w/c 10-Feb-14 Flashcards
Definition of MAC
Minimum Alvelolar concentration of inhalation agent requried to prevent movement in 50% of individuals in response to painful stimuli
MAC of a) Isoflurane
b) Sevoflurane
a) Isoflurant: 1.3%
b) Sevoflurane: 2.3%
Potency inversely proprotional to MAC
Which factors reduce MAC?
Reduce amount of drug required i.e. MAC.
-Hypothermia, old age or VERY YOUNG, intercurrent disease, pregnancy, use of opiods, hypoxia
Isoflurane and Sevoflurane cause more ____ than halothane
Isoflurane and Sevoflurane cause more vasodilation and respiratory depression than halothane. BUT Halothane more myocardial depression (CO) and sensitises to catechoamines = arrthymias
CHECK RESP DEPRESSION
What do Neutromuscular blocking drugs do?
Inhibit acetylcholine preventing propagation of action potential therefore muscle contraction. ALL SKELETAL MUSCLES.
What are important considerations when using NMB drugs
ensure adequacy of anaesthetic as animals won’t be able to move in response to painful stimuli
ANIMAL WON’T BE ABLE TO BREATHE! VENTILATOR
Reverse using acetylcholinesterase e.g. neostigmine/
What drug should be administered alone with NEOSTIGMINE?
Neostigmine is a acetylcholinesterase. Should administer anticholinergic e.g. atropine to prevent bradycardia following reversal of the NMB drug
Pulse oximetry measures the
Patients arterial oxygen saturation i.e. SaO2 NOT NOT PaO2
What does capnography measure? What is the normal range?
Capnography measures end tidal CO2 which approximates to arterial CO2.
Normally 35-45mmHg
How to detemine sufficient depth of anaesthesia?
Eyes rotate ventrally, minimal, sluggish palpebral reflex, loose jaw tone, no swallowing reflex.
Must visualise the laryngeal opening to make sure epiglottis is not pulled dorsally!!
How do you measure the length of endotracheal tube required? Why is this important?
Measure to point of shoulder; too long and it may enter the bronchi leading to unilateral perfusion
Important consideration when using ‘Intubeaze’?
Don’t spray more than once, easy to overdose; CAVE - Local anaesthetic overdose
5 Injectable GA agents
Propofol, Alfaxalone, Ketamine, Thiopental, Etomidate
Which 2 of the injectable GA agents can be used in food producing animals?
Ketamine and Thiopental.
ALSO ISOFLURANE ON INHALATIONAL LIST
When using ketamine as an injectable agent for maintenance, what only class of drug has to be given?
Muscle relaxant.
Ketamine is the only injectable agent that provides some analgesia
Soluble injectable agents will have a _____ partial pressure in lungs, therefore a ____ partial pressure in brain
More soluble= lower pp in lungs and brain. Will be SLOWER induction and recovery agents
But the following in order depending on their relative solubilities and therefore speed of induction
Sevoflurane, Isoflurane, Halothane, N20
LIST FROM SOLUBLE –> NOT SOLUBLE
LIST FROM SLOW –> QUICKER
Halothane –> Isoflurane–> Sevoflurant –> N2O
Why can Nitrous oxide not be used as an induction agent?
MAC in animals is 200% therefore cannot be used on its own.
Had mild analgesic properties.
Very insoluble therefore very fast onset.
‘Second gas effect’
DIFFUSION EFFECT AT END OF ANAESTHETIC - TURN OFF 5 MINUTES BEFORE AS DISPLACES OTHER GASES .
Check if staff are PREGNANT
Which ions are ‘thoretically’ released from the metabolism of sevoflurane?
Theoretically free fluride ions are released which are toxic to kidney. No problems reported clinically.
Compound A formation during reaction with hot/dry CO2 absorber - newer absorbers prevent this
Which induction agent tends to keep the eye more central (rather than turning ventrally as most)
Ketamine tends to keep the eye more central (esp in horses)
Which group of premeds can cause poor mucous membrane colour?
