Analgesic and motor-blocking action of epidurally administered levobupivacaine or bupivacaine in the conscious dog

Objective  To compare the analgesic and motor-blocking effects of epidurally administered levobupivacaine and bupivacaine in the conscious dog.
Study design  Prospective, randomized, cross-over study.
Animals  Six adult female Beagle dogs.
Methods  Each animal received three doses of levobupivacaine or bupivacaine (0.5, 1.0 and 1.5 mg kg⁻¹; concentrations 0.25%, 0.50%, and 0.75%, respectively) in a total volume of 0.2 mL kg⁻¹ by means of a chronically implanted epidural catheter. Onset, duration (through pinch response in the sacral, lumbar and toe areas) and degree of analgesia and motor-blocking status was determined with a scoring system and at regular intervals over 8.5 hours before (baseline) and after drug administration.
Results  Epidurally administered levobupivacaine and bupivacaine had a similar dose-dependent analgesic action with no significant differences in onset (range: 5–8 minutes), duration (bupivacaine: 42 ± 28, 135 ± 68 and 265 ± 68 minutes, and levobupivacaine: 28 ± 33, 79 ± 55 and 292 ± 133 minutes; 0.25%, 0.50%, and 0.75%, respectively) or maximum degree of analgesia. However, levobupivacaine tended to produce a shorter duration of motor block than bupivacaine and the difference in the motor to nociceptive blockade times was significant at the highest dose.
Conclusion  Epidural levobupivacaine produced an analgesic action similar to that of bupivacaine.
Clinical relevance  Epidural levobupivacaine is suitable for clinical use in dogs, mostly at the highest dose if a high degree of analgesia is required.     

Canine platelet transfusions

Objective – To review potential platelet storage options, guidelines for administration of platelets, and adverse events associated with platelet transfusions. Data Sources – Data sources included original research publications and scientific reviews. Human Data Synthesis – Transfusion of platelet concentrates (PCs) plays a key role in the management of patients with severe thrombocytopenia. Currently PCs are stored at 22°C under continuous gentle agitation for up to 5 days. Chilling of platelets is associated with rapid clearance of transfused platelets, and galactosylation of platelets has proven unsuccessful in prolonging platelet survival. Although approved by the American Association of Blood Banks, cryopreservation of human platelets in 6% DMSO largely remains a research technique. Pre‐storage leukoreduction of PCs has reduced but not eliminated acute inflammatory transfusion reactions, with platelet inflammatory mediators contributing to such reactions. Veterinary Data Synthesis – Canine plateletpheresis allows collection of a concentrate with a high platelet yield, typically 3–4.5 × 10¹¹ versus <1 × 10¹¹ for whole blood‐derived platelets, improving the ability to provide sufficient platelets to meet the recipient's transfusion needs. Cryopreservation of canine platelets in 6% DMSO offers immediate availability of platelets, with an acceptable posttransfusion in vivo platelet recovery and half‐life of 50% and 2 days, respectively. While data on administration of rehydrated lyophilized platelets in bleeding animal models are encouraging, due to a short lifespan (min) posttransfusion, their use will be limited to control of active bleeding, without a sustained increase in platelet count. Conclusions – Fresh PC remains the product of choice for control of bleeding due to severe thrombocytopenia or thrombopathia. While cryopreservation and lyophilization of canine platelets offer the benefits of immediate availability and long‐term storage, the compromise is decreased in vivo recovery and survival of platelets and some degree of impaired function, though such products could still be life saving.     

Intracardiac foreign body in a dog

A dog that was referred to the University of Florida Veterinary Medical Center was discovered to have a bamboo skewer within the right atrium and right ventricle, traversing the tricuspid valve. The skewer was ingested approximately four months prior to referral and was partially removed via gastrotomy. The presenting complaint at the time of referral included coagulopathy, anemia and leukocytosis. A linear, hyperechoic structure was identified in the right heart during an echocardiogram. The foreign body was suspected to be a portion of the skewer that the patient had previously ingested. Cardiopulmonary bypass was performed and the foreign body was removed successfully. Complications following surgery included the development of tricuspid valve and ventricular wall thrombi, atrial flutter and amiodarone toxicity. Many indications have been described in the veterinary literature for cardiopulmonary bypass. However, to the best of the authors' knowledge, successful removal of an intracardiac foreign body with cardiopulmonary bypass has not been reported in a veterinary patient. This represents a new indication for cardiopulmonary bypass in veterinary medicine.     

