Thursday, May 20, 2010

75. An old cat's two puncture wounds would weep all day long

An old cat's two puncture wounds would weep all day long
Dr Sing Kong Yuen, BVMS (Glasgow), MRCVS
Date: 08 June, 2010
Be Kind To Pets
Veterinary Education
Project 2010-0129

Getting ideas from vet assistants is one way of improving oneself as they are in the front line of nursing and have many ideas to resolve veterinary challenges. I am constantly amazed that I have not encountered every situation even after 30 years of practice and therefore I do ask my assistants how they would handle certain cases. Vets cannot know everything because there are so many surprises in new situations in veterinary medicine and surgery, as you can see in this commonly encountered case of two puncture wounds in an old cat.

An 11-year-old female spayed cat came in with two puncture wounds on her left flank. The wounds would not heal because they erupted a light brownish red fluid every day. Just like an active volcano.

Yet this cat was not feverish. The two wounds in the skin were around 4 mm x 4 mm. But they just would not close.

"The bite wounds are not superficial on the skin only," I said to the father and two adult daughters. "I would need the cat to be put under anaesthetic and explore the inside of the skin for debris. Therefore the cat must be warded for treatment." I gave the old cat an antibiotic and the tolfedine painkiller injection and put her in the crate for one day of observation.

On the morning of Day 2, I noted that the wounds were still weepy. My assistant VA2 had sprinkled his favourite yellow antibiotic powder onto the two wounds after cleaning up yesterday. Yet on the next day, the wound wept and all his yellow powder would spill out and downwards onto the lower body of the cat. This cat's subcutaneous fat had been melted away by the bacteria introduced by the other cat's saliva and so there was loose skin. The muscle layers had torn out and the jagged edges were producing the brownish red fluid.

"Just flush the inside of the skin with a 20-ml syringe," Thomas replied when I asked him how this case ought to be handled.

"You know, the suction pump is perfect for this case," I said. Thomas had never seen a suction pump being used in his 20 years of assisting in veterinary surgery. It is rarely used but is useful in certain conditions like peritonitis after surgery and maybe in some Caesarean sections.

"No need to use this equipment. Just flush normal saline via a 20 ml syringe," Thomas replied. The suction pump seemed lie a piece of fancy equipment to Thomas. This would be the first time he would see how useful this machine could be.

All old cats are high anaesthetic risks. This cat was thin but she looked very young. She just did not have a large appetite normally and weighed 3.3 kg when a good weight for her size would be 5 kg. There would be 2 anaesthesias needed for two surgeries and the owner must be informed in advance as to the costs, to avoid misunderstanding.

The first one would be to debride and flush out the dead muscle and fat cells. Then, on the next day, the cat would be anaesthesized to stitch up the normal skin edges after snipping off the rotten edges of the puncture wounds. There was no other way and so the risks of the cat dying on the operating table would be doubled. Definitely, the owner should be asked to sign the surgery consent form and receive advices on the prognosis.

Zoletil 100 @ 0.2 ml IV femoral vein was given. Isoflurane gas via the mask was given to supplement as over 30 minutes were needed. I needed to cut away dead skin and muscle cells from damaged layers. Thomas said: "The muscle layers need to be stitched up, otherwise the cat would continue to have