CRS 7 Flashcards
1
Q
List and describe common causes of puppy losses
A
- Dystocia
- Subsequent losses: born weak, congenital defecs e.g. ventricular septal defects, management and maternal causes, later infectious disease
2
Q
List and describe the common causes of kitten losses
A
- Dystocia
- Low birth weight
- Poor mothering/inadequate milk
- Neonatal isoerythrolysis
- Later infectious disease
3
Q
Explain the effects of exercise and training on the respiratory system
A
- Aim is to increase amount of O2 and CO2 out
- Respiratory and tidal volume must be increased
- At canter piston-pendulum theory applies
- Breathing and movement synchronised
- Rate of diffusion of gases across blood gas barrier depend on driving pressure gradient
- Blood gas barrier thicker in less athletic species and breeds
- Training does not alter ventilation but does increase VO2
4
Q
Explain the effects of exercise and training on the cardiovascular system
A
- Increase blood flow to limbs
- Cardiac output and oxygen carried in blood increased
- Blood redistributed around body
- During exercise spleen releases RBCs
- Warm up that includes canter releases blood cells
- With training, heart rate at given speed decreases
- Quicker recovery to resting rate post exercise
- Heart size increases
- Capillarisation in muscles increases
- Plasma volume increases
- Total RBC pool increases
5
Q
Describe the importance of the spleen and changes in packed cell volume in oxygen delivery during exercise
A
- Spleen releases RBCs
- Increases oxygen carriage
- Also increased viscosity of blood
- Increased PCV aids oxygen delivery during exercise as more oxygen can be taken to tissues in one cardiac cycle
- Important in exercise
- Becomes more difficult if too many RBCs produced
6
Q
Explain how performance can be limited excessive electrolye loss or imbalance
A
Reduced performance, hypovolaemia, muscle dysfuncion, nerve dysfunction, compromised renal function/damage
7
Q
Explain how performance can be limited by dynamic collapse of the respiratory system
A
- No support except dilator muscles
- Nasal cavities have bony supports, no muscles and vessels
- Pharynx has no support except tensor muscles
- Larynx has cartilaginous support, muscle contraction, decreases diameter but increases rigidity
- Bronchioles and alveoli have no support
- If any part collapses then volume of air reaching exchange surfaces will be reduced, meaning oxygen cannot be taken to the tissues
8
Q
Explain how perfomance can be limited by laryngeal hemiplegia
A
- Partial paralysis of larynx (usually left)
- Inadequate gas exchange so performance is reduced
9
Q
Explain how performance can be limited by a dorsally displaced soft palate
A
- Reduces ventilation
- Reduces performance due to less oxygen reaching the tissues
10
Q
Explain how recurrent airway obstruction can limit performance
A
- Lower airway inflammation reduces gas exchange
- Can be caused by environment, hyper-responsiveness, bacteria mycoplasma, parasites, viruses and allergy
11
Q
Explain how exercise induced pulmonary haemorrhage can limit performance
A
- Bleeding in lungs caused by high pressure
- Associated with locomotion
- Leads to veno-occlusive remodelling
- Reduced gas exchange
- Reduces performance as less oxygen reaches peripheral tissues
12
Q
Explain how equine infleunza can limit performance
A
- Destroys ciliated epithelium
- Disrupts mucociliary escalator
- Prevents gas exchange occuring
13
Q
Describe the different positions that can be used for dogs and cats for thoracic radiography
A
- Latera, both sides
- Dorsoventral (best for heart)
- Ventrodorsal (best for lungs, should not be done if breathing problem)
- Standing lateral
- Standing erect
- Recumbent VD with horizontal beam
14
Q
Describe the positioning for a lateral thoracic radiograph
A
- Legs pulled forwards so triceps muscle mass out of way of cranial thorax
- Wedge under sternum
- Include cranial abdomen so diaphragm can be seen on radiograph
15
Q
Describe the positioning for a DV thoracic radiograph
A
- Difficult in deep chested animals
- Ends of animal need to be upright to prevent twisting of body
- Hind legs tucked into body to provide further support
- Neck secured using sand bags
16
Q
Describe the positioning for a VD thoracic radiograph
A
- Should not be carried out if animal is struggling to breath as will put more pressure on lungs
- Tough used to support upper body
- Forelimbs adducted away from body, held in place using sandbags
- Head supported using foam wedge
- No axial rotation
- Hind limbs secured using sandbags
17
Q
Describe the radiographic appearance and relative dimensions of the normal heart
A
- No wider than 3.5 rib spaces on lateral view
- In VD should be 2/3 of width of thorax at rib 6
- Vertebral heart scora can be used to asses heart size
- Length measure on lateral view, number of vertebral bodies starting at cranial edge of T4
- Width measure similarly
- Vertebral heart score = L+W
- In dog normal is in range 8.5-10.5
- In cat normal is 8
- Heart should cast cardiac silhouette, more radiopaque than lungs
- Some of great vessels may be visible entering and exiting the heart
- Oesophagus seen dorsally to heart, enteric diaphragm
- Lungs completely radiolucent
18
Q
What are the limitations of cardiac radiography?