A2 agonists e.g. Romifidine, Detmoidine, Xylazine
Electrocardiogram is useful to measure….
Electrical activity of heart, diagnosis of arrthymias NOT NOT NOT CARDIAC OUTPUT
Normal systolic and mean MAP of dog and cat
Dog: Systolic: 140. Mean: 100
Cat: Systolic: 180. Mean 135
Which animals is dopler flow detection best in (for measurement of ABP)
Better in small animals than horses.
Add on 15mmHg in cats.
Useful in HYPOTENSIVE patients
In the adult racing horse, which respiratory pathogens are most common?
LRT diseases are more common and peak at 2YO.
Equine influenza, EHV 1&4, Step equi equi, Strep zooepidemicis, Strep pneumonia, Pasteurella, Actinobacillus
RAO definition
Recurrent Airway Obstruction.
Reversible lower airway obstruction, NATURALLY occuring. INCREASED EXPIRATORY EFFORT
Aetiology of Kennel Cough (Infectious Canine Tracheobronchitis, CIRD)
Frequently involves several agents:
Canine parainfluenza, Canine Adenovirus type 2, Bordetella bronchoseptica
How is Bordetella bronchiseptica pathogenic?
Attaches to cilliated cells (is cillostatic) although is also found in normal dogs.
If found with Canine Parainfluenza virus = more severe disease
Significance of Canine adenovirus type 2 (CAV-2)
TYPE 2 causes RESPIRATORY disease.
Rarely isolated due to good vaccination protocol
TYPE 1 causes HEPATITIS
Canine Herpesvirus
Systemic and often fatal disease in neonatal puppies. Under 3 days of age.
Renal, hepatic, lung necrosis.
Thermosensitive virus.
Vaccination avaliable for dam
What vaccinations are avaliable for Canine cornoavirus
There is a vaccination for the canine (enteric) cornoavirus but this doesn’t cross protect.
The vaccination for respiratory coronovirus is under development.
Which mycoplasma can be found in dogs with kennel cough (CIRD)?
Mycoplasma cynos ‘fried egg appearance on agar’
Clinical signs of Kennel Cough (CIRD)
Usually 3-7 days after exposure.
Cough (dry or productive), retching, particually during exervise.
Nasal, Occulr discharge, Sneezing.
Recovery without treatment in 1-3 weeks
When would you start to consider treatment in a dog with kennel cough?
WHEN systemic signs are present e.g. Depression, Pyrexia, Inappetance.,
Consider antibiotic, NSAIDs to increase appetitite etc.
Progression to bronchopneumonia caused by seconday bacterial infection
Which two infectious pathogens are most likely isolated from a dog with systemic kennel cough?
Canine Distemper virus, Strep equi subsp. zooepidemicus
Which parasite do we need to rule out when an animal presents with dyspnoea?
DO FAECAL EGG COUNT FOR Angiostrongylus
Role of IgA in kennel cough
More IgA stimulated from intanasal vaccines on mucosal surfaces.
IgA NEUTRALISES antigen on cell surface
How long before kenneling should the kennel cough vaccination be given? Which vaccines are avaliable?
B.bonchiseptica: At least 5 days before kennelling.
Immunity is short lived
Canine parainfluenza: Live attenuated
Canine Adenovirus (cav 1 AND 2) cross protection
What type of virus is Canine Distemper?
Morbillivirus REPLICATES in lymphoid tissue therefore immunosuppresiv . Shed in all body fluids therefore spread by aerosol/ close contact
Pathogenesis of Canine Distemper
Virus enters respiratory tract, spreads to tonsils and local LN, infects monocytes/macrophages, viremia and systemic dissemination.
Dogs with insufficient immune response with have respiratory, gastrointestinal, CNS signs.
Causes IMMUNOSUPPRESSION therefore secondary bacterial infections
Aside from the vominting.GIT and occasional CNS signs what else is common in dogs with Canine Distemper?
