Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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Ring Blocks


1)      Ring blocks

i)        Mix 1.0 mg/kg (0.5 mg/lb) bupivacaine with 1.0 mg/kg (0.5 mg/lb) lidocaine and:

(1)   Either 0.075 mg/kg (0.035 mg/lb) morphine or 0.003 mg/kg (0.0015 mg/lb) buprenorphine may effectively double the duration of analgesia1,2

(2)   Sterile water q.s., if needed, to total 1 cc volume for cats less than 2.5 kg (5 lb).

(3)   Sterile water q.s., if needed, to total 2 cc volume for cats 2.5 kg (5 lb) and over.

ii)       Inject subcutaneously at the three sites demonstrated below. Pinch the skin to tent it away from the deeper tissues and inject

iii)     You may drop the lidocaine if given prior to spay (gives bupivacaine time to take effect)

iv)     Bupivacaine has significant potential to cause cardiac toxicity

(1)   Calculate dose carefully

(2) Aspirate carefully before injecting



Click here for an MS Excel Ring Block dose calculator

Page References:
1 Buprenorphine added to the local anesthetic for axillary brachial plexus block prolongs postoperative analgesia. Candido KD, Winnie AP, Ghaleb AH, Fattouh MW, Franco CD: Reg Anesth Pain Med. 2002 Mar-Apr;27(2):162-7
2 The addition of opioids to local anaesthetics in brachial plexus block: the comparative effects of morphine, buprenorphine and sufentanil. Bazin JE, Massoni C, Bruelle P, Fenies V, Groslier D, Schoeffler P: Anaesthesia. 1997 Sep;52(9):858-62
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Last modified: June 1, 2011 .