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.

[Histochemical changes in skeletal muscles of racehorses susceptible to rhabdomyolysis after exertion. I. Early myopathological changes]. / Histochemische Anderungen in Skeletmuskeln von rhabdomyolyse-empfindlichen Trabrennpferden nach Grenzbelastung. I. Frühzeitige myopathologische Anderungen.

In this communication, the results of an enzyme histochemical study on m. gluteus medius of horses, sensitive to exertional myopathy, during attacks of rhabdomyolysis are presented. The activity and location of about 25 enzymes were examined. In the present report, the early metabolic changes are discussed. Within 6 min after an attack, some large rounded fibres (approximately 2%) were seen, which showed an intense red staining in the haematoxylin and eosin sections. These hypercontracted fibres showed an increase in activity of mitochondrial adenosine triphosphatase, indicating the presence of uncoupling and/or loose coupling of the mitochondria. This finding may point to a deficient production of ATP in the m. gluteus medius of horses sensitive for exertional myopathy and this deficiency may lead to pathological alterations in the skeletal muscles. The pathological fibres revealed a changed activity of other mitochondrial enzymes as well.

[Histochemical changes in skeletal muscles of racehorses susceptible to rhabdomyolysis after exertion. II. Later myopathological and regeneration phenomena]. / Histochemische Anderungen in Skeletmuskeln von rhabdomyolse-empfindlichen Trabrennpferden nach Grenzbelastung. II. Spätere myopathologische und Regenerationserscheinungen.

Needle biopsies from m. gluteus medius of 22 horses which had suffered from repeated attacks of exertional myopathy were studied at various times after an attack, to determine if metabolic alterations can be demonstrated by enzyme histochemistry. Morphological changes and activity of 25 enzymes were studied. Immediately after onset of an attack, some large rounded fibres with a defect of the oxidative phosphorylation were seen. After some hours these fibres lost their glycolytic enzyme activity, followed by disappearance of mitochondrial enzyme activity with accumulation of Ca2+-containing substances. After 16 h inflammatory cells were found in and around necrotic fibres with a strong activity of acid phosphatase and of the 2 oxidative enzymes of the pentose phosphate pathway. The 4th d after onset of the myopathy regenerating fibres could be observed with a strong activity of both NADPH-producing enzymes of the pentose phosphate pathway. The activity of the decarboxylating enzymes NADP+-malate dehydrogenase and NADP+-isocitrate dehydrogenase was increased in these fibres as well. After some month the studied skeletal muscles were completely normal again. Metabolic interpretations based on the histochemical findings are discussed and compared with those given in literature.

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).

Elastic properties of the oesophageal wall in the dynamic measurement of intrathoracic pressure in cattle.

The elastance of the midthoracic portion of the oesophagus was measured in 14 healthy Dutch Friesians. These were divided into three groups with mean ages of six, 126 and 1636 days, respectively. Mean elastance was 0.17, 0.10 and 0.06 kPa ml-1, respectively. The calculated percentage of error, in relating the endoesophageal pressure with that in the thorax, was found to be smaller than 1 per cent for each animal.

Upper airway resistance in healthy Friesian cattle.

Total pulmonary resistance (RL) and upper airway resistance (Ruaw) were measured in nine healthy unsedated Friesian cattle divided into three age groups. Mean values for these three groups of animals aged four, 188 and 1157 days were 0.32, 0.13 and 0.06 kPa litre-1 s for RL; 0.14, 0.09 and 0.05 kPa litre-1 s for Ruaw; and 0.45, 0.68 and 0.79 for the ratio Ruaw/RL respectively. Ruaw, measured with the head in the normal position, did not significantly differ from values obtained with the head in the horizontal position. Ruaw, measured with the head in the vertical position, was approximately three times greater than when measured in the two other positions.

Effects of irradiated sow colostrum on some biochemical and haematological measurements in newborn piglets.

Some biochemical and haematological variables were measured in piglets during the first 48 hours after birth. The piglets were reared either by the sow, or bottle-fed with colostrum (either natural or sterilised by irradiation), or a commercial milk replacer. Mean haemoglobin concentrations, packed cell volumes and erythrocyte counts decreased by approximately 45 per cent in all the groups between birth and 48 hours, but leucocyte counts increased more markedly in the colostrum-fed groups. All the colostrum-fed groups showed rapid increases in serum total protein concentrations which were almost entirely due to increases in gamma globulin concentrations. There was no difference in this respect between natural colostrum and colostrum sterilised by irradiation with 500 Krad of gamma rays. Colostrum sterilised by irradiation can protect piglets against infectious agents and simplify the rearing of piglets under specific pathogen free conditions.

Respiratory syncytial virus pneumonia in Friesian calves: physiological findings.

