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Dog Breeding and increasing litter size

Updated on October 4, 2012

Canine Infertility and Obstetrics


Dog Breeding and increasing litter size

I'll take you through the many considerations in dog breeding

Canine Infertility and Obstetrics.

Points to remember

1. Be careful when asked, "Is it ok to mate my dog/bitch?

2. The infrequency of canine oestrus means that there are relatively few opportunities for a bitch to conceive in her lifetime.

3. The Kennel Club will not register litters born to bitches over 8 years of age and if she has had 6 or more litters.

4. The incidence of canine infertility is unknown.

5. If a bitch is not to be bred from she should be spayed at 6months of age to reduce the frequency of mammary tumours. Spay before 1st season incidence is 0.05% of expected rate, before 2nd season incidence is <10% of expected rate, after 2nd or more season’s incidence is 25% of expected rate and after 2-3 years the incidence is normal. There is no evidence to show that spaying at the time of mastectomy improves survival rates (cf. Breast carcinoma in women). Also, she won't be able to develop pyometra or pseudopregnancy.

6. A bitch should be spayed in anoestrus so that she won't develop a pseudopregnancy. We advise 3months after she has finished her season.

The oestrus cycle.

Puberty occurs as early as 6months and as late as 15months. Smaller dogs generally come into season earlier than giant breeds. Generally bitches are first mated on their third season. The bitch is seasonally monoestrus i.e. she has a single season usually at 6months intervals. However, some bitches have 4 or 12-month intervals. GSD’s and Rotties can come into season every 3 months and Basenji comes into season once per year. Whatever the time interval is it is usually retained throughout the bitches' life. An interesting fact is that bitches kept together often exhibit proestrus/oestrus around the same time. This is thought to be due to the release of pheromones from one pro-oestrus bitch stimulating the others.

Pro-oestrus is the beginning of a season and lasts on average for 9 days but is very variable. This stage is under the control of oestrogens. The changes in the wall of the vagina make the changes in vaginal cytology an indicator of the different stages of the oestrus cycle. The vulva swells, reddens and there is a serosanguineous discharge, the quantity of which varies greatly and is of no clinical significance. The blood comes from the uterus and so the cervix must be open. Indeed, some bitches remove most of it by licking- this is another reason why counting days is an unreliable indicator of ovulation. The bitch passes small frequent quantities of urine to disseminate pheromones. While she is attracted to male dogs she will usually not stand to be mated. Ovulation may occur towards the end of pro-oestrus.

Oestrus lastson average for 9 days but is very variable. It stars when the bitch will stand to be mated and ends when she refuses. The bloody discharge tends to become less copious and bloody but this is not a constant feature. Ovulation tends to occur towards the beginning of oestrus. Some ova are lost from ovaries of prepubertal pup- 700,00o eggs at birth, 250,000 by puberty, 33,000 by 5 years, and 500 by 10 years.

Some important facts are,

1. ovulation may occur as early as day 5

2. ovulation may occur as late as day 30

3. Ovulation may not occur on the same day in each season. It can vary by up to 12 days.

4. Ova are not ready for fertilisation when released. They have to undergo meiotic division, which takes up to 48 hours after ovulation and they are then fertile for 3days.

5. Sperm can survive in the bitches' genital tract for 7-10 days as they attach to the endometrium.

Because of these facts mating a bitch on days 11 and 13 may not lead to pregnancy. 80% will become pregnant.

Due to facts 4 and 5 bitches that are mated by more than one dog can have mixed litters.

Metoestrus starts when the bitch first refuses to stand to be mated and lasts about 60days. The vulva becomes less swollen and the bloody discharge gradually ceases. False pregnancies and pyometra occur during late dioestrus. Like in pregnancy there may be a mucoid discharge.

Anoetrus refers to the period between seasons when there is no ovarian activity. It can last from 1 month to 2 years but usually lasts 4 months.

Endocrinology.

1. Gonadotrophin-releasing hormone (GnRH) - released from hypothalamus in a pulsate manner and causes the anterior pituitary gland to release follicle stimulating hormone (FSH) and luteinizing hormone (LH). GnRH agonists initially cause stimulation but then inactivity of gonadotrophin producing cells because pulsate stimuli are prevented. This is known as down regulation and is used in medical 'neutering’ using Deslorelin.

2. FSH- stimulates growth of follicles in the ovaries. Factors, which stimulate its release, are not known. Binds to Sertoli cells and spermatogonia regulating spermatogenesis.

3. LH- stimulates the maturation, luteinization and ovulation of ovarian follicles. Ovulation occurs 30-48 hours after the LH peak. It is luteotrophic (maintains the function of corpora lutea). Binds to Leydig cells and regulates testosterone production.

