Insulin, glucagon, and leptin in critically ill foals

Background: Endocrine dysregulation of hormones of energy metabolism is well documented in critically ill humans, but limited information exists in septic foals. The purpose of this study was to provide information on the hormonal response to energy metabolism in critically ill foals, focusing on insulin, glucagon, and leptin. Hypothesis: Concentrations of insulin, glucagon, leptin, and triglycerides will be higher, whereas glucose concentration will be lower in septic foals than in healthy and sick nonseptic foals. The magnitude of these differences will be associated with severity of disease and nonsurvival. Animals: Forty‐four septic, 62 sick nonseptic, and 19 healthy foals <7 days of age. Methods: In this prospective multicenter cross‐sectional study, blood samples were collected at admission. Foals with positive blood culture or sepsis score ≥12 were considered septic. Results: Septic foals had lower glucose and insulin and higher triglyceride and glucagon concentrations than did healthy foals. Glucagon concentrations were not different between septic foals that died (n = 14) or survived (n = 30). Higher insulin and lower leptin concentrations were associated with mortality. Quantitative insulin‐sensitivity check index was higher in septic foals. Conclusions and Clinical Importance: Energy metabolism and the endocrine response of related hormones in septic foals are characterized by hypoglycemia, hypertriglyceridemia, low insulin concentration, and high glucagon concentration. Leptin and insulin may have prognostic value for nonsurvival in septic foals. The hormonal response related to energy metabolism in critical illness differs between foals and humans.     

Calcium Regulating Hormones and Serum Calcium and Magnesium Concentrations in Septic and Critically Ill Foals and their Association with Survival

Background: Disorders of calcium regulation are frequently found in humans with critical illness, yet limited information exists in foals with similar conditions including septicemia. The purpose of this study was to determine whether disorders of calcium exist in septic foals, and to determine any association with survival.
Hypothesis: Blood concentrations of ionized calcium (Ca²⁺) and magnesium (Mg²⁺) will be lower in septic foals with concomitant increases in parathyroid hormone (PTH), calcitonin (CT), and parathyroid-related peptide (PTHrP) compared with healthy foals. The magnitude of these differences will be negatively associated with survival.
Animals: Eighty-two septic, 40 sick nonseptic, and 24 healthy foals of ≤7 days were included.
Methods: Prospective, observational study. Blood was collected at initial examination for analysis. Foals with positive blood culture or sepsis score ≥14 were considered septic. Foals with disease other than sepsis and healthy foals were used as controls. Hormone concentrations were measured with validated immunoassays.
Results: Septic foals had decreased Ca²⁺ (5.6 versus 6.1 mg/dL, P < .01) and increased serum PTH (16.2 versus 3.2 pmol/L, P < .05), and phosphorus concentrations (7.1 versus 6.3 mg/dL, P < .01). No differences in serum Mg²⁺, PTHrP, and CT concentrations were found. Nonsurviving septic foals (n = 42/82) had higher PTH concentrations (41.1 versus 10.7 pmol/L, P < .01) than survivors (n = 40/82).
Conclusions and Clinical Importance: Septic foals were more likely to have disorders of calcium regulation compared with healthy foals, where hyperparathyroidemia was associated with nonsurvival.     

Blood arginine vasopressin, adrenocorticotropin hormone, and cortisol concentrations at admission in septic and critically ill foals and their association with survival

