Learning objectives: Define the size categories used throughout the course; identify the physiological differences that affect feeding; recognise breed-specific dietary considerations.

The size problem

Walk into any pet shop and you’ll see shelves of dog food. Most of it is marketed at “dogs” as a single category, with maybe a small-breed variant on the same shelf. This is misleading. A 4 kg Chihuahua and a 40 kg Labrador are more physiologically different from each other than a human is from a chimpanzee. Feeding them the same way — even proportionally — produces very different outcomes.

Throughout this course we’ll use the following size categories:

Category	Adult Weight	Examples	Typical Lifespan
Toy	Under 5 kg	Chihuahua, Pomeranian, Toy Poodle, Yorkshire Terrier	13–18 years
Small	5–10 kg	Cavalier King Charles Spaniel, Jack Russell, Shih Tzu, Mini Schnauzer, Mini Dachshund	12–16 years
Medium-small	10–15 kg	Beagle, Cocker Spaniel, French Bulldog, Whippet	11–15 years
Medium	15–25 kg	Border Collie, Australian Cattle Dog, Staffordshire Bull Terrier, English Bulldog, Springer Spaniel	10–14 years

If you’re working with a dog over 25 kg, this course will still teach you a lot — but the calculations and some breed-specific recommendations will need adjustment. Above 30 kg you really want to be looking at large-breed nutrition specifically.

Seven ways small and mid-sized dogs differ

1. Higher metabolic rate per kilogram. A 5 kg dog burns roughly twice as many calories per kilogram of bodyweight as a 50 kg dog. Smaller animals lose heat faster. This means small dogs need energy-dense food and tolerate missed meals poorly.
2. Smaller stomach, faster transit. A toy breed’s stomach holds maybe 30–50 ml relaxed; a Labrador’s holds 1.5 litres. Small dogs can’t eat a day’s food in one sitting — meals must be energy-dense and ideally split.
3. Dental crowding. Small dogs were bred down from larger ancestors but their teeth weren’t scaled down proportionally — crowded, overlapping teeth that trap plaque. Over 80% of dogs over age 3 show periodontal disease, small breeds worst.
4. Hypoglycaemia risk in young toy dogs. Toy puppies under 1.5 kg have so little glycogen reserve that missing a single meal can drop blood sugar dangerously.
5. Lower obesity threshold. Half a kilo of extra fat on a 5 kg dog is equivalent to 8 kg on a 70 kg human. Small dogs become obese on quantities that barely register on a Labrador.
6. Longer lifespan. A toy poodle living to 16 has eaten nearly 12,000 adult meals. Small errors compound over more years.
7. Faster maturation. Small dogs reach adult size at 9–12 months; large dogs take 18–24. The puppy-food phase is much shorter.

Breed-specific dietary flags

• Dalmatians and some Bulldogs: inherited purine metabolism issue — low-purine diets often recommended.
• Cavalier King Charles Spaniels: very high incidence of mitral valve disease — sodium control matters in middle age.
• West Highland White Terriers, Bichon Frise, Cocker Spaniels: higher rates of food sensitivity and atopic dermatitis.
• Miniature Schnauzers: prone to hyperlipidaemia and pancreatitis — dietary fat matters enormously.
• Bulldogs, French Bulldogs, Pugs: brachycephalic — benefit from kibble shapes for short jaws and slow-feeders.
• Dachshunds: obesity dramatically raises intervertebral disc disease risk — weight control is non-negotiable.
• Yorkshire Terriers: prone to liver shunts and pancreatitis; sensitive to high-fat diets.
• Jack Russells and high-drive working breeds: often underweight; need calorie-dense food in working seasons.

Key takeaways

• Small and mid-sized dogs aren’t scaled-down large dogs — their physiology demands a different feeding approach.
• The seven core differences all have practical feeding implications.
• Specific breeds carry specific dietary risks worth knowing.

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Practical task: Choose a real or hypothetical small or mid-sized dog. Record its breed, age, current bodyweight, body condition score (1–9), and any known health conditions. You’ll refer back to this dog in every later lesson.