Abstract
Objectives
Ear-tipping practices and the meaning of the ear tip in trap–neuter–return (TNR) programs have not been well documented. The purpose of this study was to report the frequency of common ear-tipping practices in the USA, to identify the most effective methods and to establish a foundation for ear-tipping practice standards.
Methods
An anonymous 24-question survey was advertised from 4 to 20 October 2021 to individuals who participate in TNR programs that routinely perform ear tipping.
Results
There were 526 survey responses from individuals who participate in TNR programs, of whom 410 completed the survey. For ear-tip meaning, nearly 100% of respondents indicated that an ear tip meant that a cat had been sterilized. Several respondents answered that it also indicated rabies vaccination or socialization status, with 92 (22%) selecting both, 79 (19%) selecting rabies only and 50 (12%) selecting unsocial only. The majority of respondents tipped the left ear (81%), used a visual estimate to determine the cut (92%) and described the ideal silhouette as straight across (92%). The median percentage of cats where ear tips bled after initial hemostasis was 5% (interquartile range [IQR] 2–10), and the median percentage of negative feedback regarding the ear tip was 1% (IQR 0–5). In terms of weighted rank order, the most common feedback was that too much ear tip was removed (5.5), followed by a cat being ear tipped in error (4.7), persistent bleeding (4.2) and not enough ear tip being removed (4.2). Responses revealed heterogeneity regarding technique for both excision and hemostasis, as well as personnel performing the procedure. There were no significant associations between techniques and bleeding or negative feedback.
Conclusions and relevance
There is variation in the methods for performing an ear tip, as well as what an ear tip signifies. Standards for this procedure would be helpful.
Introduction
Ear tipping – the removal of the distal tip of the ear pinna – is an important visual marker for the identification of cats that have been sterilized as part of a trap–neuter–return (TNR) program for community cat population control.1–3 Ear tipping is performed under general anesthesia at the time of the spay/neuter surgery, to mark the cat as sterilized.1,2 Depending on the TNR program, cats may also receive vaccinations for rabies and other diseases plus other treatments.4,5
Systematic marking of sterilized cats is essential to the monitoring and evaluation of the success of TNR programs for community cat population control. 6 The ear tip provides a clear visual marker that can be viewed at a distance (up to 20 m with binoculars) without trapping the cat, thereby avoiding unnecessary stress to the individual.1,2 Although other marking and identification options (eg, tattoos and microchips) are used for cats, ear tipping is internationally accepted to be the most visible, recognizable and permanent method available to identify community cats as sterilized.7,8 The World Society for the Protection of Animals, the American Veterinary Medical Association, the Association of Shelter Veterinarians and the American Association of Feline Practitioners all promote ear tipping for the identification of sterilized community cats.2,9–11 Ear tipping is considered humane when performed as a sterile surgical procedure by a veterinarian under general anesthesia, including appropriate analgesia.2,8 Despite the acknowledged importance of the ear tip, no detailed or uniformly accepted standards for how to perform this procedure have been published in the peer-reviewed veterinary literature.
In the USA, guidelines and protocols, put forth by various organizations, vary in their recommendations regarding which ear should be tipped, how much should be removed, the timing of the ear-tip procedure relative to the spay/neuter surgery, and which tools and methods promote the desired silhouette.3,10–15 The left ear was originally recommended for the location of the ear tip: 1 some current recommendations follow this standard,12,13 while others do not specify which ear.3,9–11 The recommended amount of the distal ear tip that should be removed varies from 6 to 10 mm12,13 or one-quarter to one-third of the ear.3,10,14 One protocol recommends that the ear tipping is performed prior to the spay/neuter surgery, 12 while another recommends afterwards. 13 Recommended tools include scissors,3,13 a scalpel blade,12,14 electrosurgery 3 and a wood-burning tool (a heated metal tool used for decorative art.) 15 The desired silhouette is most commonly described as straight across perpendicular to the vertical axis of the ear pinna;3,10,13,14 ear notching is described as a less desirable alternative as it can be confused with traumatic injury or frostbite.3,10 Effective hemostasis is key for healing of a clean silhouette: recommended methods include use of a hemostat,3,12–15 styptic powder,12,14 compounded paste, 13 silver nitrate sticks,3,12 electrosurgery, 3 electrocautery 13 and/or a wood-burning tool. 15
The purpose of this study was to report the frequency of common ear-tipping practices, to identify the most effective methods and to establish a foundation for ear-tipping practice standards.
