Myelinolysis after correction of hyponatremia in two dogs

Suspected paraneoplastic syndrome of inappropriate antidiuretic hormone secretion associated with a gastric adenocarcinoma in a dog

This report describes a suspected case of paraneoplastic syndrome of inappropriate antidiuretic hormone (SIADH) in a 5-year-old male entire Australian Kelpie associated with a gastric adenocarcinoma. The dog had a history of chronic vomiting and presented with hyponatraemia, hypokalaemia, hypochloraemia and increased urinary sodium. Computed tomography identified the presence of a gastric tumour and histopathology confirmed a pyloric gastric adenocarcinoma. Removal of the tumour via a Billroth I procedure resulted in rapid resolution of electrolyte derangements. The dog was still alive six months postoperatively with no recurrence of either SIADH or tumour at the time of publication.

Prolonged extracellular low sodium concentrations and subsequent their rapid correction modulate nitric oxide production dependent on NFAT5 in microglia

Hyponatremia is the most common clinical electrolyte disorder. Chronic hyponatremia has been recently reported to be associated with falls, fracture, osteoporosis, neurocognitive impairment, and mental manifestations. In the treatment of chronic hyponatremia, overly rapid correction of hyponatremia can cause osmotic demyelination syndrome (ODS), a central demyelinating disease that is also associated with neurological morbidity and mortality. Using a rat model, we have previously shown that microglia play a critical role in the pathogenesis of ODS. However, the direct effect of rapid correction of hyponatremia on microglia is unknown. Furthermore, the effect of chronic hyponatremia on microglia remains elusive. Using microglial cell lines BV-2 and 6-3, we show here that low extracellular sodium concentrations (36 mmol/L decrease; LS) suppress Nos2 mRNA expression and nitric oxide (NO) production of microglia. On rapid correction of low sodium concentrations, NO production was significantly increased in both cells, suggesting that acute correction of hyponatremia partly directly contributes to increased Nos2 mRNA expression and NO release in ODS pathophysiology. LS also suppressed expression and nuclear translocation of nuclear factor of activated T cells-5 (NFAT5), a transcription factor that regulates the expression of genes involved in osmotic stress. Furthermore, overexpression of NFAT5 significantly increased Nos2 mRNA expression and NO production in BV-2 cells. Expressions of Nos2 and Nfat5 mRNA were also modulated in microglia isolated from cerebral cortex in chronic hyponatremia model mice. These data indicate that LS modulates microglial NO production dependent on NFAT5 and suggest that microglia contribute to hyponatremia-induced neuronal dysfunctions.

Magnetic resonance imaging pattern recognition of metabolic and neurodegenerative encephalopathies in dogs and cats

Metabolic/neurodegenerative encephalopathies encompass a wide list of conditions that share similar clinical and magnetic resonance imaging (MRI) characteristics, challenging the diagnostic process and resulting in numerous tests performed in order to reach a definitive diagnosis. The aims of this multicentric, retrospective and descriptive study are: (I) to describe the MRI features of dogs and cats with metabolic/neurodegenerative encephalopathies; (II) to attempt an MRI recognition pattern classifying these conditions according to the involvement of grey matter, white matter or both; and (III) to correlate the MRI findings with previous literature. A total of 100 cases were recruited, comprising 81 dogs and 19 cats. These included hepatic encephalopathy (20 dogs and three cats), myelinolysis (five dogs), intoxications (seven dogs and one cat), thiamine deficiency (two dogs and seven cats), hypertensive encephalopathy (three dogs and two cats), neuronal ceroid lipofuscinosis (11 dogs and one cat), gangliosidosis (three dogs and two cats), fucosidosis (one dog), L-2-hydroxyglutaric aciduria (13 dogs and one cat), Lafora disease (11 dogs), spongiform leukoencephalomyelopathy (one dog) and cerebellar cortical degeneration (four dogs and two cats). None of the hepatic encephalopathies showed the previously described T1-weighted hyperintensity of the lentiform nuclei. Instead, there was involvement of the cerebellar nuclei (8/23), which is a feature not previously described. Dogs with myelinolysis showed novel involvement of a specific white matter structure, the superior longitudinal fasciculus (5/5). Thiamine deficiency affected numerous deep grey nuclei with novel involvement of the oculomotor nuclei (3/9), thalamic nuclei, subthalamus and cerebellar nuclei (1/9). Cats with hypertensive encephalopathy had a more extensive distribution of the white matter changes when compared to dogs, extending from the parietal and occipital lobes into the frontal lobes with associated mass effect and increased brain volume. Lysosomal storage disease showed white matter involvement only, with neuronal ceroid lipofuscinosis characterised by severe brain atrophy when compared to gangliosidosis and fucosidosis. All patients with L-2-hydroxyglutaric aciduria had a characteristic T2-weighted hyperintense swelling of the cerebral and cerebellar cortical grey matter, resulting in increased brain volume. Lafora disease cases showed either normal brain morphology (5/11) or mild brain atrophy (6/11). Dogs with cerebellar cortical degeneration had more marked cerebellar atrophy when compared to cats. This study shows the important role of MRI in distinguishing different metabolic/neurodegenerative encephalopathies according to specific imaging characteristics.

