The effect of the tarsal joint positions on the tibial nerve motor action potential latency in dog: electrophysiological and anatomical studies

This study has been carried out to determine the effect of neutral position, hyperextension and hyperflexion of the tarsal joint on the tibial nerve, motor action potential latency and tarsal canal compartment pressure in dogs with the aid of electrophysiological and anatomical methods. Totally twenty healthy mongrel dogs were used. Latency of motor nerve action potential (MNAPL) studies of tibial nerve via surface stimulating and needle recording electrodes was performed on right hind limbs of all the dogs. The compartment pressures of the tarsal canal with the pressure transducer were determined from both limbs from ten of the dogs. In one dog, tarsal regions of both left and right limbs were demonstrated using magnetic resonance imaging (MRI). Two dogs were euthanatized and tarsal regions of the dogs were sectioned for correlative anatomy. Nerve conduction studies showed that the MNAP latency of the tibial nerve were 3.55 +/- 0.097 ms, 3.76 +/- 0.087 ms and 3.39 +/- 0.097 ms in neutral, hyperextension and hyperflexion positions, respectively. Hyperflexion of the tarsal joint caused prolongation of the MNAP latency of the tibial nerve with the highest pressure value being determined in tarsal canal. From the anatomical viewpoint, the distance between the flexor hallucis longus muscle and the superficial digital muscle was the shortest during hyperflexion and the plantar branch of saphenous artery, lateral and medial plantar nerves located more laterally in cadaver and MR imaging sections. As a result of this study, it is thought that tarsal region diseases as well as long time splint in the hyperflexion position as applied in the Ehmer sling can affect the compartment pressure and nerve tension because of occupying in the tarsal canal. Raising pressure and nerve stretching in the tarsal canal compartment could cause deficiencies in the conduction velocity of the tibial nerve. This might be a result of tarsal tunnel syndrome in the dog. Clinicians could consider this syndrome in cases of tarsal region diseases as well as application of long time splint in hyperflexion of tarsal joints in dogs.     

Feline talocrural luxation: a cadaveric study of repair using ligament prostheses

Currently recommended surgical techniques to treat severe biaxial feline talocrural soft-tissue injuries commonly lead to unsatisfactory outcome. Data relating to canine talocrural stabilisation may not be useful in cats due to major differences in tarsal anatomy between the species. This experimental biomechanical cadaveric study used specimens (n = 10) prepared from the distal pelvic limbs of five adult cats. The aim was to design a technique for treating talocrural luxation using suture prostheses and bone tunnels, and to investigate its suitability for use in clinical cases. Four prosthetic ligaments were placed through a series of five 1.5 mm bone tunnels. Two prostheses, the caudoproximal pair, were taut in talocrural flexion and two prostheses, the craniodistal pair, were taut in extension. The intact specimens had their range-of-motion (ROM) and stability tested, after which they were transected at the talocrural joint (simulated luxation) and repaired using the technique described. The ROM and stability of the repaired specimens were tested and compared to the intact specimens. The repaired specimens had comparable stability to the intact specimens, although the ROM was different (p <0.05) in six of 16 positions (p <0.003125). These corresponded to the positions where the lateral prostheses were taut. The repair technique described may be useful in the treatment of talocrural luxation, as it is low-profile in an area of limited soft-tissue cover, allows anatomic reduction, restores normal talocrural joint stability and near-normal tarsal ROM.     

Intraaticular treatment of tarsal degenerative joint disease in cattle.

Tarsal degenerative joint disease (DJD) in 12 cattle was classified as primary or secondary, based on age, evidence of hereditary or congenital joint conformation defects, faulty hindlimb alignment, duration and type of usage joints were subjected to, and history or signs of repeated trauma. Three of the cattle had bilateral primary tarsal DJD, 7 had bilateral secondary tarsal DJD, and 2 had secondary DJD of the left tarsus. Analyses of synovial fluid samples provided a means of characterizing pathologic changes of tarsal DJD, Results of blood and synovial fluid analyses were grouped in compilation of data for cattle affected with either primary or secondary tarsal DJD. Corticosteroids and a long-acting synthetic progestational agent were injected singly or in combination with aqueous antibiotics into affected tarsal joints. Tarsal joints of 5 of the cattle responded favorably to a single intraarticular treatment, as manifested by palliative relief and functionally usable joints. Seven joints of 5 cattle were subjected to repeated intraarticular treatment. Serial synovial fluid analyses in 7 of the cattle provided a means of assessing tarsal joint response to intraarticular treatment or to therapeutic arthrocentesis, exclusive of patient objective response. One cow developed a mild self-limiting bilateral postinjection synovitis that was resolved after the 2nd and final intraarticular injection. Usable function returned to tarsal joints of cattle that responded favorably to intraarticular treatment at different periods after single or repeated injections. Three cattle with advanced tarsal DJD experienced minor temporary relief and were euthanatized at their owner's request. Improvement did not occur in the tarsal joint of 1 cow subjected to therapeutic aspiration only. Intraarticular treatment in all cattle was considered supportive to the animal's well-being rather than curative.     

