Nutrition during the reproductive stages of dogs and cats is essential for optimising fertility, reducing obstetric complications, and ensuring appropriate growth of the litter. Management must consider the phases prior to mating, pregnancy, lactation and weaning, with defined objectives for each stage and based on complete and balanced diets that meet the metabolic demands of each physiological state.
Before mating
Females
Females should be in optimal body condition, equivalent to 5/9 on the nine‑point scale. Overweight animals show reduced ovulation rates, fertilisation failures, foetal dystocia, lower milk production and increased neonatal mortality. Underweight females also experience reduced fertility and compromised litter viability. A complete and balanced maintenance diet formulated according to AAFCO standards is recommended, with no need for supplementation. “Flushing” — increasing energy intake prior to oestrus — is unnecessary in female dogs and female cats with adequate body condition, unlike in some livestock species.
Males
Males do not have specific nutritional requirements, but adequate body and muscle condition is essential for optimal reproductive performance. In cases of intense service, weight loss can be corrected by increasing the energy density of the diet. Clinical assessment, together with evaluation of body and muscle condition, remains the key tool for monitoring nutritional status.
Pregnancy
Energy requirements
Energy needs differ between species:
- Female dog: progressive increase from week 5, with weekly rises of 10–15%, reaching 25–50% above maintenance at whelping.
- Female cat: linear increase from week 2, with expected weight gain of 40–50% by the end of pregnancy.
Adjustments must be individualised, avoiding both restriction and excess, as either can compromise foetal viability and maternal health.
Recommended diets
Diets should be highly digestible and energy‑dense:
- ≥4000 kcal/kg DM in female dogs
- ≥4500 kcal/kg DM in female cats
Protein must exceed maintenance levels:
- >29% DM in female dogs
- >32% DM in female cats
In female cats, taurine and arachidonic acid are essential to prevent foetal loss and ensure normal reproductive function. Protein quality, preferably of animal origin, is critical to avoid deficiencies in late pregnancy.
Minerals
Calcium supplementation is contraindicated, as it disrupts the Ca:P ratio (ideal 1:1 to 2:1) and predisposes to periparturient hypocalcaemia. In large‑breed dogs, strict control of calcium and phosphorus is essential to prevent osteochondrosis and skeletal development disorders. Mineral intake must come from balanced formulas, avoiding external supplements that disrupt homeostasis.
Lactation
Energy requirements
Lactation represents the period of highest metabolic demand.
- Female dog: 145 kcal/kg BW^0.75
- Female cat: 100 kcal/kg BW^0.67
A practical rule is to add 25% extra energy per puppy or kitten, up to a maximum of eight offspring. Beyond this, the mother may be unable to sustain adequate milk production.
Water
Milk production requires water intake numerically parallel to energy intake. A 30‑kg female dog with six puppies needs approximately 4500 kcal and 4500 mL of water per day. Constant access to fresh water is essential.
Production peaks
Peak milk production occurs in week 3 in female cats and week 4 in female dogs. Weaning should begin between weeks 2–4 in female cats and around week 4 in female dogs.
Nutritional management
Free access to energy‑dense diets and fresh water is essential. Gradual reduction of intake and transition back to maintenance diets around weeks 6–7 facilitates weaning and prevents metabolic complications. Monitoring body condition during lactation is critical to avoid excessive weight loss.
During pregnancy and lactation in large and giant‑breed female dogs, the main nutritional risks involve excessive calcium or an imbalanced Ca:P ratio.
Clinical intervention in large and giant breeds
- Do not supplement calcium during pregnancy if the diet is already complete and balanced.
- Recommend pregnancy/lactation diets formulated to meet energy needs and maintain Ca:P between 1:1 and 1.5:1.
- Monitor body condition closely.
- Educate owners: “more calcium” does not mean “more safety”.
- Prioritise high‑quality diets with strict control of energy and minerals.
Feeding litters when maternal milk is not available
Milk replacers
Commercial milk replacers are recommended, as they approximate the composition of canine and feline milk.
Not recommended
Milk from other species is unsuitable due to:
- lower caloric density,
- higher lactose → diarrhoea and malnutrition,
- risk of essential amino acid deficiencies (e.g., arginine).
Neonatal energy requirements
- Puppies: ~15–20 kcal/100 g BW/day
- Kittens: ~25 kcal/100 g BW/day
Neonates without maternal milk require species‑specific commercial replacers, never milk from other species.
Weaning
From week 4 onwards, maternal milk becomes insufficient. Offer gruel made from pregnancy/lactation or growth diets, moistened to ease intake
Conclusion
Nutrition during the reproductive stages of dogs and cats must be approached as a continuous process with defined objectives: optimising fertility, supporting pregnancy, ensuring adequate milk production, and enabling safe weaning.
Editorial note
Summary of the article Nutrition and Theriogenology, published in The Veterinary Clinics of North America: Small Animal Practice (vol. 53, 2023).
