电解质在反刍动物中的应用

在营养学中,电解质是指在动物代谢过程中稳定不变的阴阳离子,是动物维持正常生长和生产的必需物质,具有重要的生物学功能。在动物体液中,电解质主要参与维持渗透压稳定、调节酸碱平衡和控制水的代谢。生理体液中的电解质平衡是动物正常生理活动的保证,它直接受饲粮中电解质平衡(DCAB)的影响。因此,保持饲粮的电解质平衡对维持动物正常生理过程和生产,发挥动物最大生产潜力以及减轻环境污染都具有重要的现实意义。本文就电解质对反刍动物的生产性能、产品品质、健康状况、矿物质代谢以及其影响因素等进行综述。1　饲料电解质的计算方法饲粮…     

Therapeutic approach to electrolyte emergencies.

Hypokalemia, hyperkalemia, hyponatremia, hypernatremia, hypocalcemia, and hypercalcemia are commonly seen in emergency medicine. Severe abnormalities in any of these electrolytes can cause potentially life-threatening consequences to the patient. It is essential that the clinician understand and correct (if possible) the underlying cause of each disorder and recognize the importance of the rates of correction, especially with serum sodium disorders. The recommended doses in this article might have to be adjusted to the individual patient, and these modifications must be adjusted again to the pathophysiology of the primary underlying disorder.     

Fluid and electrolyte balance in critical patients

Recognition and appropriate management of fluid and electrolyte disorders in critical patients is extremely important. In many cases, these secondary problems are more complicated and more serious than the initiating disease process. A severely ill diabetic patient, for example, is more likely to die from dehydration, hyperosmolality, metabolic acidosis, hypokalemia or hypophosphatemia than from hyperglycemia or lack of insulin therapy. Proper fluid therapy and treatment of electrolyte abnormalities make a major difference in the survival rate of critically ill animals.     

Fluid and electrolyte therapy in ruminants.

Five important questions always must be asked and answered regarding fluid and electrolyte therapy in ruminants: (1) Is therapy needed? (2) What type of therapy? (3) What route of administration? (4) How much should be administered? and (5) How fast should the solution be administered? Food animal veterinarians routinely should carry the following commercially available crystalloid solutions and have the knowledge of how to use the products appropriately: Ringer's solution, 1.3% NaHCO3, acetated Ringer's solution, HS (7.2% NaCl), 8% NaHCO3, 23% calcium gluconate, calcium-magnesium solutions, and 50% dextrose. Ruminants with a blood pH less than 7.20 should be treated intravenously with 1.3% or 8.0% NaHCO3, and those animals with a blood pH greater than 7.45 should be treated intravenously with Ringer's solution. Oral electrolyte solutions or intravenous acetated Ringer's solution should be administered to ruminants with a blood pH greater than 7.20 but less than 7.45, and acetated Ringer's solution is preferred to lactated Ringer's solution. HS solution should be administered whenever rapid resuscitation is required. Oral administration of electrolyte solutions is underused in neonatal and adult ruminants. The optimal solution for oral administration to neonatal ruminants has a sodium concentration between 90 and 130 mmol/L; a potassium concentration between 10 and 20 mmol/L; a chloride concentration between 40 and 80 mmol/L; 40 to 80 mmol/L of metabolizable (nonbicarbonate) base, such as acetate or propionate; and glucose as an energy source. The optimal formulation for adult ruminants is unknown, but such a solution should contain sodium, potassium, calcium, magnesium, phosphate, and propionate to facilitate sodium absorption and to provide an additional source of energy to the animal. Acidemia is treated best by intravenous or oral administration of NaHCO3. Alkalemia is treated best by intravenous administration of Ringer's solution and oral administration of chloride-rich electrolytes such as KCl; the latter provides a physiologically more appropriate treatment than oral administration of vinegar or acetic acid solutions. Hypocalcemia is treated best by administering intravenous calcium borogluconate solutions or oral CaCl2 gels. Hypomagnesemia is treated best by intravenous or subcutaneous administration of combined calcium and magnesium solutions. Hypophosphatemia is treated best by oral administration of feed-grade monosodium phosphate. Hypokalemia is treated best by oral administration of feed-grade KCl; hyperkalemia is treated best by intravenous administration of 8.0% NaHCO3 or HS. The major challenges in treating fluid and electrolyte disorders in ruminants are making treatment protocols more practical and less expensive and formulating an optimal electrolyte solution for oral administration to adult ruminants.     

Therapeutic approach to chronic electrolyte disorders.

