Evaluation of the effects of hospital visit stress on physiologic variables in dogs

Ryan F. Bragg Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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Jennifer S. Bennett Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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Annelise Cummings Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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Jessica M. Quimby Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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Abstract

Objective—To evaluate differences in pulse rate, rectal temperature, respiratory rate, and systolic arterial blood pressure in dogs between the home and veterinary hospital environments.

Design—Prospective observational study.

Animals—30 client-owned healthy dogs.

Procedures—Study dogs had respiratory rate, pulse rate, rectal temperature, and systolic arterial blood pressure measured in their home environment. Dogs were then transported to the veterinary hospital, and measurements were repeated.

Results—Significant differences in blood pressure, rectal temperature, and pulse rate were observed between measurements obtained in the home and hospital environments. Mean blood pressure increased by 16% (95% confidence interval [CI], 8.8% to 24%), rectal temperature increased by < 1% (95% CI, 0.1% to 0.6%), and pulse rate increased by 11% (95% CI, 5.3% to 17.6%). The number of dogs panting in the hospital environment (19/30 [63%]) was significantly higher than the number of dogs panting in the home environment (5/30 [17%])

Conclusions and Clinical Relevance—Results of the present study suggested that practitioners should consider stress from transportation and environmental change when canine patients have abnormalities of vital signs on initial examination, and the variables in question should be rechecked before a definitive diagnosis of medical illness is reached or extensive further workup is pursued.

Abstract

Objective—To evaluate differences in pulse rate, rectal temperature, respiratory rate, and systolic arterial blood pressure in dogs between the home and veterinary hospital environments.

Design—Prospective observational study.

Animals—30 client-owned healthy dogs.

Procedures—Study dogs had respiratory rate, pulse rate, rectal temperature, and systolic arterial blood pressure measured in their home environment. Dogs were then transported to the veterinary hospital, and measurements were repeated.

Results—Significant differences in blood pressure, rectal temperature, and pulse rate were observed between measurements obtained in the home and hospital environments. Mean blood pressure increased by 16% (95% confidence interval [CI], 8.8% to 24%), rectal temperature increased by < 1% (95% CI, 0.1% to 0.6%), and pulse rate increased by 11% (95% CI, 5.3% to 17.6%). The number of dogs panting in the hospital environment (19/30 [63%]) was significantly higher than the number of dogs panting in the home environment (5/30 [17%])

Conclusions and Clinical Relevance—Results of the present study suggested that practitioners should consider stress from transportation and environmental change when canine patients have abnormalities of vital signs on initial examination, and the variables in question should be rechecked before a definitive diagnosis of medical illness is reached or extensive further workup is pursued.

Temperature, pulse rate, respiratory rate, and blood pressure are the 4 vital signs that are often measured in veterinary patients and serve as the primary objective measurements of the physical examination. Normal values frequently reassure the clinician of the general health of the patient, whereas abnormalities of these variables lead clinicians down various diagnostic pathways.

A critical factor in this analysis and decision-making process is whether elevations in these vital signs are clinically important or whether they are merely artifacts caused by the patient being in a medical setting. In human medicine, a patient's blood pressure is higher at the doctor's office than at his or her home, a phenomenon known as the white-coat effect.1 A 2008 study found that 60.3% of 224 human patients attending a lipid screening clinic experienced the white coat effect when their blood pressure was measured by a doctor during a clinic visit.2

Whether an analgous effect also exists in companion animals has been studied, but to a much lesser extent than in humans. In cats, a significant increase in blood pressure was demonstrated in research colony cats when comparing a 24-hour radiotelemetric implant measurement in the colony environment with the blood pressure measured in a simulated veterinary clinic.3 Additional studies have found significant differences in pulse rate, respiratory rate, and indirectly measured blood pressure in cats when measurements made in the home were compared with those obtained in a veterinary hospital.3–5 In dogs, Kallet et al6 found that there was a significant increase in pulse rates measured at the clinic versus at home and a higher, albeit not significantly increased, blood pressure at the clinic versus at home. Another study7 found no significant increase in blood pressure in dogs in the hospital, compared with at home, when measured by use of the Doppler technique and the right cranial tibial artery. Unlike for blood pressure and pulse rate, a search of the literature did not yield any studies evaluating differences in temperature and respiratory rate in dogs in a home environment versus a veterinary hospital.

