Effects of Oral Administration of a Commercial Activated Charcoal Suspension on Serum Osmolality and Lactate Concentration in the Dog

Considerations for deriving a safe intake of propylene glycol

The use of propylene glycol (PG) in food and other applications is widespread, and some estimates of dietary exposure to PG approach or exceed the Acceptable Daily Intake (ADI) of 25 mg/kg bw-day. The current ADI for PG applies a cumulative uncertainty factor of 100, which includes factors of 10 for both interspecies and intraspecies differences. Available toxicology studies and human data, however, indicate a plausible mode of action (MoA) that would support a chemical-specific adjustment factor (CSAF) of 1 for interspecies toxicodynamic differences, reducing the total uncertainty factor from 100 to 40. The MoA involves an increase in serum PG concentrations after metabolic saturation, leading to serum hyperosmolarity, which can ultimately cause hemolytic changes and red blood cell damage. Therefore, the species similarities in toxicodynamic response for this critical effect could support increasing the ADI from 25 to 62.5 mg/kg bw-day, applicable to both children and adults.

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.

Non-invasive Lactate Monitoring System Using Wearable Chipless Microwave Sensors with Enhanced Sensitivity and Zero Power Consumption

AbstractMonitoring lactate levels is an established method for determining hyperlactatemia in critically ill patients and assessing aerobic fitness. It is a widely used gold-standard technique in both professional and serious amateur sports. Non-invasive real-time lactate monitoring offers significant advantages over the current technology of finger-prick blood sampling. Possible candidate technology for developing non-invasive real-time lactate monitoring should be highly sensitive, flexible, and capable of real-time monitoring of lactate levels in interstitial fluid or within specific working muscle groups depending on the type of sport. Herein we describe a planar, flexible, passive, chipless tag resonator that is electromagnetically coupled to a reader placed in proximity to the lactate sensor tag. The tag resonator is a thin metallic tracing that can be taped on the skin. The resonance frequency of the tag fluctuates proportionately with changing lactate concentrations in a solution mimicking human interstitial fluid with very high sensitivity. The spectrum of the tag is reflected in the spectrum of the reader, which is a planar microwave resonator designed at a different frequency. The reader could be embedded in a cellphone or an application-specific wearable device for data communication and processing. The tag can accurately and reproducibly measure lactate concentrations in the range of 1 to 10 mM, which is in the physiological range of lactate observed at rest and during intense physical activity. Furthermore, the chrematistics of this technology will allow monitoring of lactate in specific working muscle groups.

Amitraz toxicosis in 3 dogs after being in a rice field

OBJECTIVE

To describe the clinical course and novel biochemical findings in 3 dogs with amitraz toxicosis.

CASE SERIES SUMMARY

Three Labrador Retrievers developed acute onset obtundation to stupor after being in a rice field. On admittance to the hospital, they all displayed bradycardia, hyperglycemia, hyperlactatemia, respiratory acidosis, and metabolic alkalosis. All clinical signs resolved in 18-48 hours with supportive care. One dog represented with similar clinical signs and biochemical abnormalities 3 days after discharge following spending time in a different rice field owned by the same owner. Toxicological analysis of serum from all 3 dogs and vomitus from 1 dog returned positive for amitraz and one of its metabolites.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first case series of dogs with confirmed amitraz toxicosis following an environmental exposure. Novel biochemical findings of hyperlactatemia, respiratory acidosis, and metabolic alkalosis were documented in all 3 dogs. Clinicians should be concerned for amitraz toxicosis when presented with an animal with the constellation of signs including decreased mental status, bradycardia, and hyperglycemia, particularly if relevant acid-base abnormalities are also detected.

Gastrointestinal obstruction secondary to activated charcoal granule impaction in a dog

OBJECTIVE

To describe a serious adverse event of gastrointestinal obstruction requiring surgery following routine administration of multiple doses of activated charcoal (AC) granules, which were prescribed for carprofen toxicosis.

