Administration Of Botulinum Toxin Type Research Articles

Prevention of component separation in complex abdominal wall surgery by Botox prehabilitation: a propensity-matched study.

To facilitate midline fascial closure in complex abdominal wall surgery, component separation techniques (CST) are usually required. However, CST is associated with an enlarged morbidity. Prehabilitation could increase the compliance of the abdominal wall and thereby decrease the necessity of myofascial release. This can be accomplished by administration of botulinum toxin type A (BTA) in the lateral abdominal wall musculature. The aim of this study was to determine the effect of BTA on the subsequent necessity to perform CST in patients with complex abdominal wall hernias. Patients with a complex abdominal wall hernia, planned to undergo CST between July 2020 and November 2022 were included. Outcome of procedures with 300U of BTA 4 (2-6) weeks prior to surgery, were retrospectively analyzed by comparison with propensity matched subjects of an historical group. Hernia width difference was assessed by CT and operative details were included. A total of 13 patients with a median hernia width of 12cm (IQR 9-14, range 24) were prehabilitated with BTA between July 2020 and November 2022. A CST was planned for all, however not required in 6/13 patients (46%) to accomplish midline fascial closure. A mean elongation of lateral abdominal wall musculature of 4.01cm was seen in patients not requiring CST. Compared to the propensity score matched control group, a 27% reduction (p = 0.08) in the need for CST was observed. There is a tendency for decrease of necessity for CST by preoperatively administered BTA in patients with complex abdominal wall defects. Although small, as this study used propensity matched comparison, further exploration of BTA should be encouraged.

OnabotulinumtoxinA improves oral aperture in patients with scleroderma: A small clinical trial

Reduced oral aperture (ROA), resulting from systemic sclerosis (SSc), is a debilitating condition with limited treatment options. Improvement in oral function has been reported with perioral administration of botulinum toxin type A. To prospectively evaluate the efficacy of onabotulinumtoxinA (onabotA) injection in improving oral opening and quality of life in SSc patients with ROA. Seventeen women with SSc and ROA were treated with 16 units of onabotA in 8 different sites around the cutaneous lips. Measurements of maximum mouth opening were taken before treatment, at 2weeks posttreatment, and at 3months posttreatment. Function and quality of life were also assessed via surveys. Interincisor and interlabial distances were significantly increased 2weeks after treatment with onabotA (P<.001) but not 3months after. Subjective improvement in quality of life was noted. This single-institution study enrolled 17 patients and did not have a placebo control group. OnabotA appears to have a strong short-term symptomatic benefit in patients with ROA due to SSc, with possible benefit to quality of life.

Intrathecal administration of botulinum toxin type a antagonizes neuropathic pain by countering increased vesicular nucleotide transporter expression in the spinal cord of chronic constriction injury of the sciatic nerve rats

Botulinum toxin type A (BoNT/A) induces direct analgesic effects in neuropathic pain by inhibiting the release of substance P, calcitonin gene-related peptide (CGRP) and glutamate. Vesicular nucleotide transporter (VNUT) was responsible for the storage and release of ATP in vivo, and one of the mechanisms underlying neuropathic pain is VNUT-dependent release of extracellular ATP from dorsal horn neurons. However, the analgesic effect of BoNT/A by affecting the expression of VNUT remained largely unknown. Thus, in this study, we aimed to elucidate the antinociceptive potency and analgesic mechanism of BoNT/A in chronic constriction injury of the sciatic nerve (CCI) induced neuropathic pain. Our results showed that a single intrathecal injection of 0.1 U BoNT/A seven days after CCI surgery produced significant analgesic activity and decreased the expression of VNUT in the spinal cord of CCI rats. Similarly, BoNT/A inhibited the CCI-induced increase in ATP content in the rat spinal cord. Overexpression of VNUT in the spinal cord of CCI-induced rats markedly reversed the antinociceptive effect of BoNT/A. Furthermore, 33 U/mL BoNT/A dramatically reduced the expression of VNUT in pheochromocytoma (PC12) cells but overexpressing SNAP-25 increased VNUT expression in PC12 cells. Our current study is the first to demonstrate that BoNT/A is involved in neuropathic pain by regulating the expression of VNUT in the spinal cord in rats.

