Pregnancy and whelping in toy breeds demand more knowledge and more attention than in larger dogs. The margins are finer, the reserves smaller, the mistakes costlier. This piece is for those who want the detail: the timelines, the milestones, the risks and the moments when a vet must be called immediately.
Important note: this text is informative and professional in nature and does not replace veterinary care. Every pregnancy is individual. At the slightest doubt, always call your veterinarian.
Why the mating date is unreliable
This is the first thing every breeder must understand. Measured from mating, gestation varies between roughly 58 and 72 days. The reason lies not in the bitch but in biology: canine sperm survive in the female tract for up to seven days, and oestrous behaviour does not pinpoint ovulation.
Measured from a physiological marker, however, it becomes remarkably precise. From the luteinising hormone surge or ovulation, gestation lasts 64 to 66 days, averaging about 65 (Merck Veterinary Manual; Concannon et al.). From the onset of cytological dioestrus it is 56 to 58 days.
This is why determining ovulation through serial progesterone measurement is the foundation of serious breeding. It allows the due date to be predicted, preparation to be timely and, where needed, a safely planned caesarean.
A note on differing figures
Breeding circles often quote 63 days plus or minus two. That figure comes from older sources and from counting from mating. Modern reference sources measuring from ovulation or the LH surge give 64 to 66 days. The difference is not academic: a wrong starting point can mean recognising an overdue pregnancy too late.
The three stages of labour
Stage one usually lasts six to twelve hours, exceptionally up to twenty-four or even thirty-six. The cervix dilates; contractions are not yet visible externally. The bitch is restless, occupies the nest, pants, often refuses food and sometimes vomits.
Stage two is active straining and the delivery of puppies. About sixty per cent arrive head first and as many as forty per cent rear first; both are normal and no cause for panic.
Stage three is the expulsion of the placenta after each puppy. Stages two and three alternate until whelping ends.
Intervals between puppies are usually under thirty minutes but may range from fifteen minutes to several hours. A litter of six to eight can take four to eighteen hours in total.
The pre-whelping temperature drop
Roughly eight to twenty-four hours before whelping, body temperature falls to an average of 37.1 °C, with a range of 36.7 to 37.8 °C. In toy breeds it may fall further, to around 36.4 °C. The drop follows progesterone falling below 2 ng/ml.
What matters in practice: about eighty per cent of bitches show the drop, and a single reading has almost no predictive value. So in the last week we take the temperature two to four times daily and record it, to establish the bitch's own baseline.
When to call the vet immediately
This is the most important part of this text. The following criteria summarise veterinary guidance on dystocia (Merck Veterinary Manual):
Strong, persistent contractions for more than thirty minutes with no puppy delivered.
More than two hours between puppies when more clearly remain.
Active labour for more than four hours with no puppy.
Weak, intermittent labour for more than four hours without progress.
Total whelping lasting more than twenty-four hours.
Dark green or foul-smelling discharge before the first puppy. This indicates placental separation. Green discharge after the first puppy is normal.
Profuse fresh bleeding.
No whelping within twelve to thirty-six hours of progesterone falling below 2 ng/ml, or gestation exceeding about 66 days from ovulation.
Dystocia and caesarean section in toy breeds
Dystocia is strongly dependent on breed and litter size. In 2006, Bergström and colleagues showed a marked breed predilection in almost two hundred thousand insured Swedish bitches; O'Neill and colleagues confirmed this in UK data in 2017.
For toy breeds one finding is crucial and seems paradoxical: the highest caesarean risk comes not from large litters but from litters of one or two puppies. A single puppy grows larger while the uterus is insufficiently stretched to trigger strong contractions. The result is obstruction and inertia. In some datasets the caesarean rate in singleton litters exceeds eighty per cent.
Eclampsia: a toy-breed emergency
Eclampsia, or puerperal hypocalcaemia, must be known to every toy-breed owner. It occurs most often in small bitches nursing large litters, two to three weeks after whelping, when lactation peaks.
Signs progress from restlessness, panting and face rubbing, through tremor and stiffness, to incoordination, seizures and death. Total serum calcium below 7 mg/dl confirms the diagnosis. Treatment is urgent: slow intravenous calcium gluconate administered by a vet.
Why we do not supplement calcium during pregnancy
This is the most counter-intuitive point in the whole text, and one of the most important.
Supplementing calcium during pregnancy suppresses parathyroid hormone and with it the body's ability to release calcium from bone. When demand rises sharply with lactation, the bitch cannot mobilise calcium quickly enough. Supplementing calcium during pregnancy therefore increases the risk of eclampsia rather than reducing it. This is stated unambiguously by the Merck Veterinary Manual, VCA and Root Kustritz (2008).
The correct approach is a high-quality, balanced diet during pregnancy with no added calcium. Supplementation is appropriate only at peak lactation, and only in bitches with a previous history, on veterinary instruction.
Newborns of toy breeds
Toy-breed neonates have small hepatic glycogen stores, limited glucose production and a high metabolic rate. Reserves can be exhausted within twenty-four hours without suckling, and faster in weak puppies. Hypoglycaemia is therefore common and dangerous in them.
Birth weight strongly predicts survival. In 2020, Mugnier and colleagues measured mortality in 4,971 puppies across ten breeds: 4.2 per cent in normal-birth-weight puppies, 8.8 per cent in low and 55.3 per cent in very low birth weight. Thresholds are breed specific.
In practice: weigh puppies at birth and daily thereafter, expect five to ten per cent daily gain, keep them warm (a chilled puppy stops suckling and slides into hypoglycaemia), and at any suspicion apply glucose to the gums and call the vet at once.
A pregnant bitch's peace is not indulgence
Maternal stress hormones cross the placenta and affect puppy development. Tiira and Lohi, in over three thousand dogs, linked poorer maternal care with later anxiety; in 2016 Foyer and colleagues linked measured maternal care with offspring behaviour at eighteen months.
That is precisely why our pregnant bitches live in peace, without visitors, noise or change. This is not sentimentality but a breeding decision with measurable consequences.
Literature and sources
Merck/MSD Veterinary Manual: Dystocia in Small Animals; Eclampsia in Small Animals; Whelping in Bitches.
Concannon PW et al. (1989). Biology and endocrinology of ovulation, pregnancy and parturition in the dog. J Reprod Fertil Suppl 39:3–25.
Bergström A, Nødtvedt A, Lagerstedt A-S, Egenvall A (2006). Incidence and breed predilection for dystocia and risk factors for cesarean section. Veterinary Surgery 35(8):786–791.
O'Neill DG et al. (2017). Canine dystocia in 50 UK first-opinion emergency-care veterinary practices. Veterinary Record 181(4):88.
Drobatz KJ, Casey KK (2000). Eclampsia in dogs: 31 cases (1995–1998). JAVMA 217(2):216–219.
Root Kustritz MV (2008). Do not institute calcium supplementation during canine pregnancy. DVM360.
Mugnier A et al. (2020). Low and very low birth weight in puppies. BMC Veterinary Research 16:354.
Foyer P, Wilsson E, Jensen P (2016). Levels of maternal care in dogs affect adult offspring temperament. Scientific Reports 6:19253.
This text is based on current professional knowledge and on our kennel's experience. It does not replace consultation with a veterinarian or cynologist.
