Enteroliths in horses--a retrospective study of 30 cases.

In a retrospective study of selected cases, abdominal colic in 30 horses was attributed to enterolith obstructions of the large intestine. Obstructions caused by "true" enteroliths were confined to horses more than four years old. Prominent clinical features were recurrent mild abdominal pain, inappetance, gaseous distension and minimal intestinal motility. The various aspects of the clinical syndrome, including diagnostic problems and clinical management, are discussed. Most obstructing enteroliths were found near the beginning of the small colon and most horses contained only a single major concretion. Enteroliths were formed by mineral deposition in concentric layers about a central nidus of ingested material and were spherical or tetrahedral in shape. Intestinal concretions were found to consist primarily of ammonium magnesium phosphate.     

Risk factors for enterolithiasis among horses in Texas

OBJECTIVE: To identify risk factors for enterolithiasis in horses. DESIGN: Matched case-control study. ANIMALS: 26 horses with enteroliths, 104 horses with other causes of colic that underwent surgery (52 horses, surgical control group) or were treated medically (52 horses, nonsurgical control group). PROCEDURE: Medical records were reviewed for horses with enteroliths and control horses. Information collected included signalment, anamnesis, and findings on physical examination and clinicopathologic testing at admission. Horses with enteroliths and control horses were compared by means of conditional logistic regression to identify factors associated with enterolithiasis. RESULTS: Horses that were fed alfalfa hay, spent < or = 50% of time outdoors, or were Arabian or miniature breeds had an increased risk of developing enteroliths. Horses with enteroliths were more likely to have been hyperbilirubinemic and to have had clinical signs > 12 hours prior to admission. CONCLUSIONS AND CLINICAL RELEVANCE: Breed and diet appear to influence the risk of enterolithiasis; other management factors also may influence development of enteroliths. Duration of clinical signs may be longer and signs may be less severe among horses with enteroliths, compared with horses with other causes of colic.     

Dietary risk factors and colonic pH and mineral concentrations in horses with enterolithiasis

A prospective, unmatched case control study was performed to identify dietary and environmental risk factors for enterolithiasis in horses in California and to determine whether colonic ingesta analyses differed between horses with and without enteroliths. Forty-three horses with enterolithiasis were compared with 19 horses with surgical colic attributable to nonstrangulating obstruction of the colon without enteroliths. Colonic ingesta samples were collected at surgery from horses with enteroliths and control horses. Colonic pH and colonic concentrations of magnesium, phosphorus, sulfur, sodium, calcium, potassium, and nitrogen were measured. Questionnaires were distributed to owners to determine diet and management practices. Student's t-test and Mann-Whitney tests were used to evaluate differences in pH, dry matter content, percent nitrogen, and mineral content. Associations between dietary and management risk factors and enterolith occurrence were quantified by odds ratios. Mean pH of colonic contents from horses with enterolithiasis was significantly higher than for control horses. Horses with enterolithiasis had significantly lower percent dry matter in colonic fecal samples and higher mean mineral concentrations than controls. On the basis of reported feeding and management practices, horses with enterolithiasis were fed a significantly higher proportion of alfalfa in their diet and were less likely to have daily access to pasture grass than horses without enteroliths. Results suggest that decreasing alfalfa consumption and allowing daily access to pasture grazing might reduce the risk of enterolithiasis. Dietary modifications promoting acidification of colonic contents and dilution of minerals might be beneficial as preventive measures for enterolithiasis in horses.     

Mineral absorption in tapirs (Tapirus spp.) as compared to the domestic horse

To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for tapirs (Tapirus spp.), we investigated the apparent absorption (aA) of macro and micro‐minerals in 18 tapirs from five zoological institutions in a total of 24 feeding trials with total faecal collection. Samples of feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Cu and Zn. The resulting aA coefficients and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content (per 100 g dry matter) were compared with data for domestic horses. While there were no apparent differences in the absorption patterns for P, K, Na, Fe, Cu or Zn, the absorption of both Ca and Mg was distinctively higher in tapirs than in horses. Tapirs are browsers that are adapted to a diet of higher Ca content and higher Ca:P ratio than equids, and high absorptive efficiency for Ca might have evolved to ensure that high dietary Ca concentrations do not lead to the binding of dietary P in the intestine, making it unavailable for hindgut microbes. Similar to other hindgut fermenters, in tapirs, absorption coefficients for Ca increased with dietary Ca:P ratio, and urinary Ca:creatinine ratios increased with dietary Ca. Several zoo diets used were deficient in one or more minerals. When compared with faeces of free‐ranging animals, faeces of zoo animals had higher concentrations of most minerals, probably indicating a lesser diluting effect of indigestible fibre in zoo animals.     

