marți, 12 martie 2013

ARTERIAL HYPERTENSION IN DOGS


The 19 th Annual ECVIM Congress
Porto, Portugal, September, 8 – 10, 2009.





Researches   on   the  arterial hypertension  
 incidence in dogs

Brăslaşu M.C., Brăslaşu Daniela Elena, Joiţa Silvia,  Tudor Poliana

Faculty of Veterinary Medicine, Bucharest, Romania




Clinical studies were realized during a  4 month period. 1618 female and male dogs from different breeds have been examined (47,71% males and 52,28% females). The examination included: clinical examination, electrocardiography, echocardiography and blood pressure evaluation.
Diagnosis of arterial hypertension was established using the oscilometric method (VET HDO monitor – S+B medVET). Dogs were placed in lateral recumbency and the determinations were made either on the fore leg, or on the tail. Blood pressure determination was scheduled at the end of the clinical examination, when the animals were quiet. 5 determinations were made for each patient, and the arithmetical mean was calculated for the values obtained (systolic, diastolic and medium blood pressure, pulse). Blood pressure wasn’t evaluated in excited animals. Dogs with high values of arterial blood pressure obtained at the first determinations, but with normal physiological values in the last determinations, weren’t included. Although mean values of arterial blood pressure specified by Vet Direct Services – the producing company -  are 135 mmHg (Systolic pressure)  and 75 mmHg (Diastolic pressure), we diagnosed high blood pressure when values obtained were above 150 mmHg (Systolic pressure) şi 90 mmHg(diastolic pressure).
167 dogs (10.32% from the entire group examined) were diagnosed with high blood pressure. 52.69% were females and 47.30% males. We considered that a sex propensity can not be incriminated.
High blood pressure was diagnosed in the following breeds of dogs: Mixed dog (medium breed) – 20.35%; German Shepard – 17.96%; Cocker spaniel – 13.17%; Boxer – 7.78%; Rottweiler – 6.58%; Caniche – 5.98%; German Brack – 5.38%;   Setter – 3.59%;  Pekinese – 2.99%; Foxterrier – 2.39%; Labrador Retriever 1.79%; Collie 1.79%;  Doberman – 1.79%; Great Dane, Amstaff, Dalmaţian, Romanian Shepard, Airedale terrier, Schnautzer, Teckel, Caucazian, Aikito and Pitbull – 0.59 – 1.19% (for each breed).
Regarding blood pressure values, 16.76% from all patients had systolic blood pressure above 200 mmHg and 33.53% diastolic blood pressure over 115 mmHg.
The age of high blood pressure animals was 10.45±0.22 years (10 years and 4 month ± 2 month) (SD = 2.89). From the total number of animals with high blood pressure, 18 were Rottweilers, Schnautzers, Great Danes, Romanian Shepard, Caucasians and Aikito. In these breeds, the age was 8.47±0.67 years (SD – 2.88).
Conclusively, in our study,  the incidence of  high blood pressure in dogs was 10.32%. The age on animals diagnosed with high blood pressure was 10.45±0.22 years. No propensity related to breed or sex couldn’t be incriminated in this condition.

Material   and   Method

The research was conducted in the Internal Medicine Department of the Faculty of Veterinary Medicine Bucharest during 5 months period: 1st Nov 2008 – 31 st March 2009.
1618 dogs from different breeds and  ages were examined from the cardiovascular point of view.
Animals have been subjects of medical check-ups for the  following reasons:
1.      Cardiovascular diseases
2.      Systemic diseases along with cardiac signs: vascular ectasia, cavity effusions, ophthalmologic signs et al.
3.      Old animals, which were supported to undergo surgical procedures.

Medical check/up consisted in:
A.              General examination: anamnesis, inspection, palpation, auscultation, thermometry.
B.           Special exams: ECG, thoracic Rx, echocardiography, arterial blood pressure determination, hematological and biochemistry evaluations.

