CORRELATIONS AMONG ULTRASONOGRAPHIC MEASUREMENTS OF OPTIC NERVE SHEATH DIAMETER,AGE, AND BODY WEIGHT IN CLINICALLY NORMAL HORSES

Early diagnosis of high intracranial pressure (ICP) is critical for minimizing progressive brain injury due to reduced cerebral perfusion. In people, detecting enlargement of the optic nerve sheath diameter (ONSD) by transpalpebral ultrasonography has been found to be an accurate test for high ICP. Aims of this prospective, observational, cross‐sectional study were to test hypotheses that (1) ultrasonographic measurement of ONSD would be repeatable in horses, (2) have acceptable interobserver agreement, and (3) would be correlated with age and body weight. The sample population included 48 horses without clinical signs of high ICP and with varying ages and body weights. Two observers independently performed ONSD measurements in both eyes. All measurements ranged from 2.6 to 6.5 mm. The mean difference of repeated measures within observers was ≤0.1 mm and the coefficients of variation ranged from 5.0% to 8.8%. The mean difference of measures between observers was ≤0.2 mm. After correcting for performing multiple tests, no significant rank correlation (all r < 0.4 [absolute value]) was detected between ONSD and age or body weight. However, we observed smaller ONSD in foals versus adults (all P ≤ 0.002). In the foals, all observed measures of rostrocaudal and dorsoventral ONSD were <5 mm. In the adults, all observed measures of rostrocaudal and dorsoventral ONSD were ≤6.5 mm. Findings indicated that ultrasonographic ONSD measurement is a feasible test for use in horses of varying ages and sizes. Further investigation of this ultrasonographic measure as a clinical test for horse with suspected high ICP is warranted.     

Glutathione Peroxidase Activity,Plasma Total Antioxidant Capacity,and Urinary F2‐ Isoprostanes as Markers of Oxidative Stress in Anemic Dogs

Background

Oxidative stress plays a role in the pathophysiology of several diseases and has been documented as a contributor to disease in both the human and veterinary literature. One at‐risk cell is the erythrocyte, however, the role of oxidative stress in anemia in dogs has not been widely investigated.

Hypothesis/Objective

Anemic dogs will have an alteration in the activity of glutathione peroxidase (GPx), a decrease in of total antioxidant capacity (TAC), and an increased concentration of urinary 15‐F₂‐isoprostanes (F₂‐IsoP) when compared to healthy dogs.

Animals

40 client‐owned dogs with anemia (PCV <30%) age‐matched to 40 client‐owned healthy control dogs.

Methods

Prospective, cross‐sectional study. Whole blood GPx activity, plasma TAC, and urinary F₂‐isoprostane concentrations were evaluated in each dog and compared between groups.

Results

Anemic dogs had significantly lower GPx activity (43.1 × 10³ +/‐ 1.6 × 10³ U/L) than did dogs in the control group (75.8 × 10³ +/‐ 2.0 × 10³ U/L; P < 0.0001). The GPx activity in dogs with hemolysis (10³ +/‐ 0.8 × 10³ U/L) was not significantly different (P = 0.57) than in dogs with nonhemolytic anemia (43.5 × 10³ +/‐ 1.1 × 10³ U/L). The TAC concentrations (P = 0.15) and urinary F₂‐isoprostanes (P = 0.73) did not significantly differ between groups.

Conclusions and Clinical Importance

Glutathione peroxidase activity was significantly decreased in anemic dogs indicating oxidative stress. Additional studies are warranted to determine if antioxidant supplementation would improve survival and overall outcome as part of a therapeutic regimen for anemic dogs.     

c‐Kit Mutation and Localization Status as Response Predictors in Mast Cell Tumors in Dogs Treated with Prednisone and Toceranib or Vinblastine

Background

KIT inhibitors, such as toceranib (TOC), and vinblastine (VBL) have not been prospectively compared in the treatment of macroscopic mast cell tumors (MCTs). Also, it is unknown whether VBL or TOC is superior for treating MCT without c‐kit mutations.

