Tiludronate as a new therapeutic agent in the treatment of navicular disease: a double-blind placebo-controlled clinical trial

Clinically relevant doses of tiludronate do not affect bone remodelling in pasture-exercised horses

BACKGROUND

Bisphosphonates are widely used in equine athletes to reduce lameness associated with skeletal disorders. Widespread off-label use has led to concern regarding potential negative effects on bone healing, but little evidence exists to support or refute this.

OBJECTIVES

To investigate the influence of clinically relevant doses of tiludronate on bone remodelling and bone healing.

STUDY DESIGN

Randomised, controlled in vivo experiments.

METHODS

Each horse had a single tuber coxae biopsied (Day 0), then were divided into a treatment (IV tiludronate) or control (IV saline) group. Treatments were administered 30 and 90 days following initial biopsy. Biopsy of the tuber coxae was repeated on Day 60 to evaluate bone healing following a single treatment. Oxytetracycline was administered on Days 137 and 147 to label bone formation. The contralateral tuber coxae was biopsied on Day 150 to evaluate effects of repeated treatment. Bone biopsies were evaluated with micro-computed tomography and/or dynamic histomorphometry using standard techniques.

RESULTS

Nineteen horses completed the study, with no complications following the biopsies and treatments. No significant differences in the trabecular bone parameters or bone formation rate were observed between treatment groups.

MAIN LIMITATIONS

The use of a first-generation bisphosphonate may mean some effects of these drugs are underrepresented using this model. The results pertain to the tuber coxae and may not reflect injury or the healing response that occurs in long bones in training or racing.

CONCLUSIONS

In this model, tiludronate did not affect normal bone remodelling in the horse, despite repeat dosages.

Effect of clodronate on gene expression in the peripheral blood of horses

There are two FDA-approved bisphosphonate products, clodronate (Osphos®) and tiludronate (Tildren®), for use in horses. It is hypothesized that bisphosphonates can produce analgesic effects and prevent proper healing of microcracks in bone. Therefore, bisphosphonate use is banned in racehorses. However, bisphosphonates have a short detection window in the blood before sequestration in the skeleton, making the reliability of current drug tests questionable. Seven exercising Thoroughbred horses were administered clodronate (1.8 mg/kg i.m.), and four were administered saline. RNA was isolated from peripheral blood mononuclear cells (PBMCs) collected immediately before a single dose of clodronate or saline and then on Days 1, 6, 28, 56 and 182 post-dose. mRNA was sequenced and analysed for differentially expressed transcripts. While no single transcripts were differentially expressed, pathway analysis revealed that p38 MAPK (p = .04) and Ras (p = .04) pathways were upregulated, and cadherin signalling (p = .02) was downregulated on Day 1. Previously investigated biomarkers, cathepsin K (CTSK) and type 5 acid phosphatase (ACP5), were analysed with RT-qPCR in a targeted gene approach, with no significant difference observed. A significant effect of time on gene expression for ACP5 (p = .03) and CTSK (p < .0001) was observed. Thus, these genes warrant further investigation for detecting clodronate use over time.

Equine Musculoskeletal Pathologies: Clinical Approaches and Therapeutical Perspectives-A Review

Musculoskeletal injuries such as equine osteoarthritis, osteoarticular defects, tendonitis/desmitis, and muscular disorders are prevalent among sport horses, with a fair prognosis for returning to exercise or previous performance levels. The field of equine medicine has witnessed rapid and fruitful development, resulting in a diverse range of therapeutic options for musculoskeletal problems. Staying abreast of these advancements can be challenging, prompting the need for a comprehensive review of commonly used and recent treatments. The aim is to compile current therapeutic options for managing these injuries, spanning from simple to complex physiotherapy techniques, conservative treatments including steroidal and non-steroidal anti-inflammatory drugs, hyaluronic acid, polysulfated glycosaminoglycans, pentosan polysulfate, and polyacrylamides, to promising regenerative therapies such as hemoderivatives and stem cell-based therapies. Each therapeutic modality is scrutinized for its benefits, limitations, and potential synergistic actions to facilitate their most effective application for the intended healing/regeneration of the injured tissue/organ and subsequent patient recovery. While stem cell-based therapies have emerged as particularly promising for equine musculoskeletal injuries, a multidisciplinary approach is underscored throughout the discussion, emphasizing the importance of considering various therapeutic modalities in tandem.

