Companion animals

Cat relaxing on couch
📷 Galyna Andrushko //

Companion animals are growing in numbers not only in the West but also in many Asian countries (e.g., China). In some respects companion animals receive special treatment (as compared with other animals used by us). In other respects, however, they suffer as a direct result of the way we use them. Some companion animals, for instance, develop health or behavioural problems caused by social and physical factors in their environment.

Our awareness of the importance of companion animals in many people's lives is growing; in fact such animals are frequently used for therapeutic purposes. At the same time, many companion animals are abandoned, given up to shelters, or euthanized. Companion animals thus seem to be viewed both as individuals to be respected in their own right and as disposable sources of enrichment for humans.

On this site you will find various publications about companion animal ethics and welfare within the categories listed below. The categories are sorted alphabetically.







Insect-repelling behaviour in horses in relation to insect prevalence and access to shelters

By JW Christensen, CG Strøm, K Nicová, CL de Gaillard, P Sandøe & H Skovgård (2022)
Applied Animal Behaviour Science. Elsevier


Pasture access is key to horse welfare, but during summer biting insects can cause discomfort and lead to health issues related to transmission of diseases and allergies. To measure the level of discomfort and whether access to shelters or other indoor areas may help prevent biting insect nuisance, we studied 39 horses: n = 21 with free indoor access (five groups) and n = 18 without indoor access (four groups) and recorded horse position (e.g., inside or outside), insect-repelling behaviour (e.g., tail swishing and head tossing), faeces cortisol metabolites, weather conditions, and insect prevalence through trap catches (e.g., tabanids which are known to attack horses). Data were collected one day per week per group for eight weeks during midsummer. Tail swishing (mean occurrence: 29.4 ± 1.1 per min) and skin shivering (mean occurrence: 13.8 ± 0.6 per min) were the most frequently recorded behaviours. The total frequency of insect-repelling behaviour was affected by treatment (indoor access vs. no access) and tabanid trap catches in interaction (F1281 = 8.08, P = 0.005), as more repelling behaviour was shown by horses without indoor access with increasing tabanid prevalence. Horses with indoor access were inside on 69% of recordings on days with a high tabanid prevalence vs. 14% on days with low tabanid prevalence. Concentrations of faeces cortisol metabolites did not differ between days with low vs. high tabanid prevalence. The following year, we conducted a small follow-up study on 13 horses (6 with free indoor access and 7 without) and recorded behaviour and saliva cortisol on four selected summer days with either low or high insect prevalence (2 ‘low’ and 2 ‘high’ days). On ‘high’ insect days, saliva cortisol increased significantly in horses without indoor access, suggesting that biting insect nuisance is reflected in saliva cortisol concentra- tions. We conclude that free access to shelters or other indoor areas during summer reduce nuisance by biting insects and thereby can improve horse welfare.

Insect-repelling behaviour in horses in relation to insect prevalence and access to shelters (URL)

Development and consistency of fearfulness in horses from foal to adult

By J. Winther Christensen, C. Beblein & J. Malmkvist (2020)
Applied Animal Behaviour Science. Elsevier


Understanding the development and consistency of behavioural responses across life stages is of both fundamental and applied interest. In horses, fearfulness is particularly important because fear reactions are a major cause of human-horse accidents, and because fear is a negative emotional state with negative consequences for animal welfare and performance. In this study, we investigated the development and consistency of fear reactions in horses, from foal to adult. Twenty-five warmblood stallions of the same age, kept under the same conditions and with minimal human handling, were tested in novel object tests before weaning from the dam (at 5 months) and after weaning, at 1 year (two tests) and again at 3.5 years of age (two tests). Behaviour and heart rate responses were recorded. We found that foals’ expression of alertness towards novel objects was the best predictor of their later behaviour. Some changes in the expression of fear-related behaviour were evident pre and post weaning. Consequently, there were stronger correlations between the post-weaning tests, although these were further separated in time (2.5 years) than the 5 months and 1-year tests (7–9 months). Further, there were positive correlations in the horses’ reactions in the two tests at 1 year and at 3 years (e.g. heart rate: rs = 0.82, P < 0.001 and alertness: rs = 0.68, P < 0.001), suggesting that fearfulness is relatively stable across test situations at a certain age point. We conclude that it is possible to test for fearfulness at an early age (before weaning), by measuring the level of alertness towards novel objects. However, responses in post-weaning tests are more consistent. Our findings contribute to an understanding of the expression, development and consistency of fearfulness, which is advantageous for early assessment of behavioural differences in horses.

