RESEARCHES REGARDING BLOOD PRESSURE
IN DOGS AND CATS
ABSTRACT
PART I. BIBLIOGRAPHIC SYNTHESIS
The bibliographic study comprises six chapters and is extended on 66 pages.
Chapter 1. Considerations regarding blood pressure in dogs and cats deals with the
factors determining blood pressure in arteries and with assessing means of blood pressure in
dogs and cats.
Chapter 2. Hypertension: definition, classification, epidemiology comprises the
definition of the forms of hypertension, its classification according to aetiology and data related
to hypertension incidence and prevalence in dogs and cats.
Chapter 3. Hemodynamic changes and mechanisms involved in the apparition of
hypertension deals with the relationship between cardiac flow and total vascular resistance, and
also the factors involved in the apparition of hypertension: neurogenic factors, vasodepressor
systems, kidney role in hypertension, the system renin-angiotensin-aldosterone, endothelial
dysfunction.
Chapter 4. Causes of hypertension in dogs and cats is related to the renal, cardiac and
endocrine-cause secondary hypertension.
Chapter 5. Consequences of hypertension presents the vascular changes and the
cardiac, ocular and renal complications of hypertension in dogs and cats.
Chapter 6. Diagnosis and treatment of hypertension in dogs and cats deals with the
diagnosis methodology, with the treatment opportunity and with the major classes of
medicines used in hypertension treatment in dogs and cats.
PART II. PERSONAL RESEARCHES
The personal researches comprises 13 chapters and is extended on 159 pages.
Chapter 7. Aim and general objectives of the study
The aim of the study was to enrich and deepen the knowledge regarding the variation
of arterial blood pressure, measured with non-invasive method, in healthy cats and dogs and
also for the animals on different pathological conditions.
The objectives were:
 to evaluate the accuracy and precision of blood pressure (BP) measurement with
the oscillometric method;
 to establish the reference BP values measured with the oscillometric method in
healthy cats and dogs;
 to evaluate and quantify the factors influencing BP during the process of
measurement;
 to establish, with a statistical method, the limits between the normal and the
pathological BP values (the limits cats and dogs may be considered hypotensive
or hypertensive from);
 to evaluate the differences between BP values according to breed, sex,
maintenance status;
 to assess the correlations between blood pressure and age, sex or maintenance
status;
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to evaluate blood pressure prevalence in chronic renal insufficiency, diabetes
mellitus and cardiac insufficiency;
to evaluate the relationship between the paraclinical changes and the blood
pressure level in different pathologic conditions
to evaluate the antihypertensive effect of some drugs belonging to the group of
inhibitors of the angiotensin-conversion enzyme and of the calcium-channel
blockers;
to evaluate the effect exerted by the medication for cardiac insufficiency on
blood pressure values.
Chapter 8. Evaluation of the oscillometric method for blood pressure measurement
This chapter evaluates the accuracy and precision of blood pressure measurements
with the oscillometric method, by comparing the results with simultaneous blood pressure
measurements with the direct method.
The researches were performed on 5 anaesthetized dogs, whose blood pressure was
simultaneously measured with the direct method and with the oscillometric method. In order
to measure the blood pressure directly, we established an arterial line through the femoral
artery catheterization; in order to supervise blood pressure, we used the invasive arterial
pressure line of the monitor Kontron Minimon 7138 B. The indirect blood pressure
measurement was performed with the oscillometric method with the help of the device
Cardell Veterinary Monitor 940. Blood pressure was successively measured at medial and
metatarsal arteries and at the medial caudal artery, and the results obtained were compared
with the BP values measured with the direct method.
The blood pressure measured with the oscillometric method at the thoracic member
(median artery), at the pelvic member (metatarsal artery) and at the tail base (median caudal
artery) was, on the whole, smaller than the one recorded with the direct method. In all the
three locations of blood pressure measurement assessed in this study, systolic blood pressure
(SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP) values obtained with
the oscillometric method had a mean error margin smaller with 5±7 mmHg than the ones
obtained with the reference method (the direct method) (table 8, table 10, table 11). This error
margin is acceptable, due to the fact that a difference of mean of 5±8 mmHg compared with
the reference method is allowed for the tensiometers used for humans.
