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OBJECTIVE To describe outcomes of horses with temporohyoid osteoarthropathy (THO) treated with partial ceratohyoidectomy. ANIMALS 10 client-owned horses PROCEDURES Medical records from 2 institutions were examined for records of horses with THO treated with partial ceratohyoidectomy between 2010 and 2021. History, signalment, clinical signs, diagnostics, medications, and surgery-related details were recorded. Horses with a minimum of 6 months follow-up were recruited for neurologic and imaging examinations in the hospital or field where radiography of the basihyoid-ceratohyoid articulation were performed along with CT, when available. RESULTS 10 horses with THO were included (9 unilateral; 1 bilateral). Nine planned partial ceratohyoidectomies were performed in 8 horses, whereas 2 horses had preoperatively planned complete ceratohyoidectomies transitioned to partial ceratohyoidectomies during surgery due to intraoperative complications. Postoperative complications occurred mostly in transitioned surgeries (obstructed airway, tongue mobility issues, and incisional hemorrhage), whereas only 1 horse with a planned ceratohyoidectomy had postoperative complication of rhabdomyolysis. All complications resolved before hospital discharge. Neurologic signs improved in all 10 horses, with 2 showing complete resolution. Nine horses were available for radiographic follow-up, 6 of which also had head CT scans. A space between the ceratohyoid and basihyoid bones was measurable on radiography in all 9 horses, and was confirmed on CT. Three horses demonstrated proliferation of either ceratohyoid or basihyoid bones. The 9 horses with unilateral disease returned to previous work, and the horse with bilateral disease was retired. CLINICAL RELEVANCE Partial ceratohyoidectomy is a surgical option for treatment of THO that provides similar clinical outcomes to published reports on ceratohyoidectomy.

Background Local anaesthetics are being combined clinically with amikacin in intravenous regional limb perfusion (IVRLP), with limited knowledge on the analgesia provided and its onset and duration of action after tourniquet application and release. Objective To evaluate the systemic clinical effect, limb withdrawal to nociceptive stimulation, and plasma and synovial fluid concentrations after IVRLP with lidocaine or mepivacaine in standing sedated horses. Study design Prospective, controlled, randomised, cross-over study. Methods Six healthy adult horses were sedated and received IVRLP with lidocaine, mepivacaine or saline (negative control), or perineural anaesthesia of the medial and lateral palmar and palmar metacarpal nerves (positive control) in one forelimb with a 3-week washout period between trials. Electrical and mechanical stimuli were used to test nociceptive threshold of the limb before and after IVRLP/perineural anaesthesia. For lidocaine and mepivacaine trials, blood was collected from the jugular vein and synovial fluid from the radiocarpal joint before, during and out to 24 hours after IVRLP. Drug concentrations were measured using high-performance liquid chromatography. Results Nociceptive thresholds for lidocaine, mepivacaine and perineural anaesthesia trials were significantly increased compared with saline and baseline values at 10, 20 and 30 minutes, with no differences between anaesthetic trials. During this time, horses had lower heart rates than IVRLP with saline. After tourniquet release at 30 minutes, nociceptive thresholds for lidocaine and mepivacaine trials gradually returned to baselines, whereas perineural anaesthesia trial remained unchanged out to an hour. Plasma lidocaine and mepivacaine concentrations were ≤50 ng/mL while the tourniquet was in place, significantly increasing 10 minutes after tourniquet release. Maximal lidocaine and mepivacaine concentrations in synovial fluid were reached 25 minutes after IVRLP injection. Main limitations Amikacin was not included in the perfusate. Conclusion Similar to perineural anaesthesia, IVRLP with lidocaine or mepivacaine provides anti-nociception to the distal limb in standing sedated horses while a tourniquet is applied with concentrations remaining below toxic levels in plasma and synovial fluid.

BACKGROUND: Osteoarthritis (OA) of the distal intertarsal (DIT) and tarsometatarsal (TMT) joints occurs commonly. Synovial fluid (SF) biomarkers of collagen and bone turnover have potential clinical value. OBJECTIVES: To measure SF biomarker concentrations from DIT and TMT joints in adult horses and determine if they correlate with radiographic OA severity and are higher in joints with radiographic OA compared to controls. STUDY DESIGN: Cross‐sectional. METHODS: Radiographic OA of DIT and TMT joints was evaluated from adult horses (5–35 years old). Overall radiographic scores divided horses into those with mild or moderate radiographic OA (16 joints from 9 horses) or controls (13 joints from 9 horses). Direct biomarkers of OA (Carboxypropeptide of type II collagen = CPII, carboxy‐neoepitope of type II collagen exposed after collagenase‐cleavage = C2C, Bone alkaline phosphatase = BAP and Chondroitin sulfate epitope = CS846) were measured via ELISA and CPII/C2C was calculated. Biomarkers were correlated with radiographic findings and concentrations from those with radiographic OA to control joints and were compared. RESULTS: Concentrations of CPII (R = 0.84, P

