Diagnostic imaging - the thorax Flashcards
The thorax
Describe your systematic approach to assessment of the thorax on radiographs ?
Systematic approach to the thorax
Thorax radiographs are assessed the same way every time no matter what the patient presents with - this prevents us missing pathologies.
Quality assessment
Heart - shape and size
Vessels - PA, PV, CVC and aorta
Lungs
Pleural space
Mediastinum - two things you can see and two things you can’t
‘Outside’ - skeleton, thoracic wall, diaphragm and abdomen
Describe two things you can see, and two you can’t within the cranial mediastinum on radiograph ?
Mediastinum
The structures within the cranial mediastinum are mostly soft tissue opacity so they efface (except trachea)
- trachea, oesophagus, blood vessels, lymph nodes
Two things you can see
trachea
cranial width
Two things you can’t see
- lymph nodes
- oesophagus
Define the mediastinum and location of the cranial mediastinum ?
Mediastinum
The mediastinum is all the organs along the middle of the thorax between the lungs.
The cranial mediastinum
- the cranial mediastinum extends from the first ribs to the cranial aspect of the heart.
Determine from radiographs if the cranial mediastinum has normal width on the VD view ?
Determine width of the cranial mediastinum
- measure only on VD view
- locate first ribs and cranial border of heart
- measure the width half way between these structures
Normal width of the cranial mediastinum is <2 times the width of the vertebra.
Recall the causes for wide cranial mediastinum from radiographs ?
Differential list wide cranial mediastinum
Tip; If the cranial mediastinum is wide, then go to the lateral view to work out what structure is abnormal.
Differential list
Pathology
- Lymphoma
- Thymoma
- Less common - other neoplasia (eg ectopic thyroid, cyts abscess, granuloma).
- not all mediastinal masses are neoplasia eg cyst are not uncommon
Non pathology
- fat
- brachycephalic dogs
- look on lateral view to check there is no mass.
Explan the normal apperance of the trachea in dogs of different body confirmation - identify the normal trachea on radiographs ?
The normal anatomy of the trachea upon radiograph in the dog
Trachea - gas
Dogs
The thoracic spine in the dog is straight so the angle with the trachea is constant
- in health runs parallel ventral to the spine
- on VD curves to the right slightly at the level of the heart (more obvious brachycephalic dogs)
- In barrel shaped dogs the trachea may run at a greater angle to the spine inhealth
- brachy dogs usually more parallel to the spine
Explain the normal appearance of the trachea in cats (being able to identify a normal trachea upon radiograph) ?
Cat radiograph trachea
Cats have a natural lordosis of the thoracic spine
- the caudal part of the trachea is at an angle to the spine
- cranially the trachea is parallel with the spine
What conditions could lead to an abnormal trachea diameter ?
Abnormal trachea
Trachea hypoplasia
Trachea collapse
Tracheal displacement
Identify this abnormality of the trachea and describe its aetiology ?
Tracheal hypoplasia
Identify
- measure trachea width ; compare to thoracic inlet ratio in health = 20% +/-3%
Tracheal hypoplasia
-generalised decrease in the width of the trachea
- part of brachiocephalic airway syndrome
- congenital
- clinical signs are more evident in puppies
Measured by the ratio of the tracheal width to the width of the thoracic inlet
Identify this abnormality of the trachea and how it would be diagnosed ?
Tracheal collapse
(Always presents CS chronic cough)
- middle aged older small breed dogs
- chondromalacia (softening of the tracheal rings)
How is it diagnosed
- endoscopy of the trachea is best
- Fluoroscopy is the best imaging method (black and white reveresed)
- radiographs are insensitive
On radiograph
tracheal collapse can be associated with dorsal tracheal membrane
CARE -not likely in large dogs, thus more likley to be oesophugus superimposition.
Determine from radiographs if there is tracheal displacementand the causes of it ?
Tracheal displacement differentials
Cranial ventral
- megaoesophagus
Cranial dorsal
- cranial mediastinal LNs
- mediastinal mass
- head is flexed during radiograph
- pleural effusion
At tracheal bifurcation
Ventral
- tracheaobronchial LN enlargement
Dorsal
- LA enlargement
Identify the thoracic lymph nodes and determine if they are enlarged on radiographs ?
