ECP 5 Flashcards
1
Q
Ultrasound what does it allow you to see, and what is the specificity and safety
A
- Allows evaluation of the internal structure of organs
- Dynamic ultrasound evaluation can allow evaluation of function
- Often has low specificity for identifying specific diseases - don’t know what it is
Cytology and histopathology may be required for lumps
No confirmed adverse biological reactions
2
Q
What is involved with preparing the patient for ultrasound and echocardiology
A
- sedate, clip, alcohol and gel - don’t need to clip or sedate horses if temperament allows
- Ultrasound gel - improve transmission of sound and allow probe to glide over skin
○ Need to clip a fair amount of hair up under the rib cage - Fast animals prior - doesn’t penetrate through dense tissue/food or gas filled spaces - morning generally less gas
- Echocardiography -> Can be performed without sedation, using an echocardiography table
3
Q
What are 3 important reasons to sedate during ultrasound
A
- Reduce stress and anxiety
- Reduce panting
- Relaxed abdominal wall - US probe can be pushed into tricky places
4
Q
What are the 3 types of ultrasound
A
1) B-mode imaging - most common - provides a real time cross-sectional 2D image
2) M-mode imaging - provides a graphical trace of motion over time and is used in echocardiography
3) doppler mode - provides information on blood flow
5
Q
Doppler mode what does it provide information on, how to interpret and the 2 types
A
- Provides information on blood flow -> is it moving in the right direction, regurgitation
- BART - blue away red toward, green in the middle (can reflect turbulence)
Types
○ Colour doppler superimposes direction and velocity of blood flow over the B-mode image
○ Spectral doppler allows quantification of velocity -> degree of stenosis, larger stenosis faster velocity
§ Pulsed wave doppler -> measures the velocity within a well-defined area, trace overtime of velocity of blood flow
Continuous wave doppler -> accurate for high velocity flow
6
Q
How are ultrasound images made
A
- Images are formed one scan line at a time, based on the pulse echo principle
§ Each line sends out sound that is reflected as an echo which is then detected then move across etc.
7
Q
what determines the depth and brightness of displayed echo
A
- The travel time of pulse to echo determines the depth of the displayed echo
○ Higher travel time arise from deeper tissues
○ Velocity of sound in tissue 1540m/sec - assumed so can place the spot on the - ALL TISSUES THE SAME - The amplitude of a returning echo determines the brightness of the displayed pixel
○ Stronger reflector higher amplitude brighter pixel
○ Weak reflector lower amplitude echo darker pixel
8
Q
What are the 3 interactions of sound with tissue
A
- Transmission - moves through
○ Occurs when tissues have similar density and velocity of sound in that tissue
○ Acoustic impedance (Z) = velocity (v) x tissue density (p) - Refraction -
○ Bending as energy passes from medium of one density to a medium of another density
○ Ultrasound probe can detect echoes that are reflected through an angle of <3degrees
○ Mostly ignores the refraction lines - Attenuation - tissue heating
A reduction in amplitude of sound due to absorption, scattering and reflection
9
Q
What are the 2 things that influence the rate of sound attenuation
A
- Distance -> greater distance, greater depth = more attenuation
- Frequency -> higher frequency = more attenuation
10
Q
Acoustic impedance mismatch what is it and what are the 2 main structures involved
A
- Ultrasound can’t penetrate through bone or lung due to this - use radiograph instead
- Bone: most sound is absorbed so high acoustic impedance -> casts a distal acoustic shadow -> cannot see internal structure of bone
- Lung: most sound is reflected so low acoustic impedance -> bounces between lung and detector -> thinks it’s an echo back -> reverberation artefact
11
Q
What does the ultrasound transudcer do and what are the 3 types
A
- Converts electrical energy to ultrasound, and coverts echoes into electrical signals
- Operator selects main frequency band used which changes based on:
Types - leads to different footprints (shape of field of view)
1. Linear array-> most common in larger animals and more dense, produces rectangular field
2. Curved array -> most common in small animal, produces trapezoid-shaped sector
3. Phased array -> tend to be specific for echocardiology - B-mode with colour doppler - triangular with narrow top
12
Q
Ultrasound transducer what should you consider
A
When selecting a transducer, consider the frequency and the footprint of the transducer.
