Evaluation of analgesia resulting from extracorporeal shock wave therapy and radial pressure wave therapy in the limbs of horses and sheep

OBJECTIVE: To identify the duration and potential mechanisms of analgesia following extracorporeal shock wave therapy (ESWT) and radial pressure wave therapy (RPWT) in limbs of horses and sheep. ANIMALS: 6 horses and 30 sheep. PROCEDURE: An electrical stimulus was used to identify the nociceptive threshold for each horse daily for 3 days before treatment (baseline) with ESWT or RPWT, 8 hours after treatment, and at 24-hour intervals for 7 days after treatment. Testing was conducted for the treatment field (midmetacarpus or midmetatarsus) and nerve field (medial and lateral forelimb heel bulbs) distal to a treatment site that included the nerve on the abaxial surface of the proximal sesamoid bone. All 4 limbs of 30 sheep were treated with ESWT, RPWT, or a sham treatment. Two sheep were euthanatized daily and tissue harvested for histologic evaluation of nerves, and concentrations of substance P and calcitonin gene-related peptide were measured in the skin and periosteum. RESULTS: Values did not differ significantly between baseline and after treatment for the treatment field or nerve field sensation. There was a large difference in the slope when data for horses were plotted for the first 3 days after treatment, compared with the slope for days 4 to 7 after treatment. No differences were found in neuropeptide concentrations after treatment of the sheep, but there was an inflammatory response in the treated nerves. CONCLUSIONS AND CLINICAL RELEVANCE: A small cutaneous analgesic effect may exist at the treatment site for approximately 3 days after ESWT or RPWT in horses.     

Effects of extracorporeal shock wave therapy and radial pressure wave therapy on elasticity and microstructure of equine cortical bone

OBJECTIVE: To measure changes in the modulus of elasticity (E) and describe histologic findings after extracorporeal shock wave therapy and radial pressure wave therapy on equine cortical bone specimens. SAMPLE POPULATION: 16 bone specimens from the proximodorsal cortex of an equine third metacarpal or metatarsal bone. PROCEDURE: Baseline E was determined by the density (p) and unidirectional ultrasound transmission velocity (C) of each specimen according to the equation E = pC2. Eight specimens were treated with 500 pulses of 0.15 mJ/mm2 of extracorporeal shock wave therapy, and 8 specimens were treated with 500 pulses of 0.16 mJ/mm2of radial pressure wave therapy. After treatment, C was determined again. Four treatment sessions resulted in 2,000 pulses and 5 C measurements. The p of each sample was measured again. Mean post-treatment E was calculated for each group. Nondecalcified sections of all specimens were stained with toluidine blue or basic fuchsin for histologic evaluation. RESULTS: Overall treatment group effect was not significant for C or E. Final E was not different from baseline values for extracorporeal shock wave therapy and radial pressure wave therapy. No histologic changes could be attributed to either treatment modality. CONCLUSIONS AND CLINICAL RELEVANCE: Extracorporeal shock wave therapy and radial pressure wave therapy did not affect the material properties of equine bone at the energy and pulse values used in this study.     

Immunohistochemical localization of substance P,calcitonin gene-related peptide,galanin and calcium-binding proteins in trigeminal ganglia of goat (Capra hircus)

The objectives of this study was to provide a quantitative analysis of calcium-binding proteins, calbindin (CB), parvalbumin (PA), substance P (SP), calcitonin gene-related peptide (CGRP) and galanin (GAL), in trigeminal ganglia of goats, to establish whether they exhibit coexistence relationships between each other, and to examine possible colocalization with SP, CGRP and GAL, which have been well characterized according to their distributions in an abundance of large and/or small neurones. CB (12.78%), PA (31.91%), SP (24.63%), CGRP (44.44%) and GAL (3.29%) immunoreactive (IR) cells were observed. About 38.37, 8.7 and 0.73% of CGRP-IR neurones in the trigeminal ganglion were also immunoreacted with SP, GAL and CB, respectively. Almost all SP-IR cells are labelled with CGRP (approximately 92.52%), whereas only 16.02 and 0.44% of SP-IR neurones colocalized with GAL and CB. Approximately 4.65 and 1.10% of the CB-IR cells were found to contain CGRP and SP immunoreactivity, respectively. Conversely, no CB-IR cell exhibited GAL immunoreactivity. In addition, all the GAL-IR cells showed CGRP and SP immunoreactivity. The number of CB-, PA-, SP-, CGRP- and GAL-IR neurones in goat trigeminal ganglion are abundant than that of other animals. These results elucidate that the goat differs from other mammalian species in the distribution and localization of neurochemical substances in trigeminal ganglia, and suggest that this difference may be relevant to the morphological characteristics of cerebral vasculatures such as epidural rete mirabile of goat.     