The purpose of the study reported here was to compare values for the 4 major vital signs (temperature, pulse rate, respiratory rate, and blood pressure) for healthy dogs in their home environment and at a veterinary hospital. Our hypothesis was that the measurements taken in the hospital environment would be significantly higher than those taken in the home environment.

Materials and Methods

Dogs—An observational crossover study was designed. A priori power analysis was performed for blood pressure with an α of 0.05, expected difference of 10% (we considered differences > 10% to be clinically important), and SD of 15 mm Hg (on the basis of previously reported data from our group collected in cats5). On the basis of these variables, inclusion of 30 dogs in the study would result in a power of 94%. The study protocol was reviewed and approved by the Colorado State University Animal Care and Use Committee, and all owners read and signed a client informed consent form prior to enrollment. Client-, staff-, and student-owned dogs were included if they met the following inclusion criteria: age between 1 and 10 years and body weight between 7 and 70 kg. The subjects were determined to be healthy on the basis of results of physical examination and owner-provided history at the time of study enrollment. No provision (inclusion or exclusion) for dogs with an excitable temperament was made. Exclusion criteria included dogs with known preexisting cardiac, renal, endocrine, or respiratory abnormalities.

Study design—In this study, physiologic variables were measured in 2 environments: the owner's home and a hospital examination room. All measurements were taken by 2 veterinary student investigators (AC and JSB) working individually. Student investigators were trained in the proper operation of the blood pressure apparatus by the principle investigator (JMQ) and were observed competently obtaining blood pressure measurements to ensure proper data collection before the start of the study. The student investigator first met the dog and its owner at their home. Physiologic variables were measured approximately 10 minutes after arrival of the investigator in the home, after study protocol details had been explained and informed consent paperwork signed. The investigator recorded the respiratory rate by counting chest wall movements of the dog for 15 seconds and then multiplying by 4 to determine the per-minute rate. If the dog was open mouth breathing with a rate > 80 breaths/min with no evidence of dyspnea, the rate was recorded as panting. Pulse rate was recorded by palpating the femoral pulse for 15 seconds and then multiplying by 4 to determine beats per min. Rectal temperatures were obtained with a single digital thermometera and recorded to the tenth of a degree. Systolic arterial blood pressure was obtained by the indirect Doppler method.b Animals were placed in right lateral recumbency and restrained by the owner. Blood pressure cuffs were sized to 40% of the circumference of the left forelimb distal to the elbow. The crystal was placed over the left median artery immediately proximal to the metacarpal pad. Ultrasound gel and alcohol were used to facilitate accurate measurements. Blood pressure measurements were repeated until a series of 3 consistent readings (within 5 mm Hg) were obtained. Immediately following blood pressure measurement in the home environment, the dogs were transported by the owner to James L. Voss Veterinary Teaching Hospital at Colorado State University. Transportation time was predetermined to be a minimum of 10 minutes and maximum of 35 minutes. Owners who lived < 10 minutes from the hospital were asked to drive with the dog in the vehicle until at least 10 minutes had passed before proceeding to the hospital. Wait time in the veterinary clinic lobby was predetermined to be a minimum of 10 minutes and maximum of 35 minutes. The study was performed after hours and on weekends, and ≤ 5 other clients were present in the lobby at these times. The same investigator who took the measurements in the home environment took the participant to an examination room and repeated the measurements in the same order with the same time frame between measurements as performed at home. The only difference was that the investigator wore a white laboratory coat in the examination room.

