Equine respiratory diseases Flashcards
1
Q
What is the LRT?
A
lungs from primary bronchi to alveoli
2
Q
What is URT?
A
nares nasal passages pharynx larynx guttural pouches trachea
3
Q
What divides the guttural pouch into two compartments, which is the bigger compartment?
A
stylohyoid bone
medial compartment
4
Q
Wht artery run over the guttural pouch?
A
external maxillary artery
internal carotid artery
external carotid artery
5
Q
What nerves run over teh guttural pouch?
A
VII, IX X, XI, XII
6
Q
What are the three main guttural puch diseases?
A
tympany
mycosis
empyema
7
Q
What is the cause of guttural puch tympany?
A
- dysfunction of the nasopharyngeal orifice (1 way valve)
- secondary to upper airway infections/inflam
- congenital (not that common)
8
Q
What are the clinical signs of guttural pouch tympany?
A
- non-painful elastic swelling in the retropharyngeal area!!
- respiratory noise
- cough and dysphagia
9
Q
What is the treatment for guttural pouch tympany?
A
- surgery
- fenestration of median septum (unilateral)
- creation of salpinogopharyngeal fistula
10
Q
What are the guttural pouches?
A
caudoventral diverticula of the auditory tubes
11
Q
What is a possible function of guttural pouches?
A
cooling of arterial blood suply to brain
12
Q
What is the capacity of each guttural pouch?
A
300mL
13
Q
What is the lining of the guttural pouches?
A
secretory mucosa lining and thinner than in nasopharynx
14
Q
Why can guttural pouch tympany cause resp noise?
A
enlargement of guttural pouch can bulge above the epiglottis?? because it bulges ventrally into nasopharynx?
15
Q
What is the most common guttural pouch disease?
A
guttural pouch empyema
16
Q
What is guttural pouch empyema secondary to?
A
- upper resp infections (strep equi)
17
Q
What are the clinical signs of guttural pouch empyema?
A
- intermittened nasal discharge that is worse when head is lowered
- coughing and/or dysphagia in some cases
- can see white on nose due to chronic nasal discharge
18
Q
What is treatment for guttural pouch empyema?
A
if there is only pus, daily drainage and lavage. Antibiotics?
if there are chondroids–>flush, basket retrieval, surgery
19
Q
Why is it important to have a horse’s head down (heavy sedation) when flushing guttural pouch?
A
to prevent aspiration pneumoniae
20
Q
What is a radiographic way to diagnose guttural pouch empyema?
A
a fluid line on radiograph
21
Q
Why is important to flush everything out in guttural pouch empyema?
A
because won’t resolve, antibiotics won’t work
22
Q
What does inspissated pus become?
A
chondroids
23
Q
What is the most important cause of serious epistaxis that is not related to exercise or trauma? (important)
A
guttural pouch mycosis
24
Q
Is there any warning that a horse will die of hemorrhage from mycosis?
A
Usually they have several bouts of hemorrhage before a fatal episode
25
What is the cause of guttural pouch mycosis?
aspergillus in the dorsocaudal region of the medial compartment
26
What is treatment for guttural pouch mycosis?
1. horses with epistaxis the affected artery should be identified and surgically occluded
27
What can be difficult to prevent with guttural pouch mycosis?
aberrant vessel anatomy
thrombi
infection and persistent nerve disfunction
28
What can be the survival of a horse with guttural pouch mycosis that is treated?
can exceed 90%
29
What nerves run over guttural pouch?
VII, IX, X, XI, XII
cranial cervical ganglion
sympathetic trunk
30
What can be the signs of guttural pouch mycosis?
```
bleeding from (external carotid, internal carotid, external maxillary)
nerve deficits
```
31
What is the cause of strangles?
streptococcus equi equi
| a gram + beta hemolytic strep
32
What is strangles characterized by?
URT inflammation an lymph node aspiration
33
Who usually gets strangles?
young horses, esp in breeding farms
34
What lymph nodes are often enlarged?
retropharyngeal
| submandibular
35
When does nasal shedding begin in strangles?
