Thursday, September 30, 2010

Ovariectomy and ovariohysterectomy in dogs and cats

Sep 30, 2010 Perth Murdoch Vet Library
A cloudy day

A one-week break for Murdoch Univ students ending in Oct 3, 2010. I was surprised to see around 5-10 students at the Murdoch Vet Library for some time from 8.30 am to 6.30 pm to read their latest vet journals. Singapore has no vet library at all and so it is a great joy to read the various publications including old issues in this Vet library.

One article of great interest to small animal vets and new vets is in "In Practice" Jul/Aug 2010 Vol 32, No. 7 and also Sep/Oct 2010 No.8 as the two articles describe medical and surgical conditions of the reproductive system in the dog and cat in detail.

Before I get distracted and do other things, I will share my experiences of the past 30 years in small animal practice and also comment on the "surgical complications of spay" from Jul/Aug issue on "Surgical diseases of the female genital tract. Part 1. Ovaries and Uterus"

The authors mention that haemorrhage during spay is usually from the ovarian vessels and propose a solution - find the bleeding pedicle using "duodenal or colic manoeuvres." I have not heard of these manoeuvres. Always new things to discover. My solution is just to track the bleeding pedicle to the kidney area by parting the omentum and looking for the bleeding pedicle. An explanation or reference should be given by the authors.

Bleeding after spay can also be from:
1. Uterine blood vessels. The authors say that blood appears at the vulva.
2. Omental fat and the broad ligament blood vessels esp. when the dog is on heat.

If there is significant blood loss, repeat the surgery. The authors said to check the demeanour of the dog post op and check pulse rate and quality, PCV/total solids.


OVARIECTOMY is mentioned as an alternative to OVARIOHYSTERECTOMY in normal spays where there is no pyometra or neoplasia.


STUMP PYOMETRA AND REMNANT OF OVARIAN TISSUE
The authors say that if there are no remnants of ovarian tissue or use of exogenous progesterone (e.g. Ovarid being given to the dog), Ovariectomy will not lead to stump pyometra. Uterine neoplasia is very rare in the female dog and so Ovariectomy is OK. But most UK vets still do Ovariectomy.

In my 30 years in practice, I only encountered one case of stump pyometra in a dog spayed elsewhere. I excised the stump but did not do extensive laparatomy to look for the remnant ovarian tissues as the dog was old. The owner complained about vaginal discharge and pus happening even though the female dog was spayed.

BREAKING THE SUSPENSORY OVARIAN LIGAMENT attached to the kidney. In the early years, surgical books used to advise breaking the ovarian ligament using finger pressure.
I used this advice but it is not practical as sometimes the ovarian blood vessels get broken too. This leads to haemorrhage of the ovarian pedicle as mentioned by the authors and it is worrying.

Some 15 years ago, I use the scalpel blade just to cut off the ligament and then proceed to ligate the ovarian vessels. The ligament is quite taut and a scapel cut is so easy. I seldom have bleeding after spay unless the omental blood vessels of a dog in heat were bleeding. Very rarely do I have bleeding in the past 15 years.

DOUBLE LIGATURE OF THE UTERINE BODY.
I find this sufficient and have no post-op bleeding complaints or death. Transfixing ligature is an alternative in pregnant dogs. In pyometra, I invert the uterine body stump to prevent leakage of pus into the abdomen. Normally post-op antibiotics for 2 weeks prevent infection.

HOW LONG SHOULD THE UTERINE HORN BE LIGATED AND CUT OFF?
The authors said there is no worry about the ureters being ligated together with a longer uterine body. Ureters enter the bladder directly. In any case, if the ovarian tissues are completely removed, there will be no remnant ovarian tissues to cause vaginal discharge again. Ovaries are the only source of progesterone and if no exogeneous progesterone is given (e.g. Ovarid), the spayed dog will have no vaginal discharge regularly. Therefore, a shorter uterine body can be ligated without problem. Also uterine neoplasia is very rare in the dog. So, no problem here with a longer uterine stump left behind.

I don't excise too long a uterine stump in dogs, cats or rabbits. Just in case, the ureters are caught accidentally inside the ligatures. This may happen rarely but has not happened to me. Vet anatomy is full of surprises and one must be verfy careful not to be caught in cases of abnormal more cranial positioning of the ureters in the female dog.


SPAYING A PREGNANT DOG WITH PUPS
No problem with milk production as the dam will still produce milk even after spay during a caesarean section. Different hormonal pathways involved in milk production. This is where vet studies of endocrinology (4th year vet students to note) can be very useful in providing the answers as to whether milk production will cease once a dam is spayed during Caesarean section of dystocia and depriving the pups of the dam's milk.

