dexer)
Pericardial disease or effusion
Heartworm disease
Pulmonary hypertension
Lung lobe torsion, diaphragmatic hernia or other trauma to the TD
Neoplasia including heart base masses, cranial mediastinal masses, pericardial neoplasia, and lymphangiosarcoma
Infection including Fungal granulomas
Congenital or acquire abnormalities of the TD
Venous thrombi (cranial vena cava) resulting in elevated hydrostatic pressure of cranial vena cava, Obstruction of the lymphaticovenous junction
Idiopathic are most common.
Of all these, chylothorax with a treatable underlying disease carries the best prognosis. Trauma is the #1 cause in people, but is rare in animals. It is associated with a good prognosis- usually mild CS and self limiting 1-2 weeks.
[Clinical evidence of venous or lymphatic hypertension never reported, though an experimental model of chylothorax was created by ligation of the cranial vena cava in dogs (fossum am j vet res 1986)]

11. Idiopathic chylothorax
Failure to identify an underlying cause
Diagnosis of exclusion
Idiopathic chylothorax is a rule out diagnosis and results from the failure to identify a primary cause. As with most idiopathic diseases, we probably just haven’t recognized the underlying cause yet.

12. Other diagnostics CBC/Chem/UA Chest radiographs Heartworm antigen test
Echocardiography
Thoracic/abdominal CT
Lymphangiography
CBC often normal +/- lymphopenia, chem can show electrolyte abnormalities consistent with 3rd spacing (hyponatremia, hyperkalemia), hypoproteinemia particularly with more chronic effusions
Chest x-rays after tap- look for lung lobe torsion, cardiac silhouette, pulmonary changes, mediastinal masses, ect
Dirofilaria is reported cause of chylothorax
Echo- congenital or acquired heart conditions can result in chylothorax
CT to look for neoplasia or anything compressing
Lymphangiography we will talk more about but is important for identifying the lymphatic anatomy
Brisson, AJVR, 2006

13. Treatment options Medical Management Surgery Definitive
Salvage Procedures

14. Medical management Low fat diet TPN Medium chain triglycerides?
Steroids?
Thoracocentesis as needed
Low fat diet- goal to decrease lipids content in effusion not volume of effusion. Lower lipid content lends itself to better reabsorption. Staple treatment no matter what else is done for duration of effusion
TPN is used to bypass the GI tract and decrease lymph flow by reduction of fat absorption. Seems to work but is a short term option and does not address the problem
Feeding MC triglycerides: may be absorbed by portal vein directly, not lymphatics (disproven in 1993 paper – Sikkema- do enter into lymphatics). Not palatable
Steroids may help with the inflammatory component
Thoracocentesis is not benign. Risk of bleeding, infection, pneumo, ect

15. Medical management Rutin (Benzopyrone) 50-100 mg/kg TID, PO
Octreotide 10ug/kg TID, SQ days
Rutin- benzopyrone--The main function appears to be stimulation of macrophages, which promotes proteolysis within the lymph. Protein fragments can then be reabsorbed into the blood. Rutin is active orally and topically, and is relatively inexpensive, and free of side effects.
Octreotide: somatostatin analogue: The exact MOA is not known in chylothorax but it is postulated to work though decrease GI/biliary/pancreatic secretions and reduction of splanchnic blood flow resulting in decreased chylous production
For both rutin and octreotide the studies have been small and inconclusive. May help and neither appears to be harmful
(Sicard, Proceedings of the ACVS 2003
Proven to help with traumatic chylous leakage in 8 experimental dogs (Am Surg Dec;66(12): Octreotide in the treatment of thoracic duct injuries.
Markham KM, Glover JL, Welsh RJ, Lucas RJ, Bendick PJ.)

16. Medical management Good for traumatic chylothorax
2 weeks
When to go to surgery…
Large persistent volume
>4 weeks
No studies comparing medical vs. surgical management
Medical management is recommended for at least 2 weeks if chylothorax secondary to trauma is suspected because it is self limiting.
No good timeline for when to go to surgery. Large persistent volume >4 weeks. No studies comparing medical management to surgical management. Often animals not responsive to medical management will proceed to surgery.

