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Flashcards in Coughing in Horses Deck (56):
1

Coughing in foals + weanlings - DDX - URT

EHV 1+4
equine influenza
strep. equi equi

2

Coughing in foals + weanlings - DDX - LRT

EHV 1+4
equine influenza
undifferentiated resp tract infection
strep zooepidemicus
rhodococcus equi
strep. equi equi
parascaris equorum

3

bacterial pneumonia - causes

strep zooepidemicus + rhodococcus equi most important
actinobacillus, klebsiella, staph aureus, bordatella, mycoplasma

4

bacterial pneumonia - clinical signs

mild pyrexia
cough
auscultable changes

5

bacterial pneumonia - diagnosis

history, clinical signs, further tests

6

bacterial pneumonia - further tests

endoscopy - mucopurulent exudate in trachea
radiography - bronchointerstitial pattern
cytological exam of BAL or tracheal aspirate - incr degenerate neurophils with intracellular bacteria

7

bacterial pneumonia - treatment

antibiotics
rest + dust free environment

8

Coughing in adults - DDX - URT

EHV 1+4
equine influenza
strep. equi equi
EVA

9

Coughing in adults - DDX - LRT

EHV 1+4
equine influenza
strep. equi equi
EVA
equine rhinoviruses
strep zooepidemicus
strep pneumonia
pasteurella/actinobacillus

10

epidemiology - URT

less common than LRT
mainly young horses

11

epidemiology - LRT

common in all racing age groups
bacterial + viral infection can occur together

12

clinical signs - URT

fever
nasal discharge
coughing
enlarged submandibular LN

13

clinical signs - LRT

(fever, nasal discharge)
coughing
mucoid tracheal secretion +/- haemorrhge
poor performance

14

Equine herpes virus 1 + 4

endemic in UK + worldwide
75% have latent infection
stress may activate latent infection
1st exposure as foal from the mare
immunity short

15

site of latency for EHV 1+4

bronchial + submandibular LNs
trigeminal ganglia

16

Equine herpes virus 1 + 4 - pathogenesis

inhalation
replicates in URT epithelium - disseminates to LRT - transports to other organs by T lymphocytes
viaemic for 3 weeks
vasculitis, neurological disease, abortion

17

equine influenza virus

worldwide
highly infectious - via aerosol
vaccinated animals susceptible to infection within 2-3 months
partial immunity may stop clinical signs but allow spreading

18

equine influenza virus - pathogenesis

epithelial cells of upper + lower airways
laryngitis, tracheitis, bronchitis, bronchiolitis
loss of ciliated epithelium
compromise of mucocillary mechanism

19

how can URT infection be indentified

clinical signs

20

how can LRT infection be indentified

clinical signs/poor performance
endoscopy + LRT samples - incr degenerate neutrophils, mucopus
haematology - neutropenia/philia, lymphopenia/cytosis, hyperfibrogenaemia

21

how to definitively diagnose EHV 1+4

blood
nasopharyngeal swab
serology - paired samples

22

treating viral infection

isolate
limit stress
NSAIDs - limit pyrexia + improve appetite
specific anti-virals
monitor for secondary infection

23

treating bacterial infection

antibiotics
improve environment, decr dust + stress
anti-pyretics
mucolytics
bronchodilators

24

Equine influenza vaccine

often changing + not entirely effective
necessary for racing - annual booster or within 6m + 21d of competition

25

EHV 1+4 vaccination

natural immunity short - unlikely to improve with vaccine
modified live or inactivated vaccine

26

other causes of coughing - common

RAO, SPAOPD, IAD

27

other causes of coughing - fairly common

aspiration pneumonia, pleuropneumonia, LSHF, epiglottic entrapment, URT foreign body

28

other causes of coughing - uncommon

TB, lungworm, tracheal stenosis/collapse, inhalation pneumonia, interstitial pneumonia, neoplasia

29

recurrent airway obstruction (RAO) - define

aka chronic obstructive pulmonary disease (COPD)
naturally occuring LRT disease - reversible airway obstruction
neutrophil accumulat
bronchospasmion
mucous production
life long disease

30

RAO - pathogenesis

spores + allergens in bronchioles - immune reaction - types 1,2+4
causes bronchoconstriction, mucous production + airway infl

