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.

Tetanus in the equine species: a retrospective study of 31 cases.

BACKGROUND: Few studies exist about factors affecting the outcome of horses with tetanus. ANIMALS: 31 equids (30 horses and 1 donkey) with a clinical diagnosis of tetanus admitted to the Equine Clinic of the University of Liege between 1991 and 2006. The cases were divided into two groups according to the outcome (survivors and non-survivors). METHODS: The clinical data of survivors and non-survivors were compared using an ANOVA (continuous data) or a Fisher's test (discrete data). RESULTS: The survival rate was 32%. Most animals were 5 years or younger, and none had been appropriately vaccinated. The non-survivors were significantly younger than the survivors. The development of dyspnoea, recumbency, and the combination of dysphagia, dyspnoea, and recumbency was observed significantly more in the non-survivors than in the survivors. The timing of tetanus antitoxin administration (either immediately after the onset of suggestive signs or after a delay) was not different between the two groups. The time between the occurrence of a wound and the first signs ranged from 2 days to 2 months and was not significantly different between groups. All non-survivors died within 8 days of the first signs. CONCLUSIONS & CLINICAL IMPORTANCE: This study suggests that young animals are affected more often and more severely by tetanus than older animals. Dyspnoea, recumbency, and the combination of dysphagia, dyspnoea, and recumbency can be considered as indicators of a poor prognosis in equids suffering from tetanus.

Comparative pharmacokinetics of two intravenous administration regimens of tiludronate in healthy adult horses and effects on the bone resorption marker CTX-1.

Bioavailability and pharmacological effects of tiludronate were compared when administered as an intravenous (i.v.) bolus at a dosage of 0.1 mg/kg body weight (b.w.) once daily for 10 consecutive days (group 1, n = 6) and as a single constant rate infusion (CRI) at a total dose of 1 mg/kg b.w. (group 2, n = 6) in healthy adult horses. Tiludronate and carboxy-terminal cross-linking telopeptide of type I collagen (CTX-1) were measured in plasma and urine. There was no statistically significant difference in area under the curve (AUC) and clearance (Cl) between the two groups. Bioavailability of the CRI was 103% (not significantly different) that of the 10 daily i.v. bolus doses. Cumulative urine tiludronate excretion could not be compared between groups because of poor sensitivity of the assay in urine. Plasma and urine CTX-1 levels were not different between groups throughout the study. However, interindividual variations were greater in group 1 than in group 2. A significant decrease in CTX-1 levels was observed in plasma after the first administration in group 1, but not in urine; while in group 2, a significant decrease in CTX-1 concentrations was observed after treatment in both plasma and urine. In conclusion, both dosage regimens of tiludronate produced similar plasma exposure and pharmacological effects in adult healthy horses.

The composition of the inflammatory infiltrate in three cases of polyneuritis equi.

Polyneuritis equi (PNE) is a rare neurological disease in the horse. Because of the suspicion in PNE of a T-lymphocyte mediated immune response against the myelin, the objective of this study was to determine the composition of the inflammatory infiltrate in the involved nerves of 3 horses with PNE, studied retrospectively. T-lymphocytes were demonstrated in the lesions, which suggests a T-lymphocyte mediated immune response against myelin. In addition, the presence of B-lymphocytes indicated a local production of antibodies. More research, involving a prospective study, is needed to determine whether the T-lymphocytes are cytotoxic or T-helper lymphocytes.

Pharmacological effects of tiludronate in horses after long-term immobilization.

INTRODUCTION: Tiludronate, a bisphosphonate, has recently been introduced in veterinary medicine to treat orthopedic conditions in the horse. This study was designed to evaluate its effects on biochemical biomarkers of bone metabolism and on bone density and structure in an experimental model of disuse osteoporosis induced by cast application in horses. METHODS: Two groups of eight horses were immobilized during 8 weeks. The first group (P-group) received a placebo, and the second group (T-group) received tiludronate 1 mg/kg by slow IV infusion. Both treatments were administered twice, 28 days apart. Immobilization consisted of stall rest with the left forelimb packed in a fiberglass cast. It was followed by a 4-week remobilization period and an 8-week standardized training protocol. One biomarker of bone resorption, the C-telopeptides of type I collagen cross-links (CTX-1) and one biomarker of bone formation, the bone isoenzyme of alkaline phosphatase (bone ALP), were assessed. Metacarpus III (MCIII) bone mineral density (BMD) and speed of sound (SOS) were evaluated respectively by dual energy X-ray absorptiometry (DEXA) and quantitative ultrasonography (QUS). Lameness was regularly assessed during the remobilization and training periods. Group- and time-related effects were tested by analysis of variance on repeated measurements. RESULTS: A rapid, transient and significant decrease in CTX-1 concentration was seen after each treatment in the T-group only. No significant differences between groups were seen in the evolution of bone ALP activity. At the end of the experiment, the loss of MCIII BMD measured by DEXA in the immobilized limb was significantly less in the T-group than in the P-group. The MCIII SOS measured by QUS did not significantly vary within or between groups throughout the study. DISCUSSION AND CONCLUSIONS: Tiludronate was found to significantly reduce bone resorption during immobilization, as well as to prevent long-term osteopenia in the immobilized limb. Disuse osteopenia did not affect the lateral superficial cortex of MCIII.