Evaluation of dietary and management risk factors for enterolithiasis among horses in California

Enteroliths are intestinal calculi that result in intestinal obstruction and colic in horses. Equine enterolithiasis occurs worldwide, but the disease is particularly prevalent in some geographic locations, including California. The objectives of this study were to evaluate dietary and environmental risk factors for the disease. This was accomplished through a case–control study by comparing horses with colic from enterolithiasis presenting to the University of California, Davis VMTH, to horses with colic of other causes. Data were collected on 61 horses with enterolithiasis and 75 controls via evaluation of patient records and questionnaires completed by owners at the time of admission. Following multiple logistic regression analysis, the following factors were found to be significantly associated with enterolithiasis: feeding ⩾50% of the diet as alfalfa; feeding <50% of the diet as oat hay; feeding <50% of the diet as grass hay; and lack of daily access to pasture grazing.     

Effects of oral potassium supplementation on acid-base status and plasma ion concentrations of horses during endurance exercise

OBJECTIVE: To compare effects of oral supplementation with an experimental potassium-free sodium-abundant electrolyte mixture (EM-K) with that of oral supplementation with commercial potassium-rich mixtures (EM+K) on acid-base status and plasma ion concentrations in horses during an 80-km endurance ride. ANIMALS: 46 healthy horses. PROCEDURE: Blood samples were collected before the ride; at 21-, 37-, 56-, and 80-km inspection points; and during recovery (ie, 30-minute period after the ride). Consumed electrolytes were recorded. Blood was analyzed for pH, PvCO2, and Hct, and plasma was analyzed for Na+, K+, Cl-, Ca2+, Mg2+, lactate, albumin, phosphate, and total protein concentrations. Plasma concentrations of H+ and HCO3-, the strong ion difference (SID), and osmolarity were calculated. RESULTS: 34 (17 EM-K and 17 EM+K treated) horses finished the ride. Potassium intake was 33 g less and Na+ intake was 36 g greater for EM-K-treated horses, compared with EM+K-treated horses. With increasing distance, plasma osmolarity; H+, Na+, K+, Mg2+, phosphate, lactate, total protein, and albumin concentrations; and PvCO2 and Hct were increased in all horses. Plasma HCO3-, Ca2+, and Cl- concentrations were decreased. Plasma H+ concentration was significantly lower in EM-K-treated horses, compared with EM+K-treated horses. Plasma K+ concentrations at the 80-km inspection point and during recovery were significantly less in EM-K-treated horses, compared with EM+K-treated horses. CONCLUSIONS AND CLINICAL RELEVANCE: Increases in plasma H+ and K+ concentrations in this endurance ride were moderate and unlikely to contribute to signs of muscle fatigue and hyperexcitability in horses.     

Evaluation of dietary and management risk factors for enterolithiasis among horses in California

Enteroliths are intestinal calculi that result in intestinal obstruction and colic in horses. Equine enterolithiasis occurs worldwide, but the disease is particularly prevalent in some geographic locations, including California. The objectives of this study were to evaluate dietary and environmental risk factors for the disease. This was accomplished through a case–control study by comparing horses with colic from enterolithiasis presenting to the University of California, Davis VMTH, to horses with colic of other causes. Data were collected on 61 horses with enterolithiasis and 75 controls via evaluation of patient records and questionnaires completed by owners at the time of admission. Following multiple logistic regression analysis, the following factors were found to be significantly associated with enterolithiasis: feeding 50% of the diet as alfalfa; feeding <50% of the diet as oat hay; feeding <50% of the diet as grass hay; and lack of daily access to pasture grazing.     

Gastric ulceration in horses: 91 cases (1987-1990).

