Electrocardiographic assessment of hyperkalemia in dogs and cats

Clinical presentation, management, and survival in dogs with persistent atrial standstill in the United Kingdom

OBJECTIVES

To investigate the clinical and echocardiographic presentation of dogs with persistent atrial standstill (PAS), identify variables measured at first presentation that could predict their survival, and document the progression of the disease after pacing.

MATERIALS AND METHODS

Retrospective study of medical records of dogs diagnosed with PAS at three referral hospitals of the United Kingdom over seven years.

RESULTS

Twenty-six dogs were diagnosed with PAS during the study period. Median age of the population was three years (range: 7 months-12.5 years). The most common clinical sign was syncope (14/26). Twenty-four dogs received artificial pacemakers (PM). Major complications after PM implantation were observed in four dogs (4/24). Serial echocardiographic examinations showed that cardiac dimensions of PAS dogs with left atrial or left ventricular dilation at first presentation did not return to reference range after pacing. Further dilation of the cardiac chambers, recurrence of congestive heart failure (CHF), or development of new episodes of CHF were documented in 7, 4, and 10 PAS dogs, respectively, despite pacing. Median survival time for cardiac-related deaths after PM implantation was 1512 days (18-3207). Neither CHF nor echocardiographic variables at presentation predicted survival after PM implantation in PAS dogs.

CONCLUSIONS

PAS is an uncommon bradyarrhythmia, occurring in young adult dogs. Affected dogs were often presented with syncope. Whilst syncope resolved, cardiac remodeling persisted after PM implantation. Long-term survival was favorable after PM implantation and was not predicted by congestive status or cardiac chamber size at first presentation.

Frequency of arrhythmias detected in 9440 feline electrocardiograms by breed, age, and sex

OBJECTIVES

The purpose of this study was to describe the frequency of arrhythmias detected in unsedated feline patients from general practice settings.

ANIMALS

A total 10,638 feline electrocardiograms (ECGs) were retrospectively collected of which 9440 met the inclusion criteria.

METHODS

Recordings were evaluated by a board-certified cardiologist. If an arrhythmia was present in the ECG tracing, the cardiologist categorized the arrhythmia using pre-established keywords.

RESULTS

At least one arrhythmia was observed in 249 cases (2.64%, 95% confidence interval (CI): 2.34-2.98, 249/9440), with the most common arrhythmia encountered being ventricular premature complexes (1.63%, 95% CI: 1.39%-1.91%, 154/9440). Ragdoll cats had the highest odds of arrhythmia (odds ratio (OR): 3.17, 95% CI: 1.43-6.17, P=0.036). Both geriatric (Age: 13+ years, OR: 1.70, 95% CI: 1.24-2.34, P=0.013) and senior (Age: 10-13 years, OR: 1.68, 95% CI: 1.19-2.37, P=0.003) cats had higher odds of having an arrhythmia than adult cats. The odds of male cats having an arrhythmia were slightly higher than female (OR: 1.36, 95% CI: 1.06-1.76, P=0.018).

CONCLUSIONS AND RELEVANCE

Of the 9440 ECGs included in this study, at least one arrhythmia was detected in 249 distinct cases. Arrhythmias were more common in older cats, male cats and the Ragdoll cat breed. While it is important to note that the presence of an arrhythmia alone does not always indicate the presence of heart disease, further research on the association between breed cardiac health is needed.

Rebound hyperkalemia in a dog with albuterol toxicosis after cessation of potassium supplementation

OBJECTIVE

To describe the presentation of rebound hyperkalemia as a delayed side effect of albuterol toxicity in a dog.

CASE SUMMARY

A 3-year-old female neutered mixed-breed dog was presented for albuterol toxicosis that led to a severe hypokalemia, hyperlactatemia, and hyperglycemia. The dog also experienced sinus tachycardia and generalized weakness. Treatment was instituted with intravenous fluid therapy and potassium supplementation, and the dog was monitored with a continuous electrocardiogram. Resolution of hypokalemia was documented 12 hours after initial presentation, at which time fluid therapy and potassium supplementation were discontinued. There were no further periods of sinus tachycardia, but instead the dog developed ventricular ectopy with rapid couplets (instantaneous rates of 300/min). An echocardiogram revealed normal cardiac size and function. Twenty-four hours after presentation, the patient developed severe hyperkalemia, despite discontinuation of fluids and potassium supplementation for 12 hours. Serial venous and urinary electrolytes were performed for determination of the fractional excretion of electrolytes. These data confirmed rebound hyperkalemia (7.0 mmol/L), consistent with a markedly increased fractional excretion of potassium, and secondary to the release of potassium from inside the cells. Fluid therapy with dextrose supplementation was provided until 36 hours postpresentation. The hyperkalemia resolved, and the dog was discharged after 44 hours of hospitalization.

