Michael Schramme

A comparison of the effects of two volumes of local analgesic solution in the distal interphalangeal joint of horses with lameness caused by solar toe or solar heel pain.

The response of horses, with solar pain in the dorsal or palmar aspect of the foot, to 6 or 10 ml local analgesic solution administered into the distal interphalangeal (DIP) joint was examined. Lameness was induced in 7 horses by creating solar pain in the dorsal aspect of one forefoot and, at another time, the palmar aspect of the other forefoot with set-screws inserted into a custom-made shoe. Horses were videotaped trotting before and after application of set-screws and, in separate trials, after 6 or 10 ml local analgesic solution was administered into the DIP joint. Lameness scores were assigned by examining videotaped gaits. Scores were significantly lower (P < 0.05) for horses with set-screws applied to the angles of the sole and receiving 10 ml, but not 6 ml, local analgesic solution into the DIP joint. Scores were significantly lower (P < 0.05) for all horses with set-screws in the dorsal margin of the sole receiving either volume of local analgesic solution. Analgesia of the DIP joint was less effective in desensitising the angles of the sole than in desensitising the dorsal margin of the sole, and 10 ml local analgesic solution was more effective than 6 ml in desensitising these regions. The response of horses with solar pain to local analgesic solution in the DIP joint was influenced by the volume administered and the region of sole affected.

Effect of age at presentation on outcome following arthroscopic debridement of subchondral cystic lesions of the medial femoral condyle: 85 horses (1993-2003)

REASONS FOR PERFORMING STUDYnSubchondral cystic lesions of the medial femoral condyle (SCMFC) are well documented in horses < or =3 years; arthroscopic debridement or enucleation of the cyst is currently the surgical treatment of choice. However, studies of occurence and outcome following surgery in older horses are lacking.nnnOBJECTIVEnTo identify factors important in outcome for horses with SCMFC treated by arthroscopic debridement.nnnHYPOTHESISnAge of horse at presentation has a significant influence on return to work following arthroscopic treatment for SCMFC. Clinical and diagnostic findings are also significant with respect to prognosis.nnnMETHODSnA retrospective review of medical records from 6 equine referral centres identified 85 horses that underwent arthroscopic debridement of SCMFC. Clinical examination, radiographic and arthroscopic findings were analysed together with follow-up data. Univariable analysis and multivariable logistic regression models were used to determine factors affecting return to soundness. Event-time analysis was performed to evaluate return to work.nnnRESULTSnOlder horses (>3 years) were less likely to return to soundness (P = 0.02) or to work (P = 0.04) than younger horses (< or = 3 years). Of 39 horses age 0-3 years, 25 (64%, 95% CI 49-79%) returned to soundness. Of 46 horses age >3 years, 16 (35%,95% CI 21-49%) returned to soundness. In addition, cartilage damage at sites other than the SCMFC negatively affected prognosis (P = 0.05). The hospital where treatment was performed had no influence on return to soundness.nnnCONCLUSIONSnOlder horses carry a worse prognosis for both return to soundness and return to work.nnnPOTENTIAL RELEVANCEnIt is important for clients to be made aware of the difference in outcome between age groups.

An in vitro study to compare 5 different techniques for injection of the navicular bursa in the horse

Numerous different techniques for injection of the navicular bursa have been described but there is little conformity between these descriptions. A literature review was performed and techniques for injection of the navicular bursa were categorised into 5 approaches. This study was performed to evaluate the reproducibility of each technique and to assess which technique was consistently most successful. Five inexperienced operators performed each technique on 5 cadaver forelimbs. Once a needle had been placed, a radiograph was taken to confirm placement was in accordance with the description of the technique. Contrast agent was then injected and another radiograph taken to determine whether the navicular bursa had been injected successfully. The position of the navicular bone was highly predictable as a point 1 cm distal to the coronary band and halfway between the most dorsal and most palmar aspect of the coronary band. The use of this point as a landmark for injection of the navicular bursa allowed a high degree of accuracy and reliability of needle placement, irrespective of foot conformation.