4. Oestrogens- steroids produced by growing follicles. Cause the changes that occur in pro-oestrus. Raised levels in pro-oestrus decreasing in oestrus. Lead to a, vaginal discharge b, thickening of the vaginal mucosa c, change in cervical mucus consistency d,vulval swelling e, pheromone production f, behavioural changes

5. Progesterone- a steroid hormone produced by mature follicles and corpora lutea. Rises around time oestrogen peak. Stays high whether pregnancy occurs or not. Is high at time ovulation.

6. Prolactin- secreted by pituitary and is luteotrophic (maintains function of corpora lutea) ie tends to maintain an elevated progesterone concentration. Stimulates milk production. It causes signs of pseudopregnancy.

7. Relaxin –only known pregnancy specific hormone in the bitch. Produced by placenta. It causes the pelvic ligaments to relax during parturition. Is used to diagnose pregnancy in the bitch.

8. Prostaglandin's- don’t cause the lysis of the corpora lutea at the end of the non-pregnant luteal phase, as in other species. In the pregnant bitch prostaglandin causes the final lysis of the corpora lutea and the initiation of parturition. Canine CL is quite resistant to PG’s and need a number of injections to cause lysis of canine CL.

9. Oxytocin- produced in within supraoptic nucleus and transported axonally to storage sites in posterior pituitary. Causes milk let down and uterine contractions.

Monitoring the progress of the oestrus cycle.

1. Observation of bitch and her reaction if teased with male dog- very important

2. Vaginal cytology- using sterile bovine urinary catheter that has been cut into two and a 5ml syringe the contents of the cranial vagina are aspirated into the catheter. A drop of exudate is placed onto a microscopic slide and spread as a blood smear. During metoestrus and anoestrus a small amount of saline can be introduced into the vagina and reaspirated, to collect a suspension of cells. The slide is stained with Diff-Quik.

PRO-OESTRUS- parabasal, small intermediate and large intermediate epithelial cells. Small number WBCs. Large numbers RBCs and bacteria. Towards end pro-oestrus will see anuclear or cornified cells. They have a similar appearance to that of a 'cornflake'.

OESTRUS- early in oestrus maximal cornification (keratinisation) occurs, i.e. between 60-90% of cells are straight sided and have small (pyknotic) nuclei or no nucleus. There are usually no WBCs. There are variable amounts of RBCs. Bacteria are usually present but the slide may appear with a cleaner background than pro-oestrus.

METOESTRUS- returns back to parabasal and small intermediate cells. Massive influx of polymorphonuclear leucocytes. Usually no RBCs. No bacteria. This smear is similar to smears in pregnancy.

ANOESTRUS- parabasal and small intermediate cells. Low numbers WBCs. No RBCs or bacteria.

Determination of optimal mating time. Vaginal cytology indicates what stage of the oestrus cycle the bitch is in. It also indicates the fertile period but not the fertilization period. Vaginal cytology should start on day 5 of pro-oestrus. Mating should commence when more than 80% of cells are anuclear or there is an absence of WBCs. Blood progesterone levels can be measured once the bitch is in oestrus.

3. Monitor vaginal discharge and smell. Vulval softening happens at around the time of LH peak and is due to a fall in oestrogens and a rise in progesterone.

4. Vaginoscopy – PRO-OESTRUS- pink fluid and oedematous glossy folds. ONSET OESTRUS- pale colour and onset of wrinkling of mucosa. This stage generally occurs just before the LH peak. MID-OESTRUS pale creamy colour, marked wrinkling (shrinkage) and angular mucosal profiles. This corresponds to the middle of the fertile period. EARLY METOESTRUS- mucosal folds are rounded with pale patches, and irritable, sometimes closing to from a rosette pattern.

5. Hormone measurements. LH peak 48 hours before ovulation and 65 days before whelping. ELISA tests in USA. We measure the rising PROGESTERONE (P4) levels that occur before ovulation. IDDEX LAB is quantitative and so far better test than semi- quantitative (vet lab "ovulation test kit") or qualitative tests (premate).

BLOOD PROESTERONE LEVEL (ng/ml) STAGE OF CYCLE

A. undetectable late anoestrus

B. 1 late pro-oestrus

C. 2 LH peak. Ovulation 48hrs later.

D. 4-8 day of ovulation. Ova fertile 48hrs later.

E. >8 mate immediately.

Bitches will ovulate at different P4 levels but generally they ovulate when the value is between 4 and 8ng/ml. Daily ultrasound will tell us the definite day of ovulation but this is impractical in most situations. However, quantitative P4 levels work very well in clinical situations. P4 levels tell us

A, when to mate or AI the bitch

B, to confirm that ovulation has taken place. Don’t use LH to cause ovulation because may induce pyometra.

