Medication-related osteonecrosis of the jaw after long-term bisphosphonate treatment in a cat

A retrospective case series on bisphosphonate related osteonecrosis of the jaw in 20 cats

Introduction

This retrospective study highlights the salient aspects of a series of feline patients affected with bisphosphonate related osteonecrosis of the jaw. Though more commonly published in human literature, this presentation is rare in cats. The authors hope that this study will assist in making this a more globally known entity with subsequent improved prognosis.

Methods

Data was retrospectively obtained from the medical records between 2015 and 2021 of 20 cats with Medication Related Osteonecrosis of the Jaw. Data included patient information, clinical history, presenting complaint, systemic diseases, details referable to hypercalcemia and treatment thereof, bisphosphonate specifics (dose and duration), clinical presentation of the lesion, diagnostic testing including radiographic and histopathologic descriptions, treatment, and outcome.

Results

Pertinent results include that all 20 cats who developed Medication Related Osteonecrosis of the Jaw had been treated for idiopathic hypercalcemia with the bisphosphonate medication alendronate. Eighty-five percent of the cases had prior dental extractions at the site of MRONJ lesion. Ninety-five percent of the affected cats required a surgical procedure to control the disease. Thirty-five percent of cases required at least one revision surgery after the initial procedure was performed. 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.

Discussion

The case series reveals that cats with feline idiopathic hypercalcemia treated with 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. The authors have also included a relevant comparative literature review.

Assessment of alendronate and dietary treatment in the management of feline idiopathic ionised hypercalcaemia and ionised hypercalcaemia associated with chronic kidney disease: 29 cases (2016-2022)

OBJECTIVES

This retrospective cohort multicentre study aimed to characterise the signalment, clinicopathologic data, complications and the association between treatment and outcome (the reduction in ionised calcium concentration) in cats with idiopathic or chronic kidney disease-associated ionised hypercalcaemia managed with alendronate and standard treatment or standard treatment alone, and to compare the outcome between the two groups.

MATERIALS AND METHODS

Medical records for cats diagnosed with idiopathic or chronic kidney disease-associated ionised hypercalcaemia were retrospectively reviewed. Cats treated with alendronate and standard treatment were assigned to the alendronate group and cats treated with standard treatment alone were assigned to the control group. The standard treatment was defined as dietary modification and/or monitoring of ionised calcium concentrations and management of complications secondary to hypercalcaemia. The follow-up period was selected as 6 months.

RESULTS

Twenty-nine cats were enrolled in the study. Nine cats were included in the control group and 20 cats in the alendronate group. A significant reduction in serum ionised calcium was observed in both groups between the baseline and the follow-up visit; however, this reduction did not differ significantly between both groups (the mean change in the ionised calcium concentration in alendronate and control group was -0.18 and -0.17, respectively). Suspected bisphosphate-related osteonecrosis of the jaw was reported in one cat receiving alendronate.

CLINICAL SIGNIFICANCE

In this study, similar reduction in serum ionised calcium concentration was observed in cats with ionised hypercalcaemia treated with diet alone and in cats treated with diet and alendronate. These results should be interpreted with caution, as the study was underpowered for meaningful statistical comparison. Cats receiving alendronate should be monitored for the development of adverse reactions, including osteonecrosis of the jaw.

Clodronate disodium does not produce measurable effects on bone metabolism in an exercising, juvenile, large animal model

Bisphosphonates are commonly used to treat and prevent bone loss, but their effects in active, juvenile populations are unknown. This study examined the effects of intramuscular clodronate disodium (CLO) on bone turnover, serum bone biomarkers (SBB), bone mineral density (BMD), bone microstructure, biomechanical testing (BT), and cartilage glycosaminoglycan content (GAG) over 165 days. Forty juvenile sheep (253 ± 6 days of age) were divided into four groups: Control (saline), T0 (0.6 mg/kg CLO on day 0), T84 (0.6 mg/kg CLO on day 84), and T0+84 (0.6 mg/kg CLO on days 0 and 84). Sheep were exercised 4 days/week and underwent physical and lameness examinations every 14 days. Blood samples were collected for SBB every 28 days. Microstructure and BMD were calculated from tuber coxae (TC) biopsies (days 84 and 165) and bone healing was assessed by examining the prior biopsy site. BT and GAG were evaluated postmortem. Data, except lameness data, were analyzed using a mixed-effects model; lameness data were analyzed as ordinal data using a cumulative logistic model. CLO did not have any measurable effects on the skeleton of sheep. SBB showed changes over time (p ≤ 0.03), with increases in bone formation and decreases in some bone resorption markers. TC biopsies showed increasing bone volume fraction, trabecular spacing and thickness, and reduced trabecular number on day 165 versus day 84 (p ≤ 0.04). These changes may be attributed to exercise or growth. The absence of a treatment effect may be explained by the lower CLO dose used in large animals compared to humans. Further research is needed to examine whether low doses of bisphosphonates may be used in active juvenile populations for analgesia without evidence of bone changes.

