Association between initial systolic blood pressure and risk of developing a uremic crisis or of dying in dogs with chronic renal failure

Association between systolic blood pressure and target organ damage in naturally occurring cases of systemic hypertension in the dog

Chronic elevation in the systolic blood pressure (SBP) adversely affects the lifespan in the dog by causing injury to the eye, heart, kidney and brain. Understanding the association between SBP and target organ damage (TOD) helps in risk categorization and treatment planning. Therefore, a prospective study was undertaken to find the association between SBP and renal resistive index (RI) in naturally occurring cases of canine systemic hypertension. Based on the ACVIM guidelines 2018, dogs (n=135) were categorized into four risk groups of SBP, viz., A (minimal), B (low), C (moderate), and D (high). Ophthalmoscopy and echocardiography were used to assess ocular and cardiac changes, respectively. Nephrosonography, urinalysis, and RI were used to assess kidney damage. Odds ratio (OR) was used to quantify the risk of TOD for different categories of SBP. One-way Anova with Tukey's post-hoc test was used to test the effect of different SBP risk groups on urine protein creatinine ratio (UPC) and RI as well as the effect of number of TOD on the RI. Pearson's correlation test was done to see the relation of SBP with UPC and RI. Tortuous retinal vessels were common in group B with an OR of 11 (95% CI: 0.59-207). Retinal hemorrhage and left ventricular hypertrophy were common in group D with an OR of 13 (95% CI: 0.67-234) and 11 (95% CI: 0.61-207), respectively. A significant strong positive correlation of SBP with UPC (R2=0.65) and RI (R2=0.58) was observed. The renal RI significantly increased when the number of TOD was ≥ 2. It was concluded that SBP and RI are associated with the number and severity of TOD and might be valuable in risk classification in hypertensive dogs.

Differentiation of stable kidney function versus progressive dysfunction in dogs

BACKGROUND

Circulating creatinine and symmetric dimethylarginine (SDMA) are biomarkers of kidney function that have been used variously to define stable vs progressive chronic kidney disease (CKD). Slope monitoring of inverse biomarker values (creatinine-1 or SDMA-1 ) has shown promise, but quantitative criteria to distinguish stable vs progressive CKD using this approach are lacking.

OBJECTIVE

Assessment of creatinine-1 and SDMA-1 slope cutoffs to distinguish stable vs progressive CKD.

ANIMALS

One hundred ten clinically healthy university staff-owned dogs and 29 male colony dogs with progressive X-linked hereditary nephropathy (XLHN).

METHODS

Retrospective analysis combining 2 prospective observational studies, 1 tracking kidney function biomarkers in healthy dogs (HDs) to a maximum of 3 years, and 1 tracking kidney function biomarkers in male colony dogs with progressive XLHN to a maximum of 1 year. The minimum slope of creatinine-1 or SDMA-1 as measured using the IDEXX SDMA test from HD was assigned as the slope cutoff for stable kidney function.

RESULTS

The stable vs progressive slope cutoff was -0.0119 week × dL/mg for creatinine-1 and -0.0007 week × dL/μg for SDMA-1 .

CONCLUSIONS AND CLINICAL IMPORTANCE

In the studied CKD population, progressive dysfunction can be distinguished from stable kidney function by using the slope of creatinine-1 or SDMA-1 . These criteria may serve to characterize CKD in other cohorts of dogs and to establish guidelines for degrees of progression rate in dogs with naturally occurring CKD.

Ultrasonographic kidney length-to-abdominal aortic diameter for the diagnosis of feline chronic kidney disease: A preliminary study

Background and Aim

Chronic kidney disease (CKD) is one of the most important diseases in cats. This study aimed to compare the ultrasonographic kidney length-to-abdominal aortic diameter (K/AO) ratio between healthy and CKD cats and investigate the correlation between K/AO and blood results.

Materials and Methods

Fifteen healthy cats and 15 CKD cats were included in this clinically prospective study. All cats were evaluated for radiographic and ultrasonographic K, radiographic K-to-second lumbar length ratio (K/L2), and K/AO, indirect systolic blood pressure and plasma creatinine (Cr), blood urea nitrogen (BUN), and symmetric dimethyl arginine (SDMA).

Results

The radiographic and ultrasonographic kidney lengths of CKD were significantly shorter than those of healthy cats (p < 0.05 and p < 0.05, respectively). The average K/L2 and K/AO were significantly lower in CKD than in healthy cats (p < 0.01 and p < 0.001, respectively). The K/AO had a strong negative correlation with plasma Cr (r = -0.7682, p < 0.0001), BUN (r = -0.6175, p < 0.001), and SDMA (r = -0.589, p < 0.001). However, K/L2 had a moderate negative correlation with plasma Cr (r = -0.5866, p < 0.001), BUN (r = -0.4884, p < 0.01), and SDMA (r = -0.5404, p < 0.01). The optimal cutoff value of K/AO (<10.71) had higher sensitivity and specificity than K/L2 for identifying feline CKD.

Conclusion

Kidney length-to-abdominal aortic diameter could be a better and more promising parameter than the K/L2 ratio for evaluating kidney size in cats with CKD.

Upregulated miR-194-5p suppresses retinal microvascular endothelial cell dysfunction and mitigates the symptoms of hypertensive retinopathy in mice by targeting SOX17 and VEGF signaling

BACKGROUND

Hypertensive retinopathy (HR) is a retinal disease that may lead to vision loss and blindness. Sex-determining region Y (SRY)-box (SOX) family transcription factors have been reported to be involved in HR development. In this study, the role and upstream mechanism of SRY-box transcription factor 17 (SOX17) in HR pathogenesis were investigated.

METHODS

SOX17 and miR-194-5p levels in Angiotensin II (Ang II)-stimulated human retinal microvascular endothelial cells (HRMECs) and retinas of mice were detected by RT-qPCR. SOX17 protein level as well as levels of tight junction proteins and vascular endothelial growth factor (VEGF) signaling-associated proteins were quantified by western blotting. Tube formation assays were performed to evaluate angiogenesis in HRMECs. The structure of mouse retinal tissues was observed by H&E staining. The interaction between miR-194-5p and SOX17 was confirmed by a luciferase reporter assay.

RESULTS

SOX17 was upregulated in HRMECs treated with Ang II. SOX17 knockdown inhibited angiogenesis in Ang II-stimulated HRMECs and increased tight junction protein levels. Mechanically, SOX17 was targeted by miR-194-5p. Moreover, miR-194-5p upregulation restrained angiogenesis and increased tight junction protein levels in Ang II-treated HRMECs, and the effect was reversed by SOX17 overexpression. MiR-194-5p elevation inactivated VEGF signaling via targeting SOX17. miR-194-5p alleviated pathological symptoms of HR in Ang II-treated mice, and its expression was negatively correlated with SOX17 expression in the retinas of model mice.

CONCLUSIONS

MiR-194-5p upregulation suppressed Ang II-stimulated HRMEC dysfunction and mitigates the symptoms of HR in mice by regulating the SOX17/VEGF signaling.