Materials and methods
A 24-question survey was created to gather information from individuals who participate in TNR or shelter–neuter–return programs in the USA that routinely perform ear tipping. Survey questions were piloted and then distributed via an electronic survey service (SurveyMonkey).
The survey was promoted via online forums and mailing lists of organizations involved with TNR, including the Association of Shelter Veterinarians, The Association for Animal Welfare Advancement, the Million Cat Challenge and the High Quality High Volume Spay Neuter Veterinarians Facebook group. Cross-posting to additional organizations and individuals who routinely perform ear tipping was encouraged. The survey was available from 4 to 20 October 2021.
Participation was voluntary and anonymous. No personally identifiable information was collected. Informed consent was provided on the first page of the online survey. This study was reviewed and found exempt by the Midwestern University Institutional Review Board (AZ IRBAZ-5042). The Checklist for Reporting Results of Internet E-Surveys (CHERRIES) was used to guide the survey reporting. 16
The survey requested basic demographic information, organization type, staff who perform the ear-tip procedure and number of ear-tip procedures performed monthly. Data were collected regarding the organization’s ear-tipping policies and protocols, including the meaning of the ear tip, tattoo identification in addition to ear tipping, ear-tipping protocols for specific case scenarios and which ear was routinely tipped.
Additional data were collected about the specific methods of the ear-tipping procedure, including timing relative to the spay/neuter surgery, tools used, amount of ear tip removal, measurement, desired silhouette and hemostasis. Respondents were asked how often they encountered persistent bleeding and negative feedback on their ear tips. A free-response question was included at the end of the survey allowing respondents to state anything they considered important regarding the topic but that was not covered in the survey. To reduce the possibility of survey abandonment, there were no mandatory/required responses. The full survey is available in Appendix 1 in the supplementary material.
Statistical methods
Statistics were performed using commercial statistical software (Stata 17; StataCorp). Descriptive statistics were performed, with non-normally distributed data reported as median and interquartile range (IQR). Percentages for questions that allowed respondents to select all responses that applied summed to more than 100, as multiple options could be selected. Kruskal–Wallis equality of population tests were performed to determine whether there were differences between the median of groups. Significant tests were followed by Dunn’s test of multiple comparisons with Sidák adjustment to identify which groups differed from each other. Ranked questions were reported with a weighted ranked order, with the average ranking calculated as follows, with w indicating weight of ranked position and x denoting response count for answer choice.
Free responses
Free responses were categorized by a single author (AMD). A new category was created for more than five similar novel responses to a question.
Results
Clinic demographics
There were 526 survey responses. Of these responses, 116 were excluded, with 30 not being associated with an organization that performed ear tips, 11 that did not choose a state or territory within the USA and 75 that completed <60% of the survey (respondents were not required to answer every question), leaving 410 responses. There were respondents from 46 US states, districts or territories, with Alaska, Delaware, North Dakota, Rhode Island, South Dakota and Wyoming not included in the responses. Respondents were primarily associated with animal shelters (53%, n = 216) and dedicated spay/neuter clinics that serve publicly owned animals, as well as community cats (29%, n = 120), with the remainder associated with dedicated TNR clinics focused exclusively on community cats (7%, n = 29), private practice (5%, n = 21), rescue organizations (3%, n = 14), academia (1%, n = 5) and ‘other’ (1%, n = 5).A median of 50 (IQR 20–120) cats were reported to be ear tipped each month. Of the main organization types, spay/neuter clinics reported the greatest number (median 100; IQR 40–200) and private practice the fewest (median 15; IQR 4–50). The number of cats tipped per month was different (P <0.001) according to organization type, with private practice, shelters and rescues performing fewer ear tips than spay/neuter clinics (Table 1).