Development and consistency of fearfulness in horses from foal to adult (pdf)














Estimating the Population of Unowned Free-Ranging Domestic Cats in Denmark Using a Combination of Questionnaires and GPS Tracking

Nielsen, H.B., Jensen, H.A., Meilby, H., Nielsen, S.S., & Sandøe, P. (2022).
Animals. MDPI

Simple summary

Unowned free-ranging domestic cats divide opinion. Some people object to them. They dislike the noise they cause and disapprove when they find their faeces in gardens and public places. Others are concerned about the cats’ welfare. It is widely believed that the number of unowned unsocialised cats (alleged to be 500,000) and additional unowned socialised cats in Denmark is huge. To assess whether this belief is correct, this study estimated the size of the population of unowned free-ranging domestic cats and their distribution in Denmark using a combination of questionnaires and GPS tracking. It was estimated that approximately 90,000 unowned cats are in the country, and that one-third are socialised and two-thirds unsocialised. It seems therefore that the number of free-ranging cats in Denmark that are unowned and unsocialised is only a fraction of that claimed, and that panic is unwarranted. The highest population density of unowned cats was found in rural areas.


The present study aimed (1) to estimate the size of the population of unowned free-ranging domestic cats in Denmark using a questionnaire survey combined with a GPS-tracking survey, and (2) to estimate the distribution of the population across different habitats. The questionnaires were circulated in 94 randomly selected parishes ranging across seven kinds of habitat. Using responses from five of the habitats, we estimated the population of unowned free-ranging cats nationally. In the other two habitats, questionnaire data were collected in a simpler way. The territory of 59 owned cats was estimated with GPS tracking to assess home ranges. Home range area was calculated using 95% Brownian bridge kernel density estimation (0.033–0.077 ± 0.011–0.023 km2, median ± SE). We estimated a population of unowned free-ranging cats in Denmark of 89,000 ± 11,000 (SE), with a mean density of 2 ± 0.3 (SE) cats per km2, living primarily in rural habitats. Approximately one-third of the cats were estimated to be socialised and two-thirds unsocialised. Our method may be suitable for use in other temperate areas facing problems with unowned free-ranging cats.

Estimating the Population of Unowned Free-Ranging Domestic Cats in Denmark Using a Combination of Questionnaires and GPS Tracking (URL)

How Serious Are Health-Related Welfare Problems in Unowned Unsocialised Domestic Cats? A Study from Denmark Based on 598 Necropsies

Thuesen, I. S., Agerholm, J. S., Mejer, H., Nielsen, S. S., & Sandøe, P. (2022)

Simple summary

Domestic cats are very popular companion animals, but a significant number are ownerless. These are either socialised or unsocialised. The former can be re-homed. Unsocialised domestic cats, on the other hand, are difficult to handle and fear humans. Therefore, rehoming them is challenging. Unowned unsocialised cats are seen by many people as a nuisance, a hazard to human and animal health, and a threat to biodiversity. However, others have concerns about their welfare, although our knowledge of how well these cats actually cope is very limited. To remedy this, we studied the corpses of 598 unsocialised cats euthanised in Denmark in 2019 by two cat welfare organisations. Our findings reveal that unsocialised cats in Denmark face only a moderate load of health-related welfare problems, even in comparison with owned cats. So, although there may be other reasons to euthanise unsocialised cats, this practice may, in a place like Denmark, be difficult to justify by pointing to the welfare needs of the cats.


Free ranging unsocialised domestic cats are widely believed to suffer from a high load of welfare problems. We assessed the validity of this belief by performing necropsies on the corpses of 598 unsocialised cats, originating from all parts of Denmark, that had been euthanised by two Danish cat welfare organisations. We selected a number of variables for health-related cat welfare that could be assessed through necropsy (e.g., gross lesions, ectoparasites and body condition) or by laboratory analysis (e.g., infection with feline immunodeficiency virus (FIV), and by feline leukaemia virus (FeLV)). Each finding was classified as having either a major or minor welfare impact on the cat. More than 83% of the cats had no major finding, and 54% had no finding indicating a welfare issue at all. More than 83% of the cats had a body condition within normal range. Only 0.3% were emaciated. The most common finding was infestation with ectoparasites, with 15.9% infected with lice, 12.3% with fleas, 4.7% with ticks, and 6.7% with ear mites. FIV and FeLV were detected in 9.2% and 1.2% of the cases, respectively. The most common lesion related to the cats’ teeth. Overall, unsocialised cats in Denmark have a moderate level of health-related welfare problems.