Effect of focused and radial extracorporeal shock wave therapy on equine bone microdamage

OBJECTIVES : To determine whether bone microcracks are altered after application of focused and radial extracorporeal shock wave therapy (ESWT) to the equine distal limb. STUDY DESIGN : An ex vivo experimental model. SAMPLE POPULATION : A contralateral limb specimen was obtained from 11 Thoroughbred racehorses with a unilateral catastrophic injury. Distal limb specimens were also obtained from 5 non-racing horses. METHODS : Three separate skin-covered bone segments were obtained from the mid-diaphysis of the metacarpus (MC3) or metatarsus (MT3). Focused (9,000 shockwaves, 0.15 mJ/mm2, 4 Hz) and radial (9,000 shockwaves, 0.175 mJ/mm2, 4 Hz) ESWT treatments were randomized to the proximal and distal segments and the middle segment was used as a treatment control for pre-existing microcracks. After treatment, bone specimens were bulk-stained with basic fuchsin and microcracks were quantified in transverse calcified bone sections. RESULTS : ESWT had small but significant effects on microcracks. Microcrack density (Cr.Dn) and microcrack surface density (Cr.S.Dn) were increased after focused ESWT, whereas Cr.Le was increased after radial ESWT. In racing Thoroughbreds, Cr.Le increased with increased number of races undertaken. Cr.Dn and Cr.S.Dn were not significantly influenced by the number of races undertaken. CONCLUSION : ESWT has small but significant effects on bone microcracking ex vivo. CLINICAL RELEVANCE : These preliminary data suggest that ESWT has the potential to increase bone microcracking in equine distal limb bone in vivo. Such effects may be more pronounced in Thoroughbreds that are actively being raced, because in vivo microcracking increases with increased number of races undertaken.     

The coexistence of calcitonin gene-related peptide and substance P in pericellular arborization and satellite cell of goat trigeminal and nodose ganglia

Pericellular arborization is reported to be the self-regulating structure in sensory ganglia. Although the calcitonin gene-related peptide (CGRP) or substance P (SP) immunoreactive pericellular arborization appeared in the sensory ganglia, there was no available information that CGRP and SP colocalize in this structure. As the attempts to resolve the question described above, the present study was undertaken to identify the coexistence of CGRP and SP in pericellular arborizations of the goat nodose and trigeminal ganglia by double immunohistochemistry. As the results show, CGRP immunoreactivity was present in every pericellular arborization containing SP immunoreactivity in trigeminal ganglia, however, pericellular network containing CGRP or SP immunoreactivity was not present in nodose ganglia. Unexpectedly, a few small satellite elements were observed to contain intense CGRP and SP immunoreactivity at the periphery of CGRP and SP immunoreactive neurones in nodose ganglia. Therefore, these results suggest that CGRP and SP coexist in pericellular arborizations, and that satellite cell as well as pericellular arborization may be involved in intraganglionic regulation of goat sensory ganglia.     

Distribution of substance P and calcitonin gene-related peptide in the spinal cord of Cavalier King Charles Spaniels affected by symptomatic syringomyelia

The causes of clinical signs associated with syringomyelia in the Cavalier King Charles Spaniel (CKCS) are incompletely understood. In this study we compared expression of two pain-related neuropeptides: substance P (SP) and calcitonin gene related peptide (CGRP), in the spinal cord dorsal horn of normal dogs with that in CKCS with and without clinical signs of syringomyelia. There was a decrease in expression of both peptides in CKCS with 'symptomatic' syringomyelia that was also associated with significant asymmetry in SP-I and similar, though non-significant, asymmetry in CGRP-I compared with other groups. The asymmetric distribution of these pain-related peptides may be a consequence of syrinx-associated damage to grey matter but may also play a role in generation of pain.     

