Outcome of medical treatment for horses with foot pain: 56 cases

Reasons for performing study: Currently, there are limited data regarding the long‐term outcome of horses with foot pain treated with corrective shoeing, rest and rehabilitation, and intrasynovial anti‐inflammatory medication to target lesions detected with MRI. Objective: To report the long‐term (≥12 months) outcome of horses with foot lesions following medical therapy. Hypotheses: 1) There is no association between clinical parameters considered and a poor response to therapy. 2) Horses with a deep digital flexor tendinopathy are less likely to respond to medical therapy than horses without a deep digital flexor tendinopathy. Methods: The medical records of horses with foot pain subjected to MRI examination and medical therapy (2005–2007) were evaluated retrospectively. Data collected included history, signalment, occupation, duration and severity of lameness at the time of MRI, radiological and MRI abnormalities. Number of treatments, complications and long‐term response to treatment were obtained by detailed telephone questionnaires. Association between clinical and MRI findings and long‐term lameness were investigated. Results: Frequent abnormal structures included the navicular bone, the deep digital flexor tendon, the navicular bursa and the distal interphalangeal joint. Thirty‐four of 56 horses (60.7%) failed to return to previous level of exercise due to persistent or recurrent lameness or owners' decision to decrease the horse's athletic level; however, 11 horses (32.3%) were being used for light riding. Prognosis for horses with concurrent deep digital flexor tendon, navicular bone and navicular bursa lesions was worse than horses with individual lesions. Deep digital flexor tendinopathy was strongly associated with persistent or recurrent lameness. Conclusions: Horses with multiple foot lesions managed with conservative therapy have a guarded prognosis for long‐term soundness. Deep digital flexor tendinopathies negatively influence prognosis.     

Endoscopic evaluation of the navicular bursa: observations, treatment and outcome in 92 cases with identified pathology

Reasons for performing study: Diagnostic navicular bursoscopy has been described in limited cases. Review of greater numbers is needed to define its contribution to case management and prognostic values. Objectives: To report: 1) clinical, diagnostic and endoscopic findings in a series of cases, 2) surgical techniques and case outcomes and 3) prognostic values. The authors hypothesise: 1) lameness localising to the navicular bursa is commonly associated with dorsal border deep digital flexor tendon (DDFT) lesions, 2) endoscopy allows extent of injuries to be assessed and treated, 3) case outcome relates to severity of DDFT injury and 4) the technique is safe and associated with little morbidity. Materials and methods: All horses that underwent endoscopy of a forelimb navicular bursa for investigation of lameness were identified. Case files were reviewed and those with injuries within the bursa selected for further analysis. Results: One‐hundred‐and‐fourteen horses were identified. Ninety‐two had injuries within the bursa and DDFT injuries were identified in 98% of bursae. Of those examined with magnetic resonance imaging (MRI), 56% had combination injuries involving the DDFT and navicular bone. Sixty‐one percent of horses returned to work sound, 42% returned to previous performance. Horses with extensive tearing and combination injuries of the DDFT and navicular bone identified with MRI, had worse outcomes. Conclusions: Lameness localising to the navicular bursa is commonly associated with injuries to the dorsal border of the DDFT. Endoscopy permits identification and characterisation of injuries within the navicular bursa and enables lesion management. Outcome following debridement is related to severity of injury but overall is reasonable. Potential relevance: Horses with lameness localising to the navicular bursa may have tears of the DDFT. Bursoscopy is able to contribute diagnostic and prognostic information and debridement of lesions improves outcome compared to cases managed conservatively.     

High-field magnetic resonance imaging investigation of distal border fragments of the navicular bone in horses with foot pain

Reasons for performing study: Distal border fragments of the navicular bone can be seen in lame and nonlame horses and their clinical significance remains open to debate. Objectives: To describe the magnetic resonance imaging (MRI) appearance of distal border fragments and the adjacent navicular bone. To investigate the relationship between fragments and other abnormalities of the navicular bone and the distal sesamoidean impar ligament (DSIL). Methods: Horses were included if pain causing forelimb lameness was localised to the foot and high‐field MR images were acquired. The size and location of distal border fragments were recorded. Abnormalities in the adjacent navicular bone were graded to obtain a fragment grade. A total navicular bone grade was assigned. The DSIL was also graded. A Chi‐squared test was used to test for associations between the presence of a fragment and specific lesions involving the distal border of the navicular bone, the total grade of the navicular bone, and the grade of the DSIL. Results: 427 horses were included and 111 fragments observed. There was a significant association between the presence of a fragment and the total navicular bone grade, osseous cyst‐like lesions, increased number and size of the synovial invaginations of the distal border, increased signal intensity on fat suppressed images and size of distal border entheseophytes. Conclusions: There is an association between distal border fragments and other pathological MRI abnormalities of the navicular bone. Potential relevance: Distal border fragments are part of navicular disease, but their contribution to pain and lameness remains to be clarified.     

