Flashcards in CFC Deck (106)
what are bethanecol and carbachol?
They are resistent to AChE.
Both have GI tract effects.
HAve been used to induce gastric motility.
Carbachol used topically to induce miosis.
What are muscarine, pilocarpine and arecoline?
Pilocarpine is used as a topical solution to induce miosis. It is used for the treatment of glaucoma. It is contraindicated in uveitis and anterior lens luxation.
What are physostigmine, neostigmine, edrophonium and pyridostigmine?
They are reversible acetylcholinesterase inhibitors. They have a cholinergic effect initially.
Edrophonium is used for the reversal of on depolarising muscle relaxants and diagnosis of myasthenia gravis. it has a short duration of action.
Neostigmine is used for the reversal of non depolarising muscle relaxants and treatment of myasthenia gravis.
Pyridostigmine is also used for treatment of myasthenia gravis as it has moderate duration.
What are atropine and scolopamine?
Naturally occuring muscarinic antagonists (parasympatholytics).
Atropine can be metabolised in the liver. Used as a premedicant to decrease salivation. Used to treat OP toxicity. not recommended in horses.Can also be used for dilation of the pupil for examination, or used to increase heart rate, used with AChEI to prevent side effects from muscarinic stimulation when these agents used to reverse neuromuscular blockade.
Scoplamine is a naturally occurring agent used for drying secretions, contained in the antispasmodic buscopan, it has anti emetic agents.
What is glycopyrronium bromide?
A synthetic agent which acts as a muscarinic antagonist. It does not cross the placenta or the blood brain barrier. It has less CNS effects and is useful in caesarian sections. Used in ocular surgery to prevent vagal stimulation
What is tropicamide?
A muscarinic antagonist - used as a mydriatic. rapid acting short duration of several hours.
What is ipratopium bromide?
A muscarinic antagonist, used for bronchodilation in horses.
What is pheynylpropanolamine?
An a agonist - most important use is in the treatment of urinary incontinence in the bitch, it is administered orally. it has also been used as a nasal decongestant.
What is Dobutamine?
a B1 agonist - has primarily cardiac effects and will increase heart rate and force of contraction. dubutamine is used in equine anaesthesia to maintain a mean arterial pressure above 70mmHg.
What is Clenbuterol?
A b2 agonist - causes bronchodilation, uterine relaxation, used in the treatment of cOPD in horses, given orally or IV. can induce vasodilation and tachycardia. it also has a growth promotant effect.
What is terbutaline used for?
Also used as a bronchodilator but has more cardiac side effects. can be used as an alternative to propantheline in the medical management of conduction disturbances.
what is isoxuprine?
a b2 agonist - Used in the treatment of navicular disease, it induces vasodilation.
What are phenoxybenzamine and prazosin and what are they used for?
They cause relaxation of the urinary sphincter and promote urination.
What are the side effects of NSAIDS?
They are related to the inhibition of Cox1
GIT ulceration due to reduced synthesis of GI prostaglandin. Prostaglandins inhibit gastric acid secretion and promote mucous secretion. large intestinal lesions in horses associated to binding of PBZ to feed.
Nephrotoxicity - effect of inhibition of prostaglandin on renal blood flow as PGS dilate the afferent arteriole and allow activation of RAAS to constrict efferent arteriole.
How does aspirin work?
It irreversibly binds cyclo oxygenase . the side effects are GI erosions, haemorrhage and emesis. it has a selectivity for platelet COX. It is more effective as an antithrombotic agent at low doses.
Why can cats not metabolise paracetamol?
needs to undergo glucuronidation. NabQI binds to glutathione but if glutahione is saturated it binds to hepatic proteins causing necrosis. Treatment is with N-acetylcystine - a precursor of glutathione.
What are the metabolic effects of glucocorticoids?
Inhibit utilisation of glucose > hyperglycaemia
Increased glycogen storage in response
Protein breakdown and reduced synthesis
Redistribtion of body fat
NEgative calcium balance.
Elevation of liver enzymes
Induction of abortion/parturition
alteration of CNs function
Anti inflammatory effects
Decrease function of osteblasts and increase activity of osteoclasts.
Decrease action of T helper cells
Decrease accumulation of leucocytes in areas of inflammation
Decrease fibroblast function -r educe healing and repair
Which steroids are short acting and which are long acting?