The distribution of nerve fibres immunoreactive for vasoactive intestinal peptide, calcitonin gene-related peptide, substance P and dopamine beta-hydroxylase in the normal equine larynx

The autonomic innervation of the mammalian respiratory system is complex, and involves a wide variety of peptide and non-peptide neurotransmitters which will have an important role in normal laryngeal function and the response to disease. This innervation has been partially described in the horse airway and lung, but there is no information on the equine larynx. This paper describes the expression and distribution of nerve fibres immunoreactive for vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), substance P (SP) and the adrenergic enzymatic marker dopamine beta-hydroxylase (DBetaH) in the mucosa of the equine larynx. The overall relative density of nerve fibres immunoreactive for the different antigens was VIP>CGRP>SP>DBetaH. There were differences in the distribution of nerve fibre types, although each antigen was found in nerve fibres adjacent to blood vessels and mucous glands. VIP -like immunoreactivity (VIP -Li) was particularly extensive in association with mucous glands. SP - and CGRP -like immunoreactivity (SP -Li, CGRP -Li) were also seen close to the epithelium, with occasional nerve fibres coursing beneath and between the epithelial cells. Fragments of SP -Li and CGRP -Li fibres were also present in large nerve fibre bundles and ganglionic cell clusters, but not in the neurons themselves. The density of nerve fibres immunoreactive for DBetaH was very low and restricted to blood vessels and mucous glands. There was marked variation in the density of nerve fibres at the different sites, with the greatest density, particularly for VIP, over the arytenoid cartilage. Immunoreactive nerve fibres were less plentiful over the epiglottis, and the density of all types of nerve fibres was low over the cricoid cartilage. Overall VIP -Li nerve fibres were the most plentiful.     

Expression of vasoactive intestinal peptide, calcitonin gene-related peptide, substance P, and intermediate neurofilaments in nasal mucosal nerve fibers of horses without nasal disease

OBJECTIVE: To determine the distribution of nerve fibers containing calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), and intermediate neurofilaments in nasal mucosa of horses. ANIMALS: 6 horses without evidence of nasal disease. PROCEDURE: Full-thickness nasal tissue specimens were obtained from the rostral portion of the nasal septum at necropsy, and fluorescence immunohistochemistry was performed to assess mucosal distribution of nerve fibers. RESULTS: Nerve fibers with CGRP-like immunoreactivity (CGRP-Li) formed a dense subepithelial network, and a large number of fibers were found coursing between epithelial cells. Fibers with CGRP-Li were also associated with blood vessels and mucous glands. Fibers with SP-like immunoreactivity (SP-Li) had a similar distribution and density. In contrast, there were few fibers with VIP-like immunoreactivity. Fibers containing intermediate neurofilaments were prominent and appeared as large nerve fiber bundles mainly adjacent to the nasal septum but also close to mucous glands and within the lamina propria. Intermediate neurofilaments were also identified in single nerve fibers at all sites, but the density of fibers with intermediate neurofilaments did not match that of fibers with CGRP- or SP-Li. CONCLUSIONS: The density and distribution of nerve fibers containing SP- or CGRP-Li in nasal mucosa of horses was similar to that reported for other species. However, expression of VIP in nerve fibers was low. Antibodies against intermediate neurofilaments identified many nerve fibers in nasal mucosa of horses but did not appear to identify small diameter fibers expressing SP or VIP.     

