Figure 5 . A ferret receiving analgesia via a CRI during splenectomy surgery . A second IV line is in place in case a blood transfusion is needed .
Figure 4 . A ferret recovering in an incubator , following a rightsided femoral head and neck excision . The ferret is on a ketamine CRI postoperatively , as well as methadone q4h , meloxicam q24h and gabapentin q8h . Note how he is lying comfortably on the affected side .
Constant rate infusions
With more invasive and painful procedures or conditions , the analgesia regime should be scaled up , with CRIs considered to allow better administration of multimodal anaesthesia and analgesia , enhance operative and postoperative outcomes , and improve the treatment of hypotension in exotic species [ 14 ] . Administering CRIs means the practitioner can titrate the rate to effect , and the plasma levels of the analgesic agent ( s ) are constant , in contrast to the peaks and troughs associated with repeated IM or IV injections , which lead to transient subtherapeutic levels [ 14 ] .
Butorphanol , fentanyl and hydromorphone have been described as single-opioid CRIs , or in combination with ketamine and lidocaine [ 8 , 12 – 14 , 22 ] . The authors are not aware of any adverse effects that arise with lidocaine CRIs in ferrets ( which can occur with cats ), but the authors ' experience of lidocaine CRIs in ferrets is only at a low dose and in combination with other agents .
The patient shown in Figures 5 and 6 was on a methadone , ketamine and lidocaine CRI for splenectomy surgery . This ferret had a second IV line in place , in case she needed a blood transfusion . In her left cephalic IV line , one port was used for temporary fluid boluses during anaesthesia and the other was used for the CRI .
Figure 6 . The ferret from Figure 5 recovering from splenectomy surgery . The patient is receiving analgesia via a CRI .
Local and regional anaesthesia
Local and regional anaesthesia is the most effective form of preventing pain , as it blocks pain perception at the site where pain occurs , providing ‘ true ’ analgesia [ 28 ] .
Local anaesthesia has the benefit of reducing the minimum alveolar concentration ( MAC ) of inhalant agents . In some cases , using local anaesthesia alongside sedation can mitigate the need for general anaesthesia , as well as having the advantages of being inexpensive and causing few adverse side effects .
Most techniques are relatively easy to perform , with examples shown on pages 19 and 20 ( Figures 7 – 15 ).
Simple techniques include splash block ( Figure 7 ), local skin infiltration before the surgical incision ( Figure 8 ) or intratesticular blocks before castration ( Figure 9 ).
Other techniques shown are an epidural ( Figures 10 [ 29 ] and 11 [ 30 , 31 , 32 ] ), infraorbital dental blocks ( Figures 12 and 13 ), local infiltration around a tooth ( Figure 14 ) and a pulp cavity block ( Figure 15 ).
18 Veterinary Nursing Journal