Lymph node location
In health lymph nodes efface with the soft tissue in the cranial mediastinum
Sternal LNS
- level of S2 in the dog and S3 in the cats
- drain the abdomen and mammary glands
Mediastinal lymph node
- multiple lymph nodes along the cranial mediastinum ventral to the trachea
Tracheobronchial LNS
- LNS at the carnia
Describe a differential list for enlargement of the thoracic lymph nodes ?
Enlargement of thoracic lymph nodes differential list
- multicentric neoplasia - lymphoma, histiocytic sarcom
- disseminated fungal infection
- metastasis from the draining area eg mammary neoplasia to the sternal LN
- reactive hyperplasia from the draining area
Describe the normal appearance of the oesophagus ?
Oesophagus (barium)
Best viewed on the lateral projection
- on VD it is superimposed on the midline/ mediastinum and often not visable
M for mediastinum, M for middle
Identify this pathology on radiograph ?
Megaoesophagus
Focal
- vascular ring anomaly (VRA)
Generalised
- transient due to GA or sedation
- pathology - idiopathic, oesophagitis, myasthenia gravis, hypoadrenocortism, hypothyroidism
How to identify megaoesophagus
- wide cranial mediastinum
- use the lateral view to determine the location and cause
Identify this pathology on radiograph ?
Foreign body within oesophagus
To distinguish from a lung mass - not seen on VD view (where it is superimposed on the spine, midline contact same oppacity eg effacement)
Identify this pathology, and list the potential causes ?
Pneumonediastinum
Best identified on the lateral view of the thorax
Enhanced visualisation of the mediastinal structures - as the free gas provides excellent radiographic contrast.
Can now visualise clearly
- cranial vena cava + main branches of the aorta
- outside wall of the trachea
Define Pneumomediastinum and its pathology ?
Pneumomediastinum - gas in the mediastinum
- clinically it is insignificant but may lead to pneumothorax
- pneumothorax is clinically significant but can’t cause pneumomediastinum
- communicates with the neck + retroperitoneum so air can travel to and from these areas
Pathology
- blunt trauma (rupture of the trachea or oesophagus)
Identify this pathology and discuss its pathology ?
Mediastinal shift
Heart ‘shifts’ to the left or right (spinal process must be in line).
Can only assess on the VD view
Only two causes
- increased volume one side eg pneumothorax
- one side decreased volume eg lung atelectasis
Identify the structure “white arrow” ?
Normal thymus
‘sail boat’ often visible in young pups and sometimes kittens
Describe the anatomy of the pleura ?
What is pleural effusion andpneumothorax and what is the best view to identify these pathologies on a radiograph ?
Pleural effusion
- fluid in the space
- best assessed on the VD view (or DV)
Pneumothorax
- gas in the space
- best assessed on the lateral view of a radiograph
Describe how you would identify pleural effusion on a radiograph and the three degrees of severeity ?
Pleural effusion best assessed on a VD view
Three degrees of severity and diagnosis
1. Pleural fissure lines (thin pleural fissure lines may be normal - low severity).
2. Retraction of the lungs from the thoracic wall (moderate severity)
3. Lung leafing (severe)
Draw the right and left lung lobes in VD and lateral projection ?
Identify this pathology and describe its significance ?
Pleural fissure lines on a VD view
indicates a small degree of pleural effusion
Define effacemant ?
Identify three causes of increased soft tissue opacity and effacement in the thorax ?
Three reasons of increased opacity in the thorax
- Pleural effusion
- Alveoli lung pattern
- Mass - lung, cranial mediastinal, rib
Describe what features you would use to identify pneumothorax on a radiograph ?
Pneumothorax
(best view to assess is on the lateral views)
Pneumothorax identification
- seperation of the heart from sternum
- retraction of the lungs from the thoracic wall
Pathology pneumothorax
- trauma rupture of the lung
- trauma defect in the wall of the thorax
- sponatnaeous - rupture of lung bulla, migrating grass seed
How can a skin fold appear as pneumothorax on a radiograph ?
Skin fold artefact appears alike to pneumothorax
‘false pneumothorax’
Skin folds are frequently seen in radiographs but the skin fold will continue out side the thorax.
- additional should not observe on both views (pneumothorax apparent on the lateral view.
Define a tension pneumothorax and how you could identify this on a radiograph ?
Tension pneumothorax
Identify
Mediastinal shift of the heart away from the pneumothorax (due to increased presse in the affected side.