Effect of calcifediol supplementation on renin-angiotensin-aldosterone system mediators in dogs with chronic kidney disease

Background

Chronic kidney disease (CKD) leads to low serum concentrations of vitamin D metabolites. Thus, hypovitaminosis D associated with CKD might contribute to disease progression via increased concentration of renin angiotensin aldosterone system (RAAS) mediators.

Objectives

To evaluate whether supplementation with calcifediol affects equilibrium concentrations of selected mediators of the RAAS. We hypothesized that vitamin D supplementation will decrease concentration of circulating RAAS mediators in dogs with CKD.

Animals

Six client‐owned adult dogs with IRIS Stage 2 and 3 CKD.

Methods

Prospective study. Serum 25‐hydroxyvitamin D (25[OH]D), 1,25‐dihydroxyvitamin D (1,25[OH]₂D), 24,25‐dihydroxyvitamin D (24,25[OH]₂D), RAAS mediators (angiotensin I/II/III/IV/1‐5/1‐7, and aldosterone), and surrogate angiotensin converting enzyme (ACE) activity (calculated by the ratio of angiotensin II to angiotensin I) were evaluated at baseline, after 3 months of calcifediol supplementation, and 2 months after discontinuing administration of supplement.

Results

All serum vitamin D metabolite concentrations increased significantly by month 3 (P < .001): 25(OH)D (median 250 ng/mL; range, 204‐310), compared to baseline (median 43.2 ng/mL; range, 33.8‐58.3 ng/mL); 1,25(OH)₂D (median 66.1 pg/mL; range, 57.3‐88.1 pg/mL) compared to baseline (median 35.2 pg/mL; range, 29.3‐56.7 pg/mL); 24,25(OH)₂D (median 68.4 ng/mL; range, 22.1‐142.0 ng/mL) compared to baseline (median 14.4 ng/mL; range, 9.0‐21.3 ng/mL). Calculated ACE activity was significantly lower at month 3 (median 0.5; range, 0.4‐1.0) compared to baseline (median 0.7; range, 0.6‐1.3; P = .01). There were no significant differences in any of the evaluated RAAS variables at any other time‐point.

Conclusions and Clinical Importance

Short‐term calcifediol supplementation in this small group of CKD dogs appeared to decrease ACE activity.

The Contribution of Gut Microbiota and Endothelial Dysfunction in the Development of Arterial Hypertension in Animal Models and in Humans

The maintenance of the physiological values of blood pressure is closely related to unchangeable factors (genetic predisposition or pathological alterations) but also to modifiable factors (dietary fat and salt, sedentary lifestyle, overweight, inappropriate combinations of drugs, alcohol abuse, smoking and use of psychogenic substances). Hypertension is usually characterized by the presence of a chronic increase in systemic blood pressure above the threshold value and is an important risk factor for cardiovascular disease, including myocardial infarction, stroke, micro- and macro-vascular diseases. Hypertension is closely related to functional changes in the endothelium, such as an altered production of vasoconstrictive and vasodilator substances, which lead to an increase in vascular resistance. These alterations make the endothelial tissue unresponsive to autocrine and paracrine stimuli, initially determining an adaptive response, which over time lead to an increase in risk or disease. The gut microbiota is composed of a highly diverse bacterial population of approximately 10¹⁴ bacteria. A balanced intestinal microbiota preserves the digestive and absorbent functions of the intestine, protecting from pathogens and toxic metabolites in the circulation and reducing the onset of various diseases. The gut microbiota has been shown to produce unique metabolites potentially important in the generation of hypertension and endothelial dysfunction. This review highlights the close connection between hypertension, endothelial dysfunction and gut microbiota.

Association between serum fibroblast growth factor-23 concentration and development of hyperphosphatemia in normophosphatemic dogs with chronic kidney disease

BACKGROUND

Fibroblast growth factor (FGF)-23 is increased first in the sequence of changes associated with chronic kidney disease (CKD)-mineral and bone disorder. Thus, its measurement may serve as a predictive indicator of incident hyperphosphatemia.

OBJECTIVES

To investigate whether serum FGF-23 concentration in normophosphatemic dogs with CKD is associated with the risk of the subsequent development of hyperphosphatemia and CKD progression.

ANIMALS

Forty-two normophosphatemic dogs with CKD.

METHODS

Blood samples and medical records were retrospectively investigated. Hyperphosphatemia was defined as a serum phosphorous concentration >5.0 mg/dL. Progression was defined as a >1.5-fold increase in serum creatinine concentration. The time periods and hazard ratios for these outcomes were assessed using Kaplan-Meier analysis, log-rank test, and univariate Cox regression analysis. The variables associated with the outcomes in the univariate analysis were included in the multivariate Cox regression model with backward selection.

RESULTS

Serum FGF-23 concentration >528 pg/mL was associated with a shorter time to development of hyperphosphatemia (P < .001) and CKD progression (P < .001). In multiple Cox regression analysis, increased FGF-23 concentration remained a significant variable associated with these outcomes (P < .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

Increased FGF-23 concentration in normophosphatemic dogs with CKD was associated with significant risk of development of hyperphosphatemia, independent of CKD stage, and of the progression of CKD. Future research focusing on whether interventions that decrease FGF-23 secretion will slow the development of hyperphosphatemia and CKD progression is needed.

Evaluation of the progression of non-azotemic proteinuric chronic kidney disease in dogs

Proteinuria is a recognized risk factor for progression of canine chronic kidney disease (CKD). However, the prognosis of non-azotemic proteinuric CKD in dogs has been studied only to a limited extent. Moreover, the degree to which proteinuria should be decreased to delay CKD progression remains unknown. The purposes of this study were (1) to identify factors associated with disease progression and (2) to investigate the degree of proteinuria, albuminuria, and blood pressure during the course of treatment associated with the progression using time-averaged urine protein:creatinine ratio (UPC) and urine albumin:creatinine ratio (UAC) in canine non-azotemic proteinuric CKD. Twenty-one dogs with non-azotemic proteinuric CKD were included in the study. High UPC and UAC were associated with CKD progression (P < .05). Time-averaged high UPC and UAC were significantly related to progression (P < .05). The cutoff values of these time-averaged parameters for predicting the progression were 4.1 and 2.0, respectively. In dogs with non-azotemic proteinuric CKD, more severe proteinuria and albuminuria were associated with progression. The present study suggests that because UPC ≥ 4.1 and UAC ≥ 2.0 during treatment were associated with a faster progression of non-azotemic proteinuric CKD, therapeutic intervention is warranted.

Effects of telmisartan on proteinuria and systolic blood pressure in dogs with chronic kidney disease

Renal proteinuria is associated with promoted renal dysfunction and a shorter survival period in dogs with chronic kidney disease (CKD). Renin angiotensin- aldosterone system inhibitors are primarily used to treat renal proteinuria. In this retrospective, open-label study, we aimed to evaluate the anti-proteinuric and anti-hypertensive effects of telmisartan (angiotensin II receptor blocker) in dogs with proteinuric CKD. A total of 28 dogs with proteinuric CKD were included in the study, all dogs received telmisartan 1 mg/kg q24h, PO. The urine protein-to-creatinine ratio (UPC), urine albumin-to-creatinine ratio (UAC) and systolic blood pressure (SBP) decreased significantly after telmisartan administration (P < 0.05). The median rate of change in UPC, UAC and SBP at Day 120 were - 65.1%, -75.9% and - 9.7%. Ten dogs (36.7%) achieved UPC < 1.0 at Day 120, of which six dogs had UPC < 0.5. A reduction of UPC to ≥50% was achieved in 10 dogs (36%) at Day 45 and 17 dogs (61%) at Day 120. Seventeen dogs (61%) had hypertension at baseline, of which 10 dogs (59%) had SBP < 160 mmHg at Day 120. Two-way repeated measures analysis of variance did not attribute the observed changes in SBP, UPC or UAC to feeding with a renal diet. In conclusion, telmisartan therapy provides anti-proteinuric and anti-hypertensive effects in dogs with proteinuric CKD.

