Treatment of sodium balance disorders. Water intoxication and salt toxicity

Blood chloride abnormalities in diarrheic neonatal calves with metabolic acidosis

The present study investigated the prevalence of blood chloride (Cl) abnormalities in diarrheic neonatal calves with metabolic acidosis and attempted to identify the most relevant electrolyte abnormality to these abnormalities. A retrospective analysis was conducted on the medical records of 157 diarrheic neonatal calves aged 10.3 ± 4.2 days old with metabolic acidosis. Hypochloremia, normochloremia, and hyperchloremia were observed in 8.9% (14/157), 43.3% (68/157), and 47.8% (68/157), respectively, of diarrheic calves with metabolic acidosis. This distribution remained similar regardless of age (under 8 days or 8 days and older). Furthermore, a multiple logistic regression analysis showed that variations in values for blood sodium [Na (regression coefficients 0.877; 95% confidence interval (CI) 13.977-134.195; P<0.01)], pH (regression coefficients -10.719; 95% CI -19.076- -2.362; P<0.05), and bicarbonate [HCO3- (regression coefficients -0.555; 95% CI -0.820- -0.290; P<0.01)] were associated with blood Cl abnormalities. The present results revealed that blood Na concentrations were more strongly associated with blood Cl concentrations than blood pH and HCO3- values. In the present study, diarrheic calves with hyperchloremia were characterized by normonatremia and extremely severe metabolic acidosis.

Sodium distribution in the bovine brain

Fatal sodium intoxication can occur in many species, including cattle, and postmortem confirmation often includes brain sodium concentration determination. Published information regarding brain sodium distribution in cattle was not found in a literature review. Our study was designed to determine whether sodium is uniformly distributed throughout the bovine brain. Eight whole bovine brains were collected from adult cattle with no neurologic signs or history suggestive of sodium intoxication, and with a non-neurologic cause of death diagnosed on gross examination. Brains were divided mid-sagittally. One hemisphere of each brain was homogenized. Subsamples were obtained from the remaining hemisphere (rostral, caudal, and dorsal cerebral cortices; brainstem, thalamus, and cerebellum). Sodium concentrations of regions and homogenates were measured by inductively coupled plasma-mass spectrometry. Data were analyzed using repeated measures ANOVA with a pairwise post-test to compare mean sodium concentration of each region to mean homogenate sodium concentration. Brain sodium was not uniformly distributed; sodium concentrations in different regions of the same brain varied somewhat unpredictably. Homogenization of an entire brain hemisphere appears to be the ideal method of sample preparation to ensure accurate brain sodium concentration measurement in adult cattle.

Clinical application of 2.16% hypertonic saline solution to correct the blood sodium concentration in diarrheic calves with hyponatremia

The aim of this study was to examine whether 2.16% hypertonic saline solution (HSS) is useful for the treatment of diarrheic calves with hyponatremia. Eleven of 13 female Holstein calves exhibiting moderate diarrhea and hyponatremia received 1,250 ml of 2.16% HSS over 15 min regardless of body weight. The remaining two calves that were unable to stand and had severe hyponatremia received 2,500 ml of 2.16% HSS intravenously over 30 min. As a result, hyponatremia in all diarrheic calves was significantly improved by the administration of 2.16% HSS from 122.2 ± 7.0 mEq/l at pre to 134.8 ± 3.7 mEq/l at post, which was above the threshold of 132 mEq/l for hyponatremia. Therefore, 2.16% HSS may be useful for hyponatremia in calves with diarrhea.

Grasping at straws: a re-evaluation of sweepstakes colonisation of islands by mammals