Chronic disorders of sodium and potassium occur and occasionally need symptomatic therapy. Hypernatremia primarily indicates loss of free water, whereas hyponatremia may be attributable to various problems. It is important not to correct major aberrations of serum sodium concentrations too quickly lest the therapy be more detrimental than the electrolyte abnormality. In distinction, hypokalemia and hyperkalemia may be corrected quickly. Hypomagnesemia is relatively common, but its clinical significance is still being determined.     

Cardiac arrhythmias and electrolyte disturbances in colic horses

Background

Despite increased focus on cardiac arrhythmias in horses, the nature and prevalence is still poorly described. Case reports suggest that arrhythmias occurring secondary to systemic disease are seen more commonly in the clinic than arrhythmias caused by cardiac disease. The aim of this study was to investigate the prevalence of arrhythmias in colic horses referred for hospital treatment. Associations between electrolyte disturbances and arrhythmias were also investigated.The study population consisted of eight control horses and 22 referred colic horses. A Holter electrocardiography (ECG) was recorded during the first 24 hours of admission. The ECG’s were analysed by a software program followed by manual visual inspection. Arrhythmias registered included second degree atrioventricular (AV) blocks, supraventricular premature complexes (SVPCs), and ventricular premature complexes (VPCs). Blood was collected at admission and again between 12 and 24 hours after ECG was applied, and analysed for concentrations of potassium, sodium, ionised calcium, chloride, glucose, and L-lactate.

Results

Heart rate was 37.4 ± 3.7 bpm in the control group, and 51.6 ± 11.8 bpm, in the colic group, which was significantly different (P < 0.0001). AV blocks and SVPCs were found in both groups, however only colic horses showed VPCs. No significant difference between the two groups was found for AV blocks, SVPCs, and VPCs (P = 0.08 - 0.76). The mean levels of potassium, sodium, ionized calcium, and chloride were significantly lower in the colic group compared to the control group at admission. Mean levels of glucose and L-lactate were significantly elevated in the colic group (P < 0.05).

Conclusions

This study describes prevalence of cardiac arrhythmias and electrolytes concentrations in colic horses compared to healthy controls. Although we only observed VPCs in the colic horses, no significant differences between colic horses and controls were found. Despite the colic horses having electrolyte changes at admission no correlation was found between the electrolyte disturbances and cardiac arrhythmias. Although no clear conclusions can be drawn from the present study, the results indicate that relatively mild colic per se is not pro-arrhythmogenic, whereas severe colic probably are more likely to result in ventricular arrhythmia.     

日粮电解质平衡在动物营养中的研究应用

讨论电解质平衡对动物生产性能、动物健康、营养物质代谢产生的影响及添加酸化剂对体内酸碱平衡和日粮电解质的影响。     

Abnormalities of serum electrolyte concentrations in dogs with hypoadrenocorticism

BACKGROUND: The sensitivity and specificity of the sodium to potassium ratio (Na:K ratio) as a cutoff for recommendation of an adrenocorticotropic hormone (ACTH) stimulation test in dogs suspected of having hypoadrenocorticism (HA) is unknown. Additionally, abnormalities in plasma ionized calcium (iCa2+) and ionized magnesium (iMg2+) concentrations and venous pH of dogs with HA are incompletely documented. OBJECTIVES: To define the sensitivity and specificity of the Na:K ratio as a diagnostic aid for HA in dogs and to examine for associations between venous pH and the Na:K ratio, iCa2+ concentration, or iMg2+ concentration in dogs with HA. ANIMALS: Seventy-six dogs with HA and 200 dogs randomly selected from the general hospital population. METHODS: Retrospective study. Dogs were included in the study if results of an ACTH stimulation test confirmed a diagnosis of HA, the dog had a serum sodium concentration below the reference range or a serum potassium concentration above the reference range, and the dog was treated with mineralocorticoids. Receiver operating curve analysis was used to determine optimal cutoffs of sensitivity and specificity for the Na:K ratio in diagnosing HA. RESULTS: Use of Na:K ratios of 27 or 28 classified 95% of dogs correctly as diseased or not diseased. The sensitivity of a Na:K ratio of 28 was 93% (CI, 85-98%) and that of 27 was 89% (CI, 80-95%). The specificity of a Na:K ratio of 28 was 96% (CI, 92-98%) and that of 27 was 97% (CI, 93- 99%). The sensitivity and specificity of a Na:K ratio of 24 were 79% (95% CI, 67-86%) and 100% (98%, CI, 97%-100%), respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Na:K ratios of 27 or 28 identify the highest percentage of dogs with suspected mineralocorticoid and glucocorticoid deficiency correctly. In dogs with a Na:K ratio of 24 or less, the likelihood of confirming a diagnosis of HA with an ACTH stimulation test is high.     