Ultrasonographic assessment of abdominal aortic elasticity in hypertensive dogs

Background

Systemic hypertension (SH) is a persistent and pathological increase in arterial blood pressure (BP). Chronic SH leads to an increase in aortic (Ao) stiffness, and measuring Ao elasticity is useful for estimating Ao stiffness in humans. Currently, no literature in veterinary medicine describes noninvasive assessment of abdominal Ao elasticity in dogs with SH.

Objective

Compare ultrasonographic‐derived abdominal Ao strain (AoSt) between hypertensive (HT) and normotensive (NT) dogs.

Animals

Fifty privately‐owned dogs with clinical signs, conditions, or both potentially associated with SH.

Methods

Prospective observational case‐control study. Aortic stiffness was estimated by calculating AoSt as follows: AoSt = ([AoDs − AoDd]/AoDd) × 100, where AoDs and AoDd are the Ao diameter in systole and in diastole, respectively. Aortic stiffness was calculated from 2 different Ao transverse sections, the first caudal to the left renal artery (K_AoSt), and the second cranial to the external iliac arteries (I_AoSt).

Results

Thirty‐two dogs were included in the HT group and 18 in the NT group. Both K_AoSt and I_AoSt in HT dogs were significantly lower (P < .05) than in NT dogs (7.4 ± SD 3.6) vs 10.3 (±3.8) and 5.7 (interquartile range [IQR], 3.9‐7.5) vs 8.1 (IQR, 7‐10.3), respectively. Only K_AoSt was significantly influenced by age.

Conclusions and Clinical Importance

Ultrasonographic Ao elasticity assessment was feasible to compare HT and NT dogs. Results indicated that K_AoSt and I_AoSt indices can be used to assess SH‐related Ao stiffness, especially when indirect BP measurements are inconsistent or inaccurate. Additional studies to assess the AoSt in healthy dogs of various ages are needed.

Hypertension, retinopathy, and acute kidney injury in dogs: A prospective study

BACKGROUND

Systemic hypertension (SH) is a potential complication of acute kidney injury (AKI) in dogs.

OBJECTIVE

To describe the prevalence of SH and hypertensive retinopathy in dogs with AKI, to investigate the relationship between SH and severity of AKI and to assess possible factors associated with SH.

ANIMALS

Fifty-two dogs with AKI.

METHODS

Prospective observational study of dogs presenting to a tertiary referral center that fulfilled the International Renal Interest Society (IRIS) guidelines for the diagnosis of AKI. Systolic blood pressure measurement, urine protein/creatinine ratio (UPCR), urine output, presence of hypertensive retinopathy and fluid overload (FO), survival to discharge and duration of hospitalization were subsequently assessed. The prevalence of SH was calculated and the relationship between SH and recorded factors was examined by nonparametric statistics.

RESULTS

The prevalence of SH (≥160 mm Hg) on admission or during hospitalization was 75% (39/52) and in 56% (22/39) of cases this was severe (≥180 mm Hg). Sixteen percent (7/43) of dogs had evidence of hypertensive retinopathy and 77% (24/31) dogs had UPCR >0.5. Forty-two percent (22/52) dogs had FO on admission or during hospitalization. There was no association between SH and IRIS AKI grade, oligo/anuria, survival to discharge, duration of hospitalization or proteinuria. Dogs with FO on presentation were more likely to be hypertensive at admission compared to dogs without FO (P = .02). Dogs that did not survive to discharge were more likely to have FO (P = .007).

CONCLUSIONS AND CLINICAL IMPORTANCE

Systemic hypertension is common in dogs with AKI. Systemic hypertension might be associated with FO, which itself is associated with nonsurvival. Monitoring for SH and FO is therefore warranted in dogs with AKI.

Clinicopathologic characteristics, pathology, and prognosis of 77 dogs with focal segmental glomerulosclerosis

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) is a common cause of nonimmune complex glomerulopathy and the prognosis and clinicopathologic findings associated with this condition have not been described in dogs.

OBJECTIVE

To characterize the presentation and identify clinical factors associated with the survival of dogs with FSGS.

ANIMALS

Seventy-seven dogs diagnosed with FSGS based on evaluation of renal biopsy samples submitted to the International Veterinary Renal Pathology Service.

METHODS

Retrospective review of medical records of dogs biopsied for evaluation of proteinuria between January 2015 and May 2017.

RESULTS

The incidence of FSGS among all dogs biopsied for proteinuria was 26%. Significantly more females (48; 62.3%) than males (29; 37.7%) were affected (P = .04). At the time of biopsy, median serum creatinine concentration (SCr) was 1.2 mg/dL (range, 0.3-8.7), median serum albumin concentration (Alb) was 2.8 g/dL (range, 1.1-4.6), median systolic blood pressure was 153.5 mm Hg (range, 95-260), and median urine protein : creatinine ratio was 5.9 (range, 1.4-22). Median survival time after biopsy was 258 days (range, 26-1003) for dogs that died from all causes (n = 32). Factors that were associated with a shorter survival time included SCr ≥ 2.1 mg/dL (P < .01) and Alb < 2 g/dL (P < .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

Most dogs with FSGS were female, and although commonly hypertensive, azotemia, severe hypoalbuminemia and ascites or edema were observed infrequently. Variables significantly associated with survival time were SCr and Alb.

Short term impacts of meglumine antimoniate treatment on kidney function in dogs with clinical leishmaniosis

This study examines correlations among serum proteins, clinical score, body weight and kidney function biomarkers after a standard treatment course (meglumine antimoniate plus allopurinol) in twelve Canine leishmaniosis (CanL) patients at the three times points pre treatment, after treatment and after the end of treatment. The laboratory variables measured were those used for the follow-up of sick dogs along with biomarkers of kidney function: glomerular filtration rate (GFR), creatinine (Cr), urea, calcium, inorganic phosphorus, urine specific gravity (USG) and urine protein to creatinine ratio (UPC). Arterial blood pressure (systolic blood pressure, SBP), clinical score (CS) and weight were also monitored over the study period. At Tp0, GFR was within the normal range in most dogs. Hyperfiltration was detected in three patients and hypofiltration in one. In dogs showing hyperfiltration, this factor remained in the non-azotemic range over the whole study period. After treatment normal filtration values were recovered. Meglumine antimoniate did not modify GFR or USG. A significant reduction in UPC was recorded. In all dogs, clinical scores improved. Negative correlation was found between GFR and Cr, UPC and albumin (Alb) and CS and Alb, while positive correlation was detected between UPC and total globulins (GlobT), CS and GlobT, UPC and total solids (TS), SBP and CS and SBP and UPC. Our findings indicate no impacts on kidney function of the treatment of CanL with meglumine antimoniate, as no effects were produced on GFR or USG. Treatment was effective and found to reduce UPC which could suggest improved glomerular injury.

ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats

An update to the 2007 American College of Veterinary Internal Medicine (ACVIM) consensus statement on the identification, evaluation, and management of systemic hypertension in dogs and cats was presented at the 2017 ACVIM Forum in National Harbor, MD. The updated consensus statement is presented here. The consensus statement aims to provide guidance on appropriate diagnosis and treatment of hypertension in dogs and cats.

Effects of Benazepril on Survival of Dogs with Chronic Kidney Disease: A Multicenter, Randomized, Blinded, Placebo-Controlled Clinical Trial

BACKGROUND

Chronic kidney disease (CKD) is an important cause of morbidity and mortality in dogs.

OBJECTIVE

To evaluate the efficacy in prolonging survival and safety of benazepril administration to dogs with CKD.

ANIMALS

Forty-nine client-owned dogs with CKD.

METHODS

Dogs were randomized to benazepril (0.25 to <0.5 mg/kg) or placebo once daily for up to 2 years in a prospective, multicenter, blinded clinical trial. The primary endpoint variable was the renal survival time, defined as the time from inclusion in the study to the treatment failure endpoint of death or euthanasia or need for administration of parenteral fluids related to renal failure.

RESULTS

No benefit of benazepril versus placebo was detected for renal survival time in all dogs; median (95% confidence interval (CI)) survival times were 305 (53-575) days in the benazepril group and 287 (152-not available) in the placebo group (P = .53). Renal survival times were not significantly longer with benazepril compared to placebo for subgroups: hazard ratios (95% CI) were 0.50 (0.21-1.22) with P = .12 for initial urine protein-to-creatinine ratio (UPC) >0.5, and 0.38 (0.12-1.19) with P = .080 for initial UPC >0.5 plus plasma creatinine ≤440 μmol/L. Proteinuria, assessed from the UPC, was significantly (P = .0032) lower after treatment with benazepril compared to placebo. There were no significant differences between groups for clinical signs or frequencies of adverse events.

CONCLUSIONS AND CLINICAL RELEVANCE

Benazepril significantly reduced proteinuria in dogs with CKD. Insufficient numbers of dogs were recruited to allow conclusions on survival time.

The Renin-Angiotensin-Aldosterone System in Greyhounds and Non-Greyhound Dogs

Background

The renin‐angiotensin‐aldosterone system (RAAS) regulates blood pressure, electrolyte homeostasis, and renal function. Blood pressure, serum sodium concentrations, and urinary albumin excretion are higher in Greyhounds than other purebred and mixed‐breed dogs.

Hypothesis

Alterations in the RAAS in Greyhounds are associated with hemodynamic and clinicopathologic differences observed in the breed.

Animals

Clinically healthy Greyhound and non‐Greyhound dogs consecutively enrolled as blood donors (n = 20/group).

Methods

Prospective study. Standard chemical analysis was performed on serum and urine. Serum angiotensin‐converting enzyme (ACE) activity was determined by fluorometric assay. All other RAAS hormones were determined by radioimmunoassay. Symmetric dimethylarginine (SDMA) was measured by immunoassay. Measurements were compared to blood pressure and urine albumin concentration. Data are presented as mean ± SD or median, range.

Results

Serum creatinine (1.5 ± 0.2 vs 1.0 ± 0.1 mg/dL, P < .001), sodium (149, 147–152 vs 148, 146–150 mEq/L, P = .017), and SDMA (16.1 ± 2.9 vs 12.2 ± 1.8 μg/dL, P < .001) were significantly higher in Greyhounds versus non‐Greyhounds, respectively. Plasma renin activity (0.69, 0.10–1.93 vs 0.65, 0.27–2.93 ng/mL/h, P = .60) and ACE activity (4.5, 2.1–8.5 vs 4.6, 2.1–11.4 activity/mL; P = .77) were similar between groups and did not correlate with higher systolic pressures and albuminuria in Greyhounds. Plasma aldosterone concentration was significantly lower in Greyhounds versus non‐Greyhounds (11, 11–52 vs 15, 11–56 pg/mL, respectively, P = .002).

Conclusions and clinical importance

Basal RAAS activation did not differ between healthy Greyhounds and non‐Greyhounds. Lower aldosterone concentration in Greyhounds is an appropriate physiologic response to higher serum sodium concentration and blood pressure, suggesting that angiotensin II effects in the renal tubule predominate over those of aldosterone.

Hypertension and its correlation with renal lesions in dogs with leishmaniosis

To evaluate the prevalence of hypertension and its correlation with the severity of renal injury and proteinuria in dogs with leishmaniosis, sixty-six dogs were divided into two groups. Group 1 (G1) was composed of 54 dogs included in stage 1 of chronic kidney disease (CKD), and group 2 (G2) of twelve dogs in stages 2 and 3 of CKD. Prevalence of hypertension was 28.8%, comprising 22.2% of the dogs from G1 and 58.3% from G2 (P=0.011). The mean arterial blood pressure (BP) of dogs from G1 (135.7 ± 20.5) was lower than from G2 (170.0 ± 26.3) (P <0.001). Urine protein-creatinine ratio (UP/C) revealed values above 0.5 in 75.7% of the dogs, with 34% presenting hypertension. All dogs with hypertension had histopathological and laboratory evidence of glomerular disease. Although there was no statistically significant correlation between elevated BP and the severity of glomerular lesions (P=0.408), there was a statistically significant correlation between elevated BP and increased UP/C in the studied population (P=0.002). Thus, dogs with leishmaniosis and renal disease must be screened for the presence of hypertension so that treatment may be instituted as early as possible, in countries where treatment is allowed, to prevent the progression of renal damage.

Blood Pressure Measurements in 780 Apparently Healthy Cats

Background

Mean systolic blood pressure in apparently healthy cats has been reported as approximately 125 mmHg using direct assessment, but there is greater variability in reported values using indirect assessment. Increasing age and the white‐coat effect are associated with increased systolic blood pressure.

Hypothesis/Objectives

To report Doppler‐derived blood pressure measurements from a large population of apparently healthy cats and to assess epidemiologic factors associated with recorded blood pressures.

Animals

A total of 780 cats in rehoming centers enrolled in a screening program for heart murmurs and cardiac disease.

Methods

Cats were considered healthy based on history and physical examination. Cats with known hypertension, hyperthyroidism, or clinical signs of systemic disease and pregnant or nursing queens were excluded. After an acclimatization period, systolic blood pressure was measured using the Doppler sphygmomanometry method following the recommendations of the ACVIM Consensus Statement. General linear model analysis was performed to identify factors associated with variation in systolic blood pressure.

Results

Median (interquartile range, IQR) systolic blood pressure for the group was 120.6 (110.4–132.4) mmHg. Factors significantly associated with higher systolic blood pressure in a general linear model were increased age, increased nervousness, male sex, neutering, or history of being a stray. The model explained 29.2% of the variation in systolic blood pressure.