Third tarsal bone osteonecrosis associated with chronic recurrent cellulitis in an adult horse

A 17-year-old Irish Draught cross gelding with a history of chronic recurrent right hindlimb cellulitis was evaluated due to acute onset of severe lameness affecting this limb. Scintigraphic examination identified marked radiopharmaceutical uptake within the central and third tarsal bones and the lameness improved following tibial and peroneal nerve blocks. Distal intertarsal joint collapse was observed but the radiographic changes were considered insufficient to explain the lameness severity. Magnetic resonance imaging revealed marked bone pathology affecting both the central and third tarsal bones. A subcutaneous abscess developed on the dorsolateral aspect of the limb, but clear evidence of joint infection was not established. Computed tomography showed lytic lesions affecting mainly the third tarsal bone, so the animal was treated surgically for suspected osteomyelitis involving this bone by implantation of gentamicin impregnated polymethylmethacrylate. Shortly following surgery the horse developed gastric rupture and was euthanased. Osteonecrosis of the third tarsal bone was identified, but sepsis was not demonstrated to be the cause. It is hypothesised that osteonecrosis developed as a sequel to chronic osteomyelitis which may have responded to previous antimicrobial treatment. The report also highlights the importance of gastric disorders as a differential for discomfort in animals undergoing treatment for orthopaedic disease.     

Congenital tarsal hyperextension in three cats

CASE DESCRIPTION: 3 kittens were examined because of a malformation affecting the hind limbs, resulting in an inability to bear weight or ambulate normally. CLINICAL FINDINGS: 2 kittens were younger than 6 weeks of age, and 1 was 4 months of age at the time of initial examination. The congenital abnormality was characterized by severe tarsal hyperextension in which weight was borne on the cranial aspect of the tarsus, and the plantar surface of the metatarsus faced dorsally. In 2 kittens, the condition affected both hind limbs, and in the older kitten, the condition was unilateral. In the 2 kittens in which radiographs were obtained, no bone abnormalities were detected. Full-cylinder fiberglass casts were applied and changed weekly to accommodate growth. Owners administered physical therapy after final cast removal. TREATMENT AND OUTCOME: Conservative management involving external coaptation and physical therapy led to favorable results in all 3 cats. CLINICAL RELEVANCE: Although further studies are needed to determine the etiology of the disorder, affected kittens may be successfully treated with conservative management. Owners should be committed to the necessity for returning cats for serial cast changes, care for pressure sores, and administration of physical therapy after cast removal.     

Effect of standing tarsal angle on joint kinematics and kinetics

REASONS FOR PERFORMING STUDY: The tarsal joint is a frequent site of lameness, but little objective information is available regarding the effects of tarsal conformation on joint movements or forces. OBJECTIVE: To compare tarsal kinematics and kinetics in horses with large, intermediate and small tarsal angles. METHODS: Sagittal plane standing angle of the right tarsal joint was measured in 16 horses as they stood squarely with the hind hooves vertically beneath the hip joint. Tarsal angles were classified as small (< 155.5 degrees), intermediate (155.5-165.5 degrees) or large (> 165.5 degrees). Reflective markers, attached over the centres of joint rotation, were tracked during stance as the horses trotted across a force plate at a standardised speed. Joint angles and ground reaction forces were combined with morphometric data to calculate net joint moments and net joint powers across the tarsus using inverse dynamics. RESULTS: In all horses, the tarsus flexed during the impact phase and extended in late stance. Tarsal angles were stratified according to standing tarsal angle throughout stance. Horses with large standing angles showed less flexion and less energy absorption at the tarsus during the impact phase than those with intermediate or small angles and generated less vertical impulse than horses with small standing angles. Net extensor moment at the tarsus during stance was lower for horses with large standing angles. CONCLUSIONS: In horses with large tarsal angles, less concussion was absorbed during the impact phase, which may be a factor in the development of degenerative joint disease; and the smaller vertical impulse and extensor moment later in stance may limit propulsive ability. However, the smaller net joint moment may reduce the risk of plantar ligament desmitis. CLINICAL SIGNIFICANCE: The effects of conformation on kinematics and kinetics of the tarsal joint may influence both performance and soundness.     

