Relative Adrenal Insufficiency in Dogs with Sepsis

Defining sepsis in small animals

OBJECTIVE

To discuss the definitions of sepsis in human and veterinary medicine.

DESIGN

International, multicenter position statement on the need for consensus definitions of sepsis in veterinary medicine.

SETTING

Veterinary private practice and university teaching hospitals.

ANIMALS

Dogs and cats.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Sepsis is a life-threatening condition associated with the body's response to an infection. In human medicine, sepsis has been defined by consensus on 3 occasions, most recently in 2016. In veterinary medicine, there is little uniformity in how sepsis is defined and no consensus on how to identify it clinically. Most publications rely on modified criteria derived from the 1991 and 2001 human consensus definitions. There is a divergence between the human and veterinary descriptions of sepsis and no consensus on how to diagnose the syndrome. This impedes research, hampers the translation of pathophysiology insights to the clinic, and limits our abilities to optimize patient care. It may be time to formally define sepsis in veterinary medicine to help the field move forward. In this narrative review, we present a synopsis of prior attempts to define sepsis in human and veterinary medicine, discuss developments in our understanding, and highlight some criticisms and shortcomings of existing schemes.

CONCLUSIONS

This review is intended to serve as the foundation of current efforts to establish a consensus definition for sepsis in small animals and ultimately generate evidence-based criteria for its recognition in veterinary clinical practice.

The impact of single-dose trazodone administration on plasma endogenous adrenocorticotropic hormone and serum cortisol concentrations in healthy dogs

BACKGROUND

Conditions affecting the hypothalamic-pituitary-adrenal (HPA) axis are common in dogs. Testing the function of the HPA axis includes measurement of endogenous adrenocorticotropic hormone (eACTH) and performance of an adrenocorticotropic hormone (ACTH) stimulation test. Trazodone is commonly administered to dogs to decrease stress. In humans, trazodone significantly decreases plasma cortisol concentration via alpha-1 adrenergic activity.

OBJECTIVES

Determine the influence of trazodone on eACTH and serum cortisol concentrations in healthy dogs.

ANIMALS

Fourteen healthy, adult, companion dogs.

METHODS

Prospective, randomized placebo-controlled study. Trazodone (8-10 mg/kg) or placebo was administered PO 1 hour before eACTH measurement and ACTH stimulation testing. After a ≥7-day wash-out period, dogs received the opposite treatment. Differences in eACTH, pre- and post-ACTH stimulation cortisol concentrations, and delta (difference between pre- and post-ACTH) cortisol concentrations were analyzed using a paired t or signed-rank test with a P < .05 significance level.

RESULTS

The eACTH concentrations were not significantly different (P = .23) between treatments. Similarly, no significant differences were found in the pre-ACTH cortisol concentrations between treatments (P = .40). Post-ACTH cortisol concentrations (P = .05) and delta cortisol concentrations (P = .04) were significantly lower when the dogs were treated with trazodone.

CONCLUSIONS

Preliminary data suggest trazodone administration dampens the adrenocortical response to stimulation in healthy dogs. If similar effects are found in dogs with adrenal disease, the use of trazodone may affect diagnosis and clinical decision making in these populations.

Evaluation of Resting Serum Bile Acid Concentrations in Dogs with Sepsis

Recent studies in the human literature suggest that serum bile acid concentrations could be an early predictor of short-term survival in critically ill patients. However, there is no available information in the veterinary literature regarding serum bile acid concentrations in dogs with sepsis. We aimed to evaluate if resting serum bile acid concentrations differ between septic and non-septic dogs. This was a retrospective observational study, of medical records at a single referral center over a twelve-year period. Twenty-six client-owned dogs diagnosed with sepsis were identified. Twenty-one dogs presenting with a non-hepatobiliary systemic disease and twenty-nine dogs admitted for an elective orthopedic procedure, considered otherwise healthy, were selected as control groups. Resting serum bile acid concentrations were significantly higher in the septic compared to the non-septic groups (ill control and orthopedic control groups). However, when assessing bile acid concentrations between groups individually, no difference was identified between the septic and the orthopedic control group. These results should be interpreted cautiously.

