Joke Rijckaert

Motor evoked potentials in standing and recumbent calves induced by magnetic stimulation at the foramen magnum

The aims of this study were to determine reference values for magnetic motor evoked potentials (mMEPs) in calves and the influence of position during examination (standing or lateral recumbency). Reference values were determined using 41 healthy Holstein Friesian bull calves aged 1-10 months; standing and lateral recumbency were examined in 11 calves. Maximal magnetic stimulation was performed at the level of the foramen magnum with a magnetic field of 4 T at the coil surface. In standing position, distinct, reproducible mMEPs were obtained in all calves. Onset latency (LAT) (mean ± standard deviation) was significantly shorter in the thoracic limbs (34.4 ± 3.1 ms) than in the pelvic limbs (44.6 ± 3.0 ms). Amplitude (AMPL) was significantly higher in the thoracic limbs (3.7 ± 1.7 mV) than in the pelvic limbs (3.3 ± 1.7 mV) and significantly increased with body length. Age, body weight, height at the withers and rectal temperature had no significant association with LAT or AMPL, and no differences between left and right were noted. In the lateral position, only 64% of the calves showed responses in the four limbs; in these calves, LAT (29.7 ± 4.7 ms) and AMPL (3.0 ± 1.8 mV) in the thoracic limbs were significantly different from AMPL (47.0 ± 7.4 ms) and LAT (2.1 ± 2.1 mV) in the pelvic limbs. In conclusion, mMEPs in limb muscles can be evoked in calves by stimulation at the level of the foramen magnum. mMEPs are more difficult to obtain in lateral recumbency than in standing calves.

Magnetic motor evoked potential recording in horses using intramuscular needle electrodes and surface electrodes

Abstract To date, motor evoked potential (MEP) recording in animals is often performed using intramuscular monopolar needle electrodes. Their placement and use has several disadvantages. Adhesive surface electrodes appear to be attractive because they are painless and easy to place. Because these are not used in horses, a scouting study is performed to (1) explore the applicability of surface electrodes in horses (2) determine the repeatability of motor latency times (MLTs) and amplitude measurements, and (3) to investigate if MLTs and amplitude values of surface electrode recordings were similar to intramuscular needle electrode recordings. Transcranial MEP recordings were performed by both coated needle and surface electrodes on ten sedated warmblood horses. Mean MLTs for the thoracic limbs were 20.8 ± 1.5 ms for needle and 21.2 ± 1.4 ms for surface electrode recording and 39.4 ± 3.8 ms and 39.2 ± 3.8 ms for the pelvic limbs, respectively. Mean amplitude values were 8.3 ± 4.1 and 7.2 ± 4.7 mV for the thoracic limbs and 4.2 ± 3.1 and 3.8 ± 2.4 mV for the pelvic limbs, respectively. A good agreement and repeatability for MLTs but insufficient agreement and repeatability for amplitude between both recording types were determined by Bland‐Altman plots and Passing‐Bablok regression and coefficients of variation calculation. In conclusion, this preliminary study shows that surface electrode recording of MEP is possible and well tolerated in horses. Surface recordings were repeatable and look similar to the intramuscular recordings when regarding MLTs, but overshadowing effects of large test‐to‐test variations precluded a conclusion concerning amplitude. HighlightsNo systematic or proportional differences between needle and surface electrode recording for latency were present in the thoracic or pelvic limbs.For amplitude, no systematic or proportional differences were present in the pelvic limbs, but there were systematic differences recorded in the thoracic limbs.Surface and needle electrode recording are interchangeable techniques for onset latency but not for amplitude.The use of surface electrodes can be recommended to reduce discomfort in the horse.