Background:Plyometric exercise is used during rehabilitation after anterior cruciate ligament (ACL) reconstruction to facilitate the return to sports participation. However, clinical outcomes have not been examined, and high loads on the lower extremity could be detrimental to knee articular cartilage.Purpose:To compare the immediate effect of low- and high-intensity plyometric exercise during rehabilitation after ACL reconstruction on knee function, articular cartilage metabolism, and other clinically relevant measures.Study Design:Randomized controlled trial; Level of evidence, 2.Methods:Twenty-four patients who underwent unilateral ACL reconstruction (mean, 14.3 weeks after surgery; range, 12.1-17.7 weeks) were assigned to 8 weeks (16 visits) of low- or high-intensity plyometric exercise consisting of running, jumping, and agility activities. Groups were distinguished by the expected magnitude of vertical ground-reaction forces. Testing was conducted before and after the intervention. Primary outcomes were self-reported knee function (International Knee Documentation Committee [IKDC] subjective knee form) and a biomarker of articular cartilage degradation (urine concentrations of crosslinked C-telopeptide fragments of type II collagen [uCTX-II]). Secondary outcomes included additional biomarkers of articular cartilage metabolism (urinary concentrations of the neoepitope of type II collagen cleavage at the C-terminal three-quarter–length fragment [uC2C], serum concentrations of the C-terminal propeptide of newly formed type II collagen [sCPII]) and inflammation (tumor necrosis factor–α), functional performance (maximal vertical jump and single-legged hop), knee impairments (anterior knee laxity, average knee pain intensity, normalized quadriceps strength, quadriceps symmetry index), and psychosocial status (kinesiophobia, knee activity self-efficacy, pain catastrophizing). The change in each measure was compared between groups. Values before and after the intervention were compared with the groups combined.Results:The groups did not significantly differ in the change of any primary or secondary outcome measure. Of interest, sCPII concentrations tended to change in opposite directions (mean ± SD: low-intensity group, 28.7 ± 185.5 ng/mL; high-intensity group, −200.6 ± 255.0 ng/mL; P = .097; Cohen d = 1.03). Across groups, significant changes after the intervention were increased the IKDC score, vertical jump height, normalized quadriceps strength, quadriceps symmetry index, and knee activity self-efficacy and decreased average knee pain intensity.Conclusion:No significant differences were detected between the low- and high-intensity plyometric exercise groups. Across both groups, plyometric exercise induced positive changes in knee function, knee impairments, and psychosocial status that would support the return to sports participation after ACL reconstruction. The effect of plyometric exercise intensity on articular cartilage requires further evaluation.Registration Number:Clinicaltrials.gov NCT01851655

A circumferential hoof clamp method to induce controlled and reversible lameness in the forelimbs of eight horses was assessed. Peak vertical forces and vertical impulses were recorded using a force plate to verify induced lameness. Video recordings were used by blinded observers to determine subjective lameness using a 0-5 scale and any residual lameness following clamp loosening. Tightening of clamps resulted in consistent, visible lameness in the selected limbs in all horses. Lameness was confirmed by significant decreases from baseline in the peak vertical force (P

Summary Reasons for performing study To investigate and further characterise posture and movement characteristics during forward and backward walking in horses with shivering and acquired, bilateral stringhalt. Objectives To characterise the movement of horses with shivering (also known as shivers) in comparison with control horses and horses with acquired bilateral stringhalt. Study design Qualitative video analysis of gait in horses. Methods Owners' and authors' videos of horses with shivering or stringhalt and control horses walking forwards and backwards and manually lifting their limbs were examined subjectively to characterise hyperflexion, hyperextension and postural abnormalities of the hindlimbs. The pattern and timing of vertical displacement of a hindlimb over one stride unit was evaluated among control, shivering and stringhalt cases. Results Gait patterns of shivering cases were characterised as follows: shivering-hyperextension (-HE, n = 13), in which horses subjectively showed hyperextension when backing and lifting the limb; shivering-hyperflexion (-HF, n = 27), in which horses showed hindlimb hyperflexion and abduction during backward walking; and shivering-forward hyperflexion (-FHF, n = 4), which resembled shivering-HF but included intermittent hyperflexion and abduction with forward walking. Horses with shivering-HF, shivering-FHF and stringhalt (n = 7) had a prolonged swing phase duration compared with control horses and horses with shivering-HE during backward walking. With the swing phase of forward walking, horses with stringhalt had a rapid ascent to adducted hyperflexion of the hindlimb, compared with a rapid descent of the hindlimb after abducted hyperflexion in horses with shivering-FHF. Conclusions Shivering affects backward walking, with either HE or HF of hindlimbs, and can gradually progress to involve intermittent abducted hyperflexion during forward walking. Shivering-HF and shivering-FHF can look remarkably similar to acquired bilateral stringhalt during backward walking; however, stringhalt can be distinguished from shivering-HF by hyperflexion during forward walking and from shivering-FHF by an acute onset of a more consistent, rapidly ascending, hyperflexed, adducted hindlimb gait at a walk.

Objective—To assess effects of zoledronic acid on biomarkers, radiographic scores, and gross articular cartilage changes in dogs with induced osteoarthritis. Animals—21 purpose-bred hound-type dogs. Procedures—The left stifle joint of each dog was examined arthroscopically to determine initial articular cartilage status, which was followed by cranial cruciate ligament (CrCL) transection to induce osteoarthritis. Dogs were assigned to 3 groups (control group, low dose [10 μg of zoledronic acid/kg], or high dose [25 μg of zoledronic acid/kg). Treatments were administered SC every 3 months for 1 year beginning the day after CrCL transection. Serum and synovial fluid samples and radiographs were obtained 0, 1, 3, 6, 9, and 12 months after transection. At 12 months, each joint was scored for cartilage defects. Serum and synovial fluid biomarkers of bone and cartilage turnover (bone-specific alkaline phosphatase, type I and II collagen, carboxy-propeptide of type II collagen, and chondroitin sulfate 846) were analyzed with ELISAs. Results—The high-dose group had fewer total articular defects and lower severity scores in CrCL-transected stifle joints than did the control group. In addition, the high-dose group had significantly less change in collagenase cleavage of type I or II collagen in the synovial fluid at 1 and 3 months after CrCL transection than did the control group and also had greater changes in bone-specific alkaline phosphatase in synovial fluid at 3 months after CrCL transection than did the control group. Conclusions and Clinical Relevance—Zoledronic acid had a chondroprotective effect in dogs with a transected CrCL.

