Euthanasia in Horses - Bibliographic Review

EUTHANASIA IN HORSES # PART 1: A BIBLIOGRAPHIC REVIEW

New Zealand Equine Health Association

Following on from our paper on the practical aspects of euthanasia by Emma Gordon [Equine Euthanasia, EVP June 2022; 47(2): 41-43] we offer a discussion in two parts on the issues surrounding any decision for euthanasia. The first part is a bibliographic review given here, and the second part on page 59 is on reasons for, and considerations to have, at the time of a request or need for euthanasia.

“Euthanasia is available to the veterinarian when assisted death is believed to be in the best interests of the animals’ welfare relative to other practical options” (Yeates, 2010).

Utilising a welfare assessment tool can help with deciding whether a horses’ welfare or quality of life (QoL) is able to be improved or sustained at its current level or to inform a decision about euthanasia (Long, et al., 2022). The most up to date model of assessing animal welfare is the 2020 version of the five domains model where a person can consider a horse’s wellbeing according to these areas: 1. Nutrition 2. Physical environment 3. Health 4. Behavioural Interactions 5. Mental State The first three domains are known as the “survival-critical effects”, while domain 4 focusses on the animals’ interaction with the environment, non-human animals and humans; and domain 5 is the resulting animals’ perception in response to external circumstances (Mellor, et al., 2020). This model considers the positive and negative experiences that influence the horse’s wellbeing (Bell & Rogers, 2021). Often welfare models are used informally and are based on the knowledge and intuition of an experienced health professional and/or horse owner. Utilisation of objective and subjective measures and adjustment of criteria weightings allow welfare models to be tailored to individual cases (Long, et al., 2022). Whole animal indicators such as general attitude or a Qualitative Behaviour Assessment (QBA) can also be utilised, where indicators such as anxiousness, aggression or restfulness can indicate the horse’s general wellbeing (Long, et al., 2022). In a presentation given by Dr Kathleen Anderson at the Pan American Racing Conference (2017), she described a method for assessing the physical wellbeing of a horse using movement, eating, drinking and weight. These four aspects of wellbeing can be graded according to quality i.e. easy to move and good weight, through deteriorating, and to being unable to mobilise with poor condition (Anderson, 2017). Table 1 gives the decision-making guidelines for euthanasia that are recommended by Dr Anderson and contained in the AAEP guidelines.

Table 1: Considerations for euthanasia given by AAEP.

A horse should not have to endure the following: • Continuous or unmanageable pain from a condition that is chronic and incurable. • A medical condition or surgical procedure that has a poor prognosis for a good quality of life. • Continuous analgesic medication and/or box stall confinement for the relief of pain for the rest of its life. • An unmanageable medical or behavioral condition that renders it a hazard to itself or its handlers.

WHAT ARE THE REASONS FOR EUTHANASIA?

Research suggests that the majority of the time, horses are euthanised due to physical reasons, ‘old-age’ or age-related conditions (Bell & Rogers, 2021; Ireland, Clegg, McGowan, Platt, & Pinchbeck, 2011). Studies have reported laminitis related problems (25% of participants), colic (21%), and lameness (20-24%), age-related deterioration (20%) are the most common physical causes of euthanasia (Pollard, Wylie, Newton, & Verheyen, 2020; Ireland, Clegg, McGowan, Platt, & Pinchbeck, 2011). Having poor owner-perceived hoof quality further increased the rate of euthanasia. Research done by Bell & Rogers (2021) shown in Figure 1, shows that of the 211 horses included in the study, owners reported the majority were euthanised due to physical causes, except for 11 horses that were deemed to be ‘dangerous. This research was a questionnaire of people who had had a horse euthanised in the past, which revealed that colic, arthritis, and lameness (19% each), pain, old age, or general

quality of life (15%) were the main causes reported (Bell & Rogers, 2021). Colic is shown to be main cause in younger horses, as demonstrated in a euthanasia stress response study of 40 horses aged 6 to 24 years which revealed 16 horses were euthanised due to colic (Gehlen, Loschelder, Merle, & Walther, 2020). Another study of 55 horses admitted to hospital for colic symptoms 18 were euthanised: 4 during surgical intervention, 4 during medical management, 3 from catastrophic injuries in anaesthetic recovery, 2 following a second round of surgical intervention. The average age of these horses was of 13.6 years range (6-21 years) (Lightfoot, Burford, Bowen, & Freeman, 2021). Ireland, Clegg, McGowan, Platt & Pinchbeck (2011) described other factors which increased the risk of mortality in older horses included being underweight, increased clinical signs, and pain limiting normal daily activities. Age has a considerable influence with horses aged over 30 years are five times more likely to be euthanised than horses in the 15-19 years age group (Ireland, Clegg, McGowan, Platt, & Pinchbeck, 2011). Age related conditions such as Pituitary Pars Intermedia Dysfunction (PPID), diseases where age is a risk factor and declining immunity may contribute to mortality in geriatric horses (McFarlane & Holbrook 2008, Freeman & Schaeffer 2001, Garcia-Seco et al, 2005, cited in Ireland, Clegg, McGowan, Platt, & Pinchbeck (2011). It is understood that horses are more likely to be euthanised for Figure 1: Physical reasons for euthanasia. From Bell & Rogers, 2021.