Cats reported to be ear tipped per month by organization type
Difference as compared with spay/neuter clinic referent determined via a Dunn’s test with Sidák adjustment for multiple comparisons
IQR = interquartile range; TNR = trap–neuter–return
Ear-tip policies
When asked what the organization’s policy was with regard to ear-tipped cats presented for TNR, 199/410 (49%) responded that they would release cats that appeared healthy without examination or treatment, 148 (36%) would sedate to perform routine examination and/or treatment, 97 (24%) would rabies vaccinate without sedation, 58 (14%) would feline viral rhinotracheitis, calicivirus and panleukopenia (FVRCP) vaccinate without sedation and 12 (3%) would scan for a microchip. There were 79 novel free responses detailing case considerations, with the most common themes being treatment of obvious medical problems (n = 19), trapper preference (n = 6) and ruling out frostbite (n = 5). The majority (61%, n = 251) of the 410 respondents tattooed all cats that they ear tipped, with 67 (16%) tattooing only females and 92 (22%) not tattooing either sex.
Respondents were presented with two common scenarios regarding cats with indications that they may already have been sterilized. For the first scenario regarding a male cat (full question in Appendix 1), the majority (53%, n = 215) of the 408 respondents indicated that they would ear tip the cat but not tattoo. For the second scenario regarding a female cat (full question in Appendix 1), the greatest proportion (38%, n = 155) of the 409 respondents also indicated that they would ear tip but not tattoo, and a large proportion (31%, n = 128) indicated that they would surgically explore the cat followed by standard identification. Two free-text respondents indicated that they would perform a luteinizing hormone test (n = 2). The remainder of the responses to both scenarios were varied (Table 2).
Responses to question regarding protocol for males and females with a clinical indication that they may be sterilized
Data are n (%)
Meaning of ear tip
Almost 100% (n = 409/410) of respondents indicated that an ear tip meant a cat had been sterilized. Furthermore, large groups of respondents answered that it also indicated rabies vaccination or socialization status, with 92 (22%) selecting both, 79 (19%) rabies only and 50 (12%) unsocial only. Fourteen respondents generated a novel free-text response specifying that the ear tip indicates that the cat lived outdoors as a free-roaming or community cat (n = 10), had a caregiver (n = 3) or received an FVRCP vaccine (n = 1).
Ear-tipping practices
Ear tips were performed by a variety of personnel: veterinarians; credentialed veterinary technicians; veterinary technicians; veterinary assistants; veterinary students; veterinary technician students; and non-medical volunteers. Of the 410 respondents, 331 (81%) indicated that veterinarians performed the ear tip at least some of the time. Credentialed technicians (40%, n = 162), technicians (33%, n = 136) and assistants (24%, n = 100) were also commonly reported to ear tip at least some of the time. Of the 201 (49%) respondents reporting that only one entity performed the ear tip, the vast majority, 157 (78%), were performed solely by veterinarians, with technicians (10%, n = 21) and credentialed technicians (7%, n = 14) performing nearly all the remainder.
Most of the 410 respondents (81%, n = 334) reported exclusive tipping of the left ear, with 8% (n = 32) reporting exclusive tipping of the right ear, 1% (n = 3) reporting tipping the left for females and right for males, 4% (n = 17) reporting tipping the right for females and left for males, 6% (n = 23) reporting tipping either ear and one respondent reporting ‘other’. Of the 32 who reported exclusive tipping of the right ear, the majority were on the west coast: 15 (47%) were in California and six (19%) were in Oregon. Four free-text responses indicated that the choice of ear was determined by the trapper. The greatest proportion of ear tips were performed after sterilization (48%, n = 197/408), with 25% (n = 101/408) performed preoperatively, 20% (n = 83/408) performed intraoperatively and 7% (n = 27/408) at no set time.
Respondents (n = 399) reported use of a median of one method for excising the ear tip (IQR 1–2; range 1–5). A surgical blade was most commonly reported (85%, n = 341), and surgical scissors (36%, n = 143) or electrocautery (14%, n = 57) were also used frequently. All other methods were reported by <5% of respondents. Two respondents reported use of ear notchers noting that this method was standard in Hawaii. The majority of the 392 respondents who reported a preference preferred the surgical blade (69%, n = 271), followed by surgical scissors (17%, n = 67). However, only 157/399 (39%) respondents reported use of more than one method. Of those reporting at least two methods, 79% (n = 11/14) who had tried the wood-burning tool preferred it, 75% (n = 3/4) of those who had tried ear-cropping scissors preferred them, 59% (n = 84/143) who had tried a surgical blade preferred it and 36% (n = 41/113) who had tried surgical scissors preferred them.
