Obesity is a condition where the amount of body fat increases to the point that health and wellbeing starts to be affected. It is that second aspect that takes obesity beyond the cosmetic; it is a health concern not simply about how
either a person or a pet looks. Those of us in the veterinary world know all-too-well the many health problems that can arise in dogs and cats as a result
of this condition, including increased risk of developing arthritis, diabetes,
breathing problems, skin disease, and certain types of cancer.
By Alexander J. German BVSc, PhD, CertSAM, DipECVIM-CA, SFHEA, FRVCS
In a recent study of >50,000 pet dogs from 12 popular breeds, dogs that were in an overweight body condition (excess body fat) had a shorter lifespan than those with an ideal body condition. Although the impact varied amongst breeds, lifespan was most affected in dogs from the smallest breeds whose lives were 2.5y shorter on average. Such a reduction might not seem much for a person, but convert to ‘doggy years’, and that becomes substantial (the equivalent of 10-15 years less).
Besides these health issues, other studies have shown that quality of life is poorer in
dogs with obesity than those in ideal body condition and, over a lifetime, veterinary
costs are more making this a considerable burden on devoted pet owners. So much
so, there have been recent calls to classify obesity as a disease in dogs and cats, in
much the same way as for humans.
Recently, 23 national and international veterinary associations and allied organisations signed up to the Global Pet Obesity Initiative’s call to classify obesity as
a disease (https://petobesityprevention.org).
Classifying obesity as a disease is intended to be a positive step that both recognises the challenges faced by the owners of pets with the condition, but also encourages vets to be proactive and work in partnership with the owner in addressing it.
In the UK, the British Small Animal Veterinary Association (BSAVA) has gone one stage further by, for the first time developing and approving its own position statement on obesity www.bsava.com/Resources/Veterinary-resources/Position-statements/
Obesity). The statement aims to provide guidance to veterinarians about how to help
pets affected by the condition: as well as making a formal declaration that obesity is a disease, it recommends how to assess dogs and cats for obesity (using body conditions scoring), assist owners in helping dogs and cats to lose weight and to prevent obesity in dogs and cats that are at risk.
TALKING ABOUT OBESITY
A further reason for the BSAVA creating a position statement on obesity was to emphasise the need to rethink the way vets talk about this difficult medical condition, with a clear recommendation to ensure that any conversations with owners are supportive, non-judgemental, empathic, and use non-stigmatising terms.
‘Weight stigma’ is common across much of society including within the medical profession and, likely, also within the veterinary profession.
Such ‘disease stigmas’ arise when an individual is implicitly or explicitly blamed for
causing their own illness (with the implication being that they are immoral, unclean, or lazy).
Those in society that hold weight stigmatising views believe obesity in people to have arisen through laziness or overeating or both. The upshot is that people with obesity are subjected to prejudice and ridicule in many aspects of their life, and evidence suggests that it can negatively influence health whilst at the same time limiting their access to healthcare.
Although there has been little veterinary research on weight stigma, there is indirect evidence for its existence. For example, studies indicate that most vets believe ‘owner-related’ factors to be the main cause of pet obesity and will rarely discuss the topic when an owner of a cat or dog with obesity attends their practice. Of course, rather than the pet being considered responsible for his or her illness, it is the owner that is blamed for allowing it to occur. Weight stigma is further compounded when both owners (including children) and pets have obesity since, or so the opinion goes, this is suggested to be a failing of the family unit.
However, such attitudes are at odds with the considerable research that has been
undertaken on the causes of obesity in both people and pets. This is far from a simple disease to understand and is definitely NOT just the result of poor lifestyle or bad pet ownership.
In the authors’ opinion we will struggle to make progress in managing and preventing
obesity unless, first and foremost, we change our attitudes. Clearly, we have a long way to go, since history tells us that prejudices take years and generations to change. Therefore, I’m not expecting miracles here. Whilst the subject of obesity is clearly a difficult topic to talk about, if we could all make the effort to be more sensitive in the way we think about this condition, and how we discuss it, avoiding difficult words (such as ‘obese’ or ‘fat’), that would be a useful start. Such changes in the narrative might be enough to enable owners to speak more openly about the challenges that they face, and encourage them to seek help in improving the health and wellbeing of the pet.
WHAT CAUSES OBESITY IN DOGS AND CATS?