Gastroendoscopy was performed on 111 horses (1 to 22 years old) that had signs of abdominal discomfort of variable duration and severity. At least 1 episode of colic had been observed within 48 hours of examination in 31 horses. Recurrent episodes of colic were observed in 28 horses within 2 to 10 days of examination, 31 horses within 11 to 30 days, 12 horses within 31 to 60 days, and in 9 horses at more than 60 days after the initial examination. Gastric ulceration was found in 91 of 111 horses examined. Other abnormalities involving the gastrointestinal tract or other abdominal viscera were not found on examination in 57 of 91 horses with gastric ulcers. The most frequent concurrent abnormalities found in the remaining 34 horses with gastric ulcers were impaction of the large colon (n = 6), colonic tympany (n = 6), peritonitis (n = 6), gastric impaction (n = 4), ileocecal intussusception (n = 3), small-colon impaction (n = 4), and proximal enteritis (n = 2). Thirteen horses with gastric ulceration underwent abdominal surgery, and in 5 horses, lesions were not found at surgery. Gastric ulceration was determined to be the primary cause of colic in 31 horses on the basis of the lack of other abnormalities, clinical response to treatment with histamine type-2 receptor (H2) antagonists, and confirmation of improvement or resolution of gastric ulceration via endoscopy. Gastric ulceration was the suspected cause of colic in 26 other horses on the basis of the lack of other abnormalities, severity of lesions, and clinical response to treatment with H2 antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mineral Status and Interrelationship in Soil,Forage, and Blood Serum of Horses in the Rainy and Dry Seasons

The objective was to evaluate the content of P, Ca, Mg, K, Na, Cu, Fe, Zn, Se, and Mn in soil, forage, and serum of horses in several production units (PU) during rainy and dry seasons and predict their concentration in serum from their content in soil and forage. Soil and pastures were sampled in the dry (November–December) and in rainy seasons (June–July), and blood samples were collected from the jugular vein of 76 horses in both seasons at four PU. The experimental design was a completely random design within a 4 × 2 (PU × season) factorial arrangement of treatments. Concentration of minerals in soil differed (P < .05) among PU, and contents of P, Ca, Mg, and K were low; Zn and Fe were high; and Cu and Mn were adequate. Mineral concentrations in forage differed among PU and season, and among PU within season (interaction P < .05). Contents of Ca, Mg, Na, Zn, and Cu were low; Fe was high; and P, K, Se, and Mn adequate. The mineral concentration in equine blood serum differed (P < .05) among PU and season. Overall, there were deficiencies of P, Ca, Mg, Na, Cu, and Se, but adequate amounts of K, Zn, and Fe. There are imbalances of minerals in soil and forages which effected their concentration inequine blood.     

Hemostatic abnormalities in equine colic

Hemostatic profiles were determined in 30 horses with clinical colic. Blood samples were obtained at the time of the animal's admission, and the following hemostatic tests were done: blood platelet count, plasma fibrinogen, plasma antithrombin, prothrombin time, partial thromboplastin time, thrombin time, protamine sulfate test for soluble fibrin monomer, and fibrin-fibrinogen degradation products. The patients were categorized in retrospect, according to the cause of the colic: group 1--colic associated with colitis and/or severe diarrhea, group 2--colic associated with torsion or obstruction of the intestine, and group 3--colic associated with impaction of the intestine or the presence of enteroliths. Of the 30 horses with colic, 28 had at least 1 abnormality in their coagulogram--the most frequent abnormalities being high plasma fibrinogen concentration, high circulating soluble fibrin monomer, or a long partial thromboplastin time or thrombin time. The horses in group 1 seemed to have the most severe coagulopathies, as indicated by the average number of demonstrable abnormalities. The horses in group 3 showed the fewest abnormalities--usually a high plasma concentrations of fibrinogen and/or soluble fibrin monomer. The results indicated that hemostatic abnormalities are not uncommon in horses with gastrointestinal disease and colic--the degree of severity depending to some extent on the cause of the colic.     

Abnormal conditions of the equine descending (small) colon: 102 cases (1979-1989).