Hyperkeratosis of foot pads and nose i.e. ‘hard pad and hard nose disease’
Also have distemper teeth- hypoplasia of the enamel
What would you expect on haematology for a dog infected with CDV?
Haematology: Lymphopenia
Serology: IgM indicitve of recent infection
FERRETS highly susceptible to CDV
A dog had pyrexia, haemorrgaic, nasal discharge and sudden death. PM showed severe necro-haemorragic and fibrino suppurative bronchopneumonia. What is the likely pathogen?
Streptococcus equi subs. zooepidermicus.
Relative common in horses (associated with abortion/URT)
Not likely to be dog - horse transmission
Likely to be dog-dog via fomites.
High mortality due to sudden onset
Zoonosis
Upper limit for horse temperature
Above 38.5 degrees = hyperthermic
You tend to investigate heart mumurs in horses when they are above grade
IV or more.
Grade II systolic right murmur is probably tricuspid regurg
How to differentiate DV for VD view?
DV - ANIMAL ON STERNUM. Policemans hat appearance
VD- GAP between diaphram and cardiac silhouette
If you have identified dilated oesophagous in a radiograph, what else should you check for?
Aspiration pneumonia; check VENTRALLY! Alveolar pattern
How do you differentiate veins are arteries on radiograph?
Veins are VENTRAL (on lateral view) and MEDIAL/CENTRAL (on VD view)
Two Ddx for cochal destruction
URT disease. Conchal destruction indicates aggressiveness. Either Aspergillosis (checkboard apperance) or Neoplasm (more uniform/ less lucent)
What causes increased expiratory effort?
Intrathoracic obstruction e.g. Tracheal collapse or lung worm.
Mediastinal widening is suspected when the cranial mediastinum is…
twice the width of the vertebral bodies
How can the crus of the diaphram be used to determine if a xray is taken from right or left lateral view>
RIGHT: Crus parallel to each other. vena cava enters first crus
LEFT: Crus angle with each other, vena cava enters second crus
Alveolar pattern is characterised by ______
Ddx for diffuse alveolar pattern are…
Alevolar pattern is characterised by lack of age in the alveoli of the lung.
Diffuse: Severe bronchopneumonia, severe oedema, near-drowning, smoke inhalaton
After taking a bronchoalveolar lavage of a horse following poor performance you get Simonsiella. What do you conclude from this?
Oropharangeal contamination (Simonsiella only found in oropharynx), therefore repeat sample
When an animal presents with dyspnoea, a useful indicator for differentiating heart disease from pulmonary disease is…
MEASURING THE HR.
Often normal in respiratory disease
In which breed of dog is pulmonary fibrosis common?
West Highland White terriers.
Especially the older ones
An inhaled forign body is likely to be present where?
Right caudal lung lobe.
Bification of trachea is slightly unsymmetrical
What pulmonary pattern would you expect in a dog with lungworm? (angiostrongylus)
Alveolar pattern
A dog is in acute severe dyspnoea, radiographs are surprisingly normal. This prompts the clinician to think…
Pulmonary thromboembolism!
Or upper respiratory disease
4 causes of dyspnoea in small animals.
- obstruction of airways
- loss of thoracic capacity
- pulmonary parenchymal disease
- others: metabolic etc
What are the physiological/metabolic causes of dyspnoea?
Respiration may be stimulated by changes in pH (i.e. acidosis increases RR), blood supply, PAIN, pulmonary thromboembolism
Which organisms contribute to the ‘Cat Flu’ complex?
Feline Herpes Virus (FHV-1) = Feline rhinotrachitis
Feline Calicivirus
Chlamydophila felis
Bordetella bronchiseptica
Feline Viral Rhinotrachitis
Same as Feline Herpes Virus (FHV-1) - Corneal ulcers, reproductive problems .
If kittens affected, encepahlitis and hepatitis
Which of the cat flu virus’ cause more occular signs?
Chlamydophila felis.
Environmental elementary bodies
Conjuctivitis, nasal discharge.
Can also get corneal ulcers with Feline herpes virus
How do you diagnose infection with different organisms in the cat flu complex?