Force platform evaluation of lameness severity following extracorporeal shock wave therapy in horses with unilateral forelimb lameness

OBJECTIVE: To measure alterations in lameness severity that occur following use of extracorporeal shock wave therapy (ESWT) in horses with naturally occurring unilateral forelimb lameness. DESIGN: Nonrandomized clinical trial. ANIMALS: 9 horses with unilateral forelimb lameness. PROCEDURES: Force platform gait analysis was performed prior to administration of any treatments (baseline) and after use of local anesthesia to eliminate the lameness. Extracorporeal shock wave therapy was then administered, and gait analysis was repeated 8 hours later and then daily for 7 days. RESULTS: Compared with the baseline value, peak vertical force was significantly increased 8 hours and 2 days after ESWT, and peak vertical force on day 2 was not significantly different from force measured after use of local anesthesia to eliminate the lameness. Similarly, vertical impulse was significantly increased, compared with the baseline value, 8 hours and 2 days after ESWT, but at all times, it was significantly lower than vertical impulse measured after use of local anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses with naturally occurring lameness, use of ESWT results in a period of acute improvement in lameness severity that typically persists for 2 days. Thus, in horses undergoing ESWT, exercise should be controlled for a minimum of 2 days after treatment to prevent further injury.     

Evaluation of skin sensitivity after shock wave treatment in horses

OBJECTIVE: To evaluate the effects of shock wave treatment on cutaneous nerve function, compared with the effects of local nerve block and sedation. ANIMALS: 18 clinically sound Swiss Warmbloods. PROCEDURE: Horses were randomly allocated to 3 groups and received different amounts and types of shock waves (extracorporeal shock wave treatment [ESWT] or radial pressure wave treatment [RPWT]). Horses were sedated with xylazine and levomethadone. Shock waves were applied to the lateral palmar digital nerve at the level of the proximal sesamoid bones on 1 forelimb. Skin sensitivity was evaluated by means of an electrical stimulus at the coronary band before and 5 minutes after sedation and at 4, 24, and 48 hours after application of ESWT or RPWT. On the contralateral forelimb, skin sensitivity was tested before and 10 minutes after an abaxial sesamoid nerve block. RESULTS: No significant changes in skin sensitivity were detected, regardless of the shock wave protocol applied. Mean reaction thresholds after sedation were more than twice the baseline thresholds. After the abaxial sesamoid block, no reaction was recorded in any of the horses. CONCLUSIONS AND CLINICAL RELEVANCE: Application of ESWT or RPWT to the palmar digital nerve had no effect on cutaneous sensation distal to the treated region for at least 2 days after application. The analgesic effect of sedation on reaction to electrical stimuli was distinct but varied among horses.     

Histomorphologic evaluation of extracorporeal shock wave therapy of the fourth metatarsal bone and the origin of the suspensory ligament in horses without lameness

OBJECTIVE: To determine via histologic examination and scintigraphy the effect of focused extracorporeal shock wave therapy (ESWT) on normal bone and the bone-ligament interface in horses. ANIMALS: 6 horses without lameness. PROCEDURE: Origins of the suspensory ligament at the metacarpus (35-mm probe depth) and fourth metatarsal bone (5-mm probe depth) were treated twice (days 0 and 16) with 2,000 shocks (energy flux density, 0.15 mJ/mm2). One forelimb and 1 hind limb were randomly treated, and the contralateral limbs served as nontreated controls. Bone scans were performed on days -1 (before ESWT), 3, 16, and 19. Histomorphologic studies of control and treated tissues were performed on day 30. RESULTS: ESWT significantly increased the number of osteoblasts but caused no damage to associated soft tissue structures and did not induce cortical microfractures. A significant correlation between osteoblast numbers and radiopharmaceutical uptake was noticed on lateral views of the hind limb on days 3 and 16 and on caudal views of the forelimb on day 3. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that ESWT has the potential to increase osteoblast numbers in horses. The correlation between increased osteoblast numbers and radio-pharmaceutical uptake 3 days and 16 days after the first ESWT suggested that stimulation of osteogenesis occurred soon after ESWT. No damage to bone or the bone-ligament interface should occur at the settings used in this study, and ESWT can therefore be administered safely in horses.     

