Needle electromyography in the horse compared with its principles in man: a review.
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Action Potentials↗
Biomedical subjects
H J Breukink
Publications and source records attributed to H J Breukink.
Quantitative motor unit action potential analysis of skeletal muscles in the Warmblood horse.
Motor unit action potential (MUP) analysis in human medicine is a valuable and important diagnostic technique enabling discrimination between myogenic and neurogenic problems. This study establishes normative data in subclavian, triceps and lateral vastus muscles for clinical application of MUP analysis in the Warmblood horse, and examines whether muscle differences are present. Electromyographic (EMG) needle examination and MUP analysis were performed of the triceps, lateral vastus and subclavian muscles in 7 awake, nonsedated, Warmblood horses age 4-10 years. The amplitude, duration, number of phases and turns were calculated from the recorded superimposed MUPs together with intramuscular and rectal temperatures. No significant differences were found in duration of insertional activity between the 3 muscles. The mean +/- s.d. duration of the insertional activity was 526 +/- 1483 ms. The MUP amplitude of all 3 muscles differed significantly, with the highest amplitude (427 +/- 3.20 microV) in the triceps and the lowest (220 +/- 2.08 microV) in the subclavian muscle. The number of turns of the lateral vastus (3.0 +/- 1.22) was significantly higher than that of the triceps muscle (2.7 +/- 1.51). No differences were found in MUP duration (5.9-6.4 ms).
Action Potentials↗
[Bronchoaveolar lavage for the diagnosis of lower airway disorders in horses].
Equine pulmonary disease and especially the terminology of lower airway disease have been subject to discussion. Besides established terms such as 'Chronic Obstructive Pulmonary Disease' (COPD) and Chronic bronchitis, the term 'small airway disease' (SAD) has been introduced, for respiratory disease with inflammation in the lower airways in combination with exercise intolerance. Bronchoalveolar lavage (BAL) enables the practitioner to diagnose SAD in an early stage when there are no other signs such as coughing or exudate in the trachea. The BAL fluid is microscopically examined after centrifugation. BAL cytology, especially neutrophilia, eosinophilia, and an increase in mast cells, is important, not only to decide whether SAD is present but also to determine in the choice of therapy.
Animals↗
[Risks in treating sport horses].
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Animals↗
Weaning and the weanling diet influence the villous height and crypt depth in the small intestine of pigs and alter the concentrations of short-chain fatty acids in the large intestine and blood.
Effects of weaning pigs to different diets have been investigated in terms of the changes in the small intestinal morphology, and in the absorption of short-chain fatty acids (SCFA) and sodium from the large intestine. One piglet from each of six litters containing nine pigs was sampled on the day of weaning; the other eight piglets were divided into four equal groups and fed different diets as follows: unweaned, weanling diet, or sow's milk at high or low level. Four and seven days after weaning, measurements of the intestinal tissue and contents were made; the plasma concentrations of SCFA, aldosterone and sodium were also measured. The villous height in the small intestine was highest in the unweaned group and greater in the high milk group than in either the weanling diet or low milk group (P < 0.001). Apparently, villous atrophy was due more to the level of feed intake than to the composition of the diet. The concentrations of SCFA in the large intestine and portal blood were highest in the weanling diet group and lowest in the low milk group. The low milk group tended to have higher blood concentrations of aldosterone (P = 0.15), which may have compensated for the low concentrations of SCFA in maintaining a higher percentage of dry matter in the intestine. Pigs fed weanling diet may use the energy from the SCFA to maintain a body weight comparable to that of pigs fed milk at a low level.
Aldosterone↗
Role of the large intestine in the pathogenesis of diarrhea in weaned pigs.
OBJECTIVE: To determine whether the large intestine may have a role in counterbalancing the loss of fluid from the small intestine of pigs with diarrhea. ANIMALS: 2 groups of pigs (1 from a specific-pathogen-free herd and 1 from a herd with a history of diarrhea). PROCEDURE: At weaning and 4, 7, 11, and 14 days after weaning, the percentage of dry matter in the large intestinal contents, total and individual concentrations and volatile fatty acids in large-intestinal contents and blood, and concentration of aldosterone in the blood were measured. RESULTS: Large intestinal contents of pigs with diarrhea had a lower percentage of dry matter, lower acetate and butyrate concentrations, and higher propionate concentrations than did those of specific-pathogen-free pigs, and blood of pigs with diarrhea also had lower total volatile fatty acids concentration, higher aldosterone concentration, and lower sodium concentration. CLINICAL RELEVANCE: The large intestine has a role in the pathogenesis of diarrhea in weaned pigs.
