Abstracts

Medication Related Osteonecrosis of the Jaw (MRONJ), also referred to as Antiresorptive Agent Related Osteonecrosis of the Jaw (ARONJ) and formerly known as Bisphosphonate Related Osteonecrosis of the Jaw (BRONJ), is a rare but intractable disease in humans linked with long term use of potent antiresorptive medications, such as bisphosphonates (BP) and denosumab, and angiogenesis inhibitors. The American Association of Oral and Maxillofacial Surgeons (AAOMS) has preferred the term “medication related osteonecrosis of the jaw” (MRONJ) to include other antiresorptive and antiangiogenic drugs that have also resulted in necrosis of the mandible, maxilla or both. This talk will discuss salient aspects of medication related osteonecrosis of the jaws in cats, specifically bisphosphonate related osteonecrosis of the jaw. Though more commonly published in human literature, this presentation is rare in cats.

Referring to recently published study of 20 cats with MRONJ, learning objectives of this lecture include discussing MRONJ in cats (and humans) and how this disease is thought to occur, and then highlighting presenting concerns, clinical findings, risk factors, diagnoses, interventions, outcomes (including adverse events), and follow-up that can aid in improved prognosis for cats with MRONJ. Given the limited literature in veterinary patients, discussion about MRONJ in humans will be included, where relevant.

The aforementioned case series revealed that cats with feline idiopathic hypercalcemia treated with bisphosphonates (alendronate) may be at a risk for development of MRONJ, a serious oral condition with significant morbidity. Prior dental extraction sites in patients concurrently treated with bisphosphonate medications were often associated with MRONJ lesions. Therefore, any needed dental surgery should be performed prior to the use of bisphosphonates where possible. Diagnosis of MRONJ was made by a correlation of diagnostic findings and patient history. No single diagnostic, or combination was pathognomonic for lesion diagnosis. As well, there were no statistically significant associations between patient variables assessed and the overall patient outcome.

Given the serious morbidity of this disease, and its rarity in the literature, the hope is that this talk will bring light to MRONJ diagnosis and treatments in cats, to ensure appropriate monitoring, client discussion, diligent follow-up and rapid diagnosis and treatment, if a lesion is to ensue.

References:

1. Hatunen SL, Anderson JG, Bell CM, Campos HC, Finkelman MD and Shope BH (2024) A retrospective case series on bisphosphonate related osteonecrosis of the jaw in 20 cats. Front. Vet. Sci. 11:1436988. doi: 10.3389/fvets.2024.1436988
2. Ruggiero SL, Dodson TB, Aghaloo T, Carlson ER, Ward BB, Kademani D. American Association of Oral and Maxillofacial Surgeons’ position paper on medication-related osteonecrosis of the jaws—2022 update. J Oral Maxillofac Surg. (2022) 80:920–43. doi: 10.1016/j.joms.2022.02.008
3. Stepaniuk K. Bisphosphonate related osteonecrosis of the jaws: A review. J Vet Dent. (2011) 28:277–81. doi: 10.1177/089875641102800413
4. Yoneda T, Hagino H, Sugimoto T, Ohta H, Takahashi S, Soen S, et al. Antiresorptive agent-related osteonecrosis of the jaw: position paper 2017 of the Japanese allied committee on osteonecrosis of the jaw. J Bone Min Metab. (2017) 35:6–19. doi: 10.1007/ s00774-016-0810-7

Introduction:
Locoregional anaesthesia techniques (LA) have become integral part in managing pain associated with dental interventions. Inferior alveolar nerve (IAN) is one of the branch of the mandibular division of the trigeminal nerve (CN V). Blocks of the IAN (IANb) are generally effective, but their success hinges on precise technique, anatomical knowledge, and appropriate anaesthetic volume. Incorrect landmark identification, volume related complication (VRC) and mechanical complication (haematoma, tissue swelling, local nerve damage) have been reported sporadically (1-3). Data on incidence, management and outcome of IANb related complications in clinical practice remain limited (4,5). In this retrospective, descriptive, multicentric study we present a pattern of complications occurred after IANb.

Material and Methods:
Data were collected retrospectively from the digital archives of 7 institutions over the course of 4 years period (2019-2022).
Age, breed, weight, sex, drug, dose, approach and location of IANb were registered (Table A). LA used were selected based on surgeon preference, procedure and desired length of postoperative analgesia. IANb was performed using either intra or extraoral approach by 7 different operators. Volume administered followed standard protocols from established reference (6). Location of the lingual trauma and mitigating interventions were recorded. Lesions were scored as mild, moderate and severe subjectively and categorically. Follow up was present for all except one case.

Results:
13 dogs reported complication postoperatively. Mean patient age was 5.5 years, and mean body weight was 20.6 kg. Procedures performed included extraction, root canal treatment, mandibulectomy, and gingivectomy.
2/13 (15%) dogs received combination of Bupivacaine 0.5% and Lidocaine 2%. 9/13 (69.2%) dogs received bupivacaine as a sole agent, 2/13 (15%) dogs received combination of bupivacaine 0.5% and buprenorphine.
IANb was performed bilaterally in all dog except one.
Of the 13 dogs with reported lingual auto-inflicted self trauma, 8 received intraoral IANb and 5 IANb via extraoral approach. The self-trauma occurred in a variable time after the extubation. Duration of chewing episodes was limited in all apart for 1 dog where it lasted for 3 days post-procedure. Mitigation strategies for lingual self-trauma included: sedation or re-anaesthesia and suturing, muzzling, titrated analgesia and antibiotic treatment. Follow-up data was available for all except 2 dogs. Most dogs reported complete healing of the lingual lesions within 3 months and normal eating behaviour.

Discussion:
Current recommendation for LA dosing is typically linked to body weight. This series describes a pattern of complications across multiple practices. It cannot establish causality (retrospective, uncontrolled, subjective scoring) therefore it does not allow calculation of complication incidence/risk after IANb.

Conclusion:
In this study we describe lingual auto-inflicted self-trauma as complication following IANb. Our results suggest that, albeit rare, is a possible event, mostly noticed in the immediate recovery. Breed, operator, or procedure are likely to play a role, while correct technique and volume are paramount as suggested by the previous literature (4,5). Interventions to mitigate the trauma are effective and prognosis is generally good.

Reference
1- “Globe penetration in a cat following maxillary nerve block for dental surgery” R.Perry et al. J Feline Med Surg. 2014; 17(1):66-72

2- “Regional anaesthesia and analgesia for oral and dental procedure”. J.Rochette Vet Clin North Am Small Anim Pract 2005; 35: 1041-1058

3-“Severe cardiovascular depression in a cat following a mandibular nerve block with bupivacaine” F. Aprea et al. Vet Anaesth Analg 2011; 38: 614-618.
4-“Tongue lacerations in a geriatric dog after bilateral inferior alveolar nerve blocks with bupivacaine” A Y K Chau Veterinary Case Report 2017, 5(3):
5- “A Retrospective Study of the Incidence and Management of Complications Associated with Regional Nerve Blocks in Equine Dental Patients” R B Tunner; A E Hubbell JVD 2019, vol 36 (1)
6- BSVA Manual of canine and feline dentistry and oral surgery 4TH edition. A M Reiter and M Gracis. Chapter 6, pag 133.