Clinical, serological and physiological values were measured during and after naturally occurring respiratory syncytial virus pneumonia in four Friesian calves weighing between 120 and 160 kg. Clinical and serological findings were in agreement with the description of spontaneous calf pneumonia, associated with respiratory syncytial virus infection. Pulmonary function values, recorded one, eight, 15 and 57 days after the clinical onset of the disease, provided good evidence that the clinical syndrome associated with respiratory syncytial virus infection in Friesian cattle is at first an acute obstructive disease which is progressively replaced by a moderate subclinical restrictive disease.

Urinary concentration of corticoids in normal horses and horses with hyperadrenocorticism.

The urinary corticoid:creatinine (c:c) ratio was determined in eight horses with hyperadrenocorticism (HAC). The mean (+/- SD) urinary c:c ratio of the eight horses with HAC (29 +/- 14 x 10(-6)) was significantly (P < 0.05) greater than the ratio in seven control horses (11 +/- 4.3 x 10(-6)). The urinary concentration of corticoids in control horses (201 +/- 60.4 nmol litre-1) was significantly (P < 0.05) lower than in horses with HAC (664 +/- 291 nmol litre-1). The urinary creatinine concentrations did not differ significantly (P > 0.05) between both groups. As both false negative and false positive cases were found, it is concluded that a measurement of the urinary c:c ratio in the horse should not be used as the sole test to confirm equine HAC.

Failure of adrenocorticotrophic hormone to release serum amyloid A in cattle.

The objective of this study was to determine whether adrenocorticotrophic hormone plays a direct role in the secretion of serum amyloid A (SAA) in cattle. Seven lactating Holstein-Friesian cows were given either saline or 25 iu adrenocorticotrophic hormone (ACTH) intravenously at 09.00 in a two factor crossover design. Plasma cortisol concentrations had increased significantly by one hour after the injection of ACTH, whereas the SAA level had not increased by 24 hours after injection. It is concluded that in cattle adrenocorticotrophic hormone has no direct influence on the release of SAA by the hepatocyte.

Detection of neurectomy by testing skin sensitivity using an electrical stimulus.

A method for detection of neurectomy by electrical stimulation of the skin, distal to the neurectomy site, was tested for accuracy and feasibility. An electrical stimulation device was designed and tested to find the minimum peak voltage that would elicit a response in normal horses. Twenty seven horses were then tested at regular intervals following neurectomy and their responses recorded. Immediately following neurectomy there was an area of insensitivity with sharply defined borders extending in an arc from the back of the pastern down towards the bulbs of the heels. In the months following neurectomy, re-innervation occurred and this area gradually reduced in size, although it was still possible to detect insensitive areas 14 months after neurectomy in all horses tested. The method proved to be safe, accurate and ethically acceptable.

Enzyme histochemistry on muscle biopsies as an aid in the diagnosis of diseases of the equine neuromuscular system: a study of six cases.

Muscle biopsies from six horses with clinical histories of muscle atrophy, muscle tremors, myopathic symptoms, unsteadiness of pelvic limbs and progressive ataxia were examined. Muscle biopsies were studied with enzyme histochemical techniques to evaluate the diagnostic values of these methods in cases suspected of suffering from neuromuscular disorders. Hypertrophy, atrophy, fibre splitting, waxy degeneration, phagocytosis and necrosis were seen in haematoxylin eosin stained sections of the different cases. Fibre type predominance and fibre type grouping were seen in the calcium ion stimulated myosine ATP-ase (Ca-ATP-ase) stained sections of some cases. 'Moth-eaten fibres' were demonstrated in three cases by staining with NADH: nitro blue tetrazolium oxidoreductase (NADH-TR), succinate dehydrogenase (SDH), NADH dependent malate dehydrogenase, cytochrome c oxidase and by lactate dehydrogenase. The catabolic enzymes, acid phosphatase (ACP) and 5'-nucleotidase were active in cases with fibre phagocytosis. The oxidative part of the pentose phosphate pathway in myopathic tissue seemed to be important in three cases, demonstrated by the increased activity of glucose-6-phosphate dehydrogenase (GPDH) and 6-phosphogluconate dehydrogenase (PGDH). The important feature of diseased horse muscle was that the pathohistochemical changes were exactly the same as in diseased skeletal muscles of humans. The application of tissue saving enzyme histochemical techniques can be recommended in the study of muscle tissue from horses suffering from suspected neuromuscular disorders.

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).

Fat feeding increases equine heparin-released lipoprotein lipase activity.