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.

Clodronate disodium is neither cytotoxic nor cytoprotective to normal and recombinant equine interleukin-1β-treated joint tissues in vitro

OBJECTIVE

To determine the effects of clodronate disodium (CLO) on control and recombinant equine interleukin-1β (IL-1β)-treated equine joint tissues.

STUDY DESIGN

In vitro experimental study.

SAMPLE POPULATION

Cartilage explants, chondrocytes, and synoviocytes (n = 3 horses).

METHODS

Monolayer cultures of chondrocytes and synoviocytes from three horses were subjected to: control media (CON), 5 ng/ml CLO (C/low), 50 ng/ml CLO (C/med), 100 ng/ml CLO (C/high), with and without IL-1β, and 10 ng/ml IL-1β (IL) alone for 72 hours. Cartilage explants from three horses were subjected to CON, IL, C/low, and C/med with and without IL-1β for 72 hours. Culture media was analyzed for prostaglandin-E₂ (PGE₂ ), interleukin-6 (IL-6), and nitric oxide (NO). Explant media was analyzed for glycosaminoglycan (GAG) content and NO. At 72 hours, explant and monolayer culture viability were assessed, and explant GAG content was measured.

RESULTS

IL-1β treatment resulted in higher media concentrations of GAG, NO, PGE₂ , and IL-6 compared to the CON treatment (p < .05), demonstrating a catabolic effect of IL-1β on explants and monolayer cultures. CLO treatments did not increase media concentrations of GAG, NO, PGE₂ , or IL-6 compared to CON, indicating no cytotoxic effect. Nevertheless, CLO treatments administered to IL-1β-treated monolayer cultures and explants did not significantly reduce the inflammatory response regardless of concentration.

CONCLUSION

CLO did not demonstrate cytotoxic nor cytoprotective effects in normal and IL-1β-stimulated chondrocytes, synoviocytes or explants in culture.

CLINICAL SIGNIFICANCE

This study does not support the use of CLO as an anti-inflammatory treatment. Further research is necessary to confirm any anti-inflammatory effects of CLO on joint tissues.

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.

Other Clinical Problems of the Equine Foot

Many disorders affect the equine foot, and many hoof problems have multiple predisposing causes. Surgery may be necessary after conservative management has failed. Diseases of the hoof capsule may seem simple, but their effect on performance can be long-lasting and healing is often prolonged. Diagnosis of problems within the hoof capsule is enhanced with the use of computed tomography and MRI. The prognosis of fractures has improved with strategic placement of lag screws across fracture planes using aiming devices and advanced intraoperative imaging techniques. Collaboration between the clinician and a skilled farrier is important for successful management of hoof disorders.

Effect of intravenous tiludronate disodium administration on the radiographic progression of osteoarthritis of the fetlock joint in Standardbred racehorses

OBJECTIVE

To compare the effects of tiludronate disodium and 3 other medical treatments on clinical and radiographic findings and biomarkers of disease progression in horses with osteoarthritis of the fetlock joint.

ANIMALS

100 Standardbred racehorses with spontaneous traumatic injury of the fetlock joint.

PROCEDURES

Horses were retrospectively grouped by whether they received tiludronate IV or triamcinolone acetonide and hyaluronan, polysulfated glycosaminoglycan, or interleukin-1 receptor antagonist protein intra-articularly. Data were collected on clinical, radiographic, and ultrasonographic findings and results for serum and synovial samples obtained before and 6 months after treatment. Lameness score, joint flexion test response, radiographic score, serum concentrations of tumor necrosis factor-α and carboxy-terminal telopeptides of collagen types I and II (CTX-I and II, respectively), and synovial fluid concentrations of interleukin-1β, prostaglandin E₂, and CTX-II were compared among treatments.

RESULTS

All treatments resulted in a significant improvement in lameness score and joint flexion test response at 6 months. In horses that received triamcinolone acetonide and hyaluronan, synovial fluid interleukin-1β, prostaglandin E₂, and CTX-II concentrations decreased after treatment, suggesting this treatment inhibited progression of hyaline cartilage degeneration and inflammatory processes. Horses that received tiludronate were the only group that had a decrease in radiographic score and serum CTX-I concentration after treatment, supporting the effect of tiludronate on bone metabolism. Tiludronate treatment was also followed by increases in serum and synovial fluid concentrations of CTX-II, a marker of cartilage damage.

