PATHOLOGY - Equine Lower Respiratory Disease Flashcards
(158 cards)
1
Q
What are general signs of respiratory disease in horses?
A
Cough
Nasal discharge
Altered respiratory rate, rhythm and/or effort
Respiratory noise
Altered airflow at the nostrils
Poor performance
Weight loss
2
Q
Which questions can be useful to ask when gathering a history if you suspect respiratory disease?
A
Vaccinations/deworming?
Duration of the clinical signs?
Seasonality of the clinical signs?
Has any poor performance been sudden or progressive?
Any recent travel?
Are any other horses affected?
Ask questions about the enviornment the horse lives in?
3
Q
What should you do during subjective observation of a horse with suspected respiratory disease?
A
Assess the environment such as ventilation, bedding and forage
Assess respiratory rate, rhythm and effort
4
Q
What is the normal respiratory rate for a horse?
A
8 - 16 breaths per minute
5
Q
What can be indicative of increased respiratory effort in horses?
A
Biphasic breathing pattern noticable at rest
6
Q
What are three key signs of dyspnoea in horses?
A
Nostril flaring
Increased abdominal effort
Noise on inhalation/exhalation
7
Q
What is indicated by rapid, deep breathing in the horse?
A
Rapid, deep breathing indicates respiratory distress
8
Q
What is indicated by rapid, shallow breathing in the horse?
A
Rapid, shallow breathing can indicate pain, particularly pleural pain
9
Q
What is indicated by slow, deep breathing in the horse?
A
Slow, deep breathing can indicate an underlying disease process such as equine asthma
10
Q
Which factors should you assess during the clinical exam of the head and neck in a horse with suspected respiratory disease?
A
Assess for nasal discharge
Assess airflow at the nostrils
Palpate the lymph nodes
Assess facial symmetry
Assess for ocular discharge
Palpate the trachea
Auscultate the trachea
Listen for any upper respiratory noise
11
Q
Which lymph nodes should you palpate on a horse?
A
Submandibular lymph nodes
Retropharyngeal lymph nodes
12
Q
What is a tracheal pinch test?
A
If you pinch the trachea and this elicits a cough, this can be indicative of tracheal sensitivity
13
Q
What is indicated by unilateral nasal discharge in horses?
A
Unilateral nasal discharge in horses is typically associated with disease of the sinuses or nasal passages
14
Q
What is indicated by bilateral nasal discharge in horses?
A
Bilateral nasal discharge in horses is typically associated with disease of the lower respiratory tract
15
Q
What are the different classifications of nasal discharge?
A
Serous
Mucoid
Purulent
Sanguineous
Epistaxis
Food containing
16
Q
What can be indicated by epistaxis at rest in horses?
A
Guttural pouch mycosis
Ethmoidal haematoma
Nasal polyp
17
Q
What can be indicated by epistaxis during exercise?
A
Exercise induced pulmonary haemorrhage
18
Q
Why might you get epistaxis following nasogastric intubation in the horse?
A
Nasogastric intubation can cause ethmoidal trauma and haemorrhage
19
Q
What are the boudaries for equine thoracic auscultation?
A
20
Q
What can be indicated by wheezes at the end of exhalation on equine thoracic auscultation?
A
Wheezes at the end of exhalation can indicate equine asthma
21
Q
What can be indicated by pleural friction rubs on equine thoracic auscultation?
Pleural friction rubs sound like sandpaper
A
Pleural friction rubs can indicate pleuritis
22
Q
What can be indicated by the absence of lung sounds on equine thoracic auscultation?
A
The absence of lung sounds can indicate pleural effusion or pneumothorax
23
Q
What is a rebreathing exam?
A
A rebreathing exam involves placing a bag over the horse’s nose and mouth for one minute, which allows for the build-up of carbon dioxide stimulating the horse to take deeper breaths. It should then be easier to detect lung sounds on thoracic auscultation
24
Q
(T/F) Coughing is normal during and following a rebreathing exam?
A
FALSE. Coughing is abnormal during and following a rebreathing exam
25
When should avoid doing a rebreathing exam?