Corticosteroid treatment for acute/acute-on-chronic experimental and naturally occurring pancreatitis in several species: a scoping review to inform possible use in dogs

Acute pancreatitis in dogs is a prevalent disease characterised by mild to severe inflammation. Treatment with anti-inflammatory corticosteroids has been widely debated but is not generally recommended in veterinary medicine. The objective of the present study was to present current evidence on the effect of corticosteroid treatment for acute/acute-on-chronic pancreatitis across species. These findings were then used to evaluate if and how corticosteroid treatment could influence disease outcome in canine acute/acute-on-chronic pancreatitis. A scoping review was performed by searching the Agricola, CAB Abstracts, MEDLINE and Embase databases to identify relevant articles published before June 24, 2021. The inclusion criteria were English language, original research published in a peer-reviewed journal, and investigation of corticosteroid treatment effects on acute/acute-on-chronic pancreatitis by the outcome parameters clinical score, circulating CRP level, hospitalisation duration, mortality and pancreas histopathology. Research on any species was considered. Studies were rated based on the level of evidence, and methodological quality was evaluated based on similarity between groups at baseline, risk of bias and study group size. The reporting method was based on the PRISMA extension for scoping reviews. One thousand nine hundred fifty-four studies were identified, and 31 met the inclusion criteria. Five were canine studies, with 4 investigating experimentally induced pancreatitis; 5 were human clinical studies; and 21 were rodent studies of experimentally induced pancreatitis. The level of evidence ranged between randomised controlled trials and case series, the estimated risk of bias ranged from low to high, and the sample sizes ranged from very small to moderate. Evidence indicates that adding corticosteroid to symptomatic treatment of acute/acute-on-chronic canine pancreatitis could have a positive influence on disease outcome. However, the analysed evidence was based on several species, including both naturally occurring and experimentally induced pancreatitis; thus, the authors suggest that large randomised controlled studies should be performed in dogs with spontaneously occurring acute/acute-on-chronic pancreatitis to further elucidate a potential benefit of corticosteroid treatment.

Waterhouse-Friderichsen syndrome in a cat with Klebsiella spp. infection

OBJECTIVE

To describe a case of Waterhouse-Friderichsen syndrome of adrenocortical failure in a cat with Klebsiella spp. infection.

CASE SUMMARY

A 12-year-old male neutered domestic short-haired cat was referred for respiratory failure requiring mechanical ventilation. The cat remained comatose despite successful weaning from the ventilator and developed a Klebsiella pneumoniae pneumonia. On day 4 of hospitalization, the cat acutely deteriorated with profound hypotension, azotemia, and hyperkalemia, which rapidly progressed to cardiac arrest. Necropsy findings revealed massive adrenal hemorrhage and intralesional bacteria, termed Waterhouse-Friderichsen syndrome. Waterhouse-Friderichsen syndrome was suspected to have been the cause of acquired adrenocortical insufficiency and sudden death of the cat.

NEW OR UNIQUE INFORMATION

To the authors' knowledge, this is the first report of sepsis causing Waterhouse-Friderichsen syndrome in a veterinary species.

Critical illness-related corticosteroid insufficiency in dogs with systemic inflammatory response syndrome: A pilot study in 21 dogs

Critical illness-related corticosteroid insufficiency (CIRCI) refers to a lack of adequate corticosteroid activity, which occurs in up to 48% of dogs with sepsis. However, data regarding the occurrence of CIRCI in critically-ill dogs are still scarce. This study aimed to assess: (1) the relationship between CIRCI and clinicopathological inflammatory markers, hypotension and mortality; and (2) the impact of low-dose hydrocortisone treatment on survival. Twenty-one dogs diagnosed with systemic inflammatory response syndrome (SIRS) were enrolled in a prospective case-control study. All dogs were initially evaluated for adrenal function with an ACTH stimulation test and dogs with Δcortisol ≤ 3 μg/dL were diagnosed with CIRCI. Mean arterial pressure (MAP), white blood cell (WBC), band neutrophils (bNs), c-reactive protein (CRP), and 28-day mortality rate were assessed. Fourteen dogs were treated with low-dose hydrocortisone. The relationships between CIRCI and MAP, WBC, bN, CRP, basal cortisol and mortality were investigated, as was the association between mortality and hydrocortisone treatment. Ten of 21 (48%) dogs were diagnosed with CIRCI. Increased bNs were associated with the presence of CIRCI (P = 0.0075). CRP was higher in dogs with CIRCI (P = 0.02). Fourteen of 21 (66%) dogs died during the study (6/14 had CIRCI). Basal hypercortisolemia (>5 μg/dL) was associated with increased risk of mortality (P = 0.025). Based on our diagnostic criteria, CIRCI occurs frequently in dogs with SIRS and was associated with increased bNs and increased CRP. In this study, CIRCI and low-dose hydrocortisone treatment were not significantly associated with mortality, but basal hypercortisolemia was associated with increased mortality.

