Comparisons of computed tomography, contrast-enhanced computed tomography and standing low-field magnetic resonance imaging in horses with lameness localised to the foot. Part 2: Lesion identification.

REASONS FOR PERFORMING STUDY: No previous study compares computed tomography (CT), contrast-enhanced computed tomography (CECT) and standing low-field magnetic resonance imaging (LFMRI) to detect lesions in horses with lameness localised to the foot. This study will help clinicians understand the limitations of these techniques. OBJECTIVES: To determine if CT, CECT and LFMRI would identify lesions within the distal limb and document discrepancies with lesion distribution and lesion classification. METHODS: Lesions in specific structures identified on CT and MR images of feet (31 limbs) from the same horse were reviewed and compared. Distributions of lesions were compared using a Chi-squared test and techniques analysed using the paired marginal homogeneity test for concordance. RESULTS: Lesions of the deep digital flexor tendon (DDFT) were most common and CT/CECT identified more lesions than LFMRI. Deep digital flexor tendon lesions seen on LFMRI only were frequently distal to the proximal extent of the distal sesamoid and DDFT lesions seen on CT/CECT only were frequently proximal to the distal sesamoid. Lesions identified on LFMRI only were core (23.3%) or splits (43.3%), whereas lesions identified only on CT were abrasions (29.8%), core (15.8%), enlargement (15.8%) or mineralisation (12.3%). Contrast-enhanced CT improved lesion identification at the DDFT insertion compared to CT and resulted in distal sesamoidean impar ligament and collateral sesamoidean ligament vascular enhancement in 75% of cases. Low-field MRI and CT/CECT failed to identify soft tissue mineralisation and bone oedema, respectively. CONCLUSIONS AND POTENTIAL RELEVANCE: Multiple lesions are detected with CT, CECT and LFMRI but there is variability in lesion detection and classification. LFMRI centred only on the podotrochlear apparatus may fail to identify lesions of the pastern or soft tissue mineralisation. Computed tomography may fail to identify DDFT lesions distal to the proximal border of the distal sesamoid.

Comparisons of computed tomography, contrast enhanced computed tomography and standing low-field magnetic resonance imaging in horses with lameness localised to the foot. Part 1: anatomic visualisation scores.

REASONS FOR PERFORMING STUDY: To date, few reports exist comparing magnetic resonance imaging (MRI) and computed tomography (CT) for imaging of the equine distal limb, yet clinicians are required to decide which modality to use regularly. OBJECTIVES: To report and compare anatomic visualisation scores obtained for CT, contrast enhanced CT (CECT) and standing low-field MRI (LFMRI) in the equine foot. HYPOTHESIS: Anatomic visualisation score discrepancies would exist between CT, CECT and LFMRI. METHODS: Images of 22 lame horses (31 limbs) undergoing both CT and LFMRI of the foot were reviewed. When available, CECT images were reviewed. The deep digital flexor tendon (DDFT) was categorised into proximal to distal levels (A-D), structures were assigned visualisation scores (Grades 0-3) and technique comparisons were made using the paired marginal homogeneity test. RESULTS: Computed tomography and LFMRI had similar visibility scores for the navicular bone, middle phalanx, DDFT-B, collateral ligaments of the distal interphalangeal joint and collateral sesamoidean ligament of the navicular bone. The proximal and distal phalanx had lower visibility scores with LFMRI. The distal DDFT (C-D), distal sesamoidean impar ligament and synovial structures had higher scores with LFMRI. Contrast enhanced CT lowered DDFT and collateral sesamoidean ligament scores and raised distal interphalangeal synovium CT visualisation scores. CONCLUSIONS AND POTENTIAL RELEVANCE: Visualisation scores differ depending on imaging technique and anatomic structure of interest. This information increases our understanding of the limitations of CT, CECT and LFMRI to visualise anatomy in clinical cases.

Caecal intussusceptions in horses: a New Zealand perspective.

OBJECTIVE: To establish the prevalence of intussusceptions involving the caecum in a population of horses admitted to a university hospital for colic. DESIGN: Retrospective clinical study METHODS: Medical records of all horses admitted to the Massey University Veterinary Teaching Hospital between 1991 and 2004 were examined for information of those horses diagnosed with an intussusception involving the caecum. RESULTS: A total of 135 horses were admitted for colic surgery during the study period and 61 horses had a diagnosis of ileocaecal (37), caecocaecal (5) or caecocolic intussusception (19) made either at surgery or necropsy. Of the horses with ileocaecal intussusception, 32 had an incomplete hand-sewn ileocaecostomy without reduction and 29 survived to discharge. All the horses with caecocaecal intussusceptions were diagnosed preoperatively via rectal examination and/or transabdominal ultrasound: 2 were euthanased at surgery and 3 survived to discharge. In the 19 horses with caecocolic intussusceptions, manually reduction at surgery was performed in 6 and 5 of them survived to discharge. A typhlectomy was performed via a colotomy in 6 horses, 3 of which survived to discharge. CONCLUSIONS: The high prevalence of intussusceptions involving the caecum seen at this referral centre may indicate a higher prevalence in New Zealand than is reported elsewhere in the world. CLINICAL RELEVANCE: Intussusceptions involving the caecum should be considered as a differential diagnosis in horses presenting with chronic low-grade colic. Transabdominal ultrasound is useful for identifying caecocaecal and caecocolic intussusceptions. Hand-sewn side-to-side incomplete ileocaecostomy is a quick, effective and safe method of surgical treatment of ileocaecal intussusceptions.