C, the expected whelping date and therefore, when a bitch has gone over

D, diagnosis of primary uterine inertia

E, misalliance, abortion or pyometra treatment has worked.

Measuring P4 also increases conception rates (CR) and litter sizes. Normal CR’s are 70-80% but these increase to >95%. For natural matings bitches should be mated when P4 levels has reached 4ng/ml and again 2 days later. When only 1 mating is possible or AI’s with fresh or chilled semen mate/AI the bitch once P4 has reached 7-8ng/ml. With frozen AI the bitch once P4 is 12ng/ml. We have had litters with frozen semen surgical AI’s when they where done at P4 levels 20-26ng/ml.

Mating the dog and bitch.

Have 3 people present. Allow dog and bitch to sniff each other, as this will tend to relax them. Sometimes bitches are sedated (ACP). When bitch is ready she will stand to allow the dog to mount her from behind, and she will raise her tail to one side and lift her vulva to facilitate intromission. The dog then mounts the bitch with his forelimbs gripping her tightly in front of her pelvis. After ejaculation the dog will want to dismount. With help from the handlers both front feet are placed to one side of the bitch, then the opposite back leg is lifted over the bitches back whilst turning round. Now the dog and bitch are bum to bum in the "tie" position, which lasts for about 15-45minutes. Don’t require a tie for conception to occur but since ejaculation of the sperm rich fraction of canine semen commences with the tie, the tie should be achieved wherever possible.

Gestation.

Lasts 58 to 71 days if calculated from day first mating to parturition because of the long behavioural oestrus period of the bitch i.e. bitch will stand to be mated even when she doesn’t have ripe ova. From day ovulation it is 63 days +/- 1 day. Litter size is smaller in young bitches, increasing up to 3-4 years age, and decreasing as bitch gets older.

Preparation of bitch and environment.

Move bitch to area of whelping weeks before parturition so she develops local immunity and is accustomed to her new surroundings. Whelping box should be easy to clean and have no draught. Temperature should be 30-33 degrees C for first 24 hours then decreased to 26-30 degrees C over the following 3-4 days. Newspaper is probably best bedding. Whelping box should be in separate room to the family or in a quiet corner. One side of the box should be small enough for the bitch to get away from the pups when she needs to.

Bitch should be vaccinated and wormed before mating. Panacur can be used in pregnant bitch from day 42 to whelping. Lopatol or Drontal Plus can be used before mating. Puppies are wormed at 2 and 5 weeks with Panacur liquid. It is rarely necessary to increase volume of food before day 40. I feed my pregnant and lactating bitches Hills Canine Growth, which is a complete balanced diet.

Pregnancy diagnosis.

1. Behavioural changes. There may be a brief period of reduced appetite 3-4 weeks after mating followed by an increase in food consumption by 50% after day 40.

2. Physical changes. Teats tend to become pink and erect with mammary gland enlargement from day 40. Colostrum can be expressed in last week pregnancy. Abdomen swells from day 40.

3. Abdominal palpation. Done at 4weeks. Some are better than others! Warn regarding resorption if bitch is pregnant. If can’t palpate "ping pong balls" then warn may still be pregnant.

4. I.D. fetal heart beats in late pregnancy. Heart rate twice that of the bitch.

5. Radiography. After 7weeks as fetal bones mineralized. Won't harm puppies.

6. Blood tests. Witness relaxin after day 24, if negative retest in 4 days time.

7. Ultrasound. Scan bitches from 28days. Can scan at 21 days post mating if P4 measured and therefore, now day of ovulation. If not best scan at 28 days post mating as won’t miss early pregnancies. Bitches can be scanned again at 7weeks in case she reabsorbs. Don’t count number pups just confirm whether bitch is pregnant or not.

Parturition.

Parturition means whelping. The breeder should start taking the bitch’s rectal temperature at least 3 times a day during the last week of gestation. A fall below 99 (37) indicates that parturition should start within 8-24 hours. The temperature is taken 3 times a day in case a low reading is false or transient. A fall between 5-8ng/ml of blood progesterone indicates that parturition will start within 14 hours. Several days before parturition, the bitch may become restless, seek seclusion or be excessively attentive, and may refuse all food. The bitch may show nesting behaviour 12-24 hours before parturition.

MAXIMUM OBSERVATION AND MINIMUM INTERFERENCE

Parturition is divided into 3 stages.