Summary Reasons for performing study Palmar osteochondral disease (POD) is an overload arthrosis that commonly affects fetlock joints of racing Thoroughbreds (TB) but the aetiopathogenesis of the disease has not been well defined. Objectives The aim of this study was to compare India ink perfusion in the dorsal and palmar condyles of the third metacarpal bone (McIII) in both passively flexed and maximally extended fetlock joints from paired equine cadaver limbs. Study design Descriptive cadaver study comparing perfusion of condyles of McIII in paired cadaver limbs in flexion (control group) and maximal extension (intervention group). Methods Pairs of forelimbs were acquired from 5 TB horses subjected to euthanasia for reasons unrelated to lameness. Limb pairs were perfused intra-arterially with India ink and then randomly assigned to passive flexion or maximal extension of the fetlock joint. Limbs were sectioned sagittally in 3 mm sections through the fetlock and 12 sections per limb processed using a modified tissue-clearing technique. Sections were subsequently digitally imaged and bone perfusion evaluated with image analysis software. Results Greater perfusion of the dorsal condyle than of palmar condyle was observed in 78% of sections from limbs in passive flexion and 92% of maximally extended sections. Perfusion to the palmar aspect of the condyle was significantly decreased (P

SummaryObjectiveDevelop a non-terminal animal model of acute joint injury that demonstrates clinical and morphological evidence of early post-traumatic osteoarthritis (PTOA).MethodsAn osteochondral (OC) fragment was created arthroscopically in one metacarpophalangeal (MCP) joint of 11 horses and the contralateral joint was sham operated. Eleven additional horses served as unoperated controls. Every 2 weeks, force plate analysis, flexion response, joint circumference, and synovial effusion scores were recorded. At weeks 0 and 16, radiographs (all horses) and arthroscopic videos (OC injured and sham joints) were graded. At week 16, synovium and cartilage biopsies were taken arthroscopically from OC injured and sham joints for histologic evaluation and the OC fragment was removed.ResultsOC fragments were successfully created and horses were free of clinical lameness after fragment removal. Forelimb gait asymmetry was observed at week 2 (P = 0.0012), while joint circumference (P

Objective—To characterize clinical findings, outcomes, muscle characteristics, and serum or muscle concentrations of α-tocopherol for horses with vitamin E–responsive signs of muscle atrophy and weakness consistent with signs of equine motor neuron disease (EMND). Design—Retrospective case-control study. Animals—8 affected (case) adult horses with acute (n = 3) or chronic (5) gross muscle atrophy that improved with vitamin E treatment and 14 clinically normal (control) adult horses with adequate (within reference range; 8) or low (6) muscle concentrations of α-tocopherol. Procedures—Medical records were reviewed, serum and muscle concentrations of α-tocopherol were measured, and frozen biopsy specimens of sacrocaudalis dorsalis medialis muscle and gluteal muscle were histologically evaluated for pathological changes. Fiber type composition and fiber diameters were assessed in gluteal muscle specimens. Results—A myopathy that was histologically characterized by redistribution of mitochondrial enzyme stain (moth-eaten appearance) and anguloid atrophy of myofibers was evident in sacrocaudalis dorsalis medialis muscle fibers of the 8 affected horses that had low serum (6/8) or skeletal muscle (5/5) concentrations of α-tocopherol; these histopathologic changes were not found in muscle specimens of control horses with low or adequate muscle concentrations of α-tocopherol. All affected horses regained strength and muscle mass within 3 months after initiation of vitamin E treatment and dietary changes. Conclusions and Clinical Relevance—A vitamin E–deficient myopathy characterized histologically by a moth-eaten appearance in the mitochondria and anguloid myofiber atrophy in frozen sections of sacrocaudalis dorsalis medialis muscle biopsy specimens was found in horses with clinical signs of EMND that were highly responsive to vitamin E treatment. This myopathy may be a specific syndrome or possibly precede the development of neurogenic muscle fiber atrophy typical of EMND.

Objective—To determine the maximum amount of flexion and extension of the carpal, tarsal, metacarpophalangeal, and metatarsophalangeal joints and the percentage duration of the stance and swing phases of the stride for horses walking on an underwater treadmill in various water depths. Animals—9 healthy adult horses. Procedures—Zinc oxide markers were placed on the forelimbs and hind limbs of the horses. Video was recorded of horses walking (0.9 m/s) on an underwater treadmill during baseline conditions (< 1 cm of water) or in various amounts of water (level of the metatarsophalangeal, tarsal, and stifle joints). Maximum amount of joint flexion and extension, range of motion (ROM), and the percentage durations of the stance and swing phases of the stride were determined with 2-D motion analysis software. Results—The ROM was greater for all evaluated joints in any amount of water versus ROM for joints in baseline conditions (primarily because of increases in amount of joint flexion). The greatest ROM for carpal joints was detected in a tarsal joint water depth, for tarsal joints in a stifle joint water depth, and for metacarpophalangeal and metatarsophalangeal joints in metatarsophalangeal and tarsal joint water depths. As water depth increased, the percentage durations of the stance and swing phases of the stride significantly decreased and increased, respectively. Conclusions and Clinical Relevance—Results of this study suggested that exercise on an underwater treadmill is useful for increasing the ROM of various joints of horses during rehabilitation and that the depth of water affects the amount of flexion and extension of joints.