The signalment, clinical and laboratory findings of surgical conditions, treatment, and outcome of 102 cases of descending colon disease in horses were reviewed. Abnormal conditions were categorized as enteroliths, impactions, strangulating lipomas, fecaliths, foreign body obstruction, volvulus, nephrosplenic entrapment, and other conditions. Eleven breed categories of horses were seen during this period. Arabians, ponies, and American miniature horses were more predisposed to descending colon disease than other breeds (P less than 0.05). Female horses and animals greater than 15 years old were more likely to be affected with descending colon disease, whereas horses less than 5 years old were less likely to be affected (P less than 0.05). More specifically, Arabians, Quarter Horses, and Thoroughbreds greater than 10 years old were breeds that were overrepresented when compared with the hospital population (P less than 0.05). Enteroliths were most commonly seen in horses between 5 and 10 years old (P less than 0.05) and were not seen in horses less than 2 years old. Enteroliths had a tendency to develop more commonly in Arabians and in female horses. Impactions affected horses greater than 15 years old (P less than 0.05) and had a greater tendency to affect ponies and American miniature horses. Female horses were more commonly affected by impaction than were males. Strangulating lipomas were commonly seen in horses greater than 15 years old (P less than 0.05) and more specifically female Quarter Horses (P less than 0.05). Fecaliths tended to be a disease of horses less than 1 year old or greater than 15 years old and affected males more commonly than females.(ABSTRACT TRUNCATED AT 250 WORDS)     

Concentrations of macro- and micro-elements in the milk of pasture-fed thoroughbred mares

OBJECTIVE: To determine the changes in Ca, P, Mg, Na, K, S, Cu, Fe and Zn concentrations of milk during the lactation in pasture-fed Thoroughbred mares and then calculate the dietary mineral requirements of the sucking foal and the lactating mare. PROCEDURE: Milk was sampled on days 1, 3, 7, 14, 21, 28 and at various times between 55 to 65, 85 to 95 and 135 to 150 days after parturition from 21 pasture-fed mares. The concentrations of macro- and micro-elements in the milk were determined by inductively coupled plasma emission spectrometry. RESULTS: Concentrations (mg/L) of these elements were highest in colostrum (Mg 302, Na 561, K 955, S 1035, Cu 0.76, Fe 0.79 and Zn 5.5) except for Ca (1245) and P (895), which where highest on day 7. The mean milk mineral element concentrations (mg/L) over days 55 to 150 were Ca 843, P 543, Mg 47, Na 120, K 590, S 219, Cu 0.19, Fe 0.34 and Zn 2.1. The mean plasma element concentrations (mg/L) over the same period were Ca 120, P 77.1, Mg 17.0, Na 3110, K 168, S 983, Cu 1.1, Fe 1.5 and Zn 0.49. Concentration gradients between plasma and milk were observed and, in the case of Ca, P, Mg, K and Zn, their concentrations in milk were greater than those in plasma, while a reverse situation was observed for Na, S, Cu and Fe. CONCLUSION: With the exception of Ca and P, the highest concentrations of mineral elements were observed in the colostrum. The nursing foal should have access to good pasture or creep feed, because the intakes of Ca, P and Cu from milk may be less than optimum to meet the daily mineral element requirements.     

Clinical assessment and outcome of a single-layer technique for anastomosis of the small intestine in horses

In order to assess postoperative outcome in horses undergoing end-to-end anastomosis of the small intestine, performed using a one-layer technique, 15 horses that underwent exploratory coeliotomy, resection of the small intestine and end-to-end anastomosis using a continuous Lembert pattern were studied. Information on the age, breed, sex, diagnosis, treatment, complications and outcome of each case were obtained from medical records. Follow-up information was obtained via telephone conversations with clients and trainers. Five of the horses had short-term postoperative complications: one had postoperative ileus (POI), colic and peritonitis, one had POI and colic, two had POI only and one had diarrhoea only. A second exploratory coeliotomy was recommended in two of the 15 horses (13 per cent). The short-term survival rate, defined as survival up to the time of discharge from the hospital, was 93.3 per cent (14 of 15 horses). The long-term survival rate, defined as survival for at least 12 months after the surgery, was 84.6 per cent (11 of 13 horses followed up).     

Surgical treatment of colic in American miniature horses: 15 cases (1980-1987).