BACKGROUND: Sepsis is an important cause for neonatal foal mortality. The hypothalamic-pituitary-adrenal axis (HPAA) responses to sepsis are well documented in critically ill humans, but limited data exist in foals. The purpose of this study was to evaluate the HPAA response to sepsis in foals, and to associate these endocrine changes with survival. HYPOTHESIS: Blood concentrations of arginine vasopressin (AVP), adrenocorticotropin hormone (ACTH), and cortisol will be higher in septic foals as compared with sick nonseptic and healthy foals. The magnitude of increase in hormone concentration will be negatively associated with survival. ANIMALS: Fifty-one septic, 29 sick nonseptic, and 31 healthy foals of < or =7 days of age were included. METHODS: Blood was collected at admission for analysis. Foals with positive blood culture or sepsis score > or =14 were considered septic. Foals admitted with disease other than sepsis and healthy foals were used as controls. AVP, ACTH, and cortisol concentrations were measured using validated immunoassays. RESULTS: AVP, ACTH, and cortisol concentrations were increased in septic foals. Septic nonsurvivor foals (n = 26/51) had higher plasma ACTH and AVP concentrations than did survivors (n = 25/51). Some septic foals had normal or low cortisol concentrations despite increased ACTH, suggesting relative adrenal insufficiency. AVP, ACTH, and cortisol concentrations were higher in sick nonseptic foals compared with healthy foals. CONCLUSIONS AND CLINICAL IMPORTANCE: Increased plasma AVP and ACTH concentrations in septic foals were associated with mortality. Several septic foals had increased AVP : ACTH and ACTH : cortisol ratios, which indicates relative adenohypophyseal and adrenal insufficiency.     

Prospective Evaluation of Coagulation in Critically Ill Neonatal Foals

Background: Coagulopathy is a potentially underrecognized complication of sepsis and septic shock in critically ill neonatal foals.
Hypothesis: Critically ill neonatal foals have abnormalities in coagulation that are associated with disease severity and outcome.
Animals: Foals <72 hours old admitted to a neonatal intensive care unit.
Methods: Prospective, observational study. Blood was collected at admission, 24, and 48 hours for platelet count, prothrombin time, activated partial thromboplastin time, antithrombin activity and concentrations of fibrin degradation products, and fibrinogen in plasma from all foals.
Results: Sixty-three foals were enrolled and classified as Septic Shock (12), Septic (28), and Other (23). At least 1 abnormal value was found in 18/28 (64%) samples from the Septic Shock group, 66/85 (78%) from the Septic group, and 30/59 (51%) from the Other group ( P = .01). Coagulopathy (3 or more abnormal values) was present in 7/28 (25%) samples in the Septic Shock group, 14/85 (16%) samples in the Septic group, and 3/59 (5%) samples in the Other group ( P = .0028). Clinically detectable bleeding occurred in 8/12 (67%) Septic Shock cases, 11/28 (39%) Septic cases, and 3/23 (13%) Other cases ( P = .009). Foals in Septic Shock were 12.7 times more likely to have clinical evidence of bleeding than those in the Other group (95% CI 2.3–70, P = .004). Treatment with fluids or plasma did not have a detectable effect on coagulation values.
Conclusions and Clinical Importance: Coagulopathy commonly occurs in critically ill neonatal foals, especially those with sepsis and septic shock.     

Factors associated with outcome in foals with neonatal isoerythrolysis (72 cases, 1988-2003)

Background: Neonatal foals with isoerythrolysis (NI) often die, but the risk factors for death have not been identified.
Objectives: To identify factors associated with outcome in foals with NI and to identify factors associated with death from liver failure or kernicterus in the same population.
Animals: Seventy-two foals with NI examined at referral institutions.
Methods: Retrospective case series. Information on signalment, clinical examination findings, laboratory testing, treatment, complications, outcome, and necropsy results were obtained.
Results: The overall survival rate was 75% (54 of 72). Liver failure (n = 7), kernicterus (n = 6), and complications related to bacterial sepsis (n = 3) were the 3 most common reasons for death or euthanasia. The number of transfusions with blood products was the factor most strongly associated with nonsurvival in a multivariate logistic regression model. The odds of liver failure developing in foals receiving a total volume of blood products ≥ 4.0 L were 19.5 (95% confidence intervals [CI]: 2.13–178) times higher than that of foals receiving a lower volume ( P = .009). The odds of kernicterus developing in foals with a total bilirubin ≥ 27.0 mg/dL were 17.0 (95% CI: 1.77–165) times higher than that of foals with a lower total bilirubin ( P = .014).
Conclusions and Clinical Importance: Development of liver failure, kernicterus, and complications related to bacterial sepsis are the most common causes of death in foals with NI. Foals administered a large volume of blood products are at greater risk for developing liver failure.     