BLOOD SEEN IN THE UTERUS AFTER SPAYING
The authors mention that blood seen after spaying could be due to haemorrhage of slipped ligature of the uterine body.

In the past 30 years, I had one complaint of the Lhasa Apso spayed by me. The owner complained of some blood seen. It could be due to incipient estrus. I noted a cystic lump in the uterus (starting of pyometra) and had taken photos. Blood stopped flowing after 2 or 3 days. The Lhasa Apso is very much alive and loved (if you see her blog or facebook) today.


LAPAROSCOPIC OVARIECTOMY OR OVARIOHYSTERECTOMY. The authors say specialised training is needed. I doubt there is a demand for such services as they will be very costly.

TIPS FOR INEXPERIENCED VETS
1. Spay is a major surgery.
2. Make a large incision from umbilicus to half way between umbilicus and pelvic inlet.
3. Get vet nurse to assist. (Use of abdominal retractors? I don't think the authors mention this).
4. Find the bleeding pedicle using "duodenal or colic manoeuvres." This was stated twice in the article but no further reference.

MY COMMENTS
Spay is easy if the incision is larger than 5 cm and be nearer to the umbilicus and the dog is not fat. I use a 2.5 cm incision but inexperienced vets should not cut so short as it takes time to learn how to hook out the ovaries. I have written several articles on my spay surgical approach in www.toapayohvets.com

FAT FEMALE DOG SPAY
I still remember a new Murdoch Univ vet graduate who worked for me some 20 years ago. He was unfortunate to get a big fat cross-bred of 20 kg. His brows were sweating as he could not locate the uterus despite a large incision. It took a bit longer to hook out the uterus in fat dogs. I still dread spaying fat dogs even though I have so many years of experience.

SPAY 3 MONTHS AFTER THE END OF HEAT
The authors did not include this advice but it is sound advice. Very little bleeding from the omental and broad ligament blood vessels. Even the ovarian and uterine blood vessels have shrunk in size.

LIGATING THE UTERINE BLOOD VESSELS AND TRANSFIXATION OF THE UTERUS
The authors advise this to be done. For me, I normally clamp the uterine body twice and ligate the whole body twice. In pregnant dog spay, I have to be careful and may ligate the uterine blood vessels separately via incision through the side of the uterine body and ligate before finally ligating the whole uterine body twice. This is overkill. Or I place a transfixing ligature.

DO NOT USE CATGUT
The authors say that catgut is not suitable. Something about capillary action (I need to check on this), fast dissolving and difficulty in knotting. I have not used catgut for the past 20 years. Like the authors, I use syntetic absorbable sutures. They definitely dissolve much slower.

Overall, the surgical articles in both issues are very useful to practising vets as part of their continuing education. Photographs are in colour and surgical approaches are shared. Episiotomy (extra-luminal tumour of the vagina) and episioplasty (excess skin folds around vulva causing dermatitis) surgical procedures are shown.


EPISIOTOMY FOR REMOVAL OF VAGINAL TUMOUR

The use of straight bowel clamps on either side of the vulva is a great idea as in horizontal ear canal resection. One arm of the clamp is placed inside the vestibule and one arm of the clamp on the perineum on the leftmost side of the tumour. Similarly for the other clamp to the rightmost side. The skin is cut in between. An assistant holds the clamp apart. The extralumninal vaginal tumour is seen cranial to the urethral orifice (catherised) and dissected. A beautiful photo shows the anatomy of the area with the urethral orifice seen clearly very well.

Closure in 3 layers - vaginal mucosa, muscle and then the skin.


EPIOSIOPLASTY
Stretch the loose skin upwards and sideways. Excise a crescent-shaped piece of skin above the dorsal aspect of the vulval lips. First incision around the 9 o'clock and 3 o'clock position. Then a parallel one dorsal. Stitch up after excision of the crescent piece of excess skin. Same surgical procedures as in entropion surgery.


INTERSEX
Excellent definitions of male pseudohermaphroditism (enlarged clitoris but testicles producing testosterone inside abdomen) and female pseudohermaphritism (small penis and ovaries inside scrrtoum), true hermaphroditism (have ovarian and testicular tissues)

For more details, it is best for vet undergraduates to rush to the Vet Library to download a copy. I am sure you will get HD (High Distinction is over 80%) in this fascinating animal sexuality topic in your stage of life.

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