w/c 24-Feb-14 Flashcards
When is ACP contraindicated as a sedative in horses?
ACP is a phenothiazine. It is hypotensive and therefore contraindicated when there is hypovolemia/toxic colic.
Stallions = Priapism
Xylazine, Detomidine, Romifidine are used extensively in equine sedation. Why might they be combined with a low dose opiod?
These are alpha 2 agonists.
They provide deep sedation but can still respond to touch i.e. can still kick.
Adding low dose opiod removes response to touch
What are the most notiable side effects of alpha 2 use in horses?
Bradycardia, fall in cardiac output, biphastic blood pressure change (up then back) due to balance between vaso-contriction and cardiac output.
Considerations when using ketamine as an induction agent in the horse
Ketamine is a convultant and MUST NEVER BE GIVEN ALONE.
Ketamine is normally given with alpha 2 agonists e.g. Xylazine, Detmoidine, Romifidine)
GIVE ALPHA 2 FIRST!!
What is the function of Guiaphenesin (GG, GGE)?
Guiaphenesin is a centrally acting muscle relaxant and is NOT an anaesthetic. Always used in conjucation with anaesthetic agent.
Which is the only volatile anaesthetic agent licenced for use in the horse>
Isoflurane is the only licenced volatile anaesthetic agent.
Sevoflurane is used off licence
Which is more respiratory depressive; isoflurane of halothane?
Isoflurane is more respiratory depressive than Halothane.
Hypotension is also worse with isoflurane BUT IT IS LESS CARDIAC DEPRESSIVE!= Cardiac Output is well maintained
You have premedicated a horse with atropine 30 minutes into the operation the horses blood pressure falls to <40mmHg. What do you do?
-Reduce volatile agents (supplement analgesia by injectable agents
-Use large volumes of fluid
-Ensure horse that is recieveing IPPV is NOT Hypocarbic. Hypercarbia is great circulatory stimulant.
DO NOT USE INOTROPIC AGENTS SUCH AS DOBUTAMINE as this will cause Tachycardia in the horse premedicated with an atropine (anti-cholinergic)
You endoscope a horse and suspect it has a guttural pouch mycosis. What do you do?
Withdraw endoscope carefully and refer! If its affected carotid artery = fatal haemorrage.
Don’t stress horse!
A horse with unilateral epistasis has a visible yellow mass in its frontal sinus. What is the most likely diagnosis?
Ethmoid haematoma. Causes unilateral epistaxis with intermittent bleeding.
Why might a horse be given atropine pre op?
Atropine is a anti-cholinergic drug which reduces salivation and therefore reduces the risk of aspiration pneumonia
Hypoxemia in the horse is thought to come about due to
Marked ventilation/perfusion mismatching in the lungs leading to shunting of blood. Due to dorsal recumbancy
The deoxygenating effects of shunts are worsened by the low cardiac output.
Larger the horse= bigger problem.
Why is salivation a problem in ruminant anaesthesia?
Saliva is stimulated further by use of ketamine.
Can lead to electrolyte imbalances, also contains collaginases therefore if aspirated can damage lung.,
Or lead to aspiration pneumonia
Can also cause corneal ulcers
Why is bloat a consideration when a cow is anaesthertised?
Animals cannot eructate therefore if in lateral recumbancy the cardia is blocked = bloat.
Reduces venous return.
Horses are prone to hypotension. What blood pressure issues to ruminants tend to have>
Hypertension! Adult bulls and cattle often >200mmHG.
Due to changeover from para to sympathetic?
Or Hypoventilation therefore increased PaCO2 (but probably not)
Why do ruminants hypoventilate? What are the consequences of this?
Hypoventilate due to drug induced respiratory depression, large rumen.
Increased Co2 levels, decreased 02. ippv often used to manage but CARE as ruminants have less fibrous tissue therefore more prone to airway damage
Which sedative needs to be used with CARE in the pregnant animal?
The a2 agonist, xyalazine contracts smooth muscle therefore its use in pregnant animals is contraindicated.
Sheeps and Goats are VERY SENSITIVE to a2’s
Which drugs are most commonly used for induction in ruminants?
Ketamine (causes some muscle rigididity, laryngeal reflex remain) and Thiopentone (MUST GO IV!!!), Prolonged recoveries, not in thin animals
Which two NSAID’s are licened for use in ruminants and have no milk withdrawek time?
Ketoprofen and Carprofen,
NO LICENCED OPIODS IN UK!
Difference in accessing the jugular vein in cattle and horses?
Much more superficial in horses.
In cows its deeper.
CARE NOT TO DO INTRACAROTID INJECTION!
Important considerations for recovery of ruminants from anaesthesia?
Ideally in sternal recumbancy, allowing head to drop occasionally to drain saliva.
Extubate with cuff inflated. Suction perior to extubation
Sedation of pigs
IV access difficult so go IM initially.
Butyrophenone, Azaperone (dopamine antago)
Leave and wait 20 minutes.
Best venous access for pig
Warm water to vasodilate then ear vein.
What is malignant hyperthermia (MH)
Dominant gene of humans, pigs and horses.
Fault in a gene.
Inhalation agents cause it to trigger and is often fatal.
ATP depletion leading to muscle rigidity. The use of this ATP generates heat (temp >42)
Monitor for K+ to avoid hyperkaelemia from damaged muscle