Comparison of intraosseous or intravenous infusion for delivery of amikacin sulfate to the tibiotarsal joint of horses

OBJECTIVE: To establish the route of infusion (IV or intraosseous) that results in the highest concentration of amikacin in the synovial fluid of the tibiotarsal joint and determine the duration of peak concentrations. ANIMALS: 21 horses. PROCEDURE: Regional perfusion of a limb on 15 horses was performed. Amikacin sulfate was infused into the saphenous vein or via intraosseous infusion into the distal portion of the tibia (1 g in 56 ml of lactated Ringer's solution) or proximal portion of the metatarsus (1 g of amikacin in 26 ml of lactated Ringer's solution). Amikacin concentrations were measured in sequential samples from tibiotarsal joint synovial fluid and serum. Samples were obtained immediately prior to release of the tourniquet and 0.5, 1, 4, 8, 12, and 24 hours after the tourniquet was released. Radiographic contrast material was infused into the same locations as the antibiotic perfusate to evaluate distribution in 6 other horses. RESULTS: Infusion into the saphenous vein produced the highest concentration of amikacin in the tibiotarsal joint, compared with the distal portion of the tibia (mean +/- SE, 701.8 +/- 366.8 vs 203.8 +/- 64.5 microg/ml, respectively). Use of a lower volume of diluent in the proximal portion of the metatarsus produced a peak value of 72.2 +/- 23.4 microg/ml. CONCLUSIONS AND CLINICAL RELEVANCE: For regional perfusion of the tarsus, IV infusion is preferred to intraosseous infusion, because higher concentrations are achieved in the synovial fluid, and the procedure is easier to perform.     

Iontophoresis of dexamethosone-phosphate into the equine tibiotarsal joint

In human rehabilitation medicine, dexamethasone-phosphate is theoretically iontophoresed to localized subcutaneous tissue where conversion to dexamethasone occurs. This delivery system has recently been introduced into veterinary medicine for the same purpose. However, the pharmacokinetic justification for parenteral delivery of this prodrug remains undocumented. Utilizing iontophoretic methods that are relevant to both human and veterinary clinical practice, the present investigation compared injection and iontophoresis of dexamethasone-phosphate into the equine tibiotarsal joint, also known as the tarsocrual joint. The tibiotarsal joints of seven horses were injected with 4 mL of 6 mg/mL dexamethasone-phosphate. With a similar drug concentration and over the same application site, six different horses underwent simultaneous cathodic iontophoresis (4 mA, 40 min) or passive application (0 mA, 40 min) on contralateral limbs. Following all applications, tibiotarsal joint synovium was collected. Local venous blood samples were also collected from the iontophoretic and passive application sites for analysis of plasma drug concentrations. Because of the potential for conversion of dexamethasone-phosphate to dexamethasone, an extraction and analysis protocol was developed for both chemicals. The technique demonstrated a linear range of detection (0.39-12 microg/mL) and a capability for measuring both chemicals in plasma and synovium. Conversion of dexamethasone-phosphate to dexamethasone occurred during synovial incubation (37 degrees C) and following freeze-thaw cycles. In contrast to the measurable synovial concentrations of dexamethasone-phosphate (2.3 +/- 0.96 mg/mL) and dexamethasone (0.27 +/- 0.07 mg/mL) following injection, neither drug was detected in the synovium or the local venous blood following iontophoretic or passive applications. In conclusion, these results do not confirm iontophoretic or passive delivery of measurable dexamethasone-phosphate into the tibiotarsal joint using current clinical methods.     

Management and complications associated with treatment of cervical oesophageal perforations in horses

Six horses were evaluated for colic and anorexia, choke or suspected oesophageal rupture with and without tracheal laceration. Clinical findings were variable, but a painful ventral neck swelling was noted in all cases. Two of the horses had signs of dehydration and sepsis. Additional findings included evidence of previous trauma over the trachea and oesophagus, ventral neck abscessation, choke and aspiration pneumonia. A diagnosis of oesophageal perforation was made using endoscopy. Two horses were subjected to euthanasia without treatment. All horses where treatment was attempted received debridement of the oesophageal perforation and surrounding tissues with or without surgical closure of the oesophageal defect. Other therapies included broad spectrum antimicrobials, anti‐inflammatory drugs, fluid and nutritional support as well as additional therapeutics for sepsis and individual complications. Complications included diverticulum formation, thrombophlebitis, diarrhoea, laryngeal hemiplegia, azotaemia, aspiration pneumonia, oesophageal obstruction, weight loss and laminitis. All 4 treated horses recovered from the oesophageal perforation and are able to eat a normal diet. Two of the 4 horses have had infrequent episodes of recurrent choke. Oesophageal rupture should be considered as a differential diagnosis for horses with a painful swelling of the ventral neck. With surgical debridement and adequate supportive care, oesophageal perforation cases can have a fair to good long‐term survival, although chronic complications can occur, therapy is prolonged, and a significant economic commitment is required.     