Intravesical electromotive administration of botulinum toxin type A in improving the bladder and bowel functions: Evidence for novel mechanism of action

Objective: To examine the hypothesis that what is the concomitant mechanism of action botulinum toxin type A (BoNTA) administration by intravesical electromotive into the bladder resulting in bladder function improvement. We also tried to confirm the possibility of retrograde trans-axonal transportation of toxin. Design: Animal study. Setting: Ten male rabbits were divided into two groups. Participants: Group 1 (G1) (n = 5) (BoNTA/EMDA), and group 2 (G2) (n = 5) the control group. Interventions: Animals in G1received 10 IU/Kg of intravesical BoNTA through a specific catheter for electromotive drug administration (BoNTA/EMDA). About 0.1–0.15 ml of toxin was diluted in 1 ml of distilled water. The maximum frequency of the device for drug solution delivery was set at 4 mA for 15 min. In G2 as the control group, the same procedure was performed to deliver normal saline to the bladder. Outcome measures: Multiple biopsies were taken from bladder’s contiguous structures one month postoperatively. The immunohistochemical (IHC) evaluation was performed with anti-clostridium botulinum toxoid type A mouse IgM monoclonal antibody. Results: In specimens of G1, BoNTA penetrated through muscular layers of the bladder wall and the staining was uniform in the urothelium, interstitium, and muscular layers. Positive IHC staining showed that BoNTA was traced in the upper and lower spinal cord in addition to pelvic nerve, sacral nerve plexus, intestine wall, and pelvic floor muscle. In G2, all the specimens were intact in IHC staining. Conclusions: The presence of BoNTA in lower and upper spinal cord suggests the possibility of retrograde trans-axonal transfer of toxin to lower and upper neural pathways which may result in simultaneous improvement in bladder and bowel functions.

Laryngeal Dystonia, New Approaches for Direct Botulinum Toxin Administration

To describe our experience in the treatment of laryngeal dystonia (in abduction and adduction), with special emphasis given to the technical aspects (approach procedure, dosage and type of botulinum toxin type A used), as well as treatment response and possible side effects. We conducted a cross-sectional descriptive study of a sample of patients with laryngeal dystonia treated by means of transoral administration of onabotulinumtoxinA or incobotulinumtoxinA over a period of 10 years (2007-2017). Data collected include demographic and clinical variables, treatment response (based on a self-rating scale), the duration of treatment and the appearance of side effects. Sample size: 15 patients (11 women; mean age: 44.06 years) with laryngeal dystonia (mean time since onset of 40 months; 12 patients with dystonia in adduction) and 174 administrations (92% incobotulinumtoxinA; average dosage of 5 U in each vocal cord). The procedure took an average of 11.7 minutes to perform. Response was good in 31% of the procedures and very good in 57.5%. Side effects were recorded in 14.4% of the procedures, although always mild and transitory, with a predominance of dysphagia and dysphonia. In our experience, transoral administration of botulinum toxin type A to treat laryngeal dystonia has proved to be a simple, quick, effective and safe technique.

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

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

Effect of botulinum toxin in disabling ectatocormia

Ectatocormia (severe, fixed truncal hyperextension exacerbated by movements of the trunk) is associated with pain and motor disability, and impide the patient to maintain a normal upright posture or to walk. The aim of this report is to present the case of an adult with ectatocormia and the changes in pain and posture after botulinum toxin administration to paraspinal muscles. A 28-year-old patient with congenital ataxia and trunk dystonia in hyperextension predominantly lumbar and left inclination. Presents pain, difficulty in sitting and walks with assistance from a person less than 10 meters indoors. Prior informed consent is treated with botulinum toxin type A, that was obtained in 100 u vials as Botox (Allergan Pharmaceuticals) and reconstituted with 2 mL of normal saline. The patient was placed prone with a cushion under the pelvis. Muscles were injected with ultrasound guidance and convex probe in three sites on each side, using a spinal needle and administrating 60 u at each site: 20 u multifidus, 20 u longissimus and 20 u iliocostalis at the level of the eleventh thoracic vertebrae, second and fourth lumbar vertebraes. Left quadratus lumborum muscle also received 40 u. The score reported by the parents in the Global Dystonia Severity Rankin Scale went down from 10 (pre-injection) to 5 (post-injection). Pain reduction was recorded indirectly by reporting of the parents who perceived the patient more relaxed and more smiling. An upright sitting without dorsal support/with support on hands was achieved of more than 10 seconds and a decrease in left inclination. No adverse effects were reported. The administration of botulinum toxin type A in the paraspinal muscles seems to be an effective treatment to reduce truncal hyperextension, besides the pain and disability that it produces.