- Low frequency transducers are used to image deep structures BUT LOW SPATIAL RESOLUTION
13
Q
Spartial resolution in terms of ultrasound what are the 2 types and what makes better resolution
A
- Best is achieved with high frequency transducers and when imaging within the focal zone
1) Axial resolution - distinguishing 2 objects parallel to the direction of the ultrasound beam
§ Depends on the wavelength
§ High frequency transducers have short wavelength and good axial resolution
2) Lateral resolution - distinguishing 2 objects perpendicular to the direct of the ultrasound beam
§ Depends on ultrasound beam diameters
§ Narrowest with high frequency transducers and within the focal zone
14
Q
Contrast resolution in terms of ultrasound what is it and what are the 2 things its controlled by
A
ability to display differences in echogenicity (greyness) of objects
1) Controlled by dynamic range
○ Use a low dynamic range for echocardiography
§ Difference between parenchyma and lumen
○ Use high dynamic range for abdominal ultrasound
§ Want to see all the shades of grey
2) Also our ability to perceive the different echogenicity
○ Best seen in low gain setting and in darkened conditions
15
Q
Define echogenicity, anechoic, hypoechoic, hyperechoic and isoechoic
A
- Echogenicity - relates to the relative brightness of a structure
- Anechoic - have no echoes within them and appear back -> urine filled bladder
- Hypoechoic - darker structure when two structures are compared
- Hyperechoic - lighter structure when two structures are compared
- Isoechoic - if two structures have the same echogenicity
16
Q
Nuclear scintigrapy what does it do and the 3 molecules involved
A
- images the distribution of a radiopharmaceutical within the body, using a gamma camera resulting in structure and function ○ Make the body radioactive 1) Radionuclide 2) Radioactivity 3) Radiopharmaceutical
17
Q
What is a radionuclide, radioactivity and radiopharmaceutical
A
1) Radionuclide
○ radioactive atom with an unstable nucleus
○ undergoes radioactive decay and emits the excess energy as radiation
2) Radioactivity [Bq]
○ rate of radioactive decay of a radionuclide with spontaneous emission of radiation
○ Half-life = time taken for radioactivity to reduce by half
3) Radiopharmaceutical
○ chemical containing a radionuclide, suitable for in vivo use to diagnose or treat disease
18
Q
What is radioactivity dosage and radiation dose
A
Radioactivity dosage - amount of radioactivity administered to a patient
Radiation dose - amount of radiation absorbed by the body tissues
19
Q
In terms of nuclear scintigraphy what does the radiopharmaceutical do, what is it made up of and example
A
radiopharmaceutical = radionuclide + ligand
- radiopharmaceutical allows the radionuclide to target the area of interest
○ Ligand - determines the physiologic distribution
Ligand eg - ○ 99mTc-MDP = Technetium Methylene Diphosphonate
§ bone scintigraphy
20
Q
How does technetium work in terms of nuclear scintigraphy and what is the half life
A
Technetium starts as Mo and undergoes beta decay -> Tc which emits gamma rays as transitions from metastable to stable state (we get Tc at the metastable state)
HALF LIFE of 6 hours from metastable to stable state -> want to order the day before doing the study as doesn’t last as long
Generally at background levels within 24 hours
21
Q
What are the 2 types of nuclear scintigraphy and what information do they provide
A
1) static acquisition - anatomic information - common to localise lameness in horses
2) dynamic acquisition - provides functional information - get multiple reading over time so see the movement of the radiopharmaceutical
22
Q
Static acquisition nuclear scintigraphy what information does it provide and what used for
A
- Static acquisition anatomic information - common to localise lameness in horses
○ Bone scan -> able to see an increase in uptake of radiopharmaceutical in areas of active bone turnover -> problem area
23
Q
Dynamic acquisition nuclear acquisition what information does it provide and the 2 main types
A
Dynamic acquisition provides functional information -> get multiple reading over time so see the movement of the radiopharmaceutical
1) Renal scintigraphy to measure GFR -> much more common in cats but still not as common
§ may be important to see when removing a kidney that the other kidney is functioning and won’t lead to kidney failure
§ Time activity curves allow you to quantify the GFR
2) Portal scintigraphy to diagnose portosystemic shunt - not as common anymore mainly just for laboratory testing
§ With a shunt over time the peak of radiopharmaceutical the peak occurs in the heart first and then liver or sometimes no peak in the liver -> BOTH SENSITIVE AND SPECIFIC FOR THIS DIAGNOSIS
24
Q
Dynamic acquisition what are the main advantages and disadvantages
A
Advantages
- Provides functional information
- May be very sensitive -> sensitive at detecting physiologic processes
Disadvantages
- Poor anatomic resolution
- May have poor to moderate specificity
○ May be a “Hot spot” in the right shoulder = increased bone turnover but is it neoplasia, osteomyelitis, fracture
○ THEREFORE scintigraphy is usually followed up with other images modalities and/or biopsy
- The patient emits gamma radiation
○ Technetium is excreted by urine, faeces and saliva
25
What is important in terms of safety with nuclear scintigraphy
○ Follow the ALARA principle to be safe around animals - SAFETY
§ TIME - minimise the amount of time you handle the radioactive patient
§ DISTANCE - isolation for 24 hours until radiation has reduced to background levels