Indifferently of the location of blood pressure measurement with the oscillometric
method, the correlation with the direct blood pressure determination was significant, very
good and direct proportional (r > 0.90, p < 0.01). However, BP measurement at the thoracic
member (median artery) and at the pelvic member (metatarsal artery) estimates SBP and MBP
values better than DBP value. On the contrary, at tail base (median caudal artery), the
oscillometric method estimated DBP value better than SBP and MBP values (table 9).
Consequently, blood pressure measured with the oscillometric method at the median,
metatarsal and median caudal arteries estimates the real blood pressure value well. Blood
pressure may be measured with the same accuracy at the median artery, metatarsal artery and
at the median caudal artery as well.
Chapter 9. Blood pressure measured with the oscillometric method in clinically
healthy cats
The researches were carried out at the Universitary Veterinary Clinics from
Timişoara, on 159 clinically healthy cats. Cats were 11 months-14 years old, the mean being
5.96 ± 3.48 years. The group was consisted of different-breed cats, and the proportion
between sexes was about 1:1, respectively 80 females and 79 males. Body weight was
comprised between 2 and 8 kg, with a mean of 4.48 ± 1.11 kg. Their maintenance status was
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assessed according to a clinical score, as follows: 1 - thin; 2 - underweight; 3 – fit body
condition; 4 – mildly overweight; 5 - obese.
Blood pressure was determined with the oscillometric method, with the help of the
device Cardell Veterinary Monitor 9401. The inflatable cuff was positioned around the
forelimb, between the elbow and carpus, at the level on the median artery. For each cat, a cuff
width of between 30-40% of the limb circumference was chosen. Blood pressure was
measured in the owner` s presence, after a period of acclimatization, before the physical
examination, to reduce the magnitude of ”white coat” hypertension. For each cat, the systemic
blood pressure value was calculated as the mean of five consecutive measurements.
The statistical processing of results allowed the establishment of the reference values
and of the variation blood pressure limits, measured with the oscillometric method, in
clinically healthy cats. So, SBP had a mean value of 124.7 ± 8.54 mmHg, and the mean DBP
and MBP values were 75.4 ± 10.08 mmHg, respectively 91.9 ± 8.45 mmHg (table 13). The
limits of blood pressure ranges in the clinically healthy cats, established by statistical method
(mean ± 1.282 standard deviations), were: 113.7 - 135.6 mmHg for SBP; 61.6 - 89.2 mmHg
for DBP; 81.1 - 102.7 in the case of MBP (table 14). Also, with the statistical method, we
established that SBP/DBP values that were bigger than 141/95 mmHg are strong suggestive
for hypertension, and SBP/DBP decrease below 107/55 mmHg indicates the tendency to
hypotension (table 15).
Blood pressure did not record significant differences between males and females, and
neither between the cat groups differentiated according to their maintenance status, assessed
by clinical score. We observed a slight, but significant correlation between age and blood
pressure, and the analysis of regression showed that SBP increased with 0.7 mmHg/year,
while DBP and MBP increased with 0.83 mmHg/year, respectively with 0.92 mmHg/year. On
the contrary, we did not observed any significant correlation between age and pulse frequency
(r = 0.13; p > 0.05). Blood pressure in the British Shorthair breed was significantly higher
than in the Persian, Birmanese, European or Siamese cats.
BP measurement after about 15 minutes of accommodation reduces significantly the
influence exerted by stress on blood pressure values. The differences between BP values
measured at tail base or forearm are not significant.
Chapter 10. Blood pressure in cats with chronic renal insufficiency.
The study was performed on 65 cats diagnosed with chronic renal insufficiency and
was consisted of blood pressure evaluation, of the establishment of hypertension prevalence
and of the evaluation of the risk factors associated with blood pressure increase in cats with
CRI appeared from natural causes. We took blood and urine samples from all cats, and
determined the biochemical parameters with specificity for renal function. Blood pressure was
determined in all cats with the oscillometric method, with the help of the electronic
oscillometer CARDELL Veterinary Monitor 9401, according to the previously described
standard procedure. Successive to the statistical processing of the data achieved, we observed
the following:
 blood pressure was significantly higher in the cats with chronic renal insufficiency
than in the healthy cats, the mean difference being of 25 mmHg.
 hypertension prevalence of the cats with chronic renal insufficiency in this group was
55%.
 hypertension was in a proportion of 92% a mixed one, while the isolated diastolic
hypertension was observed only in a proportion of 8%.
 hypertension was observed preponderantly in the cats with mild and moderate
azotemia, respectively in the stages 2 and 3 of the chronic renal insufficiency.