Distonía laríngea: nuevas formas de administración terapéutica de toxina botulínica por vía directa

To describe our experience in the treatment of laryngeal dystonia (in abduction and adduction), with special emphasis given to the technical aspects (approach procedure, dosage and type of botulinum toxin type A used), as well as treatment response and possible side effects. We conducted a cross-sectional descriptive study of a sample of patients with laryngeal dystonia treated by means of transoral administration of onabotulinumtoxinA or incobotulinumtoxinA over a period of 10 years (2007-2017). Data collected include demographic and clinical variables, treatment response (based on a self-rating scale), the duration of treatment and the appearance of side effects. 15 patients (11 women; mean age: 44.06 years) with laryngeal dystonia (mean time since onset of 40 months; 12 patients with dystonia in adduction) and 174 administrations (92% incobotulinumtoxinA; average dosage of 5 U in each vocal cord). The procedure took an average of 11.7 minutes to perform. Response was good in 31% of the procedures and very good in 57.5%. Side effects were recorded in 14.4% of the procedures, although always mild and transitory, with a predominance of dysphagia and dysphonia. In our experience, transoral administration of botulinum toxin type A to treat laryngeal dystonia has proved to be a simple, quick, effective and safe technique.

The Effect of Intragastric Administration of Botulinum Toxin Type A on Reducing Adiposity in a Rat Model of Obesity Using Micro-CT and Histological Examinations.

Background/AimsBotulinum toxin type A (BTX), a long-acting inhibitor of muscular contraction in both striated and smooth muscles, is responsible for gastric motility. The aim of this study was to investigate the effects of an endoscopic intragastric BTX injection on weight loss, body fat accumulation, and gastric emptying time.MethodsThe BTX group consisted of 15 obese rats in which 20 U of BTX were injected into the gastric antrum. The saline group consisted of 15 obese rats injected with 20 U of saline, and the control group included 10 obese rats that did not receive a surgical intervention. The gastric emptying time, biochemical parameters, and body fat volume were evaluated using micro-computed tomography (micro-CT) and histologic evaluations.ResultsThe postoperative body weight of the BTX group was significantly lower than those of the other groups (p<0.001) at 6 weeks after the operation. The gastric emptying time (156±54 minutes) was significantly delayed in the BTX group. The BTX group showed significantly lower lipid levels than the other groups. A reduction in body fat volume was observed in the BTX group using micro-CT and histological evaluations.ConclusionsBTX application to the gastric antrum represents a potentially effective treatment for obesity and may help improve the lipid profile by increasing the gastric emptying time.

Keratoconus progression is not inhibited by reducing eyelid muscular force with botulinum toxin A treatment: a randomized trial.

To evaluate whether reducing eyelid muscular force through the administration of botulinum toxin type A (BTX-A) to the orbicularis oculi muscles of patients with keratoconus affected corneal parameters indicative of disease progression. In this prospective parallel randomized clinical trial, 40 eyes of 40 patients with keratoconus were randomized into equally sized control and BTX-A groups. Patients in the BTX-A group received subcutaneous BTX-A injections into the orbicularis muscle. The control group received no intervention. Palpebral fissure height, best spectacle-corrected visual acuity (BSCVA), and corneal topographic parameters were evaluated at baseline and at 3-, 6-, 12-, and 18-month follow-ups. The mean ± standard deviation vertical palpebral fissure heights were 9.74 ± 1.87 mm and 9.45 ± 1.47 mm at baseline in the control and BTX-A groups, respectively, and 10.0 ± 1.49 mm and 9.62 ± 1.73 mm at 18 months, with no significant difference between the groups (p=0.337). BSCVA values were 0.63 ± 0.56 and 0.60 ± 0.27 at baseline in the control and BTX-A groups (p=0.643), and 0.52 ± 0.59 and 0.45 ± 0.26 at 18 months, again with no significant difference between the groups (p=0.452). In addition, there were no statistical differences between the groups at 18 months for the three keratometry topographic parameters: flattest (K1), steepest (K2), and mean (Km) keratometry (p=0.562). BTX-A inhibition of eyelid force generation did not result in detectable changes in corneal parameters in keratoconic patients during 18 months of follow-up.