A study of 15 American miniature horses (AMH) that underwent surgical treatment for colic was performed. Information obtained from the medical records included signalment, clinical signs, type and location of gastrointestinal lesion, and postoperative complications. All 15 AMH had intraluminal obstructions, attributable to feed impactions (11 horses), enteroliths (2), and sand (2). The most common location of obstruction was the small colon, which was involved in 9 of the 15 cases. All 15 AMH survived and were discharged from the hospital. Six of the 15 AMH underwent subsequent surgical treatment for abdominal disorders. Elapsed time between the first and second operations ranged from 1 month to 5 years. Intestinal adhesions were observed in all AMH that were surgically treated twice. Thus, despite the fact that most of the AMH had a simple intraluminal obstruction, 40% (n = 6) developed adhesions that required or complicated a second surgery. Of the 15 AMH, 87% (n = 13) survived at least 12 months after the initial exploratory celiotomy. These findings suggest that most surgical abdominal conditions in AMH can be corrected; however, precautions should be taken to avoid or minimize adhesion formation.     

Mineral absorption in the black rhinoceros (Diceros bicornis) as compared with the domestic horse

To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for black rhinoceroses (Diceros bicornis), we investigated the apparent absorption (aA) of macro- and microminerals in eight black rhinoceroses from three zoological institutions in a total of 32 feeding trials with total faecal collection, with additional data from three unpublished studies (18 feeding trials). Feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Mn, Cu, Zn and Co. The resulting aA coefficients, and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content [per 100 g dry matter (DM)], were compared with data for domestic horses. Rhinoceroses had significantly higher aA coefficients for Ca and Mg (because of a higher calculated 'true' absorption), and lower ones for Na and K (because of calculated higher endogenous faecal losses). High absorption efficiency for divalent cations is hypothesized to be an adaptation to a natural diet of particularly high Ca:P ratio (approximately 14:1); an effective removal of Ca from the ingesta guarantees sufficient P availability at the fermentation site in the hindgut. Higher faecal losses of Na and K are hypothesized to be linked to a higher faecal bulk per DM intake in black rhinoceroses as compared with horses because of a generally lower digestive efficiency. There were no relevant differences in the absorption patterns of microminerals. In particular, there were no discernable differences in Fe absorption within the rhinoceroses for diets with and without tannin supplementation. Several of the zoo diets assessed in this study were deficient in Cu, Mn or Zn, and most contained excessive levels of Fe when compared with horse requirements. The findings of this study indicate that differences in mineral absorption between occur even between species of similar digestive anatomy; that in particular, Ca absorption might vary between hindgut fermenters with Ca:P ratio in their natural diet; that Na might be a particularly limiting factor in the ecology of free-ranging rhinoceroses; that moderate doses of tannins do not seem to markedly influence mineral absorption; and that diets for captive animals should contain adequate, but not excessive mineral levels.     

Content and distribution of macro- and micro-elements in the body of pasture-fed young horses

OBJECTIVE: To determine the content and distribution of Na, K, Ca, P, Mg, S, Cu, Mn, Fe and Zn in the body of pasture-fed young horses and then use a factorial model to calculate the dietary mineral requirements for growth. PROCEDURE: Twenty-one foals were killed at about 150 days of age and the organs, soft tissues, skin and bones and a sample of muscle were dissected out and weighted. The mineral concentrations of elements in all soft tissues and bones were measured by inductively coupled emission spectrometry. The total mineral element composition associated with a tissue was determined from the weight of tissue and its mineral element concentration. RESULTS: Expressed as a percent of total body mineral elements, muscle contained 20% Na, 78% K, 32% Mg, 62% Cu, 36% Mn and 57% Zn, bone contained 47% Na, 99% Ca, 81% P, 62% Mg, 30% Mn and 28% Zn while the organs accounted for a smaller percentage ranging from 0.06% for Ca to 26% for Fe. In liver Cu accounted for 9.2% of total body Cu. Each kilogram of empty body weight was associated with 1.0 g Na, 2.5 g K, 17.1 g Ca, 10.1 g P, 0.4 g Mg, 1.1 mg Cu, 0.39 mg Mn, 52.5 mg Fe and 21.4 mg Zn. CONCLUSION: The mineral element content of body weight gain is a component used in the factorial model to determine dietary mineral element requirements for growth. The calculated dietary mineral requirements, expressed per kg dry matter, for a 200 kg horse gaining 1.0 kg/day were 1.0 g Na, 2.1 g K, 4.6 g Ca, 3.5 g P, 0.7 g Mg, 4.5 mg Cu and 25 mg Zn.     