Comparison between magnetic resonance imaging and histological findings in the navicular bone of horses with foot pain

Reasons for performing study: There is limited knowledge about both histological features in early navicular disease and what histological features are represented by increased signal intensity in fat‐suppressed magnetic resonance (MR) images of the navicular bone. Objective: To characterise increased signal intensity in the spongiosa of the navicular bone in fat‐suppressed MR images and to compare this with histopathology; and to compare objective grading of all aspects of the navicular bone on MR images with histological findings. Methods: One or both front feet of 22 horses with foot pain and a median lameness duration of 3 months were examined using high‐field MR imaging (MRI) and histopathology. The dorsal, palmar, proximal and distal borders of the navicular bone and the spongiosa were assigned an MRI grade (0–3) and a histological grade and compared statistically. Results: Increased signal intensity in the spongiosa of the navicular bone was associated with a variety of abnormalities, including fat atrophy, with lipocytes showing loss of definition of cytoplasmic borders, a proliferation of capillaries within the altered marrow fat, perivascular or interstitial oedema, enlarged intertrabecular bone spaces, fibroplasia and thinned trabeculae showing loss of bone with irregularly spiculated edges of moth‐eaten appearance. There were significant associations among histological lesions of the fibrocartilage, calcified cartilage and subchondral bone. There were also significant associations between MRI grading of the spongiosa and both histological marrow fat grade and the combined maximum of the MRI grades for the fibrocartilage. Conclusions and potential relevance: Increased signal intensity in the spongiosa of the navicular bone in fat‐suppressed MR images may occur in association with lesions of the fibrocartilage with or without subchondral bone or may represent a separate disease entity, particularly if diffuse, reflecting a variety of alterations of trabecular bone and marrow fat architecture.     

Use of blood culture medium enrichment for synovial fluid culture in horses: A comparison of different culture methods

Reasons for performing study: Standard methods for culturing equine synovial fluid (SF) are often unrewarding. Evidence‐based information on the relative efficiency of different systems used for optimisation of isolation of microorganisms from equine SF is lacking. Objectives: To compare the results of different culture systems performed in parallel on SF samples from horses clinically diagnosed with synovial sepsis. Methods: Synovial fluid specimens were collected between February 2007 and October 2008 from all horses admitted to a referral hospital that were clinically diagnosed with synovial sepsis and from control horses. Synovial fluid samples were cultured in parallel by: 1) direct agar culture (DA); agar culture after: 2) lysis‐centrifugation pretreatment (LC); 3) conventional enrichment (CE); 4) combined LC/CE; or 5) blood culture medium enrichment using an automated system (BACTEC 9050). Results: Ninety SF samples from 82 horses were included, together with 40 control samples. Seventy‐one of 90 samples (79%) were culture‐positive by using blood culture medium enrichment (BACTEC), which was significantly higher compared to all other methods. BACTEC enrichment was never negative while any of the other methods was positive. Although agar culture following LC and/or CE resulted in a slightly higher number of positive samples compared to DA, this difference was not significant. All control samples were culture negative by the 5 different techniques. Although the majority of samples containing isolates recovered without enrichment, culture results after BACTEC enrichment were available on the same day as for agar culture with or without LC (19/23 samples), while CE postponed recovery by at least one day in 20/23 samples. Conclusion: Blood culture medium enrichment is superior to other techniques for isolation of bacteria from SF of horses. The use of an automated system allows enrichment without substantially postponing recovery of microorganisms. Potential relevance: The efficient and fast isolation of microorganisms from infected SF by the BACTEC system allows for rapid susceptibility testing and a more appropriate antibiotic treatment.     