Objective—To determine the effects of yearling sale purchase price, exercise history, lameness, and athletic performance (speed) on purchase price of 2-year-old in-training Thoroughbreds and to compare the distance exercised within 60 days prior to 2-year-old in-training sales between horses with high yearling sale purchase prices versus those with low yearling sale purchase prices and between horses with lameness during training and those without lameness during training. Design—Prospective study. Animals—51 Thoroughbreds. Procedures—Thoroughbreds purchased at a yearling sale were trained prior to resale at 2-year-old in-training sales. Amount of exercise and lameness status during training and speed of horses at 2-year-old in-training sales were determined. Data were analyzed via the Wilcoxon rank sum test and ANOVA. Results—Median purchase price of horses at 2-year-old in-training sales was $37,000. The 2-year-old in-training sale purchase price was associated with yearling sale purchase price and distance galloped within 60 days prior to and speed recorded at 2-year-old in-training sales. Conclusions and Clinical Relevance—Horses with high yearling sale purchase prices typically had high 2-year-old in-training sale purchase prices, had low distances galloped within 60 days prior to 2-year-old in-training sales, and were classified as fast at 2-year-old in-training sales. Lameness alone was not associated with 2-year-old in-training sales purchase price. However, lameness was associated with a low distance galloped before 2-year-old in-training sales, particularly for horses with a high yearling sale purchase price; this finding suggested that yearling sale purchase price can affect training management decisions for horses with lameness.

Summary Objective Post-traumatic knee osteoarthritis (OA) is prevalent after anterior cruciate ligament reconstruction (ACLR). Biomarkers that identify individuals likely to develop OA, especially symptomatic OA, can help target preventative and therapeutic strategies. This study examined the magnitude and change over time in urinary CTX-II (uCTX-II) concentrations shortly after ACL reconstruction, and, secondarily, the associations with knee pain and function. Design Subjects were 28 patients with ACLR and 28 age- and sex-matched controls (CNTRL). Testing was conducted at four time points spaced 4weeks apart (4, 8, 12 and 16weeks post-operative in ACLR). Measures included demographics, urine samples, Numeric Pain Rating Scale (NPRS) and International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). uCTX-II concentrations were determined with competitive enzyme-linked immunosorbent assay (ELISA). uCTX-II concentrations at each time point in ACLR were compared to the mean concentration over time in CNTRL, with and without adjustment for body mass index (BMI). Changes over time in each measure and correlations between the slopes of change were examined. Results uCTX-II concentrations were significantly higher in ACLR than CNTRL through 16 weeks post-operative when adjusted for BMI. In ACLR, uCTX-II concentrations significantly decreased over time, and the slope was associated with NPRS ( r = 0.406, P = 0.039) and IKDC-SKF ( r = −0.402, P = 0.034) slopes. Conclusion uCTX-II concentrations shortly after ACLR were elevated compared to CNTRL and declined over time. Decreasing uCTX-II concentrations were associated with decreasing knee pain and improving function. uCTX-II may have a role as a prognostic marker following ACLR and warrants further investigation.

Objective—To estimate prevalences of various presale radiographic findings and of presale arthroscopy in horses offered for sale at the 2006 Keeneland September yearling sale and to compare sales prices between yearlings with and without various presale radiographic findings or a history of arthroscopy. Animals—397 Thoroughbred yearlings. Design—Cross-sectional study. Procedures—Presale radiographs and health records were examined to estimate prevalences of various radiographic findings and presale arthroscopy. Sales price records were used to compare sales prices between yearlings with and without various presale radiographic findings or a history of arthroscopy. Results—In the forelimbs, the most common radiographic findings were vascular channels in the proximal sesamoid bones (23%), enthesophytes or osteophytes in the radiocarpal joint (22%), and osteochondritis lesions involving the sagittal ridge of the third metacarpal bone (20%). In the hind limbs, the most common radiographic findings were enthesophytes or osteophytes involving the proximal sesamoid bones (39%), abnormalities of the distodorsal aspect of the third metatarsal bone (36%), enthesophytes or osteophytes involving the distal intertarsal joint (27%), and osteochondritis lesions involving the stifle joint (8%). Thirteen percent of horses had a history of presale arthroscopy. Median sales price was significantly lower in horses with fragments of the proximal phalanx than in horses without. Median sales price was significantly higher in horses with a history of presale arthroscopy than in horses without. Conclusions and Clinical Relevance—Results revealed significant associations between a diagnosis of fragments of the proximal phalanx, presale arthroscopy, and sales price in Thoroughbred yearlings.