Retrospective evaluation of the use of hydrocortisone for treatment of suspected critical illness-related corticosteroid insufficiency (CIRCI) in dogs with septic shock (2010-2017): 47 cases

OBJECTIVE

To evaluate characteristics of septic shock patients treated with hydrocortisone (HC) due to suspicion of critical illness-related corticosteroid insufficiency (CIRCI) as compared to septic shock patients without suspicion of CIRCI.

DESIGN

Retrospective study between February 2010 and October 2017.

SETTING

University teaching hospital ICU.

ANIMALS

Data were collected for 47 dogs with septic shock. Twenty-one dogs were treated with HC (HC-treated) due to suspicion of CIRCI. Twenty-six dogs did not receive HC (non-HC-treated).

INTERVENTIONS

HC was administered either as an intermittent IV bolus or as a constant rate infusion (CRI) to those patients with suspected CIRCI.

MEASUREMENTS AND MAIN RESULTS

Significantly higher baseline APPLE_full scores and predicted mortality were detected in the HC-treated patients compared to non-HC-treated patients (0.87 vs 0.44 for predicted mortality, P = 0.039). Patients in the HC-treated group were on more vasopressors and cardiotonics than those in the non-HC-treated group (2.5 vs 1.5, P <0 .001). All patients initially responded to vasopressor administration, with average time to resolution of hypotension being 90 minutes for the HC-treated group compared to 60 minutes for the non-HC-treated group (P = 0.640). However, HC-treated patients took significantly longer to have a sustained resolution (a systolic blood pressure > 90 mm Hg or a mean blood pressure > 65 mm Hg for at least 4 h) of their hypotension after starting vasopressors, as compared to their non-HC-treated counterparts (8.5 vs 4 h, P = 0.001). Three (14.3%) HC-treated patients survived to discharge compared to 9 (34.6%) non-HC-treated patients, but this was not statistically significant.

CONCLUSIONS

HC-treated patients had a higher baseline risk of mortality than non-HC-treated patients. There was no significant difference in survival between the HC-treated and non-HC-treated septic shock patients. Further studies are needed to evaluate the use of HC in patients with suspected CIRCI.

A randomized cross-over trial assessing salivary and urinary cortisol concentrations after alfaxalone and propofol administration in healthy cats

The aim of this study was to assess the effects of commonly used anaesthetics alfaxalone and propofol on salivary and urinary cortisol in healthy cats. Fifteen male castrated research-purposed cats received randomly intravenous continuous rate infusions of 8 mg/kg/h of alfaxalone, 12 mg/kg/h of propofol and 2 ml/kg/h of Lactated Ringer's solution for 30 min, with intervals of 6 days between treatments. Saliva samples were collected for 24 h before each infusion and for 24 h from the start of each infusion. Urine was collected as single pooled samples over each 24 h period. Mean integrated saliva cortisol responses in cats treated with alfaxalone were greater than responses of cats treated with propofol (P = 0.034) and controls (P = 0.017). Integrated responses in cats treated with propofol did not differ from controls. The mean urinary cortisol/creatinine ratio (UCCR) was higher on the day of treatment than the day before treatment in cats treated with alfaxalone (P < 0.0001) and in cats treated with propofol (P = 0.0168) and did not differ between days in cats treated with lactated Ringer's solution. The mean UCCR was higher in cats treated with alfaxalone than in cats treated with lactated Ringer's solution (P = 0.0020) on the day of treatment. Mean total urinary cortisol over 24 h was greater in cats treated with alfaxalone than controls (P = 0.0267). In conclusion, alfaxalone increased short-term salivary and urinary cortisol concentrations in healthy cats as compared to propofol and a control group of non-anesthetised cats.

Clinical features and outcome of septic shock in dogs: 37 Cases (2008-2015)

OBJECTIVES

To describe patient characteristics of dogs with septic shock, investigate markers of disease severity, and assess treatment impact on outcome.

DESIGN

Retrospective study.

SETTING

Single center, university veterinary teaching intensive care unit.