NEW OR UNIQUE INFORMATION PROVIDED

This case documents rebound hyperkalemia following treatment of albuterol toxicosis in a dog. This case highlights the importance of understanding the distribution of total body potassium when treating serum hypokalemia. Transcellular shifts of potassium, as in the case of albuterol toxicosis, can lead to rebound hyperkalemia even after discontinuation of potassium supplementation. This case further explores the utility of fractional excretion of electrolytes in elucidating the etiology and management of electrolyte disturbances.

HYPERKALEMIA IN FOUR ANESTHETIZED RED WOLVES (CANIS RUFUS)

Four clinically healthy red wolves (Canis rufus) developed hyperkalemia during routine anesthetic procedures. All cases were anesthetized using a combination of dexmedetomidine (10-24 mcg/kg), ketamine (2-3 mg/kg), and either midazolam (0.25-0.5 mg/kg) or butorphanol (0.2-0.48 mg/kg). Additional anesthetics were given to effect. Total anesthetic time ranged from 60 to 420 min. Three out of four cases were treated using terbutaline (0.01 mg/kg SC), which successfully resolved the hyperkalemia. No bradyarrhythmias were seen in any cases where electrocardiography (ECG) was monitored (3/4). All cases recovered from anesthesia, with one prolonged recovery. All animals are clinically healthy at the time of writing. Factors including anesthetic duration, the use of α-2 agonists, hyperthermia, and genetics are discussed as possible triggers for hyperkalemia. Serial blood gases, with electrolyte measurements, are recommended during anesthesia of red wolves, particularly when anesthetic time may be prolonged or the patient suffers from hyperthermia. Terbutaline appears to be a successful treatment should hyperkalemia arise.

The use of agitated saline as contrast agent in a contrast-enhanced cystosonography for detection of urinary bladder rupture in animal cadavers

OBJECTIVE

To determine the value of microbubble contrast cystosonography in the diagnosis of bladder rupture in animals.

DESIGN

Prospective, method comparison study from November 2019 to October 2020.

SETTING

University teaching hospital.

ANIMALS

Thirty-four ethically sourced cadavers of dogs, rats, and rabbits.

INTERVENTIONS

In a prospective and blinded study, the cadavers were divided into 2 randomized groups: with bladder rupture (CR), and without bladder rupture (SR). Urinary catheterization was performed in all cadavers. Through the urethral catheter, bladders in CR group were ruptured using a rigid stainless steel guide wire. Microbubble contrast was infused into the bladder through the urethral catheter, while a single, blinded observer sonographically assessed the bladder. The time to diagnosis and the number of attempts needed for diagnosis were recorded.

MEASUREMENTS AND MAIN RESULTS

The study included cadavers of 16 female Wistar rats, 6 female dogs, 11 male dogs, and 1 male rabbit. Time to diagnosis in dogs (2.25 ± 0.91 min) was statistically higher when compared to rats (1.15 ± 0.75 min; P = 0.03). Of the 34 cases, incorrect diagnosis of bladder rupture was made in only 2 dogs (6%), indicating a diagnostic sensitivity of 88.88%, specificity of 100%, and an accuracy of 94%. The positive predictive value was 1 and the negative predictive value was 0.9.

CONCLUSIONS

Our study showed that the described method is accurate, sensitive, and specific for the detection of bladder rupture in animal cadavers of different species, size, and sex.

Retrospective evaluation of acute hyperkalemia of unknown origin during general anesthesia in dogs

OBJECTIVE

To report and characterize cases of acute hyperkalemia of unknown origin in dogs under anesthesia.

STUDY DESIGN

Multicentric retrospective clinical study.

ANIMALS

Medical records of 19 client-owned dogs that developed acute hyperkalemia during anesthesia.

METHODS

Anesthetic records of dogs developing acute hyperkalemia from January 2015 to December 2022 were evaluated. Data collected included demographics, duration of anesthesia until the episode, electrolytes and blood gas measurements, electrocardiogram (ECG) abnormalities, drugs used as part of the anesthetic protocol, hyperkalemia treatment and outcome.