Non-tension pneumothorax
- usually no mediastinal shift
- there may be a mediastinal shift of the heart towards the pneumothorax (due to collapse of the lungs on the affected side)
- atelectasis
Identify the structures that the red and green arrow are pointing to in the photo ?
Red = aorta
Green = caudal vena cava
On the VD view you can only view the left side of the aorta as its effaces with the soft tissues of the mediastinum.
Describe what rule should be broken to indicate pathology of the vena cava ?
Pathology of the vena cava
If vena cava >1.5 x the aorta on the lateral view
- subjective identification of dilation on the lateral view
- care with describing the vena cava as dilated as it changes naturally with cardiac ryhthm
Causes
- right sided heart failure
- small CVC part of general hypovascularity
Identify the structures the arrows are identifying in the below pictures ?
Pulmonary artery and vein
(if struggling first identify the bronchus which bifurcates at the fifth vertebrae).
Pulmonary artery = red arrow
Pulmonary vein blue arrow
Artery - bronchus - vein
veins are ventral and central
Describe the two test that identify pathology of the pulmonary artery and vein ?
The two test pulmonary artery and vein
(they must pass both tests)
Test one
- are the PA and PV the same width
Test two
- LATERAL VIEW = PA and PV width where the 4th ribs cross them, must be < 3/4 of the thickest rib width close to the spine.
- VD VIEW = PA and PV where the 9th rib cross them should be <3/4 of the width of the rib
Describe how to carry out test two of the PA and PV on the lateral projection ?
PA and PV lateral projection
(first assess test one are they the same width)
- Assess the width of the vessels at the level where the fourth rib crosses them
- compare to the thickest part of the fourth rib at the level of the vertebrae
The vessels should be <3/4 of the width of the rib
Remember pick the lateral view in which the vessels are most visible
Describe how to carry out test two PA PV on the VD view ?
PA and PV VD view
(did they pass test one)
- Assess width of PA and PV at the level at which they intersect rib nine
- the width of the vessels should be < 3/4 the width of the rib.
What are the patterns of PA and PV abnormalities ?
PA and PV abnormalities
- Both are small
- Both are large
- PA is large
- PV is small
If both the PA and PV are small what pathologies should we expect ?
PA and PV too small
Hypovascular lung pattern
Blood loss
Shock
Dehydration
Addisons
Identify this abnormality and its pathology ?
Dilated PA and PV
Pathology
- Patent ductus arteriosus (PDA)
- Fluid overload
- Left sided heart disease ( potentially with secondary pulmonary hypertension)
Identify this abnormality and describe its pathology ?
Large PA
Pathology
- heart worm disease
- pulmonary hypertension (chronic lung disease, secondary left sided heart failure)
Identify this abnormality and describe its pathology ?
PV large
Pathology
- left sided heart failure
- usually mitral valve disease in small dogs and DCM in large breeds
Know how to approach the assessment of the heart on radiographs ?
Heart assessment
There are four rules
Three test for the size of the heart
- 2/3 assessment on lateral and Vd view
- intercostal space assessment 2.5-3.5 dogs, cats 2
- vertebral heart score
Heart shape
The only abnormalities which can be accurately assessed are the left atrium and main pulmonary artery MPA.
How do we carry out a 2/3 assessment of the heart ?
2/3 assessment of the heart
- Do the 2/3 assessment on the lateral and VD
- The heart is 2/3 of the height and width of the thorax (cat is more like 50% on the VD).
remember to angle with length of heart
How would you assess heart size against intercostal length ?
Measure intercostal length on the lateral view
Measure across the thickest section of the heart.
dog = 2.5 - 3.5 intercostal spaces
cat = 2 intercostal spaces
To assess for rotation the intercostal junctions need to be all at the same level.
- find cranial rib of pair + count from cranial rib to cranial rib
What is the third method of assessing the size of the heart ?
Vettebral heart score
objective
- does not replace subjective assessment
- not reliable in cats (use size + shape in cats)
- useful for a fast comparison over time
Describe how you would assess vertebral left atrial size ?
Vetebral left atrial size (VLAS)
measure from the ventral aspect of the carina to the junction between CVC and heart
Normal = is upto 2.3 vertebrae
When assessing the heart shape there are only two bulges which can be considered accurately.
What are they ?
The only two structures which can be accurately assessed
main pulmonary artery clock 1-2
Left atrium
remember radiography is not accurate for right side enlargement.
