Quantitative Evaluation of Equine Deep Digital Flexor Tendon Morphology using Magnetic Resonance Imaging

Injury of the distal aspect of the deep digital flexor tendon (DDFT) is a recognized cause of lameness, but diagnosis is difficult. This study aimed to improve understanding of DDFT morphology and pathology using retrospective evaluation of magnetic resonance (MR) images. We hypothesized that: (1) The distal aspect of the DDFT in normal horses would have a repeatable proximal/distal pattern and symmetry between limbs and between lobes; (2) DDFT dimensions would be related to bodyweight, navicular bone dimensions and hoof size; (3) this symmetry and pattern would be lost in DDFT injury; and (4) DDFT size would increase with injury. MR images of 64 live horse limbs, 26 with no identified DDFT lesion and 38 with identified DDFT abnormalities, and 19 normal cadaver limbs were analyzed. Using standardized transverse images, measurements of DDFT cross-sectional area, medial-lateral (ML) width and dorsal-palmar depth were obtained at six preselected sites. A uniform distal to proximal shape pattern was identified in all horses. The flattened crescent shape at the insertion changed to a deeper bilobed shape more proximally, with the mid-navicular area having the greatest cross-sectional area. Strong ML (P < 0.0006) and left/right symmetry (P < 0.02) were observed. In addition, there was a strong association between DDFT cross-sectional area and horse weight (P = 0.005) and between DDFT and navicular bone ML width (P = 0.004). Symmetry between sides or between lobes was lost at sites with a unilateral lesion and correlation between horse weight and DDFT cross-sectional area was lost in the presence of lesions. DDFTs with core lesions had a consistent increase in cross-sectional area overall, but other lesion types had no significant increase in size. The shape and symmetry seen in normal tendons could be related to the mechanical demands placed upon individual lobes. The limited increase in cross-sectional area with injury may be explained by the restrictive structures of the hoof, possibly explaining the ongoing pain seen in such lesions.     

Analgesia and chemical restraint for the emergent patient.

This article discusses analgesia and chemical restraint for the emergency patient. As illness or injury affect all organ systems, specific recommendations and considerations of analgesic, anesthetic, and restraining regimens are presented. As animals of all ages, from neonates to geriatric and those that are pregnant or lactating,may require management of their illness or injury, recommendations for these patients are also presented.     

Subjective and quantitative scintigraphic assessment of the equine foot and its relationship with foot pain

It was hypothesised that in solar bone images of the front feet of clinically normal horses, or horses with lameness unrelated to the front feet, there would be less than a 10% difference in the ratio of uptake of radiopharmaceutical in either the region of the navicular bone, or the region of insertion of the deep digital flexor tendon (DDFT), compared to the peripheral regions of the distal phalanx. Nuclear scintigraphic examination of the front feet of 15 Grand Prix show jumping horses, all of which were free from detectable lameness, was performed using dorsal, lateral and solar images. The results were compared with the examinations of 53 horses with primary foot pain, 21 with foot pain accompanying another more severe cause of lameness and 49 with lameness or poor performance unrelated to foot pain. None of the horses with foot pain had radiological changes compatible with navicular disease. All the images were evaluated subjectively. The solar views were assessed quantitatively using regions of interest around the navicular bone, the region of insertion of the deep digital flexor tendon and the toe, medial and lateral aspects of the distal phalanx. In 97% of the feet of normal showjumpers, there was <10% variance of uptake of the radiopharmaceutical in the navicular bone, the region of insertion of the DDFT and the peripheral regions of the distal phalanx. There was a significant difference in uptake of radiopharmaceutical in the region of the navicular bone in horses with foot pain compared to normal horses. There was a large incidence of false positive results related to the region of insertion of the DDFT. Lateral pool phase images appeared more sensitive in identifying potentially important DDFT lesions. There was a good correlation between a positive response to intra-articular analgesia of the distal interphalangeal joint and intrathecal analgesia of the navicular bursa and increased uptake of radiopharmaceutical in the region of the navicular bone in the horses with primary foot pain. It is concluded that quantitative scintigraphic assessment of bone phase images of the foot, in combination with local analgesic techniques, can be helpful in the identification of the potential source of pain causing lameness related to the foot, but false positive results can occur, especially in horses with low heel conformation.     