RESULTS

A total of 13 cases met the inclusion criteria with documented acute hyperkalemia with no apparent underlying cause during anesthesia. Dogs were [mean ± standard deviation (range)] 6.5 ± 5.0 (3-10) years old and weighed 18.0 ± 14.3 (5.1-40.0) kg. All dogs were administered dexmedetomidine and an opioid as part of the premedication. All dogs had inhalation anesthesia of >60 minutes' duration. The first clinical sign was bradycardia that was minimally responsive to anticholinergic administration and was often accompanied by moderate/severe hypotension. These signs were rapidly followed by ECG changes compatible with hyperkalemia and/or cardiac arrest. Rapid identification and treatment for hyperkalemia, with or without dexmedetomidine reversal, resulted in survival of 12 dogs and one fatality.

CONCLUSIONS AND CLINICAL RELEVANCE

Unknown origin hyperkalemia is a life-threatening complication that can occur during general anesthesia. In healthy dogs, preanesthetic administration of dexmedetomidine in association with an opioid and followed by inhalation anesthesia of more than 1 hour duration may predispose to this complication. A sudden decrease in heart rate >90 minutes after dexmedetomidine administration, or ECG changes, may warrant measurement of blood potassium concentrations.

Third-degree atrioventricular block with narrow QRS complexes in a case of hypoadrenocorticism in a dog

A 4-year-old dog presented with lethargy and bradycardia (heart rate 40 bpm). Electrocardiogram diagnosed third-degree atrioventricular block with narrow QRS complexes. An atropine response test did not result in a change of the heart rate. Venous blood gas documented moderate hyperkalaemia and an adrenocorticotrophic hormone stimulation test was consistent with hypoadrenocorticism. The patient repeatedly converted to sinus rhythm with normalisation of serum potassium levels following medical treatment. This is the first report of third-degree atrioventricular block in a patient with hypoadrenocorticism that was not vagally mediated and did not require pacemaker implantation, with conversion to sinus rhythm following treatment of the hyperkalaemia.

Effects of handling and storage on potassium concentration in plasma and serum samples obtained from cats

OBJECTIVE

To compare potassium concentrations in feline plasma and serum samples analyzed promptly after collection or after 20 to 28 hours of refrigerated storage.

ANIMALS

41 cats.

PROCEDURES

A venous blood sample was obtained from each cat. Aliquots were placed in 2 tubes without anticoagulant (blood was allowed to clot to derive serum) and 2 tubes with heparin (to derive plasma). One serum and 1 plasma sample were kept at room temperature and analyzed within 60 minutes after collection (baseline); the other serum and plasma samples were analyzed after 20 to 28 hours of refrigerated storage. At both time points, serum and plasma potassium concentrations were measured.

RESULTS

Median baseline serum potassium concentration (4.3 mmol/L) was significantly higher than median baseline plasma potassium concentration (4.1 mmol/L). The median difference between those values was 0.4 mmol/L (95% CI, 0.2 to 0.5 mmol/L). Compared with their respective baseline measurements, the median serum plasma concentration (4.8 mmol/L) and median plasma potassium concentration (4.6 mmol/L) were higher after 20 to 28 hours of refrigeration.

CLINICAL RELEVANCE

Results indicated that with regard to potassium concentration in feline blood samples, clotting or refrigerated storage for 20 to 28 hours results in a significant artifactual increase. Detection of an unexpectedly high potassium concentration in a cat may represent pseudohyperkalemia, especially if the blood sample was placed in a no-additive tube, was stored for 20 to 28 hours prior to analysis, or both.

Suspected vagal reflex and hyperkalaemia inducing asystole in an anaesthetised horse

A 10‐year‐old 466 kg mustang gelding presented to an equine referral hospital for surgical repair of nasal, frontal and lacrimal bone fractures from an unknown trauma. Surgical repair was performed under general anaesthesia, including a right‐sided maxillary regional anaesthetic block with mepivacaine hydrochloride. Progressive hyperkalaemia was documented perianaesthetically (T‐3 mins; 134 mins after induction; potassium 6.4 mmol/L (ref 3.5‐5.1 mmol/L). Perianaesthetic bradycardia was attributed to alpha −2 agonist infusion administration, and other characteristic ECG changes (flattened P waves, narrow T waves of increased amplitude, prolonged QRS complex) were not documented. Asystole occurred 137 min after induction of anaesthesia; however, a review of the available literature suggests the degree of hyperkalaemia documented was unlikely to be the primary cause of asystole but may have been a contributing factor. It is hypothesised that a trigeminocardiac reflex was the primary contributory factor to asystole in the described case, and may represent a maxillomandibulocardiac reflex that has not been previously described in the horse.