17. Anatomy The path of the lymph fluid
Cisterna chyli is abdominal lymph reservoir
Thoracic duct (TD) arises from cisterna chyli
TD is major lymphatic vessel for return of lymph to venous system
TD anatomy varies, especially in idiopathic chylothorax cases
Dogs: right->left
Cats: left
The mesenteric lymphatics arborize into a large abdominal lymphatic reservoir (cisterna) at approx level of 1st lumbar vertebrae, medial to the left kidney. The hepatobiliary and intestinal lymph all feeds into the cysterna chyli.
From cisterna the cranial continuation of the path is the thoracic duct
Thoracic duct is the major conduit for lymph return to the venous system. It terminates in cranial thorax at the lymphaticovenous junction in the cranial vena cava near where the internal and external jugular veins meet
TD usually begins as a single duct but often has multiple branches and variable anatomy, particularly in idiopathic chylothorax cases
Dogs: the TD runs to right of midline in caudal thorax and crosses to left at approx 5th intercostal space
Cats: on left side throughout its course in the thorax

18. Cisterna chyli Brisson, AJVR, 2006
Contrast in the lyphatics highlighting the CC

19. Thoracic duct Brisson, AJVR, 2006
Contrast highlighting the thoracic duct. Note the relative tortuosity of the vessels cranially.

20. Cartoon: CC is medial to the hilus of the left kidney

21. Pre-operative planning
Lymphangiography
Intestinal (mesenteric)
Open, laparoscopic or
U/S guided
Popliteal
Rads vs. Fluoro vs. CT
CT shows more branches
Missed branches
Post-op confirmation
Athough not necessary, lymphangiography is very helpful. Lymphaniography is the injection of contrast medium into the lymphatics and using the aid of imaging to evaluate the anatomy.
This was traditionally done by direct catheterization of the mesenteric lymphatics via opening the abdomen or laparoscopically. In these cases, the best images are taken seconds later so a C arm comes in really handy. It has also been done with ultrasound guidance (though less relaibly due to obvious constraints with visualization).
Diagnostic studies can also be achieved with popliteal LN injection of dye, with contrast showing up in the TD on radiographs approximately 10 min later.
You can perform lymphangiography with plain radiographs (VD is most helpful view), in real time with fluoroscopy, or with CT. You may need to alter your technique of dye injection based on what imaging is available to you.
CT is used most commonly in people and it seems to show the most branches. You also don’t have to worry about superimposition and you get nice 3d reconstructions.
** concern with all these techniques that not all branches are equally opacified (some are missed)
Immediately post op lymphangiography is also recommended to confirm complete duct ligation or ablation with no remaining tibutaries. However even the value of this is called into question. one study showed that 2 cats that were dissected down to the TD but not actually occluded showed immediate post op lack of contrast cranial to the dissection site as if ligation had occurred. 4 weeks later the lymphangiography was repeated and the TD was patent. False lymphangiograms
Naganobu: -- popliteal injection 4 normal, 1 chylothorax; seen with 1ml/kg at 2ml/ml ; see contrast in approx 10 mins on rads
Johnson: CT 5 min after u/s guided mesenteric injection; successful in 6 patients
CT-- used in humans to ID integrity of the thoracic duct described in the 80’s and 90’s
Esterline: CT better at several spots, but not every slice on CT. greater contrast resolution
Naganobu, Vet Surg 2006
Johnson, Vet Surg 2009
Esterline, Vet Rad/US 2005

22. Lymphangiogram Sicard et al. Vet Surg 2005
Preoperative lymphangiograms illustrate the diversity of the thoracic duct in different patients
Sicard et al. Vet Surg 2005

23. Intraoperative identification
To identify the lymphatics during surgery
Feed high fat meal prior to surgery
Methylene blue
Heterocyclic aromatic compound
1% aqueous, 0.5mg/kg (up to 10mg) or 0.2mls diluted
Injected: lymph nodes (popliteal, inguinal, mesenteric), diaphragm, distal limb/paw pad, esophagus or via lymphatic catheterization
Complications: Heinz body anemia, increased ALP, renal failure
Preop planning is great, but you need some tricks for when you are in surgery and the lymphatics just aren’t jumping out at you.
Feeding a high fat meal like cream or vegetable oil 3-4 hours prior to surgery has also been reported to increase visibility of lymphatic vessels
One of the most common tools is methylene blue.
Methylene blue is a jack of all trades. Besides being a dye compound, other reported scientific properties include neuroprotective, cognitive, and memory enhancing qualities, a chemical redox indicator, a photosensitizer, RNA/DNA stain, cheap treatment for malaria (turns urine green and sclera blue), cancer treatment- selectively inducing apoptosis of cancer cells, has virusidal properties and been used in treatments for everything from HIV to Hepatitis C to west nile virus, to plaque psoriasis, also used to treat cyanide and carbon monoxide poisoning to name a few….

