Post-Neonatal and Weanling Respiratory Diseases

Question 1

what parasite can cause lower respiratory disease in older foals and weanlings?

Answer 1

Parascaris equorum

Question 2

should you use antibiotics in foals with respiratory disease?

Answer 2

yes: more fragile than adults
non-infectious causes of cough are unusual in foals

Question 3

do horses with disease often have a normal CBC?

Answer 3

yes- all ages

Question 4

for what can nebulizing with gentamycin or amikacin be useful?

Answer 4

Bordatella spp

Question 5

what is Rhodococcus equi?

Answer 5

obligate aerobe
intracellular
gram positive, acid fast
pleomorphic cocco-bacillus

Question 6

when do you see disease due to Rhodococcus equi in foals?

Answer 6

1-4 months old

Question 7

where does Rhodococcus equi survive and replicate?

Answer 7

macrophages: inhibits phagosome/lysosome fusion

Question 8

what are the five mechanisms of hypoxemia?

Answer 8

V/Q mismatch
diffusion impairment
shunt
hypoventilation
low FiO2

Question 9

how long is the environment contaminated with Parascaris equorum?

Answer 9

up to 5 years

Question 10

who is at risk for Parascaris equorum?

Answer 10

young or very naive or debilitated adults
most severe on breeding farms

Question 11

what does Parascaris equorum have significant resistance to?

Answer 11

ivermectin

Question 12

what are the bacterial causes of lower respiratory disease in older foals and weanlings?

Answer 12

opportunistic: Streptococcus equi subsp zooepidemicus
Rhodococcus equi

Question 13

how common is cough with foal respiratory disease?

Answer 13

infrequent even with severe disease

Question 14

what do Bordatella species produce?

Answer 14

beta-lactamase

Question 15

what is opportunistic bacterial bronchitis and pneumonia known as?

Answer 15

snotty nose syndrome
undifferentiated distal respiratory tract infection

Question 16

what are the risk factors for lower respiratory disease in foals?

Answer 16

high stocking density
dusty housing
nadir of immunosuppression: when maternal antibodies lapse

Question 17

what is the epidemiology of Rhodococcus equi?

Answer 17

soil-borne- inhaled
10-20% farms endemic
likes warmth
only 100 organisms needed for infection

Question 18

what are the common signs of Rhodococcus equi?

Answer 18

young foals, insidious infection
fever, dyspnea, crackles, wheezes, coughing
neutrophilia, lethargy
maybe normal on auscultation

Question 19

how can you screen for Rhodococcus equi?

Answer 19

ultrasound screen
temperatures bi-weekly from 30-90 days of age
CBC with fibrinogen in a few
serum amyloid A

Question 20

what causes of hypoxemia cause a large A-a gradient?

Answer 20

V/Q mismatch
diffusion impairment
shunt

Question 21

what drugs can you use for Rhodococcus equi (intracellular)?

Answer 21

rifampin
macrolide: clarithromycin, azithromycin, erythromycin

Question 22

why should you use macrolides with caution?

Answer 22

can cause severe diarrhea and hyperthermia in foals and mares

Question 23

what is the life cycle of Parascaris equorum?

Answer 23

direct
migration

Question 24

do horses usually self-cure of Parascaris equorum?

Answer 24

yes- 18 months

Question 25

what organs does Parascaris equorum affect?

Answer 25

liver damage usually subclinical
lungs: inflammation, edema and consolidation
gut: mechanical obstruction and inflammation

Question 26

how long may infections with P. equorum be patent?

Answer 26

3 months

Question 27

what are the clinical signs of P. equorum?

Answer 27

coughing and mucopurulent nasal discharge
seldom febrile unless secondary infection
poor doers
ileus, impactions, rupture

Question 28

why should you treat adults for P. equorum?

Answer 28

may harbor enough to be infective source