On the face of it, the obesity could be viewed as a simple problem of energy balance, namely consuming an amount of food (and therefore energy in the form of calories) in excess of that needed for normal bodily processes (‘metabolism’), warming and cooling the body, and physical activity. Given a fundamental law in physics (that “energy cannot be created or destroyed”), and energy that is surplus to requirements must be stored.
Adipose tissue (body fat) is the main energy storage organ, and so prolonged consumption of excess energy will lead to an increased volume and mass of fat. That’s where the simple explanation ends.In reality, it is far more complicated than that with many different factors influencing energy balance in many different ways. In dogs and
cats, these factors include:
- Genetic factors… genes that put the pet at risk of developing obesity. Recently Labrador retrievers (an obesity-prone breed) were found to carry a mutation in the pro opiomelanocortin (POMC) gene. This mutation is thought to affect behaviour and appetite of dogs, leading to weight gain.
However, whilst discovering the mutation is a start, it was only found in some dogs, and could not, on its own, explain all of the difference in bodyweight amongst dogs.
The genetic story is more advanced in people, where over 50 genes have now been identified that are associated with obesity.
Given the variety of breeds of dog, there are likely to be many more genes we still need to discover; clearly, we have a long way to go before we can truly discover the part that genetics plays in this story.
- Biological factors… such as age, whether the pet is neutered or not, digestion and absorption, the type of gut bacteria that is present, insulin production and glucose processing, and the production of various chemical (including inflammatory) factors produced by adipose tissue.
- Behavioural factors… including behaviours of both the pet (e.g. food-seeking behaviour, eating behaviour and physical activity) and owner (e.g. the bond they have with their pet, especially how they feed and exercise them).
- Environmental factors… including the living environment, type of food availability, opportunities to exercise, and the influence of others (e.g. friends, family and wider society). Regarding food, no one type of food has consistently been shown to be associated with obesity in either dogs or cats; however, ‘free-choice feeding’ (leaving food out for the pet to eat as much as it wants) and feeding extras (e.g. treats and table scraps) have both been consistently implicated.
Overall, it is interactions amongst these many factors that determine the relative ease, or otherwise with which a dog or cat will develop obesity. Furthermore, these factors interact with one another, often in unpredictable ways, and outcomes are often unexpected. Put another way, making a simple change to this system often doesn’t have the result that you expect. c
A classic historical example within the human health field was the fact that, in the 1970s, research suggested that fat (especially saturated fat) was the leading cause of heart disease and obesity. As a consequence, the health message that emerged was to eat low-fat foods but, despite this, the prevalence of obesity increased.
In recent times, the message has shifted away from restricting fat, to restricting carbohydrates and sugar. Although this shift has been more recent, the evidence available so far suggests that this approach will not address the problem of obesity.
In short, simple solutions do not work for obesity! Therefore, people who suggest that solving the pet obesity is simple, are mistaken. For example, either claiming pet obesity is just a failing of the owner or that obesity can be cured just by eating less and exercising more misunderstand the truly complex nature of this chronic disease.
CONSEQUENCES OF OBESITY IN DOGS AND CATS
As most will already be aware, obesity in humans has many health consequences including a greater chance of developing diseases such as diabetes, heart disease, metabolic syndrome, arthritis, breathing disorders, kidney diseases, and some kinds of cancer.
Overall, obese people have a greater risk of dying and tend to live a shorter lifespan. Various health concerns have also been identified in both dogs and cats. In dogs and cats, overweight and obese status is associated with a shorter median lifespan, poorer quality of life, various comorbidities (e.g. diseases that arise at the same time as obesity), metabolic irregularities (alterations in the body’s normal biochemical functions) such as insulin resistance and altered kidney function, and significant ‘functional impairment’ (where the function of the body’s organs are impaired, for example impaired breathing, impaired heart function, and impaired mobility).
WHY IS OBESITY ASSOCIATED WITH SO MANY CONSEQUENCES?
When there is too much fat present in the body, it can have negative consequences, which are both ‘mechanical’ and ‘biochemical’. Mechanical effects arise from the increased mass of body tissue and include increased loading of joints and bones, constriction/compression of the airways and lungs, compression of the urinary system, and interference with normal physical functions (e.g. grooming, walking etc).
The biochemical effects arise from the fact that adipose tissue produces numerous chemical signals (termed ‘adipokines’) that influence a diverse array of bodily functions. It is thought that, when an animal or person becomes obese, their adipose tissue becomes ‘hypoxic’ (i.e. the fat cells lack adequate oxygen) and then inflamed, which then affects the types and amounts of adipokines that are produced.