Results of conservative treatment of osteochondrosis of the tibiotarsal joint in the horse

The present study relates to 146 horses (Warmbloods and Standardbreds) exhibiting tibiotarsal joint distension and radiographic signs of OCD. Conservative treatment included normal box rest or a less intense training program together with a low energy diet. Follow-up time ranged from 6 months to 5 years and was acquired from a question-naire addressed to the owners. Localization of the lesion in the joint did not seem to play an important part in the clinical symptoms. A final evaluation was achieved in 96 horses. Sixty percent of the Warmbloods and 18% of the Standardbreds performed normally. Eighteen percent of the Standardbreds performed beyond level as opposed to 10% of the Warmbloods. Forty-one percent of the Standardbreds and 7% of the Warmbloods (66% with additional femoral ridge involvement) performed badly. Finally, 23% of the Standardbreds and 23% of the Warmbloods could not perform because problems (not related to the OCD of the tibiotarsal joint) developed during the follow-up period. If the performance problems which were not related to OCD of the tibiotarsal joint were excluded, good results were obtained in 80% of the Warmbloods, compared to only 23% of the Standardbreds. Therefore, systemic arthroscopic treatment of tarsal OCD is questionable in Warmbloods, in contrast with Standardbreds.     

Pain associated with the sacroiliac joint region: a clinical study of 74 horses

REASONS FOR PERFORMING STUDY: There has been no large study of horses with suspected sacroiliac (SI) joint region pain in which the clinical diagnosis has been supported by either abnormal radiopharmaceutical activity in the SI joint region or by periarticular infiltration of local anaesthetic solution. OBJECTIVES: To describe the clinical features of horses with SI joint region pain, to document the age, breed, sex, discipline, size and conformation of affected horses and to compare these with the author's (SD) normal case population and to document the results of infiltration of local anaesthetic solution around the SI joint region. METHODS: Horses were selected for inclusion in the study based upon the exclusion of other causes of lameness or poor performance, together with clinical signs suggestive of SI joint pain and abnormal radiopharmaceutical activity in the SI joint region and/or a positive response to periarticular infiltration of local anaesthetic solution. RESULTS: Sacroiliac joint region disease was identified in 74 horses between November 1997 and March 2002. Dressage and showjumping horses appeared to be at particular risk (P < 0.001). Affected horses were generally slightly older than the normal clinic population (P < 0.0001), taller at the withers (P < 0.0001) and of greater bodyweight (P < 0.01). There was a significant effect of breed (P < 0.001), with a substantially higher proportion of Warmblood horses (51%) in the SI pain group compared to the normal clinic population (29%). There was no correlation between conformation and the presence of SI joint region pain. The tubera sacrale appeared grossly symmetrical in most (95%) horses. Poor development of the epaxial muscles in the thoracolumbar region and asymmetry of the hindquarter musculature were common. Twenty-six horses (35%) showed restricted flexibility of the thoracolumbar region and 10 (16%) had an exaggerated response to pressure applied over the tubera sacrale. Fourteen horses (19%) were reluctant to stand on one hindlimb for prolonged periods. The majority of horses (75%) had a straight hindlimb flight and only 18% moved closely behind or plaited. In all horses restricted hindlimb impulsion was the predominant feature; invariably this was most obvious when the horse was ridden. Stiffness, unwillingness to work on the bit and poor quality canter were common. Sacroiliac joint region pain was seen alone (47%), or in conjunction with thoracolumbar pain (16%), hindlimb lameness (20%), forelimb lameness (7%) or a combination of problems (10%). Seventy-three horses (99%) had abnormalities of the SI joint region identified using nuclear scintigraphy. Infiltration of local anaesthetic solution around the SI joint region produced profound improvement in gait in all 34 horses in which it was performed. CONCLUSIONS AND POTENTIAL RELEVANCE: Careful clinical examination combined with scintigraphic evaluation of the SI joint region and local analgesia can enable a more definitive diagnosis of SI joint region pain than has previously been possible.     