2024 AAHA Fluid Therapy Guidelines for Dogs and Cats

Fluids are drugs used in veterinary patients capable of producing beneficial therapeutic or inadvertent harmful effects within the body's intravascular, interstitial, and intracellular fluid spaces. The individualized design of a fluid therapy plan requires careful patient assessment and targeted selection of proper fluid types, administration routes, and rates, along with adjustments during therapy tailored specifically as per the individual patient's fluid requirement and therapeutic response. Personalized fluid prescriptions and vigilant patient monitoring help avoid patient morbidity from body fluid deficiencies, fluid excess, and electrolyte derangements and support better patient outcomes. These guidelines provide an overview of fluid dynamics within the fluid spaces of the body, describe various types of fluids and their uses, and outline recommendations for fluid administration for resuscitation, rehydration, and maintenance purposes. The guidelines also outline approaches to fluid therapy for anesthetized patients and reiterate the recommendations of reduced fluid rates in this population of patients. Additionally, the guidelines include practical fluid therapy strategies for patients with various common disorders. The goal of these guidelines is to help veterinary professionals safely and effectively prescribe and administer fluid therapy for canine and feline patients.

Loss of Ephaptic Contacts in the Murine Thalamus during Osmotic Demyelination Syndrome

BACKGROUND AND AIM

A murine model mimicking osmotic demyelination syndrome (ODS) revealed with histology in the relay posterolateral (VPL) and ventral posteromedial (VPM) thalamic nuclei adjoined nerve cell bodies in chronic hyponatremia, amongst the damaged 12 h and 48 h after reinstatement of osmolality. This report aims to verify and complement with ultrastructure other neurophysiology, immunohistochemistry, and molecular biochemistry data to assess the connexin-36 protein, as part of those hinted close contacts.This ODS investigation included four groups of mice: Sham (NN; n = 13), hyponatremic (HN; n = 11), those sacrificed 12 h after a fast restoration of normal natremia (ODS12h; n = 6) and mice sacrificed 48 h afterward, or ODS48 h (n = 9). Out of these, thalamic zones samples included NN (n = 2), HN (n = 2), ODS12h (n = 3) and ODS48h (n = 3).

RESULTS

Ultrastructure illustrated junctions between nerve cell bodies that were immunolabeled with connexin36 (Cx36) with light microscopy and Western blots. These cell's junctions were reminiscent of low resistance junctions characterized in other regions of the CNS with electrophysiology. Contiguous neurons showed neurolemma contacts in intact and damaged tissues according to their location in the ODS zones, at 12 h and 48 h post correction along with other demyelinating alterations. Neurons and ephaptic contact measurements indicated the highest alterations, including nerve cell necrosis in the ODS epicenter and damages decreased toward the outskirts of the demyelinated zone.

CONCLUSION

Ephapses contained C × 36between intact or ODS injured neurons in the thalamus appeared to be resilient beyond the core degraded tissue injuries. These could maintain intercellular ionic and metabolite exchanges between these lesser injured regions and, thus, would partake to some brain plasticity repairs.