CONCLUSIONS AND CLINICAL RELEVANCE

Tiludronate appeared to inhibit the radiographic progression of osteoarthritis in high-motion joints of racehorses at 6 months after treatment by inhibiting subchondral bone remodeling. Whether this effect was associated with a worsening of progressive cartilage damage remains to be ascertained.

The equine navicular apparatus as a premier enthesis organ: Functional implications

Navicular syndrome has been traditionally characterized by progressive lameness with chronic degeneration of the navicular bone. Advances in imaging techniques have revealed that its associated soft tissue structures are also affected. This distribution of lesions is explained by conceptualizing the equine navicular apparatus as an enthesis organ that facilitates the dissemination of mechanical stress throughout the tissues of the foot. The navicular apparatus has the same structural adaptations to mechanical stress as the human Achilles tendon complex. These adaptations efficiently dissipate mechanical force away from the tendon's bony attachment site, thereby protecting it from failure. The comparison of these two anatomically distinct structural systems demonstrates their similar adaptations to mechanical forces, and illustrates that important functional insights can be gained from studying anatomic convergences and cross-species comparisons of function. Such a functional conceptualization of the equine navicular apparatus resolves confusion about the diagnosis of navicular syndrome and offers insights for the development of mechanically based therapies. Through comparison with the human Achilles complex, this review (1) re-conceptualizes the equine navicular apparatus as an enthesis organ in which mechanical forces are distributed throughout the structures of the organ; (2) describes the relationship between failure of the navicular enthesis organ and lesions of navicular syndrome; (3) considers the therapeutic implications of navicular enthesis organ degeneration as a form of chronic osteoarthritis; and based upon these implications (4) proposes a focus on whole body posture/motion for the development of prehabilitative and rehabilitative therapies similar to those that have already proven effective in humans.

Doping detection in animals: A review of analytical methodologies published from 1990 to 2019

Despite the impressive innate physical abilities of horses, camels, greyhounds, or pigeons, doping agents might be administered to these animals to improve their performance. To control these illegal practices, anti-doping analytical methodologies have been developed. This review compiles the analytical methods that have been published for the detection of prohibited substances administered to animals involved in sports over 30 years. Relevant papers meeting the search criteria that discussed analytical methods aiming to detect and/or quantify doping substances in animal biological matrices published from 1990 to 2019 were considered. A total of 317 studies were included, of which 298 were related to horses, demonstrating significant advances toward the development of doping detection methods for equine sports. However, analytical methods for the detection of doping agents in sports involving other species are lacking. Due to enhanced accuracy and specificity, chromatographic analysis coupled to mass spectrometry detection is preferred over immunoassays. Regarding biological matrices, blood and urine remain the first choice, although alternative biological matrices, such as hair and feces, have been considered. With the increasing number and type of drugs used as doping agents, the analytes addressed in the published papers are diverse. It is very important to continue to detect and quantify these drugs, recognizing those that are most frequently used, in order to punish the abusers, protect animals' health, and ensure a healthier and genuine competition.

Development and Clinical Application of Phosphorus-Containing Drugs

Phosphorus-containing drugs belong to an important class of therapeutic agents and are widely applied in daily clinical practices. Structurally, the phosphorus-containing drugs can be classified into phosphotriesters, phosphonates, phosphinates, phosphine oxides, phosphoric amides, bisphosphonates, phosphoric anhydrides, and others; functionally, they are often designed as prodrugs with improved selectivity and bioavailability, reduced side effects and toxicity, or biomolecule analogues with endogenous materials and antagonistic endoenzyme supplements. This review summarized the phosphorus-containing drugs currently on the market as well as a few promising molecules at clinical studies, with particular emphasis on their structural features, biological mechanism, and indications.

Pharmacokinetics and pharmacodynamics of clodronate disodium evaluated in plasma, synovial fluid and urine

BACKGROUND

Clodronate is a non-nitrogenated bisphosphonate approved for use in horses. There are no peer-reviewed published reports describing the pharmacokinetics or evaluating renal health indices and urinary excretion patterns in conjunction with plasma and synovial fluid concentration following the systemic administration of clodronate to horses.

