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  • Writer's pictureDr Matt Kopke

Obesity and associated diseases in pets

Recently, we looked at how to body condition score dogs and cats. Given that it’s pet obesity awareness month, it seems only fitting to talk a bit more about obesity in pets. We’ll discuss the risk factors for obesity in cats and dogs, along with some of the diseases obesity is associated with.

The expanding problem of pet obesity

Obesity is becoming increasingly prevalent around the world in humans and in pets. The two, unfortunately, go hand-in-hand, it would seem, at least with dogs, as some recent studies have shown that owner obesity is an important factor for their dogs to end up being overweight or obese. In a study by Linder et al., the authors identified a positive correlation between owner's body mass index (or BMI) and the body condition score of their dog.

Another study by Saurez et al. had similar findings, concluding that being an overweight dog owner was the most important factor in the occurrence of obesity in dogs. A European study also reported that dog owners who do not consider obesity to be a disease are more likely to have obese dogs.

How prevalent is obesity in pets?

The prevalence of overweight or obesity ranges from between approximately 20-60% in dogs, and 10-50% in cats, depending on the region studied, with more recent studies, as is the case with humans, showing an increase in such numbers over recent years.

So, what are some of the other risk factors associated with weight gain in pets?

Broadly speaking, we can lump risk factors into the following headings:

  • Animal factors

  • Owner factors

  • Environmental factors

As I mentioned before, the most important risk factor for weight gain or obesity, in dogs at least, is the owner or pet parent being overweight.

Let’s start with animal factors.

Genetic risk (in other words, due to underlying genetic mutations) has been identified in Labradors and golden retrievers, along with Manx and domestic shorthaired cats.

Other factors include gender, neutering status, and middle age. Middle-aged neutered female dogs are more likely to be overweight or obese, and middle-aged neutered male cats are most likely to be overweight or obese.

Neutering status has long been known to be a risk factor for weight gain and subsequent obesity. This is due to a combination of decreased energy requirements following neutering, along with an increase in food consumption. While gonadectomy, or neutering, has been associated with a greater risk of being overweight, this risk is not influenced by the age at which neutering is performed.

Interestingly, changes in gut microbiota and the production of short-chain fatty acids have recently been identified as being involved in or part of the process of canine obesity after neutering. Clear negative correlations were found between short-chain fatty acid-producing bacteria and body weight, triglycerides, and HDL-C. What this means is that intervention with SCFAs-producing bacteria might represent a new target for the prevention or treatment of canine obesity after neutering.

Next up, owner factors.

We’ve already touched on the most important one of these, namely, owner obesity, but there are still others to consider. Owner household income and exercise habits are among the other risk factors that have been identified.

Lastly, environmental factors. Amount of physical activity, as is the case in humans, is a risk factor for weight gain. In dogs, reduced daily exercise has been associated with obesity, whereas in cats, limited or no outdoor activity has been linked to obesity.

Diet and nutrition, obviously, also play a huge role in overweight and obesity in both people and pets. In dogs, high-fat diets are associated with overweight or obesity in dogs. Similarly, in cats, high dietary fat, but not carbohydrate, induces weight gain and a concurrent increase in insulin, and neutering increases sensitivity to weight gain induced by dietary fat.

What diseases are associated with pets being overweight or obese?

There are certain obesity-related comorbidities that are shared between pets and people. Obesity is a major risk factor for the development of type 2 diabetes mellitus in people and in cats, but such an association hasn’t been identified in dogs, although obesity does affect diabetic control in dogs with diabetes. Obesity has also been associated with an increased risk for a number of human cancers (particularly those involving the endometrium (part of the uterus), colon, and pancreas). Various mechanisms underlying this increased risk have been proposed, with increased insulin levels being one of them.

While the studies in veterinary medicine are a bit more limited in this regard, there have been associations identified between obesity and cancer development in pets, with an example being canine mammary cancer.

Unfortunately, the list doesn’t end there. Other disease processes associated with obesity include:

  • Arthritis

  • Endocrine dysfunction – specifically, hypothyroidism, and hyperadrenocorticism – although the link here is likely causal rather than ‘associated’

  • Cruciate ligament rupture

  • Lower urinary tract disease – for example, an increased prevalence of asymptomatic (or non-clinical) bacteriuria has been identified in morbidly obese dogs

  • Oral disease

  • Pancreatitis

In addition to the above, other things to consider include:

  • Increased anaesthetic risk – this is likely due to a combination of respiratory dysfunction, altered renal function, and changes in cardiovascular parameters

  • Reduced quality of life – a study by German et al. showed lower vitality and higher emotional disturbance scores in obese dogs, with demonstrable improvement in these parameters following successful weight loss

  • Reduced lifespan – Salt et al. demonstrated a shorter lifespan in overweight compared with normal-weight dogs, ranging from between 5 months to 2.5 years in the breeds that they looked at, with the biggest difference reported in Yorkshire terriers and the smallest impact noted in German shepherd dogs

Are there any benefits to being overweight or obese?

While this will hopefully not be the take-home message of this talk, it is worth mentioning that in some contexts, it’s not all doom and gloom when it comes to pets being a bit chonky. This benefit is often referred to as an obesity paradox, and has been identified in both cats and dogs. Take cats with congestive heart failure as an example – cats with low body weights had shorter survival times compared to cats with moderate or high body weights. While being overweight or even mildly obese appears to have a protective effect once heart failure is present (when compared with low body weights), it is important to point out that cats with the highest weights, in other words, those that are morbidly obese, tend to have the shortest survival times, the same as those with low body weights.

Thanks for watching, and if you’re keen to see more content like this, including some tips and tricks on how to get that stubborn weight off your furry friend, please watch this space and subscribe.

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