ANIMALS

Thirty-seven dogs with septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Mean number of organ dysfunction was 3.24 ± 1.0, and included cardiovascular (100%), respiratory (73%), hematologic (68%), renal (49%), and hepatic (32%) dysfunction. The gastrointestinal tract was the most common source of sepsis. Mean blood pressure prior to resuscitation was 50 ± 8 mm Hg. All dogs were given IV fluids before vasopressor therapy with a mean rate of 12.1 ± 11.0 mL/kg/h. All dogs were given antimicrobials, administered within a mean of 4.3 ± 5.7 hours after diagnosis. Dopamine or norepinephrine was administered IV, respectively in 51.3% and 37.8% of dogs, with a mean duration of hypotension of 2.6 ± 3.0 hours. Mortality rate was 81.1%. Survivors were more likely to have a feeding tube (P = 0.007) and to have gastrointestinal sepsis (P = 0.012), and less likely to have respiratory dysfunction (P < 0.001). APPLE_Full scores (P = 0.014) and time to antimicrobial therapy (P = 0.047) were identified as predictors of mortality. Treatment bundles consisting of 7 interventions that may improve outcomes in people with septic shock were evaluated. Survivors received 4.1 ± 1.3 interventions, whereas nonsurvivors received 2.4 ± 1.4 (P = 0.003).

CONCLUSIONS

Septic shock in dogs confers a guarded prognosis. Early antimicrobial therapy and the utilization of treatment bundles may increase survivability in dogs with septic shock. More research is warranted to investigate the impact of specific interventions on survival.

Delayed type III hypersensitivity reaction with acute kidney injury in two dogs following administration of concentrated human albumin during treatment for hypoalbuminemia secondary to septic peritonitis

OBJECTIVE

To describe 2 dogs with acute kidney injury secondary to type III hypersensitivity reaction to 25% human serum albumin (HSA).

CASE SERIES SUMMARY

Two dogs were presented with evidence of septic peritonitis. The dogs were hospitalized following definitive surgical correction of a jejunal laceration following routine ovariohysterectomy, and removal of a jejunal foreign body. In the postoperative period, both dogs developed hypoalbuminemia and received 25% HSA. At the time of initial discharge, both dogs were doing well clinically and had normal renal parameters. Eleven and 18 days after HSA infusion, respectively, both dogs were re-presented with clinical signs of inappetence, vomiting, and lameness that progressed to urticaria, peripheral and angioedema, and petechiae, consistent with a delayed type III hypersensitivity reaction. Treatment for the type III hypersensitivity reaction to HSA included administration of diphenhydramine and glucocorticoids. Despite partial resolution of edema and joint swelling, both dogs developed progressive azotemia together with hypoalbuminemia and proteinuria. One dog developed an anuric acute kidney injury (AKI). Both dogs were humanely euthanized. Histopathology of the kidneys of both dogs was consistent with immune complex deposition and vasculitis.

NEW OR UNIQUE INFORMATION

Severe type III hypersensitivity reactions have been documented in healthy dogs and clinical patients following the administration of HSA. This report describes the first documented delayed type III hypersensitivity reaction in 2 dogs with septic peritonitis that resulted in AKI, glomerulonephritis, and oligo- to anuria in clinical patients following administration of 25% HSA.

Glucocorticoid metabolism in critically ill dogs (Canis lupus familiaris)

Critical illness due to sepsis is a major global health concern associated with a high burden of mortality and cost. Glucocorticoid dysregulation in human sepsis is associated with poorer outcomes. This study examines glucocorticoid metabolism in septic canine patients to delineate elements of cellular dysregulation in common with critically ill humans and explore potential differences. This was a prospective case-control study conducted in the veterinary specialist critical care departments of two University teaching hospitals. Critically ill canine patients with naturally occurring sepsis or septic shock were compared with an in-hospital control population. Serum total, bound, and free cortisol concentrations were increased in septic shock (P < 0.001), and higher bound cortisol was associated with nonsurvival (P = 0.026). Urinary Gas Chromatography-Tandem Mass Spectrometry was performed to assess urinary glucocorticoid metabolites and estimate intracellular glucocorticoid metabolism. Decreased renal 11β-hydroxysteroid dehydrogenase 2 (11βHSD2) activity inferred from increased urinary cortisol-to-cortisone ratio was observed in critically ill dogs (P < 0.001). Decreased 11βHSD2 activity (P = 0.019) and increased A-ring reduction of cortisone (P = 0.001) were associated with nonsurvival within the critically ill dogs. Intriguingly, two dogs were identified with low circulating total cortisol (<2 mg/dL) associated with increased A-ring reduction of cortisol, not previously described. Investigation of spontaneous canine sepsis and septic shock reveals dysregulation of cortisol to cortisone conversion similar to that observed in human patients, but with differences in A-ring reduction compared with those reported in humans. In addition, two dogs with high levels of cortisol inactivation associated with low circulating cortisol concentrations were identified.