Case report: Recovery and sequential imaging of a patient with osmotic demyelination syndrome

A 4-year-old neutered-male Australian Shepherd was presented to an emergency and referral hospital for an acute onset of neurologic signs and abnormal mentation. Seven days prior, the patient had been diagnosed with hypoadrenocorticism and was treated accordingly at another hospital. Based on recent clinical history, the neurologic signs were consistent with thalamic and brainstem deficits and suspected to be caused by osmotic demyelination syndrome secondary to rapid correction of hyponatremia. A brain MRI confirmed lesions consistent with osmotic demyelination syndrome. The patient's clinical signs initially worsened, and he required intensive nursing care with multimodal sedation, close monitoring of electrolytes and tailored fluid therapy. The patient recovered and was discharged on day seven of hospitalization. Four and a half months later, re-evaluation of the patient showed complete resolution of the neurological deficits with a now unremarkable neurological exam, and follow-up MRI revealed still present, yet improved bilateral thalamic lesions. This is the first known veterinary case report of sequential brain imaging of a dog that has recovered from osmotic demyelination syndrome. In humans, patients can have evidence of near to full clinical recovery, yet imaging findings may still be abnormal several months after recovery. This report details similar imaging findings in a canine with improved clinical signs, despite persistent lesions on brain MRI. Prognosis of canines with osmotic demyelination syndrome may be better than previously perceived, despite the severity of clinical signs and brain lesions apparent on MRI.

Case Report: Hindlimb Ataxia Concurrent With Seizures by Presumed Osmotic Demyelination Syndrome in a Dog

A 6-year-old castrated male Chihuahua dog was presented with hindlimb paresis and ataxia. The dog had hyponatremia and was diagnosed as hypoadrenocorticism 10 days before its visit, and the neurologic signs including generalized tonic seizures and hindlimb paresis occurred 3 days after correction of hyponatremia at a referral hospital. Based on history and clinical findings, osmotic demyelination syndrome (ODS) secondary to rapid correction of hyponatremia was highly suspected. After administration of anti-convulsant and supplements, seizures did not occur, and gait was normalized within 2 weeks. Phenobarbital was tapered and finally discontinued after 3 months, and seizure did not recur. The neurologic signs were completely resolved and the dog continued to be free of neurologic or additional clinical signs over the 19-month follow-up period. ODS should be included among the differential diagnoses in case of any acute neurological dysfunction that occurs with episodes of rapid correction of hyponatremia. To the author's knowledge, this is the rare case report of a dog with hypoadrenocorticism and presumed ODS after rapid correction of hyponatremia leading to neurologic signs including seizures and ataxia.

Central pontine myelinolysis secondary to rapid correction of hyponatremia historical perspective with Doctor Robert Laureno

OBJECTIVES

Central pontine myelinolysis (CPM) is a neurological disorder characterized by damage to the myelin and oligodendrocytes in the pons. This review focuses on the history of CPM and the discovery of its association with the treatment of hyponatremia.

METHODS

The author reviewed original publications regarding CPM, hyponatremia, and the treatment of hyponatremia. The author interviewed Dr. Robert Laureno who was a pioneer in CPM research with his animal work in dogs.

RESULTS

Animal models demonstrated the role of the rapid correction of hyponatremia as causative of pontine and extrapontine myelinolytic lesions. Nevertheless, the importance of the speed of correction was widely denied. There were years of debates and only slow changes in expert guidelines.

CONCLUSION

CPM occurs as a consequence of a rapid rise in serum sodium in individuals with chronic hyponatremia. It is recommended to increase plasma sodium concentration by no more than 8 to 10 mmol/L per 24 h in chronic hyponatremia.

Lack of astrocytes hinders parenchymal oligodendrocyte precursor cells from reaching a myelinating state in osmolyte-induced demyelination

