Primary alimentary lymphoma with metastasis to the liver causing encephalopathy in a horse

A 23‐year‐old, 467‐kg Palomino mare was examined for evaluation of sudden onset severe ataxia and depression. The mare had been found down in a pasture and was unable to rise. She was observed, by her owner, to be normal 24 hours earlier. This mare had resided with this owner for approximately 1.5 years, had always lived out on pasture, and had experienced numerous episodes of colic since the time she was purchased. Recent reported feed changes included introduction of new hay. Upon arrival at the hospital, the mare was severely ataxic in all 4 limbs and extremely disoriented. She head‐pressed several times during the course of the evaluation and yawned repeatedly. The mare was tachycardic, with a heart rate of 98 beats per minute, and tachypneic, with a respiratory rate of 60 breaths per minute, and the mucous membranes were hyperemic and purple, with a capillary refill time of greater than 3 seconds. The mare was blind bilaterally, as indicated by absence of both menace and pupillary light responses. She had bilateral facial nerve paralysis and decreased hypoglossal nerve function. She was able to prehend, but was dysphagic with decreased tongue tone and movement. Analysis of the venous blood revealed metabolic acidosis and respiratory alkalosis with a normal pH of 7.38 (reference range 7.32–7.44), HCO₃ of 13 mEq/L (reference range 25–30 mEq/L), PCO₂ of 21.2 mmHg (reference range 36–46 mmHg), and BE of ‐12 mEq/L (reference range ‐1‐1 mEq/L).^a It also revealed a low blood urea nitrogen concentration of 8 mg/dL (reference range 11–27 mg/dL) and a high blood glucose concentration of 263 mg/dL (reference range 63–134 mg/dL).^a Both packed cell volume and total solids were high at 52% (reference range 32–53%), and 8 g/dL (reference range 5.8–7.7 g/dL), respectively. The blood ammonia concentration was 120 μmol/L (reference range 18–78 μmol/L)^b.     

What is your diagnosis? Marked hyperchloremia in a dog

Abstract: A 5‐year‐old neutered male Cavalier King Charles Spaniel was evaluated for a 3‐week history of progressive paresis. The dog had been receiving potassium citrate capsules to acidify urine for the past 2 years because of an earlier history of urolithiasis. Results of neurologic examination, spinal cord radiography, and magnetic resonance imaging of the skull and spinal cord revealed no lesions that could have accounted for the neurologic signs. The main abnormalities on a clinical chemistry profile were marked hyperchloremia (179 mmol/L, reference interval 108–122 mmol/L) and an anion gap of ?50.4 mmol/L (reference interval 16.3–28.6 mmol/L). Because of the severe hyperchloremia, serum bromide concentration was measured (400 mg/dL; toxic concentration >150 mg/dL; some dogs may tolerate up to 300 mg/dL). Analysis of the potassium citrate capsules, which had been compounded at a local pharmacy, yielded a mean bromide concentration of 239 mg/capsule. Administration of the capsules was discontinued and there was rapid resolution of the dog's neurologic signs. This case of extreme bromide toxicity, which apparently resulted from inadvertent use of bromide instead of citrate at the pharmacy, illustrates the importance of knowing common interferents with analyte methodologies and of pursing logical additional diagnostic tests based on clinical and laboratory evidence, even when a patient's history appears to rule out a potential etiology.     

Association of hyponatremia and hyperglycemia with outcome in dogs with congestive heart failure

Objective: To evaluate plasma sodium and glucose concentrations in dogs with congestive heart failure (CHF) prior to treatment and evaluate the differences between survivors and non‐survivors. Design: Retrospective study. Animals: Fifty‐nine dogs with CHF prior to receiving cardiac medication. Interventions: None. Measurements and main results: The mean plasma sodium concentration in dogs with CHF was below the reference range (144–156 mmol/L) and significantly lower (P=0.009) in non‐survivors (141±6 mmol/L) compared with survivors (147±4 mmol/L). The mean plasma glucose concentration was above the reference range (76–117 mg/dL) and significantly higher (P=0.004) in non‐survivors (128±52 mg/dL) compared with survivors (100±13 mg/dL). Forty‐four percent of non‐survivors had concurrent low plasma sodium and high plasma glucose concentrations, whereas no survivors had both abnormalities (P<0.0001). Conclusions: Lower plasma sodium and higher plasma glucose are associated with a worse outcome in dogs with CHF.     