Normal ultrasonographic anatomy and injury of the patellar ligaments in the horse

The purposes of this study were to investigate the ultrasonographic appearance of the patellar ligaments in clinically normal horses and to describe the clincical features, diagnosis and outcome of patellar ligament injury. The medial, middle and lateral patellar ligaments of 5 Thoroughbred and 5 Warmblood horses, free from lameness and in full work, were examined ultrasonographically. The ligaments were all of uniform echogenicity and each ligament was fairly consistent in its shape. The size of the ligaments of the Warmblood horses tended to be bigger than the lighter bodyweight Thoroughbred horses. The bone surfaces were smooth at the ligament insertions on the patella and tibia. Nine horses, including 7 showjumpers, were identified with a unilateral hindlimb lameness associated with ultrasonographic evidence of damage to one or more patellar ligaments. Four horses had primary desmitis of the middle patellar ligament, one of which had concurrent intermittent upward fixation of the patella and a second had abnormal movement of the patella. Two additional horses had desmitis of the middle patellar ligament associated with previous medial patellar desmotomy. Two horses had desmitis of both the middle and lateral patellar ligaments, and one horse had desmitis of the lateral patellar ligament alone. None of the 9 horses were able to return consistently to their former level of competition. Careful clinical evaluation and ultrasonographic examination of the patellar ligaments should be considered in horses with hindlimb lameness of otherwise undetermined cause.     

End tidal halothane concentration and postoperative analgesia requirements in dogs: a comparison between intravenous oxymorphone and epidural bupivacaine alone and in combination with oxymorphone.

The purpose of this study was to compare the effects of epidural bupivacaine (BUP) and oxymorphone/bupivacaine (O/B) and intravenous (i.v.) oxymorphone (IVO) on halothane requirements during hind end surgery and postoperative analgesia in 24 dogs. Dogs were randomly assigned to treatment groups: O/B--oxymorphone (0.1 mg/kg) in 0.75% bupivacaine (1 mg/kg for a total volume of 0.2 ml/kg); BUP--0.5% bupivacaine (1 mg/kg for a total volume of 0.2 ml/kg) with i.v. oxymorphone (0.05 mg/kg) postoperatively; and IVO--oxymorphone (0.05 mg/kg) pre- and postoperatively. Heart rate (HR), respiratory rate, arterial blood pressure, end-tidal carbon dioxide and halothane, and arterial blood gases were recorded prior to treatment and every 15 minutes thereafter. Once surgery had begun, end-tidal halothane concentrations were decreased as low as possible while still maintaining a stable anesthetic plane. Data were analyzed using ANOVA with P < 0.05 considered significant. End-tidal halothane requirements did not differ significantly among treatments. Respiratory depression was increased and HR was decreased in the O/B and IVO groups. Postoperative analgesic requirements were significantly less in dogs receiving O/B.     

Proximal suspensory desmitis: clinical, ultrasonographic and radiographic features

Clinical, ultrasonographic and radiographic features of proximal suspensory desmitis in the forelimb and the hindlimb are described. Acute cases may present with slight, localised, oedematous swelling, heat, distension of the medial palmar (plantar) vein and/or pain, whereas chronic cases or those rested immediately after onset of lameness usually have no detectable clinical signs suggestive of the source of pain. In these cases local analgesia is required to identify pain in the proximal metacarpal (metatarsal) region. Transverse ultrasonographic images of the suspensory ligament usually yield the most information and a variety of abnormalities of the proximal suspensory ligament have been identified including i) enlargement ii) poor definition of one or more of the margins of the suspensory ligament, especially dorsally iii) a well circumscribed, central hypoechoic area iv) one or more poorly defined hypoechoic areas, central or more peripheral v) a larger area of diffuse decrease in echogenicity (such lesions were seen most commonly in the hindlimb and appeared to warrant a more guarded prognosis than focal lesions). Radiographic abnormalities were identified in hindlimbs more often than in forelimbs and were usually seen in a dorsopalmar (dorsoplantar) view, and/or a lateromedial projection. Radiographic abnormalities included sclerosis of the trabeculae, a change in orientation of the trabeculae and entheseophyte formation. The most extensive radiographic abnormalities were seen together with an ultrasonographic type v lesion. The prognosis for return to full athletic function and sustained future soundness was better for forelimbs than hindlimbs, especially if the lesion, identified ultrasonographically, resolved.     

Scapulohumeral osteoarthritis in 20 Shetland ponies, miniature horses and falabella ponies

This paper describes the clinical and diagnostic features of 20 cases of scapulohumeral osteoarthritis in Shetland ponies, miniature horses and falabella ponies. The history and clinical signs were similar in all the cases Radiographically they all had consistent changes which consisted predominantly of articular osteophytes and periarticular enthesiophytes. Six of the cases had radiographic evidence of dysplasia of the scapulohumeral joint, although it was uncertain whether this was a primary or a secondary finding. No specific treatment appeared to be advantageous. At follow up, six of the ponies had to be euthanased owing to continuing severe lameness; the other 14 ponies remained lame, but were maintained at pasture by the occasional use of oral non-steroidal anti-inflammatory drugs. No definitive aetiology for the condition was identified, but it is proposed that an underlying dysplasia, or lack of collateral support may predispose the scapulohumeral joint of miniature horse breeds to the disease.