Friday, April 1, 2011

Fools rush in where angels fear to tread - A hamster's large neck tumour

SURGICAL AREA
A big soft lump from below one ear to another and dangling under the neck in an old Syrian hamster (female, 20 months). This is the type of surgical condition I dread most. Performing this type of surgery is "fools rush in where angels fear to tread". The neck area has many important nerves, arteries and veins and it is not a very dangerous area to remove tumours especially in a hamster. That area below the throat is so small (less than 1 cm) compared to a dog or cat. A few thousand times smaller. There is no luxury of using an operating microscope and in any case, the surgery must be short as the hamster can't survive long anaesthesias of more than 1 minute, in my experience. You can't top up anaesthesia as in the dog and cat. Any more anaesthesia, the hamster just dies.

ANAESTHESIA
Very risky in a lethargic hamster. That means the hamster is not normal and healthy. The owner of this case waited till the neck tumour becomes very large. Is it inoperable? In any case, the chances of the old and lethargic hamster surviving are much lower. Less than 10%. So why take the case and risk damaging one's hard-built reputation as a "killer" of hamsters when this Syrian hamster dies on the operating table? Why not pass the buck to other vets?

DOSAGE OF INJECTABLE ANAESTHESIA IS HARD TO CALCULATE
"How much to give?" I asked my assistant Mr Saw (as part of my training of the past 3 years with me). He will be going to greener pastures in 2 weeks' time. "One drop of Zoletil will do," Mr Saw said. The owner had already said the hamster was lethargic for the past 2 weeks and the lump had exploded to big size during this time. Therefore, minimal dose as recommended by Mr Saw was the correct thing to do.

I gave one drop of Zoletil by injection IM into the left backside muscle. Waited for 5 minutes. The hamster looked at me and behaved normally, walking around inside the plastic container. She ought to be sleepy but she was much wide awake.

I waited another 5 minutes. She was active and had produced more faecal pellets. So, this dosage given was not effective. "In Syrian hamsters (160g), you need to give 4 times the dosage of a dwarf hamster (40 g)," I said to Mr Saw. But how do you calculate the dosage? It is easy in dogs and cats because they weight in kg when adult. But in this adult old hamster, she was 160 g.

"Give 2 drops," I asked Mr Saw to prepare the Zoletil. He filled up Zoletil 100 in one one-ml syringe and then push out one drop from its tips. Then I should use another one-ml syringe with a fine needle to aspirate the two drops.

"Hey, it is better you rest your elbows on top of the operating table," I said as it is hard to be precise in the present set up. "I also put my hands on top of the table." I then used the tip of my 25G needle attached to my one-ml syringe and aspirated two full drops from Mr Saw's one-ml syringe tip.

I injected into the right backside muscle. Within one minute, the hamster was lying down on his back.

So far, the Providence had been kind to me. The hamster was down but not out. Not dead I mean.

IV DRIPS
Impossible to do in a hamster. The veins are too small. SC injection of up to 3 ml dextrose saline is possible and was done in this case post-op.

SURGERY
After being sedated with the correct, safe and effective amount of Zoletil 100, the hamster went down sideways. There was a window of analgesia for around 1 minute to get the lump excised and the skin sutured.

I incised the skin 1 cm. A glistening membrane of the lump appeared under the skin. It seemed to be cyst but it was not 100% fluid filled lump. I saw a large vein from the lump (see illustration). "Is it the jugular vein?" I asked Mr Saw to make him think. He kept quiet. We had never seen jugular veins in hamsters in previous surgeries. Well, this location of the tumour was the second one I encountered during the past years of practice.

Know your anatomy well. It was not the jugular vein. I was just making my assistant think about hamster anatomy. He photocopied many veterinary notes and illustrations to prepare himself for the setting up of a private practice in Yangon later in the year. But nothing beats photocopies like seeing the real thing.

"Is it the jugular?" I asked my assistant again. He did not reply. It certainly was the biggest widest blue vein we had seen under the neck but it was connected to the tumour some below the tumour mass. It was unlikely to be a jugular but since the neck area is so small in size compared to that of a dog or cat, it would be hard to discount its presence. As a guideline, any large vein connected to a big tumour would be a feeder vein and the artery would be next to it. The tumour needed more nutrients and the blood vessels seem to enlarge to supply the ravenous growth.

I clamped the tumour and excised. Immediately blue blood spilled out. This vein was hard to ligate initially as it was very close to the pharynx. I dared not ligate as the needle might perforate the pharynx. So I excised the tumour first. Around 3 ml of blood splashed out. "Swabs," I said. Mr Saw provided the 3 swabs I needed to clear the bloodied area. I could see the bleeding vein. Ligated it. Then another big spurt appeared. It was probably the artery injured during the first ligation. I ligated this second bleeder. No more bleeding.

"Stretch the 2 cm skin wound by putting your thumb and index finger on either side," I said to my assistant. In this way, the skin wound is stretched out and I could appose the cut skin with 3 horizontal mattress sutures quickly. The hamster's neck was not straight in this type of surgery. No luxury of tying up 4 legs and positioning the head on a pillow as in the dog surgery. The hamster was just too small to do all these. Time is of the essence. Surgery must be short.

My assistant said as I cut out the bits and pieces of this mixed tumour and started wiping off the large amount of blood from below the eyes to shoulder: "Stop, I can clean the blood off later. The hamster is going into shock soon. Stop and wait. Do not stress the hamster."

I tried to clean up as much blood as possible as bacteria from the surrounding will infect the hamster via this outside blood.

The hamster started panting. Breathing at more than 100x/minute. Why? Stress had set in. Was she going to die?

My 2nd assistant took out a hair dryer, set to lowest warmth and warm up the hamster. "Give 3 ml of dextrose saline SC," I asked Mr Saw to stop as he started to get normal saline. It was not possible to give an IV catheter as in the dog because it is practically impossible to get a hamster's vein and I doubt if anybody can do it. The hamster is just so small and everything is miniaturised. So subcutaneous fluid was OK. But it must be dextrose saline in my opinion and this can be given by SC. Glucose itself cannot be given SC.

As everything was so tense, the vet must have a clear mind and ensure that proper drugs and saline are given by being observant.

After an eternity of more than 30 minutes of being kept in a warm room, the hamster breathed normally. I took a photo of her trying to stand up. It was a good sign. In 24 hours, I took her photograph and was glad that she was alive. Not all stories end happily all the time for all vets. It is best for owners to check their older hamster early for small tumours. These are easier to remove and take a much shorter time.


More pictures are at www.toapayohvets.com. Click HAMSTERS


For more pictures of the surgery: goto

http://www.sinpets.com/F6/20110323massive-neck-tumour-syrian-hamster-surgery-toapayohvets.htm

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