Innervation pattern of substance P- and calcitonin gene-related peptide-immunoreactive nerves of the cerebral arteries in the quail

The pattern of cerebrovascular substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactive (IR) innervation was investigated in the quail. SP- and CGRP-IR nerves were relatively a few in the rostral part of the anterior circulation, and very scanty or lacking in its caudal part and the whole of the posterior circulation. A significant finding was that the anterior circulation in the majority of individuals is furnished with a varying proportion of SP-IR nerves with or without CGRP immunoreactivity. There was a good correlation in the expression of CGRP immunoreactivity between SP-IR cells in the ophthalmic division of the trigeminal ganglion and SP-IR nerves supplying the major cerebral arteries. In the quail, SP- and CGRP-IR fiber bundles are usually present in the internal ethmoidal artery (IEA). From these and other findings, it is most probable that cerebral perivascular SP- and CGRP-IR nerves are mainly derived from the same categories of neurons in the primary sensory ganglion via the IEA. The close association of varicose SP-IR axons to the nerve cells in the pial arteries suggests that these intrinsic neurons may play some vasocontrolling roles through the modulatory effect of their pericellular SP-IR axons.     

Determination of functional and morphologic changes in palmar digital nerves after nonfocused extracorporeal shock wave treatment in horses

OBJECTIVE: To determine functional and morphologic changes in palmar digital nerves after nonfocused extracorporeal shock wave (ESW) treatment in horses. ANIMALS: 6 horses. PROCEDURES: The medial and lateral palmar digital nerves of the left forelimb were treated with nonfocused ESWs. The medial palmar digital nerve of the right forelimb served as a nontreated control nerve. At 3, 7, and 35 days after treatment, respectively, 2 horses each were anesthetized and nerves were surgically exposed. Sensory nerve conduction velocities (SNCVs) of treated and control nerves were recorded, after which palmar digital neurectomies were performed. Morphologic changes in nerves were assessed via transmission electron microscopy. RESULTS: Significantly lower SNCV in treated medial and lateral nerves, compared with control nerves, was found 3 and 7 days after treatment. A significantly lower SNCV was detected in treated medial but not lateral nerves 35 days after treatment. Transmission electron microscopy of treated nerves revealed disruption of the myelin sheath with no evidence of damage to Schwann cell bodies or axons, 3, 7, and 35 days after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Nonfocused ESW treatment of the metacarpophalangeal area resulted in lower SNCV in palmar digital nerves. This effect likely contributes to the post-treatment analgesia observed in horses and may result in altered peripheral pain perception. Horses with preexisting lesions may be at greater risk of sustaining catastrophic injuries when exercised after treatment.     

The effect of focused extracorporeal shock wave therapy on collagen matrix and gene expression in normal tendons and ligaments

Reasons for performing study: Extracorporeal shock wave therapy (ESWT) is frequently used in equine practice, but little is known about its biological action. Objectives: To study the effects of ESWT on matrix structure and gene expression levels in normal, physiologically loaded tendinous structures in ponies. Methods: Six Shetland ponies, free of lameness and with ultrasonographically normal flexor and extensor tendons and suspensory ligaments (SL), were used. ESWT was applied at the origin of the suspensory ligament and the mid‐metacarpal region of the superficial digital flexor tendon (SDFT) 6 weeks prior to sample taking, and at the mid‐metacarpal region (ET) and the insertion on the extensor process of the distal phalanx (EP) of the common digital extensor tendon 3 h prior to tendon sampling. In all animals one forelimb was treated and the other limb was used as control. After euthanasia, tendon tissue was harvested for real‐time PCR to determine gene expression levels and additional samples were taken for histological evaluation and biochemical analyses Results: Histologically a disorganisation of the normal collagen structure was observed 3 h after ESWT, remnants of which were still visible after 6 weeks. While degraded collagen levels showed an increase at 3 h post treatment (P = 0.012) they were reduced at 6 weeks post ESWT (P = 0.039). Gene expression for both COL1 (P = 0.004) and MMP14 (P = 0.020) was upregulated at 6 weeks after treatment. Conclusions: Exposure of normal tendinous tissue to ESWT is not uneventful; it leads to a disorganisation of matrix structure and changes in degraded collagen levels. The upregulation of COL1 expression 6 weeks after ESWT may be indicative for repair. Potential relevance: The observed disorganisation of the collagen network warrants caution when using ESWT. Exposing noninjured tissue to ESWT should be avoided and it may be advisable to restrict exercise in recently treated patients. However, the induced tissue disorganisation might also be a trigger for repair in chronic tendinopathies.     

