G. van Galen

Identification of methylenecyclopropyl acetic acid in serum of European horses with atypical myopathy

REASONS FOR PERFORMING STUDY It is hypothesised that European atypical myopathy (AM) has a similar basis as seasonal pasture myopathy in North America, which is now known to be caused by ingestion of hypoglycin A contained in seeds from the tree Acer negundo. Serum from horses with seasonal pasture myopathy contained the conjugated toxic metabolite of hypoglycin A, methylenecyclopropyl acetic acid (MCPA). STUDY DESIGN Retrospective study on archived samples. OBJECTIVES 1) To determine whether MCPA-carnitine was present in serum of European horses confirmed to have AM; 2) to determine whether Acer negundo or related Acer species were present on AM pastures in Europe. METHODS Concentrations of MCPA-carnitine were analysed in banked serum samples of 17 AM horses from Europe and 3 diseased controls (tetanus, neoplasia and exertional rhabdomyolysis) using tandem mass spectrometry. Atypical myopathy was diagnosed by characteristic serum acylcarnitine profiles. Pastures of 12 AM farms were visited by experienced botanists and plant species were documented. RESULTS Methylenecyclopropyl acetic acid-carnitine at high concentrations (20.39 ± 17.24 nmol/l; range 0.95-57.63 nmol/l; reference: <0.01 nmol/l) was identified in serum of AM but not disease controls (0.00 ± 0.00 nmol/l). Acer pseudoplatanus but not Acer negundo was present on all AM farms. CONCLUSIONS Atypical myopathy in Europe, like seasonal pasture myopathy in North America, is highly associated with the toxic metabolite of hypoglycin A, MCPA-carnitine. This finding coupled with the presence of a tree of which seeds are known to also contain hypoglycin A indicates that ingestion of Acer pseudoplatanus is the probable cause of AM. This finding has major implications for the prevention of AM.

European outbreaks of atypical myopathy in grazing equids (2006-2009). Spatiotemporal distribution, history and clinical features

REASONS FOR PERFORMING STUDY Improved understanding of the epidemiology of atypical myopathy (AM) will help to define the environmental factors that permit or support the causal agent(s) to exert toxicity. OBJECTIVES This European survey of AM aimed to describe spatiotemporal distribution, survival, clinical signs, circumstances in which AM develops and its different expressions between countries and over time. METHODS The spatiotemporal distribution, history and clinical features of AM cases reported to the Atypical Myopathy Alert Group from 2006 to 2009 were described. Comparisons of data from the most severely affected countries and from the large outbreaks were made with Fishers exact and Welchs tests with Bonferroni correction. RESULTS Of 600 suspected cases, 354 met the diagnostic criteria for confirmed or highly probable AM. The largest outbreaks occurred during the autumns of 2006 and 2009 in Belgium, France and Germany. For the first time, donkeys, zebras and old horses were affected, and clinical signs such as gastrointestinal impaction, diarrhoea, penile prolapse, buccal ulceration and renal dysfunction were observed. Affected horses spent >6 h/day on pastures that almost always contained or were surrounded by trees. The latency period was estimated at up to 4 days. Overall survival rate was 26%. Although differences between countries in affected breeds, body condition, horse management and pasture characteristics were recognised, the common presenting clinical signs and mortality were similar between countries. CONCLUSIONS AND POTENTIAL RELEVANCE This study describes new data on case details, history and clinical course of AM that is of preventive, diagnostic and therapeutic value. However, the true impact of the findings of this study on the development of or severity of AM should be tested with case-control studies.