Thyroid axis and adrenal activity in 28 day survivor and nonsurvivor dogs involved in recent road traffic accidents: A cohort study of 420 dogs

The objective of this retrospective cohort study was to determine the impact of a recent trauma on thyroid axis and adrenal activity in dogs and to assess the usefulness of urinary cortisol-to-creatinine ratio (UCCR), basal serum thyroid-stimulating hormone (TSH), total thyroxine (tT4), and free thyroxine (fT4) concentrations in predicting outcome in dogs traumatized by a road traffic accident (RTA). An RTA exposed group of 210 dogs was evaluated within 24  hours of the trauma. Their data were compared with data from a matched group of dogs with other diagnoses. UCCR was positively correlated with the trauma severity and was higher in the exposed group than in the nonexposed group (median 101.500 vs. 21.02; p < 0.0001). tT4 values were statistically similar between the two groups, but were correlated with a trauma score, while TSH (median = 0.050 vs. 0.080 ng/mL; p < 0.0001) and fT4 (median = 15.850 vs. 17.950 pmol/L; p = 0.0037) were significantly lower for the exposed group. Nonsurvivors in comparison to survivors presented and higher median UCCR (181.800 vs. 93.850 respectively; p = 0.020), and a lower serum fT4 (12.700 vs. 16.500 pmol/L, respectively; p = 0.0046). A similar pattern had been observed for tT4. TSH levels were not predictive of survival. This study provides insights into the endocrine characteristics of dogs suffering from acute trauma. UCCR was higher while fT4 and TSH were both lower in RTA-injured dogs than in dogs affected by other conditions. Furthermore low fT4 and tT4, and a high UCCR could be useful prognostic factors in dogs affected by RTA trauma.

Effect of clinical signs, endocrinopathies, timing of surgery, hyperlipidemia, and hyperbilirubinemia on outcome in dogs with gallbladder mucocele

Gallbladder mucocele (GBM) is a common extra-hepatic biliary syndrome in dogs with death rates ranging from 7 to 45%. Therefore, the aim of this study was to identify the association of survival with variables that could be utilized to improve clinical decisions. A total of 1194 dogs with a gross and histopathological diagnosis of GBM were included from 41 veterinary referral hospitals in this retrospective study. Dogs with GBM that demonstrated abnormal clinical signs had significantly greater odds of death than subclinical dogs in a univariable analysis (OR, 4.2; 95% CI, 2.14-8.23; P<0.001). The multivariable model indicated that categorical variables including owner recognition of jaundice (OR, 2.12; 95% CI, 1.19-3.77; P=0.011), concurrent hyperadrenocorticism (OR 1.94; 95% CI, 1.08-3.47; P=0.026), and Pomeranian breed (OR, 2.46; 95% CI 1.10-5.50; P=0.029) were associated with increased odds of death, and vomiting was associated with decreased odds of death (OR, 0.48; 95% CI, 0.30-0.72; P=0.001). Continuous variables in the multivariable model, total serum/plasma bilirubin concentration (OR, 1.03; 95% CI, 1.01-1.04; P<0.001) and age (OR, 1.17; 95% CI, 1.08-1.26; P<0.001), were associated with increased odds of death. The clinical utility of total serum/plasma bilirubin concentration as a biomarker to predict death was poor with a sensitivity of 0.61 (95% CI, 0.54-0.69) and a specificity of 0.63 (95% CI, 0.59-0.66). This study identified several prognostic variables in dogs with GBM including total serum/plasma bilirubin concentration, age, clinical signs, concurrent hyperadrenocorticism, and the Pomeranian breed. The presence of hypothyroidism or diabetes mellitus did not impact outcome in this study.

The interpretive contribution of the baseline serum cortisol concentration of the ACTH stimulation test in the diagnosis of pituitary dependent hyperadrenocorticism in dogs

Background

Current recommendation for performing the ACTH stimulation test (ACTHST) for diagnosis of hyperadrenocorticism (HAC) advocates the collection of baseline serum cortisol concentration (BC), but no references for interpretation of its results exist.

Objective

Evaluate the contribution of BC of the ACTHST to the diagnosis of HAC.

Animals

Fifty‐four dogs were evaluated for suspected HAC at a referral hospital.

Methods

Records of dogs that had been evaluated by ACTHST for suspected HAC were reviewed. Receiver operator characteristics (ROC) analyses were used to assess the performance of BC, post‐stimulation serum cortisol concentrations (PC), post‐to‐baseline cortisol concentration difference (DeltaC) and quotient (RatioC) for the diagnosis of HAC by comparing the area under the ROC curve (AUC) of PC to each of the other tests.