Prednisolone, prednisolone, methylprednisolone are all short acting 24h.
Which steroids can be used intra articularly?
Methylprednisolone - rapid metabolism to MP, very low serum concentrations 24 hr, levels maintained for up to 29 days
Triamcinoline acetonide - higher and more prolonged plasma levels, levels in joint undetectable after 2 weeks.
Which drugs can be used to treat coccidia?
Ionophores - eg monensin, salinomycin. The therapeutic index of these is low - especially in horses.
sulphonamides - e.g sulfadimidine, sulfadimethoxine, sulfaquinoxaline. they interfere with folic acid synthesis.
Amprolium- used as a prophylaxis in chickens/turkeys - in feed or drinking water. Poor activity against some intestinal eimeria.
Toltrazuril - targets all stages, used in pigs and poultry for treatment.
diclazuril - used in calves, poultry and lambs for treatment and prophylaxis.
Decoquinate - disrupt coccidial cell transport, mainly for prophylaxis
What is the treatment of babesiosis?
May also be used for ehrlichiosis.
Where is contrast media injected into during myelography?
Into the subarachnoid space which outlines the spinal cord.
What technique of radiography should be used for the thorax?
high kv low mas
What is an interstitial pulmonary pattern?
An unstructured interstitial pattern with ground glass/honey comb appearance.
Ddx - expiration, age related fibrosis, pulmonary involvement in lymphoma, early in pulmonary disease.
If nodular interstitial - pulmonary metastasis, granulomatous lung disease, PIE.
Nodules smaller than 4mm cna not always be seen.
What is a bronchial pulmonary pattern?
Increased opacity of the bronchial walls, abnormal shape and diameter of bronchi, thickening of bronchial walls, tramlines (side on bronchi) and doughnuts (end on bronchi).
ddx - bronchitis, bronchopnuemonia, feline asthma, mineralisation of bronchial walls.
What Is an alveolar pulmonary pattern?
fluffy, ill defined infiltrate + confluence of abnormal areas. focal - lobar - perihilar - generalised, air bronchograms.
ddx - pneumonia, pulmonary oedema, pulmonary haemorrhage, neoplasia
What may you see on radiography of a pneumothorax?
Displaced ung margins
collapsed lung lobes
defined lobar edge
Radiolucency - no lung markings
elevated cardiac shadow
signs of trauma
What technique should be used for radiography of the abdomen?
Low to medium Kv and high MAs maximises abdominal contrast
expose during expiration
Use a grid if abdominal diameter >10cm
What are the typical ultrasound findings in acute pancreatitis?
Pancreas may be measurably swollen, hypoechoic, may contain solid or cystic masses, mesenteric fat inflamed and hyperechoic.
How does hypercalcaemia occur as a paraneoplastic syndrome?
It is a consequence of deregulation of homeostatic mechanisms between parathyroid hormone, calcitonin and active vitamin D.
Most common causes of hypercalcaemia are;
Malignancy and hypoadrenocorticism in dogs
Malignancy, renal failure or idiopathic in cats.
In non skeletal solid tumours as a result of tumour derived parathyroid hormone related protein and cytokines such as transforming growth factors, tumour necrosis factor and oestrogen functioning as osteoclast activating factors . e.g t cell lymphoma, anal gland adenocarcinoma, thyroid carcinoma, thymoma, malignant melanoma
Increased plasma PTH-rp concentration in a hypercalcaemic patient in the absence of renal failure gives a strong index of suspision for neoplasia.
Sometimes hypercalcaemia results from direct bone destruction in primary or metastatic tumours e.g myeloma, leukaemia, bone tumours, thyroid carcinomas.
What are the main clinical signs of hypercalcaemia in dogs and catS?
In dogs - pupd
in cats - lethargy/anorexia
The severity of signs depennds on the absolute magnitude, rate of rise, underlying cause, duration.
How can hypercalcaemia be treated?
IVFT 0.9% Nacl
Frusemide - causes decreased tubular calcium reabsorption at loop of henle
Corticosteroid - decreases gut absorption, bone resorption and increases renal excretion of calcium.