□ Horses -> area of equine barn isolated
§ SHIELDING - wear gloves, PPE to prevent contamination with urine, saliva if around scintigraphy
26
Computed tomography how works, and the 2 main types
- Uses x-rays to produce cross-sectional images
○ Very tightly collimated beam and can detect what is happening within a slice of the patient
Types
1. Multiple detector array - rotate X-ray source and detector
2. Stationary ring of detectors - stationary x-ray but rotary detector
- Both used to recreate the internal structures with multiple slices used
27
Helical CT scanners what does it allow and the 2 main types
- Allow fast CT acquisition and can cover larger areas of the patient
- Types
1) Multi-slice helical CT Scanners = the best
§ Quicker to acquire information than single slice § Better resolution for reconstructed image using multiple scanner into sagittal plane
§ Can do 3D reconstruction as can reconstruct in any plane
2) Single slice scanner =
§ All information in transverse plane -> hard to reconstruct into sagittal plane
28
Concepts of nuclear scintigraphy what is a pixel element and the matrix and what does this influence
- Pixel element forms basis of 2D images, but represents information from a voxel (3D volume element - represent level of thickness)
- Matrix is the number of pixels used to reconstruct the image
○ 256 x 256 small matrix = poorer spatial resolution
○ 512 x 512 large matrix = better spatial resolution
§ But signal from the image becomes less as smaller voxel
§ Data file is also much larger -> how are you going to store this information
29
Concepts of nuclear scintigraphy what is the slice thickness and how does this change resolution
- Slice thickness - can influence the
○ Thicker slice - more x-ray absorption information so better contrast resolution, less quantum mottle but end up with volume averaging artefact (cause thick may have area of lung and heart but needs to average out these tissue - represents the in-between and therefore reduced spatial resolution
§ With the nose - have fine turbinates so not good to have thicker slices
30
CT number what is it and how does it relate to window width and level, what do you want with bone and soft tissue
The CT number measures the degree of x-ray attenuation (HU units) within a voxel
Air - very low -1000HU
Bone - very high +1000
- Window width and level can be adjusted to optimise the image for different tissues
○ Bone window: WW 100 -> wide window, high centre (high level of HU)
Soft tissue window: WW 250 -> narrow window, low centre
31
CT what are the 4 main advantages
- Acquisition is rapid
- Post processing can produce different series, long after the animal has gone
- Multiplanar reformates allow the image to be evaluated in ANY plane
- 3D reconstructions allow a global overview of the anatomy
32
CT when is it useful and safety
CT is useful when:
- Superimposition prevents identification of lesions
- Soft tissue information is required
- Lesions are suspected but not demonstrated on radiology or ultrasound
Safety
- ALARA principles apply
- CT involves much higher doses of radiation than radiography
- ABSOLUTELY no manual restraint
33
MRI - magnetic resonance imaging how does it work
- Shows distribution of hydrogen atoms throughout the body
○ Water is an abundant source of hydrogen atoms THEREFORE MR imaging is water imaging
- Hydrogen atoms rotate and act as a magnetic dipole
○ Normally they are all randomly aligned so no net magnetic moment
○ HOWEVER -> when in a strong magnet in hydrogen atom lines up -> become magnetised - SLIGHTLY POSITIVE IN THE DIRECTION OF THE MAGNETIC FIELD
○ If apply radio frequency wave at the right frequency knock the hydrogen atoms out of the alignment , as they return they release energy that is detected
§ RF coil emits the frequency wave AND detects the energy
34
MRI sequences what is it, the main sequence and how long does it take
MRI sequences are the pattern of radiofrequency pulses with different sequences emphasising different tissues
§ A study may then take 40-50 minutes to complete -> have to have a general anaesthetic
○ T2 weighted sequences - most important
§ Sensitive at detecting increased fluid with oedema, inflammation, neoplasia
35
MRI sequences what are the 3 main advantages and 2 main disadvantages
```
Advantages
- Anatomic information
- Very sensitive to pathology as most pathologies involve an increased water content (tumours, inflammation etc)
- Great detail within superimposition
Disadvantages
- Takes long time to perform
- Expensive
```
36
What are the 5 basic considerations for MRI safety
1. Static Magnetic Field
○ Don't bring in metal objects into the room!!
2. Switching Gradient Fields
○ Can induce electrical currents in wires placed on the patient and cause burns
3. Specific Absorption Rate (SAR)
○ Energy is deposited within tissue and may cause heating of tissue
4. Helium
○ From machine may leak into room -> decrease oxygen level
5. Noise
○ If in the room while occurring wearing head protection is recommended
37
Small mammal examination what are the 4 things you need and 3 other possible equipment
- Small scale (grams)
- Paediatric stethoscope
- Oral speculum (otoscope) -> larger green
- Pen torch (ophthalmoscope)
Possibly:
- Sedation - to do full clinical examination and sometimes when taking blood
- Slides.
- Scalpel blade.
38
Small mammal examination what is important
- ‘Over the stable door’ observations first.
○ Demeanour, respiratory rate, effort and pattern, movement, environment and owner interaction, cage, food, bedding, droppings/urination etc.
