Equine Respiratory

Question 1

Briefly describe the pathogenesis of bacterial pneumoniae within horses:

Answer 1

• Generally follows a viral infection - damaged respiratory epithelial cells → decreased mucociliary clearance → impaired immune function

Question 2

Does pleuropneumonia normally occur by itself?

Answer 2

• Conjunction with pneumoniae → significant accumulation of fluid + fibrin in the abdominal cavity

Question 3

What occurs to the pleural cavity in cases of pleuropneumonia?

Answer 3

• Significant accumulation of fluid and fibrin

Question 4

For bacterial pneumoniae and pleuropneumonia:

1. Provide an example of a gram positive bacteria
2. Provide an example of a gram negative bacteria
3. Provide an example of an anaerobic bacteria

Answer 4

1. Streptococcus zooepidemicus
2. E. coli, Pasteurella, Klebsiella
3. Bacteroides fragilis, Clostridium sp.

Question 5

What is an example of a viral cause of equine pneumoniae?

Answer 5

• Equine Herpes Virus
• Equine Influenza
• Equine Viral Arteritis Virus

Question 6

What is an example of a fungal cause of equine pneumoniae?

Answer 6

• Coccidiodes
• Cryptococcus
• Histoplasma
• Aspergillus

Question 7

What are three potential clfinicopathologic abnormalities seen with equine pneumoniae?

Answer 7

1. Leukopenia (acute) to leukocytosis (chronic)
2. Hyperfibrinogenemia
3. Hyperglobulinemia
4. Hypoproteinemia/Hypoalbuminaemia
5. Anemia

Question 8

What to the findings shown below indicate about the nature of the respiratory disease?

Answer 8

• severe weight loss,
• pectoral edema,
• ventral edema
• preputial edema

→ Indicates pleuropneumoniae

Question 9

What are four potential options for further diagnostics in cases of equine pleuropneumonia?

Answer 9

1. Thoracic ultrasonography
2. Transtracheal wash (TTW) w/bacterial culture
3. Collection of pleural fluid
4. CBC, Biochem, Arterial blood gas analysis

Question 10

What finding in the radiograph below indicates lung disease in the horse?

Answer 10

• Radiopacity in the caudal part of the lungs
• Severe interstitial → alveolar lung patterns

Question 11

Describe how the ultrasound of the lung below indicates pleuropneumonia:

Answer 11

• Free fluid in chest cavity
• Deposition of fibrin on thoracic wall + lung surface

Question 12

What is the long-term prognosis for pleuropneumonia in horses?

Answer 12

• Guarded to fair prognosis

Question 13

What may be an option for long-term treatment of pleuropneumonia?

Answer 13

Thoracocentesis/indwelling tube

Question 14

What is a potential long-term orthopaedic complication from pneumoniae in horses?

Answer 14

• Laminitis as a result of endotoxaemia

Question 15

Briefly describe the pathogenesis of recurrent airway obstruction in horses:

Answer 15

• Exposure to antigens → bronchoconstriction of airways + accumulation of neutrophils → compromised oxygen exchange

Question 16

A horse presents to you with respiratory signs. It is winter so the horse has been stalled in a barn and has been fed hay. What is the top differential?

Answer 16

• Recurrent airway obstruction - highly likely that the horse has developed an allergy to the hay

Question 17

Describe how respiratory effort is characterised in cases of RAO:

Answer 17

• Exaggerated end respiratory effort

Question 18

Describe what would be seen on BAL cytology for RAO:

Answer 18

• Increased number of neutrophils + Curshmann’s spiral (inspissated puss)
• * note BAL cytology in a normal horse should be mainly macrophages

Question 19

Describe how you would treat recurrent airway obstruction within a horse:

Answer 19

1. Change environment - wet feed/change the feed that is given
2. Medications: corticosteroids - Dexamethasone and prednisolone → decrease inflammation + bronchodilators (clenbuterol and albuterol) → helps with bronchoconstriction