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 blood pressure in the cats with chronic renal insufficiency was not correlated
significantly with age, and the age did not record significant differences between the
normotensive and the hypertensive cats.
 there was a significant inversely proportional correlation between blood pressure and
plasmatic potassium concentration.
 we did not observe any significant correlations between the plasmatic creatinine, urea
and sodium concentrations and the blood pressure value.
 proteinuria, assessed according to the urine protein to creatinine ratio, was
significantly higher in the hypertensive cats than in the normotensive ones.
Chapter 11. Amlodipine effect in hypertension control in cats with chronic renal
insufficiency
The researches were performed on 11 cats, 7-14 years old, diagnosed with
hypertension secondary to the chronic renal insufficiency, and attempted to evaluate
amlodipine effect on blood pressure and renal function in cats with naturally-appeared chronic
renal insufficiency.
Blood pressure was determined with the oscillometric method, with the help of the
device Cardell Veterinary Monitor 9401, according to the standard procedure. All cats
included in this study had a plasmatic creatinine concentration over 1.9 mg/dl and could be
distributed in the stages 2 and 3 of the chronic renal insufficiency. We took blood and urine
samples from all cats to determine the biochemical parameters with specificity for renal
function. Amlodipine was administrated once day in a dose of 0.625 mg/day (0.1 – 0.2
mg/kg). In order to supervise treatment efficacy, blood pressure was taken before and after 7,
30, respectively 120 days of treatment. Also to assess amlodipine influence on renal function,
the blood and urine samples were taken and analyzed before and after 30 and 120 days of
treatment.
The statistical result processing showed that amlodipine determines a gradual and
significant blood pressure reduction in the cats with chronic renal insufficiency. So, under the
amlodipine treatment, blood pressure decreased with a mean value of 15 mmHg after 7 days,
respectively with 25 mmHg after 30 days and with 31 mmHg after 120 days of treatment
(table 31). However, amlodipine did not influence significantly the blood biochemical
parameters of the renal profile, so it did not influenced negatively the renal function during
treatment. Moreover, under the amlodipine treatment, proteinuria assessed in concordance with
the urine protein to creatinine ratio decreased almost to the significance limit of 95%.
Consequently, the amlodipine treatment, by reducing blood pressure and proteinuria,
could reduce the chronic renal insufficiency rate of progression to the end uremic stage.
Chapter 12. Benazepril effect on blood pressure and renal function in cats with
chronic renal insufficiency
The study was carried out on 12 cats, 4-16 years old, diagnosed with chronic renal
insufficiency, at the Universitary Veterinary Clinics from Timişoara. Benazepril was
administrated orally in a dose of 0.25 mg/kg in the first week; after that, the dose was
increased to 0.5 mg/kg once a day, until the end of the study. In order to supervise treatment
efficacy, blood pressure was measured before and after 7, 30, respectively 120 days of
treatment. Also, in order to assess the influence exerted by benazepril on renal function, we
took blood and urine samples before and after 30 and 120 days of treatment. Blood pressure
was determined with the oscillometric method, at the thoracic member, in the presence of
cat’s owner, after a 15-minute accommodation. For each cat, a cuff width of between 30-40%
of the measurement site was chosen and the systemic blood pressure value was calculated as
the mean of five readings, with interval of 20 to 30 seconds between consecutive readings.
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The differences between SBP, DBP and MBP measured before and after the first week
of treatment were statistically insignificant (p>0.05). On the contrary, at 4 and 12 weeks,
SBP, DBP and MBP were significantly lower (p<0.05) than the ones recorded before the
benazepril treatment. Blood pressure reduction under the benazepril treatment in the cats with
chronic renal insufficiency was of low amplitude (the mean blood pressure decreased with
approximately 15 mmHg). Consequently, benazepril may be used in the treatment of renal
hypertension when the risk level for the apparition of hypertensive lesions in the target organs
is reduced or moderate.