§ Get owner to take from the cage -> see how interact and if they will bite
ALSO normal examination - TPR, weight, hydration, palpation, mouth (last on all animals besides ferrets)
39
Venepuncture where take from in rabbits, ferrets, rats and mice and guinea pigs
- Rabbits: Lateral saphenous (cephalic, lateral auricular - NOT ARTERY, jugular)
- Ferrets: Jugular, lateral saphenous (cephalic, Cranial vena cava)
- Rats & Mice: Lateral tail vein (vena cava)
- Guinea Pigs: Lateral saphenous (femoral if sedated, jugular too short, cephalic small)
40
Rabbits what are important considerations when examining and where are the main problem areas
- Care: Fractured back or jumping off table.
- Place back into cage backwards.
- Husbandry issues: Bedding (not enough bedding - feet issues), stress
○ diet - fibre main issue - need heaps of hay, oxbo pellet SMALL AMOUNT, leafy greens - not lettuce
PROBLEMS
- mouth, gut (gut stasis EMERGENCY) and feet main issues (all areas can be an issue)
41
Rats and mice what causes the main issues, main problem areas and if see lump in mice or rat what most likely
- Husbandry often causes problems: ventilation, stress, food (too much fat, protein, sugar)
PROBLEMS
○ Eyes -> normal to have red tears
○ Ears
○ Respiratory tract - main issue -> cannot treat/cure, just manage, if predisposing factors like dusty cages
○ Dermis
LUMPS
○ Rats - most benign
○ Mice - majority of the time they are malignant
42
ferrets what is important during examination and main areas of concern
```
Chest cavity -> is quite small, not much reserve, auscultation -> gentle
- Areas of concern:
○ Genitalia,
○ Abdominal palpation (splenomegaly),
○ Lymph nodes - lymphoma
○ Ears (parasites)
```
43
Guinea pig main areas of concern and what is important in their diet
○ Parasites (ears and dermis)
○ Oral cavity (tongue entrapment) - molars grow over the tongue and trap
○ Abdominal palpation
: GI tract v’s Urogenital
§ Normal v’s Hard (Gut Stasis, GDV)
§ Urinary Calculi, Ovarian
○ Over 18 months of age the pelvis fuses -> dystocia a big problem SO SPAY YOUR GUINEA PIG
- Vitamin C: Scury - NEED TO BE SUPPLEMENTED
44
Reptiles list 9 objects that are needed for a clinical examination
1. Plastic guitar pick,
2. Gloves ( disposable v’s leather),
3. Towel
4. Scales (cat scales and small grams),
5. Doppler.
6. Ophthalmoscope
7. Slides
8. Stethoscope
9. Pen & Paper.
45
What are 5 important common problems in reptiles and what are most to do with
1) Sepsis -> red tinge on the skin is a common clinical sign
2) Metabolic Bone Disease
○ Can appear neurologic
3) Trauma
4) Egg bound
5) Vitamin deficiency : A - puffy eyes in turtles
Most are due to husbandry: lack of UVb, Wrong temperature, Wrong food, Wrong humidity.
46
Venepuncture where get blood from in reptiles and more specially chelonian and snakes
- Caudal tail vein (lateral v’s ventral): Think cow.
- In addition:
○ Chelonian: Brachial plexus, subcarapacial vein, jugular (lateral saph)
§ Common to hit lymph next to the vein
○ Snake: Heart
47
Snakes how many handlers needed, what is important in examination, and what is most important husbandry
- General rule of thumb: 1 handler for 3ft of snake.
- Ventral body palpation: most organs and food.
- Auscultation/doppler
- Sexing
- Temperature and humidity most important
○ If temperature too low can't digest rot from inside
48
Small and large lizards what are important in examination and handling
Lizards Small
- Easy to catch and hold. Difficult to restrain.
- Never grab by the tail
- Some have soft delicate skin.
- Injections not through the scale, up and under the scale
Lizards Large
- Often requires assistance restraining so you can examine.