Neonatal respiratory distress and sepsis in the premature foal: Challenges with diagnosis and management

The presentation of a premature, neonatal foal affected with respiratory distress and seizures represents a difficult diagnostic and therapeutic challenge often best addressed by the provision of appropriate emergency care followed by prompt referral to a well‐equipped critical care facility. Veterinary management of the premature foal described in the accompanying report was complicated by the development of sepsis and pulmonary failure. The development of pulmonary emphysematous bullae was identified during the course of the foal's treatment and probably contributed to its clinical deterioration. Diagnostic imaging modalities that may be used for the diagnosis of respiratory distress in neonatal foals include thoracic radiography, ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). Both CT and MRI require general anaesthesia. The likelihood of a successful outcome for the foal in this report might have been improved by the provision of urgent veterinary care and referral to the critical care facility earlier in the course of its management. Important early indicators of the need for urgent veterinary care in this case included the foal's prematurity, inability to stand, and the need to provide manual support to facilitate nursing from the mare's udder. Foals affected in this manner should warrant treatment with broad‐spectrum antimicrobials, circulating volume maintenance, immunoglobulin support, and the use of a nasogastric tube to facilitate nutritional support.     

Use of Renal Replacement Therapy in a Neonatal Foal with Postresuscitation Acute Renal Failure

A newborn foal was presented because it was unresponsive and in cardiopulmonary arrest. Aggressive cardiopulmonary cerebral resuscitation was administered to the foal, which revived the foal; however, acute renal failure developed. Fluid retention and azotemia occurred although the foal was alert and able to suckle. A 6‐hour renal replacement therapy session using hemodiafiltration and a continuous renal replacement therapy machine was administered to the foal at 3 days of age which lowered the foal's azotemia and facilitated removal of some of the excess body fluid. Despite therapy, the foal developed pulmonary edema and was euthanized. Although the foal in this case did not survive, this report highlights the possibility of developing postresuscitation complications such as acute renal failure and describes the use of renal replacement therapy using hemodiafiltration as a viable option in neonatal foals with acute kidney injury.     

Oral Infection of Weanling Foals with an Equine Isolate of Lawsonia intracellularis,Agent of Equine Proliferative Enteropathy

Background: Equine proliferative enteropathy (EPE) is an emerging disease of weanling foals. Objectives: Describe clinical, hematologic, biochemical, serologic, molecular, and ultrasonographic findings in foals experimentally infected with Lawsonia intracellularis. Animals: Eight foals. Methods: Recently weaned foals were assigned to either the challenge (n = 3), the sentinel (n = 3), or the control (n = 2) group. Foals were experimentally challenged via intragastric inoculation of 3 × 10¹⁰L. intracellularis organisms grown in culture. Each experimentally infected foal was housed with a sentinel foal in order to assess feco‐oral transmission. All foals were monitored daily for the development of clinical abnormalities and were weighed once weekly for the duration of the study (90 days). Abdominal ultrasound examination was performed weekly. Feces were collected every other day for 60 days, then weekly for an additional 30 days for the quantitative molecular detection of L. intracellularis. Blood was collected weekly for hematologic, biochemical, and serologic analysis. Results: Only challenged foals developed transient clinical signs of EPE consisting of anorexia, lethargy, fever, loose feces, and peripheral edema. Two challenged foals developed transient hypoalbuminemia. Fecal shedding of L. intracellularis was first detected in the challenged foals between days 12 and 18 postinoculation and lasted for 7–21 days. Seroconversion was documented in all challenged foals and in 1 sentinel foal. The remaining sentinel and control foals remained unaffected. Conclusions and Clinical Importance: Clinical EPE of variable severity was induced in all foals infected with L. intracellularis. Furthermore, L. intracellularis can be transmitted via the feco‐oral route to susceptible herdmates.     