24. Methylene blue
This graph from this 2003 study compares methylene blue injected at the mesenteric LN or popliteal. No significant time delay, both sites reached maximum coloration of the TD at 10 minutes, though the popliteal injection site never achieved the same intensity of coloration. The investigators stopped the study at 60 minutes at which time dye was still present and highlighting the lymphatics. We don’t know how long it would stay, but 60 minutes was deemed sufficient time to identify and ligate the branches of the TD.
Enwiller, Vet Surg 2003

25. Methylene blue Sicard, Vet Surg, 2003
This photograph is the view of a right 11th intercostal thoracotomy. The thoracic duct is weakly visible.
This photograph is the same view following injection of methylene blue into the lymphatic system. You can see the usefulness and importance of the injection to allow complete visualization of the thoracic duct for adequate ligation.
Sicard, Vet Surg, 2003

26. Methylene blue
Picture of a methylene blue injection into a mesenteric lymph node and the thoracic duct lit up in blue
Enwiller, Vet Surg 2003

27. Surgical Options Thoracic duct ligation Pericardiectomy
Cisterna chyli ablation
Omentalization
Embolization
Shunts
Pleural Port
Pleurodesis
Pleural stripping
Anything with this many different options should tip you off that we don’t know the best one…
Multiple procedures- usually a combination performed- no one magic bullet

28. Thoracic Duct Ligation
Ligation of the thoracic duct is thought to allow the redirection of chyle away from the thoracic duct into new lymphaticovenous anastomoses in the abdomen. The abdomen is more equipped to handle reabsorption of chyle
Redirection of chyle away from the thoracic duct into new lymphaticovenous anastomoses
[Image modified from JAAHA, 18:769-77, 1982]

29. Thoracic Duct Ligation: Open
First reported in 1958
Goal: occlude duct at entry to thorax, encourage lymphaticovenous anastomoses in abdomen
Approach
9th-10th intercostal thoracotomy (L cat, right dogs)
Transdiaphragmatic in cats and small dogs
Want to ligate as far caudally as possible- few branches. Can ligate them individually or en block meaning everything dorsal to the aorta and ventral to the sympathetic trunk (even including azygous vein with no ill effects). Hard to get all the tiny branches, some can be adhered to the aorta. You can use hemoclips or nonabsorbable suture. Can also ablate with the use of ligasure to heat, denature, and seal the ducts.
MacDonald VS 2008
- cadaver study- 93% occluded with en bloc ligation (13/14 )
- may obviate need for lymphangiography
- performed in people- Bonavina 2001
- ok to ligate azygous
Controversy over efficacy of post-operative imaging ******
Yes: birchard jaaha 1982, javma 1998, no Kerpsack: recurrence in 5/18 cats even though post op confirmed occlusion of TD
Small branches may not fill
Success rate
50-60 % in dogs even w/lymphangiography pre & post ligation
20% to 40% in cats
Fossum TW. Feline Chylothorax. Compendium 1993; 15:
Goal: occlude duct at entry to thorax
Approach
9th-10th intercostal thoracotomy
Transdiaphragmatic
Dorsal to aorta, ventral to sympathetic trunk
Individual vs. en bloc
Ligation vs. ablation

30. Thoracic Duct Ligation
Incomplete ligation will result in failure but it is also thought that the failure can result from the formation of collateral lymphatics that bypass the ligature site.
Failure may occur due to incomplete ligation or formation of collateral lymphatics that bypass the ligature site instead of forming new lymphaticovenous drainage sites