Aging↗
Weaning piglets, microbial fermentation, short chain fatty acids and diarrhoea.
The effect of weaning on the absorptive capacity of the large intestine (LI) of weaned and unweaned pigs for short chain fatty acids (SCFA), sodium, potassium, and water has been determined by perfusion studies. Ligated loops were formed at four sites in the LI. In both groups the rate of absorption of SCFA, sodium and potassium was increased from the proximal to the distal sites, but this increase was not followed by an increase in the absorption of water. It is concluded that unweaned and weaned pigs can absorb SCFA and electrolytes immediately after weaning, but that a period of adaptation is required for the optimal absorption of water. This lower capacity for the absorption of water in the first two weeks after weaning makes the recently weaned pig vulnerable to a loss of fluid from the intestines.
Adaptation, Physiological↗
Characterization of muscarinic receptors in equine tracheal smooth muscle in vitro.
This study was undertaken to assess the importance of muscarinic receptor subtypes in equine airway disease. Smooth muscle strips from the mid-cervical portion of the trachea of horses were placed in tissue baths and isometric contractile force was measured. Active force was measured in response to metacholine and the selective muscarinic receptor agonists McN-A-343 (M1-selective) and pilocarpine (M2-selective) in cumulative concentrations (10(-9)M through 10(-3)M), with and without preincubation with three or four concentrations of the selective muscarinic receptor antagonists pirenzepine (M1-selective), methoctramine (M2-selective), and 4-DAMP (M3-selective). The tissues contracted in response to all muscarinic agonists. The maximum responses (mean +/- sem) were 86.7 +/- 6.2 g for metacholine, 27.1 +/- 2.5 g for McN-A-343 and 37.6 +/- 3.5 g for pilocarpine. Preincubation with the selective muscarinic receptor antagonists resulted in dose-dependent rightward shifts of the concentration-effect curves for metacholine. pA2 values (means +/- sem) were 8.88 +/- 0.30 for 4-DAMP, 6.53 +/- 0.38 for methoctramine, and 6.72 +/- 0.31 for pirenzepine. Preincubation with 10(-7) M 4-DAMP resulted in a rightward shift of the concentration-effect curves for McN-A-343 and pilocarpine. These results indicate that the most important muscarinic receptor mediating contraction of equine tracheal smooth muscle is of the M3-type. Therefore relatively low concentrations of a M3-selective muscarinic receptor antagonist will inhibit acetylcholine-induced contraction of equine airway smooth muscle.
Animals↗
A survey of horses with acute diarrhoea: diagnosis, assessment of the prognosis, and comparison of two antibiotic therapies.
Twenty horses, ponies, and foals referred with acute diarrhoea were divided at random into two treatment groups. One group was treated intravenously with trimethoprim/ sulfadiazine and the other group with ampicillin/gentamicin. Both groups were given the same standardized symptomatic therapy. All animals were evaluated clinically and 5 variables (general impression, heart rate, rectal temperature, appetite, and consistency of the faeces) were estimated on a five point scale (0-4). Jugular blood samples were taken at admittance and at regular intervals for routine screening. Three blood variables (packed cell volume, white blood cell count, and base excess) were also classified in a 5-point scale. The 'diarrhoea prognosis index' was the total sum of the eight variables scaled. Faecal samples were cultured aerobically and examined for worm eggs and larvae. A definite diagnosis was only reached in 11 horses (55%). Salmonellosis and parasitic infections were the most common causes of the diarrhoea. Seven horses (35%), three from the ampicillin/gentamicin group and four from the trimethoprim/sulfadiazine group, died or were euthanized because of a poor prognosis. Only the packed cell volume differed significantly between horses that died and horses that survived. No single clinical or haematological/biochemical variable did forecast the prognosis for the individual patient reliably, nor did the 'diarrhoea prognosis index'. The only reliable indication for the outcome of an individual horse appeared to be the clinical response to treatment within 4 days. The clinical outcome of both treatment groups did not differ significantly. In conclusion, it was difficult to reach a specific diagnosis in these horses with diarrhoea. It was not possible to forecast the prognosis of an individual patient by a single variable or by a combination of variables. No significant differences were found between the two antibiotic treatment groups.
Acute Disease↗
In vitro and in vivo binding of trimethoprim and sulphachlorpyridazine to equine food and digesta and their stability in caecal contents.