Investigation of the immediate analgesic effects of extracorporeal shock wave therapy for treatment of navicular disease in horses

OBJECTIVES: To measure the acute analgesic properties of extracorporeal shock wave therapy (ESWT) in horses with navicular disease using objective ground reaction forces (GRF). STUDY DESIGN: Prospective study. ANIMALS: Nine client-owned horses with unilateral forelimb lameness caused by navicular disease. METHODS: Horses were trotted at 3 m/s over a force plate to record pre-treatment GRF of the lame and contra-lateral forelimbs. After ESWT of the lame limb, applied with a radial unit to each of the frog and heel bulb areas with 1500 pulses at 4 bar and 10 Hz, GRF measurements were repeated at 15 minutes and 24-hour intervals for 7 days. From the 5 trials recorded at each time, peak vertical force (PVF) was calculated and averaged. Data were compared between limbs and over time using a 2-way repeated-measures ANOVA. RESULTS: Mean (+/-SD) PVF was significantly different between lame (day 1; 4339+/-626 N) and contra-lateral (day 1; 5236+/-515 N) limbs pre-treatment (P<.05). After ESWT treatment, this difference remained unchanged at 15 minutes and from days 1 to 7. To confirm navicular disease, palmar digital analgesia significantly reduced the lameness (lame 5144+/-430 N; contralateral 5082+/-586 N; P>.05). CONCLUSIONS: Single ESWT treatment applied in this manner does not influence lameness in horses with navicular disease. CLINICAL RELEVANCE: Although many equine regulatory commissions currently ban the use of ESWT before competition, our results suggest that such regulations may be unfounded. Further research is required to determine the long-term analgesic properties of this frequently used treatment modality in equine athletes.     

Treatment of chronic or recurrent proximal suspensory desmitis using radial pressure wave therapy in the horse

REASONS FOR PERFORMING STUDY: Proximal suspensory desmitis (PSD) is diagnosed with increasing frequency in horses and radial pressure wave therapy (RPWT) is a widely used therapy for painful orthopaedic conditions in man and dogs. There are, however, few published data as to the outcome of its use in PSD. OBJECTIVE: To evaluate the use of RPWT in the treatment of chronic or recurrent PSD in the horse, an injury which carries a poor prognosis for return to athletic function with conservative management alone. HYPOTHESIS: RPWT and controlled exercise improves the prognosis of chronic or recurrent PSD in the horse when compared to previously published results of controlled exercise alone. METHODS: The use of RPWT in the management of chronic or recurrent proximal suspensory desmitis (PSD) was evaluated in 65 horses. Diagnosis was based on response to local analgesia, ultrasonography and radiography. Horses were classified according to severity of ultrasonographic lesions, whether fore- or hindlimbs were affected, and duration of lameness prior to diagnosis. Horses were treated 3 times at 2-week intervals and followed a controlled exercise programme; they were reassessed clinically and ultrasonographically 10-12 weeks after diagnosis, when further exercise recommendations were made dependent upon the animal's progress. RESULTS: Forty-one percent of horses with hindlimb lameness and 53% with forelimb lameness were nonlame and returned to full work 6 months after diagnosis. The prognosis was significantly affected by the ultrasonographic grade at the time of diagnosis and by ultrasonographic evidence of resolution of the lesion in hindlimb cases. CONCLUSIONS: These findings, when compared to previously published results of treatment using controlled exercise alone, suggest that RPWT improves the prognosis for PSD in the hindlimb. POTENTIAL RELEVANCE: RPWT is a useful treatment modality for chronic or recurrent PSD when combined with controlled exercise. Further studies are required on the effect of RPWT employing histology and biomechanics in order to fully evaluate its use on equine tissues.     