The treatment with benazepril did not cause the aggravation of the renal dysfunction
assessed according to the changes of the sanguine biochemical parameters. The plasmatic
creatinine determined at 4 and 12 weeks after the beginning of the benazepril treatment was
lower with 10.1%, respectively 14%, but the differences were not statistically significant
(p>0.05). The plasmatic potassium concentration increased with a mean value of 9.2 % after 4
weeks and with 11.4% after 12 weeks of treatment, but the differences to the initial mean
value were insignificant (p>0.05), and the mean values belonged to the normal physiological
variation. The benazepril treatment determined the significant proteinuria reduction, assessed
according to the urine protein to creatinine ratio, after 30 days of administration. Moreover,
blood pressure reduction under the benazepril treatment was positively and significantly
correlated with the value of the urine protein to creatinine ratio. As a result, benazepril
administration, by reducing proteinuria and blood pressure, may lead to the decrease of
chronic renal insufficiency rate of progression in cats and to prolong cats’ life.
Chapter 13. Blood pressure measured with the oscillometric method in clinically
healthy dogs
The researches were carried out on 237 clinically healthy dogs, with age between 6
months and 16 years. Blood pressure was measured with the oscillometric method, with the
help of the device Cardell Veterinary Monitor 9401. In all dogs, the determinations were
performed at the thoracic member, at median artery level, using cuffs with a width of about
35-40% of the forearm circumference. Blood pressure measurement was performed in the
presence of dog’s owner, after a 10-15 minute accommodation with the area and with the
measurement equipment. For each dog, the systemic blood pressure value was calculated as
the mean of five readings, with interval of 15 to 30 seconds between consecutive
measurements.
The statistical result processing led to the establishment of the reference values and of
the variation limits of blood pressure measured with the oscillometric method in clinically
healthy dogs (table 38). So, SBP recorded a mean value of 126.4 ± 11.24 mmHg, and the
mean DBP and MBP values were 74.6 ± 10.48 mmHg, respectively 91.8 ± 9.71 mmHg (table
38). The blood pressure variation limits in clinically healthy dogs, established with the
statistical method (mean ± 1.282 standard deviations), were: 112 – 140.7 mmHg for SBP;
61.3 – 87.9 mmHg for DBP; 79.3 – 104.2 in the case of MBP (table 39). Also with the
statistical method, we established that the SBP/DBP values bigger than 141/95 mmHg define
hypertension, and the hypotension may be considered from SBP/DBP values that are smaller
than 104/53 mmHg (table 40).
The blood pressure value did not record significant differences between males and
females and neither according to the place of measurement. We observed a slight, but
significant correlation between age and blood pressure, and the regression line equation made
evident that SBP increases with 1.1mmHg/year, and DBP and MBP increase with 0.8
mmHg/year, respectively with 1.0 mmHg/year. Taking into consideration the mean life
duration of the canine species, we may conclude that age is not a variable that can explain
blood pressure increase up to hypertension. In clinically healthy dogs, blood pressure is a
variable that depends more on breed and less on age. So, the blood pressure value in the
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German Shepherd breed was significantly higher than in the entire group of clinically healthy
dogs. In the Golden Retriever breed, blood pressure was significantly smaller than the mean
BP value recorded in the entire group of clinically healthy dogs. The differences regarding
SBP, DBP and MBP values between the breeds Labrador, Husky, Poodle and West Highland
White Terrier were not significant.
In clinically healthy dogs, blood pressure is a variable depending more on breed and
less on age.
Chapter 14. Blood pressure in dogs with chronic renal insufficiency
This study attempted to assess hypertension prevalence in the dogs with chronic renal
insufficiency and the correlations between renal profile biochemical parameters and blood
pressure level.
The researches were performed on 54 dogs, with age between 2.5 and 16 years,
diagnosed with chronic renal insufficiency at the Universitary Veterinary Clinics from
Timişoara. Blood pressure was determined with the oscillometric method, according to the
previously described procedure. We took blood and urine samples from all dogs studied. On
blood, we determined the following parameters: creatinine, urea, phosphatemia, potassium
and sodium. On urine, we estimated the quantitative proteinuria by determining the urine
protein to creatinine ratio.