Ionized hypercalcemia can resolve with nutritional modification in cats with idiopathic hypercalcemia or chronic kidney disease

CASE SERIES SUMMARY

Cats with ionized hypercalcemia that were fed diets with either more than 200 mg calcium per 100 kilocalories (kcal), a calcium:phosphorus (Ca:P) ratio greater than 1.4:1 or both, based on diet history, were included in this case series. Ionized hypercalcemia was documented at least twice in all cats before enrollment. Cats were referred for evaluation of ionized hypercalcemia (n = 5) or were incidentally found to have ionized hypercalcemia (n = 5). After medical workups, cats were diagnosed with either idiopathic hypercalcemia (IHC; n = 7) or chronic kidney disease (n = 3). Cats receiving medications to treat IHC (eg, alendronate, corticosteroids) were excluded. Nutritional recommendations were made to transition the cats to diets with less thn 200 mg calcium per 100 kcal and a Ca:P ratio less than 1.4:1. Ionized calcium (iCa) concentrations were rechecked in all cats, with a median recheck time of 9 weeks (range 3-20). Of the 10 cats, nine (90%) had a decrease in iCa. Of the 10 cats, six (60%) became normocalcemic after the diet change, three (30%) had a partial response and one (10%) did not respond. Of the four cats that did not achieve normocalcemia with a change in diet, two (50%) received chia seeds (1-2 g per day), and at the next recheck, both cats' iCa concentrations had normalized. Three cats had a long-term follow-up. Ionized normocalcemia was maintained for at least two consecutive follow-up visits over a median follow-up period of 33 weeks (range 12-34).

RELEVANCE AND NOVEL INFORMATION

Dietary calcium concentrations and the dietary Ca:P ratio appear to be important variables in considering nutritional approaches for hypercalcemic cats.

Characterization of Oral Pathology in Cats Affected by Patellar Fracture and Dental Anomaly Syndrome (PADS)

Patellar fracture and dental anomaly syndrome (PADS) is a congenital bone disease of cats that is characterized by atraumatic bone fractures (most commonly the patella), the persistence of deciduous teeth, and impaction of permanent teeth. Jaw swelling due to osteomyelitis is often the reason that cats with PADS are presented for veterinary dental care. The clinical history, oral examination findings, dental radiological findings, and histopathology were evaluated for 13 cats with dental and skeletal pathology consistent with PADS, including 9 with osteomyelitis. Cats in this study were predominantly domestic shorthair (12 of 13 cats), and there was no apparent sex predilection. All cats had multiple persistent deciduous teeth and multiple impacted permanent teeth, although the number of persistent and impacted teeth varied. Osteomyelitis of the jaw typically occurred within the first 4 years of life. Osteomyelitis of the mandible was 4 times more common than osteomyelitis of the maxilla. Histologically, osteomyelitis was chronic, neutrophilic, and osteoproliferative. Necrotic bone was confirmed in 67% of osteomyelitis lesions. Histological evaluation of jaws without inflammation demonstrated abnormal amounts of unmodeled bone, abnormally dense bone, and retention of cartilage in the caudal mandible. Three cats in the study had mandibular distoclusion and 2 had concurrent paronychia. To obtain a favorable clinical outcome in PADS cats with jaw swelling, prompt and aggressive surgical treatment of osteomyelitis is required. Extraction of persistent deciduous teeth and impacted permanent teeth is recommended when there is associated periodontitis or osteomyelitis.

Management of insufficiency fractures associated with long-term bisphosphonate therapy in a cat

Case summary

A 10-year-old spayed female domestic medium hair cat presented after sustaining atraumatic insufficiency fractures of the right calcaneus and the left tibia approximately 6 weeks apart. Chronic alendronate therapy had been ongoing for 9 years for the management of previously diagnosed idiopathic hypercalcemia. The right calcaneal fracture was managed non-operatively due to minimal functional impairment. The left tibial fracture was managed via open reduction and internal fixation with orthogonal plating. Alendronate therapy was discontinued at the time of the fracture repair with prednisolone being used to manage the hypercalcemia. Despite rapid clinical improvement, the tibial fracture had a protracted healing course, with clinical union only being achieved 22 weeks postoperatively. At 17 months postoperatively, the idiopathic hypercalcemia remained well controlled. Gait assessment, orthopedic examination and orthogonal radiographs performed at this time revealed resolution of left pelvic limb lameness, a normal orthopedic examination of the left pelvic limb and no evidence of implant-associated complications. Monitoring is ongoing but at the time of publication, no further fractures have occurred.