31. Open ligation
Tobias, 2010

32. TDL: Thoracoscopic
Goal: TDL without morbidity of thoracotomy, improved visualization
Approach
Sternal (or lateral)
2 instrument ports to allow dissection dorsal to aorta
Evaluate contralateral hemithorax for branches
may be better able to access further caudally;
Can use clips, harmonic scalpel, ligasure
Mayhew JAVMA 2012; Allman, Radlinsky Vet Surg 2010; Sakals Vet Surg 2011; Radlinsky Vet Surg 2002; Leasure Vet Surg 2011

33. More technically challenging
More technically challenging? Similar success rates to the open procedures
Singh, 2012

34. Pericardiectomy Goal: decrease right sided venous pressure Approach
Intercostal, median sternotomy, transdiaphragmatic, thoracoscopic (paraxyphoid or intercostal)
Pericardial window or subtotal pericardiectomy
Excise pericardium ventral to phrenic nerves
Initially developed as a salvage procedure for animals with persistent chylous effusion following TDL but it is now commonly performed in conjunction with TDL to maximize likelihood of positive response. Not usually done solo
Chylothorax leads to thickened pericardium or thick tissue overlying the pericardium from the chronic irritation of chyle. this in turn may increase systemic venous pressure further, contributing to more fluid build up and these abnormal venous pressures may act to impede drainage of chyle into the cranial vena cava while increasing lymphatic flow through the TD.
The goal of the pericardiectomy may lower right-sided venous pressures. However, not all cases of elevated r sided p lead to chylothoraxs
(Take down the mediastinum
 Chronic effusions are irritating and cause pleural/pericardial thickening In original reports (for both open and thoracoscopic procedures) excellent outcome in some authors’ hands
Subsequent reports vary 57%-100%
fossum jvim 2004
Tdl + Pc
9d 10c, 100%d 80% c, incl one dog with just s/s eff post tdl 
theory- thickened peril by chyle-- right sided venous p
lymphangiography not successful in any cats!!
Carobbi vet rec 2008
13/14 dogs resolved following tdl/pc, 1 req re-op but then resolved
Para xiphoid approach is more complete than intercostal. Port in r/l paraxiphoid, then an intercostal space ventral to lungs
Fossum, JVIM 2004, Carobbi Vet Rec 2008, McAnulty VS 2011

35. Open pericardiectomy

36. Cisterna chyli ablation
Goal: reroute lymphatic drainage
Major abdominal vessels, mesenteric root, azygous
Avoid lymphatic hypertension
seen with TDL
Usually performed with TDL
Approach: ventral midline or paracostal incision
Mobilize kidney, excise tissue
Goal of rerouting or disrupting lymphatic drainage to form new lymphaticovenous junctions with major abominal vessels, mesenteric root, azygous vein and avoid lymphatic hypertension with TDL which may contribute to collateralization.
Approach: ventral midline or left paracostal incision, transdiaphragmatic and minimally invasive approaches possible.
Incise the peritoneum lateral to the left kidney, mobiilize and retract the kidney medially. Inject an ileocecal LN with methylene blue to help with identification, then sharply excise all visible membranes of the CC and associated lymphatic connections to the caudal TD.
Can leave the kidney mobile or tack it back inplace
Experimental study in 6 healthy beagles- led to direct intra-abdominal lymphaticovenous anastomoses– shunting to abdominal vasculature! (To azygous in 3 dogs w/o CCA)
Pics- shunt to azygous vs. directly to CVC , phrenicoabdominal, or mesenterics, 1 reconnected to CC  azygous
Staiger- combined right paracostal approach for TDL, CCA, and pericardectomy (6/6 w all 3 did well, 2/4 w/o peric recurred)
Hayashi- TDL r caudal intercostal, CCA left flank or midline (better)
Sakals: transabdominal vs transdiaphragmatic approaches (TD 100%, 71% TA); risk of aortic laceration!– ideally to be performed thru scope-TDL portals

37. Cisterna chyli ablation
Realistically this is nearly always done with TDL.
Hypertension caused by thoracic duct ligation alone can result in the development of collateral lymphatics and the redevelopment of chylothorax
The disruption of the cisterna chyli will relieve lymphatic hypertension and promote new routes of lymphatic drainage
Also proposed to omentalize the CCA site but this has not shown to change outcome.
Combining cisterna chyli ablation with thoracic duct ligation
[Image modified from JAAHA, 18:769-77, 1982]