Avoid doing a rebreathing exam if the horse is in respiratory distress
26
Which diagnostic tests can you do to investigate respiratory disease in a horse?
Endoscopy
Infectious disease sampling
Lower respiratory sampling and cytology
Ultrasound
Radiography
Thoracocentesis
27
How do you grade tracheal secretions seen during endoscopy?
Grade 0: No visible mucus
Grade 1: Single to multiple small blobs of mucus
Grade 2: Larger but non-coalescing blobs of mucus
Grade 3: Coalescing or stream forming mucus
Grade 4: Pool forming mucus
Grade 5: Profuse mucus
28
How should the guttural pouches appear on endoscopy?
The guttural pouches should appear transparent
| There may be areas of black in horses with a dark coat due to melanocyte
29
When should you not assess the larynx during endoscopy?
If the horse has been sedated, as this can impede results
30
Which sampling method do you use for infectious disease sampling?
Nasopharangeal swab
31
Which sampling methods do you use for lower respiratory sampling and cytology?
Tracheal wash
Bronchoalveolar lavage
32
What is the main benefit of carrying out a tracheal wash?
Because respiratory secretions are brought up from the lungs via mucocilliary clearance, the sample obtained from the tracheal wash will be representative of all areas of the lungs
33
What are the two methods that can be used to carry out a tracheal wash?
Trans-tracheal (percutaneous) wash
Trans-endoscopic tracheal wash
34
How do you carry out a trans-tracheal (percutaneous) wash?
1. Sedate your patient
2. Palpate the ventral midline of the neck and carry out sterile prep instill local anaesthetic onto the area
4. Carry out a small incision at the level of the tracheal 'sump' between two tracheal rings
5. Insert the introduction catheter through the incision and into the trachea
6. Thread the long collection catheter through the introduction catheter and when it is correctly positioned, slowly infuse 20ml of sterile saline and then start aspirating slowly
35
What kind of tube do you submit a tracheal wash sample in?
EDTA tube
36
What are the benefits of using an opioid in combination with the sedative drug when carrying out a trans-tracheal (percutaneous) wash?
Opioids are antitussive and thus will reduce coughing which could potentially displace the tracheal puddle, making it more difficult to aspirate
37
Why can you use a trans-tracheal (percutaneous) sample for both cytology and culture?
A trans-tracheal (percutanous) wash is done aseptically and thus there is minimal risk of contamination
38
Which two types of catheter can be used for trans-endoscopic tracheal wash?
Single lumen catheter
Triple lumen catheter
39
Which catheter should you use for a trans-endoscopic tracheal wash if you want to send the sample for cytology and culture?
Triple lumen catheter to reduce the risk of contamination
40
Which bacteria can commonly contaminate tracheal wash samples?
Pseudomonas
41
Which two cell types should mainly be found in a tracheal wash sample?
Macrophages
Lymphocytes
42
What is the normal percentage of neutrophils present in a tracheal wash sample on cytology?
Less than 20%
43
(T/F) Travelling or housed horses can briefly have up to 50% neutrophils in a tracheal wash sample
TRUE. However these levels will be expected to decrease with no clinical signs
44
Which two methods can be used to carry out bronchoalveolar lavage?
Blind bronchoalveolar lavage
Endoscopic bronchoalveolar lavage
45
What information can be provided by blind bronchoalveolar lavage?
Bronchoalveolar lavage is often done blind and often samples from the right dorsocaudal lobe. This will provide information if there is a diffuse pathology, however there is a risk of missing more focal pathology
46
What is the main sign of a successful bronchoalveolar lavage?
If you have managed to aspirate surfactant you know you have samples the distal bronchioles and alveoli
47
(T/F) Bronchoalveolar lavage samples are appropriate for both cytology and culture
FALSE. Bronchoalveolar lavage is only appropriate for collecting cytology samples
48
Which two cell types should mainly be found in a bronchoalveolar lavage sample?
Macrophages
Lymphocytes
49
What is the normal percentage of neutrophils present in a bronchoalveolar lavage sample on cytology?
