Steven E. Epstein

Incidence, Nature, and Etiology of Metabolic Acidosis in Dogs and Cats

BACKGROUND Metabolic acidosis is an important abnormality in ill and injured dogs and cats. OBJECTIVES To describe the incidence, nature, and etiology of metabolic acidosis in dogs and cats that had arterial or venous blood gases measured for any reason at a university teaching hospital. ANIMALS Dogs and cats at the Veterinary Medical Teaching Hospital. METHODS Acid base parameters and electrolyte and lactate concentrations in dogs and cats measured during a 13-month period were retrospectively retrieved from a computer database. Metabolic acidosis was defined as a standardized base excess (SBE) in dogs of <-4 mmol/L and in cats <-5 mmol/L. RESULTS A total of 1,805 dogs and cats were included; of these, 887 (49%) were classified as having a metabolic acidosis (753 dogs and 134 cats). Primary metabolic acidosis was the most common disorder in dogs, whereas mixed acid base disorder of metabolic acidosis and respiratory acidosis was most common in cats. Hyperchloremic metabolic acidosis was more common than a high anion gap (AG) metabolic acidosis; 25% of dogs and 34% of cats could not be classified as having either a hyperchloremic metabolic acidosis or a high AG metabolic acidosis. CONCLUSIONS AND CLINICAL IMPORTANCE Metabolic acidosis was found commonly in this patient population and was associated with a wide variety of disease processes. Mixed acid base disorders occur frequently and routine categorization of metabolic acidosis based on the presence of high AG or hyperchloremia may be misleading in a large proportion of cases.

Ivermectin‐induced blindness treated with intravenous lipid therapy in a dog

Objective To report a case of blindness due to the ingestion of ivermectin and subsequent successful treatment with intravenous lipid (IVL) therapy. Case Summary A female neutered Jack Russell Terrier was examined for acute onset of apparent blindness after being exposed to ivermectin the previous day. The dog appeared to be blind during initial examination. Pupillary light reflex, menace response, and dazzle reflex were not present in either eye. Fundic examination revealed small areas of linear retinal edema. Electroretinography (ERG) showed diminished activity in both eyes. Ivermectin was present in the serum on toxicological assay. Approximately 20 hours after exposure, IVL was infused. Within 30 minutes of initiating the infusion, the pupillary light reflexes returned in both eyes, and by the end of the infusion the patient behaved as if sighted. Fundic examination and ERG were unchanged at this time. The dog was tested for the multidrug resistance gene mutation and was unaffected. New or Unique Information Provided Ivermectin toxicity occurs in dogs with apparent blindness being a common clinical sign. This is the first case report of ivermectin-induced blindness evaluated with ERG before and after treatment with IVL in a dog unaffected by the multidrug resistance gene mutation. Treatment with an infusion of IVL therapy appeared to shorten the clinical course of disease in this patient without affecting ERG results.OBJECTIVE To report a case of blindness due to the ingestion of ivermectin and subsequent successful treatment with intravenous lipid (IVL) therapy. CASE SUMMARY A female neutered Jack Russell Terrier was examined for acute onset of apparent blindness after being exposed to ivermectin the previous day. The dog appeared to be blind during initial examination. Pupillary light reflex, menace response, and dazzle reflex were not present in either eye. Fundic examination revealed small areas of linear retinal edema. Electroretinography (ERG) showed diminished activity in both eyes. Ivermectin was present in the serum on toxicological assay. Approximately 20 hours after exposure, IVL was infused. Within 30 minutes of initiating the infusion, the pupillary light reflexes returned in both eyes, and by the end of the infusion the patient behaved as if sighted. Fundic examination and ERG were unchanged at this time. The dog was tested for the multidrug resistance gene mutation and was unaffected. NEW OR UNIQUE INFORMATION PROVIDED Ivermectin toxicity occurs in dogs with apparent blindness being a common clinical sign. This is the first case report of ivermectin-induced blindness evaluated with ERG before and after treatment with IVL in a dog unaffected by the multidrug resistance gene mutation. Treatment with an infusion of IVL therapy appeared to shorten the clinical course of disease in this patient without affecting ERG results.