Retrospective evaluation of 155 adult equids and 21 foals with tetanus from Western, Northern, and Central Europe (2000–2014). Part 2: Prognostic assessment

OBJECTIVE To identify prognostic variables for adult equids and foals with tetanus. DESIGN Multicenter retrospective study (2000-2014). SETTING Twenty Western, Northern, and Central European university teaching hospitals and private referral centers. ANIMALS One hundred fifty-five adult equids and 21 foals with tetanus. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Variables from history and clinical examination were statistically compared between survivors and nonsurvivors (adults: 49 survivors, 85 nonsurvivors; foals: 7 survivors, 10 nonsurvivors). Cases euthanized for financial reasons were excluded. Mortality rates in adults and foals were 68.4% and 66.7%, respectively. Variables associated with survival in adults included: standing, normal intestinal sounds and defecation, voluntarily drinking, eating soft or normal food, lower heart and respiratory rates, high base excess on admission, longer diagnosis time, treatment and hospitalization delay, and mild severity grade. Variables associated with death included: anorexia, dysphagia, dyspnea, low blood potassium concentration on admission, moderate and severe disease grading, development of dysphagia, dyspnea, recumbency and seizures during hospitalization, treatment with glycerol guaiacolate, intravenous fluids, and intravenous glucose solutions. Variables associated with survival in foals included standing on admission, voluntarily eating soft food and drinking, older age, and longer hospitalization delay. Outcome was not different between different tetanus antitoxin (TAT) dosages, although there was a trend of increasing survival rate with increasing TAT dosages. Cases with appropriate vaccination prior to development of tetanus were rare, but had improved outcome and shorter hospitalization. CONCLUSIONS Prognosis for equine tetanus is poor with similar outcome and prognostic factors in foals and adults. The prognostic assessment of cases with tetanus provides clinicians with new evidence-based information related to patient management. Several prognostic indicators relate to the ability to eat or drink, and more severe clinical signs relate to poor outcome. Increasing intravenous dosages of TAT has no significant effect on outcome, but the positive trend identified may support a recommendation for high intravenous TAT dosages. Further evaluation is warranted.

Retrospective evaluation of 155 adult equids and 21 foals with tetanus in Western, Northern, and Central Europe (2000–2014). Part 1: Description of history and clinical evolution

OBJECTIVE To describe clinical data of hospitalized adult equids and foals with tetanus. DESIGN Multicenter retrospective study (2000-2014). SETTING Twenty Western, Northern, and Central European university teaching hospitals and private referral centers. ANIMALS One hundred fifty-five adult equids (>6 months) and 21 foals (<6 months) with tetanus. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Information on geographic, annual and seasonal data, demographic- and management-related data, clinical history, clinical examination and blood analysis on admission, complications, treatments, and outcomes were described and statistically compared between adults and foals. The described cases were often young horses. In 4 adult horses, tetanus developed despite appropriate vaccination and in 2 foals despite preventive tetanus antitoxin administration at birth. Castration, hoof abscesses, and wounds were the most common entry sites for adults; umbilical cord infections and wounds for foals. Stiffness was the commonest observed initial clinical sign. Blood analyses frequently revealed an inflammatory response, hemoconcentration, muscle damage, azotemia, negative energy balance, liver damage, and electrolyte and acid base disturbances. Common complications or clinical signs developing during hospitalization included dysphagia, dyspnea, recumbency, hyperthermia, seizures, hyperlipemia, gastrointestinal impactions, dysuria, and laryngeal spasms. Cases were supported with wound debridement, antimicrobial treatment, tetanus antitoxin, muscle spasm and seizure control, analgesia, anti-inflammatory drugs, fluid therapy, and nutritional support. Mortality rates were 68.4% in adult horses and 66.7% in foals. Foals differed from adult horses with respect to months of occurrence, signalment, management-related data, potential causative events, clinical signs on admission, blood analysis, complications, and severity grades. CONCLUSIONS This is the first study that rigorously describes a large population of equids affected by tetanus. The information provided is potentially useful to clinicians for early recognition and case management of tetanus in adult horses and foals. Tetanus affects multiple organ systems, requiring broad supportive and intensive care. Neonatal and adult tetanus in the horse should be considered as distinct syndromes, as in human medicine.