A
- Difficult to generate radiographs of diagnostic quality
- Movement blur
- Wide radiographic contrast range
- Interpretation
- Breed normals
- Age normals
- Inspiratory vs expiratory
- Poor radiograph may make it appear as though there is pathology when everything is normal
19
Q
What is angiography and what are the indications for angiography?
A
- Can be selevtive and non-selective
- Selective allows precise identification of chamer/vessel outline as contrast medium injected into chosen chamber
- Particularly useful for showing valve disease or congenital defects
- Provides definitive diagnosis
- Largely replaced by cardiac ultrasound
- Angiography does not usually cause damage to valves
- High risk as catheter is passes through artery
20
Q
Describe the interpretation of a thoracic radiograph
A
- Assess quality
- Assess artefacts: skin folds (if run long way down, skin fold), nipples, cartilage mineralisation, size and shape of cardiac silhouette, collapse of dependent lung due to doing a lateral view first
- Asses not heart and lungs: peripheral first, abdomen, thoracic skeleton, cranial mediastinum
- Look for lung patterns
- Cardiac silhouette: size, shape, increased or decreased sternal contact, whole enlargement or just one sided, changes to pulmonary vessels
21
Q
Describe the radiological appearance of the normal thorax
A
- Fluid and soft tissues have same radiographic absorbance
- Least to most absorbant: air, fat, soft tissue/fluid, bone
- Margins only visible where different radiographic tissues meet
- 6 lung lobes (right - cranial, middle, caudal, accessory and left - cranial and caudal) cannot be seen due to lack of contrast
- View as 3 areas
- Cardiac silhouette should be in contact with the sternum
22
Q
List the different lung patterns that may be visible on a thoracic radiograph
A
- Bronchial
- Alveolar
- Vascular
- Intersitial (diffuse or nodule)
- More than one pattern may be visible so need to identify main one in each area of the lung field
23
Q
Explain how a bronchial pattern may occur and how they would appear on a radiograph
A
- Thickening, calcification or fluid
- Thickening: bronchial opacity more prominent, may extend more peripherally, bronchi appear as doughnuts end on and tram lines side on, pulmonary vessels may be lost due to increased opacity
- Calcification: increases opactiy, no effect on thickness of bronchioles. Bronchi mineralised. Visible more towards periphery
- Fluid: generalised increase in opacity of bronchi, no increase in thickness, many causes
24
Q
Explain how an alveolar pattern may occur and how it would appear on a radiograph
A
- Alveoli filled with fluid (oedema, blood or pus)
- Cellular debris or neoplastic infiltrate
- Lung lobe collapse may occur
- Air alveolograms or bronchograms may ne present
- Lobar margins may be seen and blood vessels, heart and diaphragm will be obscured
- Alveolar pattern can be seen as a definite fluffy increase in opacity
25
Describe the normal and abnormal appearance of vasculature on a thoracic radiograph
- In lateral view cranial lobar artery and vein should be same diameter as proximal 1/3 of 4th rib
- In DV view, arteries and veins are the same diameter as 9th rib where they cross this rib
- If veins are bigger than arteries then this suggest congestive heart failure
- Increased vascularity increases blood in lungs for example in fluid overload or left to right shunts
- Decreased vascularity leads to an under circulation resulting in lung fields becoming more radiolucent
- Caused by right ot left shunts or hypovolaemia
26
Explain how an interstitial pattern may occur and how it would appear on a radiograph
- Thickening/infiltration of supporting tissues
- 2 types: diffuse (unstrctured, fine) and nodule
- In diffuse, only small amount of fibrous tissue, contrast still visible
- Can be caused by fibrosis, interstitial oedema, interstial haemorrhage, under-inflation or under exposure
- Nodular pattern very obvious, can be mimicked by artefacts from nipples
- Nodular interstitial patterns are caused by neoplasia
27
Describe the principle features of pleural and mediastinal disease
- Mediastinum sometimesvisible in lateral and DV views
- In lateral view trachea, aorta and caudal vena cava visible
- In DV lateral walls of cranial thorax, lateral edge of caudal vena cava and pericardail diaphragmatic ligament are visible
