Canine and Feline Exudative Pleural Diseases - Epstein 2020

Question 1

Do right and left pleural
cavities communicate in dogs and cats?

Answer 1

Controversial: anatomists say mediastinum is complete in the dog, whereas clinical experience
suggests this might not be accurate.
Some dogs and cats
have a communication between L and R pleural space, whereas in other
animals it does not communicate, or that communications can be sealed because
of disease.

Question 2

What’s the normal amount of fluid in the pleural space in dogs and cats?

Answer 2

Dogs 0.1ml/kg
Cats 0.3m/kg

Question 3

What define a hemothorax?

Answer 3

no standardie definition. hematocrit.
Effusion HCT at least 25%
of peripheral blood.

Question 4

How do you differentiate iatrogenic hemorrhage caused by thoracocentesis from actual hemothorax?

Answer 4

Iatrogenic hemorrhage = presence of platelets in
the fluid and the lack of erythrophagocytosis.

Question 5

What are possible causes of hemothorax?

Answer 5

Trauma, coagulopathies,
neoplasia (hemangiosarc, mesothelioma, metastatic carc, osteosarc, pulmonary carc) lung lobe torsion, pancreatitis, infectious (Streptococcus equi subspecies
zooepidemicus, Angiostrongylus vasorum, Spirocerca lupi, Dirofilaria immitis)

Question 6

What are the breeds most commonly presenting with lung lobe torsion?

Answer 6

Afghan hounds and pugs

Question 7

How do you confirm bilothorax?

Answer 7

Detection of a pleural fluid-to-serum bilirubin ratio greater than 1:1

Question 8

What are common causes of pyothorax in dogs and cats?

Answer 8

Dogs: migrating foreign material, penetrating bite
wounds, hematogenous spread, esophageal perforation, parasitic migration, previous
thoracocentesis or thoracic surgery, progression of discospondylitis, and thoracic
neoplasia with abscessation.
Cats: parapneumonic spread, foreign body
migration, hematogenous spread, or penetrating thoracic wounds

Question 9

What are the most common pathogens isolated in dogs and cats with pyothorax?

Answer 9

Cats: Pasteurella spp
Dogs: Pasteurella
spp, Enterobacteriaceae, anaerobes, and Actinomyces/Nocardia spp,

Question 10

What’s the best CXR view to detect small amount of pleural effusion?

Answer 10

VD

Question 11

How commonly do cats with pyothorax present with fever?

Answer 11

50%

Question 12

What would prompt a surgical approach for pyotorax over medical management?

Answer 12

• pulmonary abscessation
• migrating foreign material
• failure to respond to medical therapy (persistence of effusion despite thoracostomy drainage, persistence of infectious organisms
  despite appropriate antimicrobial tx and thoracostomy drainage, or failure of clinical improvement in the first 72 hours).
• presence of Actinomyces (as associated with migrating grass awns)

Question 13

How is pleural lavage as part pf medical management of pyothorax performed?

Answer 13

warmed sterile isotonic saline is used at a dose of 10 to 20 mL/kg and is infused slowly into the thoracostomy tube and left in the pleural space
for 10 to 15 minutes before withdrawal. Typically, less fluid is removed than is infused.

Question 14

What is a possible complication of pleural lavage?

Answer 14

hypokalemia

Question 15

When is it advised to remove a chest tube?

Answer 15

when fluid production has
decreased to 3 to 5 mL/kg/d and improvement is noted clinically, radiographically,
and clinicopathologically.

Question 16

How long does medical management take according to literature?

Answer 16

5-8 days with chest tubes

Question 17

What is the recommended duration of antimicrobial therapy for medically managed pyothorax?

Answer 17

The International Society for Companion Animal Infectious Diseases
currently recommends treatment for a min of 3 weeks and ideally 4 to 6 weeks.

Question 18

Have you ever done bronchoscopy on pyothorax cases?

Answer 18

Bronchoscopy has been shown to be successful in
removal of foreign bodies in up to 76% of animals; therefore, bronchoscopy
should be considered before exploratory thoracotomy when a migrating grass awn
is the suspected cause of pyothorax.

Question 19

What’s the prognosis for pyothorax?

Answer 19

overall survival
of 83% in dogs and 62% in cats

Question 20

What is the primary lymphatic vessel within the thorax, and how does it function in the return of chyle to the venous system?

Answer 20

• thoracic duct,
  which is the cranial continuation of the cisterna chyli, which returns chyle from the intestines, liver, and caudal half of the body. The thoracic duct typically converges with the venous system at the point where the internal and external jugular veins meet the cranial vena cava.

Question 21

Causes of chylothorax

Answer 21

abnormalities of the lymphatic vessels (fungal granulomas, congenital abnormalities of the thoracic duct, or transmural
leakage across an intact but dilated vessel (lymphangiectasia)), increased venous
hydrostatic pressure at the level of the R heart (cardiac disease, cranial vena cava
obstruction, pericardial effusion, heartworm disease, congenital cardiac abnormalities
(tetralogy of Fallot, tricuspid dysplasia, double R ventricular outflow tract, or cor triatriatum
dexter), portal venous hypoplasia), abnormal organ positioning ( peritoneal-pericardial diaphragmatic hernia or lung lobe torsion),
neoplasia (thymoma, lymphoma), idiopathic, trauma to the thoracic duct.
Most common: idiopathic

Question 22

What do you see on cytology of chylothorax?

Answer 22

lymphocytes are the
predominant cell. With chronicity, nondegenerate neutrophils
tends to increase.
Small numbers of macrophages may also be noted.
A Sudan stain
can be used to verify lipid content in the sample.

Remember fluid might not appear milky if pt is anorexic

Question 23

How do you get definitive diagnosis of chylothorax?

Answer 23

detection of a triglyceride level in fluid that is higher than serum with paired
sample analysis

Question 24

What medical tx has been reported for chylothorax?

Answer 24

Rutin= nutraceutical purported to increase
uptake of edema fluid by lymphatic vessels. Showed some improvement in cats. Efficacy not reported for dogs.
- Octreotide= somatostatin
analogue that has been used in dogs and cats for management of chylothorax;
however, given its low success rate, expense, and parental route of delivery,
it is not widely used.

Question 25

When is surgical tx recommended for chylothorax?

Answer 25

If chylothorax persists
longer than 4 weeks despite medical therapy

Question 26

What surgical procedures are recommended for chylothorax?

Answer 26

thoracic duct ligation (TDL), cisterna chyli
ablation, and pericardiectomy