The mean BP values determined in the dogs with CRI were higher than the ones
recorded in the healthy dogs, and the differences were statistically significant for SBP and for
DBP or MBP as well (table 45). In the case of SBP, the mean difference was 23.9 mmHg,
and in 95% of the cases the differences were between 15.9 – 31.9 mmHg. Similarly, DBP and
MBP were higher with 23 mmHg in the dogs with CRI, and 95% of the differences were
between 16 and 30 mmHg. Hypertension, for the dogs in this study, was defined as SBP>149
mmHg, and/or DBP>95 mmHg. Considering these limits, the global hypertension prevalence
was of 59%. We remarked that 55% of the dogs had a mixed hypertension (systolic and
diastolic), and only 4% presented isolated diastolic hypertension; isolated systolic hypertension
was not identified in any case (fig. 67).
On the whole, blood pressure recorded higher values in the dogs in stage 2 compared
to the ones in stages 3 and 4 of CRI (fig. 68 and fig. 69), and the differences between the
mean values were significant for SBP, and also for DBP or MBP (table 47). On the contrary,
pulse frequency did not record significant differences according to CRI evolution stage.
About 71% of the hypertensive dogs in this study were in the stages 2 and 3 of CRI and only
24 % in the stage 4 (fig. 70). We remarked that, in an important proportion, hypertension was
observed in the initial CRI stages, when the clinical signs of the renal affection are usually
little expressed. The clinical importance of this aspect is consisted of the fact that BP
measurement and hypertension detection may be revealers in CRI diagnosis in the early
stages, even in the preazotemic ones.
In the dogs with chronic renal insufficiency in this study, there were not significant
correlations between blood pressure value and the seric concentrations of creatinine, urea,
phosphorus, total protein, albumin, sodium and potassium. Also, between the dogs with CRI
grouped as normotensive and hypertensive, we did not observe significant differences
regarding the investigated sanguine biochemical parameters. On the contrary, the urine
protein to creatinine ratio was significantly higher in the hypertensive dogs than in the
normotensive ones. Moreover, we recorded a good positive and significant correlation
between the value of the urine protein to creatinine ratio and SBP, respectively MBP,
meaning that proteinuria increases in a relation of direct proportionality with the blood
pressure level in the dogs with CRI (fig. 72, fig. 73).
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Chapter 15. Effect of enalapril administration on blood pressure and renal
function in dogs with chronic renal insufficiency
The objective of this study was to evaluate the efficacy of chronic enalapril
administration in the blood pressure control in dogs with naturally-appeared CRI.
Circumstantially, we supervised the effect of this medicine on the renal function assessed
according to the sanguine biochemical parameters and to the urine protein to creatinine ratio.
The researches were performed on 13 dogs, with age between 2.5 and 14 years,
diagnosed with chronic renal insufficiency at the Universitary Veterinary Clinics from
Timişoara.
Enalapril was administrated in a dosage of 0.25 mg/kg in the first week and 0.5 mg/kg
in the second week. Blood pressure was measured before and after 7, 30, respectively 90 days
of treatment. The blood and urine samples were taken and analyzed before and after 30,
respectively 90 days of treatment.
The enalapril treatment led to the progressive reduction, of little amplitude, of the
blood pressure in dogs with chronic renal insufficiency. So, at the evaluation performed in the
30th day of treatment, we observed that SBP, DBP and MBP decreased with a mean value of
about 10 mmHg, and after three months of treatment SBP was reduced with about 12 mmHg,
and DBP and MBP with a mean of 15 mmHg, respectively 14 mmHg. Consequently, enalapril
may be used in the treatment of 1- and 2-stage hypertension, secondary to chronic renal
insufficiency, being able to reduce blood pressure below the target values of 150/95 mmHg.
The enalapril treatment did not influence negatively the sanguine biochemical
parameters of the renal profile during the treatment and did not accelerate the chronic renal
insufficiency evolution in the dogs in this study. However, enalapril administration generated
the significant proteinuria reduction, assessed according to the urine protein to creatinine
ratio. So that the enalapril, due to its antiproteinuric and antihypertensive effect, may
represent an efficient means of renal protection, which can decrease CRI progression rate.
Chapter 16. Blood pressure in dogs with diabetes mellitus
The study was carried out on 33 dogs, with age between 1.5 and 12 years, diagnosed
with diabetes mellitus at the Universitary Veterinary Clinics from Timişoara. Systolic,
diastolic and mean blood pressure and pulse frequency were determined with the
oscillometric method. At the moment of study, we took blood and urine samples from all
dogs, and determined the common biochemical parameters. In a group including 11 dogs with
blood pressure higher than 150/95 mmHg at two successive measurement, we introduced an
antihypertensive treatment with ramipril, administrated in a dosage of 0.125 mg/kg, once a
day, for a week; after that, the dose was increased to 0.25 mg/kg, once a day, in the case of 6
of the dogs. The assessment of the hypertensive effect was performed by measuring BP before
and after approximately 7, 30 (30±7 days), respectively 90 (90±20) days.
