Respiratory Infections IV (27)

Question 1

What is strangles? What are its negative effects?

Answer 1

one of the most important diseases of horses in developed countries

disruption of management of commercial horse establishments
time necessary to treat affected horses
esthetic unpleasantness

Question 2

What is the causative agent of strangles?

Answer 2

streptococcus equi subsp. equi

Question 3

T/F: S. equi can cause disease in other species

Answer 3

FALSE - only in equids

Question 4

What is the epidemiology of strangles?

Answer 4

highly contagious disease that affects horses of all ages
more common in young animals

Question 5

What are clinical findings of strangles?

Answer 5

acute onset of fever, anorexia, depression

submandibular and pharyngeal lymphadenopathy with abscessation and rupture

copious purulent nasal discharge

metastatic infection in other organ systems

Question 6

What are lesions of strangles?

Answer 6

caseous lymphadenopathy with rhinitis and pharyngitis, pneumonia, and metastatic infections in severe cases

Question 7

How do you diagnose s. equi?

Answer 7

culture of it

PCR

Question 8

How do you treat strangles?

Answer 8

systemic administration of penicillin and local treatment of abscesses

Question 9

What are the morphological characteristics of strangles?

Answer 9

gram-positive
facultative anaerobic
catalase and coagulase negative
highly adapted to equidae

Question 10

S. equi is coagulase [positive/negative] and urease [positive/negative]

Answer 10

both NEGATIVE

Question 11

Who all does s. equi affect?

Answer 11

horses, ponies, donkeys, and mules - equids

Question 12

S. equi is a(n) _______ parasite of horses and all infections are attributable to transmission from infected horses either _____ or by ______

Answer 12

obligate

directly or by fomites

Question 13

Describe immunity regarding s. equi

Answer 13

resistance to the disease is associated with the production of serum and mucosal antibodies to the streptococcal M protein (SeM)

animals that have previously had the disease are less likely than naiive animals to develop the disease on subsequent exposure

Question 14

How many horses do not develop protective immunity from strangles?

Answer 14

25%

Question 15

The virulence of s. equi is attributable to the presence of ______

Answer 15

M proteins on the surface of bacteria

hyaluronic acid capsule

production of a leukocidal toxin

Question 16

M proteins of strangles are associated with _____

Answer 16

adhesion to oral nasal and pharyngeal tissue
invasion of pharyngeal tonsils
evasion of innate immunity

Question 17

What part of s. equi provides resistance to phagocytosis?

Answer 17

capsule

Question 18

What in s. equi causes damage? What kind?

Answer 18

toxins

cell damage

Question 19

Migration of neutrophils into lymph nodes regarding s. equi causes ______

Answer 19

swelling and abscessation

Question 20

Because s. equi causes abscesses, what eventually happens?

Answer 20

eventually rupture and drain

Question 21

How long is s. equi shed nasally?

Answer 21

2-3 weeks

Question 22

If an equid dies from strangles (which is rare), what is the reason?

Answer 22

due to pneumonia caused by aspiration of the infected material

asphyxiation secondary to upper airway obstruction

impairment of organ function by metastatic infection

Question 23

What disease can follow after strangles? What is it associated with?

Answer 23

purpura hemorrhagica

associated with high serum antibody titers to SeM

Question 24

What does strangles manifest as?

Answer 24

an acute disease of varying severity, infection of retropharyngeal lymph nodes and guttural pouches

a chronic disease associated with metastatic infection of organs distant from respiratory tract

Question 25

Severity of strangles varies how?

Answer 25

age
immune status
size of onoculum
duration of exposure

Question 26

Why is it called strangles?

Answer 26

derives from the enlarged retropharyngeal lymph nodes and guttural pouches causing respiratory distress in severely affected animals

Question 27

What is the acute form of strangles characterized by?

Answer 27

mucopurulent nasal discharge
abscessation of submandibular and retropharyngeal lymph nodes

Question 28

A horse suddenly has an onset of symptoms like anorexia, depression, and serous nasal discharge that is becoming copious and purulent. Another horse 1-3 weeks ago was also ill with this. What is the disease and causative agent? Be specific

Answer 28

strangles - acute form

s. equi

Question 29

What manifestations of strangles is this foal experiencing?

Answer 29

enlarged, abscessed submandibular LN

Question 30

What are clinical findings of strangles?

Answer 30

swelling of lymph node occurring 3-4 days
serum exudate in 10 days and rupture shortly afterwards

Question 31

Regarding strangles, what can retropharyngeal lymph node abscesses rupturing cause?

Answer 31

can rupture into the guttural pouch, causing guttural pouch empyema and formation of chondroids

Question 32

This endoscope is focused in the guttural pouch of a horse with strangles. What are we seeing?

Answer 32

chondroids

Question 33

What is the most common fatal complication of strangles?

Answer 33

the development of suppurative necrotic bronchopneumonia (aspiration of pus from ruptured abscesses)

Question 34

What is metastatic infection regarding strangles? What is it also called?

Answer 34

formation of abscess in any organ or body site but most commonly in the lungs, mesenteric lymph nodes

bastard strangles - a serious complication

Question 35

What hypersensitivity disease can occur after infection with strangles? When does it arise?

Answer 35

purport hemorrhagica - considered an immune-mediated disease which occurs in a subset of affected horses 1-3 weeks after the initial illness

Question 36

A horse recently recovered from a respiratory infection (s. equi) and is now experiencing these symptoms. What could possibly be the cause of this?

Answer 36

purpura hemorrhagica

Question 37

How do you diagnose s. equi?

Answer 37

clinical signs and history of exposure

microscopic exam of abscess aspirates

gram-positive cocci in chains - streptococcus

Question 38

When viewing s. equi microscopically, what do you see?

Answer 38

gram-positive cocci in chains

Question 39

How do you confirm diagnosis of strangles?

Answer 39

nasopharyngeal swabs
discharges from abscesses
guttural pouch lavage

PCR

culture

Question 40

Describe the cultures of s. equi

Answer 40

left: mucoid colonies
right: beta-hemolysis

Question 41

How do you treat strangles?

Answer 41

PENICILLIN
quarantine
live-attenuated intranasal vaccine
avoid overcrowding and mixing of different age groups