Use of ethanol in the treatment of distal tarsal joint osteoarthritis: 24 cases

Reasons for performing this study: Intra‐articular ethanol has been described to promote distal tarsal joint ankylosis. Its use and results in clinical cases affected by osteoarthritis (OA) have not been reported. Objectives: To describe and evaluate the results of treatment of distal tarsal joint OA by facilitated ankylosis stimulated by intra‐articular ethanol injection. Methods: Twenty‐four horses met the inclusion criteria of tarsometatarsal and centrodistal joint OA diagnosed by a positive response to intra‐articular analgesia, radiographic evaluation and recurrence of lameness ≤4 months after intra‐articular medication with a corticosteroid. Horses were sedated and, following a radiographic contrast study of the tarsometatarsal joint, medication with 2–4 ml of either 100% pure ethanol (G100) or a 70% ethanol (G70) solution was applied. Horses were classified as improved based on a 50% reduction from initial lameness grade combined with an increase in exercise level. Results: Of the 24 horses included in this study, 20 had the treatment performed bilaterally and 4 unilaterally. All horses were available for initial follow‐up examination and 21 for a second one 6–9 months after treatment. This represented a total of 44 treated limbs and 35 available for long‐term follow‐up. Of these, 21/35 (60%) were considered improved, which corresponds to 11/21 horses (52%). Of 21 horses, 4 (19%) deteriorated and 2 of these developed significant complications related to treatment. Conclusions: Distal tarsal joint ankylosis with ethanol should be considered a safe and economic treatment in cases of distal tarsal joint OA that fail to show long‐term improvement with intra‐articular corticosteroid treatment. Potential relevance: Ethanol should be considered in the treatment of certain cases of distal tarsal joint OA. The importance of performing an adequate radiographic contrast study of the tarsometatarsal joint prior to treatment is highlighted.     

Third tarsal bone fractures in the greyhound

Objective : To describe the signalment, morphology, response to treatment and prognosis of third tarsal bone fractures in the racing greyhound. Methods : All third tarsal bone fractures seen by the author over a ten year period were included in the study. Diagnosis was by radiography. Treatments were reconstruction with a lag screw, fragment removal, centrodistal joint arthrodesis or conservative management. Results : Twenty-three cases were included in the study of which 16 cases were recent and seven cases chronic fractures. The chronic cases had been rested from between three and six months before an examination for recurrent lameness. There were five concomitant second tarsal bone fractures. Partial dorsal collapse was present in four cases. Thirteen dogs had lag screw fixation; three were lost to follow-up, seven returned to racing and three, all with partial tarsal collapse, failed to return to racing. Two dogs that had a centrodistal joint arthrodesis and one dog treated by rest alone raced again. Two dogs that had fragment removal failed to return to racing. Clinical significance : Veterinary examination of greyhounds with third tarsal bone fractures is often not sought at the time of the initial injury due to the benign presenting signs. Recurrence of lameness after rest is common. The prognosis for a successful return to racing would appear to be good following fragment fixation in both acute and chronic cases without dorsal tarsal collapse. Centrodistal joint arthrodesis may encourage bone union. The prognosis for conconservatively treated cases is guarded. Fragment removal is not recommended as a treatment.     

Osteochondritis dissecans of the tibial tarsal bone in dogs

The clinical histories of nineteen cases of osteochondritis dissecans of the medial ridge of the tibial tarsal bone are described. The clinical signs were lameness and a reduced range of joint flexion. Radiography demonstrated changes over the medial ridge of the tibial tarsal bone. Untreated cases remained lame and the rapid development of degenerative joint changes was noted. Cases treated promptly by arthrotomy, removal of the detached flap of cartilage and curettage made a quick and permanent recovery. Access to the lesion was gained by a postero-medial approach.     