Hypothesis/Objectives

To determine the value of KIT genotyping and localization in treatment decisions for dogs with macroscopic MCT. We hypothesized that c‐kit mutated MCT would have a better response to TOC than VBL.

Animals

Eighty‐eight client‐owned dogs with macroscopic MCT.

Methods

Prospective, randomized trial. Dogs were randomized to TOC (2.75 mg/kg EOD) or VBL (2.5 mg/m² weekly × 4 then EOW) by KIT localization and c‐kit mutation status using an adaptive randomization scheme.

Results

Sixty dogs were allocated to TOC and 28 to VBL. Of the dogs receiving TOC, 20% had c‐kit mutations, compared to 30% receiving VBL (P = 0.74). Overall response rates were 46% (TOC) and 30% (VBL) (odds ratio = 1.56 [0.62–3.92]; P = 0.28). Median progression‐free survival (PFS) for dogs receiving VBL was 78 days (7–1,521) and for TOC 95.5 (14–990); hazard ratio (HR) = 1.34 [0.72–2.50]; P = 0.36. Median overall survival (OS) was 241.5 days (10–1,521) for the VBL group and 159 (20–990) for the TOC group; HR = 0.80 ([0.45–1.41]; P = 0.44).

Conclusions and Clinical Importance

Neither PFS nor OS was significantly different between treatment groups. As the proportion of dogs with c‐kit mutations was not different between treatment groups in this population of dogs, c‐kit mutation status did not predict treatment response.     

Comparison of calculated lumbosacral epidural volumes of injectate using a dose regimen based on body weight versus length of the vertebral column in dogs

Objective

To compare volumes for epidural injection calculated on body weight or the length from sacrococcygeal space to occipital crest in dogs.

T2‐WEIGHTED MAGNETIC RESONANCE IMAGING MEASUREMENTS OF OPTIC NERVE SHEATH DIAMETER IN DOGS WITH AND WITHOUT PRESUMED INTRACRANIAL HYPERTENSION

Intracranial hypertension is a cause of cerebral ischemia and neurologic deficits in dogs. Goals of this retrospective study were to test interobserver agreement for MRI measurements of optic nerve sheath diameter and associations between optic nerve sheath diameter, signalment data, and presumed intracranial hypertension status in a cohort of dogs. A veterinary radiologist interpreted scans of 100 dogs and dogs were assigned to groups based on presence or absence of at least two MRI characteristics of presumed intracranial hypertension. Two observers who were unaware of group status independently measured optic nerve diameter from transverse T2‐weighted sequences. Mean optic nerve sheath diameter for all dogs was 3 mm (1–4 mm). The mean difference between observers was 0.3 mm (limits of agreement, ?0.4 and 1.0 mm). There was no correlation between optic nerve sheath diameter and age for either observer (r = ?0.06 to 0.00) but a moderate positive correlation was observed between optic nerve sheath diameter and body weight for both observers (r = 0.70–0.76). The 22 dogs with presumed intracranial hypertension weighed less than the 78 dogs without (P = 0.02) and were more often female (P = 0.04). Dogs with presumed intracranial hypertension had a larger ratio of optic nerve sheath diameter to body weight for each observer‐side pair (P = 0.01–0.04) than dogs without. Findings indicated that the ratio of MRI optic nerve sheath diameter relative to body weight may be a repeatable predictor of intracranial hypertension in dogs.     

Spectrophotometry and Ultracentrifugation for Measurement of Plasma Lipids in Dogs with Diabetes Mellitus

Background

There are conflicting reports of plasma lipoprotein lipid content in dogs with diabetes mellitus (DM).

Objectives

To determine lipoprotein lipid content of plasma of dogs with DM by spectrophotometry and ultracentrifugation; to compare lipoprotein lipid content in diabetic and healthy dogs; and to quantify apolipoprotein B‐100 (ApoB) in dogs with DM.

