Pathology and Microbiology of Respiratory Infections - Horses Flashcards Preview

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Flashcards in Pathology and Microbiology of Respiratory Infections - Horses Deck (19):
1

bacteria

β-haemolytic streptococci
Rhodococcus
Actinobacillus
Mycoplasmas

2

viruses

Equine influenza virus
Equine herpesvirus types 1 and 4
Equine arteritis virus (EVA) - notifiable

3

strep. equi

Gram-positive; obligate parasite of horses
Carried without disease in nasopharynx
Strongly β-haemolytic with mucoid colonies
Hyaluronic acid capsule which become matt (hyaluronidase)
Causes strangles in horses & ponies.
Circulating antibody raised by infection or vaccination - mucosal immunity probably essential for protection

4

strep. equi infection pathology

Suppurative lymphadenitis and guttural pouch empyaema (site of long-term carriage)

5

strep. zooepidemicus

Affects many animal species - primarily the horse & dog
Inhabits skin, N/P, respiratory mucosa
2° invader post viral disease in horses, wound infections

6

strep. pneumoniae

Some evidence this is an occasional cause of respiratory disease in the training horse
a-haemolytic

7

rhodococcus equi

Gram-positive rod, variably acid fast, Actinomycete group
Naturally present in soil & intestine of horses
Persistent in manure for long periods

8

rhodococcus equi - pathology in foals

chronic suppurative bronchopneumonia in foals between 2-6months
complex lipid cell wall - resists host digestion
foci of caseous necrosis in lungs
lesions often extensive before clinical signs become apparent
high mortality rate of 40-80%
bronchial lymph nodes may also contain caseating foci
dissemination to other viscera can occur esp abd organs e.g. liver and intestine
Adult horses are immune

9

actinobacillus sp.

Adult horses - thoroughbreds
Tracheal washes taken during infection

10

mycoplasmas

Recent efforts to find mycoplasma involvement in low-grade resp. disease
M. felis considered relevant in pleuritis and predisposition to 2° infect.
Other mycoplasmas may emerge as primary agents

11

equine influenza virus (EIV)

Infection of URT that may spread to LRT and cause bronchitis and bronchiolitis
Cough, pyrexia, depression
Secondary infections: Strep., Staph., Klebsiella
vaccine needed for racing

12

equine herpesvirus (EHV)

Infection of URT
Nasal discharge, coughing, pyrexia
Inactivated vaccines containing EHV-1 and EHV-4 available

13

equine herpesvirus (EHV) - EHV-1

resp disease
abortion + paresis(weakness)

14

equine herpesvirus (EHV) - EHV-4

mainly resp disease
rarely abortion

15

equine herpesvirus (EHV) - EHV-5

equine multinodular pulmonary fibrosis

16

equine arteritis virus (EAV)

Arteriviridae
Infection of URT, systemic spread + infection of endothelial cells + macrophages (arteritis)
May spread to lung in macrophages + cause interstitial pneumonia
Nasal discharge, conjunctivitis, oedema
Arteritis causes oedema and abortions
Frequently subclinical if less virulent strains

17

Mycoses: equine guttural pouch mycosis

Aetiology - Aspergillus nidulans
Severe bleeding from the nose/dysphagia

18

Mycoses: equine guttural pouch mycosis - diagnosis

Endoscopy
radiology
serology
Culture
Microscopy

19

Mycoses: equine guttural pouch mycosis - treatment

Local delivery of antifungal
Ligation of carotid artery
?systemic azole antifungal