Polyarthritis in a young cat

A 3-year-old cat had polyarthritis involving both tarsal joints and the right carpal joint. The condition was associated with pyrexia and regional lymphadenopathy. The aetiology of the arthritis was not determined, but no bacterial or mycoplasmal agent could be isolated from the synovial fluid obtained from one of the affected joints. Prednisolone, administered on a reducing dosage schedule, induced lasting remission of the clinical signs.     

Septic tenosynovitis of the tarsal sheath of an Arab gelding and suspected sepsis of the lateral digital flexor tendon subsequent to bacterial peritonitis

A 21-year-old Arab gelding with clinical signs of acute peritonitis had a perforating ulcer on the mesenteric border of the jejunum which resulted in localised contamination of the abdomen with ingesta. The affected segment of jejunum was resected and the abdomen was lavaged extensively. Postoperatively, the gelding was treated with broad-spectrum antibiotics, non-steroidal anti-inflammatory drugs and intravenous fluids, but after four days it became acutely non-weight bearing on its right hindlimb, and a tendonitis of the lateral digital flexor tendon within the tarsal sheath was identified ultrasonographically. The septic tendonitis was treated with broad-spectrum antibiotics but progressed proximodistally within the tendon until it involved both the tarsal sheath and the associated tarsocrural joint, necessitating the euthanasia of the gelding.     

Cytologic analysis of synovial fluid in clinically normal tarsal joints of young camels (Camelus dromedarius)

BACKGROUND: Camels are important in the racing industry and for milk, meat, and hair production in the Middle East. Evaluation of synovial fluid is an important part of the assessment of musculoskeletal injuries in this species. Information in the literature regarding synovial fluid in camels is limited. OBJECTIVES: The objective of this study was to determine the protein and cellular composition of synovial fluid from the tarsal joints of clinically normal, young camels (Camelus dromedarius). METHODS: Thirty clinically healthy, male camels, aged 9 to 12 months, were used in the study. Synovial fluid samples were collected from the right and left tarsal joints. Samples were processed within 60 minutes after collection. Total nucleated cell counts (TNCC) were assessed using a hemacytometer. Total protein concentration was determined using a refractometer. RESULTS: Forty-six samples were analyzed. The TNCC (mean +/- SD) was 175.8 +/- 136.7 cells/microL (range 50-678 cells/microL). Differential cell percentages were obtained for lymphocytes (58.2 +/- 21.55%, range 15-90%), monocyte/macrophages (38.3 +/- 20.8%, range 10-85%), and neutrophils (3.5 +/- 5.1%, range 0-15%). Protein concentration was 2.1 +/- 0.6 g/dL (range 1-3 g/dL). Significant differences were not observed in any parameters between right and left tarsal joints. CONCLUSION: Synovial fluid reference values were established and may be useful in the clinical investigation of joint disease in young camels.     

Surgical treatment of tarsal sheath effusion associated with an exostosis on the calcaneus of a horse

A 2-year-old Thoroughbred colt was referred for evaluation of effusion within the tarsal sheath and associated lameness of the right hind limb. Conservative treatment consisting of needle aspiration and pressure bandaging had been unsuccessful. Radiography of the right tarsus revealed proliferative periosteal reaction along the distal caudal border of the sustentaculum tali and medial aspect of the calcaneus. The owners elected conservative treatment, using a local injection of corticosteroid and pressure bandaging the tarsus. Five months later, the severity of the effusion and lameness had increased. Radiography revealed increased reactive bone along the sustentaculum tali and mineralization of the plantar tarsal ligament and tarsal sheath. Surgical exploration revealed fibrous adhesions between the medial aspect of the calcaneus and the flexor tendon and associated soft tissue mineralization. The adhesions were broken down and the reactive bone along the calcaneus was removed. The mineralized soft tissue within the tarsal sheath was excised. Five months after surgery, the horse was sound at the trot, with only minimal tarsal sheath effusion. The response to treatment for tarsal sheath effusion and lameness caused by bony changes of the sustentaculum tali is often unsatisfactory. After responding poorly to conservative treatment, the horse in this report had a favorable outcome to the surgical intervention of this condition.     