Blood glucose concentrations in critically ill neonatal foals

Reasons for Performing Study: Critical illness is associated with hyperglycemia in humans, and a greater degree and duration of hyperglycemia is associated with nonsurvival. Hypoglycemia is also seen in critically ill humans, and is associated with nonsurvival. This might also be true in the critically ill foal.
Objectives: To investigate the association of blood glucose concentrations with survival, sepsis, and the systemic inflammatory response syndrome (SIRS).
Methods: Blood glucose concentrations at admission (515 foals) and 24 hours (159 foals), 36 hours (95), 48 hours (82), and 60 hours (45) after admission were analyzed. Logistic regression analyses were performed to investigate the association of glucose concentrations with survival, sepsis, a positive blood culture, or SIRS.
Results: 29.1% of foals had blood glucose concentrations within the reference range (76–131 mg/dL) at admission, 36.5% were hyperglycemic, and 34.4% were hypoglycaemic. Foals that did not survive to hospital discharge had lower mean blood glucose concentrations at admission, as well as higher maximum and lower minimum blood glucose concentrations in the 1st 24 hours of hospitalization, and higher blood glucose at 24 and 36 hours. Foals with blood glucose concentrations <2.8 mmol/L (50 mg/dL) or >10 mmol/L (180 mg/dL) at admission were less likely to survive. Hypoglycemia at admission was associated with sepsis, a positive blood culture, and SIRS.
Conclusions and Potential Relevance: Derangements of blood glucose concentration are common in critically ill foals. Controlling blood glucose concentrations may therefore be beneficial in the critically ill neonatal foal, and this warrants further investigation.     

Plasma biochemistry reference values of wild bonnethead sharks,Sphyrna tiburo

Background — Elasmobranchs (sharks, skates, and rays) are of commercial, sport, research, and exhibit importance, however, blood chemistry reference values have been determined for few of these species. Objectives — The purpose of this study was to establish plasma biochemistry and PCV reference values for wild bonnethead sharks (Sphyrna tiburo). Methods — Heparinized blood samples were collected from 24 bonnethead sharks at the time of capture in trawl nets off the coast of South Carolina and Georgia. Weight, length, PCV, total solids (TS, by refractometry), and plasma biochemical analyses were done using standard techniques. Wilcoxon rank‐sum and Kendall tau b tests were used to compare values by animal size, boat and sex; 1–way ANOVA was used to compare TS and total protein (TP) concentrations. Results — Median (quartiles; minimum‐maximum) values were as follows: PCV 22% (22%, 26%; 17–28%), TS 6.3 (6.0, 6.8; 5.8–7.5) g/dL, total protein 2.9 (2.7,3.4; 2.2–4.3) g/dL, albumin 0.4 (0.4,0.4; 0.3–0.5) g/dL, globulins 2.6 (2.3,3.0; 1.9–3.8) g/dL, sodium 282 (279, 285; 273–292) mmol/L, potassium 7.3 (6.4, 7.9; 5.7–9.2) mmol/L, chloride 290 (285, 296; 277–304) mmol/L, total CO₂ 3 (2, 4; 0–5) mmol/L, calcium 16.8 (16.2,17.4; 15.8–18.2) mg/dL, phosphorus 8.8 (7.5,10.0; 5.9–12.7) mg/dL, urea nitrogen 1004 (986, 1028; 944–1068) mg/dL, creatinine <0.1 mg/dL, glucose 184 (165, 191; 155–218) mg/dL, aspartate aminotransferase 42 (33, 66; 15–132) U/L, lactate dehydrogenase <5 U/L, creatine kinase 82 (47, 233; 18–725) U/L, and osmolality 1094 (1078,1111; 1056–1139) mOsm/kg. No differences based on sex were detected. TS and total TP values were related by the fitted line TS = (1.006 × TP) + 3.318. Conclusions — Values reported here will be useful for evaluating the health status of bonnetheads in wild and captive research conditions and in exhibits.     

Retrospective Evaluation of the Effect of Heart Rate on Survival in Dogs with Atrial Fibrillation

Background

Atrial fibrillation (AF) usually is associated with a rapid ventricular rate. The optimal heart rate (HR) during AF is unknown.

Hypothesis/Objectives

Heart rate affects survival in dogs with chronic AF.

Animals

Forty‐six dogs with AF and 24‐hour ambulatory recordings were evaluated.