Plasma arginine vasopressin concentration in horses undergoing surgery for colic

Objective – To determine if horses before undergoing anesthesia for surgical correction of colic would have lower plasma arginine vasopressin (AVP) concentrations than healthy horses undergoing anesthesia for arthroscopic surgery, and would not increase their plasma AVP concentrations in response to anesthesia and surgery. Design – Prospective clinical study. Setting – University teaching hospital. Animals – Fourteen horses with colic and 8 healthy horses. Interventions – Horses with colic underwent anesthesia and surgery for alleviation of colic, and healthy horses underwent anesthesia and surgery for arthroscopy. Measurements and Main Results – Plasma AVP was measured perioperatively in horses with colic and in healthy horses. Before anesthesia, and 30 and 60 minutes after induction, horses with colic had greater median plasma AVP concentrations than control horses (P≤0.001); thereafter during anesthesia differences in AVP concentrations between the 2 groups were not significant. In the control group, plasma AVP concentration increased during 120 minutes of anesthesia; no such increase occurred in colic horses. Conclusions – Compared with healthy horses, horses with colic had higher preanesthesia plasma AVP concentrations that did not increase further in response to anesthesia and surgery. Exogenous AVP is associated with decreased splanchnic perfusion in a variety of animal species and, therefore, could be detrimental to horses with colic. Thus, it may be inappropriate to use exogenous AVP in support of blood pressure in anesthetized horses with colic. Further studies are warranted to define appropriate indications for the use of AVP in horses with colic.     

Determination of lactate concentrations in blood plasma and peritoneal fluid in horses with colic by an Accusport analyzer

BACKGROUND: Intestinal hypoperfusion can lead to increased lactate concentrations in plasma and peritoneal fluid of horses with colic. HYPOTHESIS: The purposes of this study were to (1) evaluate the reliability of the Accusport analyzer to assess peritoneal fluid lactate (PFL) concentrations in healthy horses and those with colic, (2) identify clinical features associated with abnormal blood plasma lactate (BPL) and PFL concentrations, and (3) evaluate the prognostic value of BPL and PFL. ANIMALS: BPL and PFL were determined in 20 healthy horses and in 106 horses with colic. RESULTS: The Accusport was reliable for determining BPL concentrations < 13 mM and PFL concentrations < 20 mM. Multivariate analysis indicated that PCV and the need for intestinal resection were independently associated with the BPL; pulse, PCV, venous pO2, the presence of necrotic intestine, an increased amount of peritoneal fluid, and fluid total protein content were independently associated with PFL. With a 1 mM increase in BPL or PFL, the respective odds ratios for required abdominal surgery increase to 1.23 (BPL) and 1.58 (PFL), odds ratios for a required intestinal resection increase to 1.20 (BPL) and 1.41 (PFL), and odds ratios for developing ileus increase by 1.33 (BPL) and 1.36 (PFL). PFL concentrations of 1, 6, 12, and 16 mM correspond to a probability of death of 11, 29, 63, and 82%, respectively, in horses without strangulating obstruction and of 25, 52, 82, and 92%, respectively, in horses with strangulating obstruction. CONCLUSION: PFL is more useful and sensitive than BPL for prognostic purposes in horses with colic.     

Use of plasma ionized calcium levels and Ca2+ substitution response patterns as prognostic parameters for ileus and survival in colic horses