- When scared may bite, scratch or whip. - Beware of the tail
- Cloacal examination for Kidneys
- Signs of sepsis along dorsal spines
49
Chelonians how to handle and difficulties with examination, what is important with euthanasia
- Difficult to restrain and examine
- Difficult to palpate much internally
- Auscultation: thoracic inlet v’s dorsal to carotid artery. Through carapace - with wet towel over the top
- Euthanasia -> keep warm, use doppler, keep overnight to ensure it is dead
50
What are the 3 main drugs we administer topically and where do these drugs go after delivery
```
What drugs can we administer topically
- Total parasiticides
- Transdermal patches - pain relief
- Topical anti-inflammatories
Where do these drugs go
1) Systemically absorbed
- Drug absorbed transdermally into the plasma
- Eg. Fentanyl patch
2) Locally acting
- Topical administered and act locally
- E.g fipronil
```
51
List some potential challenges of topical drug delivery
- Penetration of stratum corenum - intercellular, transcellular, sweat glands/hair follicles
- Absorption - lipid solubility, penetration enhancers (propylene glycol)
- Skin is an organ, not just a barrier
- Human safety
- Metabolism - phase I and phase II metabolic processes
- Species variation
52
Frontline main ingredient and how works, where does it go, what does it kill and what species don't use in
- Fipronil -> block GABA-gated and glutamate-gated chloride channel - - Hyperexcitation of insect nervous system -> may bite more and the animal seems more itchy
- Translocated dermally, no systemic absorption
- Kills adult fleas, prevents development of eggs, larvae and pupae
DON'T USE IN RABBITS
53
Advantage what ingredient and what does it do, where go and what does it kill
resistance issues
- Neonicotinoid - imidacloprid
- Acts selectively on insect nicotinic acetylcholine receptors
- Paralysis of nerve conduction and rapid death
- Translocated dermally to superficial epidermis, hair follicles and sebaceous glands
- No systemic absorption
- Adult fleas and flea larvae
54
Advantix what ingredient what does it do, what does it kill and what species don't use in
Advantage (neonicotinoid) + pyrethrin -> Prolongs period of Na+ conduction in action potentials - repetitive nerve firing
- Repels and kills paralysis tick (fortnightly dosing), bush tick and dog ticks as well as fleas (adult and larvae)
- Do not use in cats - reduced glucuronidation
55
Advocate what ingredient how absorbed what does it kill and control in dogs
- Imidacloprid + moxidectin (absorbed systemically)
Adult fleas, flea larvae, roundworms, hookworms, heartworm - NOT TAPEWORM (only issue if on farm (hydatids), flea issue and spirometra (reptile eating))
- Dogs - controls demodex and sarcoptes
56
Revolution what ingredient how absorbed what does it kill and what extra species can use in
- Selamectin - macrocyclic lactones
- Systemically absorbed
- Seems to be safe in collies sensitive to ivermectin-MDR 1 mutations
- Kills ctenocephalides felis (resistant to most other ML)
- registered in RABBITS
57
Activyl what ingredient why good, how work
NEW
Indoxacarb - oxadiazine insecticide
- Pro-insecticide - needs bio-activation in insect
- Irreversible hyperpolarization of insect nerve cell membranes - binds to sodium channels
Not absorbed systemically
58
What are the 3 important parasites for sheep and cattle and the main chemicals used to treat
```
Sheep -> Intestinal nematodes, lice, blowflies
Cattle -> intestinal nematodes, fasciola spp, ticks
Pour on vs jetting
Pour on
Macrocyclic lactones
Benzimidazoles
Triclabendazole
Levamisole
Sprays
Organophosphates
Pyrethroids
IGRs
Nicotinoids
```
59
Transfermal fentanyl patches how works, should you cut the patch
○ Alcohol-cellulose gel that contains dentanyl between two plastic layers
§ Inner layer - semipermeable membrane through which gel diffused into skin
§ Systemic absorption
- Cutting the patches - damage drug delivery system -> possible overdose
60
Compounded topical medications what species and area most used for, examples of drugs and what is needed
- Cats main spot in the ear -> may not have enough bioavailability from here
- Transdermal methimazole, fluoxetine, antibiotics
- Fluoxetine- 10% of oral bioavailability, could increase plasma concentration by increasing dose -> may lead to dermititis
- Need "penetration enhancers" e.g pluronic lecithen gel
- Many not potent enough for small volumes practical for transdermal therapy
61
What are the 2 main differentials for increased rectal temperature
Increased rectal temperature
- Hyperthermia (excessive gain of heat, not being able to remove
OR
- Pyrexia (normal response to inflammation, infection, neoplasia)
62
Define sepsis, what is the parthenogenesis and common source of infection
```
Sepsis -> infection associated with systemic signs
Pathogenesis of sepsis
- Microbial factors
○ Type of pathogen
○ Pathogenicity
○ Dose
○ Location
- Host response to bacterial infection
SOURCE - chest (penumonia) or abdomen (septic peritonitis)
```
63
What are the 3 physiological results from sepsis and how they relate to clinical signs
Loss of homeostasis
1. Loss of vasomotor tone - vasodilation
○ Why get injected mucous membranes, bacteria leads to increase NO which is a potent vasodilator
2. Dysregulation of inflammation and coagulation
○ Coagulation is initiated initially -> then moves to hypo-coagulation later
○ Tissue factor exposed during inflammation (bacteria) -> coagulation -> micro-thrombosis -> necrosis -> DIC when systemic