Biochemical, electrolytic, and cardiovascular evaluations in cats with urethral obstruction

Background and Aim:

Urethral obstruction (UO) is a common condition in feline medicine. Severe acid-base and electrolyte disorders promote relevant electrocardiographic changes in these animals. Cardiac biomarkers such as cardiac troponin I have been shown to be useful in identifying cats with myocardial disease, but it has not been investigated whether UO leads to myocardial damages. This study aimed to evaluate biochemical changes, electrocardiographic findings, troponin I measurements, and electrolyte disturbances for 7 days in cats with UO.

Materials and Methods:

This follow-up prospective study included 33 cats diagnosed with UO for 7 days. For all cats, clinical examination, serum biochemistry, electrolyte analyses, blood pressure, and electrocardiography were performed. Cardiac troponin I was measured in the serum in 16 cats at 3 different times.

Results:

The mean age of the feline population was 1.83±1.58 years (mean±standard deviation). Creatinine, urea, blood urea nitrogen, glucose, phosphorus, base excess, bicarbonate, and serum potassium decreased significantly (p≤0.05), while ionic calcium and blood pH increased significantly (p≤0.05) at different times. Electrocardiographic abnormalities were observed in 21/33 (63.63%) of the felines on admission day. The electrocardiographic abnormalities were no longer observed on the subsequent days. Only one feline showed changes in troponin I cardiac concentrations.

Conclusion:

This study suggests the sum and severity of electrolyte abnormalities aggravate the clinical and cardiovascular status of these patients. However, cTnI, blood pressure, and heart rate within the reference range do not exclude the presence of major cardiovascular and metabolic abnormalities. The hyperglycemia in felines with UO appears to be associated with decreased renal clearance, which may reflect the severity of hyperkalemia and azotemia. The metabolic and cardiovascular changes of these felines are minimized by the establishment of appropriate intensive care; however, cardiac and blood gas monitoring is essential to assess the severity of the disease.

Transient deep and giant negative T waves in dogs with myocardial injury

INTRODUCTION

Although transient deep and giant negative T waves (NTWs) may develop during myocardial injury (MI) in humans, no data exist on this repolarization abnormality in canine MI. Therefore, this study aimed to describe the occurrence of transient deep/giant NTWs in dogs with MI.

ANIMALS, MATERIALS AND METHODS

Medical records were retrospectively searched to identify dogs with MI and transient deep/giant NTWs. Signalment, history, and selected diagnostic test results were reviewed. Data analysis was descriptive.

RESULTS

Six cases were diagnosed with MI associated with deep (n = 1) and giant (n = 5) transient NTWs. Myocardial injury was classified as acute in all cases and was due to snake envenomation (n = 3), sepsis (n = 2), and systemic inflammatory response syndrome (n = 1). At the time of deep/giant NTWs identification, all dogs had elevated cardiac troponin I and ≥1 echocardiographic abnormality of the left ventricular structure and/or function. Moreover, all dogs with giant NTWs had prolonged QT intervals. After the MI resolution, T-wave polarity and QT-interval duration became normalized in all dogs. Moreover, left ventricular morphological and functional parameters were completely normalized in four dogs. In contrast, ventricular echogenicity remained heterogeneous in two dogs, despite otherwise normalized ventricular parameters. Five dogs were still alive at the conclusion of the study.

CONCLUSIONS

Transient deep/giant NTWs may develop in dogs with acute MI and T-wave polarity changes seem to occur synchronously with the evolution of myocardial damage. Moreover, transient deep/giant NTWs seem associated with a favorable prognosis in canine MI.

