Lecture 20: Equine Respiratory Diseases (MacKay) Flashcards Preview

Cardiopulmonary (Estrada-Fall 2014) > Lecture 20: Equine Respiratory Diseases (MacKay) > Flashcards

Flashcards in Lecture 20: Equine Respiratory Diseases (MacKay) Deck (79):
1

Dx/Txof guttural pouch mycosis

Dx: endoscopy, culture (Emericella, Aspergillus, etc.)
Tx: sx occlusion of affected artery or systemic and/or topical antifungal if less severe

2

guttural pouch tympany

distension of one or both guttural pouches with air. Occurs in horses <1yo

3

CS/Dx/Tx of guttural pouch tympany

-external swelling in parotid area
-dyspnea if severe
-rarely dysphagia
Dx based on CS
Tx: surgical

4

Primary sinusitis and Tx

-maxillary sinus most commonly affected
-S. equi zooepidemicus commonly involved
Tx: systemic Abx, sinus flush

5

2ary sinusitis and Tx

causes tooth root abscess
Tx: systemic abx, tooth extraction, tooth repulsion through maxillary sinus flap

6

CS of sinusitis

-unilateral nasal discharge**
-ozena
-ocular discharge
-facial sensitivity/deformity

7

Dx of sinusitis

-percussion
-rads
-endoscopy
-oral exam
-CT

8

2 main viral resp. diseases

influenza
herpes virus (rhinopneumonitis)

9

Viral resp. diseases general CS

fever, cough, nasal d/c

10

Dx of viral resp. diseases

-virus isolation
-PCR amplification***
-Serology (paired samples 10-14 days apart)
-Ag detection

11

most common cause of severe epidemics of upper respiratory disease in horses****

Equine Influenza. Comprises 40-60% of cases

12

What type of virus is equine influenza?

orthomyxovirus with an RNA genome
-only influenza type A to affect horses

13

How is level of virulence determined in equine influenza?

By some combination of Hemagglutinin (HA) and Neuaminidase (NA) immunodominant antigens which are used to penetrate the cells

14

What combos of HA and NA have been id'd in horses?

H7N7
H3N8 <---major subtype***

15

What is unique about H3N8 strain of equine flu?

subject to antigenic drift, in which HA or NA mutate so that virus can escape neutralization by antibody made to earlier strains. It likes to accumulate mutations over time

16

incubation period of equine flu

1-3 days

17

equine flu affects which pop. of horses the most?

1-3 year old horses in training

18

pathogenesis of equine flu

1) aerosol infection
2) adhesion to resp. ep.
3) desquamation of ciliated cells
4) decreased mucociliary clearance

19

morbidity/mortality of equine flu?

high morbidity (100%), low mortality

20

CS of equine flu

-acute onset fever
-anorexia, depression
-dry cough
-serous nasal discharge
-submandibular lymph node enlargement

21

Dxof equine flu

-viral isolation (difficult)
-RT-PCR***
-serology (retrospective only)
-influenza A Ag detection Kit: rapid

22

Possible complications of equine flu

-bacterial pneumonia/pleuropneumonia
-myositis
-myocarditis

23

how long does it take tracheal ep. to restore after equine flu?

1 month, but horses appear healthy after 1 week

24

Tx of equine flu

3 wks rest
NSAIDs for fever
Abx for 2ary bacteria pneumonia
Antiviral usually NOT warranted

25

How long does immunity last following natural equine flu infection?

1 yr

26

Types of vax for equine flu

1) killed IM
-effective for 3-4 mo
-provides transient systemic IgG response
-not effective in presence of maternally-derived Ab
-does not prevent infection/shedding
2) MLV IN
-protect 6-12mo
-does not provide systemic response
3) Canary Pox Vector Vax
-use in foals of vaccinated dams
-provides robust immune response

27

Effects of Equine Herpesvirus-1 (EHV-1)***

-abortion
-perinatal dz and death
-neuro
-resp. dz
*viremia (virus in blood) is common**

28

EHV-2 effects

-mild resp. signs
-immunosuppression?
-keratoconjunctivitis

29

EHV-3 effects

equine coital exanthema (genital horsepox)