Arterial lactate concentration, hospital survival, sepsis and SIRS in critically ill neonatal foals

REASONS FOR PERFORMING STUDY: Blood lactate concentration has been shown to be a useful clinical indicator in human patients, but has not been formally investigated in critically ill foals. OBJECTIVE: To investigate the association of blood lactate with hospital survival, markers of cardiovascular status, metabolic acid base status, sepsis and systemic inflammatory response syndrome (SIRS). METHODS: A database containing clinical, haematological, plasma biochemical and hospital outcome data on neonatal foals referred to an intensive care unit in 2000-2001 was analysed. Seventy-two foals for which arterial lactate was measured at admission were included in the study. RESULTS: Sixty-one foals had an admission lactate concentration > 2.5 mmol/l. Admission lactate was statistically associated with hospital survival, mean arterial pressure, blood creatinine concentration, bacteraemia, anion gap, lactate concentration at 18-36 h after admission and evidence of SIRS, but not with packed cell volume or heart rate. Lactate at 18-36 h was also associated with survival and evidence of SIRS. Anion gap, base excess, base excess due to unidentified anions (BEua), simplified strong ion gap or bicarbonate correctly classified foals for presence of hyperlactaemia (> 5 mmol/l) in < or = 80% of animals. CONCLUSIONS: Admission blood lactate gives important prognostic information. Lactate should be measured rather than assumed from the anion gap, base excess, BEua, simplified strong ion gap or bicarbonate. POTENTIAL RELEVANCE: Blood lactate concentrations at admission are clinically relevant in neonatal foals and warrant further investigation. This should include the clinical value of measuring changes in lactate in response to treatment.     

Comparison of viscoelastic coagulation analysis and standard coagulation profiles in critically ill neonatal foals to outcome

Objective – To determine if changes in viscoelastic variables are associated with abnormalities observed in the standard coagulation profile and patient outcome in foals with suspected septicemia. Design – Prospective clinical trial during 2003 and 2004 foal season. Setting – Neonatal intensive care unit at a veterinary teaching hospital. Animals – Thirty critically ill foals <72‐hour‐old admitted sequentially meeting criteria for systemic inflammatory response associated with infection. Interventions – Hemostatic evaluation, using standard coagulation testing and viscoelastic analysis, was performed at admission, 24 hours following admission, and 48 hours following admission in critically ill foals. Standard coagulation tests included platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin(ogen) degradation products, and antithrombin. Data collected from viscoelastic analysis included time to initial clot formation (ACT), clot rate, and platelet function. Signalment, blood culture results, clinicopathologic data, and outcome were collected from medical records. Equality of populations test was used to determine associations between coagulation tests and blood culture status/outcome, as well as between viscoelastic parameters and coagulopathy, blood culture status, and outcome. Logistic regression was used to quantify associations. A significance level of P<0.05 was used. Measurements and Main Results – Foals with decreasing clot rate (CR) over the sample period were more likely to be euthanized or die (P=0.02). Foals with prolonged ACT (P=0.03), and decreased CR at admission (P=0.047), were more commonly coagulopathic. Identification of coagulopathy on admission (P=0.02), or persistence of hemostatic dysfunction 48 hours later (P=0.04), was associated with death. Conclusions – Viscoelastic coagulation evaluation could be used in a neonatal intensive care unit setting to further characterize coagulopathy, and identify foals at higher risk for poor outcome.     