Less than 5%
50
What are three key indicators of infectious respiratory disease in horses?
Pyrexia
Enlarged lymph nodes
Other horses affected
51
What is the most common bacteria that causes infectious respiratory disease in horses?
Streptococcus equi
52
Which disease is caused by streptococcis equi?
Strangles
53
(T/F) Streptococcus equi is a gram positive bacteria
TRUE.
54
Which signalement is particulalrly prone to streptococcus equi infection?
Young, immunologically naive horses
55
Describe the pathogenesis of acute streptococcus equi infection
Streptococcus equi enters the body via the mouth or nose causing pyrexia and pharangitis, and invades the upper respiratory tract lymph nodes causing lymph node abscesses
56
Why is acute streptococcus equi infection not often treated with antibiotics?
Acute streptococcus equi is not often treated with antibiotics and antibiotics cannot penetrate the abscesses
57
What is the prognosis for a horse with acute streptococcus equi infection?
Generally the abscesses will burst and the horse will clear the infection and make a full recovery
58
Describe the pathogenesis of carrier/chronic streptococcus equi infection
Streptococcus equi enters the body via the mouth or nose causing pyrexia and pharangitis, and invades the upper respiratory tract lymph nodes causing lymph node abscesses. When the abscesses burst, some of the pus and bacteria can enter the guttural pouches and not be fully cleared by the body, resulting in a carrier/chronic infection
59
Which three methods can you use to diagnose a streptococcus equi infection?
Nasopharangeal swab followed by culture and PCR
Aspiration the lymph node abscesses followed by culture and PCR
Guttural pouch lavage followed by culture and PCR
60
What are the three most common viruses that causes infectious respiratory disease in horses?
Equine influenza A
Equine herpes virus 1
Equine herpes virus 4
61
Which serotype of equine influenza A most commonly causes equine influenza?
H3N8 serotype
62
Describe the pathogenesis of equine influenza A
The neuraminidase breaks down the mucociliary carpet, allowing for the heamagglutinin to allow for viral attachment to the host respiratory epithelium, causing cellular necrosis and desquamation. This results in inflammation, oedema and exposes irritant receptors resulting in excess mucus production
63
How long does it take for the normal respiratory architecture to recover from an equine influenza A infection?
6 weeks
64
What are the clinical signs of equine influenza?
Pyrexia *(39 to 41°C)*
Harsh cough
Serous or mucopurulent nasal discharge
Maybe pharyngitis and tracheitis
Swollen lymph nodes
Anorexia
Depression
65
Which methods can you use to diagnose influenza A?
Nasopharyngeal swab followed by viral culture/isolation, real time PCR and ELISA
66
What can you do to treat equine influenza?
Isolate
Hydration
NSAIDs for pyrexia
Minimise stress
Rest
67
How long should a horse be rested for with equine influenza?
The rule of thumb is for every °C above normal, the horse should be rested for 1 week
68
How can you prevent equine influenza?
Adequate ventilation
Biosecurity
Vaccinations
69
Describe the British Horseracing Authority (BHA) vaccination protocol
First vaccine (influenza and tetanus), 21 to 60 days later do the second vaccine (influenza and tetanus), 120 to 180 days later do the third vaccine (infuenza). Do influenza boosters every 6 months and tetatnus boosters every 2 to 3 years
70
What are the two most significant effects of equine herpes virus 1 and 4 infections?
Abortion
Equine herpes 1 myeloencephalopathy
71
What is equine asthma?
Equine asthma is a general term used to describe all non-infectious lower respiratory airway inflammation
72
What are the two classifications of equine asthma?
Mild/moderate equine asthma
Severe equine asthma
73
What is the difference between mild/moderate and severe equine asthma?
Mild/moderate equine asthma can be seen in all ages and is distinguished from severe equine asthma by a lack of increased respiratory effort at rest
74
What is the most likely cause of mild/moderate equine asthma?
Mild/moderate equine asthma is most likely caused by a hypersensitivity to airborne organic dust
75
What are the clinical signs of mild/moderate equine asthma?
Cough
Exercise intolerance
76
How do you diagnose mild/moderate equine asthma?