Results

The AUC of PC (95% confidence interval [CI]: 0.92; 95% CI, 0.81‐0.98) was significantly higher than AUCs of BC (0.70; 95% CI, 0.56‐0.82; P = .01) and RatioC (0.55; 95% CI, 0.41‐0.69; P < .001), and was not significantly different from AUC of DeltaC (0.86; 95% CI, 0.74‐0.94; P = .09). An optimal cutoff value of 683 nmol/L (24.8 μg/dL) for PC yielded a sensitivity of 86% and a specificity of 94%, respectively, and a cutoff value of 718 nmol/L (26.0 μg/dL) yielded a specificity of 100% with of 81% sensitivity for the diagnosis of pituitary‐dependent HAC.

Conclusion and Clinical Importance

The PC had good discriminatory ability for the diagnosis of HAC. It was comparable to DeltaC, whereas BC and RatioC were ineffective. Current recommendations to collect samples for BC appear redundant.

Hydrocortisone therapy in a cat with vasopressor-refractory septic shock and suspected critical illness-related corticosteroid insufficiency

A 27‐month‐old female cat was presented with septic peritonitis secondary to a ruptured pyometra and subsequent pyothorax. Vasopressor‐refractory septic shock led to a suspicion of critical illness‐related corticosteroid insufficiency, successfully treated with intravenous hydrocortisone. Previous megestrol acetate administration may have played a role in the development of adrenocortical dysfunction.

Adrenal function in cats with cholestatic liver disease

Cats with cholestatic liver disease experience significant morbidity and mortality when they undergo invasive procedures under anesthesia. Although inadequate adrenal response might account for these outcomes, adrenal function in cats with cholestatic liver disease has not been documented, to our knowledge. The goal of our study was to describe adrenal function in these cats. Twenty-seven cats with a serum bilirubin >230 µmol/L (3 mg/dL) and serum alanine aminotransferase >2 times the upper limit of normal had pre– and 60-min post–adrenocorticotropic hormone (ACTH) cortisol analysis after administration of 5 µg/kg cosyntropin intravenously. The change in cortisol concentrations (delta cortisol) was calculated. Pre- and post-ACTH cortisol concentrations were compared to reference values. Pre-ACTH, post-ACTH, and delta cortisol values were compared between cats surviving to discharge or for 30 d postdischarge. Mean pre-ACTH cortisol levels (205 ± 113 nmol/L [7.4 ± 4.2 µg/dL]) and post-ACTH cortisol levels (440 ± 113 nmol/L [15.9 ± 4.1 g/dL]) in cholestatic cats were significantly greater than reference values in clinically normal cats. There was no association of pre- or post-ACTH cortisol with survival. Cats with a delta cortisol <179 nmol/L (6.5 µg/dL) were more likely to be non-survivors at 30 d post-discharge ( p = 0.037) than cats with delta cortisol >179 nmol/L (6.5 µg/dL). Results indicate that cats with cholestasis have high basal and ACTH-stimulated cortisol values. A delta cortisol <179 nmol/L (6.5 µg/dL) defines a population of cats that have decreased 30-d survival.

Controversies surrounding critical illness-related corticosteroid insufficiency in animals

OBJECTIVES

To describe the controversies surrounding critical illness-related corticosteroid insufficiency (CIRCI) and the use of hydrocortisone in critically ill patients, and to present published diagnostic and therapeutic strategies in companion veterinary species.

ETIOLOGY

Critical illness-related corticosteroid insufficiency may be due to hypothalamic-pituitary-adrenal (HPA) axis dysfunction, alterations in cortisol-plasma protein binding, target cell enzymatic changes, changes in glucocorticoid receptor (GR) function, or a combination of these or other factors present during critical illness.

DIAGNOSIS

Appropriate tests to diagnose CIRCI are unknown. The diagnosis in people is currently based on response to treatment with hydrocortisone. There is currently no consensus on appropriate diagnostic feature(s) in veterinary species.

THERAPY

Low-dose hydrocortisone is the treatment of choice for patients with CIRCI.

PROGNOSIS

If the patient survives the critical illness, prognosis for resolution of CIRCI and hydrocortisone dependence is very good.

Use of the cortisol-to-ACTH ratio for diagnosis of primary hypoadrenocorticism in dogs

Background

The ACTH stimulation test is currently required for definitive diagnosis of hypoadrenocorticism. Increased cost of synthetic ACTH (cosyntropin) has prompted a search for alternative diagnostic methods.

Objective

The purpose of this study was to determine whether a cortisol‐to‐ACTH ratio (CAR) can be used to differentiate dogs with hypoadrenocorticism from normal dogs and those with nonadrenal illness.