The aim of this study was to establish the dose-response relationship between fat intake and heparin-released plasma lipoprotein lipase (LPL) activity in horses. Eight mature trotters were fed 4 rations with different fat levels (3.0, 5.0, 7.7, or 10.8% fat in the dry matter) according to a 4 X 4 Latin square design. The experimental rations consisted of hay and different concentrates; the concentrates and hay were given in a 3:1 ratio on an energy basis. Soybean oil was added to the concentrates at the expense of isoenergetic amounts of glucose. Blood samples were taken at the end of each dietary period, which lasted 3 weeks. Fat feeding was found to increase heparin-released plasma LPL activity in a dose-dependent fashion. When the data from this study and previous studies were combined it was calculated that an increase in fat intake by 1 g/kg dry matter is associated with an increase in LPL activity by 0.98 micromol fatty acid released-mL(-1) x h(-1). Fat feeding raised the plasma concentrations of total cholesterol, high-density lipoprotein cholesterol, and phospholipids. Diet did not have a statistically significant effect on plasma triacylglycerol concentrations. The results are discussed in the light of the possible enhancing effect of fat feeding on the oxidative capacity of skeletal muscle.

Relationship between blood hemoglobin, plasma and tissue iron, muscle heme pigment, and carcass color of veal.

In 41 veal calves divided into three groups and fed different levels of dietary iron, blood hemoglobin, plasma iron, liver, spleen, and muscle iron, muscle heme pigment, and carcass muscle color at slaughter were studied. At 45 min postmortem, total carcass color was visually evaluated in the 41 carcasses. In different muscles of the carcasses the color was measured instrumentally using an invasive color measurement method at 45 min postmortem (MCDI score) and a surface color measurement method at 20 h postmortem (Minolta L*, a*, b*, and Chroma scores). Among the three groups, differences (P less than .05) in muscle iron concentrations, muscle heme pigment concentrations, and Minolta a*, b*, and Chroma scores were found. Most striking were the differences in mean iron concentrations in the longissimus thoracis muscles between Groups A (29 micrograms/g DM) and B (44 micrograms/g DM) and in the semimembranosus muscles between Groups A (31 micrograms/g DM) and C (45 micrograms/g DM). The correlations found between Minolta L*, a*, or Chroma score and the iron and heme pigment concentrations in the semimembranosus muscles were high in comparison with those found in the longissimus thoracis and rectus abdominis muscles. Compared with the plasma iron concentration, the blood hemoglobin concentration showed higher correlations with muscle iron and muscle heme pigment concentrations. It can be concluded that different iron concentrations in the milk replacer during the first 7 wk of fattening influence, to some extent, muscle iron and muscle heme pigment at slaughter. However, these differences were not measurable in the overall visual color evaluation of the carcass surface muscles.

Hepatic triacylglycerol synthesis during a period of fatty liver development in sheep.

Fatty liver was induced in six sheep by fasting and treatment with phloridzin and epinephrine. Treatment was associated with a rise in the concentration in serum and hepatic uptake of nonesterified fatty acid (NEFA) compared with pretreatment (P less than .01). At 24 h after the start of the treatment, concentrations of serum lipoprotein in each density class were not different from baseline, but all were elevated (P less than .01) by 120 h of treatment. Hepatic triacylglycerol (TG) concentration increased (P less than .01) 17-fold within the first 48 h of treatment, with no additional increase during the remaining 72 h. The activity of phosphatidate phosphohydrolase (PAP) in hepatic microsomes increased (P less than .01) fourfold over baseline by 48 h of treatment, then declined slightly by 120 h. The activities of diacylglycerol acyltransferase (DGAT) and glycerolphosphate acyltransferase (GPAT) in hepatic microsomes increased during treatment but appeared to follow a slightly different pattern from that of PAP. Activity of GPAT was not above baseline at 48 h, but was at 120 h (P less than .05); DGAT activity was increased (P less than .05) twofold at 48 h, with an apparent continued increase (P less than .01) to threefold over baseline by 120 h of treatment. Fatty liver appeared to develop during a period of rapid hepatic uptake of NEFA without a corresponding increase in serum lipoprotein concentrations. The activities of PAP, GPAT and DGAT, putative regulators of TG synthesis rate, all increased in liver microsomes during a period of high hepatic NEFA uptake, but that of PAP appeared to coincide most closely with the development of fatty liver.

Effects on meat quality of the use of clenbuterol in veal calves.