OBJECTIVES

Describe clodronate concentrations in plasma, urine and synovial fluid and evaluate the effects on renal indices after intramuscular administration to healthy horses.

STUDY DESIGN

Experimental study with repeated measures.

METHODS

Six healthy adult horses received a single intramuscular dose of clodronate (1.8 mg/kg). Blood, synovial fluid and urine were collected prior to and after administration of clodronate up to 72, 48 and 168 hours respectively. Drug concentrations were measured using LC-MS/MS and noncompartmental pharmacokinetic analysis was performed. Renal function indices were also evaluated.

RESULTS

Clodronate was quantifiable for up to 24 hours in plasma and 48 hours in synovial fluid and detected at all time points in urine. Maximum plasma concentration of clodronate 210 ± 68.2 ng/mL occurred at approximately 34.8 ± 0.2 minutes after administration, while peak synovial concentration (57.7 ± 32.8 ng/mL) occurred at 2.67 ± 2.32 hours after administration and peak urine concentration (88 358.2 ± 79 521.4 ng/mL) occurred at 2.67 ± 2.58 hours post administration. Terminal half-life in plasma was 3.32 ± 1.25 and was 4.8 ± 3.05 hours in synovial fluid. Creatinine concentrations rose significantly after treatment but remained within normal adult reference ranges at all times.

MAIN LIMITATIONS

Limited number of animals and sampling times and the absence of urine collection for determination of concentration beyond 7 days.

CONCLUSIONS

Clodronate is rapidly cleared from the blood and synovial fluid. It has variable and biphasic urinary excretion. While significant increase in blood creatinine concentrations was present after a single intramuscular dose of clodronate, values were never above the normal reference range. Further studies are warranted in horses undergoing exercise and those undergoing multiple dosing schemes.

Clinical efficacy of clodronic acid in horses diagnosed with navicular syndrome: A field study using objective and subjective lameness evaluation

Navicular syndrome, a common cause of equine forelimb lameness, is associated with pathological changes in the navicular bone. Consequently, administration of bisphosphonates (BPs) has been advocated in order to modify the rate of bone turnover. The present study aimed to assess the clinical efficacy of intramuscularly administered clodronic acid for the treatment of 11 horses with clinical and radiographic findings compatible with navicular syndrome. Magnetic resonance imaging was performed in 5 of the 11 horses. The animals were treated with an intramuscular dose of clodronic acid of 765 mg/horse, administered over three separate injection sites. Before and at 7, 30 and 90 days after treatment, horses were subjected to lameness and accelerometric evaluations. A clinical improvement was observed in 6 of the 11 horses. These 6 horses showed a mean reduction of two degrees in lameness score. Accelerometry in these horses revealed increased velocity, stride length, stride regularity and dorsoventral displacement of the gravity of centre together with a reduction in stride frequency, suggesting a gait improvement. This study demonstrates that intramuscular clodronic acid can be useful for lameness reduction in some horses with navicular syndrome.

Bisphosphonate use in the horse: what is good and what is not?

Background

Bisphosphonates (BPs) are a family of molecules characterized by two key properties: their ability to bind strongly to bone mineral and their inhibitory effects on mature osteoclasts and thus bone resorption. Chemically two groups of BPs are recognized, non-nitrogen-containing and nitrogen-containing BPs. Non-nitrogen-containing BPs incorporate into the energy pathways of the osteoclast, resulting in disrupted cellular energy metabolism leading to cytotoxic effects and osteoclast apoptosis. Nitrogen-containing BPs primarily inhibit cholesterol biosynthesis resulting in the disruption of intracellular signaling, and other cellular processes in the osteoclast.

Body

BPs also exert a wide range of physiologic activities beyond merely the inhibition of bone resorption. Indeed, the breadth of reported activities include inhibition of cancer cell metastases, proliferation and apoptosis in vitro. In addition, the inhibition of angiogenesis, matrix metalloproteinase activity, altered cytokine and growth factor expression, and reductions in pain have been reported. In humans, clinical BP use has transformed the treatment of both post-menopausal osteoporosis and metastatic breast and prostate cancer. However, BP use has also resulted in significant adverse events including acute-phase reactions, esophagitis, gastritis, and an association with very infrequent atypical femoral fractures (AFF) and osteonecrosis of the jaw (ONJ).