The 404 responders characterized the amount of ear to remove from a full-grown cat variably. Respondents reported removal of 1 cm (36%), 6 mm (27%), one-quarter proportion of ear (21%), 1.25 cm (8%), one-third proportion of ear (6%) and other (2%). An example is shown in Figure 1.
(a) Photograph from a trap–neuter–return clinic showing measurement of the ear tip to be removed using a ruler marked with tape at 1 cm from the end. (b) Recommendations for the amount of ear tip to be removed demonstrated on a line drawing created by tracing the outline of the ear pinna and 1 cm measured line from photograph (a)
There was more consensus on the desired silhouette from the 374 respondents who replied, with 92% (n = 344) agreeing that straight across was preferred and 5% (n = 17) seeking a concave appearance (all others <5%). The location of the cut was nearly always guided by visual estimate (92%, n = 376/410), with an ear-tip template being employed 5% (n = 20/410) of the time. There was wide variation in the methods of hemostasis reported by the 366 respondents, with 23% (n = 83) using silver nitrate sticks, 18% (n = 65) commercial styptic gel, 16% (n = 58) styptic powder, 15% (n = 56) electrocautery, 11% (n = 41) hemostat alone and 8% (n = 29) compounded paste (all others <5%).
Complications
Ear tips were estimated to bleed after initial hemostasis in a median of 5% (IQR 2–10) of cats. There were no significant associations between the preferred method of excision (P = 0.144), characterization of the amount to remove (P = 0.637) or hemostasis method (P = 0.062) and breakthrough bleeding estimate. Negative feedback on the ear tip was estimated to occur a median of 1% of the time (IQR 0–5; range 0–60). There were no significant associations between negative feedback frequency and organization type (P = 0.289), excision method preference (P = 0.643) hemostasis method (P = 0.117) or characterization of excision amount (P = 0.510). In terms of weighted rank order (Figure 2), the most common feedback was that too much ear tip was removed (5.5), followed by a cat being ear tipped in error (4.7), persistent bleeding (4.2) and not enough tip removed (4.2). Less frequent was jagged (3.5) and infected (2.0) (Figure 2).
Stacked bar chart of rank of feedback (1–6) received regarding ear tips. Respondents could elect to not rank feedback that was estimated to never occur
Free-text response
Eighty-one (20%) of the 410 respondents shared a free-text response at the end of the survey. These responses were thematically grouped, with the following major themes identified.
Ear-tip variation
Eight respondents commented on the practical impact of ear tip variation regarding which ear to tip, desired silhouette and how much to remove. One respondent advised ear tipping ‘cats on the same side, regardless of sex’, and the reason for that as:
‘Working on large colonies in increments requires a lot of information input on how many cats remain to be altered. Camera work helps tremendously in this effort. It is often difficult enough to determine ear tips (angle of the camera vs angle of the cat’s head, etc). Tipping all cats on the same side takes out one more variable and makes camera placement easier.’
Another respondent explained:
‘Our protocol of tipping either ear on a cat came about to allow greater flexibility for our vet to quickly ear tip cats as they come out of surgery. It also allowed us the ability to work around damaged/wrinkled ears, or remove the tip of a white ear if a cat has white coloring. Several agencies in our area have TNR programs, and everyone uses a different method, so trying to stick to a certain sex getting ear tipped on a specific ear was moot with other cats in the area being ear tipped under different protocols. Bottom line, we found that simply conveying that the animal was sterilized was more important than trying to convey their sex.’
Further, one comment read: ‘Wish our community would agree upon which ear to tip!’ A respondent who identified as ‘a trapper of ferals’ wrote: ‘Notches are hard to determine when a cat is flailing about a trap’. Another respondent stated: ‘We prefer the ear tipping at the distal margin because the wedge version can look like old healed fight wounds’. One respondent noted ‘inconsistency of education/knowledge as to how much to take off, which causes disagreements among staff and outside groups’.
Ear-tip requirement and education
Several respondents advocated that TNR programs have clear policies requiring ear tipping and associated education as a way to reduce complaints from those bringing cats in to be sterilized. Thirteen noted that ear tipping is mandatory for their TNR programs. One commenter said that their program requires ‘statements explaining exactly what the ear tip is and what to expect and sign a document that they understand the cat will be ear tipped’. Another respondent stated: ‘usually once people understand the ear tips, there are little-to-no complaints’.
