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Dog and cat nutrition and obesity

Why is nutrition important?

Nutrition is complex and is fundamental to the healthy running of our pet's bodies. Incorrect nutrition can contribute to many health problems, e.g.: gastrointestinal disorders, skin diseases, heart disease, and dental disease.

It is important to have a healthy balance of vitamins and minerals, protein, carbohydrate, and fat. For this reason, we advise feeding good quality, complete pet diets which have undergone years of research to formulate ingredients that support your pet’s needs. Care should be given when feeding homemade diets, as these often will lack essential vitamins and minerals or have an imbalance of vitamins and minerals.

At different life stages, animals have different nutritional requirements, for example, puppies and kittens are growing; they, therefore, have a higher metabolic rate than older animals and require a higher amount of protein, digestible energy, and calcium than older animals.

Feeding a puppy food to an older dog or cat could cause the animal to become overweight and cause an imbalance in calcium/ phosphorus levels.

In dogs, it is important to choose an age-appropriate feed and a breed-appropriate feed, as there are different requirements for larger breed dogs compared to smaller breeds.

Are dog and cat foods the same?

Dogs and cats are not the same and have different dietary needs. Dogs are omnivores and, therefore, can consume a more varied diet, including both plant and animal-based ingredients. On the other hand, cats are true carnivores, meaning that they eat only animal proteins and have higher protein and fat requirements than dogs.

Cats require 11 essential amino acids to be provided by their diet, whereas dogs require ten amino acids. The other essential amino acid that cats need is taurine, which is only found in animal protein. Without sufficient insulin levels in their diet, they can develop impaired vision due to retinal degeneration and heart disease due to the heart muscles' weakening.

If cats were to eat dog food or human food for a prolonged period, they would, therefore, potentially become very sick. If dogs were to eat cat food for a prolonged period, the greater protein and fat contents of the cat food would likely exceed their nutritional requirements, making them likely to gain weight. It may also cause GI issues if a dog with GI sensitivity or prone to pancreatitis were to eat it.

It is therefore advisable that dogs and cats consume breed-specific diets.

General life stages and their requirements

Puppies and kittens

In both puppies and kittens, you are hoping to promote:healthy growth, joint and bone development.

For this you want a food that has:

  • High digestible energy- allowing energy requirements to be met without requiring large meals.
  • High levels of good quality protein to support growth and strong muscle development.
  • High but controlled calcium level support the development of strong bones and teeth. Too high a calcium level, especially in large breed dogs, can cause too-rapid growth and can be detrimental to their health, predisposing them to lameness issues in the future.
  • Healthy brain and eye development
  • Feeds must include a high amount of omega-three fatty acids to support eye and brain development.
  • Healthy skin and coat
  • Omega 6 fatty acids help to develop the skin's natural defences and natural oils and promote healthy skin and coat development.
  • Healthy digestion.
  • Fibre within the diet helps to maintain a healthy gut pH and digestive motility. This, as well as highly digestible energy and balanced protein levels, encourage healthy digestion.

Support immunity

Puppies are more vulnerable to diseases as they haven't yet developed natural immunity. Vitamins C and E can help to support immunity development.

Healthy urinary system

This is especially important in kittens as cats are prone to developing feline lower urinary tract disease. Diets should aim to maintain urinary pH between 6.2 and 6.4, and there should be a controlled level of magnesium and phosphorus to prevent crystal formation.


The aim of adult food is maintaining rather than building. Except for large breed dogs, other dogs and cats would have reached approximate adult weight and size, and their growth rate will have slowed. Continuing to feed puppy food to an adult dog could lead to obesity.

Adult feeds are slightly lower in digestible energy, calcium, and fat content than puppy foods. You want a feed that will promote a healthy coat and skin, healthy digestion, and support vital organs.