How Serious Are Health-Related Welfare Problems in Unowned Unsocialised Domestic Cats? A Study from Denmark Based on 598 Necropsies (URL)

Owner-related reasons matter more than behavioural problems - a study of why owners relinquished dogs and cats to a Danish animal shelter from 1996 to 2017

By  J. B. H. Jensen, P. Sandøe & S. S. Nielsen (2020)
Animals. MDPI


Every year, dogs and cats are relinquished to animal shelters by their owners in large numbers. Reasons for relinquishment of dogs and cats to a large Danish shelter from 1996 to 2017 were obtained and characterised. The reasons were available for 86% of the owner-relinquished animals, including 3204 dog relinquishments (90%) and 2755 cat relinquishments (82%). They were allocated to 59 categories, which were further merged into four owner-related and three animal-related reasons. The most commonly reported of these seven reasons for relinquishment of dogs were owner health (29%), animal behavioural problems (23%), housing issues (21%) and lack of time (14%). For cats, the figures were: owner health (32%), housing issues (26%), and animal behavioural problems (25%). No systematic changes in these patterns were found over time. The number of relinquished cats was roughly stable, whereas the number of relinquished dogs decreased on average by 3% per annum. Owner issues were the primary reason for relinquishment in both species, but nearly one-quarter of the animals were relinquished as a result of behavioural problems. As the latter are often connected with the owner in some way, the results emphasise the importance of a focus on owners when addressing pet relinquishment challenges.

Owner-related reasons matter more than behavioural problems (pdf)

Shelters Reflect but Cannot Solve Underlying Problems with Relinquished and Stray Animals—A Retrospective Study of Dogs and Cats Entering and Leaving Shelters in Denmark from 2004 to 2017

By P. Sandøe, J. B. Jensen, F. Jensen & S. S. Nielsen (2019) 


Data covering about 90% of the estimated intake of dogs and cats to Danish shelters from 2004 to 2017 were used to study the effects of tight control of dogs and of efforts to increase shelter services for unwanted or stray cats. During the period, there was a low and decreasing intake of dogs, while the annual proportion of euthanised dogs increased from 6% to 10%. The number of cats entering shelters increased by about 250%, while the annual proportion of euthanised cats increased from 15% to about 29%. At the same time, there seemed to be a decrease in the population of stray cats. The major increase in cat intake may be due to animal protection non-governmental organizations (NGOs) making it easier to relinquish cats into shelters. Dog shelters can successfully handle surplus animals because dogs are well controlled by owners and are tightly regulated. Cats are more difficult to confine, are often allowed to roam freely and are less regulated. Therefore, cat shelters cannot solve the problem of surplus cats on their own. It is argued that an economic analysis may serve as a point of departure for a discussion on better policy making for NGOs in charge of shelters.

Shelters Reflect but Cannot Solve Underlying Problems (pdf)





Digital opportunities to connect and complain – the use of Facebook in small animal practice

Springer, S., Lund, T. B., Sandøe, P., Corr, S. A., Kristensen, A. T., & Grimm, H. (2022) 
VetRecord Open. 
British Veterinary Association



Social media is increasingly used in small animal practice, enabling veterinarians to connect with clients and promote their business online. It can also be used by clients to quickly distribute complaints via online communities.


Using a questionnaire study we investigated Austrian, Danish and UK veterinarians’ attitudes towards Facebook, the contents of clients’ online complaints and how they were handled by veterinarians (N = 648).


In Denmark and the UK, around 90% of practices had a Facebook page, in contrast to 40% of Austrian practices. Most Danish and UK veterinarians agreed that the use of Facebook was relevant and expected by clients. Agreement was lower among Austrian veterinarians, probably reflecting the lower uptake of social media there. In particular, younger veterinarians and those who actively used Facebook for the practice, could see benefits. In all three countries, we found that clients most frequently complained about treatment costs. Most veterinarians preferred to actively deal with clients’ complaints, either replying online or discussing them directly.


