Abstract
Objectives
The aim of the present study was to assess the accuracy of weight estimation in cats provided by pet owners, veterinary technicians, house officers (interns and residents) and attending clinicians in an emergency room (ER). An additional objective was to determine whether carrying the cat contributed to a more accurate weight estimate.
Methods
A total of 72 cats presented to an ER and were enrolled in the study. Pet owners, veterinary technicians, house officers and attending clinicians were asked to record the cats’ estimated weights on individual data collection cards. The actual weights of the cats were then obtained and compared with participants’ estimations.
Results
There were no significant differences between weight estimates provided by pet owners, veterinary technicians, house officers and attending clinicians. Similarly, neither the length of experience of the veterinary staff nor carrying the cat had an effect on the provision of a more accurate weight estimate.
Conclusions and relevance
Pet owners are no better at weight estimation of cats in the ER setting compared with veterinary professionals. Carrying the cat did not improve the accuracy of weight estimation among veterinary professionals. The mean cat weight of 4.9 kg could be used as an average cat weight in an emergency situation for an adult cat.
Introduction
Obtaining an accurate weight measurement in veterinary patients that present in unstable conditions can occasionally be incredibly challenging, particularly in cats. This is potentially due to a variety of factors, including cats that present in a critical condition and require immediate intervention, the tendency for cats to experience increased anxiety or distress compared with dogs, and a greater need to reposition cats on the scale during weight measurement due to their natural tendency to seek hiding places. 1 Furthermore, veterinary staff may be less confident handling cats compared with dogs. 2 Cardiopulmonary arrest, congestive heart failure, severe asthma crisis or active seizure are common conditions in which quick decision-making, utilizing an appropriate dose of medications, is essential. In addition, several other resuscitation modalities, including fluid therapy and electrical defibrillation, require an immediate knowledge of the cat’s body weight. In cases where an accurate weight cannot be safely or quickly and easily obtained, weight estimates are frequently utilized for emergency interventions.
Physicians have the same challenge when pediatric and adult human patients are evaluated in the emergency room (ER) in emergency conditions. 3 This has led to the exploration of different methods for weight estimation in human patients, especially in children. These include age-based formulas, age on clothes size labels, size length-based systems, tools such as Broselow weight tapes or relying on the parents’ estimates.4–8 Several factors have been demonstrated to influence the accuracy of weight estimation by human ER professionals, including the patient’s age, level of patient cooperation, body condition (ie, presenting under- or overweight) and the professional’s level of experience. 9 Both original prospective studies and systematic reviews, mostly in children, have demonstrated that the parents’ estimation is more accurate than the medical professionals’ estimation and the use of other weight-estimation tools. 5 In one study evaluating the accuracy of weight estimation in patients, 84% of parents, 60% of nurses and 71% of physicians provided weight estimates that were within 15% of the child’s actual weight. 10
A similar finding was recently described in dogs, where pet owners estimated their dogs’ weight with higher accuracy compared with veterinary professionals in an ER. 11 Interestingly, the study also demonstrated that veterinary professionals were less accurate in estimating the weight of smaller dogs compared with larger dogs. A previous veterinary study investigated weight estimation in cats presented to an ER, although the weight estimate of the pet owner was not included in this study. As body condition score (BCS) increased, veterinary professionals overestimated the cats’ body weight. Approximately 20% (6/28) of weight estimations in cats were within 10% of the cat’s actual body weight. 12
Unlike dogs, cats tend to have a narrower range of body weights, which may make weight estimation easier. The impact of estimating a higher or lower body weight in making treatment decisions is likely also less significant in cats due to their average smaller body weight compared with dogs. The objective of the present study was to examine the accuracy of weight estimates provided by pet owners compared with veterinary professionals. A second objective was to evaluate the influence of carrying the cat on the accuracy of weight estimation. We hypothesized that pet owners would provide more accurate and reliable body weight estimates compared with veterinary professionals, and that carrying the cat would contribute to more accurate weight estimations among veterinary professionals.
Materials and methods
Ethical approval
An approval from the Institutional Animal Care and Use Committee was considered unnecessary by the committee as there was no manipulation of vertebrate animals. The study underwent review by the University of Florida Institutional Review Board and was approved as exempt. Questions posed to pet owners were part of obtaining a routine history and did not require separate consent from the clients other than the standard consent provided at the time of admission.