Animals

22 dogs with DM and 9 healthy dogs.

Methods

Cross‐sectional study. Triglyceride (TG), total cholesterol (TC), and high‐density lipoprotein cholesterol (HDL‐C) concentrations were measured by spectrophotometry. Very low‐density lipoprotein cholesterol (VLDL‐C) and low‐density lipoprotein cholesterol (LDL‐C) concentrations were calculated after ultracentrifugation. Non‐HDL‐C cholesterol was calculated by subtracting HDL‐C from TC. ApoB was quantified by ELISA. The Mann‐Whitney test was used for comparison of median lipoprotein concentrations, and Spearman's correlation was used to assess associations between ApoB and lipoprotein fractions.

Results

All values are reported in mg/dL. Median TG (122), TC (343.5), HDL‐C, (200), VLDL‐C, (27) LDL‐C (68), non‐HDL‐C (114), and ApoB (320) were significantly higher in dogs with DM, compared to healthy dogs (57, 197, 168, 12, 16, 31, and 258, respectively, P‐values 0.0079, <0.001, 0.029, 0.011, <0.001, <0.001, 0.025, respectively). A significant association was found between ApoB and LDL‐C (Spearman's rho = 0.41, P = 0.022) and between ApoB and non‐HDL‐C (Spearman's rho = 0.40, P = 0.027).

Conclusions and Clinical Importance

Dyslipidemia of dogs with DM is characterized by pronounced increases in LDL‐C and non‐HDL‐C concentrations, although all lipoprotein fractions are significantly increased. Knowledge of specific lipoprotein fraction alterations in dogs with DM can enhance treatment options for diabetic dyslipidemia in dogs.     

Fluoroscopic Estimation of Thoracic Dimensional Changes in Healthy Dogs

Background

Current methods available for assessing alterations in lung mechanics require sophisticated equipment and are of limited availability. A method that could assess lung area change with respiration might be a clinically useful surrogate for assessing lung compliance.

Objective

To use fluoroscopy to determine percent change in thoracic and lung areas in healthy dogs.

Animals

Forty‐four client‐owned dogs with no evidence of respiratory disease.

Methods

Prospective study. Resting respiration was recorded fluoroscopically, and peak inspiratory and expiratory frames were captured for 3 typical respiratory cycles. The number of intrathoracic pixels in the entire thoracic cavity was measured for both inspiration and expiration, and the average percent change in intrathoracic area was determined for each dog. This process was repeated by a hemithorax measurement of lung area that excluded the mediastinum and cardiac silhouette. Proposed reference ranges (and 95% confidence intervals [CI]) were computed by a nonparametric percentile distribution.

Results

Median percent change in thoracic dimension for the total thorax measurement was 12.5% (CI, 8.9–24.0%). Median percent change for the hemithorax measurement was significantly (P < 0.001) larger (20.8%, CI, 14.3–37.6%). Both measurement techniques were correlated with body weight but not with age, sex, thoracic conformation, body condition score (BCS), or breed.

Conclusions and Clinical Importance

Fluoroscopy allows a noninvasive and repeatable measure of lung area changes during respiration that must be corrected for body weight. Additional studies in dogs with respiratory diseases are needed to determine its utility in detecting clinically useful alterations in lung area changes.     

Echocardiographic Estimates of Right Ventricular Systolic Function in Dogs with Myxomatous Mitral Valve Disease

Background

Right ventricular (RV) dysfunction independently predicts outcomes in human myxomatous mitral valve disease (MMVD). There is limited information regarding RV systolic function in dogs with MMVD.

Hypothesis

Right ventricular systolic function differs among stages of disease, decreasing in decompensated MMVD.

Animals

Thirty‐sixclient‐owned dogs with MMVD not receiving oral cardiovascular medications.