First stage.

The beginning of first stage is difficult to recognize. It normally lasts for 6-12 hours but can last for up to 36 hours in nervous maiden bitches. The vagina relaxes and the cervix dilates. Behaviuoral changes can include panting, tearing up and rearranging bedding, shivering, looking at her flanks and occasionally the bitch may vomit.

Second stage.

This is the stage when the pups are born. There are 3 signs, which indicate that the bitch has entered into second stage a) first water bag bursts (allantochorionic membrane) b) visible abdominal straining c) rectal temperature returns to normal.

This stage lasts for 3-12 hours. The first foetus is pushed into the birth canal. Covered by the amniotic membrane, the first foetus is usually delivered within 4 hours after the onset of second stage labour. Normally, the bitch will break the membrane, lick the pup intensively and sever the umbilical cord. Sometimes the bitch will need help breaking the membrane thus allowing the pup to breath. If needed, the umbilicus is clamped with sterile forceps and severed with blunt scissors. 1cm is left attached to the pup.

You should examine the bitch if;

1. THERE HAS BEEN STRONG, FREQUENT STRAINING WITHOUT PRODUCING A PUP FOR 50MINUTES. Ask breeder to check if there is a pup in vagina.

2. There is a greenish/red-brownish discharge but no pup is born within 2-4hours.

3. Fetal fluid was passed more than 2-3 hours ago but nothing more has happened.

4. The bitch has had weak, irregular straining for more than 2 hours.

5. The bitch has been in second stage labour for more than 12hours.

Third stage.

This is the passage of the placenta or afterbirth. It usually follows within 15 minutes of the delivery of each pup. However, 2 or 3 pups may be born before the passage of their placentas. The placentas should be removed as they may cause vomiting or diarrhoea if the bitch eats them. Vomiting may lead to life threatening aspiration pneumonia. A greenish discharge is normal following whelping and is the expulsion of fetal fluids and placental remains. It can last for 3 weeks. A mild bloody discharge can last until the next season. If not heavy and the bitch is otherwise normal then no investigation is required.

You should examine the bitch if;

1. All placentas have not been passed within 4-6hours ( make sure bitch hasn’t eaten them)

2. Discharge is putrid and/or foul smelling

3. There is continual heavy vaginal bleeding

4. The bitch is pyrexic or dull

5. The puppies are dull or wont suckle

Intervals between births.

Expulsion of the first fetus usually takes the longest. In normal whelpings the interval the interval between births is from 5-120 minutes. In large litters a bitch may rest and stop straining for more than 2 hours before starting second stage again. Parturition is usually completed within 6-12 hours after the onset of second stage labour. Remember that the onset of first stage labour is very difficult to recognize.

Dystocia.

Dystocia is the inability to expel the fetus through the birth canal without assistance. The incidence in the bitch is 5% but in certain breeds it can be 90% i.e. Bulldogs. 75% of cases are of maternal origin and 25% are of fetal origin.

A).Maternal causes.

1. Uterine inertia. Accounts for 72% of all cases of dystocia. Primary and secondary. In primary inertia the uterus fails to contract when there are only one or two pups because there is insufficient stimulation to initiate labour or because of overstretching of the myometrium by large litters. Measuring P4 levels at breeding or at whelping will diagnose primary uterine inertia. A CS should be performed when P4 levels is <2ng/ml. Secondary inertia is when parturition has started but stops due to exhaustion of the myometrium caused by obstruction of the birth canal.

Treatment regime;

A, running with the bitch, and feathering of dorsal vaginal wall (Ferguson reflex)

B, 10% calcium gluconate, 0.5-1.5 ml/kg (2-20mls) slow i/v monitoring heart rate. Wait 10minutes then give oxytocin 0.5 IU/kg i/m.

C, wait 30minutes then repeat above if necessary.

D, if after another 30minutes nothing has happened then perform a Caesarean section.

2. Maternal causes of obstruction of the birth canal include uterine torsion, uterine rupture, congenital malformations of the uterus, neoplasm’s, vaginal septa or fibrosis and those bitch’s with a narrow pelvic canal. These are all very rare accounting for 3% of all causes of dystocia.

B). Fetal causes.

Malpresentations account for 15%, malformations 1.6%, fetal oversize 6.6% and fetal death 1.1% of all cases of dystocia. I personally, don’t use obstetrical forceps for fear of damaging the pup or the bitch. I use lots of Lubrel jelly and my fingers. First, asses the position of the pup and correct any malpresentation. 40% of presentations are posterior. In these cases the pup is grasped in front of the hip joint. In anterior presentations the pup grasped between 2 fingers around the head. In both presentations caudo-ventral traction coinciding with the bitch’s contractions is applied.