Association between Hyperglycemia and Survival in 228 Horses with Acute Gastrointestinal Disease

Background: Glucose homeostasis is dysregulated in critically ill humans resulting in hyperglycemia and decreased survival. Hyperglycemia is common in horses presenting with abdominal crisis, and this might be associated with a worse prognosis for survival.
Objective: To determine if hyperglycemia in horses with acute abdominal disease is associated with increased odds of failure to survive to hospital discharge.
Animals: Two hundred and twenty-eight adult horses with acute gastrointestinal disease.
Methods: Observational retrospective study. Records of horses > 1 year of age presenting for treatment of colic over a 3-year period were reviewed. Data collected included age, duration of colic, glucose, heart rate, PCV, total protein, anion gap, cost of hospitalization, breed, sex, pain at admission, diagnosis, whether surgery was performed, and life status at hospital discharge. Potential risk factors for nonsurvival were screened by univariable logistic regression and the best-fitting univariable model was used as the basis for multivariable regression modeling.
Results: Mean blood glucose was 155 mg/dL (8.5 mM) with 45% of the population above the reference range; 16.7% (38 of 228) of horses had severe hyperglycemia (>195 mg/dL; 10.7 mM). Factors associated with increased odds of failure to survive included glucose, severity of pain at admission, heart rate, PCV, anion gap, and diagnosis. The best-fitting multivariable model included glucose and diagnosis, with age included as a confounding variable. The model correctly classified outcome for 92.5% of horses.
Conclusions and Clinical Importance: This study has confirmed prior reports that hyperglycemia is common in horses with colic and is associated with a worse prognosis for survival to hospital discharge.     

Ionized Hypocalcemia in Critically Ill Dogs

Background: Ionized hypocalcemia (iHCa) is a common electrolyte disturbance in critically ill people, especially those with sepsis. The cause of the iHCa is not entirely understood and is likely multifactorial. Critically ill people with iHCa have longer hospital stays and higher mortality rates compared to people with normocalcemia. There are no published clinical studies evaluating the incidence and impact of iHCa in critically ill dogs.
Hypothesis: iHCa occurs in critically ill dogs, is more prevalent in dogs with systemic inflammatory response syndrome (SIRS) or sepsis, and is associated with longer hospital stays and higher mortality.
Animals: One hundred and forty-one client-owned dogs admitted to a companion animal intensive care unit (ICU) in a veterinary teaching hospital.
Methods: Prospective observational study of sequentially enrolled dogs. Blood was collected and analyzed within an hour of admission from all dogs presented to the ICU that met study inclusion criteria.
Results: The incidence of iHCa (iCa < 1.11 mmol/L) was 16%. The presence of iHCa was associated with longer ICU ( P = .038) and hospital ( P = .012) stays but not with decreased survival ( P = .60). Dogs with sepsis as defined by ≥3 SIRS criteria and a positive culture were more likely to have iHCa ( P = .050).
Conclusions and Clinical Relevance: In dogs not previously treated with fluids or blood products intravenously, the finding of iHCa upon admission to the ICU predicted a longer duration of ICU and hospital stay. Septic dogs with positive cultures were more likely to have iHCa.     

Plasma adrenocorticotropin, cortisol, and adrenocorticotropin/cortisol ratios in septic and normal-term foals

BACKGROUND: Little information exists on the hypothalamic-pituitary-adrenal axis in septic foals. HYPOTHESIS: The plasma concentrations of adrenocorticotropin (ACTH) and cortisol are expected to be higher in septic foals as compared to normal foals. The concentrations of hormones in septic foals also are expected to differ further depending upon survival. ANIMALS: Twenty-eight control foals and 46 septic foals <14 days of age were included in this study. METHODS: Blood was collected in EDTA once from 28 normal foals born in the University of Georgia or Cornell University equine research herds and from 46 septic foals within 12 hours after admission to 1 of the 3 tertiary care referral centers involved in the study. Septic foal selection was based on a sepsis score of >11 or a positive blood culture. The control foals were age matched to the septic foals in the study. ACTH and cortisol concentrations were measured by a chemiluminescent immunoassay system. RESULTS: Cortisol concentrations in control foals did not vary with age. Septic foals had significantly higher mean ACTH, cortisol, and ACTH/cortisol ratios than did normal foals. Within the septic foal group, 28 foals survived to discharge, and 18 were euthanized or died. The mean age was not significantly different between the septic surviving and nonsurviving foals. The mean ACTH/cortisol ratio was significantly higher in the septic nonsurviving foals as compared to the septic surviving foals. CONCLUSIONS AND CLINICAL IMPORTANCE: Septic foals had higher hormone concentrations as compared to normal foals, which is an expected endocrine response to critical illness. The increased ACTH/cortisol ratio in nonsurviving septic foals in comparison to surviving septic foals could indicate hypothalamic-pituitary-adrenal axis dysfunction at the level of the adrenal gland in critically ill septic foals.     