European outbreaks of atypical myopathy in grazing horses (2006–2009): determination of indicators for risk and prognostic factors

REASONS FOR PERFORMING STUDY Appropriate management of atypical myopathy (AM) requires the establishment of an accurate diagnosis and prognosis. Furthermore, preventive measures to avoid AM need to be refined. OBJECTIVES The aims of the study were as follows: 1) to improve the diagnosis of AM; 2) to identify prognostic predictors; and 3) to refine recommended preventive measures based on indicators of risk factors. METHODS An exploratory analysis of cases in Europe between 2006 and 2009 reported to the Atypical Myopathy Alert Group was conducted. Based on clinical data, reported cases were allocated into 2 groups: confirmed or highly probable AM (AM group; further divided into survivors and nonsurvivors); and cases with a low probability of having AM or with another final diagnosis (non-AM group). Using Welchs test and odds ratios corrected for multiple comparisons, the AM vs. non-AM groups were compared to identify indicators for diagnosis and risk factors, and survivors vs. nonsurvivors in the AM group were compared to identify prognostic factors. Sensitivity, specificity and positive and negative predictive values were calculated for specific clinical signs related to final diagnosis and outcome. RESULTS From 600 reported cases, 354 AM cases (survival rate of 26%) and 69 non-AM cases were identified, while there were insufficient data to categorise the remainder. Variables valuable for diagnosing AM compared with similar diseases were as follows: presence of dead leaves and wood and/or trees on pastures; sloping pastures; full-time pasture access; no food supplementation; normal body condition; pigmenturia; normothermia; and congested mucous membranes. Nonsurvival was associated with recumbency, sweating, anorexia, dyspnoea, tachypnoea and/or tachycardia. Survival was associated with remaining standing most of the time, normothermia, normal mucous membranes, defaecation and vitamin and antioxidant therapy. CONCLUSIONS AND POTENTIAL RELEVANCE This study refines the list of risk factors for AM. Clinical signs valuable for diagnosis and prognosis have been identified, enabling clinicians to improve management of AM cases.

Clinical Diagnosis of West Nile Fever in Equids by Classification and Regression Tree (CART) Analysis and Comparative Study of Clinical Appearance in Three European Countries

This retrospective study describes risk/protection factors for the development of clinical West Nile Fever (WNF) in equids, compares clinical presentation in three European countries, France, Italy and Hungary, and creates classification and regression trees (CART) to facilitate clinical diagnosis. The peak of WNF occurrence was observed in September whatever the country. A significant difference between Italy and France was observed in the delay between initial clinical signs and veterinary consultation. No clinical sign was significantly associated with WNF. Despite similar clinical presentations in the three countries, occurrence of hyperthermia was more frequently reported in France. Classification and regression tree demonstrated the major importance of geographical locality and month to reach a diagnosis and emphasized differences in predominant clinical signs depending on the period of detection of the suspected case (epizootic or not). However, definite diagnosis requires specific serological tests. Centralized reporting system and time-space risk mapping should be promoted in every country.

The Use of Radial Extracorporeal Shockwave Therapy in the Treatment of Urethral Urolithiasis in the Horse: A Preliminary Study

BACKGROUND Radial extracorporeal shockwave therapy (ESWT) is widely used in equine practice for the treatment of orthopedic problems. However, its original use as a lithotripsy device in human and canine urology led us to postulate that it could be used as an alternative to the surgical treatment of urethral calculi in horses. HYPOTHESIS Radial ESWT can easily and safely fragment calculi in the distal urethra of the horse. ANIMALS Two postmortem cases and 1 live case of obstructive urinary disease admitted at the Veterinary Teaching Hospital of Liege. METHODS A radial shockwave device was directly applied to the urethra in an attempt to fragment calculi. An ex vivo trial was performed on the same retrieved calculi to investigate pressure settings in order to obtain complete fragmentation of the calculus. RESULTS In all cases, radial ESWT was able to fragment the calculus partially, enabling retrieval of the remaining fragments via the urethra. Much higher pressure settings than those used for in vivo partial fragmentation were necessary to obtain complete destruction of the calculi ex vivo. CONCLUSIONS AND CLINICAL IMPORTANCE This brief report suggests the use of radial ESWT as a safe and useful alternative to more invasive surgical management of urethral calculi in horses.

