39 General Evaluation of the Equine Lower Respiratory Tract

RIGHT: cranial, middle (intermediate), caudal, and accessory

LEFT: cranial and caudal

What are the right and left lung lobes in horses?

Bronchoalveolar lavage fluid

Which is more specific for inflammation in the LOWER airway, for noninfectious disease, *tracheal lavage fluid or bronchoalveolar lavage fluid*?

Lack deep interlobar fissures

What do horses lack that make it hard to distinguish lung lobes?

5-6th ICS

Where does the trachea branch into right and left main stream bronchi in horses?

Right

Which bronchi is more straight in horses, *right or left*?

Primary bronchi (R and L) --> Lobar bronchi (secondary) --> segmental bronchi (tertiary) --> subsegmental

Name the parts of the bronchial tree in horses:

Pulmonary and bronchial circulation

What are the 2 vascular supplies of the horse lung?

Pulmonary circulation

Which vascular supply of the horse lungs is low pressure, low resistance, doing gas exchange and nutritents

Bronchial circulation

Which vascular supply of the horse lungs does nutrient supply to lymphatics, vascular and the airway components

Physical exam of respiratory system

Inspection, palpation, percussion (knocking on the sinuses), and auscultation are all part of the what in an equine exam?

Use a rebreathing bag

How can you get the horse to take deeper breaths so you can auscultate the lung sounds more clearly + observe recovery in a lung exam?

Dyspnea

This is defined as difficulty breathing

Tachypnea

This is rapid, shallow breathing

Eupnea

This is normal respiration

Hyperpnea

This is increased frequency and depth of breathing

Apnea

This means there is no discernable breathing

Hemoptysis

What is the term for coughing up blood

Dorsal displacement of the soft palate

What is this?

Pharynx, larynx, nasal passages

Name the parts of the upper respiratory tract in horses

Trachea, bronchi and bifurcation

Name the parts of the lower respiratory tract in horses

0 = none (left image)

5 = extreme ie. long streams covering the entire length of the trachea (right image)

You can score mucous in the trachea. What is the scale?

0 = none (left image)

4 = significant pooling (right image)

You can score blood in the trachea. What is the scale?

Exercise induced pulmonary hemorrhage

What typically causes blood to pool in the trachea in horses?

30-120 minutes post exercise (not right away)

When should you scope a horse after exercise if you are expecting blood to pool in the trachea?

1 = normal = paperthin

5 = thick

You can score the septum of the bronchi (aka the bronchial bifurcations). What is the scale?

ONLY LATERALS

What pulmonary radiographic view is the ONLY possible one in the adult horse?

4

How many shots of x-rays are required to cover the entire lung field in horses?

Thoracoscopy

What is the imaging technique of "endoscopy between the ribs" in horses?

Tracheal wash

note: while tracheal wash may do some inflammatory indication, you need to keep in mind it is NOT SPECIFIC as bronchoalveolar lavage fluid

What mechanism of respiratory sample collection in horses is best for infectious lower airway diseases like rhodococcus or aspiration pneumonia?

Lower airway = more specific

If you see inflammation with a BAL, where is the inflammation localized?

LOWER

Tracheal wash respiratory sample collection is used for *upper or lower* airway tract?

a. fast

d. equipment is costly

e. contamination of upper resp. into lower resp. tract is common

Both trans-tracheal and trans-endoscopic are examples of tracheal washes performed in horses. Select which of the following are true for TRANS-ENDOSCOPIC:

a. fast

b. must clip and need small incision

c. bad vizualization

d. equipment is costly

e. contamination of upper resp. into lower resp. tract is common

a. need sterile prep

b. must clip and need small incision

e. no contamination

Both trans-tracheal and trans-endoscopic are examples of tracheal washes performed in horses. Select which of the following are true for TRANS-TRACHEAL:

a. need sterile prep

b. must clip and need small incision

c. great vizualization

d. equipment is costly

e. no contamination

Trans tracheal

This is *trans tracheal* or *trans endoscopic* tracheal wash

Purple top EDTA

What collection tube do you use for collecting cytology of tracheal washes?

Endoscopy

What is this mechanism of broncho-alveolar lavage?

BAL tube

What is this mechanism of broncho-alveolar lavage, where the horse's head has to be extended (should use lidocaine to dec. coughing)?

endoscope

Which mechanism of broncho-alveolar lavage has better vizualization, but has higher cost and maintenance?

*endoscope or BAL tube*

BAL tube

Which mechanism of broncho-alveolar lavage has NO vizualization, but has lower cost and maintenance?

*endoscope or BAL tube*

Surfactant, Mucus, hemorrhage

What components of broncho-alveolar lavage fluid should you be assessing/looking for when processing a wash?

HEALTHY: 1/2 macrophages, 1/2 lymphocytes, less than 5% neutrophils

INFLAMMATORY: eosinophils, mast cells, erythrophages/hemosiderophages

What are the healthy versus inflammatory cells you will see in a horse on broncho alveolar lavage fluid

You have to take multiple, separate samples of the fluid as it is drained

It is very important you collect different "fractions of fluids" as you are doing a thoracocentesis. What does that mean?

Transthoracic (rare), transbronchial (thru endoscope)

What are the two techniques for performing pulmonary biopsy?

Pulmonary biopsy

What respiratory sample method would you do in horses ONLY in combination with other techniques, typically for diffuse lung disease?

d. diffuse lung disease

NOTE: it is important to know this is the ONLY indication, and that all others listed were CONTRAINDICATIONS

Select the INDICATION(S) for pulmonary biopsy:

a. hemoptysis

b. hemorrhage

c. pneumothorax

d. diffuse lung disease

e. infection

f. horses with respiratory distress

Arterial blood gas (done at very lowest part of neck)

What is this for pulmonary function testing?

Heparinized syringe

What type of syringe do you need specifically to collect an arterial blood gas sample?

More for upper resp. disease or poor performance

You do exercise testing in horses using a dynamic respiratory endoscope. Why do you do this?

a. tracheal lavage fluid

note: this is because tracheal lavage fluid is nonspecific. something as simple as being recently trailered with hay may cause inflammation. however, bronchoalveolar lavage fluid is not cultured because these are for noninfectious disease and more specific for lower airway inflammation

Which respiratory sample should you submit for culture:

a. tracheal lavage fluid

b. bronchoalveolar lavage fluid

TRUE = 30-120 mins

TRUE OR FALSE: it is best to perform endoscopy at a specific interval after exercising to determine if there is overt bleeding

FALSE = because it is not specific

TRUE OR FALSE: tracheal lavage fluid cytology is a good indicator for lower airway inflammation