CASE SUMMARY

A 2-year-old female neutered Airedale Terrier presented for ingestion of 207 mg/kg of carprofen. Decontamination was initiated with apomorphine to induce emesis. Along with additional supportive care, the dog received an initial dose of 75 mL of AC suspension containing sorbitol by mouth (15.6 g of AC, or 0.6 g/kg), followed by 50 g of AC granules every 8 hours for 4 additional doses. While hospitalized, the dog experienced clinical signs, including vomiting and black diarrhea, as well as bloodwork changes including mild to moderate elevations in kidney and liver enzymes. Given clinical improvement after 72 hours of hospitalization, the patient was discharged for monitoring and ongoing care at home. Two days later, the patient presented again for nausea, dark diarrhea with frank blood, and panting. Abdominal ultrasound showed findings suspicious for partially obstructive foreign material or atypical impacted fecal material partially occluding the distal ileum. Despite medical management overnight, recheck ultrasound the following day demonstrated persistent obstruction with ileal foreign material. Exploratory laparotomy and enterotomy revealed moderate distension and obstruction of the distal ileum with black granular foreign material consistent with charcoal granules. The patient remained in hospital for supportive care for 4 days following the procedure, and all clinical signs were resolved at the time of discharge.

NEW OR UNIQUE INFORMATION PROVIDED

This report documents a serious adverse event of gastrointestinal obstruction associated with routine multidose AC administration, which has been occasionally reported in people but not in dogs. The potential for this complication should be taken into account when prescribing multiple doses of AC granules.

Effect of single dose administration activated charcoal containing sorbitol on serum sodium concentration and hydration status in dogs

OBJECTIVE

To assess the administration of a commercially available activated charcoal suspension with sorbitol (ACS) on serum sodium concentrations and hydration status in healthy dogs.

DESIGN

Prospective study.

SETTING

Private referral hospital.

ANIMALS

Nine healthy adult dogs.

INTERVENTIONS

Dogs were administered 1 mg/kg maropitant (Cerenia; Pfizer Animal Health, New York, NY) intravenously 1 hour prior to charcoal administration. Dogs were administered a single dose of 2 g/kg ACS.

MEASUREMENTS AND MAIN RESULTS

Blood samples and body weights were obtained prior to charcoal administration and 2, 4, 6, 8, 10, and 12 hours post ACS administration. Venous sodium, potassium, chloride, blood urea nitrogen, creatinine, lactate, packed cell volume, and total plasma protein were measured at each time interval. All dogs returned 2-4 weeks after ACS administration for a 12 hour period of water restriction and to serve as their own control group. The same measurements were repeated during water restriction period as following ACS administration. The increase in serum sodium concentration was significantly higher following ACS administration when compared to control period (P = 0.0002). All dogs administered ACS experienced a significant degree of weight loss (P = 0.0371) when compared to the control period. Following administration of ACS, the hematocrit of the dogs administered ACS was found to be significantly increased (P = 0.0001), when compared to the control period.

CONCLUSION

Patients that are administered a single dose of ACS are at risk of developing dehydration and secondary hypernatremia as observed in the dogs during the study period. Patients receiving ACS should have electrolytes monitored and would benefit from fluid therapy as previously recommended.

Clinical use of plasma lactate concentration. Part 1: Physiology, pathophysiology, and measurement

OBJECTIVE

To review the current literature with respect to the physiology, pathophysiology, and measurement of lactate.

DATA SOURCES

Data were sourced from veterinary and human clinical trials, retrospective studies, experimental studies, and review articles. Articles were retrieved without date restrictions and were sourced primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Lactate is an important energy storage molecule, the production of which preserves cellular energy production and mitigates the acidosis from ATP hydrolysis. Although the most common cause of hyperlactatemia is inadequate tissue oxygen delivery, hyperlactatemia can, and does occur in the face of apparently adequate oxygen supply. At a cellular level, the pathogenesis of hyperlactatemia varies widely depending on the underlying cause. Microcirculatory dysfunction, mitochondrial dysfunction, and epinephrine-mediated stimulation of Na⁺ -K⁺ -ATPase pumps are likely important contributors to hyperlactatemia in critically ill patients. Ultimately, hyperlactatemia is a marker of altered cellular bioenergetics.

CONCLUSION

The etiology of hyperlactatemia is complex and multifactorial. Understanding the relevant pathophysiology is helpful when characterizing hyperlactatemia in clinical patients.

Retrospective evaluation of feline rodenticide exposure and gastrointestinal decontamination: 146 cases (2000-2010)

OBJECTIVE

To determine the prevalence of rodenticide exposure in cats, describe the use of gastrointestinal decontamination (GID) after rodenticide exposure, and examine the efficacy of GID following exposure to anticoagulant rodenticides (ACR).

DESIGN

Retrospective study from 2000-2010.

SETTING

Emergency service of an urban university teaching hospital.

ANIMALS

One hundred forty-six cats presented for rodenticide exposure.