38. This image is taken within the abdomen via a ventral midline celiotomy
This image is taken within the abdomen via a ventral midline celiotomy. The cisterna chyli, highlighted by the injection of MB, is seen just caudal to the left lateral lobe of the liver. The left kidney is being retracted medially.
The cisternal membranes are removed until the aorta is reached. The omentum is pulled into the area and tacked to the abdominal wall.
Sicard et al. Vet Surg 2005

39. This is an image with the abdominal cavity illustrating the arborization of the abdominal lymphatics several weeks following the procedure. Tough to tell in the picture but they are draining into vessels in the abdomen

40. 1 month post TDL with CCA Sicard et al. Vet Surg 2005 Caudal vena cava
In 3 of the dogs 1month after TDL and CCA they performed a lymphangiogram and saw diffuse arborizing lymphatics. They appeared to be direct lymphaticovenous anastomoses since the contrast rapidly dissipated with continued injection.
(In the remaining 3 dogs, direct shunting into a major vein was observed.
2 dogs had direct shunting into the caudal vena cava.
And in one dog there was shunting into the azygos vein.)
Azygos vein
Sicard et al. Vet Surg 2005

41. Omentalization Goal: provides absorptive surface? Angiogenesis
Drains back to TD
Angiogenesis
Source of immune cells
Diaphragmatic incision
Or- subcutaneous tunnel
Tack intrathoracically
Salvage vs Ancillary procedure
Omentum is a natural drain so exploited this function to remove chyle from thorax. May also help seal the leaking TD
However, the omentum drains lymph back into the TD, so in that sense it is kind of pointless
Also has angiogenic and immune properties
Pass it into chest through diaphragmatic incision of SQ tunnel and tack to the mediastinum. Avoid constricting, kinking or twisting it as you move it to the chest
Originally described as ‘salvage’ procedures in a dog and cat, where conventional surgery (i.e. TDL) could not be achieved because thickening prevented identification of the structures
Now considered an ancillary procedure when combined with TDL or TDL & pericardectomy.
(Interestingly TDL/P/O added no benefit over TDL/P alone. Bussadori et al
Williams Vet Surg 1999
LaFond Jaaha case report of a cat who failed TDL, had restrictive pleuritis, resolved with omentalization
Da Silva JAVMA dogs with omentalization were more likely to resolve (2/3 w/o oment recurred, 8/8 with resolved))

42. Omentalization
Omentum being pulled through the diaphragm into the thorax

43. Embolization
Cyanoacrylate glue injected into cannulated mesenteric lymphatic vessel
Occluded 100% of TD in healthy dogs, but 33% clinical efficacy
Risk of emboli in circulation, lungs
Salvage procedure?
Cyanoacrylate injected through a mesenteric lymphatic catheter to embolize CC and TD. Mix glue with contrast so it can be done under fluoro guidance with lymphangiography
Worked in 8/8 normal dogs (8) but only 2/6 33% idiopathc chylothorx (2/6) Described as a salvage procedure for those failing management due to its low clinical success rate but has potential as first line treatment. Need more studies. It is a technique commonly performed in humans.
Adv- direct visualization of TD not required
Disadv- incomplete filling of tributaries with glue, collateralization, risk of emboli in circulation and lungs
Presented at ACVS- Pardo 1995 (experiment Pardo 1989)
Inject at the level of T10-13
Performed in children with chylothorax successfully +/- endovascular microcoil to hold the glue
Pediatrics Jul;128(1):e doi: /peds Epub 2011 Jun 6.
Percutaneous thoracic duct embolization as a treatment for intrathoracic chyle leaks in infants.
Itkin M, Krishnamurthy G, Naim MY, Bird GL, Keller MS.
Madeline Miller – case from 2010
Treatment of choice for people with traumatic chylothorax
Experimental model in dogs (1989)
Case report (AMC, Penn & Tufts 2010)
Mesenteric injection of glue
Avoids thoracic surgery, embolizes cisterna too and may get TD branches
No significant complications
Photos courtesy of Weisse
Singh, Am J Vet Res 2011; Pardo ACVS 1995; Weisse JAVMA 2008