Sequential Plasma Lactate Concentrations as Prognostic Indicators in Adult Equine Emergencies

Background: Sequential lactate concentration ([LAC]) measurements have prognostic value in that hospitalized humans and neonatal foals that have a delayed return to normolactatemia have greater morbidity and case fatality rate.
Hypothesis: Prognosis for survival is decreased in horses with a delayed return to normal [LAC].
Animals: Two hundred and fifty adult horses presented for emergency evaluation excepting horses evaluated because of only ophthalmologic conditions, superficial wounds, and septic synovitis without systemic involvement.
Methods: Prospective observational study. [LAC] was measured at admission and then at 6, 12, 24, 48, and 72 hours after admission. The change in [LAC] over time ([LAC]Δ T ) was calculated from changes in [LAC] between sampling points.
Results: Median [LAC] was significantly ( P < .001) higher at admission in nonsurvivors (4.10 mmol/L [range, 0.60–18.20 mmol/L]) when compared with survivors (1.30 mmol/L [range, 0.30–13.90 mmol/L]) and this difference remained at all subsequent time points. The odds ratio for nonsurvival increased from 1.29 (95% confidence interval 1.17–1.43) at admission to 49.90 (6.47–384) at 72 hours after admission for every 1 mmol/L increase in [LAC]. [LAC]Δ T was initially positive in all horses but became negative and significantly lower in nonsurvivors for the time periods between 24–72 hours (− 0.47, P = .001) and 48–72 hours (− 0.07, P = .032) when compared with survivors (0.00 at both time periods) consistent with lactate accumulation in nonsurvivors.
Conclusions and Clinical Importance: These results indicate that lactate metabolism is impaired in critically ill horses and [LAC]Δ T can be a useful prognostic indicator in horses.     

Efficacy and Safety of a Commercial Fresh-Frozen Hyperimmune Plasma in Foals With Failure of Passive Transfer of Immunity

In foals more than 12 hours old, the only effective therapy for the treatment of failure of passive transfer (FPT) of immunity is transfusion of equine plasma. Use and efficacy of equine plasma for prophylaxis and treatment of sepsis, a condition primarily associated with FPT, are widely reported. However, plasma- and recipient-related factors associated with extent of IgG transfer and catabolism are not completely defined. Efficacy and safety of transfusion of a commercial fresh-frozen hyperimmune plasma were evaluated in hospitalized foals younger than 7 days of age with total or partial FPT. Sixty-two foals, classified as affected by FPT only, septic (infection plus systemic inflammatory response syndrome [SIRS]), and nonseptic sick, were included, and serum IgG concentration was measured at admission and 24 hours after plasma transfusion. In 25/62 foals, IgG level after 72 hours was also determined. The impact of different classification criteria for septic foals on IgG transfer was evaluated. Serum IgG measured 24 hours and 72 hours after plasma transfusion was significantly greater than at admission, but no significant difference was found in transfer efficacy (TE) between FPT, FPT septic, and FPT nonseptic foals and no significant difference was found in IgG concentration comparing foals with total and partial FPT or survivors and nonsurvivors. No significant difference was found comparing IgG concentration between bacteremic and nonbacteremic foals and foals with or without SIRS. No foal experienced adverse reactions to plasma transfusion. IgG TE and catabolism did not result significantly affected by the presence of sepsis or illness or by the outcome.     

