{
  "id": "dog-pregnancy",
  "version": "8207ec253220",
  "status": "published",
  "name": "Dog Pregnancy Calculator",
  "question": "When is my dog pregnancy due?",
  "summary": "Computes the whelping date window of a pregnant dog from the breeding, LH surge, ovulation or diestrus date, with how many days along she is and when ultrasound and X-ray checks work.",
  "category": "days",
  "subcategory": "dates",
  "url": "https://www.acalculator.org/days/dog-pregnancy-calculator",
  "markdown": "https://www.acalculator.org/days/dog-pregnancy-calculator.md",
  "kind": "function",
  "method": "Due date = event date + the middle of Merck’s gestation window: 65 days from the first breeding (58 to 72), 65 from the LH surge (64 to 66), 63 from ovulation (62 to 64), 57 from the first day of diestrus (56 to 58).",
  "assumptions": [
    "Gestation lengths are from the Merck Veterinary Manual; the estimate is the middle of each window.",
    "Days are counted from the event date as day 0; ultrasound from day 25 and X-ray from day 45 count from the same date.",
    "Breed, the number of litters and the litter size also change the length, so a vet check is the final word."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "from": {
        "title": "The date I know",
        "description": "Which event the date is: the first breeding, the LH surge or progesterone rise, ovulation, or the first day of diestrus.",
        "type": "string",
        "enum": [
          "breeding",
          "lh",
          "ovulation",
          "diestrus"
        ]
      },
      "d": {
        "title": "Date of that event",
        "description": "The day of the first breeding (mating), LH surge, ovulation, or first day of diestrus.",
        "type": "string",
        "format": "date"
      },
      "on": {
        "title": "Today’s date",
        "description": "The day to count from, to show how far along the pregnancy is.",
        "type": "string",
        "format": "date"
      }
    }
  },
  "outputs": {
    "due": {
      "label": "Estimated due date",
      "description": "The middle of the normal whelping window.",
      "format": "date"
    },
    "earliest": {
      "label": "Earliest normal due date",
      "description": "The event date plus the shortest normal gestation.",
      "format": "date"
    },
    "latest": {
      "label": "Latest normal due date",
      "description": "The event date plus the longest normal gestation.",
      "format": "date"
    },
    "days": {
      "label": "Days along",
      "description": "Whole days from the event date to today’s date.",
      "format": "integer"
    },
    "left": {
      "label": "Days to the estimated due date",
      "description": "Whole days from today’s date to the estimated due date; negative once it has passed.",
      "format": "integer"
    },
    "stage": {
      "label": "Where she is now",
      "description": "The stage on today’s date, in one line.",
      "format": "text"
    },
    "ultrasound": {
      "label": "Ultrasound check from",
      "description": "Day 25 after the event date, when Merck says ultrasound works best.",
      "format": "date"
    },
    "xray": {
      "label": "X-ray puppy count from",
      "description": "Day 45 after the event date, when the puppies’ skeletons show on X-ray.",
      "format": "date"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "from": "breeding",
      "d": "2026-09-02",
      "on": "2026-10-02"
    },
    "outputs": {
      "due": "2026-11-06",
      "earliest": "2026-10-30",
      "latest": "2026-11-13",
      "days": 30,
      "left": 35,
      "stage": "Day 30: an ultrasound can confirm the pregnancy.",
      "ultrasound": "2026-09-27",
      "xray": "2026-10-17"
    },
    "text": "Her puppies are due about November 6, 2026, between October 30, 2026 and November 13, 2026."
  },
  "examples": [
    {
      "given": {
        "from": "breeding",
        "d": "2026-03-01",
        "on": "2026-04-05"
      },
      "expect": {
        "due": "2026-05-05",
        "earliest": "2026-04-28",
        "latest": "2026-05-12",
        "days": 35,
        "left": 30,
        "ultrasound": "2026-03-26",
        "xray": "2026-04-15"
      },
      "source": "Merck Veterinary Manual, Whelping and Queening in Bitches and Queens (58–72 days from the first breeding), https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/whelping-and-queening-in-bitches-and-queens; hand calculation in content.mdx: 1 March + 58, 65 and 72 days"
    },
    {
      "given": {
        "from": "lh",
        "d": "2026-12-20",
        "on": "2027-02-21"
      },
      "expect": {
        "due": "2027-02-23",
        "earliest": "2027-02-22",
        "latest": "2027-02-24",
        "days": 63,
        "left": 2
      },
      "source": "Merck Veterinary Manual, Breeding Management of Bitches (parturition 64–66 days after the LH peak), https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/breeding-management-of-bitches; hand calculation in content.mdx"
    },
    {
      "given": {
        "from": "ovulation",
        "d": "2028-01-01",
        "on": "2028-03-10"
      },
      "expect": {
        "due": "2028-03-04",
        "earliest": "2028-03-03",
        "latest": "2028-03-05",
        "days": 69,
        "left": -6
      },
      "source": "Merck Veterinary Manual, Approximate Gestation Periods (dog 62–64 days from ovulation), https://www.merckvetmanual.com/multimedia/table/approximate-gestation-periods; hand calculation in content.mdx"
    },
    {
      "given": {
        "from": "diestrus",
        "d": "2026-06-10",
        "on": "2026-06-10"
      },
      "expect": {
        "due": "2026-08-06",
        "earliest": "2026-08-05",
        "latest": "2026-08-07",
        "days": 0,
        "left": 57
      },
      "source": "Merck Veterinary Manual, Whelping and Queening in Bitches and Queens (56–58 days from the first day of diestrus), https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/whelping-and-queening-in-bitches-and-queens; hand calculation in content.mdx"
    }
  ],
  "sources": [
    "Merck Veterinary Manual, Whelping and Queening in Bitches and Queens (Davidson, updated June 2025): normal gestation 56–58 days from the first day of diestrus, 64–66 days from the progesterone rise or LH surge, 58–72 days from the first breeding. https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/whelping-and-queening-in-bitches-and-queens (retrieved 2026-10-02)",
    "Merck Veterinary Manual, Breeding Management of Bitches (Davidson and Carnevale, updated July 2025): parturition 64–66 days after the LH peak; due dates 56–58 days after the first day of diestrus. https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/breeding-management-of-bitches (retrieved 2026-10-02)",
    "Merck Veterinary Manual, Approximate Gestation Periods (dog 62–64 days from ovulation). https://www.merckvetmanual.com/multimedia/table/approximate-gestation-periods (retrieved 2026-10-02)",
    "Merck Veterinary Manual, Pregnancy Determination in Bitches and Queens (updated January 2026): ultrasound best at 25–35 days; relaxin after 22–27 days; skeletons on X-ray from about day 42–45. https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/pregnancy-determination-in-bitches-and-queens (retrieved 2026-10-02)"
  ],
  "related": [
    "dog-age",
    "date",
    "days-since",
    "weeks"
  ],
  "changelog": []
}