The objective of this study was to examine the effects of clenbuterol administration on meat quality traits of veal. Sixteen Holstein-Friesian veal calves (male) were randomly assigned to one of four treatment groups; either control (n = 4) or clenbuterol-treated (1.6 micrograms.kg [corrected] BW-1.d-1, 42 d) with a withdrawal period between clenbuterol treatment and slaughter of 8 d (n = 4), 4 d (n = 4), or 2 d (n = 4). All animals were slaughtered at the same day at a commercial slaughterplant. At 30 min postmortem the carcasses were split and the right carcass side was electrically stimulated. After 24 h of cooling the longissimus, semimembranosus, triceps brachii, and psoas major muscles were excised and vacuum-packaged. After 1, 7, and 13 d of vacuum storage at 2 +/- 2 degrees C the muscles were sampled to determine tenderness, water-holding capacity, and color characteristics. Clenbuterol treatment resulted in a slower rate of pH decline in the unstimulated longissimus muscle but did not affect the ultimate pH. Clenbuterol treatment resulted in toughening of the longissimus, semimembranosus, and triceps brachii muscles after 1 and(or) 7 d of storage (P < .05). It is suggested that this resulted from a decrease in postmortem proteolysis because both the intensity of a 30-kDa peptide and the myofibril fragmentation index were lower in clenbuterol-treated muscles. Clenbuterol treatment resulted in increased lightness (L*-value) of longissimus and semimembranosus muscles (P < .05), coincident with a lower water-holding capacity. In a following experiment, the effect of clenbuterol administration (0 [n = 5] and 1.0 [n = 5] mg/kg of feed for 27 d) on calpain and calpastatin levels at 1 d postmortem in longissimus muscles of Friesian Pie Noire veal calves was investigated. Clenbuterol administration resulted in an increase in calpastatin levels (P < .05) and a trend (P < 0.1) toward a decrease in mu-calpain activity at 1 d postmortem.

Abomasal displacement in cattle: influence of concentrates in the ration on fatty acid concentrations in ruminal, abomasal, and duodenal contents.

The primary causative factor in abomasal displacement appears to be atony or hypotony of the abomasum. Seemingly, high-concentrate feeding inhibits abomasal motility by increasing the amount of fatty acids which enter the abomasum. In the present study, cows with ruminal, abomasal, and duodenal fistulas were fed a hay ad libitum ration or a hay and concentration ration and were compared. It was shown that a considerable increase in ruminal volatile free fatty acid (VFFA) concentrations was not followed by a subsequent increase in abomasal VFFA concentrations. Differences in abomasal VFFA levels between the 2 rations could not be found. There was a slight, but insignificant, increase in duodenal VFFA concentrations after cows were fed the hay ration. One cow given the hay and concentrate diet had a small, but significant, increase in duodenal VFFA concentrations during the first 2 hours after feeding. The VFFA concentrations in duodenal fluid were too low to support the hypothesis that changes in duodenal VFFA concentrations could be responsible for abomasal hypotony.

Pulmonary function testing in calves: technical data.

Measurements of airflow (V), tidal volume (Vt), and intrapleural pressure (Ppl) were tested for accuracy in 5 healthy Dutch Friesian calves with an average body weight of 153 kg. A face mask was constructed, using fiberglass and polyester, taking into account the typical facial morphology of the calf. It was tested for airtightness, dead space, laminarity of the expiratory V, and absence of saliva into the pneumotachograph. Three different systems for measuring Ppl (pleura puncturing, esophageal balloon catheter, and esophageal saline solution-filled catheter) were tested in vitro, in a Woulfe's flask, and in vivo, in the 5 calves previously described. Moreover, Ppl measured at 3 different puncture sites of the thorax and at 3 different thoracic positions of the esophagus were compared. The frequency-response was flat to 5 Hz for the intrapleural needle and the balloon catheter, but not for the saline solution-filled catheter. The pulmonary function values obtained by puncture of the pleura at the right 9th intercostal space on a line running from the tuber coxae to the shoulder joint and by the esophageal balloon catheter, the balloon being positioned between the crossing point with the aorta and the 2 largest caudal mediastinal lymph nodes, did not differ significantly. The Ppl changes during normal breathing were greatest in the ventral site of the thorax and in the caudal thoracic portion of the esophagus, less in the dorsal site of the thorax and the middle thoracic portion of the esophagus, and least in the cranial site of the thorax and the cranial thoracic portion of the esophagus.(ABSTRACT TRUNCATED AT 250 WORDS)

Longitudinal study of the effects of lungworm infection on bovine pulmonary function.

Clinical and physiologic investigations were done weekly in 5 nonsedated Friesian calves before, during, and after an induced infection with Dictyocaulus viviparus infective larvae. Clinical, hematologic, serologic, and parasitologic findings were all compatible with the classic picture of moderate subacute verminous bronchitis. Most pulmonary function values revealed significant (P less than or equal to 0.05) changes in the 2nd or 3rd week after inoculation and maximal changes at 5 weeks after inoculation. Most marked changes included a decrease in tidal volume, dynamic lung compliance, and arterial oxygen tension, and an increase in minute ventilation, minute viscous work of breathing, and alveolar-arterial oxygen difference. Minute ventilation, dynamic lung compliance, minute viscous work of breathing, and PaO2 revealed the most homogeneous change. Conversely, maximal change of intrapleural pressure, total pulmonary resistance, and viscous work of breathing had higher variability from week to week.