Serum lactoferrin and immunoglobulin G concentrations in healthy or ill neonatal foals and healthy adult horses

BACKGROUND: Lactoferrin is a colostral glycoprotein with antimicrobial properties. HYPOTHESES: (1) Serum lactoferrin and immunoglobulin G (IgG) concentrations are correlated and increase in healthy foals after ingestion of colostrum; (2) compared to healthy foals, ill foals will have lower lactoferrin concentrations that correlate with their IgG concentration, neutrophil count, the diagnosis of sepsis, and survival; and (3) plasma concentrations of lactoferrin will be less than serum concentrations. ANIMALS: Healthy foals (n = 16), mature horses (n = 10), and ill foals 1-4 days old (n = 111) that were examined for suspected sepsis were used for blood collection. Colostrum was obtained from 10 healthy mares unrelated to the foals. METHODS: Blood was obtained from the healthy foals at birth and 1-3 days of age and from the ill foals at admission. Serum IgG was quantified by single radial immunodiffusion (SRID). Lactoferrin concentrations in colostrum and blood were determined by an enzyme-linked immunosorbant assay. The sepsis score, blood culture results, neutrophil counts, and survival were obtained on ill foals. RESULTS: The mean colostral lactoferrin concentration was 21.7 microg/mL. Compared to values at birth, serum IgG (18+/-2 versus 2,921+/-245 mg/dL, SEM) and lactoferrin (249+/-39 versus 445+/-63 ng/mL, SEM) concentrations were significantly greater in healthy foals 1-3 days old. Serum lactoferrin concentration in 1-3-day-old healthy foals was not different from mature horses or ill foals. IgG and lactoferrin concentrations were significantly correlated only in healthy foals. Serum lactoferrin concentrations were significantly lower in ill neutropenic foals. The serum IgG concentration was significantly lower in ill foals as compared to healthy foals. Only serum IgG was significantly less in ill foals with a positive sepsis score and in nonsurvivors, Plasma lactoferrin concentrations were lower than serum concentrations, although values were significantly correlated. CLINICAL IMPORTANCE: Although both serum IgG and lactoferrin concentrations increase in healthy foals after ingestion of colostrum, only serum IgG is significantly correlated with the sepsis score and outcome.     

Hypothalamic-Pituitary-Adrenal Axis Dysfunction in Hospitalized Neonatal Foals

Background: Transient hypothalamic-pituitary-adrenal (HPA) axis dysfunction occurs frequently in critically ill humans and impacts survival. The prevalence and impact of HPA axis dysfunction in critically ill neonatal foals are not well characterized.
Hypotheses: (1) HPA axis dysfunction occurs in hospitalized neonatal foals, and is characterized by inappropriately low basal serum cortisol concentration or inadequate cortisol response to exogenous adrenocorticotropic hormone (ACTH); (2) hospitalized foals with HPA axis dysfunction have more severe disease and are less likely to survive than hospitalized foals with normal HPA axis function.
Animals: Seventy-two hospitalized foals and 23 healthy age-matched foals.
Methods: Basal ACTH and cortisol concentrations were measured and a paired low-dose (10 μg)/high-dose (100 μg) cosyntropin stimulation test was performed at admission in hospitalized foals. HPA axis dysfunction was defined as (1) an inappropriately low basal cortisol concentration or (2) an inadequate increase in cortisol concentration (delta cortisol) after administration of cosyntropin, with cut-off values for appropriate basal and delta cortisol concentrations determined from results obtained in healthy age-matched foals.
Results: Forty-six percent of hospitalized foals had an inappropriately low basal cortisol concentration and 52% had an inadequate delta cortisol concentration after administration of the 100 μg dose of cosyntropin. An inadequate delta cortisol response to the high (100 μg) dose of cosyntropin was significantly correlated with shock and multiple organ dysfunction syndrome in hospitalized foals, and with decreased survival in a subgroup of septic foals.
Conclusions and Clinical Importance: HPA axis dysfunction occurs frequently in hospitalized neonatal foals, and negatively impacts disease severity and survival.     