Airway microbial culture and susceptibility patterns in dogs and cats with respiratory disease of varying severity

OBJECTIVE To compare airway microbiological culture and susceptibility results in 2 groups of dogs and cats: 1 with respiratory failure requiring positive pressure ventilation (PPV) and 1 with respiratory disease. DESIGN Retrospective study. SETTING University teaching hospital. ANIMALS Fifty-two dogs and cats requiring PPV that had an airway microbiologic culture submitted from October 1, 2003 to October 31, 2008 were included. One hundred and four airway microbiologic cultures from dogs and cats with respiratory disease not requiring PPV were randomly sampled for comparison. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Patients with respiratory failure were more likely to have a gram-negative enteric isolate identified (P<0.001), while patients with respiratory disease were more likely to have a gram-negative nonenteric isolate (P<0.001) or anaerobic isolate (P<0.001) identified. Aerobic bacterial isolates from patients with respiratory failure were less likely to be susceptible to ampicillin (P=0.006), amoxicillin/clavulonate (P<0.001), chloramphenicol (P=0.004), enrofloxacin (P<0.001), ticarcillin/clavulonate (P=0.004), and the combination of ampicillin with enrofloxacin (P<0.001) than were aerobic bacterial isolates from patients with respiratory disease. CONCLUSIONS Canine and feline patients with respiratory failure severe enough to require PPV exhibit a different pattern of bacterial isolates cultured from their airways when compared with isolates from patients with respiratory disease that has not resulted in ventilator dependence. These isolates are more likely to be resistant to commonly used antimicrobials/antimicrobial combinations than patients in the respiratory disease group. These findings suggest that in canine and feline patients with infectious lower respiratory tract disease, consideration of the severity of the pulmonary insult may allow for better prediction of likely isolates and their antimicrobial susceptibilities. Further prospective studies with a standardized collection technique are warranted.

Antimicrobial Susceptibility Patterns in Urinary Tract Infections in Dogs (2010–2013)

Background Urinary tract infections (UTIs) are common in dogs. The responsible bacterial populations have evolved with increasing resistance to many antimicrobials. Objective To characterize the antimicrobial susceptibility patterns of canine urinary tract isolates over a 51‐month period. Animals One thousand six hundred and thirty‐six bacterial isolates from 1,028 dogs. Methods Aerobic bacterial isolate growth and susceptibility data from urine cultures of dogs were identified, retrospectively. Medical records were reviewed to obtain signalment, comorbidities, and antimicrobial use in the previous 30 days. The UTIs were further categorized as uncomplicated, complicated, or pyelonephritis. Results Common bacterial isolates identified were Escherichia coli (52.5%), Staphylococcus spp. (13.6%), and Enterococcus spp. (13.3%). In vitro susceptibility among all isolates varied for commonly prescribed antimicrobials (amoxicillin [59%], amoxicillin/clavulanic acid [76%], cephalexin [66%], enrofloxacin [74%] and trimethoprim‐sulfamethoxazole [86%]). For all antimicrobials tested (except aminoglycosides), in vitro susceptibility was higher in uncomplicated versus complicated infections (P < .05). Uncomplicated infection isolate susceptibility rates remained ≤90% for PO administered antimicrobials. Administration of amoxicillin, doxycycline, and enrofloxacin, but not amoxicillin/clavulanic acid in the previous 30 days was associated with resistance to that antimicrobial. Multidrug resistant isolates of E. coli and Staphylococcus spp. were more common in dogs with complicated than uncomplicated UTIs (36% versus 21%, P < .0001). Conclusions and Clinical Importance In vitro susceptibility was highly variable and no PO administered antimicrobial had >90% efficacy among isolates tested. Multidrug resistance was frequent among isolates tested suggesting that routine culture and susceptibility testing is indicated. Previously prescribed antimicrobials may affect empirical choices made pending susceptibility testing.

RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 3: Basic life support.

OBJECTIVE To systematically examine the evidence on basic life support (BLS) in veterinary CPR and to determine knowledge gaps. DESIGN Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality, and development of consensus on conclusions for application of the concepts to clinical practice. Relevant questions were answered on a worksheet template and reviewed by the Reassessment Campaign on Veterinary Resuscitation (RECOVER) BLS domain members, by the RECOVER committee and opened for comments by veterinary professionals for 30 days. SETTING Academia, referral practice, and general practice. RESULTS Sixteen worksheets were prepared to evaluate techniques for chest compression and ventilation strategies as well as identification of cardiopulmonary arrest (CPA). Major recommendations arising from this evidence review include performing chest compressions at a rate of at least 100/min at a compression depth of one-third to half the width of the chest with minimal pauses, and early instigation of ventilation at a rate of 8-10 breaths/min in intubated patients, or using a 30:2 compression/ventilation ratio in nonintubated patients. CONCLUSIONS Although veterinary clinical trials are lacking, much of the experimental literature on BLS utilized canine models. The major conclusions from this analysis of the literature are the importance of early identification of CPA, and immediate initiation of BLS in these patients. Many knowledge gaps exist, most importantly in our understanding of the optimal hand placement and technique for chest compressions, warranting coordinated future studies targeted at questions of relevance to differences between veterinary species and humans.

Diagnostic utility of D-dimer concentrations in dogs with pulmonary embolism.

BACKGROUND Pulmonary embolism (PE) is a complication of systemic disease in dogs. Antemortem diagnosis is challenging because of the lack of a confirmatory test. OBJECTIVES To retrospectively determine the diagnostic utility of D-dimer concentrations in dogs with necropsy-confirmed PE. ANIMALS Ten dogs with PE confirmed at necropsy that had D-dimer concentrations measured and 10 control dogs with D-dimer concentrations available that lacked PE on necropsy. METHODS The computerized medical record database was searched for dogs with necropsy-confirmed PE that had D-dimer concentrations measured at that visit. An age-, sex-, and breed-matched control group was identified. Signalment, location of PE, and coagulation profiles were collected. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated using a D-dimer concentration of 250 ng/mL. RESULTS Coagulation profiles were not different between dogs with and without PE. Using 250 ng/mL as a cut-off D-dimer concentration, the sensitivity and specificity were 80 and 30%, respectively, for the diagnosis of PE. The NPV and PPV were 60 and 53.0%, respectively. D-dimer concentration <103 ng/mL had 100% sensitivity for ruling out PE and no value was 100% specific. CONCLUSIONS AND CLINICAL IMPORTANCE D-dimer concentrations <250 ng/mL have a high sensitivity for the absence of PE, but PE still can occur in dogs with a normal D-dimer concentration. Increased D-dimer concentrations are not specific for PE.

Evaluation of acid–base disorders in dogs and cats presenting to an emergency room. Part 1: Comparison of three methods of acid–base analysis

OBJECTIVE To compare the diagnostic performance of the traditional approach to acid-base analysis with the Stewart approach and a semiquantitative approach. DESIGN Prospective cohort study. SETTING University teaching hospital. ANIMALS A total number of 84 dogs and 14 cats presenting to a university teaching hospital emergency room. PROCEDURES All dogs and cats in which venous blood samples for acid-base, lactate, and serum biochemical analysis were all collected within 60 minutes of each other, over a 5-month enrollment period. Acid-base analysis was performed using the traditional approach, Stewart approach, and a semiquantitative approach. RESULTS Traditional acid-base analysis identified respiratory acid-base abnormalities in 14/98 animals and metabolic acid-base abnormalities in 67/98. A mixed disorder of metabolic acidosis and respiratory alkalosis was most common occurring in 29/98 patients. The Stewart approach identified metabolic abnormalities in 82/98 patients; strong ion difference abnormalities were evident in 68/98 cases; an increased strong ion gap acidosis was identified in 49/98 cases; and changes in the quantity of weak acids in 25/98 cases. The semiquantitative approach identified abnormalities in all cases evaluated. Of the 14 patients with a primary respiratory acid-base abnormality, the Stewart approach identified metabolic abnormalities in 9 and the semiquantitative approach found abnormalities in all animals. CONCLUSIONS AND CLINICAL RELEVANCE The physicochemical approaches diagnosed more acid-base abnormalities in this population than the traditional approach although many of the abnormalities identified were small and of unknown clinical relevance. The physicochemical approaches may provide greater insight as to the underlying etiology of abnormalities, which maybe of particular relevance to cases with changes in albumin and/or phosphorus concentration.

