Diffusion of mepivacaine between adjacent synovial structures in the horse. Part 1: forelimb foot and carpus

This paper tests the hypothesis that the local analgesic agent mepivacaine diffuses between adjacent equine synovial structures in the forelimb and with greater frequency than latex, gelatine dye or contrast media. We report the incidence of diffusion of mepivacaine between the distal interphalangeal joint (DIPJ) and navicular bursa (NB) of the forelimbs and between the intercarpal (IC) and radiocarpal (RC) joints of 31 fresh equine cadavers. The DIPJ of one forelimb and the NB of the contra lateral forelimb and the RC joint of one forelimb and the IC joint of the contra lateral forelimb were injected with mepivacaine. After flexion and extension of the joints, synovial fluid was obtained from the synovial structures adjacent to the injected synovial structures. The concentration of mepivacaine in these samples was determined using an enzyme linked immunosorbent assay. For samples obtained by dilution of synovial fluid, the concentration of mepivacaine was determined by comparing the concentrations of urea in the diluted synovial fluid and the concentration of serum urea. Mepivacaine diffused from the DIPJ to the NB or from the NB to the DIPJ in 25/25 (100%) limbs. Mepivacaine diffused from the IC to RC joints in 24/25 (96%) limbs and from the RC to IC joints in 21/25 (84%) limbs. It was detected at concentrations >0.3 mg/l in 9/25 (36%) of IC joints after RC joint injection and in 25/25 (100%) of the NB after DIPJ injection; at concentrations >100 mg/l in 2/25 (8%) of IC and RC joints and 12/25 (48%) of NB following DIPJ injection; and at concentrations >300 mg/l in 1/25 (4%) in the IC joints following RC joint injection and in 11/25 (44%) of DIPJ following NB injection. The results show greater diffusion of mepivacaine between adjacent synovial structures than assumed from previous anatomical, latex injection and contrast arthrographic studies. This study showed that commonly performed intrasynovial analgesic techniques in the forelimb of the horse are not as specific as previously reported.     

Anatomical and functional communications between the synovial sacs of the equine stifle joint

The anatomical and functional communications of the synovial sacs of the equine stifle joint were evaluated in 50 stifle joints of 25 horses. Femoropatellar joint (FPJ) sacs were injected with 50 ml of gelatin-based dye and horses were then walked for 50 m. Horses were subsequently killed, the stifle joints dissected and the location of the dye recorded. Twenty-three horses (46 joints) had clinically normal stifle joints and in this group, anatomical communications of the stifle joints were bilaterally symmetrical in each horse. In 15 of these 23 horses (65 per cent), direct anatomical communication between the FPJ sac and the medial sac of the femorotibial joint (FTJ) was demonstrated. The FPJ sac communicated with both the medial and lateral sacs of the FTJ in four of these 23 horses (17.5 per cent). There were no anatomical communications between the FPJ sac and either sac of the FTJ in the remaining four horses (17.5 per cent). Functional communication, which was established by finding dye in the FTJ sacs were anatomical communication with the FPJ sac existed, was demonstrated in 14 of 19 horses (74 per cent). Two horses were affected with degenerative joint disease of one stifle joint. In both of these joints the FPJ sac communicated with both the medial and lateral FTJ sacs. This distribution was different from that of the contralateral joint. When performing intra-articular anaesthesia of equine stifle joints, each synovial sac needs to be injected separately to ensure that anaesthesia of the appropriate synovial sac is obtained.     

