Description of 14 cases of bovine hypokalaemia syndrome

Model-based exploration of hypokalemia in dairy cows

Hypokalemia in dairy cows, which is characterized by too low serum potassium levels, is a severe mineral disorder that can be life threatening. In this paper, we explore different originating conditions of hypokalemia-reduced potassium intake, increased excretion, acid-base disturbances, and increased insulin-by using a dynamic mathematical model for potassium balance in non-lactating and lactating cows. The simulations confirm observations described in literature. They illustrate, for example, that changes in dietary intake or excretion highly effect intracellular potassium levels, whereas extracellular levels vary only slightly. Simulations also show that the higher the potassium content in the diet, the more potassium is excreted with urine. Application of the mathematical model assists in experimental planning and therefore contributes to the 3R strategy: reduction, refinement and replacement of animal experiments.

Comparative study on 3 oral potassium formulations for treatment of hypokalemia in dairy cows

BACKGROUND

Hypokalemia is of clinical relevance in cattle. Different mostly empirical treatment options are suggested.

HYPOTHESIS/OBJECTIVES

To evaluate if oral administration of potassium influences the plasma concentration, the intracellular concentration in erythrocytes and in muscle, renal excretion of potassium, and to assess if there are differences in the efficacy of the potassium formulations.

ANIMALS

Thirty cows with hypokalemia (plasma concentration <3.5 mmol/L) were systematically allocated to 3 treatment groups (10 cows/group).

METHODS

The cows received 52 g of potassium in different formulations: group B-potassium chloride bolus (release over 12 hours); group G-potassium propionate gel (release over 2 hours); and group S-potassium chloride solution (immediately available). Potassium concentrations were repeatedly measured in plasma, erythrocytes, muscle, and urine using ICP-OES.

RESULTS

Plasma potassium concentrations for all preparations increased within 30 minutes and the increase lasted for 12 hours. The concentrations of potassium in the erythrocytes and in the muscle, renal potassium excretion, and total urine volume were not affected by administration of any product. There were no differences between the treatments groups. The feed intake increased in 50% of cows within 2 hours after potassium application, which may contribute to the increase of plasma potassium concentration.

CONCLUSIONS AND CLINICAL IMPORTANCE

All the studied potassium formulations are equally effective to treat hypokalemia in dairy cows for over 12 hours but do not influence intracellular concentration or renal excretion of potassium. The plasma potassium concentration should be reevaluated after 12 hours.

Genetic parameters of subclinical macromineral disorders and major clinical diseases in postparturient Holstein cows

The main objective of this study was to assess the genetic parameters of subclinical disorders associated with subclinical hypocalcemia, hypophosphatemia, subclinical hypomagnesemia, hypokalemia, and hyperphosphatemia, as well as major clinical diseases after calving in Holstein cows. The secondary objective was to estimate the associated genetic and phenotypic correlations among these subclinical and clinical conditions after calving in Holstein cows. The study was conducted in 9dairy herds located in Northern Greece. None of the herds used any kind of preventive measures for milk fever (MF). A total of 1,021 Holstein cows with pedigree information were examined from November 2010 until November 2012. The distribution across parities was 466 (parity 1), 242 (parity 2), 165 (parity 3), and 148 (parity 4 and above) cows. All cows were subjected to a detailed clinical examination and blood was sampled on d 1, 2, 4, and 8 after calving. Serum concentrations of Ca, P, Mg, and K were measured in all samples, whereas β-hydroxybutyrate (BHB) was measured only for d 8. The final data set included 4,064 clinical and 16,848 biochemical records (4,020 Ca, 4,019 P, 4,020Mg, 3,792K, and 997 BHB). Data of 1,988 observations of body condition score at d 1 and 8 were also available. All health traits were analyzed with a univariate random regression model. The genetic analysis for macromineral-related disorders included 986 cows with no obvious signs of MF (35 cows with MF were excluded). Analysis for other health traits included all 1,021 cows. A similar single record model was used for the analysis of BHB. Genetic correlations among traits were estimated with a series of bivariate analyses. Statistically significant daily heritabilities of subclinical hypocalcemia (0.13-0.25), hypophosphatemia (0.18-0.33), subclinical hypomagnesemia (0.11-0.38), and hyperphosphatemia (0.14-0.22) were low to moderate, whereas that of hypokalemia was low (0.08-0.10). The heritability of body condition score was 0.20±0.10. Statistically significant daily heritabilities of clinical diseases were those of MF (0.07-0.11), left displaced abomasum (0.19-0.31), and mastitis (0.15-0.41). Results suggest that these health disorders are heritable traits and could be minimized with proper genetic selection. Statistically significant phenotypic correlations were estimated for the first time between macromineral concentrations and almost all transition cow metabolic and infectious health disorders.

Concentration of Potassium in Plasma, Erythrocytes, and Muscle Tissue in Cows with Decreased Feed Intake and Gastrointestinal Ileus

BACKGROUND

Healthy cows consume large amounts of potassium and a sudden loss in appetite can lead to hypokalemia. The routine method to evaluate potassium homeostasis is the measurement of the extracellular potassium in plasma or serum, but this does not provide information about the intracellular potassium pool.