History
Clinical signs
Endoscopy
Bronchoalveolar lavage and cytology
77
What is a sign of mild/moderate equine asthma on endoscopy?
There may be mucus accumulation in the trachea
78
What would you find on cytology of a bronchoalveolar lavage in a horse with mild/moderate equine asthma?
Neutrophils (5 - 20%)
± Eosinophils
± Mast cells
79
What is the prognosis for mild/moderate equine asthma?
Mild/moderate equine asthma should be short duration and can resolve spontaneously or with treatment, with a limited risk of recurrence
80
What is the most likely cause of severe equine asthma?
Severe equine asthma is most likely caused by a hypersensitivity to airborne organic dust which results in a neutrophil influx into the airways, mucus accumulation, bronchospasm resulting in airway obstruction, airway hypersensitivity and eventually fibrosis
81
What are the four main forms of airborne organic dust that can cause severe equine asthma?
Bedding
Hay
Fungal spores
Bacterial endotoxins
82
What age group tend to present with severe equine asthma?
Horses over 7 years old
83
What are the potential clinical signs of severe equine asthma?
Cough
Mucoid nasal discharge
Increased respiratory effort at rest
Exercise intolerance
Nostril flaring
Tachypnoea
84
How do you diagnose severe equine asthma?
History
Clinical signs
Endoscopy
Tracheal wash and cytology
Bronchoalveolar lavage and cytology
Determine if the asthma is reversible
85
What might you hear on thoracic auscultation that could be indicative of severe equine asthma?
End expiratory wheezes
End inspiratory crackles
86
What is a sign of severe equine asthma on endoscopy?
Mucus accumulation (grade 3 to 5)
87
What would you find on cytology of a tracheal wash in a horse with severe equine asthma?
Neutrophils (above 50%)
88
What would you find on cytology of a bronchoalveolar lavage in a horse with severe equine asthma?
Neutrophilia (over 25%)
89
How can you rapidly determine if the asthma is reversible?
To rapidly determine if the asthma is reversible, administer buscopan to see if the horse's condition improves in response to the bronchodilation
90
What environmental changes should be made to manage severe equine asthma?
24 hour turnout *(however this is often unrealistic)*
Low dust bedding
Low dust feed
Good ventilation
Avoid deep litter bedding
Groom horses outside
Don't muck out with horses in the stable
Don't store forage/bedding near the stables
Don't position the muck heap next to the stables
91
What can be used as low dust bedding?
Dust extracted shavings
92
What can be used as low dust feed?
Haylage
Soaked hay
93
How long should you soak hay for?
30 minutes to 2 hours
94
Why is it important to avoid deep litter bedding?
Deep litter bedding allows for the accumulation of ammonia and faeces which contain bacterial endotoxins which can contribute to severe equine asthma
95
Which drug classification can you use to control the inflammation associated with severe equine asthma?
Corticosteroids
96
Which two systemic corticosteroids can be used in the treatment of severe equine asthma?
Dexamethasone
Prednisolone
97
What is the main risk of using systemic corticosteroids in the treatment of severe equine asthma?
Systemic corticosteroids can increase the risk of laminitis
98
Which three inhalational corticosteroids can be used in the treatment of severe equine asthma?
Ciclesonide
Fluticasone
Beclomethasone
99
Which drug classification can you use to control the airway obstruction associated with severe equine asthma?
Bronchodilators
100
Why should bronchodilators not be used alone in managing severe equine asthma?
Bronchodilators do not address the underlying inflammation and thus should be combined with anti-inflammatory drugs and environmental management
101
Which two drug classifications can be used as bronchodilators?
β2-adrenergic agonists
Anticholinergic drugs
102
Which systemic β2-adrenergic agonist can be used in the treatment of severe equine asthma?
Clenbuterol
103
What are the three key side effects of clenbuterol in horses?
Sweating
Mild colic
Inteferes with parturition
104
Which inhalational β2-adrenergic agonists can be used in the treatment of severe equine asthma?
Salbutamol
Salmeterol
105
When is salbutamol indicated in the treatment of severe equine asthma?
