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By Timothy G. Eastman, DVM, DACVS, MPVM Published in Bay Area Equestrian Network March 2008 The pastern joint, also known as the proximal interphalangeal joint, is a relatively common source of lameness in horses (Figure 1: Note the smooth borders of the bones along the front of the pastern joint of this normal horse). Degenerative joint disease/arthritis of this joint is commonly referred to as high ringbone. Low ringbone refers to the same type of degenerative joint disease of the coffin joint and is much less common. Horses afflicted with high ringbone are difficult to keep sound. The area is similar to the lower hock joints in that it is a “high-load/low motion” joint, meaning the joint is subjected to a lot of pressure but undergoes very little movement. Unlike the lower hock joints, the pastern joint does not respond consistently to intra-articular injections. The diagnosis of high ringbone is based on localizing the source of the lameness to the pastern joint with nerve and/or joint blocks. Lameness can be classified as minor and only apparent with extreme exercise or severe enough to cause lameness at a walk. Radiographs and ultrasound are useful in confirming the diagnosis and determining the severity of the disease. Radiographically you see new bony growth along the front and the sides of the joint (Figure 2: Compare the new bony growth along the front of this arthritic pastern joint to the normal one in Figure 1). These bony prominences can sometimes be seen and felt prior to radiographs during the physical examination. If the disease was traumatic in origin, ultrasound can be particularly useful in identifying any concurrent soft-tissue injuries complicating the prognosis. A complete series of radiographs is necessary to determine the severity of the disease as the sides of the joint can only be seen on oblique views. Quarter Horses are predisposed to ringbone due to the rotational forces they exert on their lower limbs during the sudden stopping and turning common in Western Performance. Treatment of ringbone can be divided into medical and surgical options. Medical management of ringbone is aimed at slowing down the progression of cartilage degeneration and reducing pain and inflammation associated with the condition. Helping to “ease the breakover” of the foot will decrease the forces subjected to the front of the joint and can be accomplished by a farrier “squaring” the toe and “rolling” the shoe. Like any lameness condition, there are many ways to shoe for the same problem. Anti-inflammatories like Phenylbutazone (“bute”) are used to decrease inflammation associated with acute flare-ups of the condition and to manage horses on a long-term basis. Many horses with ringbone can be sound enough for light use by giving bute before and after exercise. Oral joint supplements alone are unlikely to be sufficient to provide relief but are thought by some to slow down the progression of the disease. More aggressive joint supplementation would include Legend? and/or Adequan?. Legend is an intravenous form of hyaluronic acid which is important in lubrication of joints and is an essential component of joint fluid. Some horses with ringbone will be sound enough for athletic use with Legend therapy alone. Adequan is an intra-muscular injection and is thought to delay the progression of cartilage degeneration. Injecting the pastern joint is not rewarding as consistently as some other joints but should be attempted to evaluate an individual horse’s response. There is tremendous variability with regards to how long an individual horse will respond to pastern joint injections. If controlling the disease with anti-inflammatories, shoeing changes and joint therapy is not sufficient to allow pain free performance, surgically fusing the joint may be the only option to provide pain free performance. While this procedure involves a major surgery, it offers the possibility of complete return to work and relief from pain for many horses. Research has shown that 2 out of 3 horses with ringbone of the forelimbs and greater than 4 out of 5 horses with hindlimbs affected will be sound enough for athletic use with surgical fusion. This joint is fused with a combination of plates and screws (Figure 3). Typically horses are maintained in a cast for several weeks, then a bandage and stall rest for several months prior to returning to full work. As with any lameness condition, your veterinarian and farrier need to work together to provide your horse with the highest level of soundness possible and to help you determine the best course of action for your particular horse.