2-3 days after onset of fever and persists 3 wweeks in most animals but can be longer
36
Why should you isolate horses that have strangles? How do you check animals that will start shedding?
Because they will have nasal discharge (shedding)
| check rectal temperature for fever
37
How often does carrier state occur in strangles?
up to 10%
| don't show clinical signs but hide infection in guttural pouch
38
How would you ID a strangles carrier?
sample from guttural pouch
39
What are the clinical signs of guttural pouch empyema?
1. abrupt onset of fever
2. mucopurulent nasal discharge
3. acute swelling and abscess formation in submandibular and retropharyngeal lymph nodes
4. severity of disease depends on immune status, challenge load and duration
40
How is strangles diagnosed?
1. culture--the gold standard
with nasal swa, nasal wash, guttural pouch wash, pus from abscesses
2. PCR--DNA sequence of SeM (antiphagocytic M protein)
3 times more sensitive than culture
dead or alive organisms
3. serology--ELISA. Detects antibodies from vaccination AND infection. serum titers peak at 5 weeks and remain high for at least 6 months
41
If a person wants to take a horse to a show after strangles, should you use culture or PCR?
culture, because although PCR is more sensitive, it can detect dead organisms and is not relevant for disease shedding potential
42
What is treatment for strangles if horsees have early clinical signs (fever, depressed, purulent nasal discharge)
antimicrobial therapy may arrest disease and control outbreak.
if horse remains exposed to infected horses, high chance of relapse if discontinue treatment
43
What is treatment for strangles if horses have lymph node abscessation?
1. enhance maturation and drainage of abscesses
2. isolation
3. hot packs or poultice
4. if needed lance abscess
5. flush and drain regularly
44
What is treatment for strangles if horses have lymph node absecssation and advanced clinical signs?
antimicrobial therapy
45
What is treatment of horse exposured to strangles?
may treat with antibiotics in hopes of preventing seeding of lymph nodes
46
Why would you be worried about using antimicrobials in the face of strangles infection?
could cause bastard strangles
47
What are complications of strangles?
1. purpura hemorrhagica
2. metastatic spread of infection
3. myositis
4 .agalactia
48
What is the mechanism of purpura hemorrhagic in horses that had strangles?
1. immune mediated process
| 2. aseptic necrotizing vasculitis
49
What is the treatment for purpura hemorrhagica?
corticosteroids and supportive care +/- antibiotics
50
What are the signs of purpura hemorrhagica?
edema?
51
When does purpura hemorrhagica occur in horses that had strangles?
around 2wks later?
52
IN horses that get bastard tstrangles, when does it become apparent? where does it usually occur?
months to years later
| most commonly lung, mesentery, liver, spleen, kidney, brain
53
What is the mechanism of myositis with strangles horse?
immune mediated
| muscle infarctions and rhabdomyolysis with progressive atrophy
54
HOw do you prevent strangles?
1. after natural infection, 75% of horses not reinfected within 5 years
2. isolate all arrivals for 2 weeks
3. immediately isolate affect horses
4. check rectal temp during outbreak
5. nasal swab/washes for culture/PCR
6. beware of water troughs
7. vaccination
55
What is the most commonly used vaccination fo strangles?
pinnacle live intranasal vaccine
56
Why should you not use vaccination in animals with high titers?
can cause vasculitis?
57
The influenza virus is in what group?
orthomyxovirus group
58
What are the types of influenza in horses?
H7N7
| H3N8
59
What is the incubation time of influenza?
1-3d
60
What animals get influenza?
outbreaks in young horses 1-3years, often at race tracks
61
What is the pathogenesis of influenza?
1. neruaminidase alters efficiency of mucociliary apparatus
2. virus attach via hemagglutinin antigens to sugar goups on surface of resp tract epithelial cells
3. viral replication followed by cell necrosis and desquamation
4. inflammation leads to massive edema and lymphocyte infiltration
5. recovery of normal epithelal architecture can take more than 6 weeks
62
Why should horses be rested after influenza infection?
because recovery of normal epithelial architecutre can take more than 6 weeks
63
What are the clinical signs of influenza?