Vegetative Endocarditis in Equids (1994–2006)

BACKGROUND Endocarditis is a rare heart condition with variable clinical expressions in equids. Risk factors for this disease are incompletely understood. OBJECTIVE Describe risk factors for endocarditis in equids. ANIMALS One hundred and fifty-three equids admitted to Liège University, 9 diagnosed with endocarditis and 144 free from endocarditis but admitted to the hospital with a differential diagnosis including this disease. METHODS Retrospective case-control study. RESULTS Equids with endocarditis were significantly younger (mean age = 4.84 +/- 5.74 years) than control equids (mean age = 10.8 +/- 7.73 years) (P = .01). No sex or breed predisposition was observed. Animals with hyperthermia (odds ratio [OR] = 24.4; confidence interval [CI] = 1.40-428), synovial distension (OR = 13.4; CI = 3.00-59.8), lameness (OR = 6.52; CI = 1.63-26.1), hyperglobulinemia (OR = 26.4; CI = 3.03-229), hypoalbuminemia (OR = 11.4; CI = 1.34-96.8), hyperfibrinogenemia (OR = 9.81; CI = 1.16-82.7), or leukocytosis (OR = 7.12; CI = 1.40-36.4) presented a significantly higher risk of having endocarditis than control horses. The presence of two of the clinical signs mentioned above significantly increased the probability of a diagnosis of endocarditis (P< or = .05). CONCLUSIONS AND CLINICAL IMPORTANCE Age is associated with equine endocarditis. The diagnostic value of certain clinical signs and abnormalities in blood parameters in this disease are described.

Traditional and Quantitative Assessment of Acid-Base and Shock Variables in Horses with Atypical Myopathy

BACKGROUND Descriptions of acid-base disturbances in atypical myopathy (AM) are limited. OBJECTIVES Describe and compare traditional and quantitative acid-base abnormalities and cardiovascular shock status in horses with AM at admission. ANIMALS 34 horses with AM, 15 healthy controls. METHODS Retrospective case-control study. Records were searched for shock variables (packed cell volume [PCV], blood urea nitrogen [BUN], heart and respiratory rate) and acid-base variables (venous blood gas analysis, electrolytes, total protein, lactate) on admission. Base excess (BE) of free water (BEfw), chloride (BEcl), total protein (BEtp), and unidentified anions (BEua), anion gap (AG), measured strong ion difference (SIDm), and concentration of total nonvolatile weak acids ([Atot]) were calculated. Acid-base classifications, using simplified strong ion model and traditional approach, and shock grades were assigned. A 2-sample Wilcoxon rank-sum test and Bonferroni correction compared variables in AM cases versus control horses. Significance was P < .05/16 for acid-base and P < .05/5 for shock variables. RESULTS Tachycardia, tachypnea, and normal to increased PCV and BUN were common in AM cases. Respiratory, metabolic acid-base alterations, or both were mainly caused by respiratory alkalosis, lactic acidosis, and SIDm alkalosis, alone or in combination. Evaluated variables (except pH, potassium concentration, total protein, and related calculations) were significantly different (P < .001) between AM cases and control horses. The strong ion model provided a more accurate assessment than the traditional approach and identified mixed derangements. CONCLUSIONS AND CLINICAL IMPORTANCE Acid-base derangements should be evaluated in horses with AM and this preferably with the strong ion model.

Clinical Sentinel Surveillance of Equine West Nile Fever, Spain.