By Richard A.Mansmann, Sarah James, Anthony T.Blikslager, Kurtvom Orde Published in the Journal of Equine Veterinary Science (Purchase access to read the complete article) Abstract This study deals with the relationship between long toes in the hind feet and pain in the gluteal region in horses, and the remedial value of trimming/shoeing that moves the breakover point back at the toe. 77 client-owned horses were studied, 67 shod riding horses retrospectively and 10 barefoot broodmares prospectively. The 10 mares were evaluated twice, and 24 of the 67 riding horses were re-evaluated at the next shoeing, for a total of 111 observations. Each horse underwent gluteal palpation and lateral radiographs of both hind feet. Toe length was quantified as breakover distance (BD), the horizontal distance between the tip of the third phalanx and the dorsalmost point at which the wall/shoe was in contact with the ground. The BD was then shortened with trimming +/− shoeing to a length of ≤15mm (shod horses) or ≤20 mm (barefoot horses). The 24 riding horses were re-evaluated 4-6 weeks later and the 10 broodmares 1 week after trimming. The results showed that of the 67 riding horses, 75% were positive for gluteal pain at initial evaluation. The mean BD for the positive and negative horses was 24.2 ± 1.3 mm and 18.8 ± 2.0 mm, respectively (p = 0.04). At the next shoeing, the mean BD was 10.9 ± 2.3 mm and gluteal pain was improved in all 24 horses; 20 horses (83%) were negative and 4 horses (17%) were now only mildly positive. The 10 broodmares were all positive for gluteal pain initially. The mean BD before and after trimming was 23.7 ± 1.2 mm and 10.9 ± 1.1 mm, respectively. One week later, gluteal pain was improved in all 10 mares; 8 mares (80%) were negative, and the other 2 mares (20%) were only mildly positive. The conclusion is that excessive toe length in the hind feet may be accompanied by pain in the gluteal region and, in our experience, may be associated with gait or performance problems. Shortening the toe can alleviate this pain within days or weeks. Aiming for a BD of between 0 and 20 mm probably is appropriate for the average-size horse.

By Verena K. Affolter, Dominic Dawson, Keita Iyori, Koji Nishifuji, Thierry Olivry, Catherine A. Outerbridge, Anna C. Renier, Yu Hsuan Wang, Stephen D. White, and Laramie D. Winfield Published in the Equine Veterinary Journal (Purchase access to read the complete article) Abstract Hypothesis/Objectives: To describe the clinical, histological and immunological findings of an equine case of pemphigus vulgaris, including the demonstration of antidesmoglein (anti-Dsg) autoantibodies. Case Report: The diagnosis of pemphigus vulgaris was confirmed in a 9-year-old Welsh pony stallion with both direct and indirect immunofluorescence and immunoprecipitation studies, the latter identifying circulating anti-Dsg3 IgG. Treatment with immunosuppressive medications was initiated. Lesions were seen in the perineal area, sheath, mane, tail, eyelids, coronary bands and mucosa of the mouth and oesophagus. Initial corticosteroid treatment improved the clinical signs, but the onset of laminitis necessitated a reduction in dosage, which was associated with a recurrence of lesions and development of oral ulcers. A corneal ulcer developed after 60 days of treatment. Despite treatment with azathioprine, gold salts and dapsone, the disease progressed and the pony was euthanized. Postmortem examination showed additional lesions of the cardia of the stomach. Conclusions and Clinical Importance: Pemphigus vulgaris is rarely diagnosed in equids. We describe a case that was substantiated by the demonstration of anti-Dsg3 IgG. Response to treatment was poor, with the best response to high doses of prednisolone. Equine pemphigus vulgaris is likely to carry a poor prognosis and if there is no response to treatment, humane euthanasia is warranted.

By M. Aleman, P. H. Kass, J. E. Madigan, K. G. Magdesian, N. Pusterla, and L. S. Winfield Published in the Equine Veterinary Journal (Purchase access to read the complete article) Abstract Summary: Reasons for performing study There are currently few data available on the prognosis and outcome of recumbent horses. Objectives: To investigate the outcome of hospitalised horses that had been recumbent in the field or hospital and factors affecting their survival within the first 3 days of hospitalisation and survival after 3 days to hospital discharge. Study Design: Retrospective analysis of clinical records. Methods: Records of 148 horses admitted to the William R. Pritchard Veterinary Medical Teaching Hospital, University of California Davis from January 1995 to December 2010 with a history of recumbency or horses that became recumbent while hospitalised were evaluated. Exact logistic regression was used to assess the association between clinical parameters and survival within the first 3 days of hospitalisation and survival to hospital discharge after 3 days. Results: There were 109 nonsurvivors and 39 survivors. Multivariate analysis showed variables associated with an increased odds of death within the first 3 days of hospitalisation included duration of clinical signs prior to presentation, with horses showing clinical signs for over 24 h having increased odds of death (P = 0.043, odds ratio [OR] 4.16, 95% confidence interval [95% CI] 1.04–16.59), the presence of band neutrophils (P = 0.02, OR 7.94, 95% CI 1.39–45.46), the horse not using the sling (P = 0.031, OR 4.22, 95% confidence interval 1.14–15.68) and horses that were unable to stand after treatment (P<0.0001, OR 231.15, 95% CI 22.82–2341.33). Increasing cost was associated with lower odds of death (P = 0.017, OR 0.96, for each additional $100 billed, 95% CI 0.93–0.99). Conclusions: This study demonstrates that the duration of clinical signs, response to treatment and the ability of horses to use a sling are associated with survival to hospital discharge for recumbent horses.