1. dry harsh cough 1-3 weeks
2. biphasic pyrexia for 4-5 days
3. in some horses: myalgia, myositis, limb edema and thus reluctant to move--immune mediated
4. in young foals influenza is SEVERE--viral pneumonia, possible death in 48hr
64
How is influenza diagnosed?
detection of virus--nasopharyngeal swabs
(viral isolation, PCR, ELISA--nucleoprotein antigen)
seroconversion
65
What is treatment for influenza?
symptomatic
| secondary bacterial pneumonia and pleuropneumonia are potential complications
66
How is influenza controlled?
1. vaccination (not that effective). there are different types. Recombitek e.g.
67
What herpes viruses (rhinopneumonitis) cause resp form of dz?
EHV-1, EHV-4
68
What is the incubation period of herpesvirus?
3-7 days but has latent state!!
69
What are the signs of herpes virus infection?
URT edema, hyperemia, petechial hemorrhaeg
70
What does EHV-1 cause that EHV-4 does not?
1. neonatal death or weak foals with interstitial pneumonia, hypoplasia of thymus and spleen
2. abortions--infection several months before--serology not useful (imp!)
3. myeloencephalopathy (neural)
71
What are the respiratory signs of herpesvirus EHV-1, 4
1. cannot distinguish EHV-1, 4
2. first year of life, usually soon after entry into training
sudden onset of fever, (often biphasic)
3. serous to mucopurulent nasal discharge
4. coughing NOT dependable!
72
What are signs on farm of an EHV infection?
abortions
young horses with nasal discharge?
maybe neuro case
over a period of time
73
When do animals usually get the resp form of EHV?
first year of life
usually mild disease
nasal discharge, fever
74
does vaccination prevent the neurologic form of EHV?
NO
75
DOes vaccination prevent abortion caused by EHV-4?
debated
76
Can horses vaccinated against EHV still become infected/shed virus?
yes. but may reduce clinical signs
77
What EHV virus besides 1 and 4 can cause resp disease in foals?
EHV-2
| and may play a role in R. equi pneumoniae
78
What is the half life of maternal antibodies for EHV?
1 month
79
Is the titer for EHV vaccination long lived or short lived?
short lived
80
What is the equine viral arteritis vvirus?
enveloped RNA virus of arterivirus
81
Are most infections of equine viral arteritis clinical or subclinical?
usually inapparent or subclinical (IMPORTANT)
82
What does infection of equine viral arteritis cause?
resp signs and abortion
83
What is the seroprevalance of equine viral arteritis in standardbreds?
as high as 80%
84
What are the clinical signs of equine viral arteritis
often subclinical but can be severe disease, death
pyrexia, anorexia, depression
edema scrotum, ventrum, limbs, periocular
serous nasal discharge, dyspnea and cough
conjunctivitis and lacrimation
85
WHat is the mechanism of edema with equine viral arteritis
arteritis
86
What are the signs of equine viral arteritis in foals.?
severe resp signs
high mortality
fever, leukopenia, thrombocytopenia
87
What are the signs equine viral arteritis on necropsy in neonatal foals?
1. interstitial pneumonia
| 2. lymphocytic arteritis and periarteritis and renal tubular necrosis
88
When do mares abort with equine viral arteritis?
abort LATE in gestation, 3-8 weeks after infection
89
Why are stallions important in equine viral arteritis transmission
because can transmit infection venereally AND in semen (even frozen semen!!)
often these stallions have no signs
90
What is the EVA cycle?
1. horses infected by resp route may show signs in 3-4 days
2. infected mare may transmit to stallion (or recover)
3. infected stallions shed virus for 1-3 weeks (may recover)
4. 30% of stallions recover and shed long term in semen alone
5. shedding stallion infects mare
6. mare may show clinical signs, shed from nose and mouth and may abort 10-17d later
91
What is the most common cause of bacterial pneumonia?
streptococcus zooepidemicus
92
Where is strep zooepidemicus found in normal horses?
in pharynx
93
What is a less common cause of bacterial pneumonia?
strep equi
94
What bacteria can complicate strep pneumonia?
gram negative bacteria
1. PASTEURELLA
2. e coli
3. enterobactrer
4. klebsiella
5. pseudomonas
95
What anaerobes can complicate arobic bacterial pneumonia?