30

EHV-4 effects***

respiratory disease (rhinopneumonitis)

31

EHV-5 effects

Equine Multinodular Pulmonary Fibrosis (eventually fatal)

32

What percent of horses carry EHV-1 or 4 in a latent state?***

85% (in lymph nodes, trigeminal ganglia)

33

path. of EHV-1 and 4

-young horses
-responsible for 15-20% of outbreaks of URT dz!
-up to 85% of horses are carriers!!**
-acquired via inhalation or recrudescence of a latent infection
-incubation period 2-10 days
-viremia common in EHV-1 infections

34

Dx of EHV-1 and 4

-virus isolation or PCR amplification <--**
-serology (not important)

35

vax. for EHV-1 and 4

inactivated or modified live vaccines available for EHV-1, 4, or both
-labeled to prevent abortion

36

foal pneumonia***

-leading cause of morbidity and mortality!!
-inhalation of aerosolized or dust-borne pathogens
-causes bacteremia and hematogenous spread of bacteria to the lungs in neonates (1-10 mo.)

37

CS of foal pneumonia

-cough
-bilateral nasal d/c
-fever
-inc. resp. rate
-resp. distress

38

Dx of foal pneumonia

-abnormal lung sounds
-hematology: neutrophilic leukocytosis, hyperfibrinogenemia
-rads and ultrasonography
-tracheobronchial aspiration: mainly degenerate neutrophils +/- bacteriaon cytology

39

most common cause of foal pneumonia***

streptococcus equi subs. zooepidemicus

40

agents of foal pneumonia

strep equi zooepidemicus***
Rhodococcus equi
others: Pasteurella, E. coli, Klebsiella, Actinobacillus,etc.

41

tx of foal pneumonia

Abx:
-Ceftiofur (broad spec)
-Penicillin (for S. zooepidemicus)
-Trimethoprim-sulfa (oral, mostly useless now)
-Penicillin-aminoglycoside
O2 therapy

42

Duration of therapy for foal pneumonia based on:

-resolution of CS
-normal WBC count and fibrinogen concentrations
-imaging techniques (rads, ultrasound)
Only stop tx when everything is normal!

43

prognosis of foal pneumonia

usually complete recovery if dx/tx early

44

rhodococcus equi pneumonia path.

-Gram + facultative intracellular pathogen (NOT obligate!)
-can survive and replicate in macs
-normal inhabitant of soil
-infection by inhalation
-can be devastating dz
-usually affects foals 1-6 mo.

45

CS of rhodococcus equi pneumonia

-bronchopneumonia
Extra-pulmonary disorders:
-intestinal manifestations --> weight loss
-non septic immune-mediated polysynovitis
-septic arthritis and osteomyelitis
-uveitis
-ulcerative lymphangitis, cellulitis
-abscesses

46

Dx of rhodococcus equi pneumonia

-hematology: neutrophilic leukocytosis, hyperfibrinogenemia
-rads/ultrasound
-tracheobronchial aspiration: degenerate neuts, Gram + coccobacillus on gram stain, culture, PCR***

47

only way to make definitive dx of rhodococcus***

tracheobronchial aspiration

48

Tx of rhodococcus equi pneumonia

long-term therapy of macrolide and rifampin abx (able to penetrate caseous material and cells)

49

side effect of macrolides

suppress sweating --> hyperthermia

50

prog. of rhodococcus equi pneumonia

survival rates b/w 60-80%
affected foals less likely to race, but perform as well

51

prevention of rhodococcus pneumonia

-decrease size of infective challenge (i.e. prevent grass degradation)
-earlier recognition/close monitoring
-hyperimmmune plasma

52

pneumonia

infection involving the lung parenchyma

53

pleuropneumonia

pneumonia or lung abscess that extends to and involves the visceral pleura

54

most common cause of pleuropneumonia

bacteria

55

causes of pleural effusion

-pneumonia
-pleuropneumonia
-hemothorax
-chest wound
-neoplasia
-hypoproteinemia
-CHF

56

Path. of pneumonia/pleuropneumonia

viral infection/toxic gases/stress/malnutrition/general anesthesia --> decreased # and bactericidal activity of alveolar macs --> pneumonia/pleuropneumonia

57

CS of pneumonia/pleuro.