65% of cases end up requiring a Caesarean. Fetal death increases from 6% in bitch’s brought in within 1-4.5hours after the beginning of second stage labour to 14% in the period between 5 and 24 hours.

Caesarean section.

Indications.

1. primary uterine inertia (P4 <2ng/ml)

2. secondary uterine inertia

3. unrelieved obstructive dystocia

4. fetal death with putrification

5. toxaemia of pregnancy and illness of the dam

6. prophylaxis (bulldogs, ethical?)

7. prolonged gestation >70days

Premedication.

Not normally required as bitch weak. Also, ACP causes maternal hypotension. We don’t use a premed.

General anaesthesia.

Induce with propofol (4-6mg/kg) and maintain with isoflurane. Can also induce with isoflurane when the bitch is weak. Propofol has a short duration of action. Isoflurane is mostly eliminated through breathing and less than 1% is metabolized in the body.

Analgesics are given pre- op. The best one is carprofen. A long acting antibiotic injection is given post-op. Oxytocin is given (5-20IU im) to hasten uterine involution and evacuation of fluids. Lactated Ringers solution i.v infusion at 10-20ml/kg/hr.

Surgical procedure.

A midline approach is preferred because it provides better access to the uterus, the bitch can lie comfortably on both sides and the pups don’t interfere with the wound if the skin is closed with subcuticular sutures. The bitch is placed in dorsal recumbency. Speed is essential to prevent fetal asphyxia and depression. Be careful when incising linea alba as gravid uterus in underneath it. The length of the incision depends on the expected size of the uterus and number of fetuses. The uterus is exteriorized with wet swabs (count them!) protecting abdominal contamination with uterine fluids. In large litters make an incision in middle of each uterine horn, for small litters make one incision in the uterine body. Incise between placentas. Remove pups in uterine body first.

Gently ‘milk’ pups to incision. Then grasp the fetus and gently rupture the amniotic sac to allow removal of the fetus. Clamp umbilical cord 1-2cm from fetal abdominal wall being careful not to cause an umbilical hernia. After each pup gently remove the placenta however, firmly attached placentas can be left in situ. Hand the pup to an assistant. MAKE SURE ALL FETUSES ARE REMOVED. Spaying increases anaesthetic time.

Uterus is closed using a continuous inverting suture pattern such as a Cushing or Lembert to invert the myometrium and appose the serosa. Vicryl on a round body needle is used for this suture. If there has been abdominal contamination it should be lavaged with warm sterile saline solution. Omentum may be placed over the uterine incision to minimize adhesion formation. Wipe the uterus clean. Close the abdominal wall conventionally. Make sure use subcuticular sutures.

The survival rates of pups delivered by caesarean section were 92% at birth, 87% after 2hours and 80& after 1 week. Only 9 out of 808 bitches died. The comparable figures for pups born naturally were 86, 83 and 75%. The breeds most commonly affected were bulldogs (17.2%), labrador retrievers (7%) and golden retrievers (4.5%). 34% cases used isoflurane both for induction and maintenance while 30% used propofol for induction with isoflurane for maintenance.

Diseases of pregnancy

Conception or implantation failure

Mating at the incorrect time is the most common cause of conception failure in the bitch. Behavioural signs of oestrus do not always correlate with changes in peripheral plasma hormones. Bitches can refuse to be mated during the fertilisation period and some bitches will stand to be mated outside of this period. Bitches can ovulate up to 12 days either side of their last oestrus ovulation.

Abortion/resorption

Incidence unknown but one or all pups can be reabsorbed. Classic ultrasound ‘snowstorm’. Causes include foetal defects, abnormal maternal environment, infectious agents and trauma. Brucella canis can cause early embryonic death or abortion late in pregnancy followed by a vaginal discharge. Not in this country. Other causes include CDV, CHV and Toxoplasma gondii. If there is an abortion the bitch will be ill with a vaginal discharge. Diagnosed by ultrasound and serological examination of the dam and bacterial isolation from the foetal membranes and stomach. Give the dam oxytocin, fluid therapy and antibiotics. Progesterone administration during pregnancy to maintain pregnancy should only be given after there has been a fall in P4 levels as it can cause pyometra, birth of masculinised female and cryptorchid males pups, and possible impair or delay parturition resulting in foetal death.

Canine Herpes Virus (CHV) can cause resorption, abortion, stillbirth and fading puppy syndrome depending upon when the virus replicates in the bitch. 80% of dogs in England have been exposed to CHV at some in their lives. CHV can also be a cause of kennel cough. Diagnosis is by PM or PCR. Merial have produced a vaccine (Eurican Herpes 205) against CHV.