Repeated injections of botulinum toxin into the masseter muscle induce bony changes in human adults: A longitudinal study.

ObjectiveTo evaluate soft- and hard-tissue changes in the mandibular angle area after the administration of botulinum toxin type A (BoNT-A) injection to patients with masseteric hypertrophy by using three-dimensional cone-beam computed tomography (3D-CBCT).MethodsTwenty volunteers were randomly divided into two groups of 10 patients. Patients in group I received a single BoNT-A injection in both masseter muscles, while those in group II received two BoNT-A injections in each masseter muscle, with the second injection being administered 4 months after the first one. In both groups, 3D-CBCT was performed before the first injection and 6 months after the first injection.ResultsMasseter muscle thicknesses and cross-sectional areas were significantly reduced in both groups, but the reductions were significantly more substantial in group II than in group I. The intergonial width of the mandibular angle area did not change significantly in either group. However, the bone volume of the mandibular gonial angle area was more significantly reduced in group II than in group I.ConclusionsThe repeated administration of BoNT-A injections may induce bone volume changes in the mandibular angle area.

Intra-articular injection of Botulinum toxin A reduces neurogenic inflammation in CFA-induced arthritic rat model

Currently, administration of Botulinum toxin Type A (BoNT/A) to treat arthritic pain has promising efficacy in clinical research. However, the mechanisms underlying anti-neurogenic inflammation mediated by BoNT/A remains unclear. The aim of this study was to demonstrate the effectiveness in macro and micro levels and to explore the causal mechanism of BoNT/A.Wistar rats (n = 60) were injected with 50ul complete Freund's adjuvant (CFA) in the left ankle joint capsule to establish a model of chronic monoarthritis. Pain behaviour (Evoked pain assessment) and infrared thermal imaging testing were performed at the macroscopic level to assess the effectiveness of analgesia and anti-inflammation. Western blotting and immunofluorescence staining were used at the microscopic level in an attempt to determine the mechanisms of anti-nociceptive or anti-inflammatory effects of BoNT/A. Additionally, hematoxylin-eosin staining was also used to visualise the cartilage and the synovial degenerative conditions of arthritis. By comparing the outcome of the evoked pain test and immunofluorescence staining, there was a significant improvement in BoNT/A compared with the normal saline (NS) injected control group. In addition, thermal variations showed that the temperature of ipsilateral ankle joint increased between 1 and 2 weeks following injection of CFA, but decreased after 3 weeks (still above the contralateral side). However, the temperature showed no difference between the BoNT/A group and NS group after treatment. The expression of IL-1β or TNF-α in the ankle synovial tissue was significantly decreased in the BoNT/A group compared to the NS group (p < 0.05). Based on the HE assessment, cartilage degeneration and infiltration of inflammatory cells in the BoNT/A group was alleviated compared to the NS group after treatment. In conclusion, we proposed the hypothesis that intra-articular BoNT/A administration does play an important role in anti-neurogenic inflammation. The possible mechanisms might be that BoNT/A prevents the release of nociceptive nerve peptides at the injection site and then suppresses the expression of inflammatory cytokines.

Questions of pathogenesis and treatment of post-stroke spasticity

Post-stroke spasticity considerably limits the ability to move for patients, hinders nursing, and contributes to the formation of pain syndromes. The article tells about the current understanding of the pathogenesis of cerebral spasticity, and discusses baseline treatment and rehabilitation activities. Administration of botulinum toxin type A for managing increased muscle tone in patients with stroke is considered in detail.

Botulinum neurotoxin type A in the treatment of classical Trigeminal Neuralgia (BoTN): study protocol for a randomized controlled trial.