Incidence, Severity and Prognosis Associated with Hypernatremia in Dogs and Cats

Background Hypernatremia has been associated with substantial morbidity and death in human patients. The incidence and importance of hypernatremia in dogs and cats has not been determined. Hypothesis/Objectives To describe the incidence of and prognosis associated with hypernatremia in dogs and cats at a university teaching hospital. Animals A total of 16,691 dogs and 4,211 cats with measured blood or serum sodium concentration. Methods Retrospective study. Medical records of animals with a blood or serum sodium concentration measured during a 60‐month period were reviewed to determine the severity of hypernatremia and its associated case fatality rate. Cases with moderate (11–15 mmol/L above the reference range) or severe hypernatremia (≥16 mmol/L above the reference range) were further reviewed. Results A total of 957 dogs (5.7%) and 338 cats (8.0%) were diagnosed with hypernatremia. Case fatality rates of dogs and cats with hypernatremia was 20.6 and 28.1%, respectively compared to 4.4 and 4.5% with a normal blood or serum sodium concentration (P < .0001). The magnitude of hypernatremia was linearly associated with a higher case fatality rate (P < .0001). Hypernatremia was associated with a higher case fatality rate than hyponatremia. Among the animals with moderate or severe hypernatremia, 50% of dogs and 38.5% of cats presented with community‐acquired hypernatremia, and 50% of dogs and 61.5% of cats developed hospital‐acquired hypernatremia. Conclusions and clinical importance Hypernatremia was found infrequently in this population but was associated with increased case fatality rates in dogs and cats. Presence and severity of hypernatremia might be useful as a prognostic indicator.

Exudative Pleural Diseases in Small Animals

Exudative pleural diseases are a common cause of respiratory distress and systemic illness in dogs and cats. This article addresses the pathophysiology, development, and classification of exudative pleural effusions. The most current diagnostic strategies, causes, imaging findings, and medical or surgical treatment options for select diseases are reviewed in detail.

Comparative accuracy of several published formulae for the estimation of serum osmolality in cats

OBJECTIVE To determine the osmole gap utilizing 18 previously published formulae for the estimation of serum osmolality in cats. PROCEDURES Serum samples were frozen at -80°C after routine biochemical analysis. An Advanced Micro Osmometer 3300 was used to measure serum osmolality. Eighteen previously reported formulae were used to calculate osmolality from biochemical analysis results. The calculated osmolality was subtracted from the measured osmolality to determine the osmole gap. Osmole gaps for azotaemic and hyperglycaemic cats were compared to those from cats without azotaemia or hyperglycaemia using each formula. RESULTS The osmole gaps varied dependent on the formula used and the presence or absence of hyperglycaemia or azotaemia. Eleven formulae led to calculated osmolality and osmole gaps that were not statistically different when hyperglycaemia, azotaemia or both were present. Four of these 11 formulae resulted in osmole gaps near zero. For each formula used, the osmole gap increased with increasing osmolality. CLINICAL SIGNIFICANCE Multiple formulae to calculate serum osmolality can be used, but they result in significantly different osmole gaps. Clinicians should be aware of the specific reference interval for the formula being used. The formula [2(Na(+) ) + glucose + BUN] is recommended as it is easy to use and reliable even in the presence of hyperglycaemia and/or azotaemia.