Pregnancy Diagnosis in Female Dogs – Clinical Methods

Dog Pregnancy Tests

On the next day, after breeding with a male. Fertilization of ova may take anywhere from 48 to 73 hours. For pregnancy diagnosis in dogs several methods are used. Some physical methods like evaluation of teats, weight gain, and abdominal enlargement are not reliable methods of pregnancy detection. More reliable methods include abdominal palpation (30 days gestation), measuring the level of relaxin hormone in the blood (26 days gestation), ultrasonographic examination of the abdomen (starting at 21 – 30 days gestation), and lastly radiographs of abdomen (mainly lateral view) (after 45 days gestation). Though these methods also vary in their ability to positively identify the number of foetuses and fetal viability.

Palpation:

Small ovoid swellings can be palpated manually along the uterine horns 21-30 days post breeding. These ovoid swellings increase and become double in the size every week until days 35 to 38; they then become confluent and difficult to differentiate. Abdominal palpation in pets is not as reliable as other methods for evaluating pregnancy in dogs. Neither fetal viability can be verified with palpation nor the exact number of foetuses can be determined without experience.

Relaxin Hormone:

Relaxin hormone is produced by the placenta and found in the bloodstream of the female dogs when the fertilized egg implants in the uterine wall, about 21 days (3-4 weeks) after mating. This hormone continues to circulate through the blood throughout the pregnancy, peaking around day 40 to 50. Witness Relaxin, Relaxin Pro, ReproCHEK etc are the current test kits in the market that measures relaxin in canine blood. This test can also be used continuously throughout the pregnancy to verify if total abortion has occurred. Pseudopregnant bitches do not test positive for election. This test cannot determine the number of foetuses present in the bitch. A false negative test is possible with lower relaxin levels when litter size is very small. It may be cost effective in comparison to ultrasound. And relaxin based diagnostic test kit results are fast, accurate and reliable and seldom gives a false reading.

Female dogs naturally produce higher levels of progesterone for two months after the stages of heat cycle. It is regardless of the breeding or mating. Therefore levels of progesterone in female dogs are not a reliable indicator of pregnancy.

Ultrasound:

Ultrasound is the best method used to visualise and evaluate the pups in the womb/uterus. Ultrasonography is the best tool for determining the pregnancy in dogs  21-30 days after breeding. Ultrasound done prior to 21 days can give false negative results. Ultrasound is a good method to differentiate between pregnancy and pyometra/ pseudopregnancy.

Fetal viability can be determined by ultrasound through visualisation of fetal heart. The number of foetuses can be estimated, though it can be less accurate in bitches carrying larger litters, or when done later in gestation. Cost of ultrasound is higher than relaxin based kits and radiography. Cost of ultrasound depends on the region and expertise of the veterinarian or technician performing it.

 

Radiographs:

At 28 days into pregnancy, the bones of the foetus begin to become calcified. At 42 -45 days of pregnancy, radiographs can be taken to visualise the pups in-utero. However, for best results, radiographs should be taken after more than 47 days of mating, when fetal skeletons are more readily visible. Radiographs can help in determine the number of foetuses, though it is less accurate in bitches carrying larger litters. Fetal viability cannot be determined by radiograph unless advanced lesions exist in the foetus, such as skeletal collapse or gas within the foetus or emphysematous foetus.

Pseudopregnancy / False Pregnancy / Canine Pseudocyesis:

This is also called phantom pregnancy, in this case a female dog exhibits same physiological symptoms of pregnancy like enlarged abdomen, weight gain, milk let down but foetus is not actually present. Best way is to rule out pyometra / mucometra / pseudopregnancy is ultrasound.

FAQs:

Que: how to terminate or abort a dog pregnancy at home?
Ans: Aborting a dog requires medication and should only be used under veterinarians’ prescription. Commonly used drugs for this purpose are cabergoline and bromocriptine.

Ques: how to prevent dog pregnancy after mating?
Ans: Preventing a dog pregnancy is different than aborting it. Most commonly used is hormone delvosterone and medicines like cabergoline and bromocriptine. But these must be used under supervision of a registered veterinary practitioner.

Que: Will a human pregnancy test kit work for dogs?
Ans: No. Pregnancy test kits designed for human are based on hCG (human chorionic gonadotropin) which is found only in women. Urine is used in such test kits while female dogs are tested for relaxin hormone which is found in blood.

Que: Are there over the counter tests / tests kits available for pregnancy diagnosis in dogs?
Ans: No, relaxin based test kits are available through registered vets or can be purchased online through websites / suppliers. But will need blood/serum to perform the test using a dog pregnancy kit.