Diseases of the Respiratory System (p461-637)

Question 1

What are the 5 primary means by which hypoxemia develops?

Answer 1

1) V/Q mismatch
2) Hypoventilation
3) Low partial pressure in inspired air
4) Diffusion limitation
5) Right to left shunting, intrapulmonary or intracardiac

Question 2

Match the percentages of cell distribution in a normal horse BAL. 50-70%; 30-50%; < 5 %; < 3 %; <0.1%

A) Eosinophils
B) Lymphocytes
C) Macrophages
D) Mast cells
E) Neutrophils

Answer 2

50-70% C) Macrophages
30-50% B) Lymphocytes
< 5% E) Neutrophils
< 3% D) Mast cells
< 0.1% A) Eosinophils

Question 3

What is the most common pathogen isolated in bronchopneumonia?

A) Pseudomonas
B) Bordetella
C) Rhodococcus
D) S. equi subsp zooepidemicus

Answer 3

D) S. equi subsp zooepidemicus

Question 4

What are some factors that significantly increase bacterial contamination of the lower respiratory tract in horses?

Answer 4

Head elevated, transportation and high-intensity exercises

Question 5

List two viruses that can decrease the mucocilliary clearance in horses, up to 30 days after infection.

Answer 5

Influenza

EHV-4

Question 6

At a cellular level, how does high-intensity exercise in horses lead to decreased bacterial clearance from the lungs?

Answer 6

High-intensity exercise leads to a decrease in blood neutrophil and bronchoalveolar macrophage phagocytic activity.

Question 7

Is this the first, second or third stage of pleuropneumonia? Exudative stage - pouring of sterile fluid into pleural space due to inflammation of the pleura; there is an increased permeability of the visceral capillaries

A) Stage 1
B) Stage 2
C) Stage 3

Answer 7

A) Stage 1 - if antimicrobial therapy is initiated at this time, pleural effusion may not become septic

Question 8

Is this the first, second or third stage of bacterial pleuropneumonia?

Fibropurulent stage - bacteria invade the pleural effusion from the pneumonia process and as the stage progresses fibrin is deposited in a continuous sheet

A) Stage 1
B) Stage 2
C) Stage 3

Answer 8

B) Stage 2 - degenerate neutrophils, bacteria and cellular debris accumulate in the pleural fluid; the fibrin sheet forms and there can be loculations and formation of limiting membranes, making drainage difficult

Question 9

Is this the first, second or third stage of bacterial pleuropneumonia?Organizational stage - an inelastic pleural peel is formed,that can render lung functionless

A) Stage 1
B) Stage 2
C) Stage 3

Answer 9

C) Stage 3 - this stage of bacterial pleuropneumonia occurs when fibroblasts grow into the exudate from both the visceral and parietal pleura surfaces

Question 10

What is the association between NCC count or protein concentration in pleural fluid and survival?

Answer 10

NONE

Question 11

A pleural fluid pH of less than A) ____ and glucose concentration less than B)___ are suggestive of septic effusion in horses.

Answer 11

A) 7.1B) 40 mg/dL

Question 12

Why should enrofloxacin never be used as a stand-alone therapy in horses with bronchopneumonia?

Answer 12

Enrofloxacin has a lack in activity against anaerobes and variable activity against streptococci.

Question 13

List additional treatments for a horse with bronchopneumonia, other than systemic antimicrobial therapy.

Answer 13

Aerosolized antimicrobials 
NSAIDs
Pleural drainage
Pleural lavage
Fibrinolytics
Thoracoscopy
Thoracotomy

Question 14

Other than a poor response to conservative therapy, what are some other indications for pleural drainage?

Answer 14

1) sufficient volume to cause distress
2) emphysematous character
3) fetid odor
4) cytology or biochemical evidence of sepsis

Question 15

Is there communication between the left and right pleural spaces, in horses?

Answer 15

Yes, the mediastinum is perforated and the left and right pleural spaces communicate.

Question 16

List some fibrinolytic agents used in human medicine that could be used fibrinous pleuropneumonia.

Answer 16

Streptokinase, urokinase and recombinant tissue plasminogen activator (rtPAs: alteplase and tenecteplase)

Question 17

There are 4 criteria for surgical intervention in horses with pleuropneumonia. What are these?

Answer 17

1) failure to response to antimicrobial therapy, pleural drainage and pleural lavage
2) stable systemic medical condition
3) presence of a large amount of fibrin, debris or pus in the pleural space
4) a walled-off lesion or presence of a complete mediastinum to prevent a bilateral pneumothorax

Question 18

R. equi is the most common cause of pneumonia in foals between what age? 
A) 3 weeks - 5 months
B) 3-4 months 
C) Less than 3 months
D) 8-12 months

Answer 18

A) 3 weeks - 5 months

Question 19

R. equi causes a suppurative bronchopneumonia foals. List some extra pulmonary diseases that it can also cause. (3)

Answer 19

Intestinal lesions - multifocal ulcerative enterocolitis, granulomatous or suppurative inflammation of the meds enteric and/or colonic lymph nodes

Polysynovitis - most common are tibiotarsal and stifle joints, likely resulting from a bacteremia

Ocular lesions - uveitis, keratouveitis, panophthalmitis

Question 20

Which of the following is correct about the classification of the equine herpes viruses?

A) EHV-1 and 2 are Gammaherpesvirinae
B) EHV-3 and 4 are Gammaherpesvirinae
C) EHV-1 and 5 are Alphaherpvesvirinae
D) EHV-1, 3 and 4 are Alphaherpesvirinae

Answer 20

D) EHV-1, 3 and 4 are Alphaherpesvirinae. EHV-2 and 5 are Gammaherpesvirinae

Question 21

Match the equine herpes with its disease process. EHV-1, EHV-2, EHV-3, EHV-4, EHV-5
A) Respiratory disease
B) Abortion
C) Equine herpes myeloencephalopathy
D) Equine multinodular pulmonary fibrosis
E) Unknown
F) Equine coital exanthema

Answer 21

A) Respiratory disease: EHV-1, 4
B) Abortion: EHV-1, sporadically EHV-4
C) Equine herpes myeloencephalopathy: EHV-1
D) Equine multinodular pulmonary fibrosis: EHV-5
E) Unknown: EHV-2 & 5
F) Equine coital exanthema: EHV-3

Question 22

How does EHV-1 cause abortion?

Answer 22

Vasculitis of the small arteriolar branches of the glandular layer of the endometrium causes thrombosis, microcotyledonary infarction, perivascular cuffing and transplacental spread of the virus.

Question 23

What kind of immunity is formed after a horse has been infected with equine herpes 1 or 4?

Answer 23

The protective immune response following infection is short lived. High titers of virus-neutralizing Ab before infection can reduce the amount and duration of virus shed from the nasopharyngeal but fail to prevent infection of the development of EHM or abortion.

Question 24

Intracellular equine herpes virus is susceptible to which branch of the immune system?

Answer 24

Intracellular equine herpes virus is susceptible to cytotoxic T-lymphocytes (CTLs), and is MHC Class 1 restricted. This is mediated by CD8+ lymphocytes.

Question 25

What are ways that EHV-1 evades the immune system?

Answer 25

1) Modulation of cytokines responses with subsequent effects on T- and B- cell response
2) Interference with Ag presentation by downregulation of MHC-1 expression
3) Alteration of NK-cell lysis
4) Loss of efficient chemoattraction of professional Ag-presenting cells