Describe the pathogenesis for mitral heart disease ?
Small dog mitral valve disease
(usually older small dog)
Degeneration of the mitral valve
- causes regurgitation so blood flows back into the LA causing it to dilate
- left side apical heart murmur, the severeity of murmur correlates to the severeity of disease
- left sided heart failure
Describe what we would observe to diagnose mitral valve disease ?
Mitral valve disease
(usually older small dog + murmur + dyspnoea)
radiograph or echocardiograph to determine dilation of the left ventricle
- if normal repeat six months later
- monitor resting respiratory disease ( complete radiographs to identify pulmonary odema)
Identify and describe this pathology ?
Dilated cardiomyopathy (DCM)
Large bred older dog
- dilated LA and LV reduced contractility
- may be observed as a large heart
- pulmonary oedema heart failure; caudal lung lobes
- can be left right or both (right sided heart failure less common)
- pulmonary oedema is usually more patchy than in mitral valve disease
What would your recommendations be in a dog supected of DCM and why ?
Dilated cardiomyopathy - large dog
Echocardiography is required to diagnose DCM, all dogs suspected should have a echocardiogram
- DCM is much more serious and they die sooner
- medications are expensive so diagnoses is needed
- CS are not as obvious
Radiographs used to identify pulmonary oedema
Describe what you would observe in a case of right sided cardiac failure ?
Right sided heart failure and pericardial effusion
- pleural effusion and or ascites
- most common cause of pericardial effusion
- pleural effusion can be detected on TFAST
- ascites on AFAST
- radiology is inaccurate never diagnose right sided heart failure on radiographs alone (must take it back to the animal)
Causes
- heart worm disease - test HW
- pulmonic stenosis, tricusid dysplasia - is a murmur present
- pulmonary hypertension - is there lung disease echo
Echocardiography to look for a right atrial mass causing the pericardial effusion.
How could you diagnose a pericardial effusion ?
Pericardial effusion
Diagnose
- generalised cardiomegaly
- TFAST
Identify and describe this pathology ?
PPDH Pertoneal pericardial Diaphragmatic Hernia
Radiograph
- enlarged cardiac silhouette
- diaphragm margin not seen (
- small liver
- the clinical signs do not fit with severe heart disease
Describe the pathology of heart disease in cats (HCM) ?
Hypertrophic cardiomyopathy (HCM)
70% of cardiac disease in cats
- cardimegaly (normal heart may appear in 10% of cats)
- the heart appears normal but has become thicker on the inside ‘hypertrophy’
- pleural effusion is common
Heart failure is the most common cause of pleural effusion in cats.
Identify this pathology in a cat ?
Hypertrophic cardiomyopathy (HCM)
- The heart in a healthy cat should appear as an almond
- HCM heart =peanut or valantine heart
- or generalised enlargement (no longer almond shaped)
- pulmonary oedema - patchy interstitual lung pattern
Should diagnose with echocardiography as CS are often subtle and cats may present with failure with no warning
TFAST pleural effusion
Radiography = pulmonary oedema
Provide the differentials for cardiomegaly ?
Draw the anatomy of the left and right lung lobe on the lateral projection ?
Where would the most ideal location in the lung be to observe pathology and why ?
Pathology is best observed in the aerated upper lung
The uppermost lobes contain the most air to contrast against soft tissue opacity.
Describe the different lung patterns which can be observed ?
The test for lung pattern
- Bronchial
- Alveolar
- Interstitual
- patchy area of interstitual lung pattern
- structured interstitual lung pattern nodules/masses
- diffuse unstructured interstitual lung pattern
Identify this pathology ?
Bronchial lung pattern
Best identified by
- donuts end on bronchi
- tram tracks (thickened bronchial walls)
The wall of the bronchi are not normally seen
Donuts are easier to see than tram tracks, so just look for donuts.
Describe the pathology of the bronchial lung pattern ?
Bronchial lung pattern
pathology
Dogs
- infection bronchial - bacterial, lungworm, heart worm
- chronic bronchitis - old small breed (50% have normal lungs
- eosinophilic bronchopneumopathy
Cats
- feline bronchial asthma (most common by far)
- lungworm - Aleurostrongylus abstructus
What is bronchial cuffing
Bronchial cuffing
The bronchi are normal but appear thickened
- interstitual lung pattern incteases opacityaround the bronchus
- can not differentiate radiographically from a bronchial pattern
Note - many patients look like they could have a mild bronchial lung pattern - if the patient has no CS it is likely normal.