Methods

Retrospective study. Holter‐derived HR variables were analyzed as follows: mean HR (meanHR, 24‐hour average), minimum HR (minHR, 1‐minute average), maximum HR (maxHR, 1‐minute average). Survival times were recorded from the time of presumed adequate rate control. The primary endpoint was all‐cause mortality. Cox proportional hazards analysis identified variables independently associated with survival; Kaplan‐Meier survival analysis estimated the median survival time of dogs with meanHR <125 bpm versus ≥125 bpm.

Results

All 46 dogs had structural heart disease; 31 of 46 had congestive heart failure (CHF), 44 of 46 received antiarrhythmic drugs. Of 15 dogs with cardiac death, 14 had CHF. Median time to all‐cause death was 524 days (Interquartile range (IQR), 76–1,037 days). MeanHR was 125 bpm (range, 62–203 bpm), minHR was 82 bpm (range, 37–163 bpm), maxHR was 217 bpm (range, 126–307 bpm). These were significantly correlated with all‐cause and cardiac‐related mortality. For every 10 bpm increase in meanHR, the risk of all‐cause mortality increased by 35% (hazard ratio, 1.35; 95% CI, 1.17–1.55; P < 0.001). Median survival time of dogs with meanHR<125 bpm (n = 23) was significantly longer (1,037 days; range, 524‐open) than meanHR ≥125 bpm (n = 23; 105 days; range, 67–267 days; P = 0.0012). Mean HR was independently associated with all‐cause and cardiovascular mortality (P < 0.003).

Conclusions and Clinical Importance

Holter‐derived meanHR affects survival in dogs with AF. Dogs with meanHR <125 bpm lived longer than those with meanHR ≥ 125 bpm.     

Serum chemistry reference values in free‐ranging North Atlantic male walruses (Odobenus rosmarus rosmarus) from the Svalbard archipelago

Background: Information regarding health and disease is limited for walruses, a keystone species in arctic marine ecosystems. Serum chemistry analysis is a useful clinical tool for the health assessment of walruses, but only a few captive Pacific walruses have been evaluated. Objectives: The aim of this study was to determine serum chemistry reference values for free‐ranging male Atlantic walruses (Odobenus rosmarus rosmarus) on Svalbard and to assess potential differences in animals with low and high tissue levels of organic pollutants. Methods: Blood samples were collected from 17 wild, adult, male Atlantic walruses chemically immobilized with etorphine at eastern Svalbard (Norway). Serum was obtained for routine biochemical analysis as well as nonesterified free fatty acids (NEFA) and cortisol tests. Serum protein concentration was also measured by agarose gel electrophoresis. Results: Reference values (ranges) included alanine aminotransferase (12–51 U/L), aspartate aminotransferase (54–137 U/L), alkaline phosphatase (42–243 U/L), creatine kinase (32–506 U/L), lactate dehydrogenase (480–1322 U/L), amylase (0–23 U/L), lipase (68–298 U/L), total protein (68–91 g/L), albumin (25.3–34.8 g/L), creatinine (84–137 μmol/L), urea (8.2–19.9 mmol/L), bilirubin (0–4 μmol/L), cholesterol (4.4–7.3 mmol/L), NEFA (0.1–0.4 mmol/L), triglycerides (0.6–2.2 mmol/L), calcium (2.0–2.7 mmol/L), phosphorus (1.7–2.8 mmol/L), sodium (147–162 mmol/L), potassium (4.7–7.4 mmol/L), chloride (102–115 mmol/L), and cortisol (<28–214 nmol/L). Walruses exposed to high levels of organic pollutants (n=6) had significantly lower (P=.022) phosphorus concentration than those with low levels of pollutants (n=6). Conclusions: The clinical chemistry reference values determined in this study can serve as baseline data for future health‐related studies of walruses in a changing Arctic and may also be helpful for health evaluations of walruses in captivity. Impacts of the exposure of marine mammals to organic pollutants should be further investigated.     