Hemorrhage and blood loss–induced anemia associated with an acquired coagulation factor VIII inhibitor in a Thoroughbred mare By Laramie S. Winfield, DVM and Marjory B. Brooks, DVM Published in the Journal of the American Veterinary Medical Association (Purchase access to read the complete article) Abstract Case Description: A 23-year-old Thoroughbred mare was evaluated because of a coagulopathy causing hemoperitoneum, hematomas, and signs of blood loss–induced anemia. Clinical Findings: The mare had tachycardia, pallor, hypoperfusion, and a large mass in the right flank. The mass was further characterized ultrasonographically as an extensive hematoma in the body wall with associated hemoabdomen. Coagulation testing revealed persistent, specific prolongation of the activated partial thromboplastin time (> 100 seconds; reference interval, 24 to 44 seconds) attributable to severe factor VIII deficiency (12%; reference interval, 50% to 200%). On the basis of the horse’s age, lack of previous signs of a bleeding diathesis, and subsequent quantification of plasma factor VIII inhibitory activity (Bethesda assay titer, 2.7 Bethesda units/mL), acquired hemophilia A was diagnosed. The medical history did not reveal risk factors or underlying diseases; thus, the development of inhibitory antibodies against factor VIII was considered to be idiopathic. Treatment and Outcome: The mare was treated with 2 transfusions of fresh whole blood and fresh-frozen plasma. Immunosuppressive treatment consisting of dexamethasone and azathioprine was initiated. Factor VIII deficiency and signs of coagulopathy resolved, and the inhibitory antibody titer decreased. The mare remained healthy with no relapse for at least 1 year after treatment. Conclusions and Clinical Relevance: Horses may develop inhibitory antibodies against factor VIII that cause acquired hemophilia A. A treatment strategy combining transfusions of whole blood and fresh-frozen plasma and administration of immunosuppressive agents was effective and induced sustained remission for at least 1 year in the mare described here.

By Monica Aleman, Danika L. Bannasch, Carrie J. Finno, Steven R. Hollingsworth, John E. Madigan, Ron Ofri, and Laramie Winfield Published in the Equine Veterinary Journal (Purchase access to read the complete article) Abstract Objective: Neuroaxonal dystrophy (NAD) is a disease characterized by the sudden onset of neurologic signs in horses ranging from 4 to 36 months of age. Equine degenerative myeloencephalopathy (EDM), a disease that has been associated with low vitamin E concentrations, is considered a more advanced form of NAD. The objective of this report is to describe the electrophysiological features of NAD/EDM in American Quarter horses (QHs). Horses: Six NAD/EDM-affected QHs and six unaffected QHs were evaluated by ophthalmic examination and electroretinography. Five of the NAD/EDM-affected QH and five unaffected QHs were also evaluated by electroencephalography (EEG). Results: Ophthalmic examination, ERGs, and EEGs were unremarkable in NAD/EDM cases. Conclusions: Neuroaxonal dystrophy/EDM does not appear to cause clinical signs of ocular disease or functional ERG/EEG deficits in QHs.

Long-term Outcome of Standing Medial Patellar Ligament Splitting to Manage Horses Exhibiting Delayed Patellar Release: 64 Horses By Sarah J. James, Timothy G. Eastman, and Justin D. McCormick Published in the Journal of Equine Veterinary Science (Purchase access to read the complete article) Abstract A standing surgical technique for splitting the medial patellar ligament is described, and the long-term (average 4.5-years) efficacy of the procedure in horses exhibiting delayed patellar release is reported. Medical records of 64 horses that underwent a standing medial patellar ligament splitting surgery performed to treat delayed patellar release were analyzed retrospectively. Horses were sedated in standing stocks. A number 15 scalpel blade was used to percutaneously split the medial patellar ligament from just proximal to its insertion on the tibial tuberosity to its attachment on the parapatellar fibrocartilage, with the goal of inducing a localized desmitis and subsequent thickening of the ligament. Aftercare consisted of oral antibiotics, 14 days stall rest with hand walking, light exercise for 14 days, and full work at 4 weeks. Follow-up information was obtained through telephone calls to owners and/or clinical evaluation by a veterinarian. Results showed that 89% of horses benefitted from the procedure, with complete resolution in 58% of horses and improvement in 31% of horses. A total of 73% of horses were able to perform at the desired level following the procedure; 63% of horses showed signs of improvement or resolution within 30 to 60 days. Two horses had complications following the procedure: 1 horse had an incisional infection, and 1 had a medial patellar ligament rupture. This study shows that standing medial patellar ligament splitting is a successful, long-term surgical option for treatment of delayed patellar release. The procedure has few complications and allows rapid return to desired performance.