44. Percutaneous catherization & embolization
Percutaneous catheterization of cisterna as an even less invasive option
Punctured 9/15, catheterized 5/9
Advance wire into thoracic duct
Embolize with microcoils and either cyanoacrylate or ethylene vinyl alcohol
4/4 successful…. So 4/15. technically demanding
(Substantial increase in TD pressure
Theoretically could make effusion worse)
Singh et al. AJVR 2011

45. Shunts Salvage procedure Pleuroperitoneal- active
Pleuroperitoneal- passive
Pleurovenous shunt
Overall shunts have a high rate of complications (72%) , but high rate of owner satisfaction- Smeak
MST 27 months, DFI 20mo
Salvage procedure
Pleuroperitoneal- active
Denver catheter
Kinking, infection, dislodgement, obstruction, abdominal distension, seeding
Pleuroperitoneal- passive
Fenestrated silastic sheet
Obstruction
Pleurovenous shunt
Technical difficulty, thrombosis, migration
Smeak et al, JAVMA 2001
Willauer JAVMA 1987
Peterson Vet Surg 1996

46. Pleuroperitoneal active shunts
Described 14 dogs with chronic effusions – 10/14 had chylothorax. More successful with the nonchylous effusions
Afferent fenestrated side placed in thoracic cavity, efferent side place in peritoneal cavity
Denver pump with one way valve placed under external abdominal oblique over a rib. Pumped daily as needed to control clinical signs. Each pump is 1ml.
Was quite effective as a palliative measure but with adverse effects common in the short (e.g. Getting kinked, infection, owner compliance) and long term (e.g. Obstruction of shunt, pyothorax, abdominal distension).
No successful reports in cats
Cannot use if there is a generalized impairment to fluid resorption from the body (e.g. Right sided failure, diffuse lymphatic pathology).
Overall good respiratory outcome (e.g. Not short of breath) for a mean of 20 months, survival overall mean 27 months. (all effusions mixed)
Smeak et al. JAVMA 2001

47. Pleuroperitoneal passive shunts
Fenestrated silastic sheet placed in defect created in diaphragm or transdiaphragmatic tubes
Provides drainage into abdomen
Reabsorption via visceral and peritoneal lymphatics
Shunting drive by respiration
Longterm patency of drains discouraging
Fibrin clots, adhesions, omentum
Pleuroperitoneal- passive
Aided in movement by respiration
Fenestrated silastic sheet
Obstruction
Prosthetic mesh rapidly obstructed

48. Pleurovenous shunts
Pleurovenous shunt
Technical difficulty, thrombosis, migration
Denver catheter (inserted into veins vs other)
Efferent side placed in the azygous vein or caudal vena cava
Can be tunneled to ventral cervical region and inserted into jugular vein & down to cranial vena cava
Not really recommended in vet med.

49. PleuralPort Percutaneous (or open) Port function 1-391 days
Incision over 10th rib
Tunnel 2-3 spaces cranially
Or-- place 1st, then tunnel caudally
Port function days
Median 20 days
Complications
Kinking, migration, leakage, hemithorax access, obstruction, pocketing
Place as conjunctive therapy?
Percutaneous (or open)
Incision over 10th rib
Tunnel 2-3 spaces cranially
Retract incision dorsally, suture to SQ
Or-- place 1st, then tunnel caudally
Originally described as salvage or palliative procedure for intractable effusion but I would argue that these should be placed in surgery. Even if the definitive surgical procedure is successful, it takes an average of a couple weeks for the effusion to resolve. This provides a minimally invasive way to empty the chest cavity in the mean time. Nonsqueamish owners can fairly easily be trained to use this. Better option than chest tube which is too risky to send animal home with
Brooks et al- 6 dogs, 4 cats, 11 ports, 9 percutaneously
Obstruction in 3 cases
Port function days (median 20 days), in place for d.
Rec hep with 100iu/ml?
Brooks, Vet Surg 2011