Conclusion

Despite the well-characterized health benefits of BP use in humans, little is known regarding the effects of BPs in the horse. In the equine setting, only non-nitrogen-containing BPs are FDA-approved primarily for the treatment of navicular syndrome. The focus here is to discuss the current understanding of the strengths and weaknesses of BPs in equine veterinary medicine and highlight the future utility of these potentially highly beneficial drugs.

Recent advances in conservative and surgical treatment options of common equine foot problems

Foot problems are very common causes of lameness in horses. With the recent diagnostic advances to evaluate and treat foot pathology as well as to monitor response to therapy, it is now possible to more accurately evaluate the effectiveness of many of these treatments. This review details some of the recent advances of the most common conservative and surgical treatment options for foot problems in horses, including an overview of evidence on the efficacy to support the use of these treatment options and on factors that may affect prognosis.

Nutritional secondary hyperparathyroidism in two ponies

Nutritional secondary hyperparathyroidism (NSH) is uncommon in horses. Aim of this report is evaluate an alternative therapeutic approach and provide more information on the diagnostic procedures, through detailed microscopic findings of the bone lesions pony with NSH. Administration of tiludronate along with a balanced diet can be used in a treatment protocol for ponies with NSH. This case report suggests that tiludronate can be used to ameliorate the clinical signs of NSH.

Tiludronate and clodronate do not affect bone structure or remodeling kinetics over a 60 day randomized trial

Background

Tiludronate and clodronate are FDA-approved bisphosphonate drug therapies for navicular disease in horses. Although clinical studies have determined their ability to reduce lameness associated with skeletal disorders in horses, data regarding the effect on bone structure and remodeling is lacking. Additionally, due to off-label use of these drugs in young performance horses, effects on bone in young horses need to be investigated. Therefore, the purpose of this randomized, experimental pilot study was to determine the effect of tiludronate and clodronate on normal bone cells, structure and remodeling after 60 days in clinically normal, young horses. Additionally, the effect of clodronate on bone healing 60 days after an induced defect was investigated.

Results

All horses tolerated surgery well, with no post-surgery lameness and all acquired biopsies being adequate for analyses. Overall, tiludronate and clodronate did not significantly alter any bone structure or remodeling parameters, as evaluated by microCT and dynamic histomorphometry. Tiludronate did not extensively impact bone formation or resorption parameters as evaluated by static histomorphometry. Similarly, clodronate did not affect bone formation or resorption after 60 days. Sixty days post-defect, healing was minimally affected by clodronate.

Conclusions

Tiludronate and clodronate do not appear to significantly impact bone tissue on a structural or cellular level using standard dose and administration schedules.

Signal changes in standing magnetic resonance imaging of osseous injury at the origin of the suspensory ligament in four Thoroughbred racehorses under tiludronic acid treatment

Problems associated with the proximal metacarpal region, such as an osseous injury associated with tearing of Sharpey’s fibers or an avulsion fracture of the origin of the suspensory ligament (OISL), are important causes of lameness in racehorses. In the present study, four Thoroughbred racehorses (age range, 2–4 years) were diagnosed as having forelimb OISL and assessed over time by using standing magnetic resonance imaging (sMRI). At the first sMRI examination, all horses had 3 characteristic findings, including low signal intensity within the trabecular bone of the third metacarpus on T1-weighted images, intermediate-to-high signal intensity surrounded by a hypointense rim on T2*-weighted images, and high signal intensity on fat-suppressed images. Following the sMRI examination, all horses received 50 mg of tiludronic acid by intravenous regional limb perfusion once weekly for 3 weeks. Attenuation of the high signal intensity on T2*-weighted and fat-suppressed images was observed on follow-up sMRI in 3 horses. Following rest and rehabilitation, these 3 horses successfully returned to racing. In contrast, the other horse that did not show attenuation of the high signal intensity failed to return to racing. To our knowledge, this is the first report of OISL in Thoroughbred racehorses assessed over time by sMRI under tiludronic acid treatment. Our findings support the use of sMRI for examining lameness originating from the proximal metacarpal region to refine the timing of returning to exercise based on follow-up examinations during the recuperation period.