HYPOTHESIS/OBJECTIVES

To evaluate potassium homeostasis by comparing the extracellular and intracellular potassium concentration in cows with reduced feed intake and gastrointestinal ileus.

ANIMALS

Twenty cows 1-3 days postpartum (group 1) and 20 cows with gastrointestinal ileus (group 2).

METHODS

Observational cross-sectional study. Plasma potassium was measured by using an ion-sensitive electrode. Intracellular potassium was measured in erythrocytes and muscle tissue (muscle biopsy) by using inductively coupled plasma optical emission spectroscopy.

RESULTS

Cows of group 1 did not have hypokalemia. Overall cows with gastrointestinal ileus were hypokalemic (mean ± SD, 2.9 mmol/L ± 0.78), but potassium concentration in erythrocytes and muscle tissue was not lower than in postpartum cows. Intracellular potassium in erythrocytes varied very widely; group 1: 3497-10735 mg/kg (5559 ± 2002 mg/kg), group 2: 4139-21678 mg/kg (7473 ± 4034 mg/kg). Potassium in muscle tissue did not differ between group 1 (3356 ± 735 mg/kg wet weight) and group 2 (3407 ± 1069 mg/kg wet weight). No association between extracellular and intracellular potassium concentrations was detected.

CONCLUSIONS AND CLINICAL IMPORTANCE

That measurement of plasma potassium concentration is not sufficient to evaluate potassium metabolism of cows.

Risk factors for the development of hypokalemia in neonatal diarrheic calves

Background

Neonatal diarrheic calves have a clear negative potassium balance because of intestinal losses and decreased milk intake but in the presence of acidemia, they usually show normokalemic or hyperkalemic plasma concentrations.

Objectives

To assess whether marked hypokalemia occurs in response to the correction of acidemia and dehydration and to identify factors that are associated with this condition.

Animals

Eighty‐three calves with a clinical diagnosis of neonatal diarrhea.

Methods

Prospective cohort study. Calves were treated according to a clinical protocol using an oral electrolyte solution and commercially available packages of 8.4% sodium bicarbonate, 0.9% saline and 40% dextrose infusion solutions.

Results

The proportion of hypokalemic calves after 24 hours of treatment (19.3%) was twice as great as it was on admission to the hospital. Plasma K⁺ after 24 hours of treatment was not significantly correlated to venous blood pH values at the same time but positively correlated to venous blood pH values on admission (r = 0.51, P < .001). Base excess on admission (Odds ratio [OR] = 0.81, 95% confidence interval [CI] = 0.70–0.94), duration of diarrhea (OR = 1.37, 95% CI = 1.05–1.80), milk intake during hospitalization (OR = 0.54, 95% CI = 0.37–0.79) and plasma sodium concentrations after 24 hours (OR = 1.12, 95% CI = 1.01–1.25) were identified to be independently associated (P < .05) with a hypokalemic state after 24 hours of treatment.

Conclusions and Clinical Importance

Findings of this study suggest that marked depletion of body potassium stores is evident in diarrheic calves that suffered from marked metabolic acidosis, have a low milk intake and a long history of diarrhea.

Hypokalemia syndrome in cattle

This article describes hypokalemia syndrome. Lactating dairy cows seem to be at the highest risk, but younger animals may also develop the disease. At present, except for animals treated with repeated isoflupredone acetate administration, the exact determinants causing hypokalemia syndrome remain uncertain. Affected animals are anorexic, weak to recumbent, and most often show signs of gastrointestinal stasis. Treatment is directed toward supportive care and oral potassium supplementation.

Efficacy of oral potassium chloride administration in treating lactating dairy cows with experimentally induced hypokalemia, hypochloremia, and alkalemia

Hypokalemia occurs commonly in lactating dairy cows. The objectives of this study were to determine (1) whether a 24-h oral KCl dose of 0.4 g/kg of body weight (BW) was effective and safe in hypokalemic cattle; (2) whether potassium was best administered as 2 large doses or multiple smaller doses over a 24-h period; and (3) the effect of oral KCl administration on plasma Mg concentration and urine Mg excretion in fasted lactating dairy cattle. Plasma K and Cl concentrations were decreased, and blood pH increased, in 15 lactating Holstein-Friesian cows by administering 2 intramuscular (i.m.) 10-mg injections of isoflupredone acetate 24h apart followed by 2 i.m. injections of furosemide (1mg/kg of BW) 8h apart and by decreasing feed intake. Cows were randomly assigned to 1 of 3 treatment groups with 5 cows/group: untreated control (group C); oral administration of KCl at 0.05 g/kg of BW 8 times at 3-h intervals (group K3); and oral administration of KCl at 0.2g/kg of BW twice at 12-h intervals (group K12). A 24-h KCl dose rate of 0.4 g/kg of BW increased plasma and milk K concentration and plasma Cl concentration, and corrected the metabolic alkalosis and alkalemia, with no clinically significant difference between 2 large doses (group K12) or multiple small doses (group K3) of KCl over 24 h. Oral KCl administration decreased peripheral fat mobilization in cattle with experimentally induced hypokalemia, as measured by changes in plasma nonesterified fatty acid concentration, and slightly augmented the fasting-induced decrease in plasma Mg concentration. Our findings support recommendations for a 24-h oral KCl dose of 0.4 g/kg of BW for treating moderately hypokalemic cattle. Additional Mg may need to be administered to inappetant lactating dairy cattle being treated with oral KCl to minimize K-induced decreases in magnesium absorption.

