Introduction

• Each individual animal has unique energy requirement.
• Energy is derived from dietary fat, carbohydrate and protein.
• Cause: (often) young animal fed homemade diet, poor quality, unbalanced diet.
• Signs: weight loss +/- failure to grow.
• Diagnosis: must rule out weight loss due to concurrent disease (because of legal welfare considerations).

Pathogenesis

Etiology

• Homemade diet: especially if based on vegetarian foods.
• Inappropriate commercial diet, eg adult food fed to puppy, adult food to bitch at peak lactation.
• Feeding too few calories for individual's requirements, eg high carbohydrate diet (fed to working dog), intentionally (by misguided owner) in large and giant breed puppies to decrease growth rate and hence decrease risk of developmental bone disease.
• Competitive feeding: dominant dog(s) fed simultaneously pushing out affected animal.

Specific

• Diet is bulk-limited: if its energy density is low → gastrointestinal capacity will limit intake before animal's energy needs are met.

Pathophysiology

• Correct amount of a balanced diet = animal's energy requirement + correct amounts of all other nutrients.

• Underfed animal→ uses liver glycogen stores → provides glucose essential for brain, blood, kidneys → if fasting for > 3 days → gluconeogenesis occurs using amino acids → mobilization of fat stores → supplies energy for other cells.
• Starved animal→ uses fat and protein as energy source (not carbohydrate) → decreasing fat stores noticeable over ribs/lumbar area → muscle atrophy over skull/lumbar region/limbs.

Timecourse

• Gradual: if uncomplicated starvation.
• Within days: if disease-induced, eg hypermetabolism and catabolism of amino acids providing energy and also maintaining antibody production, tissue repair, etc.

Diagnosis

Treatment

Prevention

Outcomes