Alteration of distal tarsal subchondral bone thickness pattern in horses with tarsal pain

REASONS FOR PERFORMING STUDY: Understanding of the development of pathology and source of pain in distal tarsal osteoarthritis is poorly understood. Magnetic resonance imaging is often used in the analysis of human osteoarthritis (OA) because it is sensitive to early changes. HYPOTHESIS: In association with distal tarsal joint (DTJ) pain, there will be an alteration in the characteristic subchondral bone (SCB) thickness pattern of horses with no history of pain when subjected to low-level exercise. METHODS: Sixteen cadaver tarsal joints were collected from 9 mature horses with a history of tarsal pain and radiographic evidence of OA; 3 cadaver tarsi were collected from 2 mature horses with a history of tarsal pain and no radiographic abnormality. Magnetic resonance images were acquired using high-resolution sagittal 3D T1 weighted spoiled gradient echo sequence. Subchondral bone thickness was measured on sagittal images at dorsal and plantar locations on the proximal and distal aspects of the central (CT) and third (T3) tarsal bones and proximal aspect of the third metatarsal bone (MT3). RESULTS: In tarsi with radiographic evidence of OA medial and lateral SCB thicknesses were greater than midline on the proximal and distal aspects of CT and T3. Lateral SCB thickness was greater than medial on the proximal aspect of MT3. There was an increase in SCB thickness at the majority of sites compared with normal horses. There were too few joints in the group without radiographic changes to analyse statistically. In painful tarsi SCB thickness was greater medially than laterally at all sites. In horses without tarsal pain all lateral sites had greater SCB thickness, except the proximal aspect of CT. CONCLUSIONS: There is alteration of normal SCB thickness patterns in painful tarsi. Different thickness patterns could represent different types of pathological processes. Potential clinical relevance: Further work is required to elucidate the pathological processes leading to OA of the DTJs.     

Three-dimensional kinematic analysis of horses with induced tarsal synovitis

REASONS FOR PERFORMING STUDY: Techniques for 3D analysis have recently been developed. This study applied 3D kinematic analysis to describe the effects of lameness in the distal intertarsal (DIT) and tarsometatarsal (TMT) joints; complex joints such as this may show measurable amounts of movement outside the sagittal plane that may change in response to pathological conditions. HYPOTHESIS: Three-dimensional motions of the tarsal joint change after the induction of synovitis at the DIT and TMT joints. METHODS: Twelve retroreflective markers, attached on the skin over the right limb, were used to develop 3D coordinate systems for tibial and metatarsal segments. Data were collected at trot from 4 horses on 2 occasions, before (sound condition) and after (lame condition) induction of synovitis of the DIT and TMT joints. Ranges of 3D motions of the metatarsal segment relative to the tibial segment were compared between sound and lame conditions using t tests. RESULTS: There were significant decreases (P<0.05) in tarsal joint flexion and cranial translation of the metatarsus relative to the tibia during stance, and in proximal translation of the metatarsus during swing. CONCLUSIONS AND POTENTIAL RELEVANCE: In the lame condition, reduced cranial translation at the DIT and TMT joints may lead to a reduction in the motion of the articular cartilage surfaces relative to each other, which may have adverse effects on cartilage nutrition and function. Further studies of tarsal 3D kinematics in horses with bone spavin could allow quantification of the biomechanical effects of the special shoes used for conservative treatment.     

Micromorphology and topography of tarsal joint capsule's vascular elements in cats and dogs

Both cats and dogs belong to animals with the same type of limb support but have different nature of movement. Despite belonging to digitigrade animals, cats and dogs have a different nature of motion. While moving, the medial joint surface in cats and lateral surface in dogs carry the larger pressure. The aim of the study was to compare the similar surfaces of the cat's and dog's tarsal joint capsule and to detect differences in its histostructure and vascularisation. For the study, we used the capsule of the tarsal joint of five cats and five dogs dissected with accordance to anatomical surfaces. Sections of the capsule joint were stained with haematoxylin–eosin. The sections were examined with a microscope at magnification ×250 and ×400. The statistical analysis of the results was done using Student's t test. During the research, a difference in histostructure and vascularisation of tarsal joint capsule in cats and dogs on respective surfaces were found. The medial surface of the tarsal joint capsule was the most saturated with hemomicrocirculatory bed structures in cats, whereas this was the lateral surface in dogs. The most active metabolic processes also take place in these areas of the joint capsule, which is important to know when prescribing therapeutic procedures and determining an optimal surgical access.     