Calcitonin - decreases bone resorption
Bisphosphonates such as pamidronate, zoledronate and clodronate - bind ca2+ to hydroxyappetite crystals, decrease bone resorption
Sodium bicarbonate - promotes alalosis, increases protein bound calcium fraction
What toxic effects does cyclophosphamide have?
Bone marrow suppression
sterile haemorrhagic cystitis
What is chlorambucil used to treat?
Chronic lymphocytic leukaemia.
What are the possible toxic effects of azathioprine? what is this used to treat?
treat immune mediated disease
Bone marrow suppression
What are the toxic effects of doxorubicin?
Bone marrow suppression
What are the possible side effects of vincristine and vinblastine?
Phlebitis, peripheral neuropathy
vinblastine is myelosuppressive
Why is prednisolone used for lymphoma?
It is lymphotoxic and anti inflammatory which allows tumour shrinkage
What are the side effects of cisplatin? what is it used to treat?
should never be given to cats - pulmonary oedema
vomiting after infusion
What are the possible side effects of L asparaginase?
Describe the staging for lymphoma?
I - a single node
II - two or more nodes in an affected regional area
III - generalised lymph node involvement
IV - stage III plus liver and spleen involvement
V - bone marrow and non lymphoid organ involvement such as eye, CNS, lung
What is the best treatment for low grade lymphoma in a cat?
Oral prednisone and chlorambucil
why may hyperviscosity occur with leukaemia?
Hyperviscosity of the blood can occur when there are vastly elevated numbers of cells in the circulation or due to hypergammaglobulinaemia, which results from aberrant production of immunoglobulins by neoplastic B cells. IgA and IgM producing tumours cause more severe hyperviscosity than igG as the former are multimeric molecules. Clinical consequences of hyperviscosity include; bleeding diathesis
ocular changes - retinal detachment & haemorrhage
PUPD due to renal tubular and glomerular damage.
What is the reccomended treatment for multiple myeloma?
Mephalan and prednisone. If poor response - cyclophosphamide may be added. 85% of patients respond, MST 18 months. bisphosphonates may alleviate discomfort with osteolytic lesions.
What is polycythaemia rubera vera?
Primary erythrocytosis. Rule out any secondary cause of polycythaemia before a diagnosis of primary polycythaemia can be made. EPO levels are low in case of primary polycythaemia. The clinical signs are often due to an increased PCV and resulting hyperviscosity - neurological deficits, visual defects, lethargy and dullness.
What does haematology show with splenic haemangiosarcomas?
Polychromasia, ypochromasia, reticulocytosis, schistocytes, nucleated RBCs on blood smears.
What breeds are predisposed to histocytic sarcoma (malignant histiocytosis)
Rare in most breeds but very common in bernese mountain dogs and flat coated retrievers also at increased risk.
What are halsteds principles of surgery?
Sharp anatomic dissection
Gentle tissue handling
Obliteration of dead space - accurate tissue apposition
What are the properties of PDS?
Monofilament synthetic absorbable
80% strength at 2 weeks
60% at 6 weeks
What are the properties of monocryl?
Monofilament synthetic absorbable
50-60% strength at 7 days
20-30% at 14 days
What are the properties of vicryl rapide?
Braided synthetic absorbable
50% strength at 50 days
What are the properties of vicryl?
Braided synthetic absorbable. polyglactin 910.
Retention of 75% strength at 14 days, 50% at 21 days.
What are the properties of Maxon?
Monofilament synthetic absorbable .
50% stronger out of pack than PDS and remains stronger at 5 weeks.
90% strength at 1 week.
Which suture materials are permanent?
Mersilk (silk) - braided natural permanent, provides prolonged tensile strength retention in tissues up to 3 months.
ethilon - monofilament, synthetic, permanent.
Prolene - monofilament, synthetic, permanent
Which materials provide short term wound support?
Catgut, monocyrl, vicryl rapide
which materials provide medium term wound support?
Vicryl, dexon, biosyn
Which materials provide long term wound support?
What is atracurium?
A non depolarizing neuromuscular blocking agent. This would not only stop the dog moving but would prevent ocular movement during very light ga.
What is the fresh gas flow requirement in a rebreathing system?
Metabolic oxygen consumption -
LArge animals 5ml.kg-1min-1
In small animals 10ml.kg-1min-1
What is the fresh gas flow requirement in a non rebreathing system?