50. Use Huber needles
+/- Hep Lock

51. Out-dated modalities…
Pleurodesis
Talc, blood, antibiotics, mechanical abrasions
Do not form adhesions in dogs
Pain
Decortication (pleural stripping)
Hemorrhage
Intractable pneumothorax
Pleurodesis is the attempt to obliterate the pleural space by stimulating adhesions to form between the visceral and parietal pleura. Effective in humans but not shown to work in dogs
(tetracylcine HCl, quinacrine HCL, bleomycin, fluorouracil, talc)
Fossum thoracoscopic pleurodesis- not adhesions
Decortication- attempts in patients with fibrosing pleuritis to peel off the scar tissue left behind

52. Success: By the numbers
Procedure
Success Rate
Rutin
67%* (cats)1
Octreotide
40%2
TDL
50-59% (dogs)
% (cats) 3
TDL + SP
60-100% (dogs)
80% (cats) 4
Thoracoscopic TDL + SP
% (dogs)5
TDL + CCA
% (dogs)6
TDL + SP + omentalization
72.7% (dogs) 7
57% (d+c) 8
MST 209d (c) 211d (d) 9
Embolization
33% 10
1.Total of 6 cats in 3 reports
Thompson JAVMA 1999
Gould Can Vet J 2004
Kopko Can Vet J 2005
2. Sicard Vet Surg 2003
3. Most studies in 1980s/1990s, various techniques: (Birchard JAVMA 1998; Harpster CVT 1986; Viehoff german 2003; Birchard JAAH 1982; Birchard JAVMA 1998; Fossum JAVMA 1999; Kerpsack JAVMA 1994)
4. Dr Fossum has reported excellent success with this and subsequent studies slightly less so. Surgeon experience? (Fossum JVIM 2004; Carobbi Vet Rec 2008; McAnulty Vet Surg 2011)
5. Less invasive option, similar outcomes to open technique: (Allman VS 2010; Mayhew 2012)
6. Staiger VS 2011
Hayashi VS 2005
McAnulty Vet Surg 2011
7. Da Silva JAVMA 2011
8. Bussadori Vet J 2010
9. Stewart JAAHA 2010
10. Need more studies: Pardo et al Proc ACVS 1995
Variability in time to resolution of effusion 1-50 days noted
HOWEVER: McAnulty et al VS 2011: 60% with TDL-SP, 83% with CCA-TDL (not stat sign)
- Salvage procedures are recommended
Also, non-chylous effusion
Recurrence can be seen as long as 5 years post op
Adapted from Singh. Compendium 2012

53. Progression and sequelae
Fibrosing pleuritis
Inflammatory changes to mesothelial cells
Increase type III collagen
Decreased fibrinolysis
Restrictive pleuritis
Failure to expand lungs despite thoracocentesis
Pericarditis
Malnutrition, dehydration, loss of lipids, protein, fat-soluble vitamins, lymphocyte depletion
Fibrosing pleuritis can develop with any effusions thought to cause chronic inflammation. High fibrin formation-> mesothelial desquamation, increased permeability, increase type III collagen resulting in promoted fibrosis. Chronic pleural effusion may lead to impairment of fibrin degradation and dilution local plasminogen activator (for fibrinolysis).
Restrictive pleuritis is a manifestation where Pleura is thickened by diffuse fibrous tissue that restricts normal pulmonary expansion. Can be misdiagnosed by having a large amount of pleural effusion (rounding of lobes). If you can’t get a lot of fluid out, be suspicious of atelectasis and fibrosis of the lungs secondary to this condition. Caution because you can very easily give them a pneumo trying to tap the effusion. CT may be better than x-rays because it is hard to differentiate persistent effusion vs fibrosis
Other sequelae include pericarditis and malnutrition….

54. Fibrosing pleuritis
disgusting

55. Take-home points Idiopathic is most common
Diagnosis based on appearance, cytology, triglycerides
Medical management frequently fails
No ONE surgical technique to recommend
TDL, CCA, pericardectomy and pleuralport?
More minimally invasive techniques emerging
Post-operative lymphagiograms may or may not be helpful
High morbidity with long term effusion

