Abstract

Phytocannabinoids like Cannabidiol (CBD) is the main non-psychotropic phytocannabinoid studied for medicinal purposes and currently considered legal for medicinal use for both humans and animals in many countries in South America. Several studies in dogs about CBD considered its administration safe in a wide range of low or high doses in healthy animals, and is currently studied for its analgesic and antiepileptic effects in some canine chronic conditions. The delta-9-tetrahydrocannabinol (THC) is the main psychotropic phytocannabinoid, and is commonly found in a limited range of concentrations (< 1%) in several pharmaceutical preparations in conjunction with CBD. Although accidental exposure to high doses of THC is known to cause neurologic signs and depression in dogs, safety studies of dogs exposed to preparations with a THC:CBD ratio 1:20 reported few adverse effects in low doses (0.1 mg/kg). Veterinary prescription of CBD with low concentrations of THC (< 0,2%) is currently legal in Colombia. Although many dogs are increasingly being prescribed with phytocannabinoid compounds, no information exists about anesthetic considerations in elective surgical and anesthetic procedures. The objective of this study is retrospectively review the effect of a single dose administration of two pharmaceutical grade CBD oils on basic cardiorespiratory parameters and anesthetic recovery of dogs undergoing elective surgery. Complete medical and anesthesia records of healthy dogs of the spay/neuter program of Corporaciòn Universitaria Santa Rosa de Cabal UNISARC whose owners approved a preoperative single dose of CBD were included for analysis. Dogs were considered clinically healthy based on physical examination, complete hemogram and serum creatinine and ALT concentration. Two types of CBD oils were used, a full spectrum cannabis oil with 200 mg/ml and THC up to 1 mg/ml (THC:CBD 1:20 ratio from Clever Leaves, Colombia) and a THC Free CBD oil with only 100 mg/ml (CBD only formula of Neviot ®, Procaps Colombia). Cannabidiol dose used was 2 mg/kg, the amount of product was calculated based on CBD concentration and randomly applied to dogs orally, 1 hour before any anesthetic premedication and closely monitored. Dogs then were routinely pre-medicated with standard care analgesia with meloxicam, tramadol and sedation with xylazine, after 20 minutes were induced and maintained with ether ketamine and/or propofol according to individual needs. Basic monitoring of heart rate, respiratory rate, pulse, rectal temperature was used during surgery and in recovery period. Once awake post-surgical pain was graded using the Glasgow Composite Pain Scale (GCPS) and any adverse effects or any other reaction was documented. Average heart rate, respiratory rate and temperature during surgery was calculated and compared between CBD and CBD:THC 20:1 doses using independent samples T test analysis for normal distributed variables and Mann-Whitney U test for nonparametric variables. Any adverse effect, anesthetic complication was documented. After retrospective analysis, 20 owners of dogs approved the CBD administration, 4 medical records were incomplete and excluded from the analysis and 16 dogs were included. There were 11 females and only 3 male dogs with a median age of 4,4 years (range 0,5-9 years). None of the dogs experience adverse effects during the first hour of observation. According to the type of CBD used, 7/16 animals received the THC:CBD ratio 1:20, no anesthesia complication was observed during surgery. In 9/16 dogs a CBD without THC was administered, only one dog experienced epileptiform activity during anesthetic induction. Average heart rate of dogs during surgery was not significantly different between CBD preparations (p = 0,39), also average temperature (p = 0,52) and respiratory rate (p = 0,056) during surgery was not statistically different between groups. During recovery 2 dogs in CBD:THC group show mild ataxia and only 1 dog in the CBD group. average pain GCPS scores were not statistically different between groups (p = 0,32). All dogs recovered well and discharged the same day and no one experienced moderate or severe adverse events. In this retrospective study a preoperative single oral administration of 2 mg/kg of Cannabidiol (CBD) oil in dogs was not associated with severe adverse effects. Some dogs experienced mild ataxia during recovery and no differences were observed between heart rate, respiratory rate and temperature between groups of CBD oils. The oil of THC:CBD with ratio of 1:20 was well tolerated in dogs receiving < 0,1 mg/Kg of THC. There was no difference between pain post-surgical pain scores between CBD oils.

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