Acute phase protein = Protein released during pregnancy which is the basis for commercial pregnancy testing kits. However, these proteins are also released in inflammatory conditions such as pyometra.

Acyclic = Occurring independently of a natural cycle of events. The menstrual cycle is an example.

Agenesis = Failure of a structure to develop properly. Examples are ovarian agenesis and uterine agenesis in the bitch.

Allantoamnion = The inner membrane formed when the membrane of the allantois fuses with the chorion during embryonic development.

Allantois = A membranous sac projecting from the ventral surface of the embryo which receives urine from the foetal kidneys. It eventually helps to form the placenta.

Amnion = The innermost membrane of the embryo which encloses the amniotic fluid.

Anorchia = Complete absence of testes.

Aplasia = Incomplete development of a tissue or organ or absence of growth.

Atresia = Absence of a natural opening. Examples are anal or vaginal atresia.

Breech = Foetus positioned in dorsal, posterior longitudinal presentation. The hind limbs are usually flexed and directed towards the dam's head. This may be a cause of foetal dystocia.

Bulbo-urethral glands = A pair of glands present only in the tom cat which produce a fluid that contributes to the semen.

Caesarean = Surgical operation involving an incision through the abdominal wall and uterus for delivery of the foetus/foetuses if a normal birth is not possible.

Chorio-allantois = The outer membrane formed when the allantois and chorion fuse during embryonic development.

Chorion = The outer layer of the developing embryo; the placenta.

Colostrum = A viscous, yellow fluid representing the accumulated secretions of the mammary glands over the final weeks of pregnancy. This contains immunoglobulins necessary for passive immunity of the foetus.

Congenital defect = A defect present at birth which is not necessarily inherited from ancestry.

Corona radiata = The outer protective layer of the ovum made of small follicular cells.

Corpus luteum = A solid structure developed from the follicle after ovulation which releases the hormones progesterone and relaxin.

Cryptorchidism = Testes retained within the abdomen; may be unilateral or bilateral.

Cystic endometrial hyperplasia = Small cystic lesions which develop in older females in response to progesterone during metoestrus. This may make the uterus more prone to infection and can lead to pyometra.

Dioestrus = Phase of the oestrus cycle following oestrus. In the queen this is represented by mature luteal phase, but in the bitch is often used synonymously with metoestrus (early luteal phase) to reflect the luteal phase of the cycle following standing oestrus.

Dystocia = Difficult birth. See key notes.

Encephalocoele = A congenital defect caused by a failure of the bones of the cranium to fuse. This results in a defect of the skull through which a portion of the brain bulges.

Endometrium = The mucous membrane lining the uterus.

Falciform ligament = The remains of the umbilical vein in an adult; a fat filled structure which runs from the umbilicus to the liver.

Fimbriae = The irregular processes found at the ovarian end of the oviduct.

First fraction = Clear fluid originating from the prostate ejaculated by the male prior to mounting. Its purpose is to flush urine and cellular debris from the urethra.

Follicle stimulating hormone = Hormone produced by the anterior pituitary which controls the maturation of the graafian follicles in the ovary.

Foramen ovale = A hole in the interatrial septum allowing mixing of blood from both sides of the heart. This closes shortly after birth.

Gravid = Pregnant.

Hereditary defect = A defect derived from ancestry. This may be congenital (present at birth) or develop later in life.

Hypocalcaemia = Low blood calcium levels. Also known as puerperal tetany or eclampsia. This is a serious condition that may affect the queen or bitch during pregnancy or lactation.

Hypogonadism = A rare condition resulting in poor development of gonadal tissue due to a primary abnormality in the secretion of pituitary hormones.

Interoestrus = Stage of non-receptivity in the oestrus cycle of the queen. This occurs in the absence of mating or if the mating does not result in ovulation.

Intromission = This follows ejaculation of the first fraction. The male sustains a full erection, mounts the female and his penis enters her vagina.

Lutenising hormone = Hormone produced by the anterior pituitary gland in late anoestrus which initiates the growth of follicles within the ovaries and subsequently causes them to release oestrogen.

Marginal haematoma = Vulval discharge post parturition which is green in the bitch and brown in the queen. It results from the degeneration of the maternal endothelium at the edges of the placenta.

Metoestrus = The early luteal phase of progesterone production.

Micropthalmos = A congenital abnormality in which the eyes are very small. It occurs most often in Pekinese. A hereditary type may occur in Great Danes and Collies.

Misalliance = Unwanted pregnancy.

Monoestrus = One oestrus period in each breeding season. The bitch is monoestrus.

Monorchidism = Describes an animal with a single testicle.

Multigravid = Pregnancy which is not the first.

Multiparous = Several young developing in one uterus.

Myometrium = The muscle tissue of the uterus.

Oestrogen = Hormone produced in the ovary which prepares the genital tract for coitus and reception of the fertilised eggs. (It is also produced in the testis).

Oestrus = Season; heat. Ovulation occurs during this phase of the reproductive cycle.

Orchitis = Inflammation of the testes as a result of trauma or bacterial infection.

Oxytocic = Drug which stimulates uterine contractions. Oxytocin may be given in cases of uterine inertia providing dystocia is not obstructive.

Paraphimosis = Failure to retract the penis into the prepuce.

Parturition = The act of giving birth.

Phimosis = Inability to extrude the penis.

Placenta = Vascular structure inside the gravid uterus which supplies the foetuses with nourishment via the umbilical cord. Post parturition, this is the afterbirth.

Poikilothermic = Body temperature which varies with that of the ambient temperature. Neonates are unable to regulate their own body temperature and are described as poikilothermic.

Polyoestrus = Multiple oestrus cycles within the breeding season. Queens are described as seasonally polyoestrus which means that they have oestrus cycles throughout their breeding season (February to September).

Polytocious = Numerous offspring produced in each litter.

Prepartum Hypothermia = Decline of about 2°C in the bitch's body temperature which precedes the onset of parturition by 24-36 hours. This occurs as a result of a sudden drop is plasma progesterone concentration.

Priapism = Persistent enlargement of the penis in the absence of sexual excitement.

Primigravid = First pregnancy.

Proestrus = The first stage of the reproductive cycle; plasma concentrations of oestrogen increase. The female is receptive to the male but will not allow mating.

Progesterone = Hormone produced by the corpus luteum of the ovary; essential for the maintenance of pregnancy.

Prolactin = Hormone produced by the anterior pituitary which stimulates milk production during late pregnancy and lactation.

Pseudocyesis = False pregnancy. In bitches non-fertile matings result in ovulation without conception during metoestrus.

Puerperium = The return of the reproductive organs to their normal state following pregnancy.

Pyometra = Infection of the uterus. This is a very serious condition. Open pyometra is characterised by a vulval discharge. Bitches must be speyed immediately.

Split oestrus = An endocrinological disease of the bitch; signs of proestrus which do not terminate in ovulation. A normal cycle follows 2-12 weeks later.

Standing oestrus = The bitch is receptive to the dog and stands to be mated.

Tie = The period following ejaculation when the dog and bitch remain in sexual contact. The dog dismounts from the female and turns through 180° with his penis still penetrating the bitch. The two remain back to back for at least 20 minutes and must not be separated. The purpose is to allow the third portion of ejaculate to flush sperm forwards through the cervix and into the uterus.

Uniparous = A single foetus developing in the uterus.

Vestibule = A space or cavity at the entrance to another structure. The vaginal vestibule is caudal to the vagina and continues into the vulva.

Zona pellucida = The glycoprotein inner membrane of the ovum.

Zonary placenta = The band around the middle of the extra-embryonic membranes of the placenta.