OBJECTIVE: Hypocalcaemia is a common finding in horses with enterocolitis and severe gastrointestinal disorders. The aims of this study were to investigate in colic horses 1)the parameters related to hypocalcaemia, 2)the influence of hypocalcaemia on outcome and 3)the possible beneficial effect of Ca2+ substitution. DESIGN: Randomized controlled trial. SETTING: Intensive care unit. PATIENTS: One hundred forty-four horses that were admitted with an acute abdomen during a 1.5 year period were enrolled and daily evaluated for clinical criteria and whole blood ionized Ca2+ levels. Colic horses with hypocalcaemia were randomly assigned to receive Ca2+. INTERVENTIONS: Analysis of heparinised whole blood samples. Horses that were assigned to be treated received 400 mEq Ca2+ diluted in 10L of Ringer's lactate solution every 24 h until low reference range limits were obtained or until death. MEASUREMENTS AND MAIN RESULTS: 88% of all colic patients showed blood ionized Ca2+ levels below the reference range at the time of admission. Multivariable analysis revealed that the presence of reflux, signs of endotoxaemia, increased Packed Cell Volume (PCV), alkalinization of pH and the interaction PCV/pH all predispose colic horses to low ionized Ca2+ levels at the time of admission. The Odds for developing ileus during hospitalization are +/- 11.94 times larger for horses in the "very low" calcaemia interval, in comparison with normocalcaemic horses. The Odds for fatal outcome are respectively +/- 9.82 and 8.33 times larger for horses in the "very low" and "low" calcaemia interval. Ca2+ substitution increased the probability of survival, provided that Ca2+ levels could be normalized. The lack of an upward calcaemia response, despite repetitive Ca2+ substitutions, can be guarded as a poor ominous sign. CONCLUSIONS: Hypocalcaemia in colic horses is of prognostic relevance both with regard to survival as to the probability of development of ileus during hospitalization. This study shows the importance of routine measurement of ionized calcium levels in colic horses. Moreover, correction of hypocalcaemia seems to improve clinical outcome.     

不同盐分类型胁迫对豌豆幼苗离子吸收、累积及运输的影响

为了探究不同类型盐分(NaCl、混合Na盐和混合Cl盐)胁迫下3个品种(‘银豌1号’、‘S5001-1’和‘737’)的豌豆幼苗对离子吸收与运输的生理机制,采用水培方法对3个品种的豌豆幼苗的盐分离子吸收、分布、累积特性进行了研究。结果表明,1)3个品种的豌豆幼苗在NaCl和混合Na盐处理下,地上部和根系Na⁺ 含量较对照均显著增加,而K⁺、Ca²⁺含量则显著降低;混合Cl盐处理下,豌豆幼苗地上部和根系Na⁺ 含量较对照均无显著差异,而Cl^-、K⁺、Ca²⁺ 和Mg²⁺含量均显著高于NaCl处理和混合Na盐处理。2)3个品种的豌豆幼苗在正常生长条件下均优先吸收并富集K⁺,其次是Ca²⁺;在NaCl和混合Cl盐处理下优先吸收并富集K⁺,其次是Na⁺ 和Cl^-;混合Na盐处理下则优先吸收并富集Na⁺ 和K⁺,其次是Ca²⁺,但不同处理下离子的分布和累积状况在不同品种的豌豆幼苗间有所不同。3)NaCl和混合Na盐处理下,3个品种的豌豆幼苗的离子选择性吸收系数SA_K,Na、SA_Ca,Na和SA_Mg,Na显著升高,而在混合Cl盐处理下显著降低。同一处理下,3个品种的豌豆幼苗间的离子选择性运输系数也表现不同,NaCl和混合Na盐处理下,‘S5001-1’的ST_K,Na和ST_Ca,Na较对照显著升高,而‘银豌1号’的ST_K,Na和ST_Ca,Na在混合Na盐和混合Cl盐处理下较对照显著降低,3个品种的豌豆幼苗间的ST_K,Na在混合Cl盐处理下无显著差异。以上结果说明,NaCl和混合Na盐处理下,豌豆幼苗地上部对Ca²⁺、K⁺和Mg²⁺的累积量明显下降,同时为了应对盐分胁迫,根系对Ca²⁺、K⁺和Mg²⁺的吸收及运输能力则显著增强;在混合Cl盐处理下,豌豆幼苗地上部对Ca²⁺、K⁺和Mg²⁺的吸收及累积量较其他两种盐分处理明显增加,但根系对于Ca²⁺、K⁺和Mg²⁺的吸收及运输能力则显著低于其他两种盐分处理,而且品种间差异显著。本结果对于阐明不同盐分类型胁迫下植物对离子吸收与运输的生理机制提供一定的理论依据。