Methods

Prospective clinical study. Dogs were categorized according to disease severity as ACVIM Stage B1, B2, or C. Seven echocardiographic indices of RV systolic function were measured. Groups were compared by 1‐way ANOVA and Tukey's HSD test. Frequencies of cases with cardiac remodeling falling outside previously established reference intervals were compared using Fisher's exact test. Intra‐ and interobserver measurement variability was calculated for each RV function index.

Results

The indices TAPSE (P = 0.029), RV St_L (P = 0.012), and RV StR_L (P = 0.041) were significantly different between groups. A greater proportion of B2 dogs (7 of 12) had TAPSE values above reference intervals compared with B1 (2 of 12) or C (2 of 12) dogs (P = 0.027). Measurement variability of TAPSE, RV S', and RV St_G was clinically acceptable.

Conclusions and Clinical Importance

Right ventricular systolic function differs between stages of MMVD, increasing in stage B2, and declining in stage C. The prognostic importance of RV function indices, particularly TAPSE, might be worth evaluating in dogs with MMVD.     

Immune Function in Critically Ill Dogs

Background

People with critical illness (CI) commonly develop various forms of immune dysfunction, however, there is limited information concerning immune dysfunction in dogs with CI.

Hypothesis

The immune response in CI dogs differs from that of healthy dogs.

Animals

Immunologic variables were compared between 14 dogs with CI, defined as APPLE_fast score of >20 points, admitted to the University of Missouri Veterinary Health Center Small Animal Clinic Intensive Care Unit and healthy controls (n = 15).

Methods

Cohort study evaluating constitutive and lipopolysaccharide (LPS)‐stimulated TNF‐α, IL‐6, and IL‐10 production, phagocytosis of opsonized E. coli and respiratory burst capacity after opsonized E. coli or phorbol 12‐myristate 13‐acetate (PMA) stimulation, peripheral blood lymphocyte phenotype, and monocyte expressions of HLA‐DR and TLR‐4.

Results

Lipopolysaccharide‐stimulated leukocyte TNF‐α (median, Q1, Q3; CI, 49, 49, 120; control, 655, 446, 1174 pg/mL; P = < 0.001), IL‐6 (median, Q1, Q3; CI, 49, 49, 64; control, 100, 49, 166 pg/mL; P = 0.029), and IL‐10 (CI, 49, 49, 56; control, 96, 49, 203 pg/mL; P = 0.014) production and both E. coli (median, Q1, Q3; CI, 60.5, 43, 88.5; control, 86.6, 81, 89.2%; P = 0.047) and PMA (CI, 40, 11.7, 70; control, 93, 83, 97.6%; P = < 0.001)‐stimulated respiratory burst capacity significantly decreased in CI dogs. Percentage of monocytes expressing TLR‐4 greater in the CI dogs (median, Q1, Q3; CI, 46.9, 24.3, 64.2; control, 16.4, 9.4, 26.2%; P = 0.005).

Conclusion

These findings suggest dogs with CI develop immune system alterations that result in reduced respiratory burst function and cytokine production despite upregulation of TLR‐4.     

Effect of Weight Loss in Obese Dogs on Indicators of Renal Function or Disease

Background

Obesity is a common medical disorder in dogs, and can predispose to a number of diseases. Human obesity is a risk factor for the development and progression of chronic kidney disease.

Objectives

To investigate the possible association of weight loss on plasma and renal biomarkers of kidney health.

Animals

Thirty‐seven obese dogs that lost weight were included in the study.

Methods

Prospective observational study. Three novel biomarkers of renal functional impairment, disease, or both (homocysteine, cystatin C, and clusterin), in addition to traditional markers of chronic renal failure (serum urea and creatinine, urine specific gravity [USG], urine protein‐creatinine ratio [UPCR], and urine albumin corrected by creatinine [UAC]) before and after weight loss in dogs with naturally occurring obesity were investigated.