Study design and inclusion criteria
This prospective observational study was performed in the ER at the Small Animal Veterinary Teaching Hospital of the University of Florida between 1 June and 29 July 2022. Data were directly entered into specially designed data collection cards. The eligibility of cats enrolled in the study was determined based on the availability of the individual responsible for organizing data collection (NB) in the ER. Veterinary professionals were enrolled in the study if they were working during a shift when data collection was taking place.
Cats with a weight of less than 2 kg or those that could not be weighed using a veterinary scale were excluded. Cats triaged through the isolation ward were also excluded. In addition, veterinary technicians, house officers (small animal rotating interns, emergency and critical care interns, and emergency and critical care residents) and attending clinicians (including board-certified critical care specialists and emergency doctors) were excluded if they had prior knowledge of the cat’s weight or had overheard it before filling out a data collection card.
Procedures and data collection
For each cat included in the study, a veterinary technician, house officer and attending clinician were asked to complete a data collection card. The data collection card included the following information: the cat’s name, medical record number and signalment; the veterinary professional’s first and last name; the veterinary professional’s estimate of the cat’s weight; whether the cat was carried by the veterinary professional before the weight estimate was provided; and the veterinary professional’s length of veterinary experience (in years, sum total of veterinary experience before and after graduation from veterinary school). Each veterinary professional completed a new data collection card for each cat enrolled in the study. They were instructed to write down their estimate of the cat’s weight (converted to kilograms if provided in pounds) without audibly verbalizing it to avoid influencing other participating members of the team.
Each client was asked to provide a weight estimate for their cat (converted to kilograms if provided in pounds) while the client was in the ER lobby or a private room away from members of the ER staff participating in the study. The client also provided the length of time they had owned their cat (in years). The cats were then weighed in the triage area of the ER on a small scale for cats (BD-585 Feline/Puppy Scale; Tanita). The cat’s actual weight was recorded on the data collection cards after participant estimations had been recorded. Information from the data collection cards was imported into an Excel spreadsheet (Microsoft Corp). Mean percentage error in weight estimation, calculated as the absolute difference between estimated and actual weight divided by actual weight and then converted into a percentage, was calculated for the veterinary technician, house officer, attending clinician and pet owner. The absolute percentage error was calculated as the absolute value ([estimated value – actual value] / actual value). The estimation bias was determined as the difference between the estimated weight and the actual weight. Accuracy categories for each group of estimators were defined as within 5%, 10%, 20% and above/below 50%.
Statistical analysis
Statistical analyses were performed using SAS software (version 9.4 release TS1M7; SAS Institute). Normally distributed data were reported as mean ± SD (range). Spearman’s rank correlation (signified by rs) was used to measure the strength of association between two variables because of an outlier and non-normally distributed data. The correlation coefficient (rs) is in the range of –1 to 1. The absolute values of rs were categorized as weak (0–0.39), moderate (0.4–0.59), strong (0.6–0.79) or very strong (0.8–1). The Mann–Whitney U-test and Kruskal–Wallis test were used to compare the estimation bias difference between experienced and less experienced staff members, and weight groups. A one-way repeated-measures ANOVA was used to compare the estimation bias among veterinary technicians, house officers and attending clinicians. Estimation bias was evaluated using square root transformation to meet normality assumption. A P value <0.05 was considered significant.
Results
During the study enrollment period, 1235 cases were seen through the ER; 1163 cases were excluded because they were dogs, the individual organizing data collection (NB) was not working when those cases were evaluated or the cats weighed <2 kg. Thus, 72 cats were enrolled in the study. Of the 72 cats, 62 (86%) were domestic shorthair, four (6%) were domestic mediumhair, three (4%) were domestic longhair, two (3%) were Siamese and one (1%) was a Devon Rex. The mean age was 7.28 ± 5.84 years (range 0.42–28) and the mean actual body weight was 4.91 ± 1.48 kg (range 2.12–8). The majority of cats were male (46/72, 65%) and there were 25 female cats and one cat whose sex was not recorded.