Comparison of post-operative inflammatory response in horses undergoing elective castration treated preoperatively with ceftiofur crystalline free acid or procaine penicillin G

Castration is among the most common surgical procedures performed in the horse (Equus Caballus) and a variety of post-operative complications can occur. This study aims to determine if a single dose of long-acting ceftiofur crystalline free acid (CCFA) used as a preoperative antimicrobial in equine field castrations offers any reduction in post-operative inflammatory markers when compared to procaine penicillin G (PPG). Sixty-five horses aged 8 months to 2 years were randomly assigned to the CCFA (n = 33) or PPG (n = 32) treatment groups. Horses were castrated under general anaesthesia using a closed castration technique with removal of the median raphe. Quantitative and qualitative inflammatory markers were measured and short-term complications were recorded post-operatively on Days 3, 8 and 14. No clinically significant difference in any post-operative inflammatory markers between the CCFA and PPG group was detected. In the CCFA group, 48% of horses experienced short-term post-operative complications compared to 31% in the PPG group. Regardless of the preoperative treatment, castration induced significant elevation in serum amyloid A (P<0.0001), preputial oedema (P<0.0001) and scrotal oedema (P<0.0001) at Day 3. These values returned to baseline levels by Day 8. Horses with grade 3 or above preputial oedema had elevated serum amyloid A values (P<0.001). The data from this study indicate CCFA used as a preoperative antibiotic for routine castration offers no advantages over PPG. The difference in complication rate between groups is likely of minimal clinical importance, as all complications were mild and self-limiting.     

Stabling is associated with airway inflammation in young Arabian horses

We examined the effect of stabling on upper and lower airway inflammation in 14 yearling Arabian horses that had been at pasture since birth. Horses were divided into 2 groups of 7. One group was stabled for 3 months and the other remained at pasture. The groups were then switched over for another 3 months. The nasopharynx, guttural pouches and trachea were examined endoscopically and bronchoalveolar lavage performed every month. An upper airway inflammation score was devised based on the magnitude of pharyngeal lymphoid hyperplasia and guttural pouch inflammation. During stabling this score remained constant, whereas it decreased during the 3 months at pasture. Stabling was also associated with a higher number and percentage of neutrophils in bronchoalveolar lavage fluid and with a smaller percentage of lymphocytes. There was no correlation between upper airway inflammation score and bronchoalveolar lavage cytology. During a nasal occlusion test, dorsal displacement of the soft palate occurred more times in stabled than in pastured horses, but this was heavily biased by the results from one animal. We conclude that stabling is associated with inflammation of both the upper and lower airway of young horses.     

Evaluation of the rate of development of septic arthritis after elective arthroscopy in horses: 7 cases (1994-2003)

OBJECTIVE: To determine the rate of development of septic arthritis after elective arthroscopy and evaluate associations between various factors and development of this complication in horses. DESIGN: Retrospective case series. ANIMALS: 682 horses that underwent arthroscopic procedures at the University of Illinois Veterinary Teaching Hospital from 1994 to 2003. PROCEDURES: Information pertaining to signalment, joints treated, whether antimicrobials were administered, and development of postoperative septic arthritis was collected from medical records. Horses with a primary problem of septic arthritis or wounds involving joints were excluded. The following factors were evaluated to determine their roles in joint sepsis: breed, sex, joint, and preoperative and intra-articular administration of antimicrobials. Telephone interviews with clients were used to determine whether unreported septic arthritis had developed. RESULTS: 8 of 932 (0.9%) joints in 7 of 682 (1.0%) horses that underwent arthroscopy developed postoperative septic arthritis. Follow-up information after discharge from the hospital was available for 461 of the 682 horses, and of those, 8 of 627 (1.3%) joints in 7 of 461 (1.5%) horses developed septic arthritis. Breed and joint treated were significant risk factors for development of postoperative septic arthritis, with draft breeds and tibiotarsal joints more likely than others to be affected. Sex, preoperatively administered antimicrobials, and intra-articularly administered antimicrobials were not associated with development of postoperative septic arthritis. CONCLUSIONS AND CLINICAL RELEVANCE: Results can be used for comparison with data from other institutions and surgical facilities. Additional precautions should be undertaken when arthroscopic surgery involves draft breeds and tibiotarsal joints.     