Identify and describe this pathology ?
Alveolar lung patter
The black background becomes white
Abnormal lung - filling of the alveolar air space with fluid or cells, which displaces the air with soft tissue opacity.
Alveoli lung pattern signs
1. increased lung opacity - white lung
2. Effacement - heart, diaphragm, blood vessels
3. Air bronchograms
4. Lobar sign
Define increased opacity in the alveoli lung pattern ?
Increased lung opacity = white lung
- may be the only sign of alveolar lung pattern
- seen every time, may be the only sign
- there are other causes of increased soft tissue opacity (eg pleural effusion, mass).
What is increased effacement ?
Blur in other organs
Effacement of the heart or diaphragm is the easiest sign to recognise.
- effacement of vessels
- not always seen (the alveolar lung pattern must be in contact with the effeced organ)
- may also occur with masses, pleural effusion
Identify which lung lobe has increased opacity ?
Lung lobe = Left caudal
How would you distinguish between pleural effusion and alveolar lung pattern ?
Pleural effusion = retraction of the lungs + vessels remain visible
Alveolar lung pattern = no vessels are seen as they are effaced with the lung fluid
What is a air bronchogram?
Air bronchogram
This is a normal bronchus seen against a white lung
- pathognomic for alveoli lung pattern
- not seen every time
Often mistaken with normal bronchi - key are the PA and PV visible either side of the bronchus (not visible air bronchogram)
Identify green, blue and yellow dotted pictures ?
Green = normal
Blue = bronchial lung pattern
Yellow = Alveolar lung pattern
Describe a lobar border ?
Lobar border pathoneumonic alveolar lung pattern
Abnormal white lung next to normal black lung
- border of lung is hence vsiible
- not seen every time
- to recognise you need to know the location of the lung borders.
Describe the pathology of the alveolar lung pattern ?
Alveolar pattern causes
(what things fill the alveoli)
There are five
1. Pus - pneumonia
2. Water - oedema
3. Blood - haemorrhage, contusion
4. Cells - neoplasia (less common eg carcinoma)
5. Atelectasis (collapse) no air in the alveoli
What is the distribution of pneumonia ?
Pneumonia
cranial and middle lung lobes
ventral parts
Pneumonia takes three days before any improvement following treatment
Describe the distribution of oedema ?
Oedema - caudal lung lobes
- cardiogeni, often the right caudal is the first and worst affected
- non cardiogenic the caudal lung lobes are symmetrically affected and no signs of heart disease.
Will show big improvement with tx (frusemide) 6 - 12 hours
Describe the distribution of haemorrhage and neoplasia in the lung lobes ?
Haemorrhage - anywhere
- coagulopathy or pulmonary contusion trauma
Neoplasia - anywhere
- pulmonary carcinoma, can be a mass, mulifocal or lobar
- histiocytic sarcoma usually lobar neoplasia
Describe how you would identify a interstitual lung pattern ?
Interstiual lung pattern
A patch or areas/s of interstitual lung pattern not severe enough to be alveolar
The margins of heart and blood vessels may be hazy but can be identified.
- increased soft tissue opacity
- no effacement
- no lobar border
- no air bronchogram
Describe the pathogenesis behind an interstitual lung pattern ?
Interstitual lung pattern
Pathology
- pneumonia
- odema
- neoplasia
- haemorrhage
- the same as an alveoli lung pattern but to a reduced degree
Identify and describe this pathology ?
Diffuse unstructured lung pattern
There is increased opacity (diffuse) affecting all the lung and homogenous - not patchy
Most difficult pathology to recognise
- artefact (most common by far)
- underinflation
- fat dog
- normal for age
- lymphoma
- pulmonary fibrosis “ interstitual lung disease”
- pneumonia viral fungal or bacterial
For brachycephalic or barrel chested dogs the lungs are best assessed on the VD view.
What is a structured interstitual lung pattern and how is it recognised ?
Structured interstitial lung pattern
This is identified by observing
- single mass
- multiple nodules
- miliary nodular - lots of small nodules
Neoplasia is the most common cause for them all
provide a differential diagnosis between nodules and masses ?