In the dogs with diabetes mellitus, mean BP values were bigger than the ones
measured with the same method in clinically healthy dogs (fig. 83), and the differences were
significant regarding SBP, and also regarding DBP, respectively MBP (table 55).
Hypertension prevalence was 42.4% (fig. 84). All dogs with systolic hypertension had
diastolic blood pressure higher than 95 mmHg. Also, we did not observe any dog with
isolated systolic or diastolic hypertension.
The relationship between blood pressure and the biochemical parameters determined
in the dogs with hyperglycemia was assessed with the correlation test Pearson. The results of
this test show that there were not significant correlations between SBP, DBP or MBP values
and the seric concentrations of sanguine biochemical parameters (tabelul 56). Moreover, the
comparison of the mean sanguine biochemical parameters between the normotensive and
hypertensive dogs with hyperglycemia did not show significant differences (table 57). Also,
we did not observe a significant correlation between BP values and the urine protein to
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creatinine ratio, although the mean value of this proportion was higher in the hypertensive
dogs with diabetes mellitus than in the normotensive ones, but the difference was not
significant (p>0.05).
Hypertension treatment with ramipril led to blood pressure reduction to the level
where the risk of apparition of hypertensive lesions in the target organs is neglectable or, at
most, reduced. Ramipril administration in dogs with diabetes mellitus did not influence
significantly the sanguine biochemical parameters of the renal profile, but it reduced the urine
protein to creatinine in the hypertensive dogs with diabetes mellitus. The ramipril, with its
hypotensive and antiproteinuric effect, could be used as an efficient means of renal protection
in hypertensive dogs with diabetes mellitus.
Chapter 17. Blood pressure in dogs with cardiac insufficiency
The study was performed on 61 different-breed dogs, 33 males and 28 females,
diagnosed with cardiac insufficiency at the the Universitary Veterinary Clinics from
Timişoara.
The systolic, diastolic and mean blood pressure and pulse frequency were determined
with the oscillometric method, with the help of the device Cardell Veterinary Monitor 9401,
according to the previously mentioned standard procedure. Blood pressure was supervised in
dynamics in a subgroup consisted of 11 dogs with mitral insufficiency and consecutive cardiac
insufficiency in stages 1 (n=1), 2 (n=5) and 3 (n=5). All dogs in this subgroup were treated
with benazepril, administrated in a dosage of 0.25 mg/kg in the first week; after that, we
increased the dose to 0.5 mg/kg once a day, and blood pressure was measured after 10 and 45
days of treatment. In the dogs with cardiac insufficiency, the mean BP values were bigger
than the ones measured with the same method in clinically healthy dogs (fig. 91), and the
differences were insignificant for SBP and significant for DBP or MBP (table 61). However,
we observed that the mean values and also 95% of the individual values did not overtake the
limits of BP physiological variation and neither the limit between normotension and
hypertension, calculated with the statistical method in the study performed on clinically
healthy dogs (SBP/DBP >149/95 mmHg).
The differences between the mean BP values recorded in stages 1 and 2 were
insignificant. On the contrary, BP in the dogs with cardiac insufficiency in stage 1 was
significantly higher than the one measured in the dogs in stages 3 and 4 of cardiac
insufficiency (table 62). The benazepril treatment led to a more accelerated reduction of DBP
and MBP than of SBP. After 10 days of treatment, SBP, DBP and MBP recorded values that
were lower with 6 - 7 mmHg, but the differences were not significant (fig. 93). After the
increase of the benazepril dosage to 0.5 mg/kg/day, at the measurement performed after 45
days of treatment, we observed that SBP decreased with 7 mmHg, but the difference was not
statistically significant (p=0.34), and neither clinically. On the contrary, DBP and MBP
decreased with a mean of 10 mmHg, and the differences were statistically significant and
could be considered as having significant clinical importance (table 63).
The administration of benazepril did not influence significantly the renal profile
biochemical parameters (table 64).
