VN May 2023

Vetnews | Mei 2023 37 With which procedures can a nerve block be useful? • Simple or surgical tooth extraction • Periodontal flap surgery • Oronasal fistula repair • Cleft palate repair • Biopsies • Excision of a mass or tumour • Mandibulectomy or maxillectomy • Root canal treatment • Reconstruction of bone and/or soft tissue following trauma Which local anaesthetics can be used? Agents used most commonly in veterinary dentistry are lidocaine, mepivicaine and bupivicaine. 6 Bupivicaine is the drug of choice due to its long duration of action. 1 Local anaesthetic agents can be combined with epinephrine which causes vasoconstriction and will aid in haemostasis. 1 It also increases the duration of action by up to 50%. 1 The uptake rate of an anaesthetic agent is reduced by 30% when combined with epinephrine and can decrease the drug’s toxic effects. 3,6 Do not use epinephrine in patients with uncontrolled hyperthyroidism, cardiac dysrhythmias and asthma. 1 The agent volume to be administered per area can range from 0.1ml-0.5ml for dogs (depending on body size) and 0.1ml- 0.3ml for cats. 6,1 Extreme care should be taken to not exceed the total safe dose of a drug when doing nerve blocks, especially in the smaller patients. Always aspirate before injecting to avoid intravascular injection, which may cause toxic effects that result in central nervous system changes such as muscle twitching, seizure, depression, coma and respiratory arrest. 6 These changes will probably be masked when the patient is under general anaesthetic. 6 Local anaesthetic agents are not very effective when used in infected tissue. 3 Possible complications Most complications with dental nerve blocks are rare. They can be avoided if thorough knowledge of anatomy is applied and if you are careful (aspirating and injecting slowly) when performing the block. 1 In human literature, complications such as haematoma at the injection site, iatrogenic soft tissue trauma and the breaking of a small gauge needle have been described. 6 Case reports of trauma to the orbit in cats caused by either maxillary or infraorbital nerve block have been published. 4,5 Extreme care should be taken when using these blocks with cats and small dogs. The inferior alveolar or lingual nerve can be permanently damaged with the inferior alveolar nerve block, although, again, extremely rare. 6,1 Rare neurologic complications reported include unilateral deafness, Horner’s syndrome, amaurosis, transient nerve paralysis and facial nerve palsy. 1,6 Dental Column Drug Onset Duration of action Total safe dose Lidocaine: Around 10 minutes. 6 1-2 hours. 3,6 Canine: 5-6mg/kg Feline 1-3mg/kg Mepivicaine: Around 5 minutes. 6 2-3 hours. 6 Canine: 5 mg/kg Feline: 2.5mg/kg Bupivicaine: Around 20 minutes. 6 3-10 hours 1 Canine: 2mg/kg Feline: 1mg/kg 1,3,6 >>>38