Binding of antibiotics to food has received little attention in equine medicine, although such binding could potentially reduce the bioavailability and clinical efficacy. In the present study, binding of trimethoprim (TMP) and sulphachlorpyridazine (SCP) to hay, grass silage and concentrate was investigated in vitro in buffer at pH 6.8 at different concentrations. The binding of TMP and SCP to caecal contents was also studied. In addition, the degradation of TMP and SCP by the caecal microflora was investigated by incubating sterilized and non-sterilized caecal contents for 3 h at 37 degrees C under anaerobic conditions and comparing the TMP and SCP contents. Further, a TMP/SCP powder formulation was adminstered orally with concentrate at a dose rate of 5 mg/kg TMP and 25 mg/kg SCP to three ponies with a caecum fistula; the animals were deprived of food for 8 h before administration. Blood samples, caecal contents samples and faecal samples were collected and analysed for TMP and SCP concentrations by means of high performance liquid chromatography (HPLC). Three non-fistulated ponies, acting as control animals, were fed the same dose of TMP/SCP with concentrate after 8 h of food deprivation and blood samples were taken. The percentage of in vitro binding of TMP as well as SCP to hay, grass silage and concentrate at concentrations of 4 micrograms/mL to 10 micrograms/mL was high (60-90%). TMP and SCP were also extensively bound to caecal contents (50-70%). At spiking concentrations above 10 micrograms/mL the percentage of binding decreased. There was no evidence of biodegradation of TMP or SCP in caecal contents. In vivo, both drugs could be detected in the caecal contents and in the faeces of three fistulated ponies. However, the fistulated ponies differed from the control ponies in that their TMP and SCP plasma concentrations were higher, and two fistulated ponies did not show double peaks in their plasma concentration-time curves. Therefore, the fistulated ponies did not provide an optimal model for in vivo binding studies. Despite this limitation, it can be concluded that binding of TMP and SCP to food is a major cause of the limited bioavailability of these drugs in the horse. It is hypothesized that the binding is reversible, and that a second absorption phase occurs in the large intestine, but part of the administered dose remains bound as both drugs were found in the faeces.
Administration, Oral↗
Pharmacokinetics and therapeutic potential for repeated oral doses of trimethoprim/sulphachlorpyridazine in horses.
The pharmacokinetic parameters of a powder formulation of trimethoprim/sulphachlorpyridazine were studied in eight healthy horses which received 5 mg/kg trimethoprim and 25 mg/kg sulphachlorpyridazine 12-hourly with concentrate for five days. The intake of the medicated concentrate by the horses was variable during the first two days, but after they became accustomed to the taste the intake by all the horses during the last three days was good. Faecal samples taken before and on the last day of the drug administrations were negative when cultured for salmonella. Compared with the results of a previous single-dose experiment, higher plasma concentrations and a higher area under the curve for both the drugs were observed. The repeated doses provided plasma concentrations above the minimal inhibitory concentration for Streptococcus zooepidemicus, S equi, Actinobacillus equuli and Rhodococcus equi isolated from the respiratory tract of horses. Synergism between the two drugs occurred at different drug concentration ratios with different bacterial species.
Administration, Oral↗
Lipid metabolism in horses with hyperadrenocorticism.
Lipid metabolism was studied in 21 horses with hyperadrenocorticism. To be included in the study, horses had to have histologic evidence of a pars intermedia adenoma found at necropsy (n = 9), a baseline ACTH concentration greater than 400 pg/ml (n = 6), or a plasma cortisol concentration 2 hours after i.v. administration of 25 IU of ACTH greater than 413 nmol/L (n = 16). Mean +/- SD baseline plasma cortisol concentration was 338 +/- 261 nmol/L (n = 20), mean +/- SD plasma insulin concentration was 97 +/- 54 microU/ml (n = 15), mean +/- SD plasma beta-hydroxybutyrate concentration was 1.8 +/- 1.2 mg/dl (n = 21), and mean +/- SD plasma nonesterified fatty acids concentration was 6.2 +/- 6.4 mg/dl (n = 21). None of the horses had hyperlipemia. Compared with clinically normal horses, horses with hyperadrenocorticism had increased lipolysis and increased ketogenesis. It was concluded that cortisol cannot be the sole factor contributing to insulin resistance in horses with hyperadrenocorticism.
3-Hydroxybutyric Acid↗
[Intravenous administration of Ivomec in horses].
Now and then cases have been reported where horses died suddenly after intravenous application of Ivomec. Lethal anaphylactic reactions in horses are known to occur incidentially after intravenous application of drug dissolved in propyleneglycol or glycerolformol. Since Ivomec is registered for use in cattle, sheep and pig, its use in horses has to be regarded as 'off label use'. It is concluded that in the treatment of inhibited stages of cyathostomes ivermectin has no effect whether or not it is applied intravenously or orally. Since lethal anaphylactic reactions can occur, intravenous application of Ivomec can not be justified for 'off label use'.
