The risks for overweight pets
We know the rate of obesity in humans has been slowly increasing as research tells us it has close to doubled between 1980 and 2008. Unfortunately, as the rate of obesity in humans has steadily increased, so has the rate of obesity in dogs and cats. This is suspected to be partly due to change in lifestyle of both humans and animals. Now with animals being more a part of the family, they tend to live inside and as a result don’t have to compete for food. Owners have also become much more accustomed to treating their furry friends like humans or family members.
There are a number of well recognised risk factors associated with the development of obesity and an overweight state, which include: breed, age, gender and neuter status (hormonal influence), presence of endocrine disorders (eg, hyperthyroidism, hyperadrenocorticism), medications that results in polyphagia (eg, anticonvulsants, glucocorticoids), and poor nutrition and feeding habits.
Obesity has a number of implications on the health of our pets. The adipose tissue is a functional organ, which produces a number of hormones (eg, leptin, adiponectin) and inflammatory cytokines, which puts overweight and obese patients in a state of chronic inflammation. Leptin and adiponectin in particular are associated with insulin sensitivity in the body.
A study in paired Labrador retrievers that were either fed a higher calorie diet, or fed 25 per cent less than their counterpart, showed that the lean dogs have a significant increase in their median life span of almost 2.5 years. Leaner dogs also had a significant delay in the onset of clinical signs of chronic diseases, such as osteoarthritis, compared to their overweight and obese counterparts. Overweight and obese dogs and cats have a significant stress placed on their body, and the effects are felt in every body system.
With a greater amount of adipose tissue in the body, in particular abdominal or visceral adipose tissue, there is a larger amount of leptin secreted, and a lower amount of adiponectin, both of which have the effect of inducing a state of insulin resistance. This state has two main problems, the first of which is that the patient becomes hyperglycaemic and the pancreatic beta islet cells are stimulated to release more and more insulin. With time, this makes animals vulnerable to the development of type 2 diabetes, as well as hepatic lipidosis. Diabetes mellitus occurs much more commonly in obese cats and, though possible, is fairly rare in obese dogs.
Overweight cats have twice the risk of developing diabetes than lean cats, whereas obese cats have almost 4 times the risk of developing diabetes. Additionally, with every 1kg of weight gain above ideal in cats, leads to a 30 percent reduction in insulin sensitivity. The second problem with insulin resistance is the inability of the glucose to penetrate the satiety centres in the brain to signal to the patient that they are full and should stop eating. Therefore, the patient wants to keep eating, contributing to the problem of obesity.
Overweight states and obesity contribute to musculoskeletal diseases, such as ruptured cruciate ligaments and the onset of osteoarthritis.
Cruciate ligament rupture can be traumatic, but it is also attributed to repetitive load bearing. In a patient who is overweight or obese, the load that the joint and cruciate ligaments sustain is much higher, predisposing them to rupture.
Osteoarthritis onset occurs earlier in obese dogs, and this is attributed to obesity causing body-wide chronic inflammation. These inflammatory mediators can target joints, including non- or minimally-weight-bearing joints.
High blood pressure can develop in dogs and cats that are overweight and obese, but the pathogenesis is complex and may have contributing factors from changes in the metabolism of cholesterol, triglycerides and lipoproteins, as well as changes in the renin-angiotensin-aldosterone system and fluid overload, and increased peripheral vascular resistance due to the numerous cytokines, adipokines, sympathetic nervous system dysfunction and endothelial dysfunction.
The impacts of obesity in dogs and cats are wide reaching, affecting every body system and this highlights the importance of maintaining a lean body condition from juvenile years to adulthood.
If you’re concerned about your pet’s weight, contact your local Greencross Vets
to make an appointment for a free weight assessment.