THE EFFECTS OF PROCEDURE DURATION AND ATIPAMEZOLE ADMINISTRATION ON HYPERKALEMIA IN TIGERS (PANTHERA TIGRIS) AND LIONS (PANTHERA LEO) ANESTHETIZED WITH α-2 AGONISTS

A retrospective analysis of 40 extended (>2 hr) anesthetic events in eight lions (Panthera leo) and 32 tigers (Panthera tigris) was performed using a hierarchical linear growth curve model to assess the effects of anesthetic time, α-2 adrenoreceptor agonist dosages, administration of atipamezole, and biochemical parameters on rising plasma K⁺ concentrations. Hyperkalemia was first noted at a mean time of 187 min (range: 131-226 min), with time under anesthesia as a statistically significant predictor of K⁺ concentration (P < 0.0001). A significant two-way interaction between time and atipamezole administration (P = 0.0082) for rising K⁺ concentrations was demonstrated, indicating that administration of atipamezole can mitigate the rise in K⁺ concentrations. Administration of atipamezole beyond 150 min of anesthetic time was less effective in reducing K⁺ concentrations than if administered earlier. Electrocardiographic abnormalities were noted in eight animals, including three hyperkalemic individuals. Lions developed significantly greater plasma K⁺ concentrations than tigers (P = 0.0009) during anesthesia. No biochemical parameter was identified as a significant indicator of which individuals will develop hyperkalemia. Clinicians anesthetizing any large nondomestic felid should monitor electrolytes regularly during anesthetic events; consider early, partial- to full-dose reversal of α-2 agonists; and be prepared to correct potentially life-threatening electrocardiographic abnormalities resulting from hyperkalemia.

Successful resolution of urothorax secondary to non-traumatic uroabdomen in a cat managed with peritoneal dialysis as a bridge to surgery

Case summary

A 9-year-old neutered male domestic shorthair cat was presented for evaluation of severe hemodynamic collapse and suspected lower urinary tract disease. On admission, severe metabolic acidosis, hyperkalemia and azotemia, and electrocardiographic findings consistent with cardiotoxicity were identified. The diagnosis of uroabdomen was made based on abdominal fluid to plasma concentration ratios of creatinine and potassium. A central line catheter was placed percutaneously into the abdomen for peritoneal drainage and used for peritoneal dialysis as a bridge to surgery. Retrograde contrast cystography confirmed rupture of the urinary bladder. Point-of-care ultrasound of the chest postoperatively revealed the presence of mild pleural effusion. Echocardiography was then performed showing no evidence of cardiac disease. Pleural fluid analysis revealed a transudate with a creatinine ratio of 2.38 ([Creatinine]_{pleural fluid}/[Creatinine]_plasma), consistent with the diagnosis of urothorax. The cat recovered uneventfully from surgery and was monitored for signs of respiratory distress during the rest of its stay in hospital. The cat was discharged 4 days later and the pleural effusion resolved without further medical intervention.

Relevance and novel information

There is limited information on the causes of urothorax and uroabdomen management of feline patients. Pleural effusion is a complication observed in critically ill cats secondary to fluid overload, underlying cardiomyopathy, primary thoracic pathology or a combination of these. To our knowledge, this is the first report of urothorax in a cat secondary to non-traumatic uroabdomen. Careful monitoring of respiratory signs consistent with pleural space disease is recommended in cases of uroabdomen.

Repeated hyperkalaemia during two separate episodes of general anaesthesia in a nine-year-old, female neutered greyhound

There is an increasing awareness of the development of hyperkalaemia during anaesthesia in otherwise healthy veterinary patients. In the human literature 63 per cent of in-hospital hyperkalaemic episodes are associated with drug administration. Anecdotal veterinary reports have suggested that a genetic component may also play a role, with greyhounds seemingly more susceptible to the development of hyperkalaemia under anaesthesia. This case report identifies the repeated development of hyperkalaemia, and its treatment, during two separate episodes of general anaesthesia in a nine-year-old, female neutered greyhound. The first episode of hyperkalaemia (7.89 mmol/l) was identified due to bradycardia and second-degree atrioventricular block on electrocardiogram. Treatment was with intravenous calcium gluconate, insulin, glucose and fluid therapy. The second episode (6.60 mmol/l) was associated with spiked T-waves, and treatment was with insulin and glucose infusions to allow completion of the anaesthetic and surgery. Possible causes and treatments are discussed, and the need for reporting of such cases is highlighted.

Electrocardiographic findings in 130 hospitalized neonatal calves with diarrhea and associated potassium balance disorders

Background

Hyperkalemia in neonatal diarrheic calves can potentially result in serious cardiac conduction abnormalities and arrhythmias.

Objectives

To document electrocardiographic (ECG) findings and the sequence of ECG changes that are associated with increasing plasma potassium concentrations (cK⁺) in a large population of neonatal diarrheic calves.

Animals

One hundred and thirty neonatal diarrheic calves (age ≤21 days).

Methods

Prospective observational study involving calves admitted to a veterinary teaching hospital.