physical reasons rather than issues relating to the horses’ affective state or behaviour although some horse owners may choose to euthanise due to dangerous behaviour (Bell & Rogers, 2021). There is a suggestion that dangerous or aggressive behaviour is linked to possible underlying physical issues. Aggression can be an indicator of pain and prolonged stress can lead to physical issues (Long, et al., 2022; Green, 2022). When humans’ safety is compromised, due to a horse that has become dangerous and/or the horse is no longer of “use” then euthanasia may be implemented (Green, 2022; Jones, 2022). Assessment of the horsemanship ability of an owner caring for a dangerous horse is important when considering euthanasia. Further, changes to a horse’s mental health may include depression and distress due to box rest or loss of a companion. Horses which are showing obvious signs of distress, with little or no improvement may be euthanised. Some abnormal behaviours such as crib biting, wind sucking or weaving have become normalised within the industry, associated with stabling/routine management, therefore owners often don’t recognise these behaviours as early indicators of pain, fear, and stress (Bell & Rogers, 2021). It is not unusual for two horses to be euthanised together to avoid a stressful experience for the horse left behind if an alternative suitable companion cannot be found (Jones, 2022). Euthanasia can be seen as a “positive welfare decision”

YOUR CHANCE TO WIN $150.00!

All you must do is write a clinical report that is published in the EVP, and your contribution may be eligible for one of several prizes of $150.00 that the EVP has available each year. The EVP Editorial Group wish to promote the sharing of your interesting cases and practice tips with the wider equine veterinary community, so please contribute. Every case, technique, test and interpretation are different, no matter how experienced we are or how routine the case is, so there is always something for us to learn from each other.

Take photos, dig out your diaries, get keyboard tapping and share your views with colleagues. You could be $150.00 richer for it! Please send your clinical reports to the EVP Editor for consideration.

Joe is happy chat with you about any articles or ideas you might have. Please contact Joe at evp.editor@gmail.com or on 027 437 3651.

in terms of being “able to end an animals’ suffering” and/or prevent a lifetime of suffering. Changes in an owners’ situation such as redundancy or illness may mean they are no longer able to care for a horse, this can be further complicated by horses that are not viable to be rehomed or sold e.g. horses that require high levels of care, months of box rest, expensive treatment (Green, 2022). Consideration needs to be taken of the horses’ future QoL (Long, et al., 2022). Where a horse has lost its utility i.e., able to be ridden, used for competition/ racing, a situation arises where the horse has insufficient value to justify the costs of upkeep (unless the horse has significant sentimental value). Some horses have an alternative use such as mares being used in the broodmare paddock. In one study, other factors influenced the rate of euthanasia including being a cross bred vs being pure bred which resulted in higher mortality rates on multivariate analysis in older horses (Ireland, Clegg, McGowan, Platt, & Pinchbeck, 2011). While the reasons for euthanasia quite clearly show the most probable cause is physical issues, the research available is limited to owner-reported data. The study conducted by Pollard et al (2020) included only horses with laminitis while Ireland et al (2011) included only horses over the age of 15 years. Further there is no NZ based research in this regard.

IMPLICATIONS OF DELAYED EUTHANASIA

It is important to consider the timeliness of euthanasia, with ethical and welfare implications to consider where euthanasia is delayed, particularly the prolonged suffering of the horse (Cameron, et al., 2022; Anderson, 2017). Reports suggest that people are reluctant to decide on implementing euthanasia for reasons including: “financial cost, emotional attachment, peer pressure, negative attitudes towards killing, poor recognition of pain and stress indicators” (Anderson, 2017; Bell & Rogers, 2021). A person may not be able to afford the cost of treatment required to sustain life, the cost of euthanasia or may not want to put the horse to sleep, leading to welfare being compromised (Jones, 2022; Lightfoot, Burford, Bowen, & Freeman, 2021; Jones, 2022). Studies have highlighted the concept of “responsibility guilt”- where a person feels guilty for putting a horse down (Clough, Roshier, England, Burford, & Freeman, 2021). Further it has been identified that some horse owners showed an inability to recognise pain or stress in horses leading to further delays in euthanasia. Consideration must also be given to the owners’ willingness and resources to continue intervention (Long, et al., 2022). It is not acceptable to allow a horse to die an emaciated death from natural causes (Anderson, 2017). Therefore, veterinarians must ensure that owners have a clear understanding of the options presented to them.