In vitro effects of bethanechol on specimens of intestinal smooth muscle obtained from the duodenum and jejunum of healthy dairy cows

OBJECTIVE

To describe the in vitro effects of bethanechol on contractility of smooth muscle preparations from the small intestines of healthy cows and define the muscarinic receptor subtypes involved in mediating contraction.

SAMPLE POPULATION

Tissue samples from the duodenum and jejunum collected immediately after slaughter of 40 healthy cows.

PROCEDURES

Cumulative concentration-response curves were determined for the muscarinic receptor agonist bethanechol with or without prior incubation with subtype-specific receptor antagonists in an organ bath. Effects of bethanechol and antagonists and the influence of intestinal location on basal tone, maximal amplitude (A(max)), and area under the curve (AUC) were evaluated.

RESULTS

Bethanechol induced a significant, concentration-dependent increase in all preparations and variables. The effect of bethanechol was more pronounced in jejunal than in duodenal samples and in circular than in longitudinal preparations. Significant inhibition of the effects of bethanechol was observed after prior incubation with muscarinic receptor subtype M(3) antagonists (more commonly for basal tone than for A(max) and AUC). The M(2) receptor antagonists partly inhibited the response to bethanechol, especially for basal tone. The M(3) receptor antagonists were generally more potent than the M(2) receptor antagonists. In a protection experiment, an M(3) receptor antagonist was less potent than when used in combination with an M(2) receptor antagonist. Receptor antagonists for M(1) and M(4) did not affect contractility variables.

CONCLUSIONS AND CLINICAL RELEVANCE

Bethanechol acting on muscarinic receptor sub-types M(2) and M(3) may be of clinical use as a prokinetic drug for motility disorders of the duodenum and jejunum in dairy cows.

Effects of dexamethasone and isoflupredone acetate on plasma potassium concentrations and other biochemical measurements in dairy cows in early lactation

OBJECTIVE

To determine whether administration of isoflupredone acetate (ISO) to healthy cows increases the frequency of severe hypokalemia and whether dexamethasone (DEX) has detectable mineralocorticoid properties.

ANIMALS

33 cows at 20 to 25 days of lactation.

PROCEDURES

Cows were randomly allocated to 5 treatment groups and received 2 IM injections (on days 0 and 2) of sterile saline (0.9% NaCl) solution (10 mL each), an injection of ISO (20 mg) or DEX (20 mg) followed by 10 mL of saline solution, or 2 injections of ISO or DEX. Milk production was measured, physical examinations were performed, and blood and urine samples were collected daily on days 0 through 7.

RESULTS

Physical examination parameters did not differ among groups; however, 1 cow developed atrial fibrillation on day 4. Both corticosteroids significantly increased plasma glucose concentrations, and ISO significantly decreased plasma potassium concentrations and increased total carbon dioxide concentrations with time. One dose of ISO decreased mean plasma potassium concentration by 25% on day 2, compared with day 0, and severe hypokalemia (serum potassium concentration < 2.3 mEq/L) developed in 1 of 6 cows. Mean plasma potassium concentration was 46% lower on day 3 than on day 0 in cows receiving 2 doses of ISO, and 5 of 7 cows became severely hypokalemic. Mean urinary fractional excretion of potassium significantly increased from that on day 0 in cows receiving 2 doses of ISO.

CONCLUSIONS AND CLINICAL RELEVANCE

Both corticosteroids had glucocorticoid activity; however, only ISO had mineralocorticoid activity. Compared with saline solution, administration of 2 doses of ISO significantly increased the frequency of severe hypokalemia.

Macromineral disorders of the transition cow

Four macrominerals have the distinction of being involved in the "downer cow" syndrome, which is, unfortunately, often associated with parturition in cows. Inadequate blood calcium (Ca), phosphorus (P), magnesium (Mg), or potassium (K) concentrations can cause a cow to lose the ability to rise to her feet because these minerals are necessary for nerve and muscle function. Less severe disturbances in blood concentrations of these minerals can cause reduced feed intake, poor rumen and intestine motility, poor productivity, and increased susceptibility to other metabolic and infectious disease. Mechanisms for maintaining blood Ca, P, Mg, and K concentrations perform efficiently most of the time, but occasionally these homeostatic mechanisms fail and metabolic diseases such as milk fever occur. Understanding how and why these mechanisms fail may allow the practitioner to develop strategies to avoid these disorders.

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.