Results

Hyperkalemic calves (cK⁺: 5.8‐10.2, blood pH: 6.55‐7.47) had significantly (P < .05) longer QRS durations as well as deeper S wave, higher T wave, and higher ST segment amplitudes in lead II than calves, which had both venous blood pH and cK⁺ within the reference range. The first ECG changes in response to an increase in cK⁺ were an increase in voltages of P, Ta, S, and T wave amplitudes. Segmented linear regression indicated that P wave amplitude decreased when cK⁺ >6.5 mmol/L, S wave amplitude voltage decreased when cK⁺ >7.4 mmol/L, QRS duration increased when cK⁺ >7.8 mmol/L, J point amplitude increased when cK⁺ >7.9 mmol/L, and ST segment angle increased when cK⁺ >9.1 mmol/L. P wave amplitude was characterized by a second common break point at cK⁺ = 8.2 mmol/L, above which value the amplitude was 0.

Conclusions and Clinical Importance

Hyperkalemia in neonatal diarrheic calves is associated with serious cardiac conduction abnormalities. In addition to increased S and T wave amplitude voltages, alterations of P and Ta wave amplitudes are early signs of hyperkalemia, which is consistent with the known sensitivity of atrial myocytes to increased cK⁺.

Multivariable analysis of the association between electrolyte disturbances and mortality in cats

OBJECTIVES

Electrolyte disorders have been individually associated with mortality in small populations of cats with specific conditions, but the associations and interactions between electrolyte disturbances and outcome have not been evaluated in a large, heterogeneous population. It was hypothesized that abnormalities of sodium, chloride, potassium and calcium concentrations would be independently and proportionately associated with death from natural causes and with all-cause mortality in cats.

METHODS

An electronic database containing 7064 electrolyte profiles was constructed to assess the association between disorders of sodium, potassium, corrected-chloride and ionized calcium concentrations with non-survival by multivariable modelling. A second database containing 2388 records was used to validate the models constructed from the first database.

RESULTS

All four electrolytes assessed had non-linear U-shaped associations with case fatality rates, wherein concentrations clustered around the reference interval had the lowest case fatality rates, while progressively abnormal concentrations were associated with proportionately increased risk of non-survival (area under the receiver operator characteristic curve [AUROC] 0.689) or death (AUROC 0.750).

CONCLUSIONS AND RELEVANCE

Multivariable modelling suggested that these electrolyte disturbances were associated with non-survival and with death from natural causes independent of each other. The present study suggests that measurement of electrolyte concentrations is an important component of the assessment of cats in emergency rooms or intensive care units. Future studies should focus on confirming these associations in a prospective manner accounting for disease severity.

Electrolyte Disturbances Are Associated with Non-Survival in Dogs-A Multivariable Analysis

Electrolyte disorders have been individually associated with mortality in small populations of dogs and cats with specific conditions, but the associations and interactions between electrolyte disturbances and outcome have not been evaluated in a large, heterogeneous population. It was hypothesized that abnormalities of sodium, chloride, potassium, and calcium concentrations would be independently and proportionately associated with death from natural causes and with all-cause mortality in dogs. An electronic database containing 33,117 electrolyte profiles was constructed to retrospectively assess the association between disorders of sodium, potassium, corrected chloride, and ionized calcium concentrations with non-survival and with death excluding euthanasia by multivariable modeling. A second database containing 11,249 records was used to validate the models constructed from the first database. All four electrolytes assessed had non-linear U-shaped associations with case fatality rates, wherein concentrations clustered around the reference interval had the lowest case fatality rates, while progressively abnormal concentrations were associated with proportionately increased risk of non-survival (AUROC 0.624) or death (AUROC 0.678). Multivariable modeling suggested that these electrolyte disturbances were associated with non-survival and with death from natural causes independent of each other. This study suggests that measurement of electrolyte concentrations is an important component of the assessment of dogs in emergency rooms or intensive care units. Future studies should focus on confirming these associations in a prospective manner accounting for disease severity.

Severe hyperkalemia presenting with wide-complex tachycardia in a puppy with acute kidney injury secondary to leptospirosis

OBJECTIVE

To describe a case of hyperkalemia coinciding with wide-complex tachycardia (WCT) in a dog with acute kidney injury secondary to leptospirosis infection.

CASE SUMMARY

An 11-week-old Golden Retriever-Standard Poodle cross puppy was referred for acute kidney injury and hepatopathy. WCT coinciding with marked hyperkalemia was identified on presentation. Tachycardia persisted until resolution of hyperkalemia.