3. Endothelial, microcirculatory and mitochondrial dysfunction
○ Microcirculatory issues -> less lamina flow in capillary, increase slugging with white blood cells
64
Are you happy with a BP of 105mmHg from a doppler and what should you read BP in light of
- Normal doppler 100-140
- View blood pressure in regards to the heart rate -> in this case INCREASED heart rate to keep okay blood pressure
- So NOT HAPPY
65
What are the 4 steps in prioritisation of emergency case (suspect sepsis)
1. Acute resuscitative fluid therapy
2. Parenteral antibiotics
3. Samples for culture, susceptibility testing for antibiotics (if need to change)
4. Determine if surgical > as soon as medically and logistically feasible
DO WE NEED TO CUT IT OUT???? -> pyometra
66
What are the 3 different intravenous antibiotic therapy choices for septic patients
1) Empiric therapy - initial therapy of what you think it is
2) Broad-spectrum therapy - use of antibiotic that has broad-spectrum
3) Combination therapy - need antibiotics now, hit one agent two different ways
67
If have septic peritonitis what need to do and what is important to continue doing while giving fluid therapy
Septic peritonitis
- Need to do exploratory laparotomy to find where and remove
- If can't find supportive therapy and drain the effusion
KEEP LOOKING FOR EFFUSIONS
- Use of fluids may cause effusions
68
What are the 3 main issues with ruminants anaesthesia
1) Saliva -> large volume produced, regurgitation -> potential airway obstruction/aspiration
2) positioning - compression of diaphragm and abdominal vessels
3) Tympany - impaired eructation (gas accumulation in rumen) due to recumbency, sedation, anaesthesia -> respiratory distress and decreased cardiovascular function
69
Positioning of small ruminants during anaesthesia what can lead to and consequences of this
1. Compression of the diaphragm
○ When: lateral or dorsal recumbency
○ What: abdominal viscera compress the diaphragm
Consequences:
a. Decrease in ventilation
b. Increase ventilation-perfusion mismatch
c. Hypoxaemia and hypercapnia
2. Compression the major abdominal vessels
○ When in dorsal recumbency, abdominal viscera compress the major abdominal vessels
○ What: abdominal viscera compress the abdominal blood vessel
Consequences:
a. Decrease venous blood return
b. Decrease cardiac output and stroke volume
c. Decrease blood pressure, and tissue perfusion
70
What are 6 important ways complications and prevented in small ruminant anaesthesia
1. Withholding food and water does not totally preclude regurgitation and aspiration
2. Protect airway by intubating the trachea with a cuffed endotracheal tube
3. Dorsal recumbency avoided or kept to a minimum
a. Left lateral recumbency better
4. Use gastric tube and suction during surgery
5. Oxygen is administered
6. Intermittent positive pressure ventilation performed
71
What are some important parts of patient preparation for small ruminant anaesthesia and how to perform
- history/physical examin
food withheld for 24 hours, water 8-12 hours
- body weigh obtained
- Jugular catheter should be placed -> clip and scrub, local infiltration with lignocaine (wait30s-1min) and secure in place with couple of sutures (sometimes sedation not needed)
72
What electrolyte abnormalities are you most likely to see in a blocked goat, and what anaesthetic drug has been reported to cause pulmonary oedema and facilities in sheep
1) Increase K+ - most common and going to affect cardiovascular function
- Hyperkalaemia -> significant changes in ECG changes -> if above 7 DON'T ANAESTHETISE but reduce K+
2) xylazine - rare - alpha-2 agonist, if occurs then in big trouble
73
Premedication in small ruminants what should you use and what should you avoid
○ Sedation and muscle relaxation
§ Diazepam or midazolam
AVOID - alpha-2 as ruminants more sensitive and may cause respiratory depression, hypercapnia, and significant hypoxaemia, This may outlast the duration of sedation AND linked to death in sheep (xylazine)
○ Add analgesia
§ Butorphanol or Buprenorphine (longer duration of action)
AVOID - opiods due to GIT (tympany) issues
74
Induction for ruminants what are the 2 steps and possible medication choosen
1) Lignocaine over 2 min followed by
- Lignocaine “will” decrease laryngeal reflex (IV or Spray over larynx)
○ Decrease regurgitation and laryngeal spasm
2) Thiopental IV
○ Or propofol or Alfaxan - large dosage and expensive
75
Endotracheal intubation what are the 6 steps in ruminants
1. Animal on a table on left lateral recumbency head going down (Suction available) - to decrease regurgitation
2. A tie is placed around each the upper and lower jaw to facilitate opening the mouth and holding the head and neck extended.
3. Using a laryngoscope with a soper blade the larynx is visualised - through vocal cords know go into trachea
4. The cuffed endotracheal tube (ET) is inserted with the help a long stylet
5. The ET is secured and the cuff inflated
6. A mouth block can be used to protect the tube.
76
Maintenance of GA in ruminants what are the 2 main options and why use
1) Isoflurane in O2 - MAC lowest in cow
2) Paranteral IV in the field -> alfaxalone, propofol or porpofol with ketamine
- good in field if not able to bring around anaesthetic machine HOWEVER no sig advantages and more costly (unless <30min), risk of prolonged recovery and dose not eliminate endotracheal intubation
77
Monitoring ruminant anaesthetic what are NOT good indications and what should you monitor
- Rotation of the eye and movement are not useful indicator of anaesthetic depth in small ruminants.