REFERENCES

Anderson, K. (2017). Compassionate considerations for end of life. Pan American Conference. Washington. Retrieved August 15, 2022, from https://www.youtube.com/ watch?v=tNAmp4tvWhA

Bell, C., & Rogers, S. (2021). Attitudes of the equestrian public towards equine end of life decisions. Animals, 11(6), 1176. Retrieved August 15, 2022, from https://www.ncbi. nlm.nih.gov/pmc/articles/PMC8232243 /

Cameron, A., Pollock, K., Wilson, E. et al. (2022). Scoping review of end-of-life decision making models used in dogs, and cats and equids. Vet Rec, 191(4). Retrieved August 22, 2022, from https://doi.org/10.1002/vetr.1730

Clough, H., Roshier, M., England, G., Burford, J., & Freeman, S. (2021). Qualitative study of the influence of horse-owner relationship during some key events within a horses lifetime. Vet Rec, 188(6). Retrieved August 22, 2022, from https://doi.org/10.1002/vetr .79

Gehlen, H., Loschelder, J., Merle, R., & Walther, M. (2020). Evaluation of stress responses under standard euthanasia protocol. Animals, 10(485), 2076 - 2615. doi: 10.3390

Green, S. (2022, April 14). Making an end of life decision for your horse: how to know when its time. (S. Green, Interviewer) Retrieved August 22, 2022, from https://www. youtube.com/watch?v=ZnnuWMmAfI8

Ireland, J. L., Clegg, P. D., McGowan, C. M., Platt, L., & Pinchbeck, G. L. (2011, Sept). Factors associated with mortality of geriatric horses in the United Kingdom. Prev Vet Med, 101(3-4), 204-218.

Jones, E. (2022). Horse and Hound. Retrieved from Better a week early than a day late: the hows and whens of equine euthanasia: Horse and Hound https://www. horseandhound.co.uk/news/better-a-week-early-than-a-daylate-the-hows-and-whens-of-equine-euthanasia-784923

Lightfoot, K. L., Burford, J. H., Bowen, I. M., & Freeman, S. L. (2021). Prospective study exploring factors assocaited with the euthanasia of horses referred for colic. Eq Vet Edu, 33, 46. Retrieved August 2022, 20

Long, M., Durnberger, C., Jenner, F. et al. (2022). Quality of Life within Horse Welfare Assessment Tools: Informing decisions for chronically ill and geriatric horses. Animals, 12(1822). doi: https://doi.org/10.3390/

Mellor, D. J., Beausoleil, N. J., Littlewood, K. E. et al. (2020). The 2020 Five Domains Model: Including humananimal interactions in assessments of animal welfare. Animals, 10(10). Retrieved August 30, 2022, from https:// doi.org/10.3390/ani10101870

Pollard, D., Wylie, C. E., Newton, J. R., & Verheyen, K. L. (2020). Factors associated with euthanasia in horses and ponies enrolled in a laminitis cohort study in Great Britain. Prev Vet Med, 174. Retrieved August 15, 2022, from https://www.sciencedirect.com/science/article/abs/pii/ S0167587719305720

Yeates, J.W. (2010), When to euthanase. Vet Rec, 166: 370-371. https://doi.org/10.1136/vr.c226

#Prepared for The NZ Equine Health Association by Tony Parsons (Equestrian Sport NZ) and Hillary Milne (NZEHA), with input from Ronan Costello (New Zealand Equine Veterinary Association), Tim Pearce (Equine Research Foundation) and Marty Burns (New Zealand Thoroughbred Racing).

NEW ZEALAND THOROUGHBRED RACING RACE DAY DATA

Indicator

Wagering on NZ Racing ($NZD) NZ Stakes ($NZD) NZ Race Days NZ Starts

Average Field Size Average Wagering per Race Day ($NZD) Average Stakes per Race Day ($NZD) Q3 2022 (Feb - Apr)

97,975,315

18,009,000

66

5,773

10.40

1,484,474

272,864

Q3 2021 (Feb - Apr)

96,142,457

15,307,500

65

5,649

10.16

1,479,115

235,500

% Change

1.91

17.65

1.54

2.20

2.36

0.36

15.87

Business Special Issue 2022 - EquiManagement

CONTENTS INCLUDES:

y Marketing New Services y Understanding Corporate Acquisition y Solo Practice Tips y Equine Telemedicine y When to Refer y Veterinarian Wellness

SPECIAL BUSINESS ISSUE THAT IS FREELY AVAILABLE HERE:

Also free access to EquiManagement Updates

Research Reports Disease Du Jour podcast Business of Practice podcast

https://equimanagement.com/page/newsletter https://equimanagement.com/disease-du-jour-podcast https://equimanagement.com/the-business-of-practice-podcast