Chapter 18. Histopathological aspects in dogs with hypertension secondary to
chronic renal insufficiency
The tissue samples were taken from two dogs with renal insufficiency and
hypertension who died of natural causes. We took fragments of renal tissue, myocardium and
vascular walls. After sample processing and staining with the trichromic method, we could
draw the following conclusions:
 in kidneys, beside the lesions specific to chronic renal insufficiency, we observed
diffuse hyalinosis of the arteriolar wall and the thickening of the arteriole media
associated with focal hyalinosis, lesions that can be attributed to hypertension.
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in the arterial walls, we identified lesions secondary hypertensive injury,
respectively diffuse hyalinosis, vascular sclerosis and diffuse media calcification.
General conclusions
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There is a very good, direct proportional correlation between the blood pressure values
measured with oscillometry and with the direct method.
The blood pressure measured with the oscillometric method at median artery,
metatarsal artery or at median caudal artery estimates well the real blood pressure
value.
The systolic blood pressure and the mean blood pressure were estimated better at
forearm and metatarsus than at tail base, while the diastolic blood pressure was better
estimated at tail base.
The blood pressure measured with the oscillometric method in clinically healthy cats
recorded mean values of 124.7 ± 8.54 mmHg for the systolic blood pressure, 75.4 ±
10.08 mmHg for the diastolic blood pressure, respectively 91.9 ± 8.45 mmHg for the
mean blood pressure.
The variation limits of the blood pressure measured with the oscillometric method in
clinically healthy cats are comprised between 113.7 – 135.6 mmHg for the systolic
blood pressure, 61.6 – 89.2 mmHg for the diastolic blood pressure and 81.1 – 102.7 in
the case of the mean blood pressure.
In cats, hypertension may be defined as a systolic blood pressure that is higher than
142 mmHg and/ or diastolic blood pressure higher than 96 mmHg, while the systolic
and/ or diastolic blood pressure values smaller than 107 mmHg, respectively 55
mmHg indicate the tendency to hypotension.
Blood pressure does not record significant differences between males and females and
neither according to the maintenance status, assessed with a body condition score, in
the clinically healthy cats.
In conscious cats, blood pressure measurement may be carried out with approximately
the same accuracy at tail base and at forearm.
Blood pressure measurement after an about 15-minute accommodation reduces
significantly the influence exerted by stress on blood pressure values.
In healthy cats, there is a slight, but significant correlation between age and blood
pressure, but the age does not represent a variable determining the increase of blood
pressure until hypertension.
Blood pressure values in healthy cats may record significant differences between
breeds.
Blood pressure in cats with chronic renal insufficiency is higher than in clinically
healthy cats, the mean difference of 25 mmHg being statistically and clinically a
significant one.
In cats with chronic renal insufficiency, hypertension was preponderantly met in the
mixed form (in a proportion of 90%), and the global hypertension prevalence was of
55%.
Hypertension was preponderantly met in cats with mild and moderate azotemia,
respectively in stages 2 and 3 of chronic renal insufficiency.
In cats with chronic renal insufficiency, there is a significant inverse proportional
correlation between blood pressure value and plasmatic potassium concentration, and
we did not observe any significant relationship between the plasmatic creatinine, urea
and sodium concentrations and the blood pressure value.
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 Hypertension may cause proteinuria advance in cats with chronic renal insufficiency.
 The treatment with amlodipine controls efficiently and safety the renal-cause
hypertension in cats.
 Amlodipine administration led to a mean blood pressure reduction with 30 mmHg,
justifying the recommendation of amlodipine in the treatment of hypertension with
severe and moderate risk of affection in the target organs.
 Amlodipine did not influence significantly the sanguine biochemical parameters of the
renal profile, so that they do not influence significantly the renal function in cats with
chronic renal insufficiency.
 The treatment with amlodipine led to proteinuria reduction, assessed through the value
of the proportion protein/urinary creatinine.
 Benazepril administration in a dosage of 0.5 mg/kg, once a day, led to a significant
blood pressure reduction, but of small amplitude (the mean blood pressure decreased
with about 15 mmHg), in cats with chronic renal insufficiency.
 Benazepril may be used in the treatment of renal-cause hypertension when the risk
level for the apparition of hypertensive lesions in the target organs is a reduced or
moderate one.