Conclusions and Clinical Importance

The age, demeanor, sex, neuter status and history of being a stray should be taken into account when assessing systolic blood pressure in apparently healthy cats.

ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease

PRACTICAL RELEVANCE

Chronic kidney disease (CKD) is one of the most commonly diagnosed diseases in older cats. In most cats, CKD is also a progressive disease and can be accompanied by a wide range of clinical and clinicopathological changes. These ISFM Consensus Guidelines have been developed by an independent panel of clinicians and academics to provide practical advice on the diagnosis and management of this complex disease.

CLINICAL CHALLENGES

Although CKD is a common clinical problem in cats, the manifestations of disease vary between individuals. Thus there is a need for careful and repeat evaluation of cats with CKD and adjustment of therapy according to individual needs. In addition to addressing problems arising from CKD and improving quality of life (QoL) for the patient, therapy may also target slowing the underlying progression of disease and hence prolonging life. While maintaining QoL is of paramount importance in our patients, this can be challenging when multiple therapies are indicated. In some cases it is necessary to prioritise therapy, given an understanding of what is likely to most benefit the individual patient.

EVIDENCE BASE

In preparing these Guidelines, the Panel has carefully reviewed the existing published literature, and has also graded the quality of evidence for different interventions to help to provide practical recommendations on the therapeutic options for feline CKD. This is a field of veterinary medicine that has benefited from some excellent published clinical research and further research findings will undoubtedly modify the recommendations contained in these Guidelines in the future.

Chronic Kidney Disease in Aged Cats: Clinical Features, Morphology, and Proposed Pathogeneses

Chronic kidney disease (CKD) is the most common metabolic disease of domesticated cats, with most affected cats being geriatric (>12 years of age). The prevalence of CKD in cats exceeds that observed in dogs, and the frequency of the diagnosis of CKD in cats has increased in recent decades. Typical histologic features include interstitial inflammation, tubular atrophy, and fibrosis with secondary glomerulosclerosis. In contrast to people and dogs, primary glomerulopathies with marked proteinuria are remarkably rare findings in cats. Although a variety of primary renal diseases have been implicated, the disease is idiopathic in most cats. Tubulointerstitial changes, including fibrosis, are present in the early stages of feline CKD and become more severe in advanced disease. A variety of factors-including aging, ischemia, comorbid conditions, phosphorus overload, and routine vaccinations-have been implicated as factors that could contribute to the initiation of this disease in affected cats. Factors that are related to progression of established CKD, which occurs in some but not all cats, include dietary phosphorus intake, magnitude of proteinuria, and anemia. Renal fibrosis, a common histologic feature of aged feline kidneys, interferes with the normal relationship between peritubular capillaries and renal tubules. Experimentally, renal ischemia results in morphologic changes similar to those observed in spontaneous CKD. Renal hypoxia, perhaps episodic, may play a role in the initiation and progression of this disease.

Plasma Vasoprotective Eicosanoid Concentrations in Healthy Greyhounds and Non-Greyhound Dogs

BACKGROUND

Hypertension and albuminuria often coexist in Greyhounds, suggesting generalized vascular dysfunction that could contribute to the development of a variety of diseases in this breed. Eicosanoid metabolites of arachidonic acid (AA) mediate endothelial function, vascular reactivity, and proteinuria in humans and in rodent models.

HYPOTHESIS

The eicosanoid profile of Greyhounds is shifted toward metabolites that promote vascular dysfunction, hypertension, and proteinuria.

ANIMALS

Healthy Greyhounds (n = 20) and non-Greyhound (n = 20) dogs that were consecutively enrolled in a blood donor program.

METHODS

Prospective study. Plasma eicosanoid metabolites were assayed by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI/MS) and compared to systolic blood pressure (SP) measurements and urine albumin concentration.

RESULTS

Isomers of hydroxyeicosatetraenoic acid (HETE) were higher in Greyhounds than non-Greyhounds (median, range in pmol/mL: 5(S)HETE 19.82, 8.55-32.95 versus 13.54, 4.33-26.27, P = .033; 8(S)HETE 9.39, 3.28-19.84 versus 5.80, 2.25-17.66, P = .002; 9(S)HETE 9.46, 2.43-13.79 versus 5.82, 1.50-17.16, P = .026; 12(S)HETE 10.17, 3.81-40.06 versus 7.24, 2.9-16.16, P = .022). Dihydroxyeicosatrienoic acid (DHET) isomers also were higher in Greyhounds compared to non-Greyhounds (mean ± SD in pmol/mL: 8,9DHET 5.78 ± 2.13 versus 4.03 ± 1.36, P = .004; 11,12DHET 11.98 ± 2.86 versus 8.90 ± 3.48, P = .004; 14,15DHET 7.23 ± 2.19 versus 5.76 ± 1.87, P = .028). Albuminuria correlated with total DHET (rs = 0.46, P = .003). SP was positively correlated with 11,12EET (rs = 0.42, P = .006) and 20(S)HETE (rs = 0.38, P = .017). SP and 8,9EET were inversely correlated (rs = -0.49, P = .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma eicosanoid profile in Greyhounds was consistent with activation of metabolic pathways known to promote vascular dysfunction and might contribute to higher blood pressures and albuminuria. Inhibition of these eicosanoid pathways should be evaluated as therapeutic targets in Greyhounds.

Cardiovascular-renal axis disorders in the domestic dog and cat: a veterinary consensus statement

OBJECTIVES

There is a growing understanding of the complexity of interplay between renal and cardiovascular systems in both health and disease. The medical profession has adopted the term "cardiorenal syndrome" (CRS) to describe the pathophysiological relationship between the kidney and heart in disease. CRS has yet to be formally defined and described by the veterinary profession and its existence and importance in dogs and cats warrant investigation. The CRS Consensus Group, comprising nine veterinary cardiologists and seven nephrologists from Europe and North America, sought to achieve consensus around the definition, pathophysiology, diagnosis and management of dogs and cats with "cardiovascular-renal disorders" (CvRD). To this end, the Delphi formal methodology for defining/building consensus and defining guidelines was utilised.

METHODS

Following a literature review, 13 candidate statements regarding CvRD in dogs and cats were tested for consensus, using a modified Delphi method. As a new area of interest, well-designed studies, specific to CRS/CvRD, are lacking, particularly in dogs and cats. Hence, while scientific justification of all the recommendations was sought and used when available, recommendations were largely reliant on theory, expert opinion, small clinical studies and extrapolation from data derived from other species.

RESULTS

Of the 13 statements, 11 achieved consensus and 2 did not. The modified Delphi approach worked well to achieve consensus in an objective manner and to develop initial guidelines for CvRD.

DISCUSSION

The resultant manuscript describes consensus statements for the definition, classification, diagnosis and management strategies for veterinary patients with CvRD, with an emphasis on the pathological interplay between the two organ systems. By formulating consensus statements regarding CvRD in veterinary medicine, the authors hope to stimulate interest in and advancement of the understanding and management of CvRD in dogs and cats. The use of a formalised method for consensus and guideline development should be considered for other topics in veterinary medicine.

Comparative clinical evaluation of Boerhavia diffusa root extract with standard Enalapril treatment in Canine chronic renal failure

BACKGROUND

Complementing herbal drugs with conservative modern treatment could improve renal condition in canine chronic renal failure (CRF).