Many of the effects of obesity (including the development of other diseases are thought to arise from this alter adipokine profile. Thus, the aim of managing preexisting obesity (through weight reduction) or preventing it from arising in the first place are to rebalance reduce these biochemical abnormalities and improving overall metabolic health.
HOW IS OBESITY MEASURED IN DOGS AND CATS?
Body Condition Scoring (BCS) is the dog and cat equivalent of the human body mass index and can quickly be determined from a rapid assessment involving both a visual and a hands-on inspection. Although various systems exist, the BSAVA (and other international veterinary associations such as World Small Animal Veterinary Association [WSAVA]) recommend the use of a 9-point system. Scores of 4 and 5 out of 9 represent ideal weight, scores <4 suggest the pet is underweight, whilst scores from 6 to 9 suggest the pet is above ideal weight (‘overweight’ = 6 and 7; ‘obese’ = 8 and
9). Studies have shown that this system correlates well with the amount of fat in the body, as well as highlighting associations between increased BCS (≥6) and both a shortened lifespan and a greater risk of developing other illnesses.
Of course, BCS is not perfect and the main limitation is that, when the system was originally designed, 40% above ideal weight (corresponding to 9/9) was the extreme of
Sadly, we are seeing more and more dogs and cats that are ‘beyond the scale’, with many being 80%, 90%, or even >100% above ideal (twice their ideal weight).
In moving forward, there is a need to refine the system to take account of such patients.
A second limitation is that, although it is quick and easy to perform a BCS by a trained individual, owners tend to under-estimate the body condition of their own pet. Therefore, it is always advisable to contact your vet if you want to know what BCS your dog or cat currently is. That being said, owners can get a rough idea of the condition that their pet is currently in, with three simple checks:
- First, with your dog or cat standing (if possible), and using flat hands, run your hands up and down the sides of their body WITHOUT APPLYING ANY PRESSURE. Ask yourself honestly, whether or not you can feel the ribs. If you are struggling or having to apply pressure, the chances are that your pet is above its ideal weight.
- Next, with your dog or cat standing (if possible), look from the side. Ask yourself whether or not you can see a DISTINCT AND MARKED abdominal tuck i.e. the lower surface of your pet’s body (just behind the chest) should incline steeply upwards. (N.B.
If your pet has long hair, you might need to use a flat hand to trace this outline instead). If the inclination is more subtle, the tummy does not incline at all, or if the tummy bulges downwards, your pet is likely to be above its ideal weight.
- Finally, with your dog or cat standing (if possible), look from directly above. Ask yourself honestly, whether you can see a DISTINCT AND MARKED indentation inwards behind the chest i.e. you should ideally see an ‘hour-glass’ figure. (N.B. If your pet has long hair, you might need to use flat hands to trace this outline instead). If any indentation is more subtle, there is no indentation at all, or if the tummy bulges outwards, your pet is likely to be above its ideal weight.
One other simple thing an owner can do to monitor their pet is to weigh them regularly. Although measuring bodyweight is not as good as BCS at determining body fat mass, it is precise, accurate and very quick. Just like weighing yourself on bathroom scales, repeated bodyweight measurements over time can identify small changes that might highlight the fact that you are feeding your pet more than it needs.
Such regular measurements can be done by taking your pet to your vet practice regularly, since most will allow you to use their scales free of charge.
The added advantage is that your vet can record the weight in your pet’s medical record. If, however, visiting the vet is more challenging, you can keep track of your pet’s weight at home. Unless you have a very large dog, you can stand on your bathroom scales whilst holding your pet. Of course, don’t forget to subtract your own weight! Alternatively, if you have a small dog or cat, you could also weigh them using handheld luggage scales and a cat carrier. Again, don’t forget to subtract the weight of the empty box.
WHAT IF YOUR PET IS NOT CURRENTLY OVERWEIGHT?
What if your dog or cat is currently at ideal weight? Is everything fine? Sadly not. Many such pets can be at risk of developing obesity in the future if they have risk factors (see above) that put them at risk. The main challenge is that weight gain typically happens over a long time, such that daily changes are so slight they are imperceptible.
Therefore, prevention of obesity requires close monitoring of food and physical activity whilst, at the same time, monitoring the pet’s weight to ensure that there is no unexpected weight gain.