A higher fresh gas flow is required to flush the expired co2 away during the expiratory phase and prevent it being re inspired, so the fresh gas flow required is calculate dbased on the animals minute volume - 200ml/kg/min
For systems with the reservoir bag on the inspiratory limb the fresh gas flow is calculated as 1x minute volume eg magill system, lack, parallel lack.
for systems with the reservoir bag on the expiratory limb fresh gas flows are caalculated as 2 or 3x minute volume
ayres T piece - 2 or 3x minute vol
Bain 2 or 3x minute vol
What are the advantages/disadvantages to a circle system? (rebreathing)
rebreathed gas is wamer, moist, lower in o2 and anaesthetic as it has been mixed with the expired breath. o2 and anaesthetic must be replenished and co2 must be removed.
Why is higher fresh gas flow needed at the start of anaesthesia?
At the start of anaesthesia higher gas flows are required (30ml/kgmin) to maintain the concentration of anaesthetic agent within the breathing system. this is necessary because of the rapid uptake of anaesthetic into the animal at the start of anaesthesia, and the expired breath contains a much lower concentration of anaesthetic and will reduce the anaesthetic concentration within the breathing system. Also at the onset of anaesthesia, patients expire nitrogen, which may lower cicuit oxygen to hypoxic levels unless purged througha pressure relif valve. Denitrogenation is achieved using high flows for the first 10-15 minutes of anaesthesia or regular dumping of the bag.
What is minimum working soda lime volume?
The filled soda lime canister used to absorb co2 contains approximately 50% absorbent granules and 50% airspace. efficient absorption requires an airspace volume in excess of tidal volume, i.e minimum working soda lime volume is 2xvt.
What is a magill breathing system used for?
Efficient general purpose, but mechanical dead space, inertia and expiratory resistance preclude its usefull ness in cats or dogs under 5kg. The system should not be used for prolonged IPPV.
What is a lack breathing system?
Outer inspiratory limb surrounds an inner expiratory tube . lightweight and has less drag than a magill. Inner hose damage has been reported.
Parallel lack has largely replaced coaxial system due to potential risks resulting from damage to inner tubing.
Mini lack available for use in small dogs and cats.
What is an ayres T piece system?
Inspiratory hose connects to et tube and open ended expiratory limb at a t shaped connector. Gas flow 2 or 3 mv will avoid rebreathing, a rapid respiratory rate with a short expiratory pause - shoter time for expired gas to be flushed away may require higher flows. there is minimal dead space and low resistance, so this is ideal for cats, small dogs, neonates and birds. Can be used for IPPV but risk of barotrauma.
With jackson rees modification is an open ended reservoir bag on the expiratory limb. this facilitates IPPV.
What is a bain breathing system?
This has an inner inspiratory limb and an outer expiratory limb. A valve may or may not be present on the expiratory limb. flow rates vary 2 or 3 x mv, used in animals > 5kg, used for IPPV. low drag and mechanical dead space.
What are the side effects of propofol?
Dose dependent respiratory depression
post induction apnoea
Post induction cyanosis
Dose dependent cardiovascular depression
Not arrythmogenic & does not sensitise heart to catecholamines
Good muscle relaxation but ocasional muscle twitching
Decreases intracranial pressure, causes bronchodilation
What type of drug is ketamine? what are its side effects?
It has analgesic effects - NMDA receptor antagonist, has anti hyperalgesic properties, good for chronic pain, reduces MAC. It causes unconsciousness- dissociative anaesthesia. cranial nerve reflexes are maintained. It increases ICP, IOP. Causes increased HR and contractility, increased mvo2, transient respiratory depression, apneustic pattern, incraesed salivation, muscle rigidity and spontaneous muscle movements common.
Use with caution in : hyperthyroidism, hypertrophic cardiomyopathy, glaucoma, epilepsy, increased ICP.
What type of drug is alfaxalone and what side effects does it have?
A steroid anaesthetic - 'saffan' used to be with cremophor EL - dogs have anaphylactic reactions to. Not anymore. Can be topped up or used for TIVa as is non cummulative. Now no cremaphor so no histamine release (oedema & flushing of paws, pinnae)
What is guiaphenesin and what is it used for?
It is a muscle relaxant/neuro muscular blocker. It is not an anaesthetic and has no analgesic properties. It relaxes skeletal muscles. Licensed in horses.