Treatment of intrasynovial infection with gentamicin-impregnated polymethylmethacrylate beads

Gentamicin-impregnated polymethylmethacrylate beads were used in the treatment of infective synovitis in 12 horses and 10 cattle. They had either proved refractory to standard treatments (lavage, debridement, joint drainage and systemic antibiotics) or had evidence of osteomyelitis adjacent to a synovial cavity. All the animals were severely lame. All the cattle and six of the horses had radiological evidence of osteomyelitis in communication with a synovial cavity. The beads were placed intrasynovially under general anaesthesia and left in place for 14 days. One horse and one calf were euthanased owing to continued infective arthritis. The infection was eliminated from the other 20 cases and six of the horses returned to full athletic use. Eight of nine calves with E-type infective arthritis and osteomyelitis returned to their intended food production or breeding programmes.

A surgical tendonitis model in horses: Technique, clinical, ultrasonographic and histological characterisation

OBJECTIVEnTendon injuries are common in all athletic activities in both humans and horses. Research of treatment modalities for this disease has typically been performed on a model of collagenase-induced tendonitis. This model has several disadvantages. Our hypothesis was that a reproducible core lesion could be created surgically in superficial digital flexor tendons (SDFT), which could then be evaluated consistently using ultrasonography.nnnMATERIALS AND METHODSnFour horses free of forelimb lameness were used in this study. Each horse underwent general anaesthesia and a synovial resector was used to create a core lesion in the SDFT of each forelimb. Sonographic examination was conducted weekly using 2 cm intervals between a section 7 and 25 cm distal to the accessory carpal bone. At two, four, eight, and 12 weeks after injury, a horse was euthanatized. Histopathological evaluation of the SDFT was performed at the same levels as the sonographic examination.nnnRESULTSnOnly mild clinical signs of tendonitis were observed. Ultrasonographic core lesions were 10-16 cm long and had a mean maximum cross-sectional area (CSA) of 18.25 +/- 5.91% occurring at 17-23 cm distal to the accessory carpal bone, and a mean volume of 1.86 +/- 0.26 cm(3). Mean duration taken to achieve maximum lesion CSA and lesion volume was 35 +/- 7 days. Histologically, the lesions were characterised by mild inflammation followed by fibroplasia.nnnCONCLUSIONnThe reported surgical technique resulted in core lesions that were consistent in size and location, were readily evaluated with ultrasonography, and showed similarities with the ultrasonographic and histological progression of naturally occurring tendonitis lesions.

A comparison of the effects of local analgesic solution in the navicular bursa of horses with lameness caused by solar toe or solar heel pain

We hypothesised that analgesia of the navicular bursa is not selective for the navicular apparatus; and that solar pain in some horses can be temporarily abolished or attenuated by analgesia of the navicular bursa. To test this hypothesis, we caused lameness in horses by inducing pain in the dorsal margin or the angles of the sole and then evaluated the ability of a local analgesic solution administered into the navicular bursa to attenuate lameness. The response of horses with solar pain in the dorsal or palmar aspect of the foot to 3.5 ml local analgesic solution administered into the navicular bursa was examined. Lameness was induced in 6 horses by creating solar pain in the dorsal aspect of one forefoot and, at another time, the palmar aspect of the other forefoot, with set-screws inserted into a custom-made shoe. Horses were videotaped trotting before and after application of set-screws and after administering 3.5 ml local analgesic solution into the navicular bursa. Lameness scores were assigned by examining videotaped gaits. Scores were significantly lower (P<0.05) for all horses with set-screws applied to the dorsal margin of the sole after administration of local analgesic solution into the navicular bursa. In conclusion, analgesia of the navicular bursa was less effective in desensitising the angles of the sole than in desensitising the dorsal margin of the sole. Pain arising from the sole should not be excluded as a cause of lameness when lameness is attenuated by analgesia of the navicular bursa.

Compressive damage to the deep branch of the lateral plantar nerve associated with lameness caused by proximal suspensory desmitis.