FOOD: The food to feed is a matter of choice for the owner, and many different approaches are now feasible. The PFMA has many fact sheets on animal nutrition and can serve as a good resource for guidance on food choice (www.pfma.org.uk/nutrition-facts).
Whatever you choose to feed your pet, I would strongly advise that you follow these three golden rules:
- Make sure it’s safe. This means that the food is unlikely to do any harm to your pet, family members or you. One example is if you choose to feed a food that is raw, since any bacteria will not be killed. Ensure that you take adequate hygienic precautions before and after handling it.
- Make sure it’s complete and balanced. Food that is complete and balanced will meet all ‘essential nutrient needs’, namely amino acids (the building blocks of proteins), vitamins, minerals, and essential fatty acids. Since the nutritional needs of cats and dogs vary, it is important to feed the food appropriate to the species.
- Make sure you don’t feed too much. This is my golden rule for obesity. Whatever food you choose to feed, there is a risk of weight gain if you don’t pay attention to how much your pet consumes. The best way of ensuring this is to start by feeding the recommended amount (usually displayed on the packaging), and weigh the food out as precisely as you can on electronic kitchen scales. This is because research has shown that other methods (such as using a measuring cup) are imprecise and tend to lead to overfeeding.
Once you know what you’re feeding you next need to weigh your pet to ensure that he or she is neither gaining nor losing weight. I suggest using a period of 2-4 weeks of stable weight as a guide. Congratulations you now know your pet’s daily food requirement!
Of course, remember that requirements can change in time, for example if their activity level changes or you switch to a different food, so you might need to check periodically. As a general guide, for an adult dog, it is recommended that bodyweight and BCS should be assessed at least every 6 months during the majority of adult life, but 3-monthly when older (as older dogs might start losing weight).
PHYSICAL ACTIVITY: Regular physical activity is good for both dogs and cats.
Dogs are best exercised with regular walks and interactive play sessions. For cats, the best approach is to encourage regular play sessions to stimulate exercise and movement. Always tailor the type of exercise to the individual. Controlled exercise (e.g. lead walking) is preferable if your dog has orthopaedic problems (e.g. arthritis etc). If walks are not possible for medical reasons, consider other forms of exercise e.g. swimming, hydrotherapy.
CAN WE PREVENT OBESITY IN THE FUTURE?
This is a great question, and the truthful answer is that I don’t know for sure.
However, I am confident that, if pet owners and vets work together we could probably do a better job than we are currently!
If we’re talking about prevention we need to start the job BEFORE obesity has a chance to develop.
Alarmingly, in one recent study, 21% of dogs under six months of age were already in overweight condition, findings that mirror the increasing prevalence of obesity in children. Why does this matter? Well other studies in people and pets have shown that those developing obesity early on (for example seven years of age for children) are at a much greater risk of having obesity for the rest of their life). So, if we want to do a better job on prevention, we need to start with new puppies and kittens!
The good news is that there are many ways that we can predict those pets that are at future risk of developing obesity and one key factor we should focus more on is how they grow. So, a possible prevention strategy of the future is for vets and owners to monitor bodyweight regularly during the first year or two of life.
Those of you who are parents will be aware of the ‘Red Book’ that accompanies your new child and that it includes a growth chart. This helps a health professional monitor how your child grows and to identify children that might not be growing properly.
The same charts can also identify children growing too quickly and, therefore, at future risk of obesity. Why am I telling you this? There are now similar growth charts which have been developed for puppies and (www.waltham.com/resources/puppy-growthcharts/) will hope to be a useful resource for use by owners and vet professionals in the future.
Current bodyweight can be compared with historical weight (for example an early-adult weight when the dog or cat was also recorded as being in ideal body condition), with deviations of 5% or more being flagged, and prompting. Such a strategy would highlight unwanted weight gain, which can be often addressed through adjustments to diet and exercise. The type of food fed is a matter of choice but should, ideally, be complete and balanced, appropriate for the life stage and lifestyle. The amount fed should be measured accurately (e.g. using electronic scales) and adjusted according to changes in bodyweight and BCS.
Obesity is a very common medical disease and now presents a major challenge to the health of our beloved pets. The condition is very complex with many factors contributing to the risk of a dog or cat gaining weight. The biggest challenge to the way we currently treat this disease is weight stigma, which means we often prefer not to discuss the topic or simply blame owners for the problem developing.
The good news is that when vets and owners work together for the benefit of the pet, quality of life can be improved. Finally, the authors main hope for the future is that we will all work together and do more to prevent this chronic disease.