Relevance and novel information

As reported in humans, this case report gathers evidence of associations between bisphosphonate treatment and the occurrence of insufficiency fractures in cats, and provides evidence that stress reactions may precede their development. If bisphosphonate therapy is utilized in the long term, serial radiographic monitoring for signs of impending fracture may be warranted. Fracture repair can be successful in cats that have received long-term bisphosphonate therapy, but delayed healing should be anticipated and implant choices made accordingly.

Advent of phytobiologics and nano-interventions for bone remodeling: a comprehensive review

Bone metabolism constitutes the intricate processes of matrix deposition, mineralization, and resorption. Any imbalance in these processes leads to traumatic bone injuries and serious disease conditions. Therefore, bone remodeling plays a crucial role during the regeneration process maintaining the balance between osteoblastogenesis and osteoclastogenesis. Currently, numerous phytobiologics are emerging as the new therapeutics for the treatment of bone-related complications overcoming the synthetic drug-based side effects. They can either target osteoblasts, osteoclasts, or both through different mechanistic pathways for maintaining the bone remodeling process. Although phytobiologics have been widely used since tradition for the treatment of bone fractures recently, the research is accentuated toward the development of osteogenic phytobioactives, constituent-based drug designing models, and efficacious delivery of the phytobioactives. To achieve this, different plant extracts and successful isolation of their phytoconstituents are critical for osteogenic research. Hence, this review emphasizes the phytobioactives based research specifically enlisting the plants and their constituents used so far as bone therapeutics, their respective isolation procedures, and nanotechnological interventions in bone research. Also, the review enlists the vast array of folklore plants and the newly emerging nano-delivery systems in treating bone injuries as the future scope of research in the phytomedicinal orthopedic applications.

Alendronate treatment in cats with persistent ionized hypercalcemia: A retrospective cohort study of 20 cases

BACKGROUND

Limited information is available concerning treatment of ionized hypercalcemia in cats.

HYPOTHESIS/OBJECTIVES

Describe clinical findings in a cohort of cats with persistent ionized hypercalcemia and evaluate long-term tolerance and efficacy of alendronate in these patients.

ANIMALS

Twenty cats with persistent ionized hypercalcemia of undetermined origin, presented for routine or referral consultation at the teaching hospital of Maisons-Alfort (France).

METHODS

Medical records were retrospectively reviewed. Cats were divided into Group 1 (cats that received alendronate as well as other treatments, n = 11) and Group 2 (cats that did not receive alendronate, n = 9). Survival analysis (Kaplan-Meier method, log-rank test, and Cox proportional hazard models) was conducted to compare time to selected outcomes.

RESULTS

Azotemia was present in 15 cats (75%). Alendronate treatment was administered and well tolerated during the entire follow-up period (median, 9.5 months; interquartile range [IQR], 6.3; 27) in all cats from Group 1, except in 1 cat that developed severe hypophosphatemia, prompting treatment discontinuation. Univariate analysis determined that alendronate treatment was significantly associated with shorter time to reach a 15% decrease in ionized calcium concentration (iCa) from baseline during follow-up (119 days vs median not reached, P = .02). This association was no longer significant after adjustment for age and initial iCa.

CONCLUSIONS AND CLINICAL IMPORTANCE

Alendronate overall was well tolerated with chronic use in this cohort, and can be considered a treatment option for persistent ionized hypercalcemia in cats.

Is the Use of Bisphosphonates Putting Horses at Risk? An Osteoclast Perspective

Simple Summary

Bisphosphonates are a group of drugs that intervene in the bone resorption process, producing cellular death of osteoclasts. These drugs are used for skeletal conditions, such as osteoporosis in humans, and are available for veterinary medical use. Clodronate and tiludronate are bisphosphonates approved for the treatment of navicular syndrome in horses over four years old. However, these drugs are sometimes used in juvenile animals under exercise, where osteoclast activity is higher. Bisphosphonate use in juvenile and/or exercising animals could have adverse effects, including maladaptation to exercise or accumulation of microdamage. Furthermore, bisphosphonates can be bound to the skeleton for several years, resulting in a prolonged effect with no pharmaceutical reversal available. This review presents an overview of osteoclast function and a review of bisphosphonate characteristics, mechanisms of action, and side effects in order to contextualize the potential for adverse/side effects in young or exercising animals.