Results

Urea (P = .043) and USG (P = .012) were both greater after weight loss than before loss, whilst UPCR, UAC, and creatinine were less after weight loss (P = .032, P = .006, and P = .026, respectively). Homocysteine (P < .001), cystatin C (P < .001) and clusterin (P < .001) all decreased upon weight loss. Multiple linear regression analysis revealed associations between percentage weight loss (greater weight loss, more lean tissue loss; r = ?0.67, r² = 0.45, P < .001) and before‐loss plasma clusterin concentration (greater clusterin, more lean tissue loss; r = 0.48, r² = 0.23, P = .003).

Conclusion and Clinical Importance

These results suggest possible subclinical alterations in renal function in canine obesity, which improve with weight loss. Further work is required to determine the nature of these alterations and, most notably, the reason for the association between before loss plasma clusterin and subsequent lean tissue loss during weight management.

     

Risk Factors for Death in Dogs Treated for Esophageal Foreign Body Obstruction: A Retrospective Cohort Study of 222 Cases (1998–2017)

Background

Limited data exist describing risk factors for death, and long‐term outcomes in dogs with esophageal foreign body (EFB) obstruction.

Hypothesis/Objectives

To evaluate short‐ and long‐term outcomes, and analyze risk factors for death in dogs with EFB obstruction. We hypothesized duration of entrapment and treatment type would affect outcome.

Animals

A total of 222 dogs were treated for EFB obstruction at an emergency and referral hospital between March 1998 and March 2017.

Methods

Medical records for dogs with EFB were retrospectively evaluated.

Results

Foreign material most frequently was osseous (180/222 [81%]), with distal esophagus the most common location (110/222 [49.5%]). Duration of clinical signs was not associated with risk of death (OR = 1.08, 95% CI 0.99–1.17; P = 0.2). Entrapment was treated by endoscopy (204/222 [91.8%]), surgery after endoscopic attempt (13/222 [5.9%]), and repeat endoscopy after surgery was recommended but declined (5/222 [2.3%]). In‐hospital case fatality rate was 11/222 (5%). Risk of death was significantly higher with surgery (OR = 20.1, 95% CI 3.59–112.44; P = 0.001), and 5/5 (100%) of dogs died if undergoing endoscopy after surgery was recommended but declined. Increasing numbers of postprocedural complications (OR = 3.44, CI 2.01–5.91; P < 0.001), esophageal perforation (OR = 65.47, CI 4.27–1004.15; P = 0.003), and postprocedure esophageal hemorrhage (OR = 11.81, CI 1.19–116.77; P = 0.04) increased in‐hospital risk of death. Esophageal strictures were reported in 4/189 (2.1%) of survivors available for follow‐up.

Conclusions and Clinical Importance

Death is uncommon in canine EFB; however, treatment type affects outcome, and these data should be used to guide decision‐making in dogs with EFB.     

Force Plate Gait Analysis in Doberman Pinschers with and without Cervical Spondylomyelopathy

Background

The most accepted means of evaluating the response of a patient with cervical spondylomyelopathy (CSM) to treatment is subjective and based on the owner and clinician's perception of the gait.

Objective

To establish and compare kinetic parameters based on force plate gait analysis between normal and CSM‐affected Dobermans.

Animals

Nineteen Doberman Pinschers: 10 clinically normal and 9 with CSM.

Methods

Force plate analysis was prospectively performed in all dogs. At least 4 runs of ipsilateral limbs were collected from each dog. Eight force platform parameters were evaluated, including peak vertical force (PVF) and peak vertical impulse (PVI), peak mediolateral force (PMLF) and peak mediolateral impulse, peak braking force and peak braking impulse, and peak propulsive force (PPF) and peak propulsive impulse. In addition, the coefficient of variation (CV) for each limb was calculated for each parameter. Data analysis was performed by a repeated measures approach.

Results

PMLF (P = .0062), PVI (P = .0225), and PPF (P = .0408) were found to be lower in CSM‐affected dogs compared with normal dogs. Analysis by CV as the outcome indicated more variability in PVF in CSM‐affected dogs (P = 0.0045). The largest difference in the CV of PVF was seen in the thoracic limbs of affected dogs when compared with the thoracic limbs of normal dogs (P = 0.0019).