In total, 72 pet owners, 21 veterinary technicians, 21 house officers and 11 attending clinicians participated in the study. A total of 72 weight estimations were provided by technicians and house officers, 71 by attending clinicians and 70 by pet owners. On average, the attending clinicians had the most experience (median 17 years vs 8 years and 3 years for veterinary technicians and house officers, respectively), while pet owners had owned their cat for a median of 4 years.
Approximately 59% (41/70) of pet owners, 33% (24/72) of veterinary technicians, 50% (36/72) of house officers and 38% (27/71) of attending clinicians provided weight estimates within 10% of the cat’s actual body weight (Table 1).
Percentages of body weight estimates provided by pet owners, technicians, house officers and attending clinicians, stratified within 5%, 10%, 20% or >50%/<50% of the actual measured body weights for 72 cats presented to an emergency room
Data are n/n (%)
Body weight estimates provided by pet owners were the most accurate in terms of median difference from the actual body weight (0.34 kg, range 0–4.66), followed by the house officers (0.52 kg, range 0–3.04), attending clinicians (0.59 kg, range 0–3.26) and veterinary technicians (0.73 kg, range 0.02–3.73). Pet owners, veterinary technicians, house officers and attending clinicians were all likely to overestimate the cat’s body weight (Table 2).
Percentages of under- or overweight estimates provided by pet owners, veterinary technicians, house officers and attending clinicians based on the cats’ actual measured body weights
Data are n/n (%)
When specifically evaluating the absolute percentage error, we found no statistical difference among the four groups of estimators. In addition, there was no significant correlation noted between the veterinary professionals’ length of experience and the accuracy of estimating the cats’ body weight, although there was a weak negative correlation between the length of experience and the absolute percentage error (rs = −0.18 for house officers, rs = −0.15 for attending clinicians and rs = −0.04 for veterinary technicians). Carrying the cat did not improve the accuracy of weight estimation for veterinary technicians, house officers or attending clinicians. Finally, the length of time that the cat had been owned by the client had a positive weak correlation with the absolute percentage error estimate bias (P = 0.01 and rs = 0.30) and the absolute difference (P = 0.006 and rs = 0.33).
Discussion
Based on the results of the present study, pet owners did not provide a more accurate weight estimate compared with veterinary professionals, thus rejecting our original hypothesis. This is in contrast to findings, including systematic reviews, reported in humans and a recent study in dogs. 11 The reason(s) for the reduced accuracy of pet owners’ estimates of their cats’ weight is unclear. However, a low number of visits per year to a veterinary facility for preventive care and lack of effective client–veterinarian communication regarding weight may represent important contributors.13–15 In addition, dog owners may have a heightened awareness of their dogs’ weight due to their involvement in situations where weight information is necessary to register their dogs for housing, travel, daycare and social activities. In contrast, cat owners are less likely to partake in such activities, potentially leading to less awareness of their pets’ precise weight.
The lack of statistical significance found in this study aligns with previous human and veterinary studies, which suggest that the accuracy of weight estimation tends to be compromised by underweight children and small dogs, respectively.9,11,16 A previous study by Wolf and Drobatz 12 demonstrated that a higher BCS induced overestimation of cats’ weight by veterinary staff. The cats’ BCS was not evaluated in this study. Thus, it is unclear whether the BCS affected the weight estimation of the estimators. Moreover, pet owners may be less willing to admit their cats are overweight, as they have been found to underestimate BCS and obesity.17,18 In contrast, pet owners and veterinary professionals were more likely to overestimate the weight of the cats in this study.
Contributing factors for better weight estimation accuracy in cats, such as carrying the cat and the length of experience of the veterinary professionals, were also evaluated. However, there was no significant effect of either factor on weight estimation accuracy. In contrast, house officers (ie, interns and residents) and veterinary technicians gave more accurate weight estimates for dogs that were carried, although this was not observed when dogs were carried by attending clinicians. 11 Potential contributors to these findings in cats, such as BCS and hair coat length, were not evaluated in the present study and could have influenced the final results, as these factors have been found to affect pet owners’ perceptions of weight and obesity. 19
To the authors’ knowledge, this is the first study evaluating the weight estimation of cats in an ER setting that incorporates the pet owners’ estimations. Although cat owners were not able to provide a more precise body weight for their pets than veterinary staff, they were the most accurate group when considering the median difference in their estimation from their cat’s actual weight. On the other hand, veterinary technicians had the least accurate estimations; similar findings were obtained for veterinary technicians’ estimation of dog weights. 11 Therefore, it may be appropriate to consider the estimation of the pet owner during triage in the ER when an accurate weight cannot be obtained.