Glucose metabolism in five septic neonatal foals

Objective: Glucose metabolism is often deranged in septic animals. Bacteremia and sepsis are common in foals and clinical experience suggests that glucose metabolism is abnormal in some of these animals. The purpose of this study was to provide initial estimates of rates of glucose appearance, disappearance, and metabolic clearance rate in septic foals.
Series Summary: Rates of glucose entry, and exit from blood were determined by use of infusion of isotopically labeled glucose in 5 foals with confirmed sepsis. Serum concentrations of glucose, insulin, glucagon, and cortisol were measured concurrent with measurement of rates of glucose turnover. Median glucose turnover rate was 24 μmol/kg/min (range 17–53 μmol/kg/min), and median glucose metabolic clearance rate was 3.2 mL/kg/min (range 1.7–6.7 mL/kg/min). Median concentration of serum immunoreactive insulin was 55 pmol/L (range 36–190 pmol/L), median serum immunoreactive glucagon was 65 pmol/L (range 19–120 pmol/L), and median serum cortisol was 207 nmol/L (range 100–333 nmol/L).
New or unique information provided: These data, although limited in scope and by the lack of data in healthy foals, demonstrate the magnitude and variation in glucose appearance, disappearance, and metabolic clearance rate in septic foals, provide an estimate of rates of glucose utilization in sick foals, and will be useful in guiding future studies of energy metabolism in healthy and ill foals.     

Factors Associated with Survival in Septicemic Foals: 65 Cases (1988–1995)

In order to identify variables obtained at admission that could be used to predict survival in septicemic foals, medical records of 65 foals diagnosed with septicemia were reviewed. Initially, variables were analyzed independently (univariate analysis) for association with survival. Of the physical examination and historical data examined using univariate analysis, the ability to stand at admission, respiratory rate ≥ 60 breaths per minute (bpm), and normal-appearing mucous membranes were significantly associated with survival. Foals with history of induced parturition were significantly less likely to survive. The following hematologic and serum biochemical variables determined at admission were significantly associated with survival: white blood cell count a 6,000 cells/μL, neutrophil count <4,000 cells/μL, serum albumin concentration <2.2 g/dL, serum glucose concentration <120 mg/ dL, blood pH ≥ 7.35, and positive base excess. The administration of plasma at admission was significantly associated with survival. Stepwise multiple logistic regression analysis was performed to evaluate the association between survival and variables identified as significantly associated with survival in bivariate analysis. The final multivariate model selected included the variables standing, duration of clinical signs (24-hour intervals) prior to admission, respiratory rate a 60 bpm, neutropenia (> 4,000 cells/μL), and neonatal age category. The probability of survival was significantly increased for foals that were standing, had a respiratory rate a 60 bpm, and that had a neutrophil count <4,000 cells/μL at admission. Probability of survival was significantly decreased for foals that had a longer duration of clinical signs prior to admission. For each 24 hours of duration, the estimated risk of death was increased by 5.8-fold.     

Risk factors and prognostic variables for survival of foals with radiographic evidence of pulmonary disease

The medical records of 163 neonatal foals that had thoracic radiographs taken within 48 hours of admission to a referral hospital were reviewed. The objectives of this study were (1) to identify risk factors for the development of thoracic radiographic changes and (2) to identify prognostic indicators for survival in foals with radiographic evidence of pulmonary disease. Failure of transfer of passive immunity (IgG concentration < or = 400 mg/dL) was the only risk factor for radiographic evidence of respiratory disease identified by multivariate analysis. Hypoxemic patients (PaO2 < or = 60 mm Hg) were 4.9 times more likely to reveal radiographic abnormalities in a subset of foals for which arterial blood gas results were available. Foals with a serum creatinine concentration > 1.7 mg/dL upon presentation, dyspnea, and a history of dystocia were significantly more likely to die based on the multivariate statistical outcome analysis. An anion gap > or = 20 mEq/dL was strongly associated with nonsurvival in a subset of foals with arterial blood gas results. These hematologic and biochemical variables can be readily obtained during the initial evaluation of sick foals. The presence of a high anion gap appeared to have the greatest clinical impact and may be a useful prognostic indicator in foals with radiographic evidence of respiratory disease. In contrast, the majority of physical examination variables, including evaluation of tachypnea, abnormal respiratory sounds, fever, weakness, and milk reflux from the nares, which are usually obtained during the general respiratory evaluation of foals, were unrelated to outcome.     