Objective—To investigate effects of osteochondral injury on high-mobility group box chromosomal protein 1 (HMGB-1) concentrations in synovial fluid (SF) from Thoroughbreds and to compare these results with radiographic and arthroscopic scores of severity of joint injury. Animals—40 clinically normal rested Thoroughbreds (group 1) and 45 Thoroughbreds with osteochondral injury as a result of racing. Procedures—SF was obtained from the metacarpophalangeal (MCP) joints, metatarsophalangeal (MTP) joints, middle carpal joints, and radiocarpal joints. For group 2, radiographic and arthroscopic scores were determined. Concentrations of SF HMGB-1 were determined by use of an ELISA. Results—SF HMGB-1 concentrations in osteochondral-injured MCP-MTP joints were significantly higher than in normal MCP-MTP joints. Similarly, SF HMGB-1 concentrations in osteochondral-injured carpal joints were significantly higher than in normal carpal joints. Radiographic and arthroscopic scores were not correlated with SF HMGB-1 concentrations. Synovial fluid HMGB-1 concentrations ≥ 11 ng/mL for MCP-MTP joints and ≥ 9 ng/mL for carpal joints discriminated osteochondral-injured joints from normal joints. Horses with HMGB-1 concentrations ≥ 11 ng/mL for MCP-MTP joints were twice as likely to have an osteochondral injury, and horses with HMGB-1 concentrations ≥ 9 ng/mL for carpal joints were 4 times as likely to have an osteochondral injury. Conclusions and Clinical Relevance—Osteochondral injury was associated with a significant increase in SF HMGB-1 concentrations in MCP-MTP and carpal joints, compared with results for clinically normal Thoroughbreds. Analysis of SF HMGB-1 concentrations may be useful for evaluation of joint injury in horses.

SummaryObjectivesTo investigate the effects of exercise and osteochondral (OC) injury on type II collagen degradation products (collagenase cleavage neoepitope commercially known as C2C) in synovial fluid (SF) from Thoroughbred (TB) racehorses and to compare these results with radiographic and arthroscopic scores of severity of joint injury.MethodsMetacarpophalangeal/metatarsophalangeal (MCP/MTP) and carpal SF was obtained from (1) 20 normal rested horses, (2) the same horses after 5 to 6 months of race training, and (3) 27 horses with OC injury from racing. For group 3, radiographic and arthroscopic scores were determined. Concentrations of SF C2C were determined by ELISA.ResultsSF C2C concentrations in OC injured carpal and MCP/MTP joints were significantly different than rested and exercised joints (P

Summary Objectives Validate use of a commercially available immunoassay for measurement of bone alkaline phosphatase (BAP) in equine serum and synovial fluid (SF), and investigate the effects of osteochondral (OC) injury in horses on BAP concentrations in serum and SF. Methods SF was collected from 37 joints of 34 Thoroughbred (TB) racehorses undergoing arthroscopic surgery for the removal of OC fragments from either the carpal joints ( n =18) or the metacarpo-/metatarsophalangeal (MP) joints ( n =19). SF was also obtained from 52 joints of 16 normal TB horses, collected bilaterally from carpal joints of 10 horses ( n =40), and MP joints of six horses ( n =12). Blood was obtained from all 50 horses. A commercially available immunoassay was validated and subsequently used to determine equine serum and SF BAP concentrations. Correlations to radiographic and arthroscopic scores were assessed. Results BAP concentrations were significantly lower in serum from horses with OC injury in their carpal or MP joints than in serum from normal horses. SF BAP concentrations in normal and OC injured carpal joints were significantly higher than MP joints. BAP concentrations were significantly higher in SF from OC injured carpal joints than normal. BAP concentrations were affected by joint sampled, with age having a significant interaction. Concentrations of BAP in the serum ( 22U/L) and a ratio of SF to serum ≥0.5 were predictive of OC injury. Radiographic and arthroscopic scores significantly correlated with serum BAP concentrations, and SF:serum BAP correlated with arthroscopic scores. Conclusions Determination of serum and SF BAP concentrations may be beneficial in the investigation of early joint injury. Joint and injury dependent differences in BAP concentrations allowed the estimation of predictive value for identifying OC injury.

Objective—To characterize lameness during training and compare exercise variables and financial returns among yearling Thoroughbreds that were bought for the purpose of resale for profit. Animals—40 yearling Thoroughbreds. Design—Prospective study. Procedures—Horses purchased at yearling sales (summer 2004) were trained prior to resale at 2-year-olds in training sales (spring 2005). Horses were monitored daily for diagnosis and treatment of lameness during training. Selected variables, including sex, age, purchase price, lameness, distance (No. of furlongs) galloped during training, and financial returns, were compared among horses that had performance speeds (assessed at 2-year-olds in training sales) classified as fast, average, or slow. Results—37 of 40 horses became lame during training, most commonly because of joint injury. Eighteen of the lame horses had hind limb injuries only; 5 horses had injuries in forelimbs and hind limbs. The frequency of new cases of lameness increased as the date of the 2-year-olds in training sales approached. At the sales, 4, 21, and 15 horses were classified as fast, average, or slow, respectively; median financial return was slightly (but significantly) different among horses classified as fast ($14,000), average ($0), or slow (–$8,000). Conclusions and Clinical Relevance—Incidence of lameness during training in yearling horses purchased for the purpose of resale for profit was high. Lameness more commonly affected hind limbs than forelimbs and was attributable to joint injury in most horses. Financial returns differed between horses classified as fast and average or slow at the 2-year-olds in training sales.

Summary Objectives (1) To investigate the effects of exercise and osteochondral (OC) injury on synovial fluid (SF) chondroitin sulfate (CS) and hyaluronan (HA) concentration and chain length, (2) to compare SF and cartilage CS data from joints with OC fragmentation, and (3) to compare SF CS and HA profiles with those seen in serum from the same horses. Methods Serum and SF were obtained from (1) normal horses after 8 weeks rest, (2) the same horses after 9 months treadmill training, and (3) horses with OC injury from racing. Articular cartilage was also collected from group 3 horses. Concentrations and chain lengths of CS and HA were determined by gel chromatography and fluorophore-assisted carbohydrate electrophoresis. Results SF CS peak chain length in the OC injury group increased significantly (18.7kDa) when compared to rested horses (11.6kDa), with exercise producing an intermediate chain length (15.6kDa). Cartilage and serum from the OC injury group had the abnormally long CS chains seen in SF from these horses. Total SF HA was significantly lower in the OC injury group compared to the rested group. Both the OC injury group and the exercised group had significant decreases in SF HA chain length compared to the rested group. Conclusions Chain length of SF CS was increased by exercise and OC injury. Exercise resulted in a modest increase, whereas OC injury caused a marked increase. In contrast to CS, SF HA chain length was decreased by OC injury, and to a lesser extent by exercise. Chain length analysis of SF CS and HA may provide a useful tool for evaluation of joint health.