Ear-tipping method concerns
Additional concerns about trauma, pain and sterility were raised in the comments.
One respondent described their approach as: ‘We have worked very hard to ensure ears are not mutilated in the process. We do not lock hemostats but clamp briefly, cut and apply Kwik Stop/lidocaine. Cats do not seem to feel any pain/irritation post-ear tip’. Two respondents advocated dispensing with hemostats entirely. One comment read: ‘It can be really traumatic and is unnecessary. Using a thumb and forefinger to clamp down on the ear and then using clean, dull scissors does a great job of cauterizing the vessels as you cut’. Another described ‘cutting with just Mayo scissors and no hemostat is the best way to ear tip that I’ve seen. No bleeding and heals so nicely’. And yet another respondent addressed pain relief with ‘a small amount of lidocaine gel or cream prior to clamping/cutting. I’ve seen less ear-flicking and head-shaking since adding it to the protocol’. Sterility was of concern for another respondent: ‘I believe this procedure should be performed using sterile instruments, especially when retroviruses are prevalent. I see instruments for tipping put into “cold sterile“ (aka cold yuck) and immediately reused and think this is (a) significant concern’.
Adoptability
Five respondents commented on the adoptability of ear-tipped cats. One respondent stated:
‘We are being pressured by community TNR group to not ear tip friendly or semi-feral community cats because they feel it makes them less adoptable or they worry they have trapped a cat that might be owned if it’s friendly. We disagree because we feel it is best for the cat either way to not be trapped again.’
Another respondent wrote:
‘Often in areas where TNR grants are abundant, cats that are not feral or community owned are processed through these programs. At the time of surrender or rescue, these cats are easily turned away by shelters with the assumption that the cats belong outdoors and not at the shelter.’
Desire for best practices
Four commenters expressed interest in learning new and improved practices. One respondent ‘would like to know the Kwik Stop and betadine mixture and method’. Another said: ‘I need to learn more about the recommended protocol if there is one in terms of which ear, how much, etc, and if ear tipping and tattoos are both recommended’. And another: ‘would love to see follow-up research prospectively on ear-tip cautery procedures’. One respondent requested ‘a nice ear tip guide you can make or print out’.
Discussion
This survey revealed heterogeneity regarding ear-tipping practices within TNR programs in the USA. There were no significant associations between methods used and bleeding requiring additional hemostasis or negative feedback, so effectiveness could not be differentiated on that basis. Any method that fits the clinic situation in terms of personnel, available equipment and budget could be considered; estimated cost per cat analysis showed many inexpensive options (see Appendix 2 in the supplementary material).
The meaning of the ear tip should be clarified as many respondents reported it as an indicator of rabies vaccination and socialization status in addition to sterilization status. The ear tip is a binary marker indicating sterilization within a TNR program, 7 and nearly all of the survey respondents endorsed that meaning. Rabies vaccination may be a valid interpretation of an ear tip in communities where rabies vaccination is commonly performed in TNR programs, as one long-term TNR study showed a median age of 70.3 months for cats already sterilized and ear tipped at first visit, 17 which is within the rabies vaccination duration of immunity of 5–6 years demonstrated in dogs. 18 The ear tip is less reliable as an indicator of a cat’s socialization status, as this parameter can change over time, and sheltering organizations employ a variety of methods for assessment. 19 Survey respondents noted socialization and potential ownership status as factors in ear-tipping decisions, as well as concerns about the impact on adoptability in their communities.
The left ear was the most commonly tipped, but nearly 20% of respondents reported tipping the right ear or either ear. Consistency with the local standard for which ear to tip has been recommended as best practice. 3 However, some survey respondents reported conflicting standards within their local community. With national organizations now supporting TNR programs, the definition of ‘community’ may need to expand to a regional, state or national level.