Primary synovial osteochondromatosis of the stifle in an English Mastiff

A two-year-old, 97 kg, male neutered English Mastiff was evaluated for left pelvic limb lameness of five months duration localized to the stifle joint. Following radiographic, computed tomographic and arthroscopic examination, the lameness was subsequently diagnosed as being caused by primary synovial osteochondromatosis. In total, 194 osteochondral bodies were removed using arthroscopy in combination with a mini-arthrotomy. Histology and immunohistochemistry of the loose osteochondral fragments confirmed the diagnosis with a moderately high degree of differentiation and low cellularity. Nuclear staining for Ki-67 revealed decreasing differentiation and increasing cellularity in the fragments. At the 13 months telephone follow-up the owner reported that the dog was free from lameness and had a vastly improved function compared with preoperative levels, although mild lameness did occasionally occur. This is the first report of computed tomography, arthroscopy and immunohistochemistry confirming a case of primary synovial osteochondromatosis in a dog.     

Pathology of gastritis and gastric ulceration in the horse. Part 2: A scoring system

Reasons for performing study: High numbers of racehorses in training are reported to have gastric ulceration. Gross lesion scoring systems exist, but there is no fixed protocol with which to record gastric microscopic findings. In man, the histological classification of stomach lesions helps in the identification of recognised and emerging aetiologies of gastric disease and aids accurate comparison of findings between studies. In horses, the development of such a system would therefore be of benefit. Objectives: To develop a pathological scoring system that can be applied to examine samples of the equine stomach at biopsy and post mortem. Methods and results: The equine gastritis grading (EGG) system was developed initially using horse stomachs at post mortem. The protocol involved sampling tissue from 5 fixed locations within the squamous and glandular regions. Histological examination recorded both type and degree of inflammatory infiltrate and the presence of erosions, ulceration or any other reactive change in each slide. These results were combined and an overall diagnosis of gastritis type given for each stomach. Conclusions and potential relevance: This is the first example of a complete pathological scoring system developed specifically for recording gastric lesions in the horse. It provides a thorough and repeatable method with which to examine the equine stomach in microscopic detail. It can be used in diagnostic or research situations and the consistency of the information gathered will enable accurate comparison of data between different studies. It aims to give an indication as to the currently undetermined pathological variations seen in the stomach of healthy and diseased horses, as well as increasing the understanding of the pathogenesis of gastritis and gastric ulceration. Using this information, interpretation of biopsy samples is improved.     

Plasma mepivacaine concentrations after caudal epidural and subarachnoid injection in the horse: comparative study

The venous plasma concentrations of mepivacaine were determined in 7 adult mares (420 +/- 17.1 kg) given an injection of a 2% solution of the hydrochloride at either the sacral (S2-3 to S5-C1) epidural space or the midsacral (S2-3) subarachnoid space. An average dose of 91.4 +/- 15.7 mg (4.6 +/- 0.8 ml) was needed to produce caudal epidural analgesia (CEA) and 26.7 +/- 5.4 mg (1.3 +/- 0.3 ml) to produce caudal subarachnoid analgesia (CSA). Maximal caudal analgesia extended from spinal cord segments S-1 to coccyx during CEA and CSA. The onset of analgesia as measured by response to superficial and deep muscular pinprick stimulations was significantly (P less than 0.05) faster in mares with CSA than with CEA (8.3 +/- 2.4 minutes vs 21.4 +/- 3.8 minutes). The period of analgesia was significantly (P less than 0.05) longer in mares with CEA than with CSA (80.0 +/- 11.5 minutes vs 67.4 +/- 26.3 minutes). The rate of vascular absorption of mepivacaine from the epidural space was significantly (P less than 0.05) faster than from the subarachnoid space. Maximum venous plasma concentrations of mepivacaine were similar (P greater than 0.05) after epidural and subarachnoid injections (0.05 +/- 0.03 micrograms/ml and 0.05 +/- 0.03 micrograms/ml) at the same times after mepivacaine administration (51.4 +/- 33.4 minutes and 53.6 +/- 24.3 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)     

Treatment of a ruptured medial collateral ligament of the stifle in a horse

Medial collateral ligament ruptures in horses are rare and difficult to treat. Conservative treatment usually results in degenerative joint disease that causes permanent lameness. Surgical treatment may be an alternative for salvaging horses for breeding purpose.     