Preliminary evaluation of a behaviour-based system for assessment of post-operative pain in horses following arthroscopic surgery

Objective To develop a method for objective assessment of equine post‐operative pain. Study design Prospective nonblinded clinical study. Animals Twelve adult horses: Group 1 (G1, n = 6), admitted for arthroscopy (under general anaesthesia, with multimodal analgesia); Group 2 (G2, n = 6), ‘pain free’ controls. Materials and methods Horses were filmed continuously (CVI, time‐lapse video recorder) over 72 hours, from 24 hours pre‐surgery (PS) to 48 hours post‐recovery (PR) (G1), and over 24 hours (G2). Activity budgets were determined from 24 to 0 hours PS, 0–24 and 24–48 hours PR (G1) and for 24 hours (G2). Using direct observation (DO), active behaviours and postures were recorded at set time points PS and PR (G1) and at two time points (morning/evening) (G2). Heart rate (HR) and respiration rate (RR) were recorded simultaneously. Statistical analysis investigated within‐group and between‐group time‐related changes in behaviour, HR and RR. Results There was no difference in HR or RR between G1 and G2 at any time point. Anaesthetic ‘hangover’ and hunger‐related activity modulated behaviour from 0 to 6 hours PR, when abnormal postures and locomotion occurred in all G1 horses, but no G2 horses. Compared with G1 (0–24 hours PR), G2 spent more time eating (t = ?3.34, p < 0.01), more time at the front of the stable (t = ?2.42, p < 0.05), and less time exhibiting ‘abnormal’ behaviour (U = 56, p < 0.01). Comparing PS and PR behaviour, G1 spent less time exploring from 24 to 48 hours PR (t = 3.49, p < 0.05), less time in sternal recumbency (t = ?3.8, p < 0.05) and less time moving (t = 3.19, p < 0.05). Horses tended (p < 0.07) to spend less time positioned in the front of the stable PR (less from 24 to 48 hours PR than from 0 to 24 hours PR). Comparing PR (evening) behaviour, G2 spent more time with head above withers (U = 21.5, p < 0.01), and ears forwards (U = 22, p < 0.01). G1 showed time‐related changes (all p < 0.05) in time with lower lip tense (S = 15.8), eating (S = 17.08) and with head positioned above withers (S = 18.04). No differences in event behaviours were observed between G1 and G2. Within G1, only olfactory behaviour varied significantly with time (S = 14.52, p < 0.05). Conclusions Changes in equine behaviour suggestive of post‐operative discomfort were identified using both DO and CVI. Analysis of activity budgets may be a more sensitive method of identifying behavioural changes indicative of equine discomfort than repeated DO of specific events and postures.     

Vestibular syndrome associated with temporohyoid joint fusion and temporal bone fracture in three horses

Acute onset of vestibulocochlear and facial nerve dysfunction due to a stress fracture of the petrous part of the temporal bone was diagnosed in 3 horses. The fracture was secondary to chronic inflammatory changes in the petrous part of the temporal bone and the proximal stylohyoid bone, with fusion of the temporohyoid joint. Bacterial meningoencephalitis was a complicating factor. Treatment resulted in reduction of severity of clinical signs in 2 of the 3 cases, but residual compensated vestibular deficits persisted.     

Gas arthroscopy for removal of osteochondral fragments of the palmar/plantar aspect of the metacarpo/metatarsophalangeal joint in horses

Objective— To evaluate the use of carbon dioxide (CO₂) gas for joint distention during arthroscopy for removal of osteochondral (OC) fragments of the palmar/plantar aspect of the metacarpo (MCP)/metatarsophalangeal (MTP) joints in horses.
Study Design— Clinical study.
Animals— Horses (26) with OC fragment(s) of palmar/plantar aspect of 1 or 2 MCP/MTP joint(s).
Methods— OC fragments were removed using arthroscopic technique. Joint distention was maintained by isotonic Ringer's acetate at the beginning and at the end of the procedure but during fragment removal, CO₂ was used for joint distention. After surgery, fragment removal was confirmed by radiography. Horses were discharged the day after surgery, and outcome was determined by telephone contact 3–24 months later.
Results— CO₂ joint distention resulted in a sharp image without villi obscuring the operative field. Fragments were identified and completely removed in all horses except one where a 1 mm × 3 mm radiodense body was seen on postoperative radiographs. In 5 horses, bleeding from the arthroscopic or instrument portal precluded optimal visualization when the joint was distended by gas; however, repeatedly rinsing the tip of the arthroscope with Ringer's acetate solution delivered from the fluid ingress line easily restored joint visualization. No specific complications were observed postoperatively.
Conclusions— Joint distention by CO₂ permitted optimal visualization of the palmar/plantar aspect of the MCP/MTP joints, which facilitated fragment removal.
Clinical Relevance— Gas arthroscopy is a useful technique for removal of OC fragments of the palmar/plantar aspect of the MCP/MTP joints in horses.