Conclusions and Clinical Importance

The CV of PVF in all 4 limbs, especially the thoracic limbs, distinguished clinically normal Dobermans from those with CSM. Other kinetic parameters less reliably distinguished CSM‐affected from clinically normal Dobermans.     

Renal resistive index in 55 dogs with degenerative mitral valve disease

Background

Azotemia occurs frequently in dogs with degenerative mitral valve disease (DMVD). It could indicate changes in renal hemodynamics.

Hypothesis/Objectives

To assess the renal resistive index (RI) in dogs with DMVD, and the statistical link between heart failure class, azotemia, echo‐Doppler parameters, several plasma variables, and RI.

Animals

Fifty‐five dogs with naturally occurring DVMD were used (ISACHC class 1 [n = 28], 2 [n = 19], and 3 [n = 8]).

Methods

Observational, blinded study, performed under standardized conditions. Physical examination, renal ultrasonography, and echo‐Doppler examinations were performed in awake dogs. The RI of the renal, interlobar, and arcuate arteries were measured. Plasma creatinine, urea, and N‐terminal pro‐B‐type natriuretic peptide concentrations (NT‐proBNP) were determined. Statistical links between variables and RI were tested by means of a general linear model.

Results

Although the RI of renal and arcuate arteries were unaffected by ISACHC class, the left interlobar RI increased (P < .001) from 0.62 ± 0.05 (mean ± SD) in class 1 to 0.76 ± 0.08 in class 3. It was also higher (P < .001) in azotemic (0.74 ± 0.08) than in non‐azotemic (0.62 ± 0.05) dogs. Similar findings were observed for right interlobar RI. Univariate analysis showed a positive statistical link between NT‐proBNP (P = .002), urea (P < .001), creatinine (P = .002), urea‐to‐creatinine ratio (P < .001), left atrium‐to‐aorta ratio (P < .001), regurgitation fraction (P < .001), systolic pulmonary arterial pressure (P < .001), shortening fraction (P = .035), and RI.

Conclusion and Clinical Importance

In dogs with DMVD, interlobar RI increases with heart failure severity and azotemia but a cause and effect relationship remains to be established.     

Noninvasive Clinical Assessment of Systolic Torsional Motions by Two‐Dimensional Speckle‐Tracking Echocardiography in Dogs with Myxomatous Mitral Valve Disease

Background

Left ventricular torsional motion plays an important role for effective pump function. However, noninvasive clinical assessment of torsional deformations by two‐dimensional speckle‐tracking echocardiography (2D‐STE) in dogs with myxomatous mitral valve disease (MMVD) has not been reported.

Hypothesis

Left ventricular torsion is determined by the native orientation of the helical myocardial fibers, such that it might provide better assessment of myocardial function than conventional methods.

Animals

Sixty‐seven client‐owned dogs with MMVD were classified into 3 classes based on the International Small Animal Cardiac Health Council classification and 16 weight‐ and age‐matched healthy dogs.

Methods

Dogs were examined for myocardial deformations by 2D‐STE and were evaluated for peak systolic rotation and rotation rate at each basal and apical view. Dogs also were evaluated for peak systolic torsion and torsion rate.

Results

Peak systolic torsion was higher in class II than in class I (P < .001) dogs. Peak systolic torsion was lower in class III than in class II (P = .001) dogs and controls (P = .003).

Conclusions and Clinical Importance

Torsional deformations assessed by 2D‐STE differed among clinical classes of MMVD. Myocardial torsional deformations by 2D‐STE may provide more detailed assessment of contractile function in dogs with MMVD.     