Routine check-up included a general examination end electrocardiography. Animals with signs of cardiovascular disease (dispnoea, tiredness, coughing, valvular murmur, cardiac rhythm changes, lethargy) were checked using echocardiography, thoracic Rx, arterial blood pressure determination and biochemistry evaluation.
In animals with epistaxis, limbs oedema, ocular signs, lethargy, movement bad coordination or neurological symptoms with sudden beginning, arterial blood pressure was checked constantly.
Arterial blood pressure determination.
a) Device.
- determination of arterial blood pressure was done by oscillometric method using 2 device: Memo Diagnostic MDPRO Cat and Dog Blood Pressure (HDO) (used in most of cases) and OMRON R-1 (for human use).
- systolic, diastolic and mean arterial blood pressure was checked (Mean Arterial blood pressure - only with Memo Diagnostic) and pulse frequency.
b) Arterial blood pressure determination in dogs
- only awake animals have been checked
- dogs have been checked in lateral or sterno-abdominal recumbency. The recumbence was smoothly imposed by the owner.
- in the rare situations when the dog refused the recumbency or was afraid of adopting this position, blood pressure was determined in standing position with the cuff of the device at the bottom of the tail.
- blood pressure determination was done at the end of clinical examination, when the animal has already got used with the environment, with the doctor and with the examination technique.
- blood pressure was not determined in nervous dogs.
c) Data interpretation
- on average of 5 determinations have been made for each animal. When big differences were observed between values, 3-5 more determination were performed.
- the average of the values has been calculated. In case a value was too high, usually during the first 2 determinations, high or too low, it was not considered.
- value correction has been done depending on the place of blood pressure determination toward the heart base (in recumbency, systolic adjustment if not standing, 1 mm Hg decrease per 1 cm lower than heart level).
- although normal  values of blood  pressure can vary between 118 ± 17 and 149 ± 20 mm Hg (Labrador – Greyhound)(Angela Bodey – Waltham Focus, 1997) we consider as hypertensive the animals with values higher than 150 mm Hg PAS and 90 mm Hg PAD.
- animal with high blood pressure values but with a normal clinical status (clinically healthy) have been double checked after 5 – 7 days. If blood pressure values were normal, the subjects haven’t been considered as hypertensive.
High values of blood pressure in  nervous dogs without specific clinical signs were considered a consequence of nervousness.



Results   and   Debates


From the total number of animals examined (cardiovascular system), 167 dogs (10.32%) have been diagnosed with arterial hypertension (figure 1).


Incidence of high blood pressure in dogs
(number animals)


            We consider that the prevalence of arterial hypertension in the studied population is normal, the value being included in the limits described by other authors (Bodey şi Michell, 1996; Remillard, Ross şi Edy, 1991, Stepien şi Henik, 2009).  We emphasize the fact that this 10.32% includes also the renal hypertension.
            We consider the animals that had values higher than 150mmHg – TAS and 90 mm HG TAD as having HTA. We had some exceptions:
-         We didn’t consider high values in excited animals as pathological, these animals being not included in this group. In the situations where some clinical symptoms suggested HTA (epistaxis, polyuria - polydipsia, oedema etc), the animals have been re-examined at a 5 – 7 days interval. Some of these dogs have been examined at home by the owner (arterial blood pressure determinations with devices based on oscilometric principle and with muffs adequate to the breed).
-         When animals had high values of arterial pressure, but the clinical signs suggesting a cardiovascular or a systemic disease were absent (clinical evaluations, blood biochemistry determinations), they were included in the batch considered in the study only if: 1. Values were over 180 – 190 mm Hg – TAS and 2. High values persisted at the following determinations.
In all situations a positive relationship was observed between high values of PAS and PAD. In 19 situations, PAD had normal values and PAS was out of range - 155 – 200 mm Hg. These 19 animals were diagnosed with systolic arterial blood pressure.
PAS values in animals considered as being hypertensive was 182.015 ± 1.53 mm Hg (Standard Deviation = 19.85).
Average value of arterial blood pressure was 135.00 ± 1.31 mm Hg (Standard deviation = 15.98).
PAD values in animal was 113.53 ± 1.18 mm Hg (D.S. = 14.28).
Repartition of animals on groups depending on the arterial blood pressure (10 mm Hg) is presented in figures 2 – 4.


Repartition of animals on blood pressure values- PAS groups
(no. animals/mm Hg)


Repartition of animals on blood pressure values- PAM groups
(no. animals/mm Hg)


Repartition of animals on blood pressure values - PAD groups
(no. animals/mm Hg)

Regarding the incidence according to the sex, 88 (52.69%) were females and 79 (47.30%) were males. These results would indicate a female predisposition to HTA, but we consider this is not relevant for the following reasons:   
1.            Repartition of the animals according to the sex criteria was of 52.28% females şi 47.71 % males. There is a direct relationship between the number of animals/sex in the study and the animals with HTA
2.            There is an explanation for the higher number of females in the batch: the majority of females that had to undergo a surgical procedure in the Obstetrical Department had previously a cardiovascular control.
We consider there is no sex predisposition on high blood pressure. Bodey A.R. şi Michell A.R. have pointed out in 1996 a higher predisposition of males to develop high blood pressure.