Pelger-Huët anomaly in an Arabian horse

Abstract Abstract: A 9‐year‐old Arabian mare was evaluated for a 7‐day history of malaise. Results of a CBC included a leukocyte concentration within the reference interval (8.4 × 10³/μL, reference interval 6.0–14.0 × 10³/μL) with an apparent degenerative left shift (segmented neutrophils 1.2 × 10³/μL, reference interval 2.5–7.5 × 10³/μL; hyposegmented neutrophils 1.8 × 10³/μL, reference interval 0.0–0.2 × 10³/μL). Serum clinical chemistry results included increased aspartate transaminase, alkaline phosphatase, and gamma‐glutamyltransferase activities. A presumptive diagnosis of hepatitis or cholangiohepatitis was made. The horse was treated with antimicrobials and the malaise quickly resolved. However, in a recheck CBC on day 13, the apparent degenerative left shift remained. Further evaluation of the blood smear revealed many hyposegmented granulocytes with coarse mature chromatin and normal cytoplasmic features. On the basis of the microscopic examination, the horse was diagnosed with Pelger‐Huët anomaly. The patient's offspring was subsequently also diagnosed with Pelger‐Huët anomaly on the basis of blood film examination. Neutrophil, eosinophil, and basophil mean nuclear scores in both affected horses (mare, range 1.5–2.6; offspring, range 1.6–3.2) were lower than those in 2 unrelated Arabian horses (range, 2.8–5.0) and 5 non‐Arabian control horses (range, 2.8–5.0). Results of immunophenotyping and phagocytosis/oxidative burst assays via flow cytometry showed no difference in the expression of myeloid–specific or adhesion molecules or in neutrophil function between affected and control horses. This is the second known report of equine Pelger‐Huët anomaly, both of which affected Arabian horses.     

Serum biochemical reference intervals for wild dwarf ornate wobbegong sharks (Orectolobus ornatus)

Background: Sharks are important to sport and commercial fishing, public aquaria, and research institutions. However, serum biochemical reference values have been established for few species. Objective: The aim of this study was to establish serum biochemical reference intervals for wild‐caught dwarf ornate wobbegong sharks (Orectolobus ornatus). Methods: Fifty wobbegongs were caught, and their health status, sex, length, and weight were evaluated and recorded. Following collection of blood, serum biochemical analytes were measured and analyzed using standard analytical and statistical methods. Combined samples generated means, medians, and reference intervals. Results: For the measured analytes, means (reference intervals) were as follows: sodium 287 (284–289) mmol/L, chloride 277 (274–280) mmol/L, potassium 5.2 (5.0–5.3) mmol/L, total calcium 4.6 (4.5–4.7) mmol/L, magnesium 1.9 (1.7–2.0) mmol/L, inorganic phosphate 1.8 (1.7–1.9) mmol/L, glucose 2.6 (2.4–2.8) mmol/L, total protein 46 (45–47) g/L, urea 396 (392–401) mmol/L, creatinine ≤0.02 mmol/L, total bilirubin 2.0 (1.9–2.1) μmol/L, cholesterol 1.3 (1.2–1.4) mmol/L, triglyceride 0.5 (0.4–0.6) mmol/L, alkaline phosphatase 24 (21–28) U/L, alanine aminotransferase 3 U/L, aspartate aminotransferase 28 (25–31) U/L, creatine kinase 49 (38–59) U/L, and osmolarity 1104 (1094–1114) mmol/L. Serum values were not affected by sex, length, or weight. Conclusions: Established reference values will assist with clinical evaluation and treatment of dwarf ornate wobbegongs in aquaria, research institutions, and the wild.     

Single stage urethroplasty for perineal hypospadias in a foal

The incidence of hypospadias is increasing in man, but the condition is rarely reported in horses. There are few available data regarding the surgical management of this disorder in horses, with no previous published report of urethral reconstructive surgery and only two reports documenting phallectomy procedures. This case report documents hypospadias repair, not previously reported in the horse, in a Thoroughbred foal with proximal hypospadias. The indication for surgery was contact dermatitis of the hind leg, which was impairing the foal's ambulation and had the potential to impair the foal's racing ability. Preoperative examination revealed a proximal hypospadias with a wide urethral plate. The anus was normal. The foal was otherwise thriving. A single stage urethroplasty was performed, during which the urethral plate was tubularised in two layers and the urethral meatus was successfully relocated distally to open upon the glans. The urethroplasty was covered with dartos fascia and the penile shaft skin and prepuce were reconstructed. Minor superficial dehiscence of the wound was successfully managed conservatively. Post‐operatively, urine was voided through the opening created on the glans penis, resolving the contact dermatitis. Follow‐up after 3 years confirmed that the horse continues to void through the re‐sited meatus without complication and had gone on to race successfully. In conclusion, we present the first report of reconstructive urethroplasty for the treatment of a horse for proximal hypospadias with good functionality and long‐term outcome.     