We recommend future research focusing on veterinarians’ personal use of social media and on clients’ use of and attitudes towards social media in the veterinary context.

Digital opportunities to connect and complain – the use of Facebook in small animal practice (URL)

Comparing veterinarians’ attitudes to and the potential influence of pet health insurance in Austria, Denmark and the UK

By S. Springer, T. B. Lund, H. Grimm, A.T. Kristensen, S. A. Corr & P. Sandøe (2022). 
VetRecord. BVA



Health insurance offers many benefits to clients and veterinarians, such as the ability to perform necessary and possibly cost-intensive medical interventions without financial constraints, or to potentially prevent euthanasia based on financial challenges. However, concerns about negative consequences, such as the overuse of diagnostic tests or overtreatment, have also been raised.


Using an online questionnaire distributed via e-mail, which included a section on health insurance, we investigated the relative number of insured dogs and cats treated by Austrian, Danish and UK veterinarians (N = 636) and the attitudes of those veterinarians toward health insurance. Further, using a case vignette, we examined whether coverage by health insurance may influence treatment suggestions.


Even though veterinarians in all three countries believe that health insurance reduces stress since clients’ financial resources will be less important, we found that Austrian veterinarians are more likely to agree that health insurance is unnecessary compared to Danish and UK veterinarians. Further, many raised the concern that insurance policies influence clinical decisions; and less than half supported the idea of making insurance mandatory. A majority of veterinarians in Austria and the UK thought that insurance can lead to the overuse of diagnostic tests, and in the UK a majority also thought that it can lead to overtreatment. Using case vignettes, we found that veterinarians were significantly more likely to suggest a CT scan to a client with an insured animal, in contrast to a client with stated financial limitations. Further, UK veterinarians were more likely to suggest a CT scan to a client with an insured animal, in contrast to a client without insurance.


In conclusion, we found that veterinarians, in general, were in favour of health insurance, and that greater coverage may increase more cost-intensive veterinary care. Our findings also raise a potential ethical challenge of health insurance causing differential access to clinical care for patients.

Comparing veterinarians’ attitudes to and the potential influence of pet health insurance in Austria, Denmark and the UK (URL)

“Patients’ interests first, but . . . ” – Austrian Veterinarians’ Attitudes to Moral Challenges in Modern Small Animal Practice

By S. Springer, P. Sandøe, T. B. Lund & H. Grimm (2019) 


Small veterinary practice is experiencing steady improvement in diagnostics and therapies which enable veterinarians to offer evermore advanced medical care for their patients. This focus group study of veterinarians (n = 32) examined the impact of these improvements and the potential challenges they introduce in small animal practice. It shows that while advanced diagnostics and therapies deliver benefits in patient care, they also add complexities to decision-making. Although the veterinarians participating in the study were aware of their duty to act in the best interests of the animal, their decisions were highly dependent on factors such as the client’s financial background and the emotional bond between client and animal, as well as the veterinarian’s place of work, and level and field of specialization, and certain economic aspects of the practice. The overall conclusion is that small animal veterinarians are increasingly torn between serving the best interests of the animal, medical feasibility and contextual factors related to the client, the veterinarian, and professional colleagues. Further, the findings suggest that services are not only oriented towards the provision of medical care in a strict medical sense. On top of this, veterinarians need to deal with various expectations and wishes of clients which influence their decision-making. As it will be shown, factors like the possibility of referring patients to specialist veterinarians or prompt diagnostic results influence their decision-making.

Austrian Veterinarians’ Attitudes to Moral Challenges in Modern Small Animal Practice (URL)

The veterinarian's dilemma: a study of how Danish small animal practitioners handle financially limited clients

By S. V. Kondrup, K. P. Anhøj, C. Rødsgaard-Rosenbeck, T. B. Lund, M. H. Nissen, & P. Sandøe (2016) 
Veterinary Record. BMJ Publishing Group


This study examined the extent to which Danish veterinary practices encounter financially limited clients and how different factors relating to the animal, the client and the veterinarian affect decisions to provide treatment for these clients. 300 small animal practices were invited to participate in an online survey. 195 participated, giving a response rate of 65 per cent. The results show that Danish small animal veterinary practices encounter clients with limited finances regularly: 33.8 per cent of them 3–4 times, 24.6 per cent 5–10 times and 19.5 per cent 1–2 times a month. Only around 9 per cent reported having a written practice policy on handling financially limited clients. Factors affecting decisions to treat include the severity and type of the animal’s condition, the medical care needed and the client’s expressed emotions. The propensity to treat is significantly higher in female veterinarians and in situations involving unborn animals. The overall conclusion is that small animal veterinary practices often provide treatment to clients who are not able to pay—far beyond what is legally required. This can be considered a major economic and psychological challenge for the practising veterinarians.