Animals diagnosed with high blood pressure were aged 1.8 – 17 years, with an average 10.45 ± 0.22 (Standard deviation = 2.89), figure 5.


Age of dogs with  High blood  pressure

In large breed dogs with high blood pressure (Rotwailler, Aikito, Schnautzer, Dog german, Caucazian) the mean age was 8.47 ± 0.67 (Standard deviation 2.88).
We have not observed:
-   correlations between TAD, TAM or TAD values and Pulse value;
-   a incidence of breed on high blood pressure (figure 6).


Incidence of High blood pressure depending on the breed
1. Mixed breeds; 2. German shepherd; 3. Cocker spaniel; 4. Boxer; 5. Rotwailler; 6. Caniche; 7. Brac; 8. Setter; 9. Pekinez; 10. Fox terrier; 11. Labrador, Retriever, Collie, Doberman pinscher; 12. Great Dane, Amstaff, Romanian shepherd; 13. Airedale terrier, Schnautzer, Teckel, Caucazian, Aikito, Pitbull.

Depending on blood pressure values and on clinical signs, the animals were placed in 4 groups proposed by “Guidelines for The Identification, evaluation and Management of Systemic Hypertension in Dogs and Cats” (Brown S. and col., 2007). The cause of high arterial  blood pressure couldn’t be established in most of cases (difficulties in hormonal determinations et al.).

CONCLUSIONS

  1. Arterial hypertension was diagnosed in 10.32% of examined dogs in a 5 month period. Blood pressure determination was realized using the oscilometric method and a Memo Diagnostic MDPRO Cat + Dog Blood pressure device. 5 determinations were done for each animal and the average was calculated.
  2. Diagnosis was based on the increase of systolic mean and diastolic blood pressure correlated with specific clinical signs: nervous signs (apathy, uncoordinated movements, head shoving of the wall), ocular signs (blindness, hemorrhage of the retina, detached retina), epistaxis, limbs edema, heart failure  failure signs (fatigue, dispnoea, cough), renal signs (oedema, polyuria - polydipsia, creatinine increase).
  3. Diagnosis of high blood pressure was established at values higher than 150 mm Hg PAS and 90 mm Hg PAD. High values obtained in excited animals were checked using multiple determinations. When high values of blood pressure were obtained, but there were no specific clinical signs, the animal was double checked. Only in the situations when high blood pressure was obtained in all determinations, the animal was considered hypertensive. According to the values obtained, the animals were included in one of the 4 risk grades, proposed by High blood pressure evaluation guide in dogs and cats.
  4. PAS values (the total number of hypertensive animals), was 182.015±1.53 mm Hg (Standard deviation = 19.85). Mean arterial blood pressure was 135.00±1.31 mmHg (Standard deviation = 15.98) and PAD = 113.53 ±1.18 mm Hg (S.D. = 14.28).
  5. Age of hypertensive animals was 10.45±0.22 (S.D.=2.89). In large breed dogs, mean age was 8.47±0,67 (S.D.= 2.88).
  6. There was no correlation observed between the HTA (Systemic Hypertension)  incidence and sex of the animals.
  7. Conclusively, HTA is a condition that affects adult dogs and has repercussions on the entire body. This fact recommends that blood pressure determinations become a routine determination in clinical practice.
  
Bibliography

Bodey A.R., Michell A.R., 1996 –  Epidemiological study of blood pressure in domestic dogs. J. Small Anim. Pract., 37, 3, 116 - 125.
Brown S., Atkins C., Bagley R., Carr A., Cowgill L., Davidson M., Egner B., Elliott J., Henik R., Labato M., Littman M., Polzin D., Ross L., Snyder P., Stepien R., 2007 –  Guidelines for the Identification,  Evaluation, and Management of Systemic Hypertension in dogs and  cats. J. Vet. Int. Med., 21, 542 - 558.
Egner Beate, Carr A., Brown S., 2007 – Essential Facts of Blood Pressure in Dogs and Cats. A  reference  guide. ed. IV. VBS VetVerlag, Babenhausen, Germany.
Remillard R.L., Ross J.N., Eddy J.B., 1991 – Variance of indirect blood pressure measurements and prevalence of hypertension in clinically normal dogs. Am. J. Vet. Res., 52, 4, 561 - 565.
Stepien Rebecca L., Henik Rosemary A., 2009 –  Systemic Hypertension. In: Bonagura J.D., Twedt D.C. - Kirk’s. Current Veterinary Therapy XIV. Saunders, Elsevier.

















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