Nodule < 2cm
Mass > 2cm
the smallest nodule that can be seen = 3mm
Why is this important - differentials
If observed small than three mm we know
probability
- end on blood vessel
- pulmonary osteomas
- thoracic wall
Miliary nodular
Structured interstitual lung pattern
haemangiosarcoma
Identify this pathology ?
Multiple nodules
Structured interstitual lung pattern
pulmonary metastases
Describe how you would carry out a MET check ?
Metastasis check - Met check
3 views minimum
- right lateral
- left lateral
- VD
- often most visible over the heart and diaphragm (due to summation)
- care diagnosing over a rib
Identify the differentials for shoulder and elbow pain in a young dog ?
Shoulder and elbow pain differentials young dog
The should can not be assessed for pain without also loading the elbow joint
- it is difficult to isolate the pain
- usually rad both the shoulders and elbow
Differentials
- osteochondrosis
- ununtied anconeal process (UAP)
- fragmented coronoid process
- osteoarthritis
- panosteitis
- incomplete ossification of humeral condyle (IOHC)
- fractures
The most common cause of shoulder pain in a young large breed dog is osteochondrosis, so just one lateral view is required.
Describe how you would radiograpgh the shoulder ?
Two standard views of the shoulder
Craniocaudal
Lateral view
Only exception - young large breed only requires a lateral view (Osteochondrosis)
Identify this pathology ?
Shoulder osteoarthritis
osteophyte within the shoulder joint.
Identify this pathology ?
Shoulder osteochondrosis
most commonly affected joint.
Describe the anatomy of the elbow joint ?
Humerus
- one condyle, with two articular parts; trochlea / ulna and Capitulum / radius
- most weight bearing is through the radial articulation
-medial and lateral epicondyles ridge is seen on the lateral view
Describe the location of the Supratrochlear foramen ?
Identify this pathology ?
This is not a pathology
Elbow seasamoid bone which is present in 1/3 of all dogs.
Compare the elbow anatomy of cats vrs dogs ?
Supracondyloid foramen
Explain the term elbow dysplasia ?
Elbow dysplasia
(young large breed dog)
Exclusively a term used for young dogs, once the dog >2yrs of age we refer to it as elbow osteoarthritis (OA)
- in a young large breed dog with elbow pain, it is always due to elbow dysplasia until proven otherwise.
- difficult to distinguish shoulder and elbow pain
Differentials
- Ununited anconeal process (UAP)
- Osteochondrosis (OC)
- Fragmented medial coronoid process (FCP)
Identify and describe this pathology ?
Ununited anconeal process (UAP)
Young large breed dog
Some large breed puppies have a normal accessory centre of ossification in the anconeal process.
- it closes 20-22 weeks
- if it remains open byond this it becomes ‘ununited’
Identify this pathology ?
Osteochondrosis (OC)
In the medial part of the humeral condyle only
- assess this specific location.
Describe appropriate procedure for radiographing the elbow ?
Identify this pathology ?
Osteoarthritis
Enthesophytes and osteophytes
- in a young large breed may be supportive of FCP
Describe how a diagnosis of FCP can be made ?
FCP = fragmented medial coronoid process
(young large breed dog)
- the most common cause of elbow dysplasia
- the fragment is usually not visable on radiograph (due to superimposition)
- requires CT and arthroscopy in combination for a definitive diagnosis.
If these are not available a diagnosis may be made through elimination
- of UAP and elbow OC and shoulder OC are ruled out.
Describe the pathology of incomplete ossification of the humeral condyle (IOHC) ?
Incomplete ossification of the humeral condyle (IOHC)
The growth centre in the humeral condyle fails to close / ossify
Pathology
The humerus has one condyle, which has two parts medial and lateral
- the normal growth centre between the medial and lateral condyle closes at two weeks and is complete by 8-12 weeks
- hereditary condition
- allow upto 6 months for individual variation before calling it ‘incomplete ossification’
Describe the signalment and clinical signs of incomplete ossification of the humeral condyle ?
Incomplete ossification of the humeral condyle
( not closed beyond six month of age)
Signalment
- french bulldog, spaniel cross
- can however occur in any breed
- age - can present at any age but 55% < 1 yo
- male > female
Clinical signs
- lameness can be caused by the IOHC itself (no fracture)
- pathological fracture with minimal trauma eg jumping
Identify this pathology ?
Incomplete ossification of the humeral condyle (IOHC)
Allow for individual variation, only consider pathology beyond six months of age.