Statistical analysis—Data were assessed for a normal distribution by means of the Kolmogorov-Smirnov normality test, and all variables except respiratory rate in the home environment were found to be normally distributed. Continuous variables were analyzed with a Wilcoxon signed rank test. Categorical variables were analyzed with a Fisher exact test. Mean blood pressure measurements were used for analysis. Respiratory rates measured when dogs were panting were excluded from analysis. Values of P ≤ 0.05 were considered significant. Bland-Altman graphs were prepared to visually represent agreement between physiologic variables. Analyses were performed with statistical software.c

Results

Thirty dogs (19 males and 11 females) completed the study. All dogs were neutered and ranged in age from 1 year to 10 years (median, 4.5 years; mean ± SD, 4.9 ± 2.6 years). Weight ranged from 10.2 to 57.2 kg (median, 26.4 kg; mean ± SD, 27.8 ± 11.5 kg). Fourteen different breeds were represented including mixed breed (15), Labrador Retriever (2), Australian Shepherd (2), and one each of pit bull–type dog, Great Pyrenees, Walker Hound, Basset Hound, Redbone Coonhound, Greyhound, Wire Fox Terrier, German Shepherd Dog, Blue Heeler, Shetland Sheepdog, and Siberian Husky.

Physiologic variables at home and in the hospital environment were summarized (Table 1). Significant differences in blood pressure, rectal temperature, and pulse rate were observed between measurements taken in the home and hospital environments. Mean blood pressure increased by 16% (95% CI, 8.8% to 24%; P = 0.001); median increase when in the clinic was 20.5 mm Hg (range, −50 to 68 mm Hg). Rectal temperature increased by < 1% (95% CI, 0.1% to 0.6%; P = 0.008); median increase when in the clinic was 0.2°C (0.3°F; range, −0.44° to 1.06°C [–0.8° to 1.9°F]). Pulse rate increased by 11% (95% CI, 5.3% to 17.6%; P = 0.001); median increase when in the clinic was 10 beats/min (range, −10 to 44 beats/min). Respiratory rate increased by < 1% (95% CI, −7% to 24%); median increase when in the clinic was 1 breath/min (range, −5 to 14 breaths/min), but the change was not significant (P = 0.29). The number of dogs panting in the hospital environment (19/30 [63%]) was significantly (P < 0.001) higher than the number of dogs panting in the home environment (5/30 [17%]). Physiologic variables in the home and hospital environments were depicted as Bland-Altman plots (Figure 1) to allow the variability between environments to be visually appreciated for each subject.

Figure 1—
Figure 1—

Bland-Altman plots comparing rectal temperature (A), pulse rate (B), and blood pressure (C) for 30 healthy dogs between home and clinic environments. The horizontal line represents no difference. Values above the line were increased in the clinic environment. Most dogs enrolled had some increase in blood pressure (24/30), rectal temperature (22/30), and pulse rate (22/30) in the clinic environment. Respiratory rate is not graphically depicted owing to the high incidence of panting in the hospital. Analysis with a Wilcoxon signed rank test indicated a significant difference between the home environment and the veterinary hospital environment for rectal temperature (P = 0.008), pulse rate (P = 0.001), and blood pressure (P = 0.001).

Citation: Journal of the American Veterinary Medical Association 246, 2; 10.2460/javma.246.2.212

Table 1—

Physiologic variables in healthy dogs (n = 30) in the home environment versus in the hospital environment.

 Home environmentClinic environment  
VariableMean ± SDMedian (range)Mean ± SDMedian (range)Change (%)95% CI
Blood pressure (mm Hg)*122 ± 29114 (86–201)139 ± 31138 (84–210)168.8 to 24
Rectal temperature (°C)*38.44 ± 0.4438.33 (37.44–39.56)38.61 ± 0.3938.56 (38.0–39.67)< 10.1 to 0.6
Pulse rate (beats/min)*88 ± 1687 (50–118)97 ± 2198 (64–146)115.3 to 17.6
Respiratory rate (breaths/min)31 ± 928 (20–56)30 ± 828 (17–44)< 1–7 to 24

Values are significantly (P < 0.05) different between home and clinic environments.