Effects of nutritional support on hospital outcome in dogs and cats

Objective – Investigate the effects of assisted nutritional support on hospital outcome in dogs and cats, and the relationship between hospital outcome and energy intake, body condition score (BCS), physical status score, and type of nutritional support used. Design – Retrospective analysis of hospitalized animals. Setting – Teaching Veterinary Hospital. Animals – Four hundred and sixty‐seven dogs and 55 cats. Interventions – Routine clinical nutritional support. Measurements and Main Results – The following variables were recorded for each animal: energy intake, body weight at admission and discharge, BCS, physical status score, and type of nutritional support used. Disease severity was negatively associated with hospital outcome and energy intake (P=0.009). Energy intake was positively associated with hospital discharge (P<0.001). Outcome may be related to BCS, with discharge rates of 73% for animals with low BCS, and 84.7% for those at an ideal BCS or overweight (P=0.04). Sixty‐four percent of animals showed voluntary food intake (92.9% were discharged), 19.0% received enteral support (71.8% were discharged), 7.0% were forced fed (75.0% were discharged), 6.0% received parenteral support (61.9% were discharged), and 4.0% did not receive calories (38.4% were discharged), suggesting a possible relationship between the type of nutritional support, energy intake, and outcome (P=0.009). Conclusions – Energy supply, even if modest and close to resting energy requirements appears to be positively associated with hospital discharge. However, disease severity was the main negative factor on outcome and also had a negative effect on energy intake, making it difficult to separate the effects of both factors when interpreting hospital discharge. Thin animals with low BCS had greater mortality.     

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.     

Effects of 6% Tetrastarch and Lactated Ringer's Solution on Extravascular Lung Water and Markers of Acute Renal Injury in Hemorrhaged,Isoflurane‐Anesthetized Healthy Dogs

Background

Tetrastarch can cause acute kidney injury (AKI) in humans with sepsis, but less likely to result in tissue edema than lactated Ringer's solution (LRS).

Objectives

Compare effects of volume replacement (VR) with LRS and 6% tetrastarch solution (TS) on extravascular lung water (EVLW) and markers of AKI in hemorrhaged dogs.

Animals

Six healthy English Pointer dogs (19.7–35.3 kg).

Methods

Prospective crossover study. Animals underwent anesthesia without hemorrhage (Control). Two weeks later, dogs hemorrhaged under anesthesia on 2 occasions (8‐week washout intervals) and randomly received VR with LRS or TS at 3 : 1 or 1 : 1 of shed blood, respectively. Anesthesia was maintained until 4 hour after VR for EVLW measurements derived from transpulmonary thermodilution cardiac output. Neutrophil gelatinase‐associated lipocalin (NGAL) and creatinine concentrations in plasma and urine were measured until 72 hour after VR.

Results

The EVLW index (mL/kg) was lower at 1 hour after TS (10.0 ± 1.9) in comparison with controls (11.9 ± 3.4, P = 0.04), and at 4 hour after TS (9.7 ± 1.9) in comparison with LRS (11.8 ± 2.7, P = 0.03). Arterial oxygen partial pressure‐to‐inspired oxygen fraction ratio did not differ among treatments from 0.5 to 4 hour after VR. Urine NGAL/creatinine ratio did not differ among treatments and remained below threshold for AKI (120,000 pg/mg).

Conclusions and Clinical Importance

Although TS causes less EVLW accumulation than LRS, neither fluid produced evidence of lung edema (impaired oxygenation). Both fluids appear not to cause AKI when used for VR after hemorrhage in healthy nonseptic dogs.     