Abstract

Osteoclasts are unique and vital bone cells involved in bone turnover. These cells are active throughout the individual’s life and play an intricate role in growth and remodeling. However, extra-label bisphosphonate use may impair osteoclast function, which could result in skeletal microdamage and impaired healing without commonly associated pain, affecting bone remodeling, fracture healing, and growth. These effects could be heightened when administered to growing and exercising animals. Bisphosphonates (BPs) are unevenly distributed in the skeleton; blood supply and bone turnover rate determine BPs uptake in bone. Currently, there is a critical gap in scientific knowledge surrounding the biological impacts of BP use in exercising animals under two years old. This may have significant welfare ramifications for growing and exercising equids. Therefore, future research should investigate the effects of these drugs on skeletally immature horses.

Vitamin D metabolism and disorders in dogs and cats

Vitamin D plays an important role in regulating calcium metabolism and in the development and maintenance of skeletal health of companion animals. There is also a growing interest in understanding the role vitamin D plays in non-skeletal health in both human and veterinary patients. This review provides an update of our current understanding of vitamin D biology in dogs and cats and gives an overview of how vitamin D metabolism can be assessed in companion animals. Congenital and acquired vitamin D disorders are then summarised before the review concludes with a summary of recent studies which have explored the role of vitamin D in the development and outcomes of non-skeletal diseases of dogs and cats.

Bisphosphonates in veterinary medicine: The new horizon for use

Bisphosphonates (BPs) are characterized by their ability to bind strongly to bone mineral and inhibit bone resorption. However, BPs exert a wide range of pharmacological activities beyond the inhibition of bone resorption, including the inhibition of cancer cell metastases and angiogenesis and the inhibition of proliferation and apoptosis in vitro. Additionally, the inhibition of matrix metalloproteinase activity, altered cytokine and growth factor expression, as well as reductions in parameters of pain have also been reported. In humans, clinical BP use has transformed the treatment of post-menopausal osteoporosis, rare bone diseases such as osteogenesis imperfecta, as well as multiple myeloma and metastatic breast and prostate cancer, albeit not without infrequent but significant adverse events. Despite the well-characterized health benefits of BP use in humans, the evidence-base for the therapeutic efficacy of BPs in veterinary medicine is, by comparison, limited. Notwithstanding, BPs are used widely in small animal veterinary practice for the medical management of hyperparathyroidism, idiopathic hypercalcemia in cats, as well as for the palliative care of bone tumors which are common in dogs, and in particular, primary bone tumors such as osteosarcoma. Palliative BP treatment has also recently increased in veterinary oncology to alleviate tumor-associated bone pain. In equine veterinary practice, non-nitrogen-containing BPs are FDA-approved to control clinical signs associated with navicular syndrome in adult horses. However, there are growing concerns regarding the off-label use of BPs in juvenile horses. Here we discuss the current understanding of the strengths, weaknesses and current controversies surrounding BP use in veterinary medicine to highlight the future utility of these potentially beneficial drugs.

Mitigating osteonecrosis of the jaw (ONJ) through preventive dental care and understanding of risk factors

It is well established that alterations in phosphate metabolism have a profound effect on hard and soft tissues of the oral cavity. The present-day clinical form of osteonecrosis of the jaw (ONJ) was preceded by phosphorus necrosis of the jaw, ca. 1860. The subsequent removal of yellow phosphorus from matches in the early 20th century saw a parallel decline in "phossy jaw" until the early 2000s, when similar reports of unusual jaw bone necrosis began to appear in the literature describing jaw necrosis in patients undergoing chemotherapy and concomitant steroid and bisphosphonate treatment. Today, the potential side effect of ONJ associated with medications that block osteoclast activity (antiresorptive) is well known, though the mechanism remains unclear and the management and outcomes are often unsatisfactory. Much of the existing literature has focused on the continuing concerns of appropriate use of bisphosphonates and other antiresorptive medications, the incomplete or underdeveloped research on ONJ, and the use of drugs with anabolic potential for treatment of osteoporosis. While recognizing that ONJ is a rare occurrence and ONJ-associated medications play an important role in fracture risk reduction in osteoporotic patients, evidence to date suggests that health care providers can lower the risk further by dental evaluations and care prior to initiating antiresorptive therapies and by monitoring dental health during and after treatment. This review describes the current clinical management guidelines for ONJ, the critical role of dental-medical management in mitigating risks, and the current understanding of the effects of predominantly osteoclast-modulating drugs on bone homeostasis.

Medication-related osteonecrosis of the jaw after long-term bisphosphonate treatment in a cat

A 12‐year‐old, neutered female, domestic medium hair cat was evaluated for a nonhealing, oral mucosal ulceration. The cat had a history of idiopathic hypercalcemia that had been treated with a bisphosphonate for 41 months. Oral examination identified exposed maxillary bone adjacent to a previous extraction site. Histopathology of the exposed bone and associated mucosa was most consistent with medication‐related osteonecrosis of the jaw. Treatment involved both medical and surgical interventions. Oral mucosal healing occurred after 6 months of treatment.