Tiludronate concentrations and cytologic findings in synovial fluid after intravenous regional limb perfusion with tiludronate in horses

Anecdotal accounts of tiludronate administration via intravenous regional limb perfusion (IVRLP) exist despite a lack of information regarding safety for synovial structures in the perfused area. The objective of this study was to determine whether tiludronate concentrations in synovial structures after IVRLP with low dose (0.5 mg, LDT) or high dose (50 mg, HDT) tiludronate remain below a value demonstrated in vitro to be safe for articular cartilage (<19,000 ng/ml), and to determine effects of tiludronate on synovial fluid cytology variables compared to saline perfused control limbs. Using a randomized controlled experimental study design, horses received IVRLP with LDT (n = 6) or HDT (n = 6) in one forelimb and IVRLP with saline in the contralateral limb. Synovial fluid cytology variables and tiludronate concentrations were evaluated in navicular bursae (NB), and distal interphalangeal (DIP) and metacarpophalangeal (MCP) joints one week before and 30-45 min after IVRLP, and in DIP and MCP joints 24 h after IVRLP. Data were analyzed with 2-way rmANOVA (p < 0.05). Highest measured synovial fluid tiludronate concentrations occurred 30-45 min post-perfusion. Mean tiludronate concentrations were lower in LDT limbs (MCP = 39.6 ± 14.3 ng/ml, DIP = 118.1 ± 66.6 ng/ml, NB = 82.1 ± 30.2 ng/ml) than in HDT limbs (MCP = 3,745.1 ± 1,536.6 ng/ml, DIP = 16,274.0 ± 5,460.2 ng/ml, NB = 6,049.3 ± 1,931.7 ng/ml). Tiludronate concentration was >19,000 ng/ml in DIP joints of two HDT limbs. Tiludronate was measurable only in synovial fluid from HDT limbs 24 h post-perfusion. There were no differences in synovial fluid cytology variables between control and treated limbs. Conclusions. In some horses, IVRLP with HDT may result in synovial fluid concentrations of tiludronate that may have adverse effects on articular cartilage, based on in vitro data. IVRLP with LDT is unlikely to promote articular cartilage degradation. Further studies to determine a safe and effective dose for IVRLP with tiludronate are needed.

Effects of low and high dose intraarticular tiludronate on synovial fluid and clinical variables in healthy horses-a preliminary investigation

To determine effects of intraarticularly administered tiludronate on articular cartilage in vivo, eight healthy horses were injected once with tiludronate (low dose tiludronate [LDT] 0.017 mg, n = 4; high dose tiludronate [HDT] 50 mg, n = 4) into one middle carpal joint and with saline into the contralateral joint. Arthrocentesis of both middle carpal joints was performed pre-treatment, and 10 min, 24 h, 48 h, 7 and 14 days after treatment. Synovial nucleated cell counts and total solids, tiludronate, sulfated glycosaminoglycan (sGAG), chondroitin sulfate 846 epitope (CS-846, a measure of aggrecan synthesis), and collagen type II cleavage neoepitope (C2C) concentrations were determined. Histologic analysis of joint tissues and sGAG quantitation in cartilage was performed at 14 days in HDT horses. Data were analyzed by repeated measures non-parametric ANOVA and Wilcoxon signed-rank test. High dose tiludronate administration produced synovial fluid tiludronate concentrations of 2,677,500 ng/mL, exceeding concentrations that were safe for cartilage in vitro, and LDT administration produced synovial fluid concentrations of 1,353 ng/mL, remaining below concentrations considered potentially detrimental to cartilage. With HDT, synovial fluid total solids concentration was higher at 24 h and 7 days and sGAG concentration was higher at 48 h, compared to control joints. Synovial fluid CS-846 concentration was increased over pre-treatment values in HDT control but not in HDT treated joints at 24 and 48 h. All joints (HDT and LDT control and treated) showed a temporary decrease in synovial fluid C2C concentration, compared to pre-treatment values. Histologic features of articular cartilage and synovial membrane did not differ between HDT treated and control joints. High dose tiludronate treatment caused a transient increase in synovial total solids and temporarily increased proteoglycan degradation in cartilage. Although clinical significance of these changes are questionable, as they did not result in articular cartilage damage, further investigation of the safety of intraarticular HDT in a larger number of horses is warranted.