Discussion

In the present study of potential differences in physiologic variables in 30 healthy dogs, significant increases in rectal temperature, pulse rate, panting incidence, and systolic arterial blood pressure were observed in the hospital environment, compared with the home environment. These results most likely stemmed from the activation of the sympathetic nervous system and should be taken into account when assessing patients in the veterinary hospital setting.4,8,9 This activation could be caused by a number of factors, including exposure to new people, being in a new building, excitement of transportation, restraint, scent and sight of different animals, anxiety associated with the measurement process, and low-grade discomfort associated with rectal thermometer placement.

The changes documented in systolic arterial blood pressure between the home and hospital environment in dogs in the present study were considered clinically relevant, with a mean increase of 16% (95% CI, 8.8% to 24%; P = 0.001) and the largest individual increase of 68 mm Hg (57% increase). In humans, the white-coat effect is a well-documented phenomenon, and similar effects have previously been documented in dogs and cats.3,6,7 Therefore, if elevated blood pressure is documented, a white-coat effect should be considered and the blood pressure subsequently rechecked.10 If blood pressure is severely elevated or consistently high or target organ damage is present, clinicians should pursue diagnostic testing to identify an underlying cause and institute medical treatment.10

The mean elevation in pulse rate in the hospital environment (11%; 95% CI, 5.3% to 17.6%) was significant (P = 0.001); changes > 10% in this variable are likely to be clinically relevant. In contrast, the mean elevations in rectal temperature of 0.17°C (< 1%; 95% CI, 0.1% to 0.6%; P = 0.008) and respiratory rate of 2 breaths/min (< 1%; 95% CI, −7% to 24%; P = 0.29) fall within the normal range11 and are unlikely to be clinically relevant. However, the potential clinical relevance of these physiologic variables is perhaps best described by assessing the largest observed individual increases. Specifically, the highest recorded increases in pulse rate, respiratory rate, and temperature were 44 beats/min (43% increase), 14 breath/min (46% increase), and 1.06°C respectively. Additionally, 3 dogs with rectal temperatures < 39.17°C (102.5°F) in the home environment subsequently had temperatures > 39.17°C in the hospital environment. In a similar study5 by our group evaluating cats, no significant increase in rectal temperature was found in the hospital environment, compared with the home environment (mean ± SD increase, 0.17 ± 0.33°C [0.3° ± 0.6°F]).5 However, in both the prior study of cats5 and the present study of dogs, a few individual animals developed an elevated rectal temperature purely as a result of transport and assessment in the hospital setting. Therefore, as with blood pressure, unless severe, elevated temperature and heart rate should be rechecked and confirmed before a diagnostic workup is initiated.

The comparison of respiratory rate between the home and hospital environments in this study was somewhat confounded by the number of dogs that began to pant in the hospital environment. Panting is a normal variant of breathing, but differential diagnoses for unrelenting panting in the home or hospital environments include pain, anxiety, metabolic acidosis, or endocrinopathy. Panting has been correlated with increased salivary cortisol concentrations, representative of increased sympatho-medullary-adrenal axis activity, in the hospital setting.9 On the basis of the significant increase in panting incidence in healthy dogs in the hospital environment, this should be considered a likely white-coat effect. However, if panting is severe or unrelenting and heat exposure has been ruled out, then an underlying disease should be considered. Measurement of physiologic variables may be affected by the order in which they are obtained. In this study, measurements were obtained for variables in order of restraint required, from least to most. However, given that rectal temperature was obtained prior to blood pressure measurement, some effect on blood pressure is possible. To minimize effects as much as possible for comparison, the order in which measurements were obtained and the timing of measurements was kept constant between the 2 environments. Obtaining measurements in the home environment could also have potentially been affected by the novelty of a visitor, inducing excitement or anxiety in the study participant. Although an acclimatizing period was part of the protocol and most parameters measured in the home environment were within commonly accepted normal ranges (values for rectal temperature were within 37.22° to 39.17°C [99° to 102.5°F] in 28 of 30 [93%] dogs; pulse rates were within 60 to 120 beats/min for 27 of 30 [90%] dogs; values for blood pressure were within 90 to 150 mm Hg in 26 of 30 [87%] dogs; and values for respiratory rates were within 20 to 30 breaths/min for 20 of 30 [68%] dogs), there is a possibility this could have affected the results. This may indicate that just the act of measuring the variables can have an effect on the results and that, in this case, assessment of the white coat effect may be underestimated because of elevations in the baseline measurements obtained in the home environment.

