VetRepro

Stories and thoughts about small animal reproduction and ultrasound


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Pregnancy diagnosis in the bitch and queen

Today I will try to summarize different methods that can be used for pregnancy diagnosis in the bitch and queen.

First of all, we have to remember that the embryo enters uterus on day 5-8. Attachment and maternal recognition occur on days 13-15 in the bitch and days 12-13 in the queen.

Clinical signs
The clinical signs of pregnancy are variable and unreliable. The primiparous bitch might show slight enlargement of teats on days 35 – 45.

Palpation
Abdominal palpation may give the veterinarian several diagnostic information. Segmental dilations can be palpated in the bitch from day 24 – 35 after ovulation and in the cat between day 16 – 26.
On the 3rd week the conceptuses are 15mm, round in shape, firm, well separated from each other. On week 4 they are 25mm, more oval, and on week 5:30-35mm, oval, soft, no separate structures anymore. After day 35 fetal vesicles enlarge and palpation is less accurate. Later on, fetal heads and bodies might be palpated. In large breeds and in bitches with tense abdomen or small litters palpation may be false negative.
Estimation of litter size is not possible. Finally, be careful: palpation needs to be as gentle as possible!

Ultrasound
Ultrasonography is the best method, safe and accurate. It allows the assessment of pregnancy status, and viability of the fetuses.
Gestational sacs are visible as early as day 18-20 after LH peak, but its recommend to examine not before day 21-25 because the small fluid-filled structures may be obscured by intestinal gas earlier.
Fetal heartbeat can be detected from days 16-25 in the queen and from days 23-28 in the bitch. Fetal heart rate should be more than 200 beats per minute as decreasing rate indicates fetal stress. Several ultrasound methods can be used to calculate it.

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Estimation of fetal heart rate with Pulsed Wave Doppler

After day 28 in the queen and days 34-36 in the bitch fetal movements are present.
Parturition time can be estimated with measurement of gestational sac diameter, crown-rump length and head diameter.
In contrary with what is believed, ultrasonography is NOT the method of choice for assessment of litter size. Counting number of fetuses is difficult, especially in large litters.

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Canine fetus, day 39

Radiography
Enlarged fluid filled uterine horns can be observed by day 21-42 but they cannot be distinguished from that seen with uterine disease, pyometra for example.
First skeletal mineralization occurs by day 42. The degree of fetal mineralization can be used to assess gestational age and predict whelping date.
Radiography is useful more in late pregnancy, when it can be used to identify litter size and fetal size in relation to birth canal.
During the first trimester of pregnancy (organogenesis) there is high risk of radiation damage, but later in gestation this risk is minimal and not greater for fetuses than for the bitch.
Signs of fetal death after 24 hours include presence of gas within or around the fetus and collapse of the axial skeleton.

Hormones
– Relaxin
Is produced by placenta. A serum test is available and can be used from day 24 after ovulation. Estimation of relaxin gives no information about number or viability of the fetuses. The test remains positive for an undetermined time after pregnancy loss occurs. In general, it is not commonly used.
– Progesterone
Progesterone is not indicative! It remains high in all normal dogs during diestrus regardless of breeding status or pregnancy as in the bitch is produced exclusively from corpus luteum. Some studies have documented slight difference in the pattern of progesterone of pregnant and not pregnant bitches but interpretation needs several measurements of serum concentration.
– Prolactin, FSH and estrogen
There are differences in concentrations but not practical to use.

Several other things about pregnancy diagnosis can be written and further analyzed, so if you want we can always come back later!

Thanks for reading! See you soon!

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The normal parturition of the dog

So at last, time has come! Your dog is ready to be a mother and you are ready to become grandmas and grandpas!

At the following lines we will try to explain you in a simplified way the physiology of canine parturition, and to present you some tips in order to be ready to welcome the new members of your family! Greek speaking people feel free to click the following link:

Ο φυσιολογικός τοκετός στη σκύλα

The first question that usually arises is “when”?