BackgroundTrigeminal neuralgia is characterized by paroxysmal facial pain attacks. Adequate prophylactic drug therapy is often limited by the lack of efficacy and intolerance due to central nervous system side effects.Subcutaneous injections of botulinum toxin type A are a promising treatment option for patients with unsatisfactory response to drug therapy or neurosurgical intervention. Its effects are expected to last for at least 3 months, so it could be a potential long-term treatment.This is the study protocol of a prospective, placebo-controlled, double blind clinical trial investigating the add-on therapy of subcutaneous administration of botulinum toxin type A injections to standard treatment in therapy-refractory classical trigeminal neuralgia.Methods and designBoTN is a prospective, double blind, placebo-controlled trial with a randomized withdrawal design in which a single blind phase is followed by a double blind phase (see also Methods and design). Eligible patients with classical trigeminal neuralgia who are otherwise refractory to medical and neurosurgical treatment will receive subcutaneous injections of botulinum toxin type A into injection sites of the affected trigeminal branch.In the first phase all patients will receive botulinum toxin type A in a single blinded intervention. Twelve weeks later therapy responders will be allocated to the verum or placebo (saline) arm in a double blind, randomized manner. These injections will be performed at the same sites as the first injections.This trial will be conducted in a tertiary outpatient clinic specialized in the treatment of headache and facial pain. There will be three investigators performing the injections who are experienced in the treatment of headache and facial pain and trained in botulinum toxin type A injections.DiscussionBoTN is designed to assess the efficacy and safety of subcutaneous botulinum toxin type A injections in addition to standard prophylactic treatment in therapy-refractory trigeminal neuralgia.Trial registration numberEU Clinical Trials Register: EudraCT-No: 2014-001959-24 https://www.clinicaltrialsregister.eu/ctr-search/rest/download/trial/2014-001959-24/DEDate of trial registration26 August 2014Electronic supplementary materialThe online version of this article (doi:10.1186/s13063-015-1052-z) contains supplementary material, which is available to authorized users.

Prevention of unfavourable effects of cigarette smoke on flap viability using botulinum toxin in random pattern flaps: An experimental study

Background There are numerous clinical and experimental studies reporting unfavourable effects of cigarette smoke on skin flaps. Objective To investigate whether unfavourable effects of cigarette smoke on flap survival could be reduced by botulinum toxin type A. Methods Twenty-eight male Wistar albino rats (15 months of age, mean weight 210 g [range 180 g to 230 g]) were included. They were divided into four groups of seven animals each. The control group underwent the surgical procedure alone. Surgical procedure was performed after administration of botulinum toxin type A in the botulinum toxin (BTX) group, after exposure to cigarette smoke in the cigarette smoke (CS) group, and after BTX type A administration and exposure to CS in the CS+BTX (CS+BTX) group. Random pattern cutaneous flaps (3 cm × 9 cm) were elevated from the dorsum of all rats. Necrosis area was calculated in percentages (%) using Image J computer software. Tissue samples were examined histopathologically. Results The mean necrotic area in the control group (26%) and in the BTX group (21%) were similar (P=0.497), whereas administration of BTX type A significantly decreased flap necrosis area in the rats exposed to CS (the mean necrosis areas were 41.5% in the CS group, and 26% in the CS+BTX group; P&lt;0.001). Histopathological examination findings corroborated the unfavourable effects of CS and preventive effects of BTX type A. Conclusion Preoperative administration of BTX significantly enhanced flap viability in the rats exposed to CS. Further human studies are warranted to verify whether BTX type A could be used as an agent to reduce the risk of flap necrosis in patients who smoke.

Safe Administration of Botulinum Toxin Type A Injections During Pregnancy: A Report of Two Cases

Local injections of botulinum toxin type A (BoNT/A) are safe and efficacious to treat focal and segmental dystonia. However, there are no adequate studies in humans regarding the safety of BoNT/A during pregnancy. Despite the fact that 25 case reports have been published on patients who received BoNT/A injections during a total of 31 pregnancies, in only 3 patients were the injections continued beyond the first trimester. We report on 2 females with cervical and segmental dystonia who received BoNT/A injections during pregnancy beyond the first trimester and gave birth to 2 healthy children.