NEW OR UNIQUE INFORMATION PROVIDED

To our knowledge, this is the first report of severe hyperkalemia presenting with WCT in a dog. Hyperkalemia should be considered a differential for WCT in dogs.

Routine Screening Examinations in Attendance of Cats With Obstructive Lower Urinary Tract Disease

This study evaluates the clinical findings obtained in routine screening examinations in cats with obstructive feline lower urinary tract disease at the time of service. Twenty-six cats with urethral obstruction were assessed by physical examination, blood pressure, electrocardiogram, and laboratory tests. Cats with signs of obstruction less than 36 hours before the service were in a state of alert, with body temperature and heart rate higher compared with cats in lethargy and stupor, obstructed up to 36 hours. The results revealed that 30.76% of the cats were hypertensive (>140mmHg). Arrhythmias were found in 15.38% of the cats with potassium >8.5mEqL. Creatinine, phosphorus, magnesium, potassium, and lactate concentrations were higher in cats obstructed more than 36 hours. All these data claim that a protocol of examinations should be established for obstructed cats, principally to stabilize the cat before the anesthesia for unobstruction.

Perioperative Acid-Base and Electrolyte Disturbances

Obtaining and interpreting blood gas and electrolyte levels is essential in the management of perioperative veterinary patients. Metabolic and electrolyte alterations are common in critically ill surgical patients, and can lead to alterations in cardiovascular function, neurologic status, respiratory function, and even response to various drug therapies. Several common perioperative conditions are discussed in this article, including metabolic disturbances, electrolyte abnormalities (hyponatremia and hypernatremia, hyperkalemia), and respiratory abnormalities.

Retrospective study of the perioperative management and complications of ureteral obstruction in 37 cats

OBJECTIVES

To describe perioperative management and complications, risk factors and mortality rates in cats anaesthetized for treatment of ureteral obstruction.

STUDY DESIGN

Retrospective, clinical, cohort study.

ANIMALS

Thirty-seven client-owned cats anaesthetized for ureteral surgery.

METHODS

Records with sufficient data for cats treated between March 2010 and March 2013 were examined for breed, age, gender, history, concurrent diseases, pre- and post-anaesthetic biochemical and haematological parameters, American Society of Anesthesiologists classification, anaesthetic protocol, surgical technique, surgeon, perioperative complications and mortality within 48 hours after extubation. Associations between risk factors and outcome variables were evaluated using univariable analysis. Odds ratios and 95% confidence intervals were calculated for significant parameters. Sensitivity and specificity using receiving operator characteristic curve analysis were calculated for creatinine, potassium level and standard base excess (SBE) to denote survival or non-survival.

RESULTS

Preoperatively, all cats were azotaemic: mean±SD urea was 31.6 ± 26.9 mmol L(-1) and median (range) creatinine was 562 μmol L(-1) (95 μmol L(-1) to off scale). Thirteen cats were hyperkalaemic (K+ 6.5 mmol L(-1)). Anaesthesia-related complications included bradycardia (n=8, 21.6%), hypotension (n=15, 40.5%) and hypothermia (n=32, 86.5%). Seven cats (18.9%) died postoperatively. Non-survivors were significantly (p=0.011) older (9.8±1.9 years) than survivors (6.4±3.1 years) and had higher potassium concentrations (p=0.040). Risk factors associated with mortality were ASA classes IV and V (p=0.022), emergency procedures (p=0.045) and bicarbonate administration (p=0.002). Non-survivors had higher creatinine concentrations (p=0.021) and lower SBE (p=0.030).

CONCLUSION AND CLINICAL RELEVANCE

Intraoperative anaesthetic complications were common; increased age, poor health status, preoperative bicarbonate administration, hyperkalaemia and increased creatinine were associated with increased risk for death and can be used to predict risk for complications.

Management of urinary tract emergencies in small animals

This article focuses on some of the most commonly seen urinary tract emergencies in dogs and cats, with emphasis on basic pathophysiology, diagnosis, and emergency management of these cases.

The flat cat: 2. the emergency database and management of common metabolic abnormalities

AIM

Detailed information regarding the causes and treatment of acute collapse in the cat can be difficult to locate in a single published source. This two-part review aims to provide a logical approach to the clinical assessment and stabilisation of the critically ill collapsed cat.