Impact of injuries and disease on a cohort of two- and three-year-old thoroughbreds in training

A prospective study of injuries and disease in a cohort of Australian thoroughbreds in training was conducted with the participation of 24 trainers. From the horses catalogued at a major yearling sale in 1995, 169 were enrolled in the study and followed through their two- and three-year-old racing seasons. The principal aim was to quantify the time lost in training as a result of the various categories of injuries and disease, recorded as either days of modified training, or weeks rested at pasture. Shin soreness was the most common condition in two-year-olds (affecting 42 per cent of the horses that had entered training), followed by fetlock problems (25 per cent), and coughs and nasal discharge (16 per cent). Lameness, excluding lacerations and traumatic injuries, was the most common reason for lost training days (56.2 per cent of total days modified) and for resting horses at pasture (81.2 per cent of total weeks rested for injury or disease). Of the individual categories of injury or disease, lacerations and traumatic injuries, coughs and nasal discharge, shin soreness, carpal problems and fetlock problems were the most important causes of modified training days. In terms of weeks rested at pasture, fetlock problems, shin soreness, carpal problems, and coughs and nasal discharge had the greatest impact. Major injury was uncommon in young horses in training, but there was a high incidence of relatively low-grade injuries and disease during the training of two-year-olds.     

The synovial response to exogenous phospholipid (synovial surfactant) injected into the equine radiocarpal joint compared with that to prilocaine, hyaluronan and propylene glycol

AIMS: To determine the effects of the intra-articular injection of surface-active phospholipid in a propylene glycol carrier on synovial fluid composition and joint function of horses, and to compare these effects with those observed after the intra-articular administration of prilocaine, hyaluronan and propylene glycol alone. METHODS: Twenty-four horses were randomly allocated to four treatment groups: Group 1 100 mg of surface-active phospholipid in 1 ml of propylene glycol; Group 2 1 ml of propylene glycol; Group 3 10 ml of prilocaine; Group 4 2 ml of hyaluronan. Left radiocarpal joints were injected with the treatments and the right radiocarpal joints were injected with volume-matched saline as controls. Examinations for lameness, arthrocenteses and synovial fluid analyses were performed before and at 1, 3 and 7 days after injection. RESULTS: No horses became lame but treated joints temporarily developed mild to moderate effusions. Synovial fluid analyses indicated significantly greater inflammation in treated compared to control joints and this difference was greatest 24 hours after injection. There were no differences between the four treatments based on synovial fluid analysis except for neutrophil counts and alkaline phosphatase activities, which were significantly higher in prilocaine-treated joints. CONCLUSION: In horses, the intra-articular injection of surface-active phospholipid in a propylene glycol carrier induces clinically insignificant, temporary abnormalities in synovial fluid. Surface-active phospholipid was no more injurious to the synovium than prilocaine or hyaluronan. None of the agents used in this experiment caused lameness when injected into the joints of horses. RELEVANCE: This dose and formulation appear suitable for use in future experiments investigating the efficacy of surface-active phospholipid in the treatment or prevention of osteoarthritis in horses.     

Owner-reported equine health disorders: results of an Australia-wide postal survey

OBJECTIVE: To establish the prevalence of health disorders reported by horse owners registered with veterinary practices in Australia. DESIGN AND METHOD: Mailed questionnaire-based study of horse owners in Australia conducted in 2001. RESULTS: Data were obtained for 3901 horses belonging to 621 owners. The most prevalent health disorders were non-laminitic lameness (13.0%), skin disorders (6.1%) and behavioural disorders (4.5%). Prevalence of health disorders varied among different age, breed and sex categories within the study population, and disorders were more prevalent in male and older horses. CONCLUSION: The most frequent disorders reported by owners were lameness, skin disorders and behavioural disorders. The disease profile was similar to that described in other owner reported studies conducted in the UK and USA.     

Magnetic resonance imaging of the palmar aspect of the equine podotrochlear apparatus: normal appearance

The purpose of this study was to describe the normal magnetic resonance (MR) imaging characteristics of the palmar structures of the equine podotrochlear apparatus by means of retrospective evaluation of MR imaging studies of 16 cadaver limbs. The articular aspect of the distal sesamoid bone was not evaluated in this study. Equine digits were imaged with a human knee radiofrequency coil in a 1.5 T magnetic field, using spin echo (SE) T1-weighted, turbo spin echo proton density (TSE PD)-weighted with and without fat saturation (FS), and FS TSE T2-weighted sequences. The limbs were dissected after imaging to validate the absence of gross abnormalities of the flexor aspect of the distal sesamoid bone, of the deep digital flexor tendon, and the distal impar sesamoidean ligament. Seven deep digital flexor tendons were subjected to histologic examination to exclude any microscopic tendon pathology. The anatomic structures of the podotrochlear apparatus were easily identified on MR images. Compact bone of the flexor cortex of the distal sesamoid bone had low intensity signal on all sequences. In 11 digits an increased signal was seen within the thickness of the sagittal eminence of the flexor cortex in SE T1-weighted images and in TSE PD-weighted images without FS. Trabecular bone had a granular appearance and high signal in SE T1-weighted sequences and TSE images without FS. The deep digital flexor tendon had low signal on FS T2-weighted images, while on short echo time sequences (T1- and PD-weighted sequences), the tendon signal varied depending on the relative orientation between its fibers and the static magnetic field. Seven tendons had stippled appearance due to small intratendonous foci of slightly increased signal on transverse T1-weighted images. MR imaging provides a thorough evaluation of the anatomical structure of the podotrochlear apparatus: A good knowledge of the MR imaging appearance and anatomy and an awareness of potential pitfalls will improve diagnostic specificity for the detection of pathologic changes.