Effects of intrabursal administration of botulinum toxin type B on lameness in horses with degenerative injury to the podotrochlear apparatus

OBJECTIVE

To determine the safety and short-term efficacy of intrabursal administration of botulinum toxin type B (BTXB) to alleviate lameness in horses with degenerative injury to the podotrochlear apparatus (PA).

ANIMALS

10 Quarter Horses with degenerative injury to the PA.

PROCEDURES

Degenerative injury to the PA was confirmed with diagnostic analgesia and imaging. Then, BTXB (3.8 to 4.5 U/kg) was injected into the podotrochlear (navicular) bursa of each horse. Three horses were used in a safety evaluation. Subsequently, video recordings of lameness evaluations were obtained for 7 client-owned horses 5 days before (baseline) and 7 and 14 days after BTXB treatment and used to determine the effect of BTXB injection on lameness; 1 horse was removed from the study 8 days after BTXB treatment. Three investigators who were unaware of the treated forelimbs or time points separately reviewed the recordings and graded the lameness of both forelimbs of the horses.

RESULTS

Improvement in lameness of the treated forelimbs was detected at 1 or both time points after BTXB administration in all horses. However, all horses had some degree of lameness at the end of the study. Two horses developed transient increases in lameness 48 to 72 hours after treatment; lameness resolved uneventfully.

CONCLUSIONS AND CLINICAL RELEVANCE

Intrabursal injection of BTXB temporarily alleviated chronic lameness in horses with degenerative injury to the PA, without causing serious short-term adverse effects. Further investigation into the potential use of BTXB in horses affected by degenerative injury to the PA is warranted.

Steroid diffusion into the navicular bursa occurs in horses affected by palmar foot pain

Palmar foot pain is frequently treated by steroid injections into the distal interphalangeal joint (DIPJ) in the anticipation that the steroid will diffuse to the navicular bursa and palmar foot structures. The object of this study was to determine if triamcinolone acetonide (TA) would in fact be able to locally diffuse from the DIPJ into the navicular bursa in horses affected by palmar foot pain. Both forelimb DIPJs (nine horses) were injected with 10 mg of TA. Navicular bursa fluid samples, both forelimb and one hind limb (systemic control), were analysed for TA with high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) six hours later. Foot radiographs were graded (0-4) on severity of changes. Forelimb navicular bursa TA concentrations (mean±sd log(10), 3.20±0.56) were significantly higher than systemic control concentrations (mean±sd log(10), 1.89±0.3) (P<0.0001). Horses with a radiographic grade of >2 were four times as likely to have TA log(10) concentrations less than 3.2 (158.49 ng/ml). TA locally diffused from the DIPJ into the navicular bursa in horses affected by palmar foot pain; TA concentrations decreased as radiographic severity increased.

Tiludronate infusion in the treatment of bone spavin: a double blind placebo-controlled trial

REASONS FOR PERFORMING STUDY

Tiludronate regulates bone remodelling through a decrease of the resorptive process and should therefore ameliorate the remodelling processes active in osteoarthritis of the distal tarsal joints ('bone spavin') and alleviate pain associated with abnormal bone lysis.

OBJECTIVE

To confirm the efficacy of tiludronate, administered as a single infusion at a dose of 1 mg/kg bwt, in the treatment of bone spavin in the horse.

METHODS

A double blind placebo controlled trial on 108 clinical cases of bone spavin was undertaken. The lameness score of the lamest limb was assessed following distal tarsal analgesia of the contralateral limb and followed-up using the same procedure throughout the study. Bone spavin in the lamest limb was confirmed by distal tarsal analgesia and radiography. Horses were treated at Day 0 and reassessed 60 days later after controlled exercise. A second nonblinded treatment was given to unresponsive horses and all horses were re-examined at Day 120. Exercise levels were recorded at each examination.