Demyelinated lesions in human pons observed after osmotic shifts in serum have been referred to as central pontine myelinolysis (CPM). Astrocytic damage, which is prominent in neuroinflammatory diseases like neuromyelitis optica (NMO) and multiple sclerosis (MS), is considered the primary event during formation of CPM lesions. Although more data on the effects of astrocyte-derived factors on oligodendrocyte precursor cells (OPCs) and remyelination are emerging, still little is known about remyelination of lesions with primary astrocytic loss. In autopsy tissue from patients with CPM as well as in an experimental model, we were able to characterize OPC activation and differentiation. Injections of the thymidine-analogue BrdU traced the maturation of OPCs activated in early astrocyte-depleted lesions. We observed rapid activation of the parenchymal NG2⁺ OPC reservoir in experimental astrocyte-depleted demyelinated lesions, leading to extensive OPC proliferation. One week after lesion initiation, most parenchyma-derived OPCs expressed breast carcinoma amplified sequence-1 (BCAS1), indicating the transition into a pre-myelinating state. Cells derived from this early parenchymal response often presented a dysfunctional morphology with condensed cytoplasm and few extending processes, and were only sparsely detected among myelin-producing or mature oligodendrocytes. Correspondingly, early stages of human CPM lesions also showed reduced astrocyte numbers and non-myelinating BCAS1⁺ oligodendrocytes with dysfunctional morphology. In the rat model, neural stem cells (NSCs) located in the subventricular zone (SVZ) were activated while the lesion was already partially repopulated with OPCs, giving rise to nestin⁺ progenitors that generated oligodendroglial lineage cells in the lesion, which was successively repopulated with astrocytes and remyelinated. These nestin⁺ stem cell-derived progenitors were absent in human CPM cases, which may have contributed to the inefficient lesion repair. The present study points to the importance of astrocyte-oligodendrocyte interactions for remyelination, highlighting the necessity to further determine the impact of astrocyte dysfunction on remyelination inefficiency in demyelinating disorders including MS.

Severe hypernatremia and transient azotemia in a cat following inadvertent intravenous administration of a commercial polyethylene glycol solution

OBJECTIVE

To describe the clinical signs, clinicopathologic abnormalities, treatment, and outcome after IV administration of polyethylene glycol 3350 (PEG3350) in a cat.

CASE SUMMARY

A cat was inadvertently administered 6 g/kg of PEG3350 in electrolyte solution, IV, resulting in severe hypernatremia (203 mmol/L), diffuse encephalopathy, hemolysis, and moderate azotemia. The hemolysis and acute kidney injury observed immediately following PEG3350 administration resolved with supportive care. Administration of IV and oral electrolyte-free water slowly corrected the hypernatremia and the neurologic signs subsequently improved. Complete resolution of clinical signs was documented one month following hospital discharge. The PEG3350 concentrations in serum, plasma, and urine samples confirmed toxic exposure to PEG3350. Efficacy of treatment was evident by decreasing concentrations of PEG3350 in serum after the first 24 hours of treatment. Renal elimination of PEG3350 was significant and PEG3350 was still detected in the urine 17 days after exposure.

NEW INFORMATION PROVIDED

This is the first report to describe the clinical signs and clinicopathologic abnormalities in a cat intoxicated with IV PEG3350. Potential pathophysiologic mechanisms are discussed, and the successful supportive medical treatment is outlined.

Osmotic Demyelination: From an Oligodendrocyte to an Astrocyte Perspective

Osmotic demyelination syndrome (ODS) is a disorder of the central myelin that is often associated with a precipitous rise of serum sodium. Remarkably, while the myelin and oligodendrocytes of specific brain areas degenerate during the disease, neighboring neurons and axons appear unspoiled, and neuroinflammation appears only once demyelination is well established. In addition to blood‒brain barrier breakdown and microglia activation, astrocyte death is among one of the earliest events during ODS pathology. This review will focus on various aspects of biochemical, molecular and cellular aspects of oligodendrocyte and astrocyte changes in ODS-susceptible brain regions, with an emphasis on the crosstalk between those two glial cells. Emerging evidence pointing to the initiating role of astrocytes in region-specific degeneration are discussed.

Desmopressin acetate-induced water intoxication in a dog with psychogenic polydipsia

A 21-month-old male Border Collie presented to emergency service after a generalised tonic–clonic seizure. He received desmopressin acetate (1-Desamino-8-D-Arginin-Vasopressin, DDAVP) intraconjunctivally and intranasally for treatment of suspected central diabetes insipidus (DI) for a year, but water intake had recently increased again to 120–150 ml/kg/day. History, physical examination and clinicopathological findings, especially marked hyponatraemia, were consistent with water intoxication. The condition was stabilised by discontinuation of DDAVP and fluid restriction. Hyponatraemia resolved with frequent adjustments of fluid management according to physical parameters and electrolyte status. After exclusion of other causes for polyuria and polydipsia (PD), a modified water deprivation test led to diagnosis of psychogenic PD. Long-term outcome was excellent with water restriction and intensified dog training.