Salbutamol is used as an emergency treatment
106
When is salmeterol indicated in the treatment of severe equine asthma?
Salmeterol is used for more long term control of severe equine asthma
107
Why should β2 specific adrenergic agonists be used intermittently?
β2 specific adrenergic agonists should be used intermittently to avoid tolerance through internalisation of the β2 receptors in response to excessive stimulation
108
Which two anticholinergic drugs can be used in the treatment of severe equine asthma?
Atropine
Buscopan
109
When is atropine indicated in the treatment of severe equine asthma?
Atropine is used as an emergency treatment when a horse is in severe respiratory distress
110
When is buscopan indicated in the treatment of severe equine asthma?
Buscopan is used as a diagnostic to determine if the asthma is reversible with bronchodilation
111
What is the prognosis for severe equine asthma?
Severe equine asthma has a long duration and is recurrent
112
What is pasture associated equine asthma?
Pasture associated equine asthma has an almost identical presentation to severe equine asthma except it is associated with horses on pasture rather than stabled horses
113
What can exacerbate pasture associated equine asthma?
Hot, humid weather
114
What is the signalement for exercise induced pulmonary haemorrhage (EIPH)?
Exercise induced pulmonary haemorrhage (EIPH) is most commonly seen in racehorses following strenuous exercise
115
What are the five possible clinical signs of exercise induced pulmonary haemorrhage (EIPH)?
Asymptomatic
Epistaxis post exercise
Repeated swallowing post exercide
Poor performance
Prolonged recovery post exercise
116
How do you diagnose exercise induced pulmonary haemorrhage (EIPH)?
Endoscopy
117
What can be key signs of exercise induced pulmonary cytology on bronchoalveolar lavage cytology?
Erythrocytes
Haemosiderophages
± Neutrophils
118
How do you treat exercise induced pulmonary haemorrhage (EIPH)?
Rest the horse for 2 to 4 weeks
119
What can be used to prevent equine induced pulmonary haemorrhage?
Altered training methods.
Prophylactic furosemide
| However furosemide cannot be used before racing in the UK
120
What is the signalement for equine multinodular pulmonary fibrosis?
Older horses
121
How do you differentiate equine multinodular pulmonary fibrosis from severe equine asthma?
To differentiate equine multinodular pulmonary fibrosis from severe equine asthma, administer buscopan to determine if the clinical signs are reversible or not. If the signs are **not** reversible, this is more likely to be equine multinodular pulmonary fibrosis
122
Which species of trichostrongloidea causes lungworm in horses?
Dictyocaulus arnfieldi
123
What is an important history question to ask if you suspect a dictylocaulus arnfieldi infection?
Ask if the horse has been in contact with any donkeys or mules as they are asymptomatic reservoirs of dictyocaulus arnfieldi
124
How do you treat dictyocaulus arnfieldi in horses?
If you suspect dictyocaulus arnfieldi from the history and clinical signs, treat the horse with ivermectin or moxidectin
125
What is the most common infectious agent that causes bronchopneumonia in horses?
Bacteria
126
Descripe the pathogenesis of bacterial pneumonia
Bacteria in the upper respiratory tract can contaminate the lower respiratory tract, which usually is not a problem unless there is an overwhelming bacterial infection or impairment of the host defences, which will then result in bacterial pneumonia
127
What are the risk factors for bacterial pneumonia?
Aspiration
Choke
Laryngeal/pharyngeal dysfunction
Transport
Exercise
Viral infection
General anaesthetic
Environment
128
What is choke in horses and how can it cause bacterial pneumonia?
Choke in horses refers to oesophageal obstruction which can cause aspiration and bacterial pneumonia
129
How does laryngeal/pharyngeal dysfunction cause bacterial pneumonia?
Laryngeal/pharyngeal dysfunction increases the risk of aspiration which can result in bacterial pneumonia
130
How can transport cause bacterial pneumonia?
Transport causes stress which reduces the horse's immune system and horses will typically have their head elevated during transport which impairs mucocilliary clearance, which further impairs the immune system which can result in bacterial pneumonia
131
How can exercise cause bacterial pneumonia?