1. bacteroides
| 2. clostridium
96
Why do you start with bnroad spectum antibiotics with bacterial pneumonia?
because often mixed infection of gram +, gram - and anaerobes
97
What are the clinical signs of acute bacterial pneumonia?
1. fever, may be intermittent
2. tachypnea
3. nasal discharge
4. coughing
5. exercise intolerance
98
What are the clinical signs of chronic bacterial pneumonia?
1. fever, tachypnea, nasal discharge, coughing, exercise intolerance
2. weight loss
3. +/- decreased appetite
99
When clinical signs indicate pulmonary dysfunction, you must differentiate between infectious and non-infectious! What tests must be performed?
transtracheal wash and culture
100
What are causes of infectious pulmonary dysfunction?
1. BACTERIAL
2. viral *usually URT
3. fungal
4. aspergillosis (oft follows GI dz)
5. parasitic--parascaris equrum, dictyocaulus
101
What are causes of non-infectious pulmonary dysfunction
1. recurrent airway obstruction
2. small airway inflammatory disease
3. neoplasia (lymphosare coma, metastatic--renal/gastric carcinoma, melanoma)
102
What is the diagnstic approach for pulmonary dysunction LRT dz
1. physical examination
2. auscultation
3. clinical pathology
4. tracheobronchial aspirate
5. thoracic radiographs
6. ultasonography
103
When expiratory sounds are louder than inspiratory sounds what should you think of?
lower airway disease
104
What can be heard with ascultation with lower airway disease?
increased harshness/intensity of expiratory sounds
2. when expiratory sounds loudher than inspiratory sounds
3. end inspiratory crackles (transient atelectasis, increased secretion)
4. expiratory wheezes--inflamed airways, narrowed by thick secretions
5. if pleuropneumonia then rubbing sounds, quiet ventral thorax (sub-pleural abscessation, pleural effusion--horizontal line demonstrated by ausculatation, percusion)
105
What is seen on CBC and biochemistry with lung dysfunction?
leukocytosis (neutrophilia +/- bands)
hyperfibrinogenemia
increased total plasma proteins in chronic cases due to chronic antigenic stimulation
106
What is seen on tracheal wash with bacterial infection?
1. degenrated neutrophils
2. precipitation
3. necrotic material
4. damaged epithelial cells
107
What should be performed on tracheobronchial apsirate?
1. cytology
2. culture
3. gram stains
108
What is seen on thoracic radiographs with pulmonary dz bacterial pneumonia
1. opacity in anteriovental thorax
2. horiztonal line across ventral thorax if pleural effusion
3. large cavitary lesions with horizontal line
4. abscesses-anaerobic gas forming organisms
109
What is the most sensitive tool to evaluate the pleural space?
ultrasonography
110
How do you detect pleural effusion?
1. detect by
a. auscultation
b. percussion
c. radiography
d. ultasounography
2. can be aspirated and drained
111
Why should you preferntially culture tracheal aspirate over pleural aspirate?
because tracheal aspirate often yields pathoenic organisms while pleural aspirate may not
112
What is the pathophysiology of bacterial pneumonia?
1. compromize of pulmonary defense mechanisms (mucociliary clearance, phagocytic cells, cellular and humoral immune systems)
2. inhalation, aspiration (adults), hematogenous spread (neonates common) of bacteria
113
What is the treatment for bacterial pneumonia?
* based on culture/sensitivity*
1. penicillin
2. ampicillin
3. aminoglycosides
4. second and third gen cephalosporins
5. TMS
6. fluoroquinolones
7. metronidazole
8. rifampin
114
What anaerobe does penicillin no tget?
bacteroides?
115
What is the most common combination of antimicrobials for bacterial pneumonia?
penicillin and aminoglycosides may had metronizdazole if suspect anaerobes?