In a small number of dogs in this study, measured physiologic variables decreased in the hospital environment, contrary to expectation. Potential explanations for this observation include a decrease within the normal variability of measurement technique, normal physiologic variation in the variable, acclimatization to the measurement technique, and elevated baseline measurement due to novelty of visitor to the home. However, the degree of decrease may not be clinically relevant and the implication of this observation is not fully understood.

Many dogs in the present study were large-breed dogs, and thus the results may not be representative of the general population. Another potential bias of this study is that all animals were neutered; however, this is representative of our general hospital population. Further studies should investigate whether there is greater difference in sexually intact versus neutered animals and small versus large dogs.

This study demonstrated that there was a significant increase in pulse rate, systolic arterial blood pressure, panting, and rectal temperature for healthy dogs examined in a home setting versus a veterinary hospital. Although mean differences in physiologic variables were not clinically relevant for some measured variables, the observed increases may be significant in individual animals. In general, when canine patients have abnormalities in rectal temperature, pulse rate, respiration, and systolic arterial blood pressure, stress from transportation and environmental change should be considered as differential diagnoses, and the variables in question should be rechecked before a diagnosis of medical illness is reached or further workup is pursued.

ABBREVIATION

CI

Confidence interval

a.

Vicks V966 Comfortflex with Insight, Kaz Inc, Hudson, NY.

b.

Parks Medial Electronics Inc, Aloha, Ore.

c.

Prism, version 6, GraphPad Software Inc, San Diego, Calif.

References

  • 1. Manios ED, Koroboki EA, Tsivgoulis GK, et al. Factors influencing white-coat effect. Am J Hypertens 2008; 21: 153158.

  • 2. Bo M, Comba M, Canadè A, et al. Clinical implications of white-coat effect among patients attending at a lipid clinic. Atherosclerosis 2008; 197: 904909.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3. Belew AM, Barlett T, Brown SA. Evaluation of the white-coat effect in cats. J Vet Intern Med 1999; 13: 134142.

  • 4. Abbott JA. Heart rate and heart rate variability of healthy cats in home and hospital environments. J Feline Med Surg 2005; 7: 195202.

  • 5. Quimby JM, Smith ML, Lunn KF. Evaluation of the effects of hospital visit stress on physiologic parameters in the cat. J Feline Med Surg 2011; 13: 733737.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6. Kallet AJ, Cowgill LD, Kass PH. Comparison of blood pressure measurements obtained in dogs by use of indirect oscillometry in a veterinary clinic versus at home. J Am Vet Med Assoc 1997; 210: 651654.

    • Search Google Scholar
    • Export Citation
  • 7. Remillard RL, Ross JN, Eddy JB. Variance of indirect blood pressure measurements and prevalence of hypertension in clinically normal dogs. Am J Vet Res 1991; 52: 561565.

    • Search Google Scholar
    • Export Citation
  • 8. Diepvens K, Kovacs EM, Vogels N, et al. Metabolic effects of green tea and of phases of weight loss. Physiol Behav 2006; 87: 185191.

  • 9. Hekman JP, Karas AZ, Dreschel NA. Salivary cortisol concentrations and behavior in a population of healthy dogs hospitalized for elective procedures. Appl Anim Behav Sci 2012; 141: 149157.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10. Brown S, Atkins C, Bagley R, et al. Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats. J Vet Intern Med 2007; 21: 542558.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11. Silverstein DC, Hopper K. Small animal critical care medicine. St Louis: Saunders Elsevier, 2009.

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