Exercise can result in aspiration of dirt etc and can comprimise the immune system which can cause bacterial pneumonia
132
What are three of the most common cause of bacterial pneumonia in foals?
Aspiration of milk
Streptococcus zooepidemicus infection
Rhodococcus equi infection
133
How do you treat rhodococcus equi in foals?
4 to 9 weeks of rifampin and a macrolide antibiotics
134
What is pleuropneumonia?
Pleuropneumonia is a severe manifestation of bronchopneumonia where the infection has extended into the pleural cavity
135
What are the clinical signs of bacterial pneumonia?
Pyrexia
Soft cough
Inappetence
Exercise intolerance
Mucopurulent nasal discharge
Tachypnoea
Hypopnoea
Respiratory distress
136
What can you hear on auscultation in a horse with bacterial bronchopneumonia?
Increased inspiratory noise with ventral crackles and wheezes
137
What is a key clinical sign of bacterial pleuropneumonia on auscultation?
Reduced ventral lung sounds indicative of a pleural effusion
138
How do you diagnose bacterial pneumonia?
History
Clinical signs
Haematology and Biochemistry
Endoscopy
Diagnostic imaging
Tracheal wash with cytology and culture
Thoracocentesis
139
What changes on haematology would be indicative of bacterial pneumonia?
Leukocytosis or in severe cases leukopenia
140
Which proteins would be elevated when there is bacterial pneumonia?
Fibrinogen
Serum amyloid A
Globulins
141
Which protein can be decreased when there is bacterial pneumonia?
Albumin
142
What is a sign of bacterial pneumonia on endoscopy?
Mucopurulent material in the trachea
143
What would you find on cytology of a tracheal wash in a horse with bacterial pneumonia?
Neutrophils (between 40 - 100%)
Degenerate neutrophils
Intracellular bacteria
144
What are some of the key signs of bacterial pneumonia on ultrasound?
Signs of lung consolidation
B lines
Abscesses
Pleural effusion
145
When would you do a thoracocentesis in a horse with bacterial pneumonia?
Do a thoracocentesis if there is an signs of pleural effusion to determine if it is a bacterial pleuropneumonia
146
How do treat bacterial pneumonia?
Administer first line antibiotics while you wait for the culture and sensitivity results. When the results come back pick an appropriate antibiotic for the bacteria that is present. Often antibiotics have to be given for 6 - 8 weeks
147
Which first line broad spectrum antibiotics are commonly used in horses?
Penicillin
Gentamicin
Metronidazole *(for anaerobic bacteria)*
148
Which first line broad spectrum antibiotic can be administered via nebulisation?
Gentamicin
149
What can be administered via nebulisation to break up mucus in bacterial pneumonia?
Saline
150
What supportive treatment can you provide horses with bacterial pneumonia?
NSAIDS
Bronchodilators
Intravenous fluid therapy
Provide good ventilation
Thoracocentesis or chest drain if there is pleural effusion
151
What can be administered to horses that have fibrin within their pleural space due to bacterial pleuropneumonia?
Tissue plasminogen activators (TPA) to lyse the fibrin and allow you to effectively drain the pus from the pleura using thoracocentesis/chest drain
152
When should horses begin to improve following antibiotics and supportive care for bacterial pneumonia?
Horses should begin to improve between 48 to 72 hours
153
How can you assess if a horse is responding to treatment for bacterial pneumonia?
Improvement in clinical signs
Decreasing fibrinogen and serum amyloid A levels
154
What are four of the main complications of bacterial pneumonia?
Abscesses
Pleural adhesions
Broncho-pleural fistulas
Laminitis
155
What is a broncho-pleural fistula?
A broncho-pleural fistula is an abnormal connection between the bronchi and the pleura
156
What is one of the most common causes of pleural effusion in horses?
| The most common cause is pleuropneumonia
Neoplasia
157
What is the most common neoplasm in the horse?
Mediastinal lymphoma
158
Which age range most commonly present with mediastinal lymphoma in horses?
5 to 10 years old