- For diagnosis ensure the centre of the olecranon is over the mid condyle
- radiography is 83% sensitive but only if you remember this.
Describe the correct procedure for radiographing the pelvis ?
Radiography of the pelvis.
Standard view
- extended VD of the pelvis
- include stifles and top of the ileum of the hip
- use for assessment of hip dysplasia
Frogleg view
- additional view for the assessment of trauma
- pelvis fracture + slipped capital physis
Lateral view
- not required for hip dysplasia assessment
- important for assessment of trauma
Describe the pathology and clinical signs of hip dysplasia ?
Hip dysplasia
Signalment
- large breed dogs
Pathology
Developmental disease, the hips are normal at birth
-joint laxity (subluxation) is the earliest signs and the hallmark of hip dysplasia
caused by a combination of nutrition and environmental factors
- usually bilateral
How do you recognise hip dysplasia on radiograph ?
Hip dysplasia - there are two parts
- Subluxation - joint laxity (hip dysplasia)
- Osteoarthritis (OA)
This is caused by joint laxity. It is usually present by 1yo, so may be missed on radiograpgh at the time of diagnosis as it takes time to develop.
When you identify hip osteoarthritis (OA) what does it mean ?
Hip osteoarthritis (OA)
Remember hip dysplasia = young dogs, where OA is older animals >4yrs
Many older cats and dogs have osteoarthritis
- could be due to aging
- due to hip dysplasia when they were young
- avascular necrosis of the femoral head
Many tolerate hip OA very well and do not show signs of lameness
(Be aware signs of osteoarthritis may not be the cause of lameness in an older animal).
Describe and identify this pathology ?
Hip dysplasia
(Two parts osteoarthritis and luxation)
Identify on radiograpgh by
- extended VD view
- find edge of acetabulum
- find the centre of the femoral head
- the centre of the femoral head should be inside the acetabulum
Identify this pathology, and describe what it indicates ?
Morgans line
Enthesophyte along the attachment of the joint capsule on the neck of the femur
- it can be a normal finding
- earliest sign of osteoarthritis
Describe what you would observe on radiogragh to indicate osteoarthritis ?
Osteoarthritis
There are four major signs of osteoarthritis
- Morgans line, enthesiophyte
- Ring of osteophytes around the femoral head
- (periarticular) - Remodelling
- Change in the shape of the femoral head and neck (flatter head and thicker neck) - Acetabulum
- Osteophytes on the cranial aspect, remodelling change in shape, so that it is wider and shallower
Exam question 1.
Exam practice
- subluxation eveident right hip
- morgans line left hip
Compare feline hip dysplasia to dog hip dysplasia ?
Feline hip dysplasia
Not very common
- OA only affects the acetabulum
How do we assess the extended view of the pelvis for quality ?
Quality extended view of the pelvis
- collimate to include wings of the ilium and stifle joint
- patella in the centre centre
- obturator foramen must be symetric
Exam question two
- the ileum is not symetrical
- the obturator formamen is not symetrical
this indicates rotation
What are the two schemes for hip dysplasia certification ?
Why do we certify dogs ?
Certification schemes for hip dysplasia
CHEDS
PennHIP
The breed
- reduce incidence
Individual
- managemnt of an individual
Compare the Pennhip and CHEDS certification schemes ?
Certification schemes for hip dysplasia
Cheds
- extended VD view
- mostly assess for OA which occurs later
- may not select out dogs prior to breeding
- 20 years of use in Australia
PennHIP
- uses distraction view
- sensitive for subluxation
- high heritability
- can detect hip dysplasia in young dogs
- requires restraint of animal by hand = radiation exposure
Describe the signalment and pathology of avascular necrosis of the femoral head ?
Avascular necrosis of the Femoral head
Signalment
- small breeds, especially terriers
- usually young dogs (5-12 months old)
- usually unilateral
Pathology
Ischeamia
- causing necrosis and collapse + deformity of the femoral head
- inherited disease
Identify this pathology and describe its radiographic signs ?
Avascular necrosis of the femoral head
(Legg calve Perthes disease)
Radiographic signs
- usually unilateral (compare other limb)
- lucent areas (loss due to bone necrosis)
- femoral head collapses (smaller)
Chronic cases in older dogs will also have unilateral OA, possible due to avascular necrosis of the femoral head when they were young.
Identify this pathology and describe its signalment ?