MAIN RESULTS

Annually, the number of cats that were presented for rodenticide exposure averaged 13 of 3,336 (0.39%) and totaled 146 cases over 11 years. Cats that had been exposed to rodenticide were significantly more likely to be young (P < 0.001), sexually intact (P < 0.001), and presented in the fall season (P = 0.002). The majority of cats lived indoors (67.6%). The type of rodenticide involved in the exposure was unknown in 50% (71/142) of cases. Of the known types, ACRs were most common (59/142, 41.5%) followed by cholecalciferol (7/142, 4.9%) and bromethalin (5/142, 3.5%). Gastrointestinal decontamination was attempted in 21/36 (58%) cats with exposure to a known ACR. Emesis was attempted in 17/21 (81%) and charcoal administered in 14/21 (67%) cats that underwent GID. This study did not detect an effect of GID efforts on prothrombin time (PT) prolongation 48 hours after exposure to a known ACR.

CONCLUSIONS

Cats consume rodenticides. Due to the lack of evidence of altered outcome associated with GID in cats exposed to ACRs, a PT should be evaluated 48 hours after first exposure regardless of whether GID is performed. Treatment should be based on the results of the PT. Gastrointestinal decontamination should be performed at the clinician's discretion based on history, risks, calculated toxic dose, low prevalence of ACR toxicosis in cats, general resistance of cats to ACR toxicosis, and treatment options.

Update: Clinical Use of Plasma Lactate

Lactate is an essential, versatile metabolic fuel in cellular bioenergetics. In human emergency and critical care, lactate is used as a biomarker and therapeutic endpoint and evidence is growing in veterinary medicine supporting its clinical utility. Lactate production is a protective response providing ongoing cellular energy during tissue hypoperfusion or hypoxia and mitigating acidosis. Hence, hyperlactatemia is closely associated with disease severity but it is an epiphenomenon as the body attempts to protect itself. This article reviews lactate biochemistry, kinetics, pathophysiology, some practical aspects of measuring lactate, as well as its use in diagnosis, prognosis, and monitoring.

Point of Care Measurement of Lactate

Lactate is generated as a consequence of anaerobic glycolysis by all tissues of the body. Increased l-lactate, the isoform produced by most mammals, reflects increased anaerobic metabolism secondary to tissue hypoperfusion or tissue hypoxia in most clinical situations, and is called type A lactic acidosis. The utility of lactate measurement and serial lactate monitoring in veterinary patients has been demonstrated in multiple studies. Blood lactate concentration is significantly elevated in many disease processes including septic peritonitis, immune-mediated hemolytic anemia, Babesiosis, trauma, gastric dilation and volvulus, and intracranial disease. Lactate clearance can be used to assess response to fluid therapy, cardiovascular therapeutics, and blood product transfusion in patients affected by type A lactic acidosis. Lactate concentration in peritoneal, pericardial, and synovial fluid can also be used as a diagnostic tool. Point of care analyzers such as the Lactate Pro, Lactate Scout, Accutrend, iSTAT, and Lactate Plus have been shown to be accurate lactate measurement instruments in small animal patients.

Retrospective evaluation of hyperosmolar hyperglycemia in 66 dogs (1993-2008)

OBJECTIVES

To clinically characterize a large group of dogs with the hyperosmolar hyperglycemic state (HHS) and to determine whether 2 HHS subgroups, dogs with hyperosmolar ketonuric (HK) diabetes mellitus (DM) and dogs with hyperosmolar nonketonuric (HNK) DM were clinically different from one another.

DESIGN

Retrospective study. Records of 1,250 diabetic dogs that were examined between January 1993 and July 2008 were reviewed in order to identify dogs with HHS. Inclusion required a calculated serum osmolality ≥325 mOsm/kg, with or without ketonuria.

SETTING

University teaching hospital.

ANIMALS

Sixty-six dogs with HHS including 34 dogs with HK, 25 dogs with HNK, and 7 dogs with unclassified HHS.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

HHS was diagnosed in 5% of dogs with DM. HK and HNK dogs were similar to one another in regard to most historical, physical examination, and clinicopathologic variables as well as outcome. Sixty-two percent of dogs with HHS survived to discharge from the hospital. Poor outcome of HHS dogs was associated with abnormal mental status (P = 0.03) and a low venous pH (P = 0.045). Dogs with HK were significantly more likely to have acute pancreatitis (P = 0.046), higher body temperature (P = 0.006), higher WBC count (P = 0.01), and a shorter duration of clinical signs (P = 0.02) compared to dogs with HNK. Dogs with HNK had significantly higher BUN and creatinine concentrations (P = 0.0002 and P = 0.008, respectively) and higher calculated osmolality (P = 0.001) compared to dogs with HK.