-fever*
-anorexia, depression*
-tachypnea, resp. distress
-soft cautious cough
-pain in thorax
-bilateral nasal d/c
-fetid breath
-ventral edema
-colic-like signs
-weight loss if chronic
-won't lay in lat. recumb.

58

infectious agents of pneumonia/pleuro.

-S. equi zooepidemicus
-Gram - bacteria (Pastuerella, E. coli, Klebsiella, Pseudomonas, Enterobacter)
-Anaerobes (Bacteroides, Peptostrep., Eubacterium)

59

Dx of Pneumonia/Pleuro.**

-auscultation: decreased lung sounds ventrally and presence of pain
-percussion: horizontal line
-pleurodynia (pleural pain)
-hematology: leukopenia followed by leukocytosis, hyperfibrinogenemia
-ultrasonography, rads
-tracheobronchial aspiration***
-cytology: degenerate neuts +/- bact.
-culture: more likely to yield + culture than pleural fluid
-thoracocentesis

60

Tx of pnuemonia/pleuro:

1) Abx
-initially broad-spec, then based on culture/sensitivity
-long-term usually required
2) Pleural drainage
-removal of exudate
-re-expansion of lungs
*Go all out on Day 1!!*
3) Supportive care
-fluids
-prevention of endotoxemia
-analgesia
4) thoracotomy and rib resection
-chronic cases
-manual removal

61

Complications of pneumonia/pleuro.

-endotoxemia
-thrombophlebitis (vein swelling)
-laminitis
-pleural and/or pulmonary abscess form.
-pneumothorax
-pericarditis (rare)

62

Prog. of pneum/pleuro.

38-75% survival depending on how quickly tx is started
40-60% of survivors race

63

Exercise-Induced Pulmonary Hemorrhage (EIPH)

presence of blood in the airways after intense exercise/pulmonary hemorrhage (usually caudodorsal lung fields)

64

Incidence of EIPH

5% of race horses have epistaxis
Up to 90% of race horses have EIPH!

65

EIPH effect on performance**

unlikely; rule out all other causes!

66

Dx of EIPH

-endoscopy
-cytology (TBA or BAL): hemosiderin-laden macs
-rads: opacities in caudodorsal lung fields

67

path. of EIPH

failure of pulmonary capillaries during exercise when pressure exceeds 70 mmHg

68

Tx of EIPH

furosemide (loop diuretic)
-decreases pulmonary capillary pressure
nasal strips

69

Heaves aka

RAO (recurrent airway obstruction)
COPD

70

heaves affects young/mature horses?

mature >3 yo

71

Path. of Heaves

fungi/molds/endotoxins/allergens --> hypersensitivity/non-specific inflammation --> bronchiolitis, neutrophilic airway infiltration, excess mucus, bronchoconstriction
*genetic disposition also possible*

72

Path.of hypersensitivity reactions in Heaves

1) Type I --> IgE, mast cell degranulation
2) Type III --> IgG or IgM, immune complexes

73

CS of mild heaves

intermittent cough
exercise intolerance
abnormal lung sounds
mild increase in resp. rate

74

CS of severe heaves

resp. distress
abd effort during expiration (heavy line)
weight loss

75

When is fever present in Heaves?***

ONLY when there is a 2ary bacterial infection

76

Dx of heaves***

History/PE:
-increased expiratory effort
-crackles/EXPIRATORY wheezes
-lack of fever**
-normal WBC count and fibrinogen
Bronchoalveolar lavage:
-well-preserved neuts**
Response to bronchodilators

77

Tx of Heaves

*NOT a cureable disease*
Env. management: reduce dust**/allergen exposure
Corticosteroids: most effective
Bronchodilators (supportive)

78

most effective therapy for heaves

corticosteroids

79

Which aerosol therapy drugs get down to distal airways best?

AeroHippus, Torpex