 The administration of benazepril in dosage of 0.5 mg/kg is safety and without adverse
effects in cats in the first chronic renal insufficiency stages.
 The treatment with benazepril in cats with chronic renal insufficiency did not lead to
renal function aggravation and determined the significant reduction of proteinuria
assessed through the value of the urine protein to creatinine ratio.
 Because it causes proteinuria and blood pressure reduction, the treatment with
benazepril may decrease the chronic renal insufficiency progression rate in cats and
may prolong cats’ life.
 In clinically healthy dogs, the systolic blood pressure recorded a mean value of 126.4
± 11.24 mmHg, and the mean diastolic blood pressure and mean blood pressure values
were 74.6 ± 10.48 mmHg, respectively 91.8 ± 9.71 mmHg.
 The variation blood pressure limits in clinically healthy dogs are comprised between
112 – 141 mmHg for the systolic blood pressure and between 61 – 88 mmHg for the
diastolic blood pressure.
 Hypertension in dogs may be defined as the systolic and/or diastolic blood pressure
higher than 149 mmHg, respectively 95 mmHg, and hypotension may be taken into
consideration from the systolic and/or diastolic blood pressure values smaller than
104, respectively 53 mmHg.
 Blood pressure value does not record significant values between males and females
and neither according to the place of measurement (forearm, tail base, and metatarsus).
 In clinically healthy dogs, blood pressure is a variable that depends more on breed and
less on age.
 Age is not a variable able to lead to blood pressure increase up to hypertension.
 Blood pressure in dogs with chronic renal insufficiency is significantly higher than the
one recorded in clinically healthy dogs.
 In dogs with chronic renal insufficiency, hypertension may be met in over 50% of the
cases, and the proportion of hypertensive dogs is bigger in the first stages of this disease.
 Blood pressure measurement and hypertension detection may be revealers in the
diagnosis of chronic renal insufficiency in its early stages, when the clinical expressions
are not evident at all.
 Hypertension leads to proteinuria increase, fact that may intensify the chronic renal
insufficiency evolution to the final, uremic stage.
XXIII
 The treatment with enalapril leads to the progressive blood pressure reduction, but of
small amplitude, in dogs with chronic renal insufficiency.
 Enalapril may be used in the treatment of 1 and 2-stage hypertension, secondary to the
chronic renal insufficiency, being able to lead to blood pressure reduction below the
target values of 150/95 mmHg.
 The treatment with enalapril did not influence negatively the sanguine biochemical
parameters of the renal profile during treatment and did not accelerate the chronic
renal insufficiency evolution in dogs.
 Enalapril administration led to the significant reduction of proteinuria, assessed
according to the urine protein to creatinine ratio.
 Due to its antiproteinuric and antihypertensive effect, the treatment with enalapril may
lead to the reduction of chronic renal insufficiency progression rate in dogs.
 Blood pressure in dogs with diabetes mellitus records mean values that are
significantly higher than the ones observed in clinically healthy dogs.
 Hypertension in dogs with diabetes mellitus was preponderantly met in its mixed
form, and the prevalence was 42%.
 Proteinuria, assessed according to the urine protein to creatinine ratio, was higher in
the hypertensive dogs with diabetes mellitus than in the normotensive dogs, but the
mean value was between the physiological limits in both cases.
 The treatment of hypertension with ramipril may lead to blood pressure reduction to
levels where the risk of apparition of hypertensive lesions in the target organs is
minimal or mild.
 The treatment with ramipril could be used as efficient means of renal protection in
hypertensive dogs with diabetes mellitus.
 Blood pressure in dogs with cardiac insufficiency was, in a proportion of 95%,
between normal limits for the canine species.
 In the first cardiac insufficiency stage, blood pressure is significantly higher than in
the final stages, the apparition of hypertension being possible as well.
 The treatment with benazepril, administrated in dosage of 0.25 mg/kg – 0.5 mg/kg,
once a day, leads to a significant blood pressure reduction, of small amplitude.
 In the renal-cause hypertension, in kidneys, beside the lesions that are characteristic to
chronic renal insufficiency, we observed diffuse hyalinosis of the arteriolar wall and
the thickening of arteriola media, associated with focal hyalinosis.
 In the arterial walls, we identified lesions secondary to the hypertensive injury,
respectively diffuse hyalinosis, vascular sclerosis and media diffuse calcification.
XXIV