116
Why is TMS not very good for bacterial pneumonia?
at the site of infection there is high PABA etc
117
What is equine multinodular pulmonary fibrosis?
interstitial lung disease and fibrosis
caused by gama herpesvirus EHV-5
numerous coalescing nodules of fibrosis
Lesions confined to alveolar parenchyma (mixed inflam, preserved alveolar like architecture
118
What the cause of equine multinodular pulmonary fibrosis
gamma herpesvirus EHV-5
119
How is equine multinodular pulmonary fibosis treated?
1. supportive (antibiotics, antivirals NSADs)
| 2. corticosteroids to reduce inflammation causing fibrosis!!
120
What is the prognosis for equine multinodular pulmonary fibrosis?
poor. 76% die or euthanized
121
What are immunological considerations in foal pneumonia?
1. failure of passive transfer
2. maternal antibodies
3. immunologic system maturation
122
What is the most common agent of peumonia in adult and foal pneumonia?
strep equi zooepidemicus
123
What are causes of septicemia/pneumonia?
actinobacillus equuli
| e. coli
124
If you see a foal with pneumonia, diarrhea, what should you think unless proven otherwise?
septicemia
125
Are anaerobe common or rare in foals?
rare
126
In nenonatal foals, bacterial pneumonia is a frequent manifestation of what?
NEONATAL SEPTICEMIA
127
What is the greatest cause of mrobidity and mortality in foals less than 1 month of age?
bacterial pneumonia
128
What are the reasons that neonatal foals get bacterial pneumonias?
1. decreased cells in BAL (until 3-6wk)
2. macrophage predominant cell (in adult is same)
3. transfer of maternal antibodies
4. waning of maternal antibodies
5. different immune response compared to adults
129
What is seen on BAL with undifferentiated bacterial pneumonia?
neutrophils +/- cocci
130
What is the diangostic approach for neonatal foals?
1. clinical signs may be few but tachypnea and increased resp effort
2. thoracic radiographs
3. arteiral blood gas analysisi
4. blood cultures
131
Why must you be careful with tracheobronchial aspirates and BAL in septic foal?
can be dangerous in compromized septic foal
132
What is the diagnostic method for older foals?
1. tracheobronchial aspirates
2. thoracic radiographs
3. thoracic ultasonography
133
Who gets undifferentiated resp tract dz?
foals 4-5 months old
134
What is the morbiditiy in undifferentiated resp tract dz foals?
up to 80-90%
135
what are the causes of undifferentiated resp tract dz of foals?
1. strep zooepidemicus most prominent
2. staph epidermidis
3. r. equi
4. viruses?
136
What are the clinical signs of undifferentated resp tract dz?
1. crackles
2. wheezes
3. mucopurulent nasal discharge
4. cough and tachypnea
137
what is seen on radiograph with undifferentiated resp tract dz?
mild bronchointerstitial pattern
138
What is seen on BAL with unidfferentiated resp tract dz of foals?
increased neutrophils +/- intracellular cocci
139
What is treatment for undifferentiated resp tract dz of foals?
strep zoo senisitive to beta lactams (penicillin, ampiciling, TMS)
140
What is the prognosis of undifferentiated resp tract dz of foals?
30% relapse rate
| long term prognosis hard to assess
141
What is the mean age of rhodococcus equi pneumonia?
2 months (1-6 months)
142
What are the clinical signs of rhodococcus equi pneumonia?
1. fever, crackles, wheezes, tachypnea
2. +/- mucopurulent nasal discharge
3. +/- cough
4. +/- resp distress
143
What is the most devastating cause of pneumonia in foals between 3wk to 5 months?
R. equi pneumonia
144
What can predispose to R. equi pneumonia?
overcrowding and dusty conditions
145
What is the major source of contamination of soil with R. equi
FOAL FECES (question he may ask)
146
What is the major route of infection for R. equi?
inhalation of dust and virulent R. equi
147
When are foals infected with R. equi? when do they show signs?
they are infected at a very early age but signs usually evident 2-5 months old
148
What are the features of R> equi?
1. gram +
2. facultative intracellular
3. lives and multiplies inside alveolar macrophages
4. pathogenic R. equi contains plasmids encoding for specific virulence associated proteins (VAP-A)
149
What gene is required for virulene of R. equi?