Objective—To evaluate effects of zoledronate on markers of bone metabolism in dogs after transection of the cranial cruciate ligament (CrCL).Animals—21 adult dogs.Procedure—Unilateral CrCL transection was performed arthroscopically. Dogs were allocated to 3 groups (control group, low-dose zoledronate [10 µg/kg, SC, q 90 d for 12 months], and high-dose zoledronate [25 µg/kg, SC, q 90 d for 12 months]). Serum osteocalcin (OC), serum bone-specific alkaline phosphatase (BAP), and urine pyridinoline and deoxypyridinoline concentrations were measured at 0, 1, 3, 6, 9, and 12 months after surgery. Bone mineral density (BMD) was determined in the distal portion of the femur and proximal portion of the tibia via computed tomography at each time point. Data were analyzed by a repeated-measures ANOVA.Results—Zoledronate inhibited OC in the high-dose group at 9 and 12 months and at 12 months in the low-dose group, compared with the control group. High-dose zoledronate decreased BAP concentrations 3 and 9 months after surgery. In the control group, BMD was decreased in the femoral condyle and caudal tibial plateau. Zoledronate prevented significant BMD decreases starting 1 month after transection, compared with control dogs. In the caudomedial aspect of the tibial plateau, both zoledronate groups had significant increases in BMD after 3 months, compared with control dogs.Conclusions and Clinical Relevance—Zoledronate may reduce subchondral bone loss and effect markers of bone metabolism in dogs with experimentally induced instability of the stifle joint and subsequent development of osteoarthritis. (Am J Vet Res2005;66:1487–1495)

The first month of life is one of the most vulnerable times for any species, and foals are no exception. It is a time where foals must adjust to their environment while still somewhat compromised immunologically, and their musculoskeletal systems are rapidly growing and adjusting to the stresses applied from an increasing amount of exercise. Therefore, if a foal is born with or rapidly acquires an abnormality or disease related to the musculoskeletal system, rapid adjustments must be made to allow the foal to grow and respond so that future athletic performance will be minimally compromised. Problems must be identified early, which requires multiple thorough examinations so that appropriate steps can be taken. When problems are identified, treatment often entails a complex mixture of conservative therapy (eg, exercise adjustment), medical therapy, or surgery. This article summarizes treatment options for orthopedic disorders that tend to be present or become clinically evident within the first month of life. Those disorders that are likely present but do not manifest clinically until later in life, such as osteochondritis dissecans (OCD), will not be discussed in this chapter.

Objective—To evaluate the temporal pattern of prostaglandin (PG) E2 concentrations in synovial fluid after transection of the cranial cruciate ligament (CCL) in dogs and to correlate PGE2 concentrations with ground reaction forces and subjective clinical variables for lameness or pain. Animals—19 purpose-bred adult male Walker Hounds. Procedure—Force plate measurements, subjective clinical analysis of pain or lameness, and samples of synovial fluid were obtained before (baseline) and at various time points after arthroscopic transection of the right CCL. Concentrations of PGE2 were measured in synovial fluid samples, and the PGE2 concentrations were correlated with ground reaction forces and clinical variables. Results—The PGE2 concentration increased significantly above the baseline value throughout the entire study, peaking 14 days after transection. Peak vertical force and vertical impulse significantly decreased by day 14 after transection, followed by an increase over time without returning to baseline values. All clinical variables (eg, lameness, degree of weight bearing, joint extension, cumulative pain score, effusion score, and total protein content of synovial fluid, except for WBC count in synovial fluid) increased significantly above baseline values. Significant negative correlations were detected between PGE2 concentrations and peak vertical force (r, –0.5720) and vertical impulse (r, –0.4618), and significant positive correlations were detected between PGE2 concentrations and the subjective lameness score (r, 0.5016) and effusion score (r, 0.6817). Conclusions and Clinical Relevance—Assessment of the acute inflammatory process by measurement of PGE2 concentrations in synovial fluid may be correlated with the amount of pain or lameness in dogs. (Am J Vet Res 2004;65:1269–1275)