- Heart rate should be within normal values, that is, 80 to 120 beats
- Respiratory rate should be between 20 and 40 breaths/min
78
what supportive therapy can you provide for cattle during anaesthesia, and issues with that
Fluid therapy
- Balanced electrolyte solutions (Lactated Ringers) infused at 5 mL/kg/hour IV
- 5% dextrose solution at 2 to 5 mL/kg/hour to prevent hypoglycaemia when < 3 months old - neonates
Issues
- Young small ruminants may become hypothermic during anaesthesia - need to keep them warm
Hypoventilation and apnoea are not uncommo
79
In terms of hypotension during anaesthesia what are the 2 modes vets have to go into to fix
1) If the hypotension is middle, the organs function will not be optimal but the patient life will not be in immediate danger. => “optimization mode”
2) If the hypotension is severe, the vital organs can suffer irreversible damages putting the patient in immediate danger. => “rescue mode”
80
Optimization mode what are the 3 steps within to decrease hypotension
1) check patients anaesthetic depth is adequate and adjust if need be, check HR
2) fluid therapy to increase blood volume and improve BP
3) IF STILL NOT ENOUGH -> improve myocardial contractility -> dopamine
In septic patient may need to vasoconstrict so give noradrenalin
81
Rescue mode what is the goal and what do you do
- The goal of the “rescue mode” is not to bring back the ABP to normal values. Indeed this increase in MABP is achieve in the detriment of peripheral organ perfusion and can be associated with a decrease in CO.
- The use of vasoactive drugs such as norepinephrine or phenylephrine starting at 0.5 microg/kg/min IV) allows redirection of the blood to the major organs in a timely fashion. - BLOOD FLOW TO MAJOR ORGANS
- Once the MABP is back in the 50s mmHg, an “optimization mode” treatment should be reinitiated
82
Recovery of ruminants from anaesthesia where to place and how to place
- Usually uneventful, under supervision in a quiet, comfortable, dry, and warm place
- To avoid ruminal tympany and regurgitation, small ruminants should:
○ be placed in sternal recumbency,
○ With the endotracheal tube left in place
○ Keep cuff inflated until swallowing
83
Loco-regional anaesthesia what used for in cattle and the 2 main blocks
- Ruminants usually accept physical restraint under sedation so in conjunction with local and regional anaesthesia often sufficient to enable completion of many procedures
EG - CESARIAN
1) paravertebral block -> L1 transverse process intertransverse ligament
2) Cranial epidural -> into lumbosacral space past ligamentum flavum
84
For limb IV regional anaesthesia and dehorning what use and important in goats
LIMB - no bupivacaine (toxic intravascularly) - lignocaine only
DEHORNING - Needle placement for desensitising the cornual branches of the zygomaticotemporal (A) and infratrochlear nerve (B) in goats - 2 nerves to the horn not just one
85
therapeutics in practice what regulation body involved, what are the 2 important drug schedules and proper waste drug disposal
APVMA - Australian Pesticides and Veterinary Medicines Authority
S4 - Prescription Only Medicine or Prescription Animal Remedy
S8 - Controlled Drug - locked cabinet only veterinarians can access
○ Movement within log book
DISPOSAL
- Incineration
- Landfill - mix liquids with absorbant ie kitty litter
- Do not flush unwanted chemicals -> AB residues & resistance, poisonings & allergic responses
- Exercise effective Stock Control –to limit wastage
- Educate clients on proper disposal
Follow local guidelines
86
What are the 2 main determinants of successful drug therapy
1. Coosing the most appropriate
○ Diagnosis, drugs, route of administration, dosage, dosing frequency, length of course
2. Communication
○ Patient and client factors, storage, language barriers
Compliance - does your patient actually receive the drug - first 2 steps
87
In terms of communication with achieving successful drug therapy what are the 7 things clients need to know
1. Why drug is necessary
2. Method of administration - demonstrate in consult
3. Appropriate storage - insulin refrigerated
4. Dose
5. Length of course
6. Adverse reactions and what to do if they occur
7. Species instructions
88
Opioids how reverse, caution with what drugs, side effects and contraindications
- Reversible with Naloxone
- Caution when used with drugs that inhibit cytochrome P450 (how it is metabolised) ie: Fluoxetine, Trimethoprim
Side effects
- Whine, pant
- Bradycardia
- Sedation
- Respiratory depression
USE WITH CAUTION - lower dose initially and asses response to pain