In general canine gestation (pregnancy) lasts 63 days, but can range from 59-68 days. Record the dates of all successful breedings on a calendar. For bitches bred over more than once, choose the middle date to count from. 56-57 days after breeding, start monitoring your bitch for other signs of labor. If your bitch has not whelped by 65 days, an X-ray or (better) ultrasound is recommended. Milk production begins 1-3 days prior to parturition, but this can range a lot (some bitches can produce milk 7 days before whelping while some others willnot have milk evident until after they are in labor). In primiparous lactation begins with parturition. In pluriparous lactation may begin days before parturition. The temperature of almost all bitches will drop approximately 24hours before parturition. Owners should start measure bitch’s temperature two to three times per day from day 57 of pregnancy. Most bitches will refuse to eat 4 to 24 hours before they go into labor. This is normal and expected. Do not try to force your dog to eat! If anorexia continues and does not correspond with other signs of impending parturition for more than 48, you’d better contact your vet.

Ok, now get ready for the big day! 

When delivery time is coming, you will have to prepare a few items, such as:

  • A whelping box
  • Bedding, newspapers
  • Plastic bags
  • Disinfectant and cleaning material
  • Suitable bags for disposal of placentas or stillborns (in cases that histological examination is needed)
  • Therometer
  • Pen and a table to write down the rectal temperature
  • Clock
  • Table to record timing of contractions, times of delivery
  • Gloves
  • Lubricant
  • Cotton
  • Dental floss to tie the umbilical cords
  • Scissors
  • Blankets
  • Cleaning towels
  • Marker pens to mark the puppies
  • Bottles for feeding or syringes
  • Commercially available colostrum
  • Water for the mother during labor

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And what happens during parturition?

The labor in dogs has three stages. The first stage (about 12h) is clinically unapparent. The bitch is restless, indifferent to food and shows nesting behavior. Uterine contractions increase and the cervix dilates. During the first uterine contractions bitches frequently change their position but stay recumbent during straining efforts. The uterine contractions are very weak and are therefore notvisible externally.

Duiring the second stage contractions will become more and more frequent. The cervix will be fully open and she will be ready for delivery. The dog needs to be calm and you need to provide a warm and quiet room for the delivery. The onset of the 2nd stage may be difficult to recognize due to the bitches movements when abdominal straining begins. The allantochorionic membrane of the first fetus appears and reaches the size of a golf ball. The bitch breaks it by licking. The delivery of the head needs the greatest effort, the rest usually follows without delay. The expulsion of the first puppy may last one hour. About 40% of puppies are expulsed in posterior presentation, which is absolutely normal. The puppies remain attached to the umbilical cord up to its rupture post partum. After expulsion of the first puppy the bitch rests for some time and licks the puppy until it shows signs of viability. She licks the vulvar discharge and eats the placenta which is expelled within 10-15 minutes (this is the third stage). Sometimes, more pups may be delivered before the membranes are expelled. A delay up to 24 hours may occur until the expulsion of all fetal membranes is finished. The bitch may try to eat the fetal membranes. Because this may lead to vomiting and/or diarrhoea, it is recommended that the membranes are removed. The second and third stages are then repeated. After 30-120 minutes delay,  straining recommences. The interval between two puppies is about 30-60 minutes. The second stage  lasts 3-12 hours in bitches.

Stay tuned and till then, congratulations on your new arrivals!!!


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Radioprotection in the veterinary practice

On Sunday January 31st, I was invited to give a short lecture about radioprotection in the veterinary practice.

Ionizing radiation is not a new or unknown field for me, as I was a member of Greek Airforce’s NBC (Nuclear, Biological, Chemical) Medical Response Team from 1998 to 2007. Apart from that, the effects of any type of radiation on the reproduction system and on the fetus are also of great importance for me because of my special interest in small animal’s reproduction. One of my latest research project has to do with the potential effects of specific types of electromagnetic radiation in pregnant rats.

So those of you that might find something interesting in my presentation, you can read the attached pdfs! One in Greek and one translated in English!

Have a nice week!

Radioprotection and the role of the vet-Greek

Radioprotection and the role of the vet-Engl

 


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Twitter and reproduction of rodents. Part 2.

Time has come for the 2nd part…

Chinchillas

https://upload.wikimedia.org/wikipedia/commons/5/5f/Standardchinchilla.jpg

Chinchillas become sexually mature at an average age of 8 months: females 8.5 months (2-14), and males at 8 (4-12) months.

They are polyestric animals.  Females cycle seasonally (November to May in northern hemisphere). They come in estrus every 28-35 days. They also present postpartum estrus: 12 hours after parturition! Estrus lasts 3-4 days, perineum becomes reddened, the normally tightly closed vagina opens and expels a wax-like plug. Vulval swelling is not present.