Objective—To determine whether stromal cell-derived factor-1 (SDF-1) concentrations in serum, plasma, and synovial fluid differed among untrained, race-trained, and osteochondral-injured Thoroughbred racehorses. Animals—22 racehorses without osteochondral injury and 37 racehorses with osteochondral injury. Procedures—Horses without osteochondral injury were examined before and after 5 to 6 months of race training. Horses with osteochondral injury were undergoing arthroscopic surgery for removal of osteochondral fragments from carpal or metacarpophalangeal or metatarsophalangeal joints (fetlock joints). Serum, plasma, and fetlock or carpal synovial fluid samples were obtained and analyzed for SDF-1 concentration by use of an ELISA. Results—In horses with fetlock or carpal joint injury, mean synovial fluid SDF-1 concentrations were significantly higher, serum SDF-1 concentrations were significantly lower, and synovial fluid-to-serum SDF-1 ratios were significantly higher than in untrained and trained horses. Synovial fluid SDF-1 concentrations were not significantly different between trained and untrained horses. Plasma SDF-1 concentrations were not different among the 3 groups. Results obtained with serum, compared with synovial fluid and plasma, had better sensitivity for differentiating between osteochondral-injured horses and uninjured horses. In horses with fetlock joint osteochondral injury, serum SDF-1 concentrations were correlated with radiographic and arthroscopic inflammation scores, but not arthroscopic cartilage scores. Conclusions and Clinical Relevance—Results suggested that serum SDF-1 concentrations were more sensitive than plasma and synovial fluid concentrations for detection of osteochondral injury in the fetlock or carpal joint of racehorses. Analysis of serum and synovial SDF-1 concentrations in horses with experimentally induced joint injury may help define the onset and progression of post-traumatic osteoarthritis and aid in the evaluation of anti-inflammatory treatments.

Objectives—To determine concentrations of matrix metalloproteinase (MMP)-2 and -9 in synovial fluid; and mRNA expression of MMP-1, -13, and -3; interleukin[ IL]-1α and β; and tumor necrosis factor(TNF)-α in synovial membrane and articular cartilage from horses with naturally occurring joint disease. Sample Population—Synovial fluid (n = 76), synovial membrane (59), and articular cartilage (45) from 5 clinically normal horses and 55 horses with joint disease categorized as traumatic (acute [AT] or chronic [CT]), osteochondritis dissecans (OCD), or septic (S). Procedure—Synovial fluid gelatinase concentrations were analyzed, using zymography. Synovial membrane and articular cartilage mRNA expression for MMP-1, -3, and -13, IL-1α and β, TNF-α, type-II collagen, and aggrecan were analyzed, using quantitative reverse transcriptase-polymerase chain reaction. Results—Synovial fluid pro-MMP-2 concentration was significantly higher in diseased joints than normal joints. Septic joints had significantly higher concentrations of pro and active MMP-9. Stromelysin-1 was expressed in ≥ 80% of synovial membrane and articular cartilage samples and was strongly influenced by age. Collagenases were rarely expressed, with MMP- 13 expressed only in diseased joints. Interleukin-1β expression was significantly higher in all OCD samples and was influenced by age. Tumor necrosis factor- α expression was significantly higher in cartilage from joints with AT and OCD. There was no correlation between MMP or cytokines and type-II collagen or aggrecan expression. Conclusions and Clinical Relevance—Matrix metalloproteinase- 2 and -3 are abundant in naturally occurring joint disease and normal joints. Interleukin-1β and TNF-α may be important in the pathogenesis of OCD. Age affects MMP and IL-1β concentrations. (Am J Vet Res 2001;62:1467–1477)

Summary Objective To determine whether dimethylmethylene blue (DMMB) analysis, when combined with agarose gel filtration chromatography (Superose 6), can be performed instead of fluorophore-assisted carbohydrate electrophoresis (FACE) to determine chondroitin sulfate (CS) chain length in synovial fluid (SF). Methods SF was obtained from (1) normal horses after 8 weeks of rest, (2) the same horses after 9 months of treadmill training, and (3) horses with osteochondral (OC) injury from racing. SF CS concentrations and chain lengths were determined by gel chromatography and DMMB analysis and compared with previous results determined by FACE analysis on the same samples. Results DMMB analysis showed that SF CS peak chain length in the OC injury group increased significantly (18.7kDa) when compared to rested and exercised normal horses (15.6kDa). The assay had a positive predictive value of 71% and a negative predictive value of 75% for discriminating between normal and injured joints. Conclusions We report a simple and inexpensive DMMB analysis of SF CS chain length, which, when coupled with Superose 6 chromatography, discriminates between normal and post-injury joints. Similar to our previous FACE analysis results [Brown MP, Trumble TN, Plaas AHK, Sandy JD, Romano M, Hernandez J, et-al. Exercise and injury increase chondroitin sulfate chain length and decrease hyaluronan chain length in synovial fluid. Osteoarthritis Cartilage 2007;15], our DMMB results show an increase in the chain length of the CS in the SF of injured joints.

Objective—To determine the effects of various presale radiographic findings for Thoroughbreds sold at a yearling sale on 2-year-old racing performance of those horses. Animals—397 Thoroughbreds. Design—Cohort study. Procedures—Thoroughbreds offered for sale at a Thoroughbred sales facility in Kentucky were selected via a randomization procedure. Effects of various presale radiographic findings on the following measures of 2-year-old racing performance were determined: having started a race and having placed (ie, finished in first, second, or third place) in a race at least once, total amount of money earned, and amount of money earned per start. Results—Of the 397 horses, 192 (48%) started in at least 1 race during the 2-year-old racing year. The odds of failure to start a race as a 2-year-old were 1.78 times as great for horses with forelimb proximal sesamoid bone osteophytes or enthesophytes as for horses without this finding (95% confidence interval, 1.01 to 3.16). The odds of failure to start a race as a 2-year-old were 2.02 times as great for horses with hind limb proximal phalanx osteochondral fragments as for horses without this finding (95% confidence interval, 0.95 to 4.31), although this result was not significant. Radiographic findings did not have an effect on total amount of money earned, amount of money earned per start, or whether horses placed in a race. Conclusions and Clinical Relevance—Presale radiographic detection of forelimb proximal sesamoid bone osteophytes or enthesophytes or hind limb proximal phalanx osteochondral fragments in yearlings were associated with failure to start a race during the 2-year-old racing year in study horses.