You, therefore, want a feed that includes:

  • A high level of good quality protein to support muscle health.
  • A balance of essential vitamins and minerals to support healthy organs, including a balance of calcium, magnesium and phosphorus to maintain a healthy urinary tract.
  • Omega 3 and 6, and essential fatty acids to maintain a healthy coat and skin.
  • Adequate fibre to provide dietary bulk, helping to maintain satiety and support healthy digestion. Sufficient fibre within the diet can also decrease diarrhoea incidence, and in cats can aid hair passage through the gut, reducing hairball formation. 'Light' or 'neutered' versions of diets often contain higher fibre and lower fat content than normal diets. This can make an animal feel fuller for longer and hence aids in preventing obesity/ aiding weight loss.
  • Antioxidants, including vitamin E, that helps to support a healthy immune system.

Mature and senior diets

These diets are aimed to help keep pets healthy for as long as possible in their later years of life.

The main difference in mature or senior diets is that they tend to be less calorific and have slightly lower protein levels to match the body's changing demands. As ageing animals (like humans), have a slower metabolic rate than younger animals, there is an increased risk of obesity if fed a normal diet. As our animal's age, it may also be that a vet recommends a prescription diet to help support specific organs and body systems.

When would I need a prescription diet?

Under certain circumstances, a specific diet might be advised. These diets should only be used after the recommendation of a vet.

Some of the most common reasons why a specific diet may be advised in adult animals may be:

  • Allergic skin disease thought to be due to food allergens- a specific flavour or hydrolysed diet may be advised.
  • IBD/ chronic gastroenteritis or colitis- a hypoallergenic/ hydrolysed diet may be suggested.
  • Pancreatitis- a low-fat diet may be advised.
  • Dental disease- an oral prescription diet may be advised, which has a larger kibble size to remove Plaque from the teeth on crunching.
  • Urinary diet- in dogs or cats prone to cystitis and or crystal formation, which maintains urinary pH and controls magnesium, phosphorus and calcium levels.
  • Metabolic or weight loss diet if struggling with an animal’s weight.

In senior/ older animals, some of the diets include:

  • Diabetic diets- which are lower in fat and calories, and higher in fibre, to slow food absorption and prevent spikes in blood sugar levels.
  • Heart diets- low in fat, calories and sodium.
  • Kidney diets- lower levels of phosphorus and lower levels of high- quality protein to help maintain the health of the kidneys.
  • Joint diets- contain glucosamine and chondroitin sulphate. Supplements can also help with joint disease.

Animals and obesity- why is it important, and what can you do to help prevent it?

In a pet obesity study in the UK in 2019, it was found that 51% of dogs and 44% of cats are clinically obese. This can have a hugely detrimental effect on pet health. It can:

  • Cause reduced mobility, leading to decreased activity levels and reducing the quality of life.
  • It can hasten the progression of osteoarthritis (OA) and worsen the clinical signs associated with OA due to carrying extra weight.
  • It can cause diabetes to develop (especially in cats)
  • It can cause or worsen heart disease.
  • It can cause or worsen respiratory issues and even lead to respiratory distress
  • It can cause high blood pressure.
  • It can encourage the development of some tumours, e.g. Lipomas.
  • Exercise and dietary management are fundamental to preventing obesity and keeping our pets healthy.

We tend to assess animals via body condition scoring. This looks at the animal’s fat distribution over all its body. The ideal body condition score is 2.5/5 or 5/9 (dependent on which scale/ system is used). At this body condition, the animal is well proportioned with ribs palpable with a slight fat covering, they have a visible waist behind the ribs when viewed from above and have a minimal abdominal fat pad.

Ways that you could reduce your animals’ weight if overweight:

  • Increase daily exercise.
  • Decrease dietary intake by 25%- be strict and consistent on what you feed, weighing out kibble daily.
  • Switch to a 'light' version of your animal’s usual diet
  • Restrain from giving fatty treats, instead give no treats, use a portion of their weighed out, daily allocated kibble to use as treats throughout the day or give low calorie treats such as carrot sticks or commercially available weight management treats.
  • Avoid feeding human food- dogs and cats have a lot lower daily calorie requirement than humans, and what may seem like a small treat to us, can equate to a large meal to our pets.
  • Trial weight management diets that help to increase your pet's metabolic rate.
  • Make use of and attend regular nurse weight clinics to allow us to help you and your pet on their weight loss journey and help tailor a plan that will suit both you and your animal.