Serum 25‐hydroxyvitamin D concentrations in dogs – correlation with health and cancer risk

25‐hydroxyvitamin D (25(OH)D) is important in bone health as well as many diseases including cancer. Supplementation may increase responsiveness of cancer cells to chemotherapy. Serum 25(OH)D, intact parathyroid hormone (iPTH) and canine C‐reactive protein (c‐CRP) were measured in healthy dogs and dogs with haemoabdomen. Regression analysis determined optimal 25(OH)D concentrations. In healthy dogs (n = 282), mean iPTH concentrations correlated inversely (r² = 0.88, P < 0.001) to 25(OH)D concentrations. Variation in both iPTH and c‐CRP plateaued at 25(OH)D concentrations of 100–120 ng mL^?1. Haemoabdomen dogs (n = 63, 43 malignant and 20 benign) had 25(OH)D concentrations ranging from 19.4 to >150 ng mL^?1. Relative risk of cancer increased with decreasing 25(OH)D concentrations [RR = 3.9 for 25(OH)D below 40 ng mL^?1 (P = 0.0001)]. Serum 25(OH)D concentrations in dogs vary widely, and are influenced by dietary VitD content. Serum vitD measurement can identify dogs for which supplementation may improve health and response to cancer therapy.     

Quantification of plasma DNA as a prognostic indicator in canine lymphoid neoplasia

Dogs have a similar incidence of spontaneous cancers as people, and a noninvasive test to monitor disease status in dogs would be of great value. Humans with cancer often have increased levels of cell‐free circulating DNA in their plasma, which has shown promise for diagnosis, prognosis and detection of residual disease. We hypothesized that dogs with cancer have increased circulating DNA compared with healthy dogs or dogs with non‐neoplastic diseases. Plasma DNA was measured in 40 healthy dogs, 20 dogs with non‐neoplastic diseases and 80 dogs with cancer. The reference interval for plasma DNA in healthy dogs was 1–15 ng mL^?1. Dogs with lymphoma and lymphoid leukaemia had significantly higher concentrations (range: 0–91 ng mL^?1, P < 0.0001). Antigen receptor rearrangement assays suggest that plasma DNA had the same clonality as the primary lymphoid tumours. Dogs with lymphoid neoplasia and plasma DNA >25 ng mL^?1 had shorter remission times than those with < 25 ng mL^?1 (P= 0.0116). In contrast to humans, where increased plasma DNA is seen in many diseases, dogs with nonlymphoid malignancies and non‐neoplastic diseases had plasma DNA concentrations similar to healthy dogs. This study shows that a portion of dogs with lymphoid neoplasia have increased tumour‐derived plasma DNA, which serves as a negative prognostic indicator.     

Evaluation of reticulocyte hemoglobin content (RET‐He) in the diagnosis of iron‐deficient erythropoiesis in dogs

Background

Reticulocyte hemoglobin content provided by the Siemens ADVIA (CHr) is an established marker of iron deficiency. The IDEXX ProCyte Dx hematology analyzer now provides a similar variable, reticulocyte hemoglobin equivalent (RET‐He).

Objectives

The objective was to evaluate RET‐He and its diagnostic utility in dogs, and to calculate a cutoff value for diagnosing iron‐deficient erythropoiesis (IDE). Furthermore, the prevalence of RET‐He values below this cutoff value was established.

Methods

One hundred and seventy‐one CBCs of healthy dogs were used to establish a RI. Stability of RET‐He was evaluated by repeated measurements over 48 hours (n = 10). The 25‐run coefficient of variation (CV) was calculated, and correlation and bias between measurements of RET‐He and CHr were assessed (n = 190). A cutoff value for diagnosing IDE was calculated. The utility of RET‐He in the detection of IDE was evaluated in 123 dogs. The prevalence of low RET‐He values was assessed retrospectively in a multicenter study (2012–2014) under participation of 7 veterinary clinics.

Results

Reticulocyte hemoglobin equivalent with an RI of 22.2 to 28.6 pg was statistically stable over 48 hours (P = .10). The CV was 1.8%. A fair correlation (ρ = 0.74) between RET‐He and CHr with a small bias of ?0.6 pg was found. The cutoff value for diagnosing IDE was 20.9 pg (sensitivity: 85%; specificity: 99%). The prevalence of RET‐He values below 20.9 pg was 10.3% (1084/10,553 dogs).

Conclusions

RET‐He on the ProCyte Dx is a precise screening tool in dogs to detect iron‐deficient erythropoiesis.