CONCLUSIONS

HHS is a rare condition in which poor outcome is associated with abnormal mental status and low venous pH. Among dogs with HHS, the subgroup of dogs with HK has significantly more acute pancreatitis, shorter duration of clinical signs, and higher body temperature and WBC count compared to dogs with HNK, whereas dogs with HNK have more azotemia and higher calculated osmolality compared to dogs with HK.

A retrospective analysis of glycol and toxic alcohol ingestion: utility of anion and osmolal gaps

Background

Patients ingesting ethylene glycol, isopropanol, methanol, and propylene glycol ('toxic alcohols') often present with non-specific signs and symptoms. Definitive diagnosis of toxic alcohols has traditionally been by gas chromatography (GC), a technique not commonly performed on-site in hospital clinical laboratories. The objectives of this retrospective study were: 1) to assess the diagnostic accuracy of the osmolal gap in screening for toxic alcohol ingestion and 2) to determine the common reasons other than toxic alcohol ingestion for elevated osmolal gaps.

Methods

Electronic medical records from an academic tertiary care medical center were searched to identify all patients in the time period from January 1, 1996 to September 1, 2010 who had serum/plasma ethanol, glucose, sodium, blood urea nitrogen, and osmolality measured simultaneously, and also all patients who had GC analysis for toxic alcohols. Detailed chart review was performed on all patients with osmolal gap of 9 or greater.

Results

In the study period, 20,669 patients had determination of serum/plasma ethanol and osmolal gap upon presentation to the hospitals. There were 341 patients with an osmolal gap greater than 14 (including correction for estimated contribution of ethanol) on initial presentation to the medical center. Seventy-seven patients tested positive by GC for one or more toxic alcohols; all had elevated anion gap or osmolal gap or both. Other than toxic alcohols, the most common causes for an elevated osmolal gap were recent heavy ethanol consumption with suspected alcoholic ketoacidosis, renal failure, shock, and recent administration of mannitol. Only 9 patients with osmolal gap greater than 50 and no patients with osmolal gap greater than 100 were found to be negative for toxic alcohols.

Conclusions

Our study concurs with other investigations that show that osmolal gap can be a useful diagnostic test in conjunction with clinical history and physical examination.

Lactate in veterinary critical care: pathophysiology and management

The measurement of blood lactate in people has proven to be a useful tool in the diagnosis, monitoring, and prognosis of a wide range of clinical syndromes. Its use in small animals is increasing, and several studies have been completed that demonstrate its potential role in critical care. This article summarizes the current state of knowledge regarding the physiology and pathophysiology of lactate production and lactic acidosis; current indications and the utility of measurement in a critical care setting are described; novel applications in the evaluation of cavitary effusions are highlighted; and a guide to the therapy of lactic acidosis is presented.

Serial blood lactate concentrations in systemically ill dogs

BACKGROUND

Lactate concentration often is quantified in systemically ill dogs and interpreted based on human data. To our knowledge, there are no published clinical studies evaluating serial lactate concentrations as a prognostic indicator in ill dogs.

OBJECTIVES

Our objective was to perform a prospective study, using multivariate analysis, to determine whether serial lactate concentrations were associated with outcome in ill dogs requiring intravenous fluids.

METHODS

Eighty sick dogs had lactate concentrations evaluated, using an analyzer that measures lactate in the plasma fraction of heparinized whole blood, at 0 hours and 6 hours after initiation of treatment. Severity of illness and outcome (survivor, nonsurvivor) were determined by reviewing the patient's record 2 weeks after admission. Lactate concentrations, age, body weight, gender, and severity of illness were evaluated using multivariate analysis to determine their effects on outcome.

RESULTS

Dogs with lactate concentrations greater than the reference interval at 6 hours were 16 times (95% confidence interval = 2.32-112.71 times, P <.01) more likely not to survive compared to dogs with lactate concentrations within the reference interval. Lactate concentrations above the reference interval at 0 hours were not significantly related to outcome. However, hyperlactatemia that did not improve by > or = 50% within 6 hours was significantly associated with mortality (P = .024).

CONCLUSION

Dogs with a lactate concentration higher than the reference interval at 6 hours were more likely not to survive. These results indicate an association between lactate concentration and outcome and emphasize the importance of serial lactate concentrations in evaluating prognosis.