Integrated Rehabilitation Treatment of Focal Spasticity after Botulinum Toxin Type-A Injection

Several treatments have been proposed for the management of spasticity. The injection of botulinum toxin type A is considered the gold standard treatment and appears to be safe and effective. The combination between botulinum toxin type A (BTX-A) and physiotherapy (FKT) is thought to be able to enhance the effects. The aim of this study was to assess the effectiveness of the administration of botulinum toxin type A when combined with a specific rehabilitation protocol in subjects with focal spasticity. 44 subjects were randomly divided into two groups (A and B). All subjects underwent ECO and EMG guided BTX-A injection. After the injection group A underwent a complex rehabilitation protocol with functional electrical stimulation, functional bandaging, manual therapy, cognitive sensory motor training and focal vibration on the treated muscle; group B made functional rehabilitation at home. Both groups improved spasticity, pain and function in the first month after the inoculation (T1) but only in group A an improvement at the follow up performed in the subsequent 9 months was observed. According to the results, it may be suggested that the inoculation of Botulinum toxin A should be properly placed within a specific rehabilitation program.

Prevention of unfavourable effects of cigarette smoke on flap viability using botulinum toxin in random pattern flaps: An experimental study.

There are numerous clinical and experimental studies reporting unfavourable effects of cigarette smoke on skin flaps. To investigate whether unfavourable effects of cigarette smoke on flap survival could be reduced by botulinum toxin type A. Twenty-eight male Wistar albino rats (15 months of age, mean weight 210 g [range 180 g to 230 g]) were included. They were divided into four groups of seven animals each. The control group underwent the surgical procedure alone. Surgical procedure was performed after administration of botulinum toxin type A in the botulinum toxin (BTX) group, after exposure to cigarette smoke in the cigarette smoke (CS) group, and after BTX type A administration and exposure to CS in the CS+BTX (CS+BTX) group. Random pattern cutaneous flaps (3 cm × 9 cm) were elevated from the dorsum of all rats. Necrosis area was calculated in percentages (%) using Image J computer software. Tissue samples were examined histopathologically. The mean necrotic area in the control group (26%) and in the BTX group (21%) were similar (P=0.497), whereas administration of BTX type A significantly decreased flap necrosis area in the rats exposed to CS (the mean necrosis areas were 41.5% in the CS group, and 26% in the CS+BTX group; P<0.001). Histopathological examination findings corroborated the unfavourable effects of CS and preventive effects of BTX type A. Preoperative administration of BTX significantly enhanced flap viability in the rats exposed to CS. Further human studies are warranted to verify whether BTX type A could be used as an agent to reduce the risk of flap necrosis in patients who smoke.

Intrathecal administration of botulinum toxin type A improves urinary bladder function and reduces pain in rats with cystitis.

Botulinum toxin A (Onabot/A) has been shown to have an antinociceptive effect. This might be due to an impairment of sensory nerves not only in the peripheral but also in the central nervous system. In this work, we analysed both systems by studying the effect of intrathecal (i.t.) administration of botulinum toxin A in an animal model of bladder pain and hyperactivity induced by cyclophosphamide (CYP). Rats were implanted with an i.t. catheter at the L6 segment. Bladder pain was induced by intraperitoneal (i.p.) injection of CYP. Five experimental groups were created: (1) Saline i.p. + i.t.; (2) Onabot/A i.t.; (3) CYP i.p. + saline i.t.; (4) CYP i.p. + Onabot/A i.t. 48 h after CYP; and (5) Onabot/A i.t. 30 days. Mechanical sensitivity was assessed in the abdomen and hindpaws. Motor activity was observed in an open-field arena. Bladder reflex activity was evaluated by cystometry. At the end, bladders and spinal cord were immunoreacted (IR) against cleaved SNAP-25 (cSNAP-25), c-Fos, p-ERK, calcitonin gene-related peptide (CGRP) and GAP43. The toxin reduced pain symptoms, bladder hyperactivity, expression of neuronal activation markers and CGRP, typically up-regulated in this inflammatory model. The presence of cSNAP-25 was detected in the spinal cord and bladder fibres from animals treated with Onabot/A. No somatic or visceral motor impairments were observed. Our findings suggest that i.t. Onabot/A has a strong analgesic effect in a model of severe bladder pain. This route of administration can be further explored to treat intractable forms of pain.

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

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). 10 Quarter Horses with degenerative injury to the PA. 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. 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. 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.