Capital physeal fracture / slipped capital physis
Signalment
- more common in cats as they have delayed physeal closure (so can occur in adult cats)
- cats may be atraumatic due to delayed closure
- male possible overweight + desexed early
Radiographic signs
- Salter Harris fracture one
Identify this pathology and describe ?
Metaphyseal osteopathy (apple coring)
Cats
- Bone lysis of the femoral necks (apple core)
- often seen with capital physeal fracture
- young, often male, often bilateral
2 causes
- apple coring seconda after atraumatic captital physeal fracture
- apple coring occurs first. It may cause a capital physeal fracture
- delayed physical closure is often seen with it
Describe how you would identify sacroilliac joint sublaxation ?
Sacroiliac joint sublaxation
Use an extended VD view
- inhealth there is a smooth junction across the sacroiliac joint
- with sublaxation there is a divet
Never use the joint space of the sacroiliac joint, as this may appear enlarged with mild rotation.
Identify this pathology ?
Sacro iliac joint sublaxation
Recover the anatomy of the stifle ?
What is the most common pathology of the stifle ?
Crucial ligament disease (CCL)
Describe how you would diagnose a case of cruciate ligament disease ?
Cruciate ligament disease (CCL)
This is the most common cause of lameness in the stifle
- diagnose by cranial drawer sign (joint instability)
- may not be present if the rupture is partial
- but if there is often evidence of joint effusion on radiographsbefore cranial drawer sign
- joint effusion is only visible on the lateral view
- usually also OA, but not if acute
Surgery is based off clinical signs/examination + joint effusion - therefore it is absolutely essential that the lateral projection is perfect.
Identify the radiographic signs of osteo arthritis in the stifle ?
Signs of osteoarthritis
Periarticular osteophytes
Enthesophytes
+ / - joint effusion
The common location of pathology
- Trochlear ridges
- Patella
- CCL insertion
- Fabellae
Describe what you you need to ensure a quality radiograph of the stifle ?
Quality radiograph of the stifle
Lateral view
- peeing pose + belly tape (prevent the belly being superimposed on the stifle
- degree of flexion must be the same as standing (allows examination of the caudal aspect of the joint).
- condyles need to be superimposed, place a foam pad under the hip to rotate stifle down
Summary
1. One leg on the view
2. Not superimposed on the abdomen
3. Degree of flexion - same as standing
4. Femoral condyles superimposed
5. centre on the joint
How should you assess quality of radiograph on the craniocaudal view of the stifle ?
Craniocaudal view of the stifle
- patella in the centre of the femur
- Fabellae centered on the cortices of the femur
Remember it is ok to assess the stifle CC views on the extended VD of the hips if they are perfectly positioned. (less important to assess stifle effusion)
How do you identify medial petalla luxation ?
Medial petalla luxation
Best diagnosed through palpation
- may use radiographs to assess for concurrent disease
- often missed on radiograph as luxation is positional in most cases
- additional congenital limb deformity can appear as a luxation on radiograph
Identify this pathology ?
Tibial tuberosity avulsion
- always radiograpthe other leg
- 4-8 months old
- non traumatic - the petella ligament attaches to the tibial tuberosity and strong contraction of the quadraceps muscles can pull it off.
Write a differential list for aggressive digit lesions ?
Aggressive joint lesions
(lysis and perisoteal new bone)
Aggressive digit lesions are more common in dogs than cats
Common causes
- soft tissue neoplasm (soft tissue sarcoma)
- osteomyelitis (nail bed infection)
- cats 20% ‘lung digit syndrome’ secondary neoplasia
The cause can not be determined via radiograph.
- fine needle aspirate , amputate or histology
- thorax radiographs
Identify the likely pathology in a cat ?
Lung digit syndrome in cats
Primary lung neoplasia with metastases to the digits
- often present with digit lesion first
- radiograph the thorax for primary neoplasm
Poor prognosis. Don’t amputate the digits, as other lesions quickly occur in the remaining digits.
What is a stress radiograph, and when should we take them ?
Stress radiography
(instability of the carpus and tarsus due to trauma)
Joint instability can be determined by physical examination
So stress radiograps are taken too
- assess for fractures
- document the instability for referral surgery
- always radiograph the normal leg too
Identify this pathology ?
Osteochondrosis
In the tarsus appears as just a wider joint space medial ridge of the talus is most often affected
