Home SALUTE E BENESSERE - Health and Wellness Monitoraggio ovulazione e assistenza accoppiamento

Ovulation monitoring and breeding management

by Dr. Giovanni Majolino
Med. Vet.
Specialist in Small Animal Diseases
PAST-President of SIRVAC ( Veterinary Italian Society for  Companion Animals  Reproduction)
Labrador breeder, kennel name “della Lontra“


Due to several breeders’ number increasing need to optimise breeding programmes and the will to use studs who cannot be present during matings, veterinarians’ assistance at breeding is becoming more and more important.

The dog female represents one of a restricted numbers among the different animal species in which an ovulation of still immature and not directly fecundable cells occurs, in fact, it is necessary to wait 48 hours after ovulation since oocytes mature making fecundation possible by sperm cells.

“Puberty” in dogs starts around 9 month old as average, as to females and a little bit earlier as to males. A lack of puberty within 24 months of age is to be considered as pathologic (primary anaestrus) except for  a few breeds as Greyhound or other breeds of the same group .

Intervals among cycles usually last around six months but a shorter time can be also considered as physiologic or a single cycle per year, as well.

The heat starts when the bitch begins to show vaginal bleeding and oedematous external genitals and the consequent attraction from males that will last up to end of the season: such a stage, defined as proestrus, will last nearly 5/8 days. True oestrus last nearly 6/8 days, it is shown by swelling of the vagina area and noticeably less blood in the discharge together with the female featuring her holding her tail to the side and lifting the perineus when meeting a male.

Vaginal smears made during this stage are featured by superficial cells with irregular hedges and polyedrical shapes, during true oestrus, these cells become predominant  until they reach 100% of present cells when close to ovulation (see picture)

Making vaginal smears
Oestrus cytologic pattern showing sperm cells (after natural mating)

During the metestrus stage the bitch will quit flagging and will not be ready to breed anymore, showing a noticeably lack of interest in being friendly to males. At this stage cell-predominance in the vaginal smear will be of basal and para-basal cells, that is round regular shaped with a clearly seen centred nucleus. The stage of bleeding decreases and it lasts nearly 7 days.

Anaestrus follows the season until the next season starts and it is considered as a sexual rest period.

When mating sub-fertile females on when the breeder is oriented, for any reason, to artificial insemination (A.I.) with fresh, chilled or frozen semen, ovulation monitoring is a must.

Fresh semen is meant to be sperm collected from the stud and immediately used through A.I. of the present female. Chilled semen is set through a dilutor preserving it for some days. Diluted semen will be properly stored refrigerated at +5°C and shipped at the female’s kennel where she will be later inseminated. Semen fecundant ability is kept from 4/5 days, but better results are obtained within the first 48 hours. Frozen semen is meant to be concentrated sperm suitably diluted and frozen in liquid nitrogen stored sunk into liquid nitrogen TANK at – 196°C. Frozen semen is meant to be used only through A.I. into the uterus.

Detection of fertility highest peak  starts with making vaginal smears that start from the 4/5 day from the very beginning of the heat and then every other day until the typical cytological pattern of oestrus is to be read.

Now the veterinarian can start dosing progesterone on alternate days until the first increase to 2 ng/ml is detected; 48 hours later  the typical concentration of ovulation, that ranges between 5-8 ng/ml is reached, the moment of maximum fertility is considered 48 hours later with respect to ovulation DAY to let sperm cells reach mature and fecundable oocytes.

When mating in these days, nearly 95% of ovules can develop  as pups!( See picture showing fecundation).

Ovulation monitoring will become indispensable when choosing A.I.
Conception rate through A.I. with fresh semen and chilled semen, once ovulation is perfectly monitored, can be compared to that with natural mating, showing more or less the same number of puppies at birth.
As to my personal experience, over 150 females that have been monitored  and artificially inseminated with fresh and chilled semen, 84,8%  became pregnant.

But very different situation is when frozen semen is chosen (to be still approved by the Italian kennel Club , ENCI). Spermatozoa survival rate post-freezing range within 24 hours while fresh semen can be vital even after 6/7 days and  if suitably diluted and refrigerated will keep its vitality for 5 days garanting better results if used after 48 hours after collection.
Pregnancies rate from frozen semen is much lower than that with fresh or chilled semen and it can vary from 65-70% according to the insemination technique that must be into the uterus and not through vaginal deposition as it occurs with or chilled semen.

Catheters being used for vaginal A.I. are of 7-8 mm-gauge semi-rigid type,  with a total length that lets the catheter enter the vagina the more cranially possible keeping in mind that for example the Irish Wolfahound vaginal tract is approximatly 30-32 cm, the Greyhound is nearly 28-30 cm long, the Wippet is nearly 10-18 cm (see picture).

A.I. with frozen semen has to be made in uterus, are possible two techniques, a surgical one by depositing semen directly into the uterus mainly with the trans-cervical technique, after exteriorising the uterus body, through a surgical cut. Cervical catheterisation by endoscope is also used ( a non-invasive method that does not require any sedation) or by the so-called Norwegian catheter but blindly operating.

As to my personal experience, the technique I do prefer is the endoscopic - one  that can be performed using a suitable and sophisticated appliance (see picture) letting the veterinarian, through the vaginal canal, visualize the cervical ostium (passage from the vagina and the uterus body).
In this way it will be possible to insert through a service canal of the endoscope a 2/3 mm gauge catheter trying to go through the hardly accessible cervical canal, then de-freeze semen and implant it directly into the uterus.

Endoscopic image of the cervical ostium and relevant catheterisation

Breeding standpoints in our dogs’ life represent one of the different phases that we, as breeders, live with true and deep anxiety, hope and trepidation: the veterinarians’ professionality in assisting mating will be that of making richer as to good results dogs’ “breeding”.

 

Ambulatorio Veterinario
Dr. R. Ranieri Dr. G. Majolino
Vicolo Del Del Forno, 5
43044 - Collecchio (PR)

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Tel. +39 0521 800108
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