Our cat anaesthetic protocol has evolved over time to include sedation, iv induction, intubation and gas maintenance. The advantage of this system is it provides a controlled patient environment where adjustments can be made to anaesthetic depth and the patient is protected against gastric reflux entering the airways. A number of different sedative / iv induction agents can be used depending on individual cat requirements.
We recently ran a catchup surgery day for cat neuters. This posed some logistical issues which we got around by choosing a triple IM combination (butorphic, domitor, ketamine). By going down this route we didn’t need to intubate patients and anaesthetic duration and depth was quite adequate for cat spays (even the odd pregnant one). Those patients that took a little longer to wake up were helped along the way with antisedan.
A couple of surprising observations were made comparing the triple combinations with our standard protocol (usually combo of low dose ACP, temgesic or morphine, atropine (yes, I still like this drug despite a move away from its use) and Alfaxan or Repose + iso gas maintenance). Blood pressures are monitored using Doppler. With the standard protocol systolic, BP can drop quite low (anywhere between 60 – 80 mm Hg). This is a concern because NSAIDs are used post operatively for pain management. Our current policy is to administer NSAIDs to patients who’s BP has consistently been above 60 mm Hg throughout surgery. The triple group all had consistently high systolic blood pressures (around 120 mm HG). None of these patients were intubated. O2 levels were monitored using pulse-ox meters and were acceptable in all triple patients.
From a safety perspective one would tend to support the act of intubation and O2 supply. Studies have found though that intubation is one of the factors increasing feline anaesthetic mortality rates. This can be understood when you think about the tendency of cats to go into laryngeal spasm after any interference with the larynx. This coupled with an increased production of mucous in the trachea of many cats after intubation. As with any anaesthetic, the recovery phase is often the period of greatest risk. Patients are usually meticulously monitored during the procedure phase but less so (if at all) during the recovery phase. In summary, triple cat anaesthesia appears to be a very good alternative to iv / gas anaesthesia.
A list of anaesthetic options are included in Anaesthetic pro for those interested.