PRACTICAL RELEVANCE

Laboratory evaluation, in the form of an emergency database, is an important part of the initial assessment of a collapsed patient and should be considered in conjunction with physical abnormalities.

CLINICAL CHALLENGES

Rapid identification and correction of life-threatening metabolic abnormalities, including hypoglycaemia, hypocalcaemia and hyperkalaemia, is essential in stabilising this group of patients. Clinicians often lack confidence if they are not dealing with these problems regularly.

AUDIENCE

The information provided in this article will be of use to any veterinarian working with feline patients and particularly those dealing with emergencies on a regular basis.

EVIDENCE BASE

There is an extensive body of published literature, both original studies and textbook chapters, pertaining to the causes and treatment of the important metabolic abnormalities covered in this article. The authors draw on information from original articles, reviews and their clinical experience to provide simple but detailed practical information to guide interpretation of the emergency database and its application to therapy in the emergency setting.

Acid-base and electrolyte balance following administration of three crystalloid solutions in dogs undergoing elective orthopaedic surgery

OBJECTIVE

To compare acid-base balance and incidence of hyperchloraemic metabolic acidosis following administration of three crystalloid solutions to dogs undergoing anaesthesia for orthopaedic surgery.

STUDY DESIGN

Prospective, randomised, clinical study.

ANIMALS

Sixty dogs.

METHODS

During a non-standardised anaesthetic, 0.9% saline (S), Hartmann's solution (H) or a polyionic glucose-free maintenance solution (M) was administered IV at 10 mL kg(-1)  hour(-1) . Venous blood pH, PCO2 , PCV, total protein, urea, sodium, potassium and chloride concentrations were measured at induction of anaesthesia (T0) and after 2 hours of fluid therapy (T2). Base excess (BE), bicarbonate, corrected chloride concentration (corrCl), osmolality, change in plasma volume (PV) and strong ion gap (SIG) were calculated. Changes in variables within groups (1-sample Student's t-test/Wilcoxon signed rank test) and between groups (1-way anova/Kruskal-Wallis) were assessed. Data are presented as median (interquartile range). Significance was set at p < 0.05.

RESULTS

No significant differences existed between groups for pH, PCO2 , PCV, total protein, urea, potassium, corrCl, PV and SIG. Potassium significantly increased in all groups. Significant differences existed between groups S and M for BE, sodium, chloride, bicarbonate and osmolality, and between groups H and M for sodium and osmolality. Chloride concentration significantly changed from 116 (114-117) to 117 (116-119) mmol L(-1) in group S, 116 (115-118) to 115 (113-117) mmol L(-1) in group H and 116 (115-118) to 114 (113-118)  mmol L(-1) in group M. In groups H and M, sodium and osmolality decreased, and BE and bicarbonate concentration increased significantly. Plasma volume increased by 28 (14-44)%, 25 (5-40)% and 24 (13-33)% in groups S, H and M, respectively.

CONCLUSION AND CLINICAL RELEVANCE

Hyperchloraemic metabolic acidosis did not develop after intraoperative 0.9% saline, Hartmann's solution or maintenance solution at 10 mL kg(-1)  hour(-1) for 2 hours in dogs undergoing elective orthopaedic surgery. Bicarbonate and BE increased after Hartmann's and maintenance solutions. Increases in potassium concentration were unexplained.

Feline acute kidney injury: 2. Approach to diagnosis, treatment and prognosis

PRACTICAL RELEVANCE

Feline acute kidney injury (AKI) is a commonly recognized problem in small animal practice that requires prompt diagnosis and directed therapy. There are many treatment methods with which practitioners should be familiar, including medical options, surgical interventions and renal replacement therapy (dialysis). It is important to know which option is most appropriate for each cause and stage of AKI to deliver the most effective therapy.

CLINICAL CHALLENGES

AKI can cause vague clinical signs, but a vast array of life-threatening sequelae. Rapid recognition of potential complications and knowledge of treatment options is imperative for successful management. Feline patients also require an understanding of their unique physiology as it relates to the therapeutic plan.

AUDIENCE

This two-part review article is directed at small animal practitioners as well as specialists. Part 2 discusses the diagnosis of AKI in cats using physical examination findings, clinicopathologic results and imaging modalities. The treatment of AKI and its sequelae is also reviewed, with information on recent advances in this area.

EVIDENCE BASE

While there is very limited data comparing the outcomes of various treatment options, there is literature addressing the use of several medications, as well as renal replacement therapy, in cats.