ANS 200: Companion Animals

Dog Reproduction

II.     Dogs

        A.     General Terms

                1.     Male–Dog
                2.     Female–Bitch
                3.     Young–Pup or Welp
                4.     Group–Pack

        B.     Breeding age

                1.     Puberty

                        a.     Female--9-12 months
                        b.     Male--10-12 months
                        c.     Smaller breeds reach puberty earlier than larger breeds

                2.     Reproductive lifespan

                        a.     Female–6-10 years
                        b.     Male–6-14 years

        C.     Cyclicity

                1.     Type and Season of Cycle

                        a.     Biestrous
                                i.     Estrus at 4-8 month interval in Spring and Fall
                        b.     Monoestrous
                                i.     Seen in some breeds

                2.     Length of Sexual Cycle

                        a.     Proestrus
                                i.     9 days
                                ii.     Bloody discharge
                        b.     Estrus–7-9 days

                3.     Duration of Heat (Estrus)
                        a.     7-13 days

                4.     Time of Ovulation
                        a.     2nd or 3rd Day of Estrus

                5.     Viability of Ova
                        a.     A few day

        D.     Mating

                1.     Precopulatory Behavior

                        a.     Search

                                i.     Bitch–Roaming
                                ii.     Dog–Roaming around territory

                        b.     Courtship

                                i.     Bitch–Immobile Stance
                                ii.     Dog–Sniffing and licking of vulva

                        c.     Consummation

                                i.    Bitch
                                      A. Tail deflection to one side
                                      B. Urination in presence of male
                                      C. Affectionate head rubbing
                                ii.     Dog
                                        A. Erection
                                        B. Protrusion of Penis
                                        C. Mounting

                    2.        Copulatory Behavior

                                a.     First Stage Coitus

                                        i.     Mounting and intromission by a few thrusting movements

                                        ii.     1st and 2nd fractions of semen are ejaculated

                                                A.     1st Fraction–Pre-sperm 
                                                        1.     Seminal fluid from prostate
                                                        2.     0.5-5 ml
                                                B.     2nd Fraction–Sperm Rich
                                                        1.     300 million to 2 billion sperm
                                                        2.     1-4 ml

                                        iii.     1-2 minutes
    

                                b.     “The Turn”

                                        i.     Transition phase
                                        ii.     After ejaculation, dog lifts one leg and turns around while lifting one leg over the bitch
                                        iii.     Penis remains in bitch vagina
                                        iv.     Lasts 2-5 sec.

                                c.     Second Stage Coitus, “The Tie”

                                        i.     Animals stand with hind quarters in contact and their heads facing opposite directions
                                        ii.     3rd fraction of semen is ejaculated
                                                A.     Post-sperm fraction
                                                        1.     Seminal fluid from prostate
                                                        2.     1-80 ml
                                                        3.     Forced cranially to push sperm-rich fraction into the uterus.
                                        iii.     Encourages Uterine rather than Vaginal insemination
                                                A.     Penis stays engorged and acts as plug
                                        iv.     Lasts 5-45 minutes

        E.     Pregnancy

                1.     Gestation
                        a.     58-63 days

        F.     Parturition/Lactation

                1.     Parturition

                        a.     Welping
                        b.     Nesting behavior 24 hours before
                                i.     Welping will be inhibited if environmental conditions aren’t right
                        c.     Lasts 4-5 hours
                        d.     Pups delivered at 60-90 minute intervals
                        e.     Bitch is very protective of pups

                2.     Littersize 
                        a.     4-8 puppies
                3.     Mammary Glands
                        a.     10
                        b.     2 ventrolateral series
                4.     Weaning age
                        a.     6-8 weeks
                5.     First estrus after parturition
                        a.     Next heat period