Pregnancy hypoglycaemia

Rare condition that can lead to ketosis. Bitches weak and may become comatose. Measure blood glucose and treat with glucose i/v.

Post-parturient conditions.

Uterine disorders.

a. Haemorrhage. Scant haemorrhage, even, until the next season is normal. If the haematocrit falls below 30% uterine or vaginal tearing, vessel rupture or an underlying coagulation defect should be investigated. Inspect the vulva and vagina, give oxytocin and an exploratory laparotomy may be required.

b. Retained placentas/fetuses. Uncommon. Pyrexia, depression and a thick dark vaginal discharge. Diagnosis is via abdominal palpation, ultrasound or radiography. Treatment involves antibiotics, oxytocin 1-5 IU (bitch) or 0.5IU (queen) 2-4 times daily for up to 3 days. Exploratory laparotomy may be necessary.

c. Acute metritis. Usually gram –ve bacteria ascending through an open cervix following whelping manipulation, abortion or parturition in an unsanitory environment. Pyrexia, dehydration, depression, anorexia, poor lactation and mothering, and a purulent or sanguino-purulent vaginal discharge. I.V. fluids, antibiotics and oxytocin or prostaglandin F2alpha to evacuate uterine contents. Ovariohysterectomy may be required.

d. Subinvolution of placental sites. Suspected when serosangineous vaginal discharge persists longer than 6weeks. Usually <one year old. Cause unknown and bitch systemically O.K. Watch for secondary bacterial infections and anaemia.

e. Uterine rupture. Cause following prostaglandin or oxytocin administration, dystocia or normal parturition. Abdominal pain and distension and rapid deterioration of the condition of the dam. Diagnosis by exploratory laparotomy with ovariohysterectomy combined with fluids and antibiotics.

f. Uterine prolapse. Uncommon but usually within few hours after delivery of last neonate. Manual reposition via laparotomy may work but ovariohysterectomy usually required.

g. Toxic milk syndrome. Poorly understood condition where toxins are excreted into milk causing pups to become ill. Requires hand rearing.

h. Hypocalcaemia (eclampsia)

Fall in extracellular calcium concentration usually in small breeds within 21 days of parturition. Cause is probably calcium loss in the milk combined with poor dietary availability. Restlessness, panting, pacing, tremors, and stiffness progressing to muscle spasms. Fever, miosis, seizures and death. Slow I/V. infusion 10% calcium borogluconate solution 2 to 20mls in dog and 2-5mls for queen. Watch for bradycardia. Give 10% dextrose as hypoglycaemia may follow. Remove pups from dam for 24hours. Oral calcium during lactation 100mg/kg per day divided with meals with meals. Excessive oral calcium administration reduces intestinal absorption of calcium and inhibits the secretion of parathyroid hormone; although this is clinically significant in several species this does not appear to be the case in the bitch.

Mammary gland disorders.

a. Agalactia. Failure milk let-down or milk production. Nervous bitches may be given low doses ACP, pups allowed to suckle and oxytocin for failure milk let-down. Failure of milk production is uncommon but may follow premature parturition's or caesarean sections.

b. Galactostasis. Milk stasis usually affecting last 2 caudal glands (these are the most productive) causing enlarged firm warm glands that are sore to touch. Cause unknown. Gently massage and apply warm-water compresses to the glands. Reduce food intake and give frusemide.

c. Acute mastitis. Haematogenous and ascending bacterial infections into mammary glands. Hot, painful and enlarged glands. The milk shows increased viscosity and changes from yellow to brown colour. May be purulent. Pyrexia, anorexia and depression of the dam with pups restless and crying. Staphylococci, streptococci and E. coli are bacteria that are frequently isolated. Treatment includes broad-spectrum antibiotics, application warm-water compresses and massaging of the glands to remove the infected milk. Surgical debridement and drainage required if gland forms abscess or gangrenous.

d. Mammary tumours. These account for the largest proportion of neoplasms affecting the bitch. Two thirds of the tumours occur in glands 4 and 5, and in many bitches several other glands are also involved. The incidence of neoplasia is significantly reduced following ovariohysterectomy before puberty. Metastatic spread to the lungs is common. Radical surgical removal is the treatment of choice. Both oestrogen and progesterone receptors have been identified in malignant and benign tumours, for this reason both androgens and progestogens have been advocated to reduce tumour size prior to surgery. The anti-oestrogen tamoxifen has been used for the control of mammary neoplasia in the bitch, however the incidence of side effects which include vulval swelling and the presence of a vulval discharge, attractiveness to male dogs and nesting behaviour may preclude the widespread use of this agent. Can try Galastop before surgery to reduce size of mammay tumours.