Magnetic resonance imaging appearance of the brain and cervical spinal cord in an edema disease affected pig

A 7-week-old male pig was presented with signs of a central nervous system disorder. An MRI of the head and cervical spine was performed immediately after euthanasia. The MRI revealed multifocal bilaterally symmetric T2-weighted hyperintense lesions in the brain and spinal cord, likely due to a toxic metabolic process. Histopathological examination supported the MRI findings and confirmed the diagnosis of edema disease due to Shiga-like toxin produced by Escherichia coli. This is the first case published of the MRI findings in an edema disease affected pig.

Hydrocortisone in the management of acute hypoadrenocorticism in dogs: a retrospective series of 30 cases

OBJECTIVES

The objectives of this study were to describe the efficacy, outcome and adverse effects of intravenous hydrocortisone and fluid therapy for the management of acute hypoadrenocorticism in dogs.

METHODS

A retrospective review of dogs with primary hypoadrenocorticism receiving intravenous hydrocortisone and fluid therapy was performed.

RESULTS

Thirty newly-diagnosed dogs were included. There was an excellent clinical response, with all dogs surviving to discharge within a median of 2 days. In 23 cases with complete data, the mean rate of change of sodium over 24 hours was 0·48 (±0·28) mmol/L/hour, while the mean rate of change of potassium was -0·12 (±0·06) mmol/L/hour. Circulating potassium concentration normalised in 68·4% and 100% of cases of by 12 and 24 hours, respectively. Additional treatment for hyperkalaemia was not found necessary. Plasma sodium concentration increased by >12 mmol/L/24 hours on 7 of 23 (30·4%) occasions. One dog exhibited associated temporary neurological signs.

CLINICAL SIGNIFICANCE

Intravenous hydrocortisone infusion and fluid therapy for the management of acute hypoadrenocorticism is associated with a rapid resolution of hyperkalaemia and is well tolerated with few adverse effects. Regular electrolyte monitoring is required to ensure that rapid increases in sodium concentration are avoided.

Endocrine emergencies in dogs and cats

Success in treatment of endocrine emergencies is contingent on early recognition and treatment. Many endocrine diseases presenting emergently have nonspecific signs and symptoms. In addition, these endocrine crises are often precipitated by concurrent disease, further making early identification difficult. This article concentrates on recognition and emergency management of the most common endocrine crises in dogs and cats.

Primary bilateral pontine demyelination in a cat with similarity to central pontine myelinolysis

An adult cat was presented with the history of 3 months' weight loss and more recent loss of balance and ataxia. An abdominal mass was palpable; results of neurologic examination suggested a brainstem disorder. The owners elected euthanasia. Postmortem findings included suppurative jejunal lymphadenitis and bilateral demyelination in the ventral pons with sparing of axons and neuronal soma. The location and character of the lesion mimicked those of human central pontine myelinolysis, an iatrogenic condition that may follow rapid correction of hyponatremia or develop spontaneously in patients with malnutrition or energy deprivation. In this cat, the poor nutritional state may have contributed to the development of this novel pontine lesion.

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.

Electrolyte disorders

Abnormal electrolyte concentrations occur commonly in hospitalized patients and may produce a variety of clinical symptoms, cause lack of response to therapeutics for primary clinical conditions, and affect clinical outcome. Recognition of electrolyte disturbances requires a high index of suspicion by the clinician for such a disturbance and prompt therapy to ensure a positive and timely outcome for the patient. This article discusses electrolyte abnormalities that occur in critically ill patients, with a review of diseases commonly associated with each electrolyte disturbance, and their recommended management.

Effects of an oral vasopressin receptor antagonist (OPC-31260) in a dog with syndrome of inappropriate secretion of antidiuretic hormone

OBJECTIVE

The syndrome of inappropriate secretion of antidiuretic hormone is a rare disorder in dogs characterised by hypo-osmolality and persistent arginine vasopressin production in the absence of hypovolaemia and/or hypotension. The study describes the efficacy and safety of the nonpeptide selective arginine vasopressin V2 receptor antagonist OPC-31260 in a dog with the naturally occurring syndrome.

DESIGN

The detailed case history of a dog with spontaneous syndrome of inappropriate secretion of antidiuretic hormone that received long-term therapy with oral OPC-31260 is presented. Effects of the first dose of OPC-31260 and of a dose administered after a continuous dosing period of 12 days are reported.

