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      Date:   03 April, 2011  

Focus: Small animals - dogs, cats, hamsters, guinea pigs & rabbits

Toa Payoh Vets Clinical Research
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to a veterinary student studying in Australia
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Fools rush in where angels fear to tread - A massive neck tumour in a Syrian hamster
Dr Sing Kong Yuen, BVMS (Glasgow), MRCVS
03 April, 2011 
Be Kind To Pets
Veterinary Education
Project 2010-0129
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.

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?

"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.

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.

After being sedated with the correct, safe and effective amount of Zoletil 100, the 160-g hamster went down sideways as if she was going to sleep. There was a window of opportunity to operate as the analgesia of around 2 minutes permitted me to excise the lump and suture the skin wound without the hamster feeling the pain and struggling. Pain can kill the hamster on the spot.

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. "Pop out the lump!" my 2nd assistant said. I had 2 experienced assistants helping me and this is one factor of success in hamster surgeries. 

I could not pop the lump as it was not a discrete firm tumour as in many cases. I had to extend the skin incision by 4 mm as the globular tumour was just too big for a 1-cm incision done initially.

I saw a large vein from the lump (see illustration below). "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 vein?" I asked my assistant again. Once the jugular vein is accidentally cut, the hamster or person bleeds to death.

My assistant kept his mouth shut. It certainly was the biggest widest blue vein we had seen under the neck. About 3 mm wide and that is big when you consider that it is just a hamster, not a dog.

But it was connected to 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 (see illustration above). The tumour needs more nutrients and the blood vessels seem to enlarge to supply the ravenous growth.

I clamped the tumour and excised the lymphoid cum fatty tumour. Immediately,  blue black blood spilled out as if a dam had burst. The big vein was risky for me to ligate initially as it was very close to the pharynx. (Know your neck anatomy).

I dared not ligate by putting the needle under the vein as viewed from above. The needle might perforate the pharynx if I inserted it under the vein and then ligate the whole vein.

So I clamped and excised the big tumour first. A deluge of bluish-blood instantly filled the neck area and spilled onto the operating table. For a hamster, a loss of around 2 or 3 ml of blood is very serious as she is a very small creature, unlike a dog.

"Swabs, Give me one swabs" I said. Mr Saw was ready and provided the 3 swabs I needed to clear the bloodied area. I could see the bleeding area and ligated it. Then another big spurt appeared further near the neck. Was this the jugular vein? Was there any hope now. The blood was reddish, not bluish black. It was probably the artery injured during the first ligation. I inserted the needle under the area which is closer to the submandibular lymph node and ligated this second bleeder. No more bleeding now. You could imagine my relief. But the hamster looked dead. Circulatory shock and impending death appeared to cast black shadows on the life of this hamster now.

"Stretch the 2 cm skin wound by putting your thumb and index finger on either side so that the skin can be stitched properly," I said to my assistant. In this way, the skin wound is stretched out evenly 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 was of the essence. The hamster was just dead looking. The surgery must be short so that the hamster could be revived with subcutaneous dextrose saline injection and the body warmed by a hair dryer to prevent hypothermia.

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." He has had seen many hamster surgeries during his time with me.

"It is best to clean most blood before the hamster wakes up," I tried to swab off as much blood as possible as bacteria from the surrounding will infect the hamster via this outside blood. Blood encrusted on the neck area would attract bacteria and might even cause stress as the hamster wakes up.

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.

A massive tumour below the neck in a lethargic hamster is the type of high-risk anaesthetic situation I prefer not to operate. Generally the outcome is generally poor, meaning the hamster will die on the operating table. Such deaths are very emotional for both parties. Yet, surgery is the only option for the hamster to lead a normal life.  Pass the case to another vet?     

syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets older syrian hamster large cystic mixed tumour below neck risky anaesthesia and surgery toapayohvets syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets
I don't relish doing this highly risky surgery as this area is so small and has the jugular veins, the vagus nerves and many other blood vessels and nerves.
syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets
Surgical approach plan. Zoletil 100. No isoflurane gas used in this case. Note the large vein attached to the tumour. Tumour excised. Bloodied area cleaned. 5/0 absorbable stitches used. Barely alive. No signs of breathing. Hair dryer warms the body and SC dextrose saline injection 2.5 ml. 
syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets syrian hamster, female, 20months, soft nodular tumour below pharynx, surgical excision zoletil 100  toapayohvets
After an eternity, the hamster looked up. Then she started to hyper-ventilate for the next few minutes. It seemed like an eternity again. Would she live or die?
older syrian hamster large cystic mixed tumour below neck risky anaesthesia and surgery toapayohvets older syrian hamster large cystic mixed tumour below neck risky anaesthesia and surgery toapayohvets older syrian hamster large cystic mixed tumour below neck risky anaesthesia and surgery toapayohvets
24 hours after surgery, I was relieved to see that the hamster was active. Not eating due to the pain as I could see no faecal pellet produced. She was best nursed at home by the lady owner and in familiar surroundings. No complaint 3 days after surgery as I record this case 48 hours after surgery.   
  pug 7 months, injuries serious, deep central ulcerative keratitis, leakage aqueous toapayohvets singapore tpvets_logo.jpg (2726 bytes)


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