Reproductive disorders in the bitch.

Pseudopregnancy

This is a normal physiological event in the bitch. Clinical signs may include anorexia, nest making, nursing of inanimate objects, lactation that may lead to mastitis and aggression. Conservative therapy may be sufficient in many cases although this may be supplemented by the adminidtration of diuretic and sedative agents. The treatment of choice is Cabergoline ‘Galastop’ at a dose of 5 mcg/kg/day. First make sure the bitch is not pregnant or has a pyometra. Cabergoline is a Prolactin antagonist. A permanent pseudopregnancy can be initiated by spaying a bitch during the luteal phase after day 30. It can treated with Cabergoline sid and then eod. Therefore, bitches should be spayed before day 30 of the oestrus cycle or at least 3 months after the end of oestrus. Clinical signs tend to recur after subsequent seasons. Spaying with prevent this.

Acromegaly

This is a rare condition caused by the chronic over secretion of growth hormone. Endogenous or exogenous progesterone may induce this condition. Clinical signs include pu/pd, abdominal distension, excessive skin folding in the facial area, overgrowth of connective tissue in the oral, pharyngeal and laryngeal regions, producing inspiratory stride and widened interdental spaces. The polydipsia is associated with a secondary diabetes mellitus. Progesterone induced acromegaly is not uncommon in the bitch during the luteal phase, and signs regress as progesterone concentrations decline. Treatment of these cases is by ovariohysterectomy although this may induce pseudopregnancy.

Pyometra

If a bitch lived long enough she would eventually develop a pyometra because this is end stage endometrial disease in the bitch. Progesterone induced endometrial hyperplasia leads to cystic endometrial hyperplasia that in turn leads to a pyometra. In cases of pyometra there is a secondary bacterial infection. 80% are E.Coli. The resulting endotoxaemia may lead to pu/pd, lethargic, anorexia, vomiting, dehydration and eventually collapse and death if the disease is not treated. If the cervix is open there will be a serosanguinous purulent discharge. Diagnosis is made by history, clinical signs, blood results, radiography, ultrasound and exploratory laparotomy. The treatment of choice is surgery. The disease can be treated medically but may recur. In conjunction with fluid therapy and antibiotics Cabergoline 5mcg/kg/day is used. After the cervix opens the prostaglandin Cloprostenol ‘Estrumate’ 5mcg/kg/eod is added to induce uterine emptying (the result of its spasmogenic activity) and to remove the stimulatory effects of progesterone (the result of its luteolytic action). Maybe better to use natural PG Dinoprost ‘Lutalyse’ 3-5 injections per day starting at 5 mcg/kg increasing to 40-50 mcg/kg. Can also use Alizin at 2 injections 7 days apart. Ultrasound and fall in P4 will confirm that treatment has worked. Continue antibiotics for 4 weeks after treatment has worked.

Misalliance

‘Mesalin’ contains a low dose of oestradiol benzoate. Giving oestrogen’s in the presence of progesterone increases the risk of pyometra so do not use. Also only 95% effective. We can measure blood progesterone, perform vaginal cytology, vaginoscopy and look for sperm from the vagina to asses the risk of the bitch getting pregnant. The bitch can be left and scanned in 28 days. If she is pregnant then one can use the prostaglandin Cloprostenol ‘Estrumate’ 5mcg/kg/eod for 10days and Cabergoline ‘Galastop’ 5mcg/kg/day for 10days. Start at day 28 and the pups will be reabsorbed with no vaginal discharge. The bitch should have no side effects and the results have been 100%. She can be spayed before day 30 without the risk of developing a permanent pseudopregnancy. When used in late pregnancy these drugs will induce abortion. The progesterone antagonist Aglepristone ‘Alizin’ is now licensed in the UK for misalliance treatment. 2 injections 24 hours apart from day 0-45 at 10mg/kg subcutaneously. Success rate is 100% for bitches treated between day 0-22 and 95% for bitches treated between days 23-45. Can induce pyometra if used later in pregnancy. 50% of bitches that are presented for misalliance do not get pregnant, so is it ethical to treat them all before pregnancy has been diagnosed?

Ovarian remnant in the bitch

Inject hCG (25 IU/kg). Measure oestradiol before and 8 hours later. A rise indicates ovarian remnant.