OBJECTIVE

In this study, clinical evaluation of Boerhavia diffusa root extract was carried out in CRF in dogs in comparison with standard enalapril.

MATERIALS AND METHODS

A total of 20 dogs of mixed breeds suffering from CRF from 1 to 2 months were divided into two groups (n = 10) and treated as follows: Group I - Enalapril at 0.5 mg/kg p.o. once daily for 90 days + amoxicillin and cloxacillin at 25 mg/kg i.m. once daily for 1-week; Group II - B. diffusa root extract at 500 mg p.o per dog daily for 90 days. Both groups were maintained on a supportive fluid therapy. The data were analyzed using paired t-test and one-way ANOVA followed by Dunnett's post-hoc test.

RESULTS

CRF caused a significant (P < 0.05) increase in systolic and diastolic blood pressure, serum creatinine, urea nitrogen, sodium, potassium, phosphorus, urinary protein, alkaline phosphatase (ALP), and glutamyl transferase (GGT). A significant (P < 0.05) decrease in hemoglobin and total erythrocyte count (TEC) was also observed. Nephrosonography revealed indistinct corticomedullary junction, altered renal architecture, hyper-echoic cortex, medulla, and sunken kidneys. Both the treatments significantly (P < 0.05) reduced systolic and diastolic blood pressure by day 30. Serum Creatinine, urea nitrogen, phosphorus, urinary protein, ALP, and GGT showed significant (P < 0.05) reduction by day 60 in both the treatments. However, potassium levels were normalized only by B. diffusa root extract treatment by day 30. Both the treatments failed to show a significant improvement in nephrosonographic picture even after 90 days posttreatment.

CONCLUSION

In conclusion, the efficacy of B. diffusa root extract was comparable to standard enalapril treatment of CRF in dogs.

Magnetic resonance imaging appearance of hypertensive encephalopathy in a dog

A 16-year-old female spayed English Staffordshire terrier was presented for evaluation of a 10-month history of intermittent myoclonic episodes, and a one weeks history of short episodes of altered mentation, ataxia and collapse. Magnetic resonance imaging identified subcortical oedema, predominately in the parietal and temporal lobes and multiple cerebral microbleeds.

Serum biochemistry, indirect blood pressure measurements and magnetic resonance imaging abnormalities were consistent with hypertensive encephalopathy secondary to chronic kidney disease.

Influence of the observer's level of experience on systolic and diastolic arterial blood pressure measurements using Doppler ultrasonography in healthy conscious cats

The objective of this study was to determine the influence of the observer's level of experience on within- and between-day variability, and the percentage of successful systolic (SAP) and diastolic arterial blood pressure (DAP) measurements obtained by Doppler ultrasonography (DU) in awake cats. For this purpose, six healthy conscious cats were used and four observers with different levels of training performed 144 SAP and DAP measurements on 4 days using DU. Measurements were recorded five consecutive times, and mean values were used for statistical analysis. Only the two most skilled observers - a PhD student in cardiology and a Dipl ECVIM-CA (cardiology) - had within- and between-day coefficients of variation (CVs) for SAP ⩽16% (13-16%). Conversely, the two less experienced observers - a fifth-year student and an assistant - had high between-day CVs (61% and 73%). For DAP, only the most experienced observer (Dipl ECVIM-CA) succeeded in 100% of the attempts, with within- and between-day CVs of 11% and 4%, respectively. Conversely, DAP could not be measured by the other three observers in 8%, 19% and 56% of attempts (from the highest to the lowest level of experience); therefore, the corresponding CV values could not be calculated. In conclusion, SAP may be assessed using DU in healthy awake cats with good repeatability and reproducibility by a well-trained observer. Measurement of DAP is more difficult than of SAP, and needs a longer training period, which represents one of the limitations of DU in cats.

Comparison of forelimb and hindlimb systolic blood pressures and proteinuria in healthy Shetland Sheepdogs

Background

The prevalence of systemic hypertension (SHT) in Shetland Sheepdogs has not been reported.

Hypothesis/Objectives

SHT is common in Shetland Sheepdogs and positively correlated with proteinuria. Measurements of forelimb and hindlimb systolic arterial pressure (SAP) are comparable.

Animals

Seventy‐two clinically healthy, client‐owned Shetland Sheepdogs.

Methods

Forelimb and hindlimb SAP were recorded by Doppler ultrasonography. Proteinuria was quantified by urine dipstick, microalbuminuria, and protein:creatinine ratio (UPC). The relationship of UPC, anxiety, age, weight, and heart rate with forelimb SAP was evaluated.

Results

The mean forelimb and hindlimb SAP were 132 ± 20 and 118 ± 20 mmHg, respectively. The SAP exceeded 160 mmHg in 9 dogs, suggesting 13% prevalence of SHT. Four dogs had a UPC above 0.5; 2 of these had forelimb SAP exceeding 160 mmHg. Correlation of forelimb and hindlimb SAP was poor (r² = 0.09; P = .011). Bland–Altman plots revealed substantial bias (−14 mmHg) between limb measurements with clinically unacceptable 95% limits of agreement (−60 to 33 mmHg). There was no correlation between forelimb SAP and UPC (P = .06) or anxiety level (P = .49). Age (P < .0001) and heart rate (P = .038) were significant predictors of forelimb SAP; weight (P = .73) was not.

Conclusions

Prevalence of SHT was 13% and not correlated with proteinuria. Forelimb and hindlimb SAP were poorly correlated; therefore, trends in an individual animal should be monitored using the same measurement site. Additionally, values for Doppler SAP were determined in Shetland Sheepdogs.

Clinicopathologic and MRI Characteristics of Presumptive Hypertensive Encephalopathy in Two Cats and Two Dogs

Two dogs and two cats were evaluated for the acute-onset of abnormal mentation, recumbency, and blindness. All cases had systemic hypertension, ranging from 180 mm Hg to 260 mm Hg. MRI of the brain disclosed noncontrast-enhancing, ill-defined, T2-weighted (T2W) hyperintensities in the white matter of the cerebrum in the areas of the frontal, parietal, temporal, and occipital lobes. Lesions were also observed in the caudate nuclei and thalamus (n = 1 in each). Intracranial hemorrhage was observed in one animal. Diffusion-weighted imaging (DWI) was consistent with vasogenic edema in two animals. Retinal lesions were observed in three animals. Hypertension was secondary to renal disease in three animals. A primary underlying disorder was not identified in one animal. Normalization of blood pressure was achieved with amlodipine either alone or in combination with enalapril. In one cat, hypertension spontaneously resolved. In three cases, neurologic improvement occurred within 24–48 hr of normalization of blood pressure. The presumptive diagnosis of hypertensive encephalopathy was supported by the MRI findings and neurologic dysfunction coincident with systemic hypertension in which the neurologic dysfunction improved with treatment of hypertension. The prognosis appears good for the resolution of neurologic deficits with normalization of blood pressure in animals with hypertensive encephalopathy.