A study of how Danish small animal practitioners handle financially limited clients (pdf)

Veterinarians’ role in clients’ decision-making regarding seriously ill companion animal patients

S.B. Christiansen, A.T. Kristensen, J. Lassen & P. Sandøe (2016) 
Acta Veterinaria Scandinavica.
BioMed Central


Background - When companion animals become seriously ill clients may have doubts about treatment choices, if any, and turn to veterinarians for help. But how should veterinarians reply? Influence on clients’ decision-making may or may not be acceptable—depending on one’s attitude to principles such as ‘paternalism’, ‘respect for autonomy’ and ‘shared decision-making’. This study takes as a starting point a situation where the animal is chronically ill, or aged, with potentially reduced animal welfare and client quality of life, and thus where clients need to consider treatment options or euthanasia. It is assumed throughout that both veterinarians and clients have the animals’ best interest at heart. The purpose of the study was to explore the challenges these situations hold and to investigate how clients experience veterinary influence. A second aim was to reflect on the ethical implications of the role of veterinarians in these situations. Qualitative interviews were conducted with 12 dog owners considering treatment or euthanasia of their chronically ill or aged dogs.

Results - Challenges relating to the dog and to the client were identified. Some situations left the interviewees hesitant, e.g. if lacking a clear cut-off point, the dog appeared normal, the interviewee felt uncertain about treatments or animal welfare, or experienced conflicting concerns. Some interviewees found that veterinarians could influence their decisions. Such influence was received in different ways by the interviewees. Some interviewees wanted active involvement of the veterinarian in the decision-making process, and this may challenge a veterinarian’s wish to respect client autonomy.

Conclusions - Different preferences are likely to exist amongst both veterinarians and clients about veterinary involvement in clients’ decision-making, and such preferences may vary according to the situation. It is suggested, that one way to handle this challenge is to include respect for client preference on veterinary involvement under a wider understanding of respect for autonomy, and to apply models of shared decision-making to veterinary practice. In any case there is a need to further explore the challenges these situations raise, and for the veterinary profession to engage in more formal and structured deliberation over the role of veterinarians in relation to clients’ decision-making.

Veterinarians’ role in clients’ decision-making regarding seriously ill companion animal patients (URL)

Looking After Chronically III Dogs: Impacts on the Caregiver's Life

S.B. Christiansen, A.T. Kristensen, P. Sandøe & J. Lassen (2013) 
Taylor & Francis


Studies in human medicine show that care of chronically ill family members can affect the caregiver's life in several ways and cause “caregiver burden.” Companion animals are offered increasingly advanced veterinary treatments, sometimes involving home care. Owners choosing such treatments could thus face similar challenges when caring for their animals. This qualitative study uncovers impacts on an owner's life, when attending to the care of an aged or chronically ill dog and reflects on the differing roles of caregivers with animal and human patients. Twelve dog owners were selected for in-depth interviews based on the dogs' diagnoses, and the choice of treatments and care expected to affect the owner's life. Interviews were recorded, transcribed, and analyzed qualitatively. The dog owners reported several changes in their lives due to their dog's condition: practicalities like extra care, changes in use of the home, and restrictions relating to work, social life, and finances. These were time-consuming, tough, and annoying, but could often be dealt with through planning and prioritizing. Changes in the human–dog relationship and activities caused sadness and frustration, which in turn led to feelings of guilt, and in some cases created a feeling of loss. Also, concerns about the progress of the dog's condition, it's welfare, and euthanasia brought emotional distress and many doubts. The owners did, however, respond to the changes differently and as a result experienced different effects on their own life. This study confirms that the situations of caregivers with human and animal patients are in some ways similar, yet the study also identifies and reflects on some of the differences. These include the caregiver role and the options of assistance as well as euthanasia. Veterinary staff are urged to inform owners about possible impacts on their lives when considering careconsuming treatments, and to be aware of the need for support during treatment as well as in decisions about euthanasia.

Looking After Chronically Ill Dogs (limited access)