This study also evaluated whether carrying cats in the ER setting contributed to improving weight estimates. However, this factor was not significantly correlated with estimation accuracy among the groups studied. This finding, together with the fact that, in dogs, more inaccurate weight estimations were found in small dogs (<5 kg) compared with large dogs (>10 kg), 11 suggests that both pet owners and veterinary professionals are unable to distinguish variations in lighter weights. Therefore, intentionally carrying cats to estimate their weight when in life-threatening conditions should be avoided since this does not improve accuracy and contributes to additional delays in their treatment. Montmany et al 20 demonstrated that delay in starting the appropriate treatment in the emergency setting represents the main cause of death in human patients after trauma. Working on treatment tables that simultaneously serve as scales or having scales readily accessible at the location of triage may mitigate these limitations.
The mean weight of cats in this study was 4.91 kg. The authors propose that a weight of 4–5 kg is a reasonable estimate for adult cats that present in an emergency situation and are unable to be weighed (although cats weighing under 2 kg were excluded from this study, and including them may have led to a lower mean weight). This will be similar to considerations made in the human ER where adults are treated based on an average weight for human patients (fixed-dose regimen). Many studies have found fixed-dose protocols to be non-inferior, or in some cases superior, to weight-based dosing protocols in human patients in the ER.21–25 This is a reasonable proposal because of the limited variability in body weight in cats and human adults as opposed to children and dogs. The authors feel comfortable with this recommendation because even with a 50% error when utilizing a 5 kg weight, there are minimal adverse effects anticipated with most emergency interventions due to the range of therapeutic doses for those medications (fluid therapy, analgesia, drugs for cardiopulmonary resuscitation). With most emergency drugs, the clinician would still provide interventions within safe and therapeutic ranges. Special considerations should be made for cats that appear to be particularly underweight/overweight, but this allows immediate intervention until an accurate weight can be obtained. In addition, using a weight estimate of 4–5 kg should be applied cautiously in cats with underlying heart disease, where fluid therapy should be closely tapered to the cat’s weight. This recommendation does not apply to interventions with narrow therapeutic ranges (ie, chemotherapeutic drugs), although those are not utilized on an emergency basis. Moreover, studies evaluating the estimated weights of cats less than 2 kg (including pediatric and neonatal kittens) are still also necessary since they were excluded from this study.
The challenge in obtaining reliable weight estimates in cats inspires preventive measures that should be considered in healthy cats for future admissions to the ER. These may include better verbal and written client communication where the cat’s weight is clearly documented and highlighted, labeling the cat’s carrier with the date and weight of the cat and/or carrier before hospital discharge, and/or the use of identification collars that include weight information.
Conclusions
The results of the present study revealed no significant difference between the weight estimations of cats provided by pet owners and veterinary professionals. Moreover, the length of experience and carrying the cat did not contribute to improved weight estimation by veterinary professionals. While not statistically significant, pet owners, on average, were more accurate than veterinary professionals in estimating cats’ weights. Therefore, when the actual body weight of cats experiencing life-threatening emergencies cannot be obtained, a standard weight of 4–5 kg may be considered.
Footnotes
Conflict of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
This research was supported by the Linda F Hayward Florida Veterinary Scholars Program and the University of Florida College of Veterinary Medicine.
Ethical approval
The work described in this manuscript involved the use of non-experimental (owned or unowned) animals. Established internationally recognized high standards (‘best practice’) of veterinary clinical care for the individual cat were always followed and/or this work involved the use of cadavers. Ethical approval from a committee was therefore not specifically required for publication in JFMS. Although not required, where ethical approval was still obtained, it is stated in the manuscript.
Informed consent
Informed consent (verbal or written) was obtained from the owner or legal custodian of all animal(s) described in this work (experimental or non-experimental animals, including cadavers) for all procedure(s) undertaken (prospective or retrospective studies). No animals or people are identifiable within this publication, and therefore additional informed consent for publication was not required.