What is the MAC? What is the value of this in halothane, isoflurane, sevoflurane and desflurane?
The minimum alveolar concentration of inhalational anaesthetic agent is the concentration that prevents movement in response to a supramaximal stimulus in 50% of unpremedicated subjects.
In the dog -
Halothane - 0.87
Isoflurane - 1.28
Sevo flurane - 2.36
In the cat -
What is the second gas effect of nitrous oxide?
During induction N2o very rapidly diffuses from alveolus to capillaries. Fractional concentrations of remaining gases in alveolus are increased. higher concentrations of volatile gasses in alveolus results in faster induction.
When should n2o not be used?
N2o diffuses into gas filled spaces faster than n2 diffuses out > worsens pneumothorax , gdv, vascular air emboli, dont use if enclosed gas filled space.
What agents can antagonise a neurmuscular blocking agent?
Edrophonium or neostigmine.
What happens to eye position during anaesthesia?
Eye position in dogs and cats becomes ventromedial, then central with deepening anaesthesia.
NB ketamine is associated with a brisk palpebral reflex and central eye position.
What is the onset of action and duration of action of Lidocaine, bupivicaine and mepivicaine?
Lidocaine - onset 10 mins, duration 60-90
Mepivicaine - onset 10 min, duration 90-180
Bupivicaine - onset 20 min, duration 4-8h
Describe the technique of proximal paravertebral nerve block?
Done most commonly to provide analgesia for abdominal surgery. local injected in proximity to the thirteenth thoracic and first two lumbar nerves. Inject just above the cranial edge of the transverse process of L1. Local infiltration of the injection reduces reaction to needle insertion. L5 is immediately cranial to tuber coxae.
Describe the technique of distal paravertebral nerve block?
T12, l1 and l2 are also blocked - the ends of the transverse processes of first, second and fourth lumbar vertebrae are identified. The needle is inserted parallel to and just ventral to the transverse process of L1. It is injected in a fan shaped pattern. hen the needle is withdrawn and re inserted just dorsal to the transverse process with another 15 ml injected as before. this blocks dorsal and ventral branches.
What does the auriculopalpebral nerve block block?
branch of the facial nerve - supplies motor fibre to the eyelids. the block producess eyelid akinesia that facilitates ocular examination and provides relaxation for ocular surgery. does not produce corneal or palpebral analgesia.
What does the infraorbital block anaesthetise?
Upper incisors, gums, upper lip and nostril. Injecting into the canal will desensitise the maxillary bone and many of the maxillary teeth on that side.
What does the mental block anaesthetise?
Lower lip, if injected into the foramen also produces analgesia of lower incisors and gums.
How is a retrobulbar block completed?
Long needle inserted through eyelid either dorsal or ventral to the globe, the globe is deflected by digital pressure as the needle is inserted.
What does mandibular block anaesthetise?
This is useful for any surgery involving mandible and teeth - the foramen is palpated just caudoventral to the last tooth. A mixture of lidocaine and bupivicaine can be injected. Another approach is medial to the horizontal ramus, advancing it parallel to the horizontal ramus until the tip is closed to the palpated foramen.
What is sacrococcygeal block used for and how is it done?
Fergusons reflex is abolished s- eliminates straining of uterus/rectum. Allows tail amputations, caslicks operation, epiziotomy etc. In cattle and horses the site for injection is done by pumping the tail which reveals the first intercoccygeal space as the most mobile. A 21 swg needle is then inserted approx 15 to the vertical.
What is lumbosacral extradural anaesthetic used for?
An area centred on midline lying over most dorsal palpable points of the tuber xocae is prepared - Just caudal to the dorsal process of the last lumbar vertebrae is the lumbosacral space. the needle should be inserted perpendicular to the skin and passed vertically towards spinal column.
What effects may liver disease have on anaesthesia?
Hypoglycaemia - dimished glycogen levels may predispose to gypoglycaemia
Hypoalbuminaemia - may alter drug binding and lower plasma oncotic pressure. This is of particular concern if protal hypertension follows attempted resolution of porto systemic shunts.
Hepatomegaly - may reduce FRC and limit lung inflation during breathing, predisposing to hypercapnia/hypoxia.