Mating occurs biannually. Chinchillas form monogamous pairs or can be kept in harems. Gestation lasts 111-128 days. Pregnancy can be detected by palpation at 90 days. Litters size is 2 (1-6). Parturition occurs early in the morning. Newborns are fully furred and have their eyes open. They weigh 30-50 gr. Weaning occurs at 6-8 weeks, but they are able to eat solid food quite early (from the 1st week) as they are born with teeth!

 

Rats

gray-rat

Female rats are polyestric animals and they come in estrus every 4-5 days.

Social groups of rats are often formed of multiple males and multiple females. One male is dominant and a linear male hierarchy may form. The species is polygynous, and the dominant male is the most successful breeder. Territories and mates are defended through aggressive behavior.

Rats are able to breed throughout the year if conditions allow. The peak breeding seasons are summer and autumn. Females can produce up to 5 litters in one year. The gestation period ranges between 21 and 29 days, and young rats are able to reproduce within 3 to 5 months of their birth. Babies are born with closed eyes and hairless. Weaning occurs at 3 to 4 weeks of age.

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Pregnancy diagnosis of the rat at the 8th day (Image by George Mantziaras)

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Heart rate estimation of a rat fetus at the 12th day of pregnancy (Image by George Mantziaras) 

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Ultrasound of a rat fetus on the 18th day of pregnancy (Image by George Mantziaras)

 

Mice

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Breeding onset is at about 50 days of age in both females and males. Mice are polyestrous and breed year round. They are spontaneous ovulators. The duration of the estrous cycle is 4–5 days and estrus lasts about 12 hours. Vaginal smears can be used to determine the stage of the estrous cycle. Mating is usually nocturnal and may be confirmed by the presence of a copulatory plug in the vagina up to 24 hours post-copulation. The presence of sperm on a vaginal smear is also a reliable indicator of mating.

Female mice housed together tend to go into anestrus and do not cycle. If exposed to a male mouse or the pheromones of a male mouse, most of the females will go into estrus in about 72 hours.

The average gestation period is 20 days. A fertile postpartum estrus occurs 14–24 hours following parturition, and simultaneous lactation and gestation prolongs gestation 3–10 days owing to delayed implantation. The average litter size is 10–12. Inbred mice tend to have longer gestation periods and smaller litters than outbred and hybrid mice. The young are called pups and weigh 0.5–1.5 g , are hairless, and have closed eyelids and ears.They are weaned at 3 weeks of age.

 

Gerbils

gerbils-species-photo

Gerbils reach sexual maturity at 10 to 16 weeks. They are polyestrous and they cycle every 4-7 days. They form monogamous pairs.

Gerbils will mate for several hours, in frequent short bursts followed by short chases, when the female allows the male to catch her. Once he catches her, the female will squeak and make flick motions to get the male off her. Males will not attack females except in rare circumstances, which may also include them having been separated from their original mates, or widowed. A female may attack a male, but usually he is more than a match for her. Copulatory plugs form in the reproductive tracts of females that hinder subsequent matings. The presence of these copulatory plugs suggests a polygynandrous mating syste

Gerbils may also experience postpartum estrus and delayed implantation, such that a new litter begins developing as soon as the first is weaned. Gestation periods, if females are not lactating, last 3 to 4 weeks, longer if lactating. Overall, litter sizes range from 1 to 13, although litters of 4 to 7 are much more common. Young gerbils are born completely naked and blind. Eyes open about two or three weeks after birth. The young can walk quickly and hop about on all fours at about three weeks. At around one month of age, the young are weaned and independent.

 

Hamsters

hamster-health.png

Hamsters reach puberty at the age of 6-8 weeks. They present estrus every 4 days.

Hamsters, as cricetines,  are promiscuous, with males and females both having multiple mates. During mating, a copulatory plug forms and seals the female’s reproductive tract, preventing subsequent males from successfully fertilizing the female’s eggs. A female hamster often drives a male out of her territory soon after mating.

Cricetines are seasonal breeders that mate and raise their litters from February to November. Females bear 2 – 4 litters per year. Gestation is short, lasting 15 to 22 days, and litter sizes average 5 to 7 (1-13). Young hamsters nurse for about three weeks, and are sexually mature at six to eight weeks.

 

That’s all for rodents’ repro for the moment. I’m not sure if there will be a 3rd part. Maybe yes, if you ask for that!

Thanks for reading,

Bye bye till the next time!

George