Determination of MMP-2 and -9 activities in synovial fluid of horses with osteoarthritic and arthritic joint diseases using gelatin zymography and immunocapture activity assays

REASON FOR PERFORMING STUDY: Matrix metalloproteinases (MMPs)-2 and -9 activities have been found elevated in synovial fluid from various joint diseases in man. However, in the horse few data are available. OBJECTIVES: To explore the clinical significance of MMP-2 and -9 activities in synovial fluid of horses with different forms of joint diseases. METHODS: Gelatin zymography and MMP-2 and -9 immunocapture activity assays were applied on synovial fluids from control joints and joints with aseptic joint disease (AJD) and septic arthritis (SA). Additionally, MMP-2 and -9 activities were measured in samples from SA to monitor the disease process. RESULTS: Zymographic analysis revealed that samples from AJD and SA contained significantly increased latent MMP-2 activity compared to controls. Samples from SA showed significantly increased monomeric latent MMP-9 activity compared with all other affected joints and controls. Trace amounts of MMP-9 activity, due to the active and dimer form, were detected in samples from SA; however, these bands were absent in samples from AJD and controls. Using immunocapture activity assays, MMP-2 and -9 activities were found to be significantly elevated in joints from SA compared to controls and AJD samples. MMP-2 activity in samples from AJD was significantly increased compared to controls. Both MMP activities decreased in the joints from SA in the course of successful therapy. CONCLUSIONS: Data from zymographic analysis confirmed that MMP-2 and -9 were elevated in equine joint diseases. Immunocapture activity assays have been shown to be suitable for the quantitative determination of MMP-2 and -9 activities in synovial fluid of horses. Both MMP-2 and -9 activities seem to be useful to indicate SA, and MMP-2 activity might be a suitable marker for AJD. POTENTIAL RELEVANCE: These findings encourage the potential use of MMP-2 and -9 as additional aids to clinical investigation. Further work is required to validate the clinical significance of MMP activities in the progress of different joint diseases in horses.     

Non-strangulating intestinal infarction in horses in the UK: A review of 15 cases

The clinicopathological features of 15 horses diagnosed with non-strangulating intestinal infarction (NSII) based on identification of focal areas of intestinal necrosis without mesenteric strangulation were reviewed. The mean age at presentation was 16.3 years, median 13 years, and there was no age, sex, or breed predilection. The major presenting clinical signs included: acute colic ≤ 24 h duration in nine horses; diarrhoea, depression, and inappetence in four horses; and low-grade chronic or recurrent colic, depression, and inappetence in two horses. One horse presented with both acute colic and diarrhoea. Predisposing diseases included colitis or typhlocolitis in five horses and an initial strangulating small intestinal obstruction in three horses, but in seven horses no underlying or predisposing disease was identified. Four cases were managed medically and 11/15 were managed surgically. The most useful diagnostic test was exploratory celiotomy and the only successful treatment was complete resection of the necrotic intestine. Prognosis for survival was poor with a survival rate of only 1/15 (7%). Among the 15 horses, both single and multiple NSII lesions were seen, and they occurred in both the small intestine and large intestines. There was no evidence of Strongylus vulgaris infestation in any of the affected horses.     

Wounds of the pastern and foot region managed with phalangeal casts: 50 cases in 49 horses (1995–2006)

Objective   Describe the use of a phalangeal cast as treatment for wounds in the pastern and foot region of horses. Secondly, to evaluate the healing and soundness of horses treated with phalangeal casts.
Design   Retrospective study of 49 horses.
Procedures   Medical records of 49 horses that were treated with a phalangeal cast for 50 cases of wounds in the pastern and foot region at equine referral hospitals from 1995 to 2006 were reviewed and follow-up information was obtained.
Results   Treatment consisted of wound debridement, lavage, wound closure (28 wounds), cast application and antibiotics (84%). At follow-up, the majority of horses were sound (42 of 47 wounds, 89.4%), three horses were still lame and one horse was euthanased because of persistent lameness. Three horses were lost to follow-up. There was no statistical difference between the outcomes of horses treated acutely (<24 h) or after a 24-h delay. Similarly, the involvement of synovial structures in the wound did not significantly influence outcome.
Conclusions   In this study, wounds involving the pastern and foot that were treated with a phalangeal cast carried a good prognosis for soundness (89.4%) and cosmetic healing (89.5%). The phalangeal casts were well-tolerated and effective.