What are the typical clinical imbalances with vomiting?
post pyloric vomiting - Metabolic acidosis, hypovolaemia, hypochloraemia, hypernatraemia, hypokalaemia.
Pre pyloric vomiting - metabolic alkalosis, hypovolaemia, hypokalaemia, hypochloraemia, hypernatraemia.
What clinical imbalances are seen with diarrhoea?
What abnormalities may be present with GDV which may interfere with anaesthetic protocol?
Intra gastric pressure in creases, gastric circulation, caudal vena cava blood flow and portal venous flow are obstructed, venous return to the heart and cardiac output are subsequently reduced resulting in cardiogenic shock. Respiratory pathophysiology associated with gdv includes tachypnoea, lower FRC, lower tidal volume. Relive by paracentesis/gastrotomy. Increase in plasma pH due to sequestration of gastric contents within the stomach lumen > respiratory acidosis.
What may cause epistaxis in the dog or cat?
Any condition causing coagulopathy may manifest as epistaxis, as can hypertension and hyperviscosity syndrome such as multiple myeloma. Profound bleeding may also be seen if neoplasms or fungal plaques erode a major vessel.
What is the cause of pulmonary hypertension and how can it be treated?
Chronic fibrotic lung disease and secondary to left sided congestive heart failure.
Standard drug treatment is sildenafil and pimobendan .
What substances can be used as phosphate binders?
Dont use calcium salts in animals with hypercalcaemia.
What are the actions of an ACE inhibitor?
Dilation of teh efferent renal arteriole - reduces glomerular hypertension
Reduction of angiotensin II - this has an effect on systemic hypertension, may reduce podocyte hypertrophy and reduce renal fibrosis, may increase appetite and feeling of well being, may cause an increase in azotaemia as a result of reduction in GFR.
What is the best treatment for hypertension due to kidney failure?
ACE inhibitors in dogs
Calcium channel blocker amlodipine in cats.
What is the best treatment for a bladder tumour?
oral piroxicam for palliation.
What are the effects of cardiovascular disease on drug disposition?
Reduced volume of distribution will decrease the required dose of IVa.
Increased circulation time will increase the time to effect of IV induction agants.
Reduced cardiac output will decrease the induction time of inhaled anaesthetics. increased v/q discrepancy will increase induction time with inhaled anaesthetics. reduced peripheral perfusion will prolong redistribution and clearance. reduced renal blood flow will prolong redistribution and clearance.
Describe the changes that may be noticed on an ECG in heart disease?
Wide P wave - left atrial enlargement
Tall P wave - right atrial enlargement.
Wide QRS - left ventricular enlargement
Tall r - left ventricular enlargement
Small r - pericardial/pleural effusion
Alternate R waves of different height - pericardial effusion.
Deep S wave- RV enlargement
What is dipetalonema reconditum ?
A harmless subcutaneous parasite that also produces microfilaria.
What is the treatment for advanced heart failure?
Ace inhibitors (eg enalepril), diuretics eg frusemide, pimobendan, (positive inotrope) +- digoxin (controls ventricular rate in atrial fibrillation), +/- spironolactone depending on how bad it is. May add in dobutamine if end stage.
Where do the thiazide diuretics work?
The early DCt, they prevent sodium and chloride ion reabsorption. Increase the loss of K+ since more sodium is presented in the collecting tubule and more urine flow due to increased volume.
How is HCM treated in cats?
B blockers or calcium channel antagonists - they act as negative chronotropes and negative inotropes resulting in improved diastolic filling.
B blocker - atenolol
Calcium channel antagonists - diltiazem
amlodipine if hypertension (calcium channel antagonist)
How do loop diuretics work?
they act at the thick ascending loop of henle. They inhibit the co transport of Na / K / 2cl form the lumen into the tubule cell which reduces the hypertonicity of the medulla.
Why can thiazide diuretics be used to treat diabetes insipidus?
They cause loss of sodium and water in the DCt which leads to hypovolaemia, more sodima nd water is reabsorbed in the PCt, and less urine is in the loop of helne therefore less urine presented to the collecting tubule.
Which tumours have a high predilection for metastasis to the lungs?
canine appendicular osteosarcoma
canine and feline mmmary carcinomas
canine oral and naillbed melanomas
tonsillar squamous cell carcinomas
undifferentiated sarcomas and carciinomas of any origin.