1H NMR investigation of normal and osteo-arthritic synovial fluid in the horse.

Proton magnetic resonance spectroscopy (1H NMR) has been successfully used in the study of many biological fluids. The data presented here report on the metabolic profiles of normal equine synovial fluids compared with osteoarthritic (OA) fluids. Twenty-five OA synovial fluid samples and eight normal ones were collected from the forelimb fetlock joint in 22 horses, aged between five and 24 years. 1H NMR spectroscopy was carried out with a Bruker Avance DRX 500 equiped with a cryo-magnet working at 11 Tesla, and 'Mestre-C 4.9.9.6' software was used to analyze the spectra. The study assessed the increase of lactate, alanine, acetate, N-acetylglucosamine, pyruvate, citrate, creatine/creatinine, glycerol, HDL choline, and a-glucose in OA synovial fluid. The variations observed in samples from horses with OA compared to those in the control group, and similar data found in other studies, confirm that this technique may be useful in the study of joint metabolism. Its practical application may be in the evaluation of the treatment of OA in athletic horses.     

Determination of the anatomic communications among compartments within the carpus, metacarpophalangeal and metatarsophalangeal joints, stifle joint, and tarsus in llamas

OBJECTIVE: To determine the anatomic communications among compartments within the carpus, metacarpophalangeal and metatarsophalangeal joints, stifle joint, and tarsus in llamas. SAMPLE POPULATION: 88 limbs from 22 llamas necropsied because of reasons unrelated to disease of the carpus; tarsus; or metacarpophalangeal, metatarsophalangeal, or stifle joints. PROCEDURE: 1 compartment (randomly assigned) of each joint was injected with blue latex solution. Communication between joint compartments was determined by observation of latex in adjacent compartments following frozen sectioning. RESULTS: Of the 44 carpi, 30 (68%) had anatomic separation between the radiocarpal and middle carpal joints, whereas the remaining 14 (32%) had communication between the radiocarpal and middle carpal joints. In the metacarpophalangeal or metatarsophalangeal joints, medial and lateral joint compartments remained separate in 83 of 88 (94%) joints injected. The tibiotarsal and proximal intertarsal joints communicated in all tarsi examined, whereas 14 of 38 (37%) communicated between the proximal intertarsal and distal intertarsal joints. Communication between the distal intertarsal and tarsometatarsal joints was detected in 17 of 25 (68%) specimens; all 4 tarsal joints communicated in 11 of 42 (26%) specimens examined. Examination of 33 stifle joints that were successfully injected revealed communication between the femoropatellar, medial femorotibial, and lateral femorotibial joints. CONCLUSIONS AND CLINICAL RELEVANCE: These data suggest that it is important to determine the joint communications specific to each llama prior to treatment of septic arthritis. The metacarpophalangeal or metatarsophalangeal joint compartments may be considered separate, although the lateral and medial compartments infrequently communicate along the proximal palmar or plantar aspect.     

Pathological changes in the navicular bone and associated structures of the horse.

Navicular bones from 74 horses were examined at necropsy. Animals ranged in age from eight months to 30 years. Eight horses had a clinical history of navicular disease. Degenerative lesions in the fibrocartilaginous surface of the navicular bone and of the surface of the deep flexor tendons were age related changes not necessarily related to lameness. These lesions were more extensive in horses with a history of navicular disease, and were often accompanied by adhesions and subchondral cavitation of the fibrocartilaginous surface of the navicular bone. Osteophytes, present in 12 of the 74 horses, appeared to be age-related and were uncommon in horses with a history of navicular disease. Nutrient foramina on the distal border of the navicular bone were highly variable in size and shape; in horses with a history of navicular disease they often had a small external opening that became larger as it penetrated the bone. Occlusive vascular disease (arteriosclerosis) was found in sound horses and in horses with a history of navicular disease. Thrombosis of arteries or ischemic necrosis of bone was not identified in any case.