Induction of oestrus

A fertile oestrus can be induced in the bitch with Cabergoline (5mcg/kg/day). She will come into season more quickly when the drug is used in late anoestrus. When used in the luteal phase the treatment period will be longer and therefore more expensive. In anoestrus the treatment period is around 30 days compared to 70 days to 4months in the luteal phase. The mechanism of action is uncertain but it may be the result of inhibition of remnant progesterone production by the corpora lutea. The resulting pregnancy rate is 75-80% compared to only 50% when GnRH is used.

Juvenile vaginitis

This is a fairly common problem encountered in bitches from eight weeks of age onwards that usually regresses after the first season. There is a mucoid vaginal discharge, which may become purulent. Signs may also include frequent vaginal licking and attractiveness to male dogs. Severe cases may be controlled with low dose oestrogen’s daily for 5 days. Oestrogen’s are not licensed for this purpose and should not be given to bitches required for breeding. An alternative therapy is the topical application of oestrogen containing creams (Vagifem. NovoNordisk Pharmaceuticals Ltd).

Vaginal hyperplasia

Oestrogen causes vaginal hyperplasia in pro-oestrus. In some bitches this is exaggerated and there is a thickening and an increased vascularity to the vaginal and vestibular tissue. The ventral vaginal cranial to the urethral tubercle so oedematous that it protrudes through the vulvar labia. This occurs in late pro-oestrus and early oestrus and tends to recur in successive seasons. It may be inherited as it is seen most commonly in brachycephalic breeds such as Bulldogs and Boxers. The condition tends to resolve completely at the end of oestrus, so some cases can be treated conservatively. This involves keeping the prolapsed tissue clean and non-traumatized.

Ovariohysterectomy will prevent the condition recurring. Surgery is carried out during oestrus when the full extent of the protrusion can be seen. After performing an episiotomy the urethra is catheterized and the tissue is resected at its base on the vaginal floor cranial to the urethral tubercle. Diathermy is used to resect the tissue. The vaginal mucosal defect is closed with absorbable sutures. The bitch can be mated at the oestrus following surgery. Recurrence is uncommon following surgery.

Delayed puberty

Wait until the bitch is 24 months before making this diagnosis and make sure that the bitch has been carefully observed for signs of oestrus and if possible has been housed with another bitch in oestrus. Chronic disease and poor nutritional and environmental conditions may be associated with failure to cycle. Measure plasma progesterone to see if she has recently ovulated at an unobserved oestrus. Bitches cycle within 1 to 6months of attaining adult height and weight. Hypothyroidism has been associated with prolonged anoestrus and infertility. Cabergoline can be used to induce oestrus.

Prolonged anoestrus

The season may have been ‘missed’ by the breeder because the discharge was scant, the bitch quickly licked away any discharge or the season was unusually short. Plasma progesterone concentrations above 2ng/ml will indicate missed ovarian activity within the last two months. Thyroid function should be investigated. The diagnosis represents an interoestrus interval greater than anticipated for that particular bitch. Progesterone producing ovarian cysts may prolong anoestrus and causes CEH. These are diagnosed by ultrasound and serial measurement of plasma progesterone concentration. Gluccocorticoids, anabolic steroids, as well as androgens and progestogens can prolong anoestrus. Cabergoline can be used to induce oestrus.

Silent oestrus

This is where the bitch ovulates during a normal season but there are no external signs of proestrus or oestrus. This is seen in Greyhounds. Weekly vaginal cytology will show when the bitch is due and plasma progesterone will show when she has ovulated.

Split oestrus

Normally occurs at the first oestrus. Follicles grow; produce oestrogen so that proestrus occurs but then the follicles regress without ovulating. 2-12 weeks later she will have a normal season. It appears that the bitch has not ovulated or that fertilisation with subsequent foetal resorption/abortion has occurred.

Prolonged proestrus or oestrus

Majority of these cases are at the extremes of normality. Oestrus monitoring is all that is required. Oestrogen secreting follicular cysts may produce persistent oestrus in the bitch they are very rare. Treatment which involves ovariectomy should not be undertaken lightly since the bitch may have a normal but prolonged period of proestrus, or a persistent vaginitis (which causes local pheromone production causing males to be attracted). The persistent elevation of plasma oestrogen may lead to bone marrow suppression and thrombocytopaenia.

Ovulation failure

Diagnosed by serial plasma progesterone concentrations. Occurs in 1% of oestrus cycles. LH may induce pyometra.

Paul Boland BVSc, MRCVS




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      Johne215 3 years ago

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      Dr Mark 4 years ago from The Beach of Brazil

      Hi Paul well written article but I think you should look into the data being published about spaying a dog at her first heat; the incidence of mammary tumors do not justify all of the other medical problems that a dog goes through at that early date.