31

RAO - acute clinical signs

incr resp effort
double expiratory effort/dyspneoa

32

RAO - chronic clinical signs

varies in severity
poor performance
hypertrophy of abdominals

33

RAO - diagnosis

history + PE
tracheal wash/bronchoalveolar lavage + rule out bacterial pneumonia
radiography/ultrasonography
endoscopy - assess infl + tracheal aspirate
cytology - incr cellularity + mucous, non-degenerate neutrophils, curshmann's spirals

34

4 areas for RAO treatment

environment
reverse bronchoconstriction
decr pulmonary infl
decr mucous accumulation

35

Summer pasture associated pulmonary disease (SPAPD)

as for RAO except from management
allergens are pasture based so affected horses should be stabled

36

inflammatory airway disease (IAD)

excessive mucous in airway
may have cough/poor performance but often subclinical

37

IAD - causes - bacterial

strep zooepidemicus
strep pneumoniae
actinobacillus
mycoplasma

38

IAD - diagnosis

endoscopy to see tracheal mucous + cytology of tracheal aspirate

39

IAD - treatment

antibiotics
interferons
corticosteroids
decr dust

40

Rhodococcus equi

gram +ve, widespread in environment
obligate aerobe, doesn't multiply within the gut
accumulates in the gut + faeces
survives in soil for at least 12 months in hot dry conditions

41

Rhodococcus equi - Epizootiology

Spread via inhalation of soil/faeces, also detected in
exhaled air from infected foals
dusty paddocks and stables
incomplete manure removal
endemically affected farms
Seasonal – late spring/summer
High aerosol challenge + high no. of susceptible foals

42

Rhodococcus equi - Pneumonia - clinical effects

Affects foals 1-6 months old
Scavenged by alveolar macrophages, but not killed
Destruction of macrophages - pyogranulomatous response
Bronchopneumonia with widespread abscess formation

43

Rhodococcus equi - Pneumonia - clinical signs

Anorexia
Depression
Fever
Dyspnoea, tachypnoea
Cough
Varies from insidious to extremely acute onset
Subacute form - May be found dead or with acute resp distress + pyrexia

44

Rhodococcus equi - Diagnosis

Fibrinogen
Neutrophilia
tracheal wash
Culture
gram-stain cytology, Serology, PCR VapA gene
radiography, Ultrasonography
Post mortem

45

Rhodococcus equi - Intestinal Form

74% foals with R equi have extrapulmonary disease
Most commonly GI: 48% respiratory + intestinal
4% intestinal only
ulcerative enterocolitis, mesenteric lymphadenitis, abscess formation, secondary peritonitis
Reduced survival cf respiratory alone

46

Rhodococcus equi - Intestinal Form - clinical signs

Depression and Fever
Diarrhoea
Colic
Weight loss/failure to grow
Poor prognosis

47

Rhodococcus equi - Intestinal Form - diagnosis

R equi in faeces is not diagnostic
Farm Hx, clinical signs and haematology
Post-mortem examination

48

Rhodococcus equi - treatment - antibiotic selection

erythromycin + rifampin
Clarithromycin or azthromycin with rifampin
combinations decr likelihood of resistance

49

Rhodococcus equi - prevention

Difficult since the organism is shed in faeces
housing - clean + dust free
Isolate sick foals
Prophylaxis with hyperimmune plasma
No effective vaccine

50

Equine Rhinovirus - epidemiology + clinical signs

Can be isolated from asymptomatic horses as well as those with signs of URTI
Most common in young horses
Subclinical or mild URT signs

51

Equine Rhinovirus - diagnosis + treatment

Diagnosis – virus isolation from NP swab
Treatment - symptomatic

52

Equine Viral Arteritis - transmission

venereal infection
contact with aborted foetuses + products of parturition
aerosol
Reservoir of infections - Stallions - chronic shedders

53

Equine Viral Arteritis - pathogenesis

replicates in macrophages - LN - leukocyte-associated viremia
Localises in endothelial cells esp + epithelium of certain tissues esp the adrenals, seminiferous tubules, thyroid, and liver

54

Equine Viral Arteritis - clinical signs

Often none
abortion and still birth
Fever, anorexia, oedema, lacrimation, conjunctivitis, nasal discharge, coughing
Necrotising arteritis oedema and haemorrhage

55

Equine Viral Arteritis - diagnosis and treatment

Blood samples, nasal swabs and semen for isolation of virus or detection of the viral
RNA by PCR
Serology
Treatment - Symptomatic

56

Equine Viral Arteritis - prevention

vaccine