The aim of this study was to evaluate the effect of three footing surfaces on the flexion/extension, and range of motion (ROM) of the carpus, tarsus and fetlocks in the horse. The percentage of stride spent in the stance phase of sound horses at the walk was also measured. Nine sound horses were walked on hard ground (HD), soft ground (SF) and a land treadmill (LT), and five complete gait cycles were recorded by a digital video camera. Retro-reflective markers were placed on the skin at four anatomical locations on the left fore and hind limbs, and data were analyzed using two-dimensional (2D) motion-analysis software. Maximal flexion/extension angles and range of motion were calculated for each joint, and the percentage of the stride spent in stance phase was determined for each stride. Maximal flexion of the tarsus and hind fetlock was greater on LT and SF compared to HD, while maximal flexion of the carpus was greater on LT compared to HD and SF. Maximal extension of the carpus was greater on HD compared to SF and LT, maximal extension of the tarsus was greater on HD and SF compared to LT, and maximal extension of the forelimb and hind limb fetlocks was greater on LT compared to HD and SF. The greatest overall ROM of the carpus and fetlocks was achieved on LT, while the greatest overall ROM of the tarsus was achieved on SF. The stance percentage of the stride for the hind limb was significantly different between all surfaces. In conclusion, walking surface influences flexion/extension of the carpus, tarsus and fetlocks in healthy horses, which should be considered when walking equine rehabilitation cases.

Palmar foot pain is frequently treated by steroid injections into the distal interphalangeal joint (DIPJ) in the anticipation that the steroid will diffuse to the navicular bursa and palmar foot structures. The object of this study was to determine if triamcinolone acetonide (TA) would in fact be able to locally diffuse from the DIPJ into the navicular bursa in horses affected by palmar foot pain. Both forelimb DIPJs (nine horses) were injected with 10 mg of TA. Navicular bursa fluid samples, both forelimb and one hind limb (systemic control), were analysed for TA with high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) six hours later. Foot radiographs were graded (0-4) on severity of changes. Forelimb navicular bursa TA concentrations (mean±sd log(10), 3.20±0.56) were significantly higher than systemic control concentrations (mean±sd log(10), 1.89±0.3) (P0.0001). Horses with a radiographic grade of2 were four times as likely to have TA log(10) concentrations less than 3.2 (158.49 ng/ml). TA locally diffused from the DIPJ into the navicular bursa in horses affected by palmar foot pain; TA concentrations decreased as radiographic severity increased.

Objective—To determine the effects of horse age, osteochondral injury, and joint type on a synthesis biomarker and 3 degradative biomarkers of type II collagen in Thoroughbreds. Animals—Healthy rested adult (3- to 12-year-old) Thoroughbreds (n = 19), yearling (1- to 2-year-old) Thoroughbreds (40), and Thoroughbred racehorses (2 to 7 years old) undergoing arthroscopic surgery for removal of osteochondral fragments that resulted from training or racing (41). Procedures—Samples of blood and metacarpophalangeal, metatarsophalangeal, or carpal joint synovial fluid (SF) were collected from all horses. Commercially available assays were used to analyze SF and serum concentrations of type II collagen biomarkers of synthesis (carboxy propeptide of type II collagen [CPII]) and degradation (cross-linked C-telopeptide fragments of type II collagen [CTX II], neoepitope generated by collagenase cleavage of type I and II collagen [C1,2C], and neoepitope generated by collagenase cleavage of type II collagen [C2C]). Results—Osteochondral injury affected concentrations of CPII, CTX II, C1,2C, and C2C in SF, serum, or both, compared with concentrations in healthy adult horses. Compared with adult horses, yearling horses had increased SF or serum concentrations of degradative biomarkers (CTX II, C1,2C, and C2C). Concentrations were higher in carpal than metacarpophalangeal or metatarsophalangeal joints for all biomarkers in osteochondral-injured horses. Variable differences in SF concentrations between joint types were detected in healthy adult and yearling horses. Conclusions and Clinical Relevance—Horse age, osteochondral injury, and joint type all significantly affected type II collagen biomarker concentrations in SF and serum of Thoroughbreds.

A 364-kg (800-lb) 1-year-old mixed-breed horse was admitted for treatment of uncontrolled bleeding after castration. Multiple attempts to ligate the testicular artery through the scrotal incisions prior to referral had been unsuccessful. Because of the owner's concerns about cost, an attempt was made to control the bleeding by applying pressure to the inguinal region and administering formalin IV. However, hemorrhage continued. A decision was made to use laparoscopy to ligate the testicular artery. The horse was anesthetized and positioned in dorsal recumbency, and a routine ventral laparoscopic approach was used. The horse recovered without further complications. Laparoscopy should be considered for ligation of the testicular artery in horses with uncontrolled bleeding after castration.

In horses, lameness is often attributable to some degree of osteoarthritis (OA), a complex disease process that is highlighted by eventual degradation of articular cartilage. Conventional therapies for OA in horses are designed to relieve pain and discomfort and often include pharmacologic intervention with nonsteroidal anti-inflammatory drugs or intra-articular steroids. Oral administration of nutraceutical products to the horse is common and easy and is perceived to be a benign treatment for OA in horses. The main goal for use of nutraceuticals is to use them in OA cases to attempt to lower the dose of other drugs that are more problematic while potentially preventing further degradation (disease or structure modifying). This article attempts to define a nutraceutical, identifies areas that need to be considered when these products are used, and describes the known scientific effects of the most common compounds contained in currently available equine nutraceuticals.