Virus: PCR for nucleic acid or virus isolation.
Serology NOT useful if have been vaccinated!
How to diagnose a) Chlamydophila b) Bordetella?
a) Chlamydophila use PCR
b) Bordetella: Bacteriology
Virus isolation for FCV, FHV
When Chamydophila felis or Bordetella are isolated, the antibiotic of choice is normally…
Oxytet or Doxacycline.
NOT IN YOUNG ANIMALS = Stain enamel
Which two cat flu organisms can be chronically shed by infected animals? I.e. stress
Feline herpes and feline calicivirus
A terrier with a dry and hacking unproductive cough is most likely to have
Chronic bronchitis/ bronchioectasis .
Cough is often exacerbated by excitement or exercise / change in environmental temperature..
Cough easily induced by tracheal palpation
What is the prognosis of a terrier with chronic bronchitis/ bronchoectasis?
Very unlikely that a cure of the clinical signs will be achieved. Management changes equally as important as bronchodilators.
- maintain clean atmosphere
- dogs are normally overweight- dietary changes
- limited but regular exercise
How do bronchodilators work? What are some examples?
Either b2 agonists (theophylline, terbutaline) or muscarinic antagonists (atropine)
Treatment for chronic bronchitis/ bronchoectasis
- Bronchodilators
- Antibacterial agents (only if bacterial contam)
- Expectorants/ mucolytics
- Cough suppressants (if not productive)- NOT IF ALVEOLAR PATTERN
- Anti-inflammatory medication (corticosteroids)
Canine Lungworm is…
Angiostrongylus vasorum. Affects pulmonary vasculature and may cause pul hypertension. (also Filaroides but less common).
Associated with systemic coagulopathy and bleeding from any site.
Increased ________ noise would b e expected in a dog with lungowrm
Inspiratory noise (and increased inspiratory is extrathoracic non-fixed and restrictive disorders e.g. [pleural effusion)
A yorkshire terrier with a ‘quacking’ cough is most likely to be
Tracheal collapse
Increased expiratory effort (intrathoracic airway obstruction)
The most common cause of persistant coughing in the cat is
Feline asthma -F eline allergic airway disease (FAAD).
Bronchoconstriction in response to antigenic stimulus. Increased EXPIRATORY effort (Intrathoracic obstruction)
What would you expect on blood test for cat with FAAD?
I.e. feline asthma. Would expect a circulating easinophillia . May be a bronchial pattern on radiograph.
Treatment of FAAD?
In emergency situation oxygen therapy and IV corticosteroids (.e.g methyprednisalone succinate), bronchodilating agent e.g. atropine (ONLY EMERGENCY DUE TO SIDE EFFECTS)
Atropine is
Muscarinic receptor antagonist
Which species for pulmonary fibrosis most commonly affect?
Idiopathic condition most commonly affecting whwtS.
Poor prognosis.
Progressive cough and dyspnoea. Marked crackles on ausculation
Why should atropine be reserved for emergency use in horses?
Muscarinic antagnoist.
Reserved for severe dyspnoea.
Causes gut stasis = colic (along with other side effects)
Clenbutarol is
non selective b2 agonist
Side effects include tachycardia and sweating and it also works on b1 receptors.
Reduce dose if side effects
Which valve pathology do horses normally not get?
Horses get regurgitant valves
Rare for them to get stenotic valves (therefore normally flow murmurs)
How do tests for influenza and equine herpes vary>
Herpes can be isolated from blood (as it causes a viremia)
Influenza = nasoswab ELISA
Can do paired serology for both
Markers for inflammation in the horse:
High fibronogen, globulin
DDx for high biliburbin in horse
- Liver danage
- RBC destruction
- Anorexia
Why is fluroquinolone not an appropriate antibiotic for preventing of secondary bacterial infections in horses with influenza
- Opportunitic pathogens normally Strep and Staph, fluroquinolones is not active against these.
- Should not be used as first line antimicrobial