Plasma biochemistry reference values of wild-caught southern stingrays (Dasyatis americana).

Stingrays are prominent marine animals; however, there are few published reference values for their blood chemistry and hematology. Twenty-eight southern stingrays (Dasyatis americana) were caught using the bottom trawl nets of fishery-independent boats operated by the South Carolina Department of Natural Resources during June and July 2002 from Winyah Bay, South Carolina, to St. Augustine, Florida. Median values of blood and plasma obtained from live animals promptly after capture are as follows: packed cell volume = 0.22 L/L (22%), total solids (TS) = 56.5 g/L (5.65 g/dl), total protein (TP) = 26 g/L (2.6 g/dl), sodium = 315 mmol/L, potassium = 4.95 mmol/L, chloride = 342 mmol/L, calcium = 4.12 mmol/L (16.5 mg/dl), phosphorus = 1.5 mmol/L (4.7 mg/dl), urea nitrogen = 444 mmol/L (1,243 mg/dl), glucose = 1.69 mmol/L (30 mg/dl), aspartate aminotransferase = 14.5 U/L, creatine phosphokinase = 80.5 U/L, osmolality = 1065 mOsm/kg, and lactate = 3.1 mmol/L. Bicarbonate was less than the low end of the instrument range (5 mmol/L) in all but three samples. Anion gap was negative in all samples. Albumin was less than the low end of the instrument range (1 g/dl) in all except one sample. Osmolality was significantly higher in the rays caught in the southern region. TS and TP values were linearly related to each other, and the equation for the fitted line is TS = (11.61 x TP) + 25.4 (in g/L) [or TS = (1.161 x TP) + 2.54 (in g/dl)]. The reference ranges reported in this study can be used to aid in the management of aquarium stingrays and to create a baseline for health monitoring of the wild Dasyatis spp.     

Presumptive increase in protein‐bound serum calcium in a dog with multiple myeloma

Abstract: An 11‐year‐old male castrated Australian Shepherd was presented with a history of lethargy, panting, and weight loss for 1 month. Physical examination revealed a moderately enlarged spleen. Laboratory abnormalities included thrombocytopenia and marked hypercalcemia, with hyperglobulinemia, hypoalbuminemia, and a monoclonal spike in the β‐globulin region on serum protein electrophoresis. Serum total calcium concentration was markedly increased (16.5 mg/dL, reference interval 8.9–11.4 mg/dL) but ionized calcium concentration (1.39 mmol/L) was within the reference interval (1.25–1.45 mmol/L). Isosthenuria was noted, but the dog was not polyuric or polydipsic. Serum parathyroid hormone concentration was within reference limits and parathyroid hormone‐related peptide concentration was 0 pmol/L. Radiographic findings were largely unremarkable. Results of cytologic evaluation of a fine‐needle aspirate specimen from the spleen indicated plasma cell neoplasia. Based on the results of the electrophoresis, splenic aspirates, radiographs, and hypercalcemia, a diagnosis of splenic multiple myeloma was made. The marked hypercalcemia, normal ionized calcium and parathyroid hormone concentrations, and lack of osteolytic lesions indicated a presumptive increase in protein‐bound serum calcium, likely due to binding to molecules of the paraprotein (M protein). Protein binding of calcium in dogs with multiple myeloma should be considered as a potential mechanism of elevated total serum calcium concentration.     

The pharmacokinetics of glycopyrrolate in Standardbred horses

The disposition of plasma glycopyrrolate (GLY) is characterized by a three‐compartment pharmacokinetic model after a 1‐mg bolus intravenous dose to Standardbred horses. The median (range) plasma clearance (Clp), volume of distribution of the central compartment (V₁), volume of distribution at steady‐state (Vss), and area under the plasma concentration–time curve (AUC_0‐inf) were 16.7 (13.6–21.7) mL/min/kg, 0.167 (0.103–0.215) L/kg, 3.69 (0.640–38.73) L/kg, and 2.58 (2.28–2.88) ng*h/mL, respectively. Renal clearance of GLY was characterized by a median (range) of 2.65 (1.92–3.59) mL/min/kg and represented approximately 11.3–24.7% of the total plasma clearance. As a result of these studies, we conclude that the majority of GLY is cleared through hepatic mechanisms because of the limited extent of renal clearance of GLY and absence of plasma esterase activity on GLY metabolism. Although the disposition of GLY after intravenous administration to Standardbred horses was similar to that in Thoroughbred horses, differences in some pharmacokinetic parameter estimates were evident. Such differences could be attributed to breed differences or study conditions. The research could provide valuable data to support regulatory guidelines for GLY in Standardbred horses.     