PROCEDURE

Packed cell volume, plasma sodium, total protein, arginine vasopressin, renin activity, atrial natriuretic peptide, urine specific gravity, urine output, heart rate and body weight were monitored for 2 h before, and for 4 h after, the first dose of OPC-31260. The same parameters plus plasma osmolality and urine osmolality were monitored when an identical dose was administered after 12 days of therapy.

RESULTS

Oral administration of OPC-31260 at 3 mg/kg body weight resulted in marked aquaresis with increased urine output and decline in urine specific gravity within 1 h. Corresponding increases in concentrations of plasma sodium, plasma osmolality and plasma renin activity were recorded over a 4 h period. Arginine vasopressin concentration remained inappropriately elevated throughout the study. Results were similar when the trial procedure was repeated after a stabilisation period of 12 days. Long-term therapy with OPC-31260 at a dose of 3 mg/kg body weight orally every 12 h resulted in good control of clinical signs with no deleterious effects detected during a 3-year follow-up period. Despite sustained clinical benefits observed in this case, plasma sodium did not normalise with continued administration of the drug.

CONCLUSIONS

Treatment of a dog with naturally occurring syndrome of inappropriate secretion of antidiuretic hormone with OPC-31260 at 3 mg/kg body weight orally every 12 h resulted in marked aquaresis and significant palliation of clinical signs with no discernible side-effects detected over a 3-year period. Thus, OPC-31260 appears to offer a feasible medical alternative to water restriction for treatment of dogs with syndrome of inappropriate secretion of antidiuretic hormone. Higher doses of OPC-31260 may be required to achieve and maintain normal plasma sodium in dogs with this syndrome.

Toxic and metabolic causes of seizures

Seizures are a relatively nonspecific response of the cerebral cortex to insult and can be caused by a variety of toxic or metabolic diseases. Seizure in response to extracranial disease are called reactive seizures. Toxins cause seizures by altering the balance of excitation and inhibition in the nervous system or interfering with energy metabolism. Many therapeutic or illicit drugs will cause seizures through similar mechanisms. Metabolic diseases can cause seizures by interfering with energy metabolism, changing osmolality, or producing endogenous toxins. In addition, metabolic disease may alter the pharmacokinetics of antiepileptic drugs or drugs that have the potential to cause seizures. While seizures represent a serious sign for many of these conditions, reactive epilepsy always carries the possibility that the seizures may be eliminated if the underlying cause is detected and corrected.

Hyponatremia

The serum sodium concentration reflects the osmolality of the extracellular fluid and provides no direct information about total body sodium content. Patients with hyponatremia may have decreased, normal, or increased total body sodium content. The first step in the approach to the patient with hyponatremia is measurement of plasma osmolality. Hyponatremia with normal plasma osmolality results from hyperlipemia or hyperproteinemia, whereas hyponatremia with increased plasma osmolality results from hyperglycemia or mannitol infusion. Patients with hyponatremia and decreased plasma osmolality may be hypovolemic, hypervolemic, or normovolemic. The volume status of the patient is best determined by history, physical examination, and a few ancillary tests (e.g., total plasma protein concentration, hematocrit, blood pressure, central venous pressure). The clinical signs of hyponatremia are related more to the rapidity of onset than to the severity of the associated plasma hypoosmolality and reflect influx of water into the central nervous system. The main goals of treatment in hyponatremia are to diagnose and manage the underlying disease and, if necessary, to increase serum sodium concentration and plasma osmolality.

Physiology of body fluids in the horse

This article presents a brief overview of the physiology of homeostasis in the horse and discusses the units of measurement by which dissolved electrolytes are assessed. Differences in electrolyte composition between compartments of the body and the manner in which water is exchanged between them are reviewed. The mechanisms by which alterations in osmolality and effective circulating volume are detected and the physiological responses to those alterations are presented.

Electrolyte and acid-base disturbances in the horse

Laboratory electrolyte and acid-base analyses are important for the characterization and assessment of the severity of disorders of fluid balance, and they enable the veterinarian to institute appropriate corrective therapeutic interventions. Abnormalities of electrolytes or acid-base rarely define the diagnosis, but certain diseases are characterized by predictable trends in these parameters. Important clinical situations in which assessment of electrolyte and acid-base status should be regarded as important to the equine practitioner include diarrhea, severe colic, peritonitis, pleuritis, dysphagia (inability to drink water or ingest food), neurologic dysfunction, exhaustion, renal failure, and rhabdomyolysis.