- In mediastinal disease, area more radiopaque and may not be possible to see structures usually visible in mediastinum
- Pleural cavity not visible on normal thoracic radiograph
- Pleural fluid leads to increased opacity of whole thorax
- On lateral view seen best in ventral and dorsal aspects of dog
- Fluid touching diaphragm not visible
- Fluid can be transudate, blood, lymph exudate or pus
- In pneumothorax whole thorax appears more radiolucent
- Cardiac silhouette separated from sternum
- Lungs visibly collapsed
28
Describe how ultrasound can be used to examine the heart and indications for its use
- Visualise lung surface, heart, pleura and pericardium, lymph nodes, thymus, space occupying lesions and vascular structures
- Slower heart rate of horses makes it easier to see what is going on
- Multiple views showing different chambers of the heart
- Long axis view goes from base to apex
- Short axis cuts through heart horizontally
- If the aorta is visible then must be the midline of the heart
29
Describe the limitations of cardiac ultrasound
- Ribs are in the way, small imaging window
- Panting interferes with imaging
- In large animal there is a large distance between the probe and heart
- Resolution of the image will be reduced
30
Describe what B-mode ultrasound is and what it is used for
- B-mode provides real time slice through tissues
- Routinely used for qualitative assessment of function and measurement of chamber dimensions
- Size of chambers
- How well heart is working
31
Describe what M-mode ultrasound is and what it is used for
- Measure movement along a single plain
- Plots single line against time
- Can be used to assess cardiac function and contractility (fractional shortening) as well as valve movement
32
Explain the indications for Doppler ultrasound examination
- Change in frquency that occurs when sound is reflected by a moving object
- Can be blood or myocardium
- If stationary then reflected sound is of same frequency
- If approaching then sound is reflected frequency is higher
- Can indicate what direction and how fast the blood is flowing
- Angle dependent and woks best with parallel and worst with perpendicular movement
- Frequencies usually colour coded so easier to see what direction the flow is
Usually used when valvular or congenital abnormality is suspected
- Continuous wave Doppler records velocity along specific line, similar to M-mode
- Can detect higher velocities not specific to each area
- Pulsed wave Doppler records velocity from a single location
- Colour flow Doppler reords velocity in a specific area
- Tissue Doppler can be used for muscle movement as well and only high velocities are detected (regional myocardial dysfunction can be identified)
33
List indications for ultrasound of lungs, pleura and pericardium
- Lower airways disease suspected
- Peripheral dimpling or an irregular lung surface may be visible
- Pericardial effusion can also be detected using ultrasound
34
Describe normal ultrasonographic appearance of the lungs, pleura and pericardium
- Lungs should be a smooth, freely gliding surface
- Pericardium cannot normally be visualised but may be visible in pericardial effusion
- Pleura should have minimum fluid in the cavity
35
List the limitation sof ultrasonography of the lungs, pleura and pericardium
- Pulmonary architecture cannot be visualised as is gas filled
- Can only detect lung surface, pleura and pleural space
36
What is the S1 heart sound?
- The "lub"
- Heard in all species
- Sound of blood hitting the mitral and tricuspid valves after atrial systole (block revered blood flow)
37
What is the S2 heart sound?
- "dub" sound
- Heard in all species
- Sound of blood hitting the semilunar valves after ventricualr systole (block reversed blood flow)
38
What is the S3 heart sound?
- Mainly heard in the horse
| - Sound of ventricular filling
39
What is the S4 heart sound?
- Mainly heard in the horse
| - Sound made by atrial contraction
40
What is the isovolumic contraction phase?
The stage in early systole where the pressure in the ventricle is greater than that in the atria so the AV valves are closed, but lower than that in the artery so the semilunar valves are closed
41
What is the isovolumic relaxation phase?
The stage occuring in early ventricular diastole where the pressure in the ventricles is lower than that in the aorta and pulmonary artery, but greater than that in the atria meaning that the AV valves and semilunar valves are closed