Complications following tarsal arthrodesis using bone plate fixation in dogs

OBJECTIVES: To report the complications encountered following tarsal arthrodesis surgery with bone plate fixation and describe the previously unreported complication of plantar necrosis. METHODS: Medical records of 40 dogs that had been treated by tarsal arthrodesis with bone plate fixation were reviewed to determine the major and minor complications and the associated risk factors. RESULTS: The major complication rate was 32.5 per cent and the minor complication rate was 42.5 per cent. Pantarsal arthrodeses had a higher major complication rate than partial tarsal arthrodeses. Plantar necrosis was the most common major complication and occurred in 15 per cent of cases. Plantar necrosis occurred more frequently when a bone plate was applied to the medial aspect of the hock, and only occurred in cases where tarsometatarsal joint arthrodesis was performed. CLINICAL SIGNIFICANCE: Plantar necrosis is a catastrophic complication that may be associated with injury to the dorsal pedal artery or perforating metatarsal artery. Application of a bone plate to the medial aspect of the hock should be performed with care during tarsal arthrodesis, particularly where the tarsometatarsal joint is debrided of cartilage. Strict attention to surgical technique and proper postoperative coaptation is critical to reduce the potential for complications with tarsal arthrodesis.     

Desmitis of the medial tarsal collateral ligament in 7 horses

Severe lameness, tarsocrural joint effusion and medially focused peritarsal swelling combined with focal pain on palpation are clinical signs suggestive of acute injury to the medial tarsal collateral ligament. Diagnosis can be made on physical examination and ultrasonographic findings; however, magnetic resonance imaging may provide more information especially with subtle injury. Acute exacerbation of the injury during the prolonged convalescence is common. The prognosis for medial tarsal collateral ligament desmitis appears good for survival but fair for return to previous levels of performance and requires prolonged periods of rest and a controlled exercise programme.     

Chemical arthrodesis of the distal tarsal joints using sodium monoiodoacetate in 104 horses

OBJECTIVE: To evaluate chemical arthrodesis using sodium monoiodoacetate for treatment of degenerative joint disease of the tarsometatarsal and distal intertarsal joints. DESIGN: Retrospective clinical study. METHOD: Horses were diagnosed with degenerative joint disease of one or more of the tarsometatarsal or distal intertarsal joints based on history, lameness examination, radiographic findings and, in some cases, response to intra-articular anaesthesia or medication. Intra-articular injections of sodium monoiodoacetate were performed using 23 gauge needles in the sedated, standing horse. Positive contrast arthrography of the distal intertarsal joint was performed in all horses to evaluate needle placement and the presence or absence of communication with other synovial structures. The mean intra-articular dose of sodium monoiodoacetate was 192 mg. Horses were subject to a graded exercise program commencing 7 to 10 days after treatment. Where possible, follow up lameness examination and radiography was performed at 3, 6, 12 and 24 months after treatment. RESULTS: At 3, 6, 12 and 24 months after treatment, respectively, 0/57, 14/55, 41/50, and 29/34 of horses were sound. At 3, 6, 12 and 24 months after treatment, respectively, 5/55, 24/38, 26/30 and 18/18 of horses had radiographic evidence of ankylosis of treated joints. Post injection pain was marked in 6.7% of horses and significant complications requiring further treatment occurred in 3.8% of horses. CONCLUSIONS: Chemical arthrodesis using sodium monoiodoacetate was an effective treatment method for degenerative joint disease of the distal tarsal joints. The technique was performed in the sedated standing horse and required minimal equipment. Results were comparable to those achieved following surgical arthrodesis. The risk of significant complications was minimised through good technique using an appropriate injection volume and concentration.     

Synoviocoeles associated with the tarsal sheath: description of the lesion and treatment in 15 horses

Reasons for performing study: To describe the presentation, clinical, ultrasonographic and endoscopic features associated with a defect in the tarsal sheath wall, to define the cavity created and to describe a method of treatment. Hypothesis: So called ‘false thoroughpins’ can be caused by defects in the tarsal sheath wall creating a one way valve effect, removal of which could be therapeutic. Methods: Case records and diagnostic images of horses with synoviocoeles associated with the tarsal sheath were reviewed retrospectively and follow‐up information obtained. Results: Synoviocoeles were diagnosed in 15 horses. All were managed similarly and 10 horses had clinical resolution and returned to work. Conclusion: Terminology previously used to describe lesions involving the tarsal sheath does not define accurately the condition described and the term synoviocoele is recommended. Endoscopic enlargement of the sheath wall defect produced good clinical results in 10/15 horses. Potential relevance: Clinicians should include synoviocoele in the list of differential diagnoses of fluid filled cavities associated with the tarsal sheath and should consider endoscopic surgery as a treatment modality.