○ Head injury or any increase in ICP
○ Heart failure, Hypertension
○ Severely debilitated patients
89
List the 6 main opioids used for anaglesia what type of opiod and uses/ what species important for
1. Morphine–epidurals, intra-articular, full μ agonist, cats not iv
2. Methadone–iv, excellent analgesia, full μ agonist - MOST COMMON
3. Fentanyl–short t1/2, highly potent, CRI, transdermal, full μ
4. Buprenorphine–OTM (oral transmucosal), later post-op, partial μ agonist
5. Butorphanol–horses+++, useful for sedation, poor analgesia except in reptiles
6. Tramadol –cats good chronic pain (osteoarthritis), dogs + NSAID
90
Combinations with opioids why and what are the 4 main groups
- An Opioid’s actions can be enhanced and potential side effect risks reduced if used in conjunction with
1. Local anaesthetics –blocks, infiltrations, CRI’s - lignocaine
2. NSAIDS
3. NMDA receptor antagonists ie: Ketamine
4. Alpha-2 receptor agonists - ie: Xylazine, Medetomidine, Romifidine
91
NSAIDS how do they exert their affects and what does this result in and therefore what do we want from NSAID drug
NSAIDS exert their actions via inhibiting COX-1,2 and 3
1. COX-1, physiological -> leukotrienes that protect renal blood flow and gastric mucosa
2. COX-2, inflammation of disease and platelet aggregation
3. COX-3, central pain relief (ie: humans & Paracetamol)
In cats and dogs don't cross blood-brain barrier - NOT USED
WANT - COX-2 blocked but NOT COX-1
COX-2 selective firocoxib (best)
92
What are the 4 potential risks with NSAID use and therefore CONTRAINDICATIONS
1) renal toxicity
2) livery toxicity
CONTRA - pre-existing renal and hepatic disease, hypovolameia/dehydrated/shock
3) GIT ulceration
CONTRA - pre-existing GI injury/inflammation
4) prolonged clotting tendancy
CONTRA - impending surgery or bleeding tendancy (von willibrans)
93
NSAIDS when would you give to a client and how to tell
- Treating mild-moderate pain
- Patient is well hydrated –advise client -> DO NOT GIVE IF: vomiting, diarrhoea, inappetant, dehydration
- Good peripheral circulation
- Good renal function
- Normal sodium and water balance
- Ideally no liver disease
Need thorough clinical exam, Biochem, UA to assess all these
94
The use of cortiocsteroids and NSAIDS what to do
- Treat with misoprostol
- Ensure adequate fluid intake - may give IV fluids
- If have to use wash out periods of 48 hours
- AVOID IF POSSIBLE
95
What is important in terms of safe corticosteroid use
1) Know adverse effects -> prevent these
2) Always slowly taper the course of systemic CCS
○ do not stop suddenly – can cause iatrogenic hypo-adrenocorticism if suddenly withdraw CCS treatment
§ Ie: if treated for 1 week, then slowly reduce dose over another week
- Topical CCS do not to be tapered
○ CCS readily absorbed from skin, mucous membranes and GIT
96
List 8 adverse effects of corticosteroids and which most common
1. PU/PD - common
2. Thin skin and muscle wastage - long-term
3. Prolonged healing times
4. Polyphagia and weight gain - common
5. Iatrogenic hyper- adrenocorticism - high dose CCS
6. Rapid withdrawal can cause Addisonian crisis
7. Gastric ulcers - not common
8. Osteoporosis - with long term
97
What are the 3 main types of corticoseroids, examples and what used for
1. Short-Acting: Hydrocortisone, Cortisone, Fludrocortisone
○ (<12hrs) often used in topical preparations
2. Intermediate: Prednisone, Methylprednisolone
○ (12-36hrs) used for allergic disease, chronic inflammation, immune suppression
3. Long-Acting (36-72 hours): Betamethasone, Dexamethasone, Flumethasone.
○ Depot injection for long duration of action. Used for cats with allergies, parturition induction in cows.
98
List 5 different groups of drugs SHOULDN'T USE in cats
* Enrofloxacin, Lignocaine (use with caution), Azathioprine
* Paracetamol, buprofen, Aspirin
* Carprofen, Diazepam,
* Bromide, Permethrin, Cisplatin
* Chloramphenicol
99
List 5 things for the management of osteoarthritis
1. Weight loss
2. Nutraceuticals –Green lipped mussel, Glucosamine,
3. Physiotherapy –maintain muscle mass
4. Chrondoprotective agents –Pentosan (cartrophin), Polysulfate, Sodium
5. Analgesia -Gabapentin
○ NSAIDS – meloxicam, carprofen
○ Tramadol
○ Amantadine
100
Dental pain management what to use
- Local Anaesthetic Nerve Blocks –easy, quick, GP rotation - USE THEM
- Opioid - pre, intra and post-operative periods
○ Methadone, Fentanyl pre & intra & immediately post-op)
○ Later post-op; Buprenorphine, Tramadol (cats)
- NSAIDS–post-op
- Consider Ketamine CRI; intra & post-op - IF REALLY BAD
- Consider pre-treatment with Gabapentin -sedative also
