Wednesday, June 9, 2010

96. Treatment of canine perianal (circum-anal) gland tumours

INTRODUCTION
Certain breeds (e.g. Siberian Husky), old dogs and intact (not neutered) males are more prone to perianal (circum-anal) gland tumours. The majority of tumours are benign and are called perianal (circum-anal) adenomas. The malignant ones are called adenocarcinomas. They can't be differentiated by visual inspection. A histopathology of the excised tumour is needed to check whether it is cancerous.



TREATMENT - 3 OPTIONS
1. Surgical excision. Most perianal gland tumours are benign but only histopathology can determine whether they are benign adenomas or malignant adenocarcinomas. Some vets don't perform this surgery as there may be worries of the wound not being able to heal and close. The client may get very angry as the dog will keep licking the open wound. Old dogs may die under general anaesthesia on the operating table leading to highly emotional scenes and potential litigation.

These are two main reasons why some vets don't want to operate. It may be kinder to pets for such vets to ask the owner to seek a vet who will operate as the dog licks the infected tumours to relieve its pain. Blood dripping from the backside can be quite inconvenient to the owner. Owners may need to be proactive in seeking early surgical removal.

2. Neutering. Perianal gland tumours are most common in male dogs that are not neutered. Seldom occur in female dogs. In this case, a female spayed Siberian Husky had one such tumour.

3. Hormone treatment.
Tardak is an anti-androgenic hormone. Injections may be effective but need to be given regularly when tumours occur.

Tardak is for use in male dogs and cats in the following indications:

3.1 The treatment of hypersexuality (humping, wanting to stray).

3.2 The relief of prostatic hypertrophy whether benign, carcinomatous or when due to chronic inflammatory processes. In inflammation, antibiotics and anti-inflammatory drugs are used too.

3.3 For the treatment of circum-anal (perianal) gland tumours.

3.4 For the treatment of certain forms of aggressiveness, nervousness, epileptiform seizures and corticoid-resistant pruritus (developing into dermatoses and accompanied by alopecia).

4. Chemotherapy and radiation for cancerous types. This is not normally available for Singapore dogs.
INTERESTING CASE STUDY
Female spayed Siberian Husky, 11 years old suffered from blood dripping from her perianal tumour for over 4 months. Tumour ulcerates and become infected. If you see the black spot below and to the right of the anus, there were early signs of perianal gland irritation, as the black spot is due to continual licking over several weeks.

CHALLENGES
1. High anaesthetic risk as in all old dogs. The owner did not wish to have a blood test. The vet must inform the owner of the need for such a test to screen the health of the dog before anaesthesia and surgery.

2. Large tumour over 3 cm x 3 cm very close to the anus. That meant a large wound after removal of the tumour and difficulty in achieving normal closure.

3. The dog passes soft stools during surgery, resulting in possible contamination during surgery and after.

4. If the dog rubs her backside on the floor after surgery, the stitches may break down. A large e-collar prevents licking of the wound.

PLAN AHEAD
I advised the owner to get her vet who did not want to operate, to do full grooming esp. of the tail area, ensure no maggot wounds and prescribe oral Baytril antibiotics for 6 days.

PRE-ANAESTHESIA
On the 6th day, the wound was not infected. The dog's rectal temperature could not be taken as the dog struggled and leaked out urine whenever her tail was to be held up for the insertion of the thermometer into the rectum. She was in great pain in the anal area and tried to bite to defend herself. More urine leaked out as she struggled. I got her muzzled for the IV drip and the injection via the IV catheter of Domitor 0.15 ml.

ANAESTHESIA
Dog got shaved. Isoflurane gas was given by mask. I intubated the dog and isoflurane at 1-2% ensured surgical anaesthesia. I got a towel to cover the metallic operating table to prevent electrical shock when I used electro-surgery to excise the perianal tumour. A swab with saline was placed on the indifferent plate and the dog's belly for the conduct of electricity during electro-incision and cautery.

ACTUAL SURGERY, JUNE 9, 2010 FROM 2.17 PM - 3.15PM
1. I used electro-incision to cut off the tumour. The dorsal part has a dark red mass of 0.5 cm x 0.5 cm. The main mass was hard, nodular and ulcerated. It was 2.5 cm x 2.5 cm. The shorter the surgery, the better the chances of survival.

2. A small artery at the ventro-lateral area nearer and below the anus spurted out red blood. I ligated 3 times. Coagulated the bleeding point. Finally, there was not much bleeding.

3. As the elliptical gap was large and under high tension, I had to reduce the tension in order to enable good wound healing. I extended the skin incision to the left at the dorsal and ventral edges above and below the anus respectively (see illustration). The wound was stitched with 3/0 sutures.

4. During closing, this dog kept passing out the loose stools despite her rectum being plugged by a 3-ml syringe. I replaced this syringe with a 5-ml syringe but the stools kept pouring out. This was be possibly due to the minimal isoflurane gas being used and therefore the dog's defaecation reflex was present. The dog's tongue was not a healthy pink and sometimes it turned cyanotic. Since the owner did not want a health screening blood test, it would be difficult to know if this dog had anaemia, hypercalcaemia, kidney or liver disorders.

POST SURGERY
The dog woke up within 10 minutes as if she had a good nap of over 30 minutes.
I gave 2.5 ml of anti-spasmogesic IV to prevent more loose stools coming out to contaminate the wound. She wore an e-collar. I phoned the owner to take the dog home. They came to visit her in the evening.

HISTOPATHOLOGY
The vet must inform the owner that there is histopathology to verify whether the tumour is cancerous or benign. In this case, the owner did not want it.

CONCLUSION
Neutering and surgical excision are recommended. Tumours are best removed when they are very small. I advise two anti-androgenic injections post surgery at 2-weekly intervals. Neutering your male dogs when they are young and/or weekly examination of the anal area will ensure that your dog live longer. This case has a happy ending. However, vets are not Gods and there will be deaths of old dogs on the operating table. It is best that the owner gets the tumours excised when they are very small in size.


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