A comparison of noninvasive cardiac output measurement by partial carbon dioxide rebreathing with the lithium dilution technique in anesthetized foals

Newer techniques for cardiac output (Q) determinations that are minimally invasive remain to be validated in neonatal foals against other accepted techniques such as the lithium technique (LiDCO). This study compares Q determinations using the partial CO₂ rebreathing technique (NICO) with LiDCO in anesthetized neonatal foals. Ten foals were instrumented for NICO and LiDCO determinations. For each foal low, intermediate and high levels of cardiac output were achieved in that order using an end‐tidal isoflurane (ETI) concentration of 1.3 – 2.1% for the lowest rate; an ETI of 0.85–1.4% and a constant‐rate infusion of dobutamine (1–3 ?g/kg/min) for the intermediate rate; and an ETI of 0.83–1% and dobutamine (2–6 ?g/kg/min) for the highest rate. Four foals also received IV intermittent doses (total cumulative dose of 1.1–1.7 mg) of phenylephrine at the highest rate of Q. The measurements were obtained in duplicate or triplicate for each Q technique after achieving a stable hemodynamic plane for at least 15 minutes at each rate of Q. For the lithium technique, all foals received 1.1–1.9 mL (0.16–0.28 mmol) of lithium. A Bland‐Altman analysis was used to compare the bias and precision of the two techniques. Eighty seven comparisons were determined between the two techniques. Eight were excluded due to more than 20% variation between the LiDCO determinations or technical errors at the time of determination. The correlation coefficient between the two methods was 0.67 for all Q determinations. Mean LiDCO and NICO values from 79 measurements were 130 ± 40 mL^–1 kg minute^–1 (range, 68– 237) and 152 ± 31 mL^–1 kg minute^–1 (89 – 209), respectively. The mean ( mL^–1 kg minute^–1) of the differences of LiDCO – NICO was = –0.7248 + 0.8602 NICO. The precision (1.96 SD) of the differences between LiDCO and NICO was 58.9 mL^–1 kg minute^–1 (–80.9–+36.9) with a mean difference of –22 mL^–1 kg minute^–1 (bias; 95% CI – 15.2 to ‐28.7). In conclusion, given the small bias compared to the limits of agreement, the NICO technique for determining Q deserves further consideration for adoption into clinical practice in neonatal foals.     

Iatrogenic magnesium overdose: 2 case reports

Objective: To describe the clinical manifestations and treatment of hypermagnesemia and the potential drug errors that can lead to iatrogenic electrolyte toxicities. Summary: We report 2 cases of iatrogenic intravenous (IV) magnesium (Mg) overdose. Both cases developed extreme cardiovascular and neurologic symptoms consisting of vomiting, hypotension, bradycardia, flaccid paralysis, and severe mental depression. Diagnosis was made based upon serum ionized Mg levels (3.47 mmol/L; reference range: 0.43–0.58 mmol/L for Case #1; and 4.64 mmol/L; reference range: 0.42–0.55 mmol/L for Case #2). Each animal was treated with 0.9% NaCl for diuresis and IV calcium gluconate. Within 24 hours, the cardiovascular and neurologic status of both animals, as well as the serum Mg concentration, had normalized. Each animal was discharged with no complications. Both animals had been hospitalized for critical illness and had developed hypomagnesemia that was being treated with Mg sulfate infusions. The cause for the hypermagnesemia was due to miscalculations in treatment orders that led to erroneously administered Mg‐containing solutions. Confusing drug labels and varying units of measurement can lead to erroneous miscalculations, especially in critically ill patients that receive multiple IV infusions. New information provided: This is the first case report of iatrogenic Mg overdose in veterinary medicine. These 2 cases had a good clinical outcome with prompt recognition and supportive care.