41 Diseases and Disorders of the Equine Thorax

Penetrating wound

Shock, respiratory distress (nostril flaring, short quick breaths), hypoventilation (cyanotic membranes), weakness, and pain are all clinical signs for what thoracic problem?

To determine the extent of injury

What is the goal of diagnostic testing for penetrating thoracic wounds?

Radiographs: best for air

Ultrasound: best for fluid

What is the difference for evaluating penetrating thoracic wounds with radiographs versus ultrasound? Which is best for air? Fluid?

Thoracic auscultation

What is the best thing to do on your physical exam for thoracic trauma penetrating wound?

pH under 7.35, decrease HCO3 driver

What happens to pH, PaCO2, and HCO3 with metabolic acidosis?

pH over 7.45, increased HCO3 driver

What happens to pH, PaCO2, and HCO3 with metabolic alkalosis?

pH under 7.35, increased PCO2 driver

What happens to pH, PaCO2, and HCO3 with respiratory acidosis?

Over 7.45, decreased PCO2 driver

What happens to pH, PaCO2, and HCO3 with respiratory alkalosis?

b. lactic acidosis

d. diarrhea

f. renal failure

Select the things that commonly cause metabolic acidosis:

a. proximal GI obstruction

b. lactic acidosis

c. vomiting

d. diarrhea

e. hyperventilation

f. renal failure

a. proximal GI obstruction

c. vomiting

Select the things that commonly cause metabolic alkalosis:

a. proximal GI obstruction

b. lactic acidosis

c. vomiting

d. diarrhea

e. hyperventilation

f. renal failure

b. hypoventilation

note: like from collapsed lung

Select the things that commonly cause respiratory acidosis:

a. proximal GI obstruction

b. hypoventilation

c. vomiting

d. diarrhea

e. hyperventilation

f. renal failure

e. hyperventilation

note: like from pain

Select the things that commonly cause respiratory alkalosis:

a. proximal GI obstruction

b. hypoventilation

c. vomiting

d. diarrhea

e. hyperventilation

f. renal failure

Respiratory acidosis

A horse has the following blood gas:

pH 7.2

PCO2 65 mmHg

PaO2 40 mmHg

HCO3 25

BE -1

What is it?

CO2: 35-45 mmHg

HCO3: 22-26 mEq/L

What are the normal values for CO2 and HCO3

Do NOT pull the object out until you are ready to treat the pneumothorax, and when you DO pull it out = IMMEDIATELY pack to dec. air in chest

What is important to remember about penetrating wounds and what is causing it?

Ioban dressing

What is one of the best things used for wound dressing when addressing penetrating wounds in horses?

d. Metronidazole

Which of the following systemic antibiotics used in penetrating wound control is used for its ability to attack anaerobic bacteria?

a. penicillin

b. Naxcel

c. Gentamicin

d. Metronidazole

Jackson Pratt Drain

What is the closed suction drain used to treat penetrating wounds in horses?

DORSAL = removes air

VENTRAL = removes fluid

Why would you place a chest tube dorsally versus ventrally?

Heimlich valve

What is the name of the one way valve used to treat/drain penetrating wound trauma?

Jackson Pratt closed suction drain

What does the purple arrow indicate?

Dorsal chest tube for removing air

What does the light green/yellow arrow indicate?

Ventral chest tube for removing fluid

What does the teal blue color arrow indicate?

Heimlich one way valve

What does the large pink arrow indicate?

Penetrating chest wound into lung = guarded if septic pleuritis (50% die)

What is the prognosis like for an animal with a penetrating chest wound like this?

Because this commonly occurs from dystocia

Rib fractures are more common in foals than older horses. Why?

Rib fracture

What is happening here? Where the animal groans on palpation, has reluctance to move, and pain leading to "colic"?

Rib fractures

You see this problem BEST on ultrasound (ie. better than radiographs)

Surgical repair for displaced fractures near the heart, multiple fractures, or internal injuries

Besides pain control and restricted exercise, how can you manage rib fractures, particularly in foals?

Side B

note: if this were positive, this would be tension pneumothorax

Which one of these show the pneumothorax?

Pneumothorax

What is this horse at risk of?

Pneumothorax

This is caused by air infiltrating through tissues to the thorax from outside structures in horses, or overall just disruption of the thoracic cavity

Pneumothorax = increased detail in dorsal lung field

A horse presents with increased respiratory effort, tachypnea, cyanotic mucous membranes, and distress. You see this on radiographs.

Pneumothorax

You can treat this problem by removing the excess air to allow the lungs to reinflate and with supplemental O2?

Re-expansion pulmonary edema

What do you have to be aware of when removing excess air to allow the lungs to reinflate when treating a pneumothorax?

DORSAL

When you treat pneumothorax with a teat cannula and a suction pump and indwelling chest tube with Heimlich valve, where should you do this, *dorsally or ventrally*

It is a good medium for microbes to grow

What additional issues does hemothorax cause?

Hemothorax = question mark is fluid NOT air

A horse presents with increased respiratory effort, pale mucous membranes, stiff movement, and hypovolemic shock. You see this on ultrasound. Thoughts?

Ultrasound

What is the best diagnostic for hemothorax?

10%

What is the max % of bodyweight you can take from the donor when treating hemothorax via blood transfusion in a horse?

Axillary wounds

Wounds WHERE most commonly cause subcutaneous emphysema in horses?

Subcutaneous emphysema

What is happening in this horse that has a wound where air is sucked in but cannot leave?

Pneumomediastinum or pneumothorax

THIS PICTURE = pneumomediastinum

What is subcutaneous emphysema a sequelae to?

Excellent, air resorbs in 24-48 hours

What is prognosis like for subcutaneous emphysema in horses?

Diaphragmatic hernia

What is this?

Thoracoscopy, thoracotomy and rib resection, and lung biopsy

What surgical procedures are typically done in the thorax in horses?

Thoracoscopy

Which surgical procedure of the thorax do you do in horses to: explore wounds, hernias, or neoplasia, place a drain, go guided pulmonary biopsy, and window pericardectomy?

Thoracoscopy

With this procedure, you make a portal between the ribs and purposefully create a unilateral pneumothorax because a collapsed lung allows for easy exploration (remove air when done)

Refractory pleuropneumonia ie. inspissated pus that isn't getting better

May also do lung abscess, chronic pleural effusion

What is the main indication you would use rib resection and thoracotomy for?

Rib resection and thoracotomy

What is this?

Rib resection and thoracotomy

For this procedure, you remove 20-25 cm piece of at least one rib, elevate the periosteum, and use OB wire to cut the bone, then suture it open

Lung biopsy

What procedure would you do for neoplasia and granuloma masses in the lungs in horses?

You need to seal the lung to prevent closed pneumothorax (like with ligature or staplers)

What do you need to remember about the lung with lung biopsy?