OBJECTIVEnTo describe pathologic changes in the deep branch of the lateral plantar nerve (DBLPN) of horses determined to be lame because of proximal suspensory desmitis (PSD), and to report the outcome after treatment by excision of a segment of the horses DBLPN.nnnSTUDY DESIGNnRetrospective case series.nnnANIMALSnAdult horses (n=16).nnnMETHODSnHorses determined to be lame on one or both pelvic limbs because of PSD were treated by excision of a segment of the DBLPN, and 30 nerves were examined histologically. Owners were contacted to obtain information about the horses >or=6 months after surgery.nnnRESULTSnHistologic changes suggestive of chronic nerve compression were identified in both nerves of 11 bilaterally lame horses and in the lame limb of 5 unilaterally lame horses. The nerve of the sound limb of 2 of 3 unilaterally lame horses that had bilateral nerve resection also had histologic changes compatible with nerve compression. Ten of 16 horses (62.5%) with follow-up information returned to soundness after excision of the DBLPN.nnnCONCLUSIONSnPathologic changes of the DBLPN associated with compression may complicate PSD of the pelvic limbs. Excision of the nerve may resolve lameness caused by PSD.nnnCLINICAL RELEVANCEnHorses lame because of PSD of the pelvic limb may remain lame after desmitis has resolved because of compression of the DBLPN. Excising a portion of this nerve may resolve lameness.

Use of a bioabsorbable implant for the repair of severed digital flexor tendons in four horses.

A new bioabsorbable implant composed of poly-L-lactic acid was used to repair the severed digital flexor tendons of four horses. The limbs were immobilised with distal casts which were changed after six to eight weeks and removed after 12 to 16 weeks. The horses were followed clinically and ultrasonographically for from seven to 19 months after the surgery. The ultrasonographic examination after the cast had been removed showed that the implants had been well incorporated into scar tissue. Two of the horses were mildly lame at the trot seven months after the surgery, but had returned to work after 12 months. The other two horses are still lame. No complications were observed with the implant.

Tendon injury in the horse: current theories and therapies

TENDON injuries can arise by either intrinsic (strain or displacement) or extrinsic (bruise, penetration or laceration) mechanisms, and appear to be widespread in the horse. The most frequently observed injury is the strain injury which predominantly affects the palmar soft tissue structures which support the metacarpophalangeal joint. This article discusses the rational treatment of tendonitis based on current knowledge of pathophysiological events in the injured tendon. Given that injured tendons heal by repair rather than regeneration, prevention must be the ultimate goal and, to this end, four strategies for the prevention of tendonitis are proposed.

Effect of anesthetizing individual compartments of the stifle joint in horses with experimentally induced stifle joint lameness

OBJECTIVEnTo evaluate the effects of sequential anesthesia of the individual compartments of the equine stifle joint on lameness induced by intra-articular deposition of interleukin (IL)-1β.nnnANIMALSn6 horses.nnnPROCEDURESnFor each horse, baseline hind limb lameness was first evaluated. A randomly selected compartment of 1 stifle joint was then injected with IL-1β to induce synovitis and lameness; subsequently, the same compartment was anesthetized with 2% mepivacaine hydrochloride, and lameness was reevaluated. Two weeks later, baseline lameness was evaluated, and lameness was similarly induced; thereafter, the 2 synovial compartments of the stifle joint not injected with IL-1β were anesthetized sequentially in random order (ie, first and second blocks); lameness was evaluated after each block. Finally, the IL-1β-treated compartment was anesthetized (third block); lameness was again evaluated. This second experiment was repeated for the contralateral stifle joint 2 weeks later. Throughout the study, lameness was quantified objectively by assessing vertical pelvic movement asymmetry with a wireless, inertial sensor-based system.nnnRESULTSnIntra-articular deposition of IL-1β induced lameness in all injected limbs. In the first experiment, anesthesia of the compartment injected with IL-1β resulted in a significant decrease in lameness, with vertical pelvic movement asymmetry approaching baseline. In the second experiment, lameness improved significantly after the second and third blocks and was almost completely abolished after all 3 synovial compartments were anesthetized.nnnCONCLUSIONS AND CLINICAL RELEVANCEnIn horses, lameness caused by a lesion in 1 compartment of a stifle joint can be improved more by instillation of local anesthetic solution into that compartment than by anesthesia of the other compartments.