Animals

Eight healthy dogs (H), 19 dogs with nonadrenal illness (NAI), and 15 dogs with hypoadrenocorticism (HAD).

Methods

Dogs in the HAD group were retrospectively identified from PUVTH medical records. The NAI group consisted of hospitalized dogs with clinical signs, clinicopathologic findings, or both, consistent with a diagnosis of hypoadrenocorticism, but in which hypoadrenocorticism was ruled out based on ACTH stimulation test results. Healthy dogs were recruited from hospital staff and students. Endogenous ACTH concentrations and cortisol concentrations before and after ACTH stimulation were measured in all dogs.

Results

Baseline cortisol concentration was significantly lower, and ACTH concentration was significantly higher, in the HAD group versus the H and NAI group (P < .001). However, there was overlap among groups. Cortisol‐to‐ACTH ratio was significantly lower in the HAD group versus the H and NAI groups (P < .001), and there was no overlap between the HAD group and the other 2 groups.

Conclusions and Clinical Importance

CAR can be used for definitive diagnosis of primary hypoadrenocorticism.

Multiple organ dysfunction syndrome in humans and animals

Multiple organ dysfunction syndrome (MODS), defined as the presence of altered organ function in an acutely ill patient such that homeostasis cannot be maintained without intervention, is a cause of high morbidity and mortality in humans and animals. Many advances have been made in understanding the pathophysiology and treatment of this syndrome in human medicine, but much still is unknown. This comparative review will provide information regarding the history and pathophysiology of MODS in humans and discuss how MODS affects each major organ system in animals.

Validation of a low-dose ACTH stimulation test in healthy adult horses

OBJECTIVE

To determine the lowest ACTH dose that would induce a maximum increase in serum cortisol concentration in healthy adult horses and identify the time to peak cortisol concentration.

DESIGN

Evaluation study.

ANIMALS

8 healthy adult horses.

PROCEDURES

Saline (0.9% NaCl) solution or 1 of 4 doses (0.02, 0.1, 0.25, and 0.5 μg/kg [0.009, 0.045, 0.114, and 0.227 μg/lb]) of cosyntropin (synthetic ACTH) were administered IV (5 treatments/horse). Serum cortisol concentrations were measured before and 30, 60, 90, 120, 180, and 240 minutes after injection of cosyntropin or saline solution; CBCs were performed before and 30, 60, 120, and 240 minutes after injection.

RESULTS

For all 4 doses, serum cortisol concentration was significantly increased, compared with the baseline value, by 30 minutes after administration of cosyntropin; no significant differences were detected among maximum serum cortisol concentrations obtained in response to administration of doses of 0.1, 0.25, and 0.5 μg/kg. Serum cortisol concentration peaked 30 minutes after administration of cosyntropin at a dose of 0.02 or 0.1 μg/kg, with peak concentrations 1.5 and 1.9 times, respectively, the baseline concentration. Serum cortisol concentration peaked 90 minutes after administration of cosyntropin at a dose of 0.25 or 0.5 μg/kg, with peak concentrations 2.0 and 2.3 times, respectively, the baseline concentration. Cosyntropin administration significantly affected WBC, neutrophil, and eosinophil counts and the neutrophil-to-lymphocyte ratio.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that in healthy horses, administration of cosyntropin at a dose of 0.1 μg/kg resulted in maximum adrenal stimulation, with peak cortisol concentration 30 minutes after cosyntropin administration.

Plasma nitrate/nitrite concentrations in dogs with naturally developing sepsis and non-infectious forms of the systemic inflammatory response syndrome

The aim of this prospective observational study was to evaluate the differences in plasma nitrate/nitrite concentrations between dogs with sepsis and those with non-infectious forms of the systemic inflammatory response syndrome (SIRS). Eighteen dogs with sepsis, 20 dogs with SIRS and 29 healthy control dogs were enrolled. Blood samples were obtained from the dogs within 12 hours of admission to the University of Missouri Veterinary Medical Teaching Hospital (MU VMTH) Intensive Care Unit (ICU) in lithium heparin blood tubes. Plasma nitrate/nitrite concentrations were measured using the Greiss reaction. Plasma nitrate/nitrite concentrations at presentation, clinical parameters, organ dysfunction and in-hospital mortality were compared between groups. Plasma total nitrate/nitrite was significantly greater in the sepsis group compared with the control group (P=0.005) and SIRS group (P=0.037). There was no statistical difference in plasma nitrate/nitrite concentration between the SIRS and control groups (P=0.489). The sensitivity was 66.7 per cent (95 per cent CI, 41 to 87 per cent) and the specificity was 75.5 per cent (95 per cent CI, 61 to 87 per cent) for differentiating dogs with sepsis from dogs without sepsis.