Biomarkers in the assessment of acute and chronic kidney diseases in the dog and cat

In both human and veterinary medicine, diagnosing and staging renal disease can be difficult. Measurement of glomerular filtration rate is considered the gold standard for assessing renal function but methods for its assessment can be technically challenging and impractical. The main parameters used to diagnose acute and chronic kidney disease include circulating creatinine and urea concentrations, and urine-specific gravity. However, these parameters can be insensitive. Therefore, there is a need for better methods to diagnose and monitor patients with renal disease. The use of renal biomarkers is increasing in human and veterinary medicine for the diagnosis and monitoring of acute and chronic kidney diseases. An ideal biomarker would identify site and severity of injury, and correlate with renal function, among other qualities. This article will review the advantages and limitations of renal biomarkers that have been used in dogs and cats, as well as some markers used in humans that may be adapted for veterinary use. In the future, measuring a combination of biomarkers will likely be a useful approach in the diagnosis of kidney disorders.

Big-endothelin 1 (big ET-1) and homocysteine in the serum of dogs with chronic kidney disease

This study was aimed at determining the serum concentration of homocysteine (Hcy) and big endothelin-1 (big ET-1, the precursor of endothelin) in dogs with chronic kidney disease (CKD) with and without hypertension, proteinuria and inflammation, in order to explore their role as biomarkers of hypertension associated with CKD. Hcy and big ET-1 were measured using an enzyme-linked immunosorbent assay and an enzymatic cyclic reaction, respectively, in dogs with CKD staged, as proposed by the International Renal Interest Society (IRIS), using serum creatinine, urinary protein to creatinine (UPC) ratio and systolic blood pressure, and classified as affected or not by inflammation based on the serum concentration of C-reactive protein (CRP). Serum Hcy was significantly higher in dogs of IRIS stages II, III and IV compared with controls and in proteinuric compared with non-proteinuric dogs. No differences relating to the degree of hypertension or to the CRP concentration were found. Serum big ET-1 significantly increased in dogs of IRIS stage IV compared with controls, in proteinuric compared with non-proteinuric dogs, in dogs with severe hypertension compared with those without hypertension, and in dogs with increased CRP compared to those with normal CRP concentrations. Hcy only correlated with serum creatinine but big ET-1 significantly correlated with serum creatinine, UPC ratio, systolic blood pressure, and increased CRP. In conclusion, both Hcy and big ET-1 increase in dogs with CKD. Although further research is needed, big ET-1, but not Hcy, may also be considered as a biomarker of hypertension.

Renal pathophysiology: lessons learned from the canine remnant kidney model

OBJECTIVE

To review the pathophysiology of chronic kidney disease (CKD) in dogs and the contributions of the canine remnant kidney model to our understanding of this disease.

DATA SOURCES

Original studies in the human and veterinary medical fields.

DATA SYNTHESIS

Three of the fundamental principles of modern nephrology-the intact nephron hypothesis, the trade-off hypothesis, and the hyperfiltration theory were developed directly as a result of studies of the remnant kidney model. Most of the pivotal early studies were conducted in dogs. As a result, our understanding of CKD, and of the renal and systemic adaptations to CKD, is largely based on studies of this model.

CONCLUSIONS

Studies of the remnant kidney model have advanced our understanding of the pathophysiology of CKD. Nearly every therapeutic intervention used in CKD, by veterinarians and physicians alike, has its basis in studies of the remnant kidney model or in knowledge that was derived from studies of this model. A great debt is owed to the canine participants in these studies and to a small number of key scientists who conducted this important and insightful research.

Arterial blood pressure, proteinuria, and renal histopathology in clinically healthy retired racing greyhounds

BACKGROUND

Physiologic peculiarities of Greyhounds as compared to other dogs make interpretation of laboratory results in this breed challenging for veterinarians. Hypertension in retired racing Greyhounds (RRG) can contribute to microalbuminuria (MA), overt proteinuria, and renal histologic lesions.

OBJECTIVES

To evaluate clinicopathologic findings, hemodynamic status, and renal histology in a population of healthy RRG.

ANIMALS

RRG presented to Ohio State University College of Veterinary Medicine for inclusion in a spay and neuter program.

METHODS

Cross-sectional study. RRG were classified as normotensive (<160 mmHg) or hypertensive (>160 mmHg) based on blood pressure (BP) determinations using Doppler and oscillometric methods. Of the dogs evaluated, 62% (n = 29) were hypertensive and 38% (n = 18) were normotensive. Health status was evaluated using routine clinicopathologic tests (CBC, serum biochemistry, urinalysis) as well as evaluation of fractional excretion of electrolytes and MA determinations. Adequate renal biopsy specimens (n = 15) were evaluated using light, immunofluoresence, and electron microscopy.

RESULTS

All serum biochemistry results were normal in 45/49 dogs, but MA was more common in hypertensive (84% positive for MA) as compared with normotensive (18% positive for MA) RRG. Observed renal lesions were mild and renal biopsy scores were low in this sample of RRG.

CONCLUSIONS

Hypertension is common in RRG and might be breed-related. It is associated with MA, but observed renal lesions are mild. Whether or not hypertension and MA in RRG leads to progressive renal damage requires longitudinal study.

Long-term follow-up of renal function in dogs after treatment for ACTH-dependent hyperadrenocorticism

BACKGROUND

Systemic hypertension and proteinuria are frequent complications in dogs with Cushing's syndrome and do not always resolve after treatment of hypercortisolism. Therefore, dogs with Cushing's syndrome may be at risk for renal dysfunction before and after treatment.

HYPOTHESIS/OBJECTIVES

To assess renal function in dogs with ACTH-dependent hyperadrenocorticism (ADHAC) before and after treatment.

ANIMALS

A total of 19 dogs with ADHAC and 12 control dogs.

METHODS

Renal function was assessed before and at 1, 3, 6, and 12 months after treatment. Twelve dogs were treated with trilostane and 7 dogs by transsphenoidal hypophysectomy. Routine renal markers were measured and urinary albumin (uALB), immunoglobulin G (uIgG), and retinol-binding protein (uRBP) were assessed by ELISA. Urinary N-acetyl-β-D-glucosaminidase (uNAG) was determined colorimetrically. All urinary markers were indexed to urinary creatinine concentration (c). Plasma clearance of creatinine (Cl(creat)), exo-iohexol (Cl(exo)), and endo-iohexol (Cl(endo)) was used to measure glomerular filtration rate (GFR). Data were analyzed using a general linear model.

RESULTS

Serum creatinine and urea concentrations increased post-treatment, but remained within reference ranges. Plasma Cl(creat) and Cl(endo) were significantly lower post-treatment, whereas Cl(exo) was not different. Urinary protein-to-creatinine ratio (UPC), uALB/c, uIgG/c, and uRBP/c were decreased post-treatment, but at 12 months 5/13 dogs remained proteinuric. Urinary NAG/c did not change significantly.

CONCLUSIONS AND CLINICAL IMPORTANCE

A decrease in GFR and persistent proteinuria post-treatment may warrant the clinician's attention. Future research including renal histopathology of dogs with persistent proteinuria or low GFR is needed to further assess renal outcome.

Echocardiographic and tissue Doppler imaging alterations associated with spontaneous canine systemic hypertension

BACKGROUND

Feline systemic arterial hypertension (SHT) is associated with a wide spectrum of left ventricular (LV) geometric patterns as well as diastolic, and to a lesser extent, systolic myocardial dysfunction. However, little is known about SHT-related cardiac changes in dogs.