56. References
Allman DA, Radlinsky MG, Ralph AG, et al: Thoracoscopic thoracic duct ligation and thoracoscopic pericardiectomy for treatment of chylothorax in dogs. Vet Surg 39:21, 2010.
Brooks A. et. al. Vet Surg Use of the PleuralPort device for management of pleural effusion in six dogs and four cats.
Bussadori et al. Pleural omentalisation with en bloc ligation of the TD and PC for IC in 9 dogs and 4 cats. Vet J 188: , 2011
Carobbi B, White RAS, Romanelli G: Treatment of idiopathic chylothorax in 14 dogs by ligation of the thoracic duct and partial pericardectomy. Vet Rec 163:743, 2008
Chun H, Cho H, Cheon H, et al: Determination of optimal dosage and delay time for computed tomographic lymphangiography after percutaneous injection of iohexol into popliteal lymph nodes in dogs. J Vet Med Sci 71:873, 2009.
DaSilva CA, Monnet E. Long term outcome of dogs treated surgically for idiopathic chylothorax:11 cases ( ). JAVMA 239: ,2011
Enwiller TM, Radlinsky MG, Mason DE, et al: Popliteal and mesenteric lymph node injection with methylene blue for coloration of the thoracic duct in dogs. Vet Surg 32:359, 2003.
Esterline ML et al: Comparison of radiographic and CT lymphangiography for identification of the canine thoracic duct. Vet Radiol Ultrasound 2005;46:
Fossum TW. Chylothorax in cats: is there a role for surgery? J Fel Med Surg 3:73-79, 2001
Fossum TW, Mertens MM, Miller MW, et al: Thoracic duct ligation and pericardectomy for treatment of idiopathic chylothorax. J Vet Intern Med 18:307, 2004.
Hayashi K, Sicard G, Gellasch K, et al: Cisterna chyli ablation with thoracic duct ligation for chylothorax: results in eight dogs. Vet Surg 34:519, 2005.
Hinrichs et al. Lymphangiosarcomas in cats: a retrospective study of 12 cases. Vet Path 36: , 1999
Johnson EG et al. Computed tomographic lymphography of the thoracic duct by mesenteric lymph node injection. Vet Surg 38: ,2009.
Itkin M et al. Percutaneous thoracic duct embolization as a treatment for intrathoracic chyle leaks in infants. Pediatrics 2011 Jul;128(1):e237-41
Kerpsack et al. Evaluation of mesenteric lymphangiography and TDL in cats with chylothorax: 19 cases ( ). JAVMA 205(5):711-5, 1994
Kovak JR, Ludwig LL, Bergman PJ, et al: Use of thoracoscopy to determine the etiology of pleural effusion in dogs and cats: 18 cases (1998–2001). J Am Vet Med Assoc 221:990, 2002
LaFond E, Weirich WE, Salisbury SK: Omentalization of the thorax for treatment of idiopathic chylothorax with constrictive pleuritis in a cat. J Am Anim Hosp Assoc 38:74, 2002.
McAnulty JF. Prospective comparison of cisterna chyli ablation to pericardectomy for treatment of spontaneously occurring idiopathic chylothorax in the dog. Vet Surg 40: , 2011.
Naganobu et al: Lymphgraphy of the thoracic duct by the percutaneous injection of iohexol into the popliteal lyph node of dogs: experimental study and clinical application. Veterinary Surgery 35: , 2006.
Pardo AD, et al. Transcatheter thoracicduct embolization in the dog. An experimental study. Vet Surg1989;18:279–285.
Peterson SL. Postcaval thrombosis and delayed shun migration after pleuroperitoneal venous shunting. Vet Surg 25: , 1996.
Radlinsky MG, Mason DE, Biller DS, et al: Thoracoscopic visualization and ligation of the thoracic duct in dogs. Vet Surg 31:138, 2002.
Sicard GK et al: The use of a somatostatin analogue for the treatment of idiopathic chylothorax in dogs and cats. Proceedings ACVS 2003.
Sikkema DA, McLoughlin MA, Birhcard SJ. Effect of dietary fat on triglyceride and fatty acid composition of thoracic duct lymph in dogs. Vet Surg 1993;22:
Smeak DD, Birchard SJ, McLoughlin MA, et al: Treatment of chronic pleural effusion with pleuroperitoneal shunts in dogs: 14 cases (1985–1999). J Am Vet Med Assoc 219:1590, 2001.
Staiger et al: single paracostal approach to thoracic duct and cisterna chyli: experimental study and case series. Vet Surg 40: , 2011
Weisse et al: Potential applications of interventional radiology in veterinary medicine. JAVMA 233:1564, 2008