Treatment of a metallic foreign body in the cranial cervical region of a horse.

Ingestion of foreign bodies is uncommon in horses when compared with indiscriminate grazers such as cattle. This case report describes the diagnosis and treatment of a cervical abscess in a Thoroughbred racehorse thought to be associated with ingestion of wire. Radiographic and ultrasonographic examination provided a diagnosis, and conservative treatment of the lesion with antimicrobials initially allowed the lesion to localise closer to the skin for safer surgical exploration. Intra-operative ultrasonographic imaging facilitated surgical access, removal of the foreign body, and drainage. While surgical treatment is usually necessary to resolve an abscess, initially conservative therapy may help to improve the prognosis by simplifying surgical access and reducing the risk of surgical complications.

Equine gastric ulcer syndrome in adult horses: a review.

In recent years, gastric ulceration has been recognised as a common, possibly performance-limiting disease of adult horses. Here, we aim to provide the reader with a useful review of recent literature covering all aspects of equine gastric ulcer syndrome (EGUS) in adult horses. The anatomy and physiology of the stomach, with particular reference to secretion of acid and mucosal protective mechanisms, are reviewed, as are the differing theories relating to the aetiopathogenesis of gastric ulceration. We also explore the possible influence of various management factors on development of the disease. The prevalence of the disease in racehorses has been reported to be as high as 100%. In general, horses that are in active training for racing tend to have a prevalence of around 90%, whereas pleasure horses in full work have a reported prevalence of approximately 60%. Emerging diagnostic tests which could obviate the need for gastroscopy are introduced and current recommendations for treatment are summarised, focussing on proton pump inhibitors, in particular omeprazole, administered orally. The oral administration of omeprazole has been shown to be effective in both treating horses with gastric ulceration and at preventing re-occurrence whilst the horses are in training, provided that daily dosing is maintained.

The prevalence of gastric ulceration in racehorses in New Zealand.

AIM: To establish the prevalence and factors influencing the prevalence and severity of gastric ulceration in racehorses in New Zealand. METHODS: Horses (n=171) in active training for racing by trainers (n=24) located throughout New Zealand were examined using gastroscopy during 2003 and 2004. Images of the examination were recorded and reviewed, and an ordinal grade based on the severity of gastric ulceration present was assigned, using the grading system proposed by the Equine Gastric Ulcer Council (EGUC). Information about the horses such as age, breed, sex, stabling, time at pasture, pasture quality, and presence of clinical signs consistent with equine gastric ulcer syndrome (EGUS) was recorded. RESULTS: Of the 171 horses in the study, 133 (78%) were Thoroughbreds and 38 (22%) were Standardbreds. Evidence of gastric ulceration was present in 151 (88.3%) of these. Prevalence of ulceration was higher at the lesser curvature (LC) and greater curvature (GC) of the stomach than at the saccus caecus (SC; p<0.01), and ulceration was more severe at the LC than at either the GC (p=0.02) or the SC (p<0.001). The prevalence of ulceration did not differ between the two breeds (p=0.51) or between horses of differing ages (p=0.56). Gastric ulceration was evident in 125/141 (89%) horses kept at pasture for at least 4 h/day, in all 13 (100%) horses kept at pasture full time, and in 16/17 (94%) horses stabled full time. Prevalence and severity of ulceration did not differ between horses stabled full time, kept at pasture for part of the day or kept at pasture full time (p=0.33 and 0.13, respectively), and for horses grazed on pasture severity of ulceration did not vary significantly with the quality of the pasture (p=0.12). Neither prevalence (p=0.26) nor severity (p=0.49) of gastric ulceration varied significantly with duration of training. CONCLUSIONS: The prevalence of gastric ulceration in racehorses in New Zealand is similar to that reported elsewhere for horses in active training for racing. Access to pasture for some or all of the day did not appear to be protective.

A comparison of two scoring systems for endoscopic grading of gastric ulceration in horses.

AIM: To compare two scoring systems for grading gastric ulcers in adult horses. METHODS: Digitised recordings of gastroscopy examinations of 22 horses that were part of a study on prevalence of gastric ulceration in racehorses in New Zealand were reviewed independently by three examiners. All stomachs were graded by each examiner using two different grading systems, the Equine Gastric Ulcer Council (EGUC) system and the Number/Severity (N/S) system. RESULTS: All examiners commented that the EGUC system was quicker and easier to use. There was no significant difference between examiners in the grades assigned using the EGUC system (p=0.31) and the agreement between examiners was high (Kappa values of 0. 85(1vs2), 0.88(1vs3) and 0.80(2vs3)). There was a significant difference between examiners in the grades assigned using the severity component of the N/S system (p=0.005). CONCLUSIONS: The EGUC system was more repeatable, and was faster and easier to use than the N/S system. CLINICAL RELEVANCE: The EGUC system is suitable as a standard scoring system due to its ease of use, and the repeatability and correlation of grades assigned between independent examiners. Use of a standard scoring system will more easily allow comparisons to be made between different research groups and clinicians.

Suture materials: composition and applications in veternary wound repair.

Suture materials play an important role in veterinary surgery by providing support for healing tissues during wound repair. As there is no single ideal suture material, clinicians must compromise on some properties when selecting a material for a specific purpose. By reviewing the characteristics of absorbable and non-absorbable materials, general recommendations can be made on their usage in skin, fascia, viscera and other tissues.