Equine Strangles

Question 1

how quickly do the mandibular/suprapharyngeal lymph nodes drain the tonsils?

Answer 1

within hours

Question 2

what are the clinical signs of Streptococcus equi subsp equi?

Answer 2

fever
anorexia
depression
lymphadenopathy
rhinitis
nasal discharge
abscesses

Question 3

which lymph nodes are impacted by strangles?

Answer 3

submandibular
retropharyngeal
parotid
cranial cervical lymph nodes

Question 4

where can you sample for strangles?

Answer 4

nasal swab
nasopharyngeal wash
guttural pouch wash
abscess aspirate

Question 5

what is the best sample to take for strangles?

Answer 5

aspirate of mature abscessed lymph node

Question 6

is PCR or culture more sensitive?

Answer 6

PCR

Question 7

what does the PCR look for?

Answer 7

DNA sequence for SeM (anti-phagocytic M protein)

Question 8

how many false negatives are there with culture?

Answer 8

40%

Question 9

what is serology looking for?

Answer 9

systemic antibody to SeM

Question 10

what should you not do with a high or very high serology for systemic antibody to SeM?

Answer 10

do not vaccinate
suspect purpura hemorrhagica or metastatic

Question 11

should you use antibiotics for lymph node abscessation?

Answer 11

no- now contraindicated

Question 12

what are the negatives of using penicillin for early clinical signs of strangles?

Answer 12

often just returns
no protective immunity

Question 13

how long does nasal shedding usually last?

Answer 13

2-3 weeks
can last years

Question 14

what does disease severity correlate with?

Answer 14

dose and frequency of bacterial challenge
why should isolate cases!

Question 15

what are the steps of outbreak management?

Answer 15

report
test
quarantine
hygiene

Question 16

is strangles reportable?

Answer 16

yes- in most states

Question 17

what are the most common causes of outbreaks?

Answer 17

apparently healthy shedders

Question 18

should you vaccinate affected animals with strangles?

Answer 18

no

Question 19

what percentage of horses with strangles develop good immunity?

Answer 19

75%
limited time: 2 years

Question 20

what is prevention like?

Answer 20

very difficult
isolate new horses for 3 weeks
vaccination

Question 21

what are the main problems with the intranasal vaccine?

Answer 21

occasional residual virulence
accidental IM abscesses

Question 22

what are the complications of strangles?

Answer 22

carrier status
metastatic/bastard strangles
purpura hemorrhagica
myopathy

Question 23

what can you use to diagnose prolonged carriers?

Answer 23

endoscopy
pharyngeal wash
not serology

Question 24

what is the mortality rate of metastatic strangles?

Answer 24

62%

Question 25

what is purpura hemorrhagica?

Answer 25

type III immune: aseptic necrotizing vasculitis

Question 26

what do the virulence factors cause with the immune system?

Answer 26

ineffective neutrophil response

Question 27

when does strangles shed?

Answer 27

1-2 days after first fever

Question 28

what is the fever like with strangles?

Answer 28

high and persistent tends to resolve when abscesses rupture

Question 29

how long do the abscesses take to rupture?

Answer 29

1-4 weeks

Question 30

what do abscesses always do?

Answer 30

neutrophilic leukocytosis hyperfibrinogenemia serum amyloid A elevated in more acute hyperglobulinemia similar response in R. equi

Question 31

how are samples ranked for diagnosis of strangles?

Answer 31

aspirate of mature abscessed lymph node > guttural pouch wash > pharyngeal wash > nasal swab

Question 32

is culture considered gold standard for diagnosing strangles?

Answer 32

no- 40% false negatives

Question 33

what does a weak positive on serology indicate?

Answer 33

very recent or residual or vaccinal exposure

Question 34

does antibiotic treatment increase risk of metastatic strangles?

Answer 34

no

Question 35

which horses with strangles should get antibiotics?

Answer 35

depressed, anorexic, dyspneic pregnant mares, foals not nursing: maybe cranial nerve signs

Question 36

how can you establish horses clear of strangles?

Answer 36

nasal swabs: three negatives at 5-7 day intervals guttural pouch/nasal wash: one negative may be enough both with PCR

Question 37

what should you do once an animal has strangles on a farm?

Answer 37

stop all movement on/off segregate groups, rectal temps on all twice daily all horses potentially contagious for at least 6 weeks after secretions dry do not vaccinate affected animals

Question 38

why might older horses develop mild disease?

Answer 38

persistent immunity can still transmit

Question 39

what do you need to reach with the intranasal vaccine?

Answer 39

pharyngeal and lingual tonsils

Question 40

how long can an animal be positive on nasal wash for strangles after vaccination?

Answer 40

6 weeks

Question 41

what percentage of animals become prolonged carriers of strangles?

Answer 41

10%

Question 42

what is in the guttural pouch of carriers?

Answer 42

empyema chondroids

Question 43

what can you give to aid in treatment of empyema in prolonged carriage?

Answer 43

20% acetylcysteine

Question 44

how likely is metastatic strangles to occur?

Answer 44

2-20% of cases

Question 45

how can you treat metastatic strangles?

Answer 45

prolonged antibiotics- 2.5 months some surgical

Question 46

how can you prevent purpura hemorrhagica?

Answer 46

do not vaccinate for 1-2 years after natural infection or if high titers happens 2-4 weeks after other respiratory infections too