Morphological alterations in oxidative muscles and mitochondrial structure associated with equine atypical myopathy.

REASONS FOR PERFORMING STUDY: There is a lack of well documented studies about muscular lesions in equine atypical myopathy (EAM). OBJECTIVES: To characterise morphopathological changes of striated muscles and myocardium, to progress understanding of this disease. METHODS: Thirty-two horses age 0.5-7 years kept on pasture were referred for a sudden ataxia/myoglobinuria syndrome. Clinical examination (stiffness, muscle pain, muscle fasciculations, abnormal gait, recumbency, myoglobinuria, tachycardia, sweating) and plasma CPK, LDH and AST levels were consistent with extensive myonecrosis and, together with anamnestic data, with so-called 'equine atypical myopathy' (EAM), a disease of unknown aetiology reported since 1939. Macroscopic and microscopic (histology, histoenzymology, ultrastructure) lesions were evaluated. RESULTS: Necropsic examination revealed large areas of muscle necrosis, the extent and severity of which varied between cases and muscles, but which were clearly more constant and severe in respiratory and postural muscles and in the myocardium. Histology highlighted a multifocal and monophasic process compatible with Zenker degeneration/necrosis that mostly and segmentally affected type 1 fibres. Histochemical evaluation revealed a weak and disorganised pattern of NADH tetrazolium reductase staining, the absence of calcium salts precipitates and a dramatic accumulation of lipid droplets. Ultrastructural examination often revealed fibres of which the sole modifications were altered mitochondria and sarcoplasmic lipidosis. CONCLUSIONS: Taken together, the data suggest that a primary alteration of mitochondria should be considered, although secondary mitochondrial abnormalities have yet to be ruled out. POTENTIAL RELEVANCE: The morphological features gathered here reveal that EAM shares most of the characteristics of toxic myopathies.

Atropine reduces dobutamine-induced side effects in ponies undergoing a pharmacological stress protocol.

REASONS FOR PERFORMING STUDY: High-dose dobutamine stress echocardiography has been shown to be cardiotoxic and arrhythmogenic in horses. However, the test may have benefit in practice as a pharmacological challenge of exercise without the treadmill being required. OBJECTIVES: To investigate the effect of low-dose dobutamine on cardiac performance in ponies previously treated with atropine, in order to develop a pharmacological protocol that allows examination of the equine heart under stimulation. METHODS: In 13 healthy Shetland ponies, heart rate (HR), stroke index (SI) and cardiac index (CI) were calculated from pulsed-wave Doppler ultrasound measurements performed at rest and during incremental steps of dobutamine infusion. Group 1 (n = 7) received dobutamine infusion at 2 microg/kg bwt/min for 5 mins followed by incremental rates of 5 microg/kg bwt/min every 5 mins, from 5 to 40 microg/kg bwt/min. Group 2 (n = 6) received dobutamine infusion in incremental rates of 1 microg/kg bwt/min, every 5 mins, from 2 microg/kg bwt/min to 5 microg/kg bwt/min, after premedication with 2 injections of 25 microg/kg bwt of atropine 5 mins apart. RESULTS: The increase in CI during the pharmacological challenge was higher in Group 2 and reached about 2.5 times the resting value. This increase in CI was mediated by a significant increase in HR in both groups, while SI significantly decreased in Group 1 and did not change significantly in Group 2. Ponies of Group 1, but not those of Group 2, showed excessive restlessness and cardiac arrhythmias during the pharmacological challenge and a high intragroup variability in cardiac response. CONCLUSIONS: The results of this study suggest that a low dose of dobutamine in ponies previously given atropine could be a helpful pharmacological protocol to perform stress echocardiography in equids. POTENTIAL RELEVANCE: Further studies should evaluate left ventricular wall motion in horses undergoing low-dose dobutamine protocol after pretreatment with atropine.

Third metacarpal bone mineral density assessment in the standing horse by dual X-ray absorptiometry: suitability, precision and accuracy.

Bone mineral density (BMD) is correlated to mechanical properties of bone. In the horse, dual energy X-ray absorptiometry (DXA) has yet only been performed ex-vivo, but a new portable DXA device would be ideal for in-vivo BMD measurement. We explored field suitability, precision and accuracy of this device for in-vivo third metacarpal density assessment. Precision was analysed by calculating measurement variation under repeated measurement tests with (reproducibility) and without (repeatability) limb repositioning. Repeatability and reproducibility were tested ex-vivo, at the same time that intra- and inter-operator reproducibility were assessed in-vivo. In order to test accuracy, bone mineral content (BMC) of several bone samples determined by DXA and ashing were compared. Repeatability was 1.47% and reproducibility 1.69% ex-vivo. In-vivo reproducibility varied between 2.91 and 4.06% for intra-operator test and between 3.13 and 5.53% for inter-operator test. BMC measured by DXA and ash weight were highly correlated (R2>0.99). In conclusion, under described conditions this DXA device is usable, accurate and precise. Its sensitiveness reaches 8.23% in an individual longitudinal monitoring. Using the third metacarpal bone as an example, we have shown that this device is suitable for experimental or clinical monitoring.