Anaphylaxis↗
In vitro susceptibility to antimicrobial drugs of 62 Salmonella strains isolated from horses in The Netherlands.
The in vitro activity of 17 antimicrobial drugs against strains of Salmonella typhimurium (n = 52), Salmonella thompson (n = 2), Salmonella heidelberg (n = 3), Salmonella hadar (n = 2), Salmonella enteritidis (n = 1), Salmonella infantis (n = 1) and Salmonella derby (n = 1) was tested using the agar dilution method. The strains were isolated from horses admitted to the Large Animal Clinics of Utrecht University. The majority of strains were susceptible to gentamicin, amikacin, kanamycin, enrofloxacin, ciprofloxacin, flumequine, colistine, furazolidone and ceftiofur. However, all strains of Salmonella typhimurium phage type 200 (n = 14), were multiresistant i.e. were resistant to ampicillin amoxycillin, amoxycillin in combination with clavulanic acid, chloramphenicol, nitrofurantoin, trimethoprim, aditoprim and baquiloprim. Two of these strains were also resistant to gentamicin. Based on the susceptibility data found in the present study in combination with pharmacokinetic data available in the literature a rationale for antimicrobial therapy in equine salmonellosis is given. As first choice, gentamicin at a dosage of 3 mg/kg combined with ampicillin at a dosage of 20 mg/kg given with a 8-12 hour dosing interval by intravenous route is advised. As an alternative, the intravenous administration of trimethoprim/sulfonamide combinations given twice daily at a combined dose of 30 mg/kg is suggested.
Animals↗
Laboratory diagnosis of equine pituitary pars intermedia adenoma.
The objective of the study was to determine the sensitivity with which an adenoma of the pars intermedia of the pituitary gland can be predicted in horses by measuring the basal concentrations of glucose, cortisol, adrenocorticotropin (ACTH), and insulin, the urinary concentration of corticoids, the urinary corticoid:creatinine ratio, and the plasma cortisol concentration after the administration of 25 IU of ACTH intravenously. The records of 24 cases of histologically confirmed equine pituitary pars intermedia adenomas were used. An adenoma of the pars intermedia of the pituitary gland in horses was predicted with a sensitivity of 100, 100, and 92% for basal plasma ACTH (n = 16), the urinary corticoid:creatinine ratio (n = 7), and basal plasma insulin (n = 12), respectively. The sensitivity of the ACTH-stimulation test was 79% (n = 14).
Adenoma↗
Pharmacokinetics of trimethoprim/sulphachlorpyridazine in horses after oral, nasogastric and intravenous administration.
In the present study, the pharmacokinetic parameters of a trimethoprim/sulphachlorpyridazine preparation following intravenous administration, administration by nasogastric tube and administration with concentrate were determined in the horse. Eight adult horses were dosed at 1 week intervals in a sequentially designed study at a dose of 5 mg/kg trimethoprim (TMP) and 25 mg/kg sulphachlorpyridazine (SCP) on all occasions. Plasma concentrations of both drugs were measured serially for 48 h. Pharmacokinetic parameters of clinical importance (distribution and elimination half-lives, clearance, bioavailability, volume of distribution) were determined both for TMP and SCP. Following intravenous administration, the volume of distribution at steady-state (Vd(ss)) was significantly larger for TMP (1.51 +/- 0.25 L/kg than for SCP (0.26 +/- 0.05 L/kg. The clearance was 7.73 +/- 2.26 mL/min.kg for TMP and 2.64 +/- 0.48 mL/min.kg for SCP. For both TMP and SCP, mean peak plasma concentrations (Cmax) and the bioavailabilities (F) were reduced significantly when the drugs were mixed with concentrate (ct) as compared with those after nasogastric administration (ngt) (Fct = 44.3 +/- 10.7% vs. Fngt = 68.3 +/- 12.5% for TMP; Fct = 46.3 +/- 8.9% vs. Fngt = 67.3 +/- 13.7% for SCP). Following the administration of TMP and SCP mixed with concentrate, the plasma concentration-time curves showed a biphasic absorption pattern in all horses. The first peak occurred 1-2 h and the second peak 8-10 h after administration of the combination preparation.(ABSTRACT TRUNCATED AT 250 WORDS)
Absorption↗
Effect of methacholine on mucociliary transport in bovine trachea in vitro.
A method is described to evaluate pharmacologic influence on bovine tracheal mucus transport in vitro. In this model, cholinergic agonist methacholine stimulated transport velocity. Methacholine at concentration of 10(-6)M increased velocity by 13.6%, whereas 10(-5)M increased velocity by 26%. Stimulation was inhibited by atropine.
Analysis of Variance↗