Natural rafting is an easy, non-evidence-based solution often used to explain the presence of a variety of species on isolated islands. The question arises as to whether this solution is based on solid scientific grounds. It is a plausible colonisation route only if intricate networks of variables are considered and many different conditions satisfied. This review provides a descriptive account of some of the most critical issues underlying the theory of natural rafting that should be addressed by its supporters. These include: (i) biological variables; (ii) characteristics of the vessels; and (iii) physical variables. Natural rafting may explain the dispersal of poikilotherms with low metabolic rates and low resource requirements that could withstand trans-oceanic crossings, but explaining the transport of homeothermic terrestrial mammals to oceanic islands is more problematic. Drifting at sea exposes organisms to high concentrations of salt, high temperature and humidity excursions, starvation, and above all to dehydration. A sufficiently large group of healthy reproductive individuals of the two sexes should either be transported together, or be able to reassemble after separate crossings, to prevent inbreeding, genetic drift and ultimately extinction. Any vessels of flotsam occupied must minimally provide the animals they transport with sufficient provisions to survive the journey, offer minimum friction and drag through water, and be transported by appropriately directed, sustained, high-speed currents. Thus, a 'sweepstakes colonisation' event would be the result of a lucky combination of all, or at least the majority, of these factors. Some cases throw doubt on the use of a natural rafting model to explain known animal colonisations, with one of the most striking examples being Madagascar. This island is far from the nearest mainland coasts and the sea currents in the Mozambique Channel are directed towards Africa rather than Madagascar, yet, the island was colonised by terrestrial mammals (e.g. extinct hippopotamuses, lemurs, carnivores, rodents and tenrecs) unable to swim and to survive long journeys at sea. In order to assess the feasibility of the natural rafting model in a case such as Madagascar, tests were performed using three variables for which enough information could be obtained from the literature: length of survival without food, survival without water, and sea current speed. The distributions of these variables appear to be log-normal and multiplicative, or follow a power-law, rather than being Gaussian. The tests suggest that a distributional analysis is a more suitable approach than the use of geometric probability to calculate the probabilities associated with the examined data. Such non-linear and self-organising systems may reach a critical point governed by different competing factors. Mammals with high survival requirements, such as lemurs and hippopotamuses, thus may have a virtually zero probability of reaching distant islands by natural rafting. Our results raise doubts as to the validity of a natural rafting model, and we urge a rethinking of the modes in which numerous islands were colonised by land mammals and a careful revision of past geological and phylogeographic work.

Toxicoses of the Ruminant Nervous System

This article discusses the etiology, mechanism of action, clinical signs, and diagnostic tests used to identify toxic agents that affect the nervous system of ruminants. The article is not intended to be an exhaustive review of each agent, but a reference for establishing a differential diagnosis when toxic agents are suspected as the cause of central nervous system disease in ruminants. The initial focus of the article is on agents that cause brain lesions consistent with polioencephalomalacia. Other neurotoxic disease agents include bovine bonkers, urea, organophosphate, organochlorine, cyanobacteria, zinc, aluminum, phosphide, metaldehyde, strychnine, botulism, tetanus, clostridium perfringens, and poisonous plants.

Clinical efficacy of intravenous hypertonic saline solution or hypertonic bicarbonate solution in the treatment of inappetent calves with neonatal diarrhea

Background: The clinical efficacy of IV administered hypertonic saline solution and hypertonic bicarbonate solution (HBS) in the treatment of inappetent diarrheic calves has not been compared yet.

Hypothesis: HBS is more advantageous than hypertonic saline in the treatment of calves with severe metabolic acidosis.

Animals: Twenty‐eight dehydrated, inappetent calves with neonatal diarrhea.

Methods: In 2 consecutive clinical studies, calves were initially treated with saline (5.85%; 5 mL/kg body weight [BW] over 4 minutes; study I: N = 16) or bicarbonate solution (8.4%; 10 mL/kg BW over 8 minutes; study II: N = 12), respectively, followed by oral administration of 3 L isotonic electrolyte solution 5 minutes after injection. Clinical and laboratory variables were monitored for 72 hours.

Results: Treatment failed in 6 calves of study I and in 1 calf of study II as indicated by a deterioration of the general condition. All treatment failures had more severe metabolic acidosis compared with successfully treated calves before treatment. In the latter, rehydration was completed within 18 hours after injection; metabolic acidosis was corrected within 24 hours (study I) and 6 hours (study II) after injection.

Conclusions and Clinical Importance: Diarrheic calves with slight metabolic acidosis (base excess [BE] >−10 mM) can be treated successfully with hypertonic saline. HBS is appropriate in calves without respiratory problems with more severe metabolic acidosis (BE up to −20 mM). Intensive care of the calves is required to ensure a sufficient oral fluid intake after the initial IV treatment.