HYPOTHESIS

SHT in dogs is responsible for morphological and functional cardiac alterations.

ANIMALS

Thirty dogs with spontaneous untreated SHT and 28 age- and body weight-matched healthy dogs as controls.

METHODS

Prospective observational study. Conventional echocardiography and 2-dimensional color tissue Doppler imaging were performed in SHT dogs by trained observers and compared with controls.

RESULTS

Forty-seven percent of SHT dogs (14/30) had diffuse concentric hypertrophy. None had left atrial dilatation and 10/30 (33%) had aortic insufficiency (AoI) associated with proximal aortic dilatation. Longitudinal diastolic left ventricular free wall (LVFW) motion was altered in all SHT dogs at the base (early to late diastolic wave ratio, E/A = 0.5 ± 0.1 versus 1.3 ± 0.3 for controls, P < .0001) and the apex (E/A = 1.6 ± 1.7 versus 3.9 ± 3.1, P < .05). Longitudinal motion of the interventricular septum at the base (E/A = 0.7 ± 0.4 versus 1.1 ± 0.1, P < .01) and radial LVFW motion in the subendocardium (E/A = 0.9 ± 0.5 versus 1.6 ± 0.3, P < .01) were also altered in dogs with SHT. Longitudinal LVFW systolic velocities and gradients were also significantly decreased (P < .05) in SHT dogs.

CONCLUSION AND CLINICAL IMPORTANCE

As in SHT in cats, SHT in dogs is associated with myocardial dysfunction independently of the presence of myocardial hypertrophy. However, unlike feline SHT, it results in a homogeneous LV geometric pattern with a relatively high prevalence of AoI.

Occurrence of systemic hypertension in dogs with acute kidney injury and treatment with amlodipine besylate

OBJECTIVES

To describe the occurrence of systemic hypertension in dogs with acute kidney injury and the efficacy of amlodipine besylate for its treatment.

METHODS

This retrospective study included 52 dogs with acute kidney injury (2007 to 2008) grouped based on the use of amlodipine in their treatment. Systemic blood pressure was measured with an oscillometric device at admission, before, during, and after amlodipine therapy.

RESULTS

Occurrence of systolic systemic hypertension (≥160 mmHg) and severe systolic systemic hypertension (≥180 mmHg) was 37% and 15% at admission and increased with hospitalisation to 81% and 62%, respectively. Twenty-two dogs were treated with amlodipine, at a median daily dosage of 0·38 mg/kg (interquartile range 0·28 to 0·49) divided in one to two applications per day. Amlodipine therapy was associated with a decrease in systolic systemic blood pressure of 24 mmHg (12 to 34) and a correction of severe systemic hypertension in 10 of 11 dogs within 24 hours. Overall, 73% of the dogs survived with a significantly lower proportion of survivors in treated compared to non-treated dogs (59% versus 83%, respectively, P=0·05).

CLINICAL SIGNIFICANCE

Results of this study reveal that systemic hypertension is common in canine acute kidney injury and that treatment with amlodipine is beneficial in reducing systemic hypertension. The potential effect of amlodipine on global outcome requires prospective assessment.

Ocular lesions associated with systemic hypertension in dogs: 65 cases (2005-2007)

OBJECTIVE

To characterize ocular findings in hypertensive dogs, determine prevalence of hypertension in dogs with ocular disease suggestive of hypertension, and examine possible relationships between degree of hypertension and ocular disease.

DESIGN

Retrospective case series.

ANIMALS

65 dogs initially referred for blood pressure measurement (n = 22), ophthalmic examination (25), or both (18).

PROCEDURES

Medical records were reviewed to identify dogs examined at the teaching hospital that underwent a complete ophthalmic examination and blood pressure measurement within a 24-hour period between January 1, 2005, and December 31, 2007. Signalment, history, blood pressure measurements, ophthalmic examination findings, and any vasoactive drug treatments were recorded. Ocular lesions considered likely to be associated with systemic hypertension included retinal hemorrhage, retinal detachment, hyphema, tortuous vessels, and subretinal edema.

RESULTS

Of the 65 dogs, 42 were hypertensive (systolic blood pressure ≥ 160 mm Hg) and 23 were normotensive. Sixty-two percent (26/42) of hypertensive dogs had ≥ 1 type of ocular lesion identified. Retinal hemorrhage was the most common ocular lesion in hypertensive dogs (17/42 [40%]). The presence of ≥ 1 type of ocular lesion had moderate sensitivity and specificity of 62% and 61 %, respectively, for identification of hypertension. Fifteen of the 25 (60%) dogs referred for blood pressure measurement after initial ophthalmic examination were found to be hypertensive.

CONCLUSIONS AND CLINICAL RELEVANCE

Ocular lesions are common in dogs with systemic hypertension. Dogs with hypertension or diseases associated with hypertension should be monitored carefully for evidence of ocular target organ damage, and hypertension should be systematically ruled out in dogs with characteristic ocular lesions.

Hypertension in small animal kidney disease

Kidney disease is commonly associated with hypertension in dogs, cats and other species. There are multiple mechanisms underlying the development of renal hypertension including sodium retention, activation of the renin-angiotensin system and sympathetic nerve stimulation. The relative importance of these and other mechanisms may vary both between species and according to the type of kidney disease that is present. Consideration of underlying disease mechanisms may aid in the rational choice of therapy in hypertensive patients.

Early Stage of Chronic Kidney Disease with Renal Injury Caused by Hypertension in a Dog

A 10-year-old spayed female Papillon weighing 4.0 kg presented with a history of persistent hematuria and pollakiuria. Concurrent bladder calculi, a mammary gland tumor, and nonazotemic early stage of chronic kidney disease with contracted kidneys were noted in this dog. The dog underwent cystectomy, unilateral mastectomy, and intraoperative renal biopsy. On the basis of histopathological analysis of renal biopsy results, it was suspected that renal injury of the dog was caused by persistent hypertension, and a follow-up examination revealed severe hypertension. The dog was treated with a combination of an angiotensin-converting enzyme inhibitor and calcium channel blocker. The treatment produced a good outcome in the dog, and there has been no progression of the chronic kidney disease for over 2 years.

Chronic kidney disease in small animals

Chronic kidney disease (CKD) affects multiple body systems and presents with a wide variety of clinical manifestations. Proper application of conservative medical management can profoundly affect the clinical course of CKD. Diagnosis and management is facilitated by staging CKD and applying therapies that are appropriate for the patient's stage of CKD. Therapy and follow-up of CKD are described, with emphasis on stage-based therapy to ameliorate clinical signs and slow progression.

An evidence-based review of therapies for canine chronic kidney disease

Successful treatment and prevention of kidney disease in dogs requires a multi-dimensional approach to identify and eliminate causes or exacerbating factors, provide professional evaluation on a regular basis and implement a comprehensive treatment programme when necessary. Over the years, many therapeutic and preventive interventions have been developed or advocated for chronic kidney disease in dogs, but evidence of efficacy or effectiveness is often lacking or highly variable. Accordingly, the main objective of this systematic review was to identify and critically appraise the evidence supporting various aspects of managing canine chronic kidney disease.