RESULTS

Eighty-seven horses completed the trial as per the protocol. The tiludronate horses were significantly less lame than the placebo horses (P = 0.0318). Horses treated at Day 60 with tiludronate showed further improvement in lameness at Day 120 (P = 0.0096 and P = 0.0034 for horses treated with tiludronate and placebo at Day 0, respectively). The only significant difference in radiographic findings between tiludronate and placebo was for presence of periarticular osteophytes (P = 0.006).

CONCLUSIONS

Tiludronate treatment is proven to be effective in bone spavin in horses in association with a controlled exercise programme.

CLINICAL RELEVANCE

Tiludronate in combination with controlled exercise offers an alternate medical treatment for bone spavin.

Outcome of medical treatment for horses with foot pain: 56 cases

REASONS FOR PERFORMING STUDY

Currently, there are limited data regarding the long-term outcome of horses with foot pain treated with corrective shoeing, rest and rehabilitation, and intrasynovial anti-inflammatory medication to target lesions detected with MRI.

OBJECTIVE

To report the long-term (≥12 months) outcome of horses with foot lesions following medical therapy.

HYPOTHESES

1) There is no association between clinical parameters considered and a poor response to therapy. 2) Horses with a deep digital flexor tendinopathy are less likely to respond to medical therapy than horses without a deep digital flexor tendinopathy.

METHODS

The medical records of horses with foot pain subjected to MRI examination and medical therapy (2005-2007) were evaluated retrospectively. Data collected included history, signalment, occupation, duration and severity of lameness at the time of MRI, radiological and MRI abnormalities. Number of treatments, complications and long-term response to treatment were obtained by detailed telephone questionnaires. Association between clinical and MRI findings and long-term lameness were investigated.

RESULTS

Frequent abnormal structures included the navicular bone, the deep digital flexor tendon, the navicular bursa and the distal interphalangeal joint. Thirty-four of 56 horses (60.7%) failed to return to previous level of exercise due to persistent or recurrent lameness or owners' decision to decrease the horse's athletic level; however, 11 horses (32.3%) were being used for light riding. Prognosis for horses with concurrent deep digital flexor tendon, navicular bone and navicular bursa lesions was worse than horses with individual lesions. Deep digital flexor tendinopathy was strongly associated with persistent or recurrent lameness.

CONCLUSIONS

Horses with multiple foot lesions managed with conservative therapy have a guarded prognosis for long-term soundness. Deep digital flexor tendinopathies negatively influence prognosis.

Pharmacological effects of tiludronate in horses after long-term immobilization

INTRODUCTION

Tiludronate, a bisphosphonate, has recently been introduced in veterinary medicine to treat orthopedic conditions in the horse. This study was designed to evaluate its effects on biochemical biomarkers of bone metabolism and on bone density and structure in an experimental model of disuse osteoporosis induced by cast application in horses.

METHODS

Two groups of eight horses were immobilized during 8 weeks. The first group (P-group) received a placebo, and the second group (T-group) received tiludronate 1 mg/kg by slow IV infusion. Both treatments were administered twice, 28 days apart. Immobilization consisted of stall rest with the left forelimb packed in a fiberglass cast. It was followed by a 4-week remobilization period and an 8-week standardized training protocol. One biomarker of bone resorption, the C-telopeptides of type I collagen cross-links (CTX-1) and one biomarker of bone formation, the bone isoenzyme of alkaline phosphatase (bone ALP), were assessed. Metacarpus III (MCIII) bone mineral density (BMD) and speed of sound (SOS) were evaluated respectively by dual energy X-ray absorptiometry (DEXA) and quantitative ultrasonography (QUS). Lameness was regularly assessed during the remobilization and training periods. Group- and time-related effects were tested by analysis of variance on repeated measurements.

RESULTS

A rapid, transient and significant decrease in CTX-1 concentration was seen after each treatment in the T-group only. No significant differences between groups were seen in the evolution of bone ALP activity. At the end of the experiment, the loss of MCIII BMD measured by DEXA in the immobilized limb was significantly less in the T-group than in the P-group. The MCIII SOS measured by QUS did not significantly vary within or between groups throughout the study.

DISCUSSION AND CONCLUSIONS

Tiludronate was found to significantly reduce bone resorption during immobilization, as well as to prevent long-term osteopenia in the immobilized limb. Disuse osteopenia did not affect the lateral superficial cortex of MCIII.