The size of the ear tip was highly variable, and the most common complaint was that too much of the ear tip was removed. Few respondents used a measuring device, with 92% relying solely on visual estimation. Visual estimation has been shown to be highly variable in human medical settings, with the implication that more accurate measurement may improve outcomes.20,21 The desired outcome for an ear tip is clear visibility from a distance for population monitoring in a TNR program.6,7
Ear tips prevent unnecessary trapping and exploratory surgery. Per the respondents, 31% would pursue surgery even if there were other outward physical indications that a cat was already spayed. Unnecessary procedures are stressful and traumatic for the cats, as well as inefficient and costly for the TNR program. Ear tipping after the sterilization procedure ensures that a cat is not incorrectly marked if the procedure is not completed for any reason. Routine tattooing was performed on all cats in addition to ear tipping by the majority of respondents. As neutered male cats can be mistaken for females, ventral midline tattoos can prevent unnecessary surgery if the ear tip is not recognized. 3
Veterinarians performed the ear tip most commonly, but the procedure was also performed by non-veterinarians with varying degrees of formal education. Whether or not the ear-tipping procedure qualifies as veterinary practice must be referred to each state’s veterinary practice act. Specific provisions for animal shelters may be allowed provided that standards are established and followed.
Most respondents did not report use of multiple ear-tipping tools. Of those who reported use of more than one method, ear-cropping scissors and wood-burning tools showed the strongest preference. Hemostats were commonly used, but two respondents strongly advocated for eliminating the use of that instrument and using digital pressure only as described in the original publication within the veterinary literature. 1 Practitioners may wish to explore alternatives to their current practice if they are experiencing negative feedback regarding >1% of their ear tips, the median percentage reported in this survey.
Although this study did not ask about analgesia specifically, ear tipping should only take place under general anesthesia and include appropriate analgesia. Cats that undergo only tipping of the ear because they have already been sterilized should also receive analgesia. Some topical hemostatic agents may contain a local anesthetic agent such as benzocaine and lidocaine (as noted in Appendix 2) and may offer additional pain relief.
Based on the responses to this nationwide survey, establishment of a standard for ear-tipping practices would be helpful for both those performing this procedure and those interpreting the meaning of the ear tip and seeking to provide appropriate care for the cat. The ear tip is an important visual marker for community cat population control and essential for monitoring the success of a TNR program. The meaning and appearance of the ear tip must be clarified, as this procedure is now frequently performed in various practice settings by many types of organizations. The ear tip is a key part of the surgical procedure, and care and consideration should be taken with each patient.
Limitations
As this survey was distributed online via social media and email, the response rate cannot be calculated. Selection bias is likely due to distribution initially through organizations that promote TNR programs. Cross-posting was encouraged to reach a wider audience, so the ultimate distribution was unknown; responses may have been influenced by factors such as level of professionalism and specific organizational protocols. Owing to anonymity, multiple responses from one organization may have been received. The types of organizations presented in the survey were not clearly defined. Consequently, some areas of practice may have been under-represented, such as private practice veterinary partners for rescue organizations. Although individuals who completed <60% of the survey by abandoning it at Question 14 (the start of the methods questions) were excluded, some individuals who did not perform ear tipping themselves may have answered these questions affecting the accuracy of the methods responses. There may have been recall bias for the questions that required estimation of numbers and percentages, and the estimation rather than measurement of these complications would bias results toward the null. Initial hemostasis was not defined by an objective time period, which may have affected the estimated percentage of persistent ear-tip bleeding.
Conclusions
This survey revealed heterogeneity regarding ear-tipping practices in the USA. There were no significant associations between methods used and bleeding requiring additional hemostasis or negative feedback, so effectiveness could not be differentiated on that basis. Any method that fits the clinic situation in terms of personnel, available equipment and budget could be considered. Given the frequency and importance of this procedure, and the heterogeneity of responses, standards regarding the meaning and appearance of the ear tip would be helpful for both those performing it and those interpreting it in order to provide appropriate care for the cat.
Supplemental Material
Appendix 1
Survey questionnaire regarding ear-tipping practices for identification of cats sterilized via trap–neuter–return programs.
Supplemental Material
Appendix 2
Estimated cost per cat, in ascending order, for various reported ear–tip hemostasis methods.
Footnotes
Supplementary material
The following files are available online:
Conflict of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Ethical approval
This work did not involve the use of animals and therefore ethical approval was not specifically required for publication in JFMS.
Informed consent
This work did not involve the use of animals (including cadavers) and therefore informed consent was not required. No animals or people are identifiable within this publication, and therefore additional informed consent for publication was not required.
References
Supplementary Material
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