West Nile fever (WNF) is a viral zoonotic infection caused by a mosquito-borne flavivirus of the Flaviviridae family. According to a comparative study, the passive surveillance of horses by equine veterinarians appeared to be the most cost-effective system in the European context of WNF. Clinical data issued from a passive epidemiosurveillance network from September 2010 to December 2011 on horses in Spain were statistically compared and used to develop a predictive diagnostic decision tree, both with the aim to improve the early clinical detection of WNF in horses. Although clinical signs were variable in horses affected by WNF, four clinical signs and the month of occurrence were identified as useful indicators to distinguish between WNF-related and WNF-unrelated cases. The signs that pointed out a presumptive diagnosis of WNF in horses were cranial nerves deficits, limb paralysis, photophobia and nasal discharge. Clinical examination of horses with neurological signs that are not vaccinated against WNV could provide important clues for the early clinical detection of WNF and therefore serve as an alert for possible human viral infections. The study of the clinical pattern of WNF in horses is of importance to enhance awareness and better understanding and to optimize surveillance designs for clinical detection of WNF in horses in advance of epidemic activity affecting humans.

European outbreaks of atypical myopathy in grazing equids (2006-2009)

REASONS FOR PERFORMING STUDY Improved understanding of the epidemiology of atypical myopathy (AM) will help to define the environmental factors that permit or support the causal agent(s) to exert toxicity. OBJECTIVES This European survey of AM aimed to describe spatiotemporal distribution, survival, clinical signs, circumstances in which AM develops and its different expressions between countries and over time. METHODS The spatiotemporal distribution, history and clinical features of AM cases reported to the Atypical Myopathy Alert Group from 2006 to 2009 were described. Comparisons of data from the most severely affected countries and from the large outbreaks were made with Fishers exact and Welchs tests with Bonferroni correction. RESULTS Of 600 suspected cases, 354 met the diagnostic criteria for confirmed or highly probable AM. The largest outbreaks occurred during the autumns of 2006 and 2009 in Belgium, France and Germany. For the first time, donkeys, zebras and old horses were affected, and clinical signs such as gastrointestinal impaction, diarrhoea, penile prolapse, buccal ulceration and renal dysfunction were observed. Affected horses spent >6 h/day on pastures that almost always contained or were surrounded by trees. The latency period was estimated at up to 4 days. Overall survival rate was 26%. Although differences between countries in affected breeds, body condition, horse management and pasture characteristics were recognised, the common presenting clinical signs and mortality were similar between countries. CONCLUSIONS AND POTENTIAL RELEVANCE This study describes new data on case details, history and clinical course of AM that is of preventive, diagnostic and therapeutic value. However, the true impact of the findings of this study on the development of or severity of AM should be tested with case-control studies.

European outbreaks of atypical myopathy in grazing equids (2006-2009): Spatiotemporal distribution, history and clinical features: Outbreaks of atypical myopathy: spatiotemporal distribution, history and clinical features

REASONS FOR PERFORMING STUDY Improved understanding of the epidemiology of atypical myopathy (AM) will help to define the environmental factors that permit or support the causal agent(s) to exert toxicity. OBJECTIVES This European survey of AM aimed to describe spatiotemporal distribution, survival, clinical signs, circumstances in which AM develops and its different expressions between countries and over time. METHODS The spatiotemporal distribution, history and clinical features of AM cases reported to the Atypical Myopathy Alert Group from 2006 to 2009 were described. Comparisons of data from the most severely affected countries and from the large outbreaks were made with Fishers exact and Welchs tests with Bonferroni correction. RESULTS Of 600 suspected cases, 354 met the diagnostic criteria for confirmed or highly probable AM. The largest outbreaks occurred during the autumns of 2006 and 2009 in Belgium, France and Germany. For the first time, donkeys, zebras and old horses were affected, and clinical signs such as gastrointestinal impaction, diarrhoea, penile prolapse, buccal ulceration and renal dysfunction were observed. Affected horses spent >6 h/day on pastures that almost always contained or were surrounded by trees. The latency period was estimated at up to 4 days. Overall survival rate was 26%. Although differences between countries in affected breeds, body condition, horse management and pasture characteristics were recognised, the common presenting clinical signs and mortality were similar between countries. CONCLUSIONS AND POTENTIAL RELEVANCE This study describes new data on case details, history and clinical course of AM that is of preventive, diagnostic and therapeutic value. However, the true impact of the findings of this study on the development of or severity of AM should be tested with case-control studies.