Breed guide
Cavalier King Charles Spaniel Breeding Guide: Litter Size, Whelping, Puppy Weights and Health Testing
Updated September 6, 2026 · 6 min read · By the BreedBloom team
Cavaliers are a beloved toy spaniel with two serious inherited problems, mitral valve disease and syringomyelia, that dominate responsible breeding decisions. The heart protocol in particular is well established, and buyers who have done their homework will ask about it.
Cavalier King Charles Spaniel at a glance
Typical litter size
3–6 puppies (average around 4–5)
Birth weight
6–9 oz (170–250 g)
Adult weight
13–18 lb (6–8 kg)
Gestation
About 63 days from ovulation (57–72 from breeding)
Whelping
Usually free-whelping, but small dams with singleton puppies can run into oversized-puppy problems; radiograph counts matter here.
Breeding and whelping notes
The MVD protocol: breed only dogs over 2.5 years with clear hearts whose parents were clear at 5. Auscultation by a cardiologist, not a general practitioner.
Syringomyelia MRI grading (A–D) is used to guide matings; the breed clubs publish the scheme.
Puppies are small; a 6 oz neonate has no reserve. Weigh twice daily and keep the box warm.
Cavaliers generally take to families easily and are placed young; do not send home before 8 weeks despite the pressure.
Health testing before breeding
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Heart: annual auscultation by a board-certified cardiologist for mitral valve disease (MVD); the MVD breeding protocol asks for parents over 2.5 years clear and grandparents clear at 5
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MRI screening for syringomyelia (SM/Chiari-like malformation) in many programs
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Eyes: annual CAER exam
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Hips: OFA
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Patellas: OFA
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DNA: episodic falling syndrome (EFS), curly coat/dry eye syndrome (CC/DE)
Keep the paperwork attached
Test results are only useful when they travel with the dog. Keep certificate numbers and dates on each dog's record and include copies in every go-home packet.
Tracking a Cavalier King Charles Spaniel litter
Enter the ovulation or tie date and BreedBloom builds the Cavalier King Charles Spaniel litter timeline: ultrasound window, X-ray count reminder, temperature checks, the day 3–16 ENS/ESI schedule, deworming and vaccination tasks, and per-puppy weight curves you can compare against the whole litter. Families follow along in the BloomPetz portal, and the go-home packet is assembled from the same records.
About these figures
Figures on this page are typical ranges drawn from breed club and veterinary references; individual lines vary. Confirm health-testing requirements with your breed's parent club, and whelping plans with your reproductive veterinarian.
Frequently asked questions
How many puppies do Cavaliers have?
Typically 3–6, average 4–5.
What is the Cavalier MVD breeding protocol?
Breed only dogs aged 2.5 years or more whose hearts are clear on cardiologist examination and whose parents were clear at 5 years. It is designed to push the onset of mitral valve disease later in the breed.
Do Cavalier breeders MRI their dogs?
Many do, to screen for syringomyelia and Chiari-like malformation. Results are graded and used in the breed club's breeding guidelines.
Run your program on BreedBloom
Dogs, litters, puppy weights, ENS/ESI tasks, waitlists, contracts and go-home packets in one connected record, with a family portal built in. Free for up to 3 dogs.
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