Effect of extracorporeal shock wave therapy on the biochemical composition and metabolic activity of tenocytes in normal tendinous structures in ponies

REASONS FOR PERFORMING STUDY: Extracorporeal shockwave therapy (ESWT) has recently been introduced as a new therapy for tendon injuries in horses, but little is known about the basic mechanism of action of this therapy. OBJECTIVES: To study the effect of ESWT on biochemical parameters and tenocyte metabolism of normal tendinous structures in ponies. METHODS: Six Shetland ponies, free of lameness and with ultrasonographically normal flexor and extensor tendons and suspensory ligaments (SL), were used. ESWT was applied at the origin of the suspensory ligament and the mid-metacarpal region of the superficial digital flexor tendon (SDFT) 6 weeks prior to sample taking, and at the mid-metacarpal region (ET) and the insertion on the extensor process of the distal phalanx (EP) of the common digital extensor tendon 3 h prior to tendon sampling. In all animals one front leg was treated and the other front leg was used as control. After euthanasia, tendon explants were harvested aseptically for in vitro cell culture experiments and additional samples were taken for biochemical analyses. RESULTS: In the explants harvested 3 h after treatment, glycosaminoglycan (GAG) and protein syntheses were increased (P<0.05). The synthesis of all measured parameters was decreased 6 weeks after ESWT treatment. Biochemically, the level of degraded collagen was increased 3 h after treatment (P<0.05). Six weeks after treatment, there was a decrease of degraded collagen and GAG contents. DNA content had not changed in either tendon samples or explants after culturing. CONCLUSIONS: ESWT causes a transient stimulation of metabolism in tendinous structures of ponies shortly after treatment. After 6 weeks metabolism has decreased significantly and GAG levels are lower than in untreated control limbs. POTENTIAL RELEVANCE: The stimulating short-term effect of ESWT might accelerate the initiation of the healing process in injured tendons. The long-term effect seems less beneficial. Further research should aim at determining the duration of this effect and at assessing its relevance for end-stage tendon quality.     

Evaluation of cutaneous analgesia after non-focused extracorporeal shock wave application over the 3rd metacarpal bone in horses

Extracorporeal shock wave therapy is becoming increasingly used in equine practice to treat musculoskeletal disorders. Although the exact effects of extracorporeal shock waves on tissues still need to be elucidated, transient cutaneous analgesia has been observed within treated areas in humans and horses. The purpose of this study was to determine the onset, magnitude, and duration of cutaneous analgesia after non-focused extracorporeal shock wave (ESW) application by comparing the limb withdrawal reflex latency (LWRL) in treated and untreated areas on the metacarpus of horses, using a focused light source. A single treatment with non-focused ESW was applied to 3 areas over the dorsal aspect of one metacarpus in 12 horses. The LWRL was measured to assess cutaneous sensation in treated and untreated control areas of the treated metacarpus and in an untreated area on the opposite metacarpus, before and at various time points after ESW application. Most treated and control areas revealed a significant decrease in LWRL over time compared with baseline values. Although the results of our study do not suggest cutaneous analgesia after ESW application to the equine metacarpus, we advise cautious use of this treatment modality for horses in training or before competition until further research is done.     

Short term analgesic effect of extracorporeal shock wave therapy in horses with proximal palmar metacarpal/plantar metatarsal pain

Extracorporeal shock wave therapy (ESWT) is an accepted form of treatment for chronic cases of proximal suspensory desmitis (PSD). Subjective evaluation of horses shortly after being treated with ESWT has led clinicians to comment on an immediate reduction in lameness. This study aimed to evaluate the analgesic effect of ESWT on 16 horses with PSD or PSD-like pain in a fore- or hindlimb. To objectively assess lameness, gait analysis was performed on an instrumented treadmill before and 6, 24, 48 and 72h after ESWT of the origin of the suspensory ligament and the results compared to the effects of local anaesthesia. Stride frequency, stance duration, vertical impulse and peak vertical force were determined. Thermographic imaging and evaluation of skin sensitivity of the treated area were carried out before and after ESWT in the same interval as gait analysis. The results showed that there were no significant improvements in the investigated parameters at any time after ESWT; however, in horses with affected forelimbs the contralateral weightbearing asymmetry decreased significantly 72h after ESWT. Neither skin sensitivity nor thermographic imaging revealed changes that could be attributed to ESWT.