VAP-A
150
What are the clinical manifestations of R. equi?
chronic suppurative bronchopneumonia with extensive abscessation
151
Why is early clinical diagnosis of R. equi difficult?
slow spread of lung infection
| foals can compensate for loss of lung parenchyma!!
152
What are the early signs of R. equi pneumonia?
often only mild fever or slight increase in resp rate
153
What is the subacute form of R. equi? is it common?
acute resp distress and high fever. Not common
154
What are extrapulmonary manifestations of R. equi?
1. intestinal lesions
2. polysynovitis
3. uveitis, anemia, thrombocytopenia
155
What are intestinal lesions caused by R. equi?
1. multifocal ulcerative enterocolitis and typhlitis
2. in 50% of foals with pneumonia
3. most don't show GI signs!!!!!
4. weight loss, colic, diarrhea
156
Do most foals with R. equi show GI signs?
no, most don't, but 50% of those with pneumonia have lesions.
157
How common is polysynovitis in foals with R. equi pneumonia?
1/3
158
Are foals with polysynovitis due to R. equi infection lame?
no! can allow to differentiate from bacterial synovitis
159
What is the mechanism of polysynovitis in foals with R. equi?
immune complex deposition
| NON-septic (mononuclear)
160
What are the most common joints affected by polysynovitis in foals with R. equi?
tibiotarsal and stifle
161
How do you differentiate polysynovitis due to R. equi and bacterial joint infection in foals?
with bacterial infection they are painful, with r. equi polysynovitis they are not
162
How is R. equi diagnosed?
1. culture, PCR (VAP-A) + cytology of trachchial aspirate
2. CBC
3. serology
4. radiography
5. ultrasonography
163
Why is isolation of R equi alone from a tracheobronchial wash not sufficient for diagnosis of R equi pneumonia?
because R. equi can be prevalent on farms and some foals may have without being sick
164
What is seen on CBC and fibrinogen with R. equi?
1. neutrophilic leukocytosis
| 2. hyperfibrinogenemia
165
What is seen on radiographs with R. equi pneumonia?
1. prominent alveolar pattern, regional consolidation
| +/- hilar lesions (abscesses)
166
What do you see with ultrasonography with R. equi pneumonia?
abscess at periphery of the lungs
167
How do you differentiate R. equi pneumonia vs baterial pneumonia?
big abcesses with R. equi vs cranioventral consolidation with bacterial pneumonia?
168
Why is serology not very useful for R. equi pneumonia diagnosis?
widespread exposure
169
How is R. equi pneumonia diagnosed?
1. antimicrobials 6-8wks
2. erythromycin + rifampin
3. azithromycin and clarithromycin
170
Why do we now use more azithromycin and clarithromycin instead of erythromycin and rifampin for treatment of R. equi?
E + R can cause diarrhea, hyperthermia, tachypnea, increased liver enzymes and clostriidum difficile enterocolitis in dams
171
What are benefits of using azithromycina nd clarithromycin in R. equi pneumonia?
1. enhanced oral bioabilability
2. prolonged half lives
3. high concentratrions in bronchoalveolar cells and pulmonary epithelial lining fluid
172
What is the pattern of pneumonia with acute resp distress syndrome?
bronchointerstitial pneumonia
173
What is acute resp distress syndrome characterized by?
severe resp distress
174
What is the causative organisms of acute resp distress snydrome?
unknown
175
What animals are affected by acute resp distress syndrome?
foals 1-7 months
176
What are clinical signs of acute resp distress syndrome?
tachypnea, increased resp effort, cyanosis
| hypoxemia, hypercapnia, resp acidosis
177
What is seen on radiography with foals with acute resp distress syndrome?
interstitial for bronchointerstitial pattern
178
What is treatment for acute resp distress syndrome? why can this be an issue?
They do NOT respond to antibiotics
use oxygen therapy, bronchodilators, and CORTICOSTEROIDS
but corticosteroids suppress immune system! so if you are wrong then could kill foal faster?
179
What is the prognosis for acute resp distress syndrome?
guarded for life and future athletic activity
180
What kills foals with acute resp distress syndrome?
overwhelming inflammatory response