Critical illness-related corticosteroid insufficiency in a dog with septic shock

OBJECTIVE

To describe a case of hydrocortisone-responsive hypotension and critical illness-related corticosteroid insufficiency (CIRCI) in a dog with septic shock.

CASE SUMMARY

A dog with aspiration pneumonia developed septic shock with pressor-refractory hypotension. A standard ACTH stimulation test was performed that showed a blunted cortisol response consistent with CIRCI. Reversal of shock was achieved within 2 hours of hydrocortisone administration, and complete weaning from pressors was accomplished over the subsequent 8 hours. The patient recovered and was discharged from the hospital. An ACTH stimulation test performed 1 month after hospital discharge showed normal adrenal responsiveness consistent with resolution of CIRCI.

NEW OR UNIQUE INFORMATION PROVIDED

This case is the first published report of hydrocortisone-responsive hypotension and transient CIRCI associated with naturally occurring septic shock in a dog.

Infection, immunity and the neuroendocrine response

The Central Nervous (CNS) and Immune Systems (IS) are the two major adaptive systems which respond rapidly to numerous challenges that are able to compromise health. The defensive response strictly linking innate to acquired immunity, works continuously to limit pathogen invasion and damage. The efficiency of the innate response is crucial for survival and for an optimum priming of acquired immunity. During infection, the immune response is modulated by an integrated neuro-immune network which potentiates innate immunity, controls potential harmful effects and also addresses metabolic and nutritional modifications supporting immune function. In the last decade much knowledge has been gained on the molecular signals that orchestrate this integrated adaptive response, with focus on the systemic mediators which have a crucial role in driving and controlling an efficient protective response. These mediators are also able to signal alterations and control pathway dysfunctions which may be involved in the persistence and/or overexpression of inflammation that may lead to tissue damage and to a negative metabolic impact, causing retarded growth. This review aims to describe some important signalling pathways which drive bidirectional communication between the Immune and Nervous Systems during infection. Particular emphasis is placed on pro-inflammatory cytokines, immunomodulator hormones such as Glucocorticoids (GCs), Growth hormone (GH), Insulin-like Growth Factor-1 (IGF-1), and Leptin, as well as nutritional factors such as Zinc (Zn). Finally, the review includes up-to-date information on this neuroimmune cross-talk in domestic animals. Data in domestic animal species are still limited, but there are several exciting areas of research, like the potential interaction pathways between mediators (i.e. cytokine-HPA regulation, IL-6-GCS-Zn, cytokines-GH/IGF-1, IL-6-GH-Leptin and thymus activity) that are or could be promising topics of future research in veterinary medicine.

Pituitary-adrenal function in dogs with acute critical illness

OBJECTIVE

To evaluate pituitary-adrenal function in critically ill dogs with sepsis, severe trauma, and gastric dilatation-volvulus (GDV).

DESIGN

Cohort study.

ANIMALS

31 ill dogs admitted to an intensive care unit (ICU) at Washington State University or the University of Pennsylvania; all dogs had acute critical illness for < 48 hours prior to admission.

PROCEDURES

Baseline and ACTH-stimulated serum cortisol concentrations and baseline plasma ACTH concentrations were assayed for each dog within 24 hours after admission to the ICU. The change in cortisol concentrations (Delta-cortisol) was calculated for each dog. Morbidity and mortality data were recorded for each patient.

RESULTS

Overall, 17 of 31 (55%) acutely critically ill dogs had at least 1 biochemical abnormality suggestive of adrenal gland or pituitary gland insufficiency. Only 1 (3%) dog had an exaggerated response to ACTH stimulation. Dogs with Delta-cortisol < or = 83 nmol/L were 5.7 times as likely to be receiving vasopressors as were dogs with Delta-cortisol > 83 nmol/L. No differences were detected among dogs with sepsis, severe trauma, or GDV with respect to mean baseline and ACTH-stimulated serum cortisol concentrations, Delta-cortisol, and baseline plasma ACTH concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

Biochemical abnormalities of the hypothalamic-pituitary-adrenal axis indicative of adrenal gland or pituitary gland insufficiency were common in critically ill dogs, whereas exaggerated responses to ACTH administration were uncommon. Acutely ill dogs with Delta-cortisol < or = 83 nmol/L may be more likely to require vasopressors as part of the treatment plan.