Association of hyperlactatemia with age,diagnosis, and survival in equine neonates

Objective – To investigate the association between blood lactate concentration, measured at admission and following 12–36 hours of treatment, and age, diagnosis, and survival in neonatal foals. Design – Retrospective, observational study. Setting – Two equine referral hospitals. Animals – One hundred and twelve foals ≤96 hours of age were included. Interventions – Arterial or venous blood samples were obtained from all foals at admission and surviving foals at 12–36 hours. Measurements – The lactate concentration (LAC) was recorded at 2 time points: admission (LAC‐Admission) and 12–36 hours following treatment (LAC‐24 hours). Main Results – LAC decreased by 0.05 mmol/L for each increased hour of age at presentation. Premature/dysmature foals demonstrated increased odds of nonsurvival of 55% for each 1 mmol/L increase in LAC‐Admission while foals with major diagnoses of neonatal encephalopathy (NE), enteritis and ‘Other’ had increased odds of nonsurvival of 52%, 113%, and 247%, respectively, for each 1.0 mmol/L increase in LAC. Blood‐culture positive foals had significantly lower LAC than blood culture negative foals. LAC‐Admission and LAC‐24 hours were significantly larger in nonsurviving foals. LAC‐Admission of >6.9 mmol/L and LAC‐24 hours >3.2 mmol/L, respectively, correctly classified 85.6% and 94.1% of cases as survivors or nonsurvivors. No differences were found when the 24‐hour change in LAC was investigated in terms of outcome, age at admission, or major diagnosis; however, LAC‐24 hours remained significantly associated with survival. Conclusions – Admission or persistent hyperlactatemia is associated with a nonsurvival. Younger foals, premature/dysmature foals, and foals with neonatal encephalopathy had the largest LAC.     

Hypothalamic-Pituitary-Adrenal Axis Assessment in Healthy Term Neonatal Foals Utilizing a Paired Low Dose/High Dose ACTH Stimulation Test

Background: Hypothalamic-pituitary-adrenal (HPA) axis function is dynamic in the neonatal foal. The paired low dose/high dose cosyntropin (ACTH) stimulation test allows comprehensive HPA axis assessment, but has not been evaluated in neonatal foals.
Hypothesis: Foal age will significantly affect cortisol responses to a paired 10 and 100 μg dose cosyntropin stimulation test in healthy neonatal foals.
Animals: Twenty healthy neonatal foals.
Methods: HPA axis function was assessed in 12 foals at birth and at 12–24, 36–48 hours, and 5–7 days of age. At each age, basal cortisol and ACTH concentrations were measured and cortisol responses to 10 and 100 μg cosyntropin were assessed with a paired ACTH stimulation test protocol. Eight additional 36–48-hour-old foals received saline instead of 10 μg cosyntropin in the same-paired ACTH stimulation test design.
Results: At birth, foals had significantly higher basal cortisol and ACTH concentrations and higher basal ACTH : cortisol ratios compared with foals in all other age groups. A significant cortisol response to both the 10 and 100 μg doses of cosyntropin was observed in all foals. The magnitude of the cortisol response to both doses of cosyntropin was significantly different across age groups, with the most marked responses in younger foals. There was no effect of the paired ACTH stimulation test design itself on cortisol responses.
Conclusions and Clinical Importance: A paired 10 and 100 μg cosyntropin stimulation test can be used to evaluate HPA axis function in neonatal foals. Consideration of foal age is important in interpretation of HPA axis assessment.