饲粮电解质平衡在动物营养中的重要性

在营养学中，电解质指那些在代谢过程中稳定不变的阴阳离子。生理体液中的电解质主要参与维持渗透压、调节酸碱平衡和控制水的代谢。生理体液中的电解质平衡对于动物的正常生理活动是十分重要的。由于生理体液中的电解质平衡直接受饲粮电解质平衡的影响，因此饲粮电解质平衡可影响动物的代谢过程。本文着重阐述饲粮电解质平衡对营养物质代谢、动物健康和生产性能的影响。１饲粮电解质平衡的表示方法动物饲粮主要电解质的平衡（ｄＥＢ），可表示为各离子毫摩尔数与其化合价（电荷数）乘积（ｍＥｑ）的总和，即ｄＥＢ（ｍＥｑ）＝（Ｎａ＋＋Ｋ…     

Metabolic and electrolyte disturbances in acute canine babesiosis.

Arterial blood pH, PCO2, bicarbonate, base excess/deficit, and lactate, as well as serum sodium, potassium, and chloride were measured in clinically normal dogs and in dogs with acute canine babesiosis. Metabolic acidosis developed in dogs with fatal as well as nonfatal Babesia canis infection. In the fatal group, the acidosis was uncompensated; among survivors, base deficit and blood lactate were significantly lower, and pH, PCO2, and bicarbonate values were significantly higher. Serum potassium values were significantly lower, and serum chloride values were significantly higher in dogs with acute babesiosis than in clinically normal dogs. The shock resulting from acute canine babesiosis is best viewed as anemic shock. Treatment should include an alkalizing agent, a blood transfusion, fluid therapy, and a babesicidal drug.     

Managing fluid and electrolyte disorders in renal failure.

Because of the role of the kidneys in maintaining homeostasis in the body, kidney failure leads to derangements of fluid, electrolyte, and acid-base balance. The most effective therapy of a uremic crisis is careful management of fluid balance, which involves thoughtful assessment of hydration, a fluid treatment plan personalized for the specific patient, repeated and frequent reassessment of fluid and electrolyte balance, and appropriate changes in the treatment plan in response to the rapidly changing clinical situation of the patient that has renal failure. Disorders of sodium, chloride, potassium, calcium, and phosphorus are commonly encountered in renal failure and may be life threatening. Treatment of metabolic acidosis and nutritional support are frequently needed.     

Renal regulation of electrolyte and acid-base balance in ruminants

The kidney maintains volume, electrolyte, and acid-base homeostasis. These functions are examined in the ruminant in response to differing dietary intakes and disease states. The consequences of renal disease for these homeostatic processes and the interpretation of urinary excretion data are reviewed.     

家禽日粮电解质平衡研究进展

矿物元素在动物营养中处于重要地位。通过国内外众多学者的研究，人们已对多种矿物质元素，如常量元素钙、磷、钠、钾、氯等功能特性有了比较系统的了解，但对日粮不同矿物质离子的互作平衡间的研究还有待于进一步的发展和探索。     

Furosemide-induced electrolyte depletion associated with echinocytosis in horses.

Echinocytes have been incriminated in the pathogenesis of exertional diseases in horses. To evaluate the hypothesis that echinocytes are dehydrated erythrocytes, we decreased blood sodium and potassium concentrations in 4 horses by administering furosemide (1.0 mg/kg of body weight, q 12 h) for 2 days and we monitored CBC, serum and erythrocyte sodium and potassium concentrations, and echinocyte numbers. Serum sodium concentration decreased progressively over the 48 hours of furosemide administration, then returned to near baseline concentration at 168 hours. A statistically significant decrease (P < 0.05) in serum potassium concentration was observed at 24, 48, and 72 hours after initial furosemide administration, and remained less than the baseline value at the end of the study. Mean erythrocyte potassium concentration decreased rapidly and remained low at the end of the study. Minimal changes were observed in erythrocyte sodium concentration during the first 72 hours after furosemide administration, but the value was significantly (P < 0.05) increased at 168 hours. Type-I and type-II echinocyte numbers increased by 4 hours after furosemide administration and persisted throughout the study. Type-III echinocytes were not seen in baseline samples, but numbers increased only modestly after furosemide administration. Administration of epinephrine to well-hydrated horses increased echinocyte numbers only minimally, indicating that splenic contraction was not the likely cause for the furosemide-associated increase. To determine whether the decrease in erythrocyte potassium concentration and increase in sodium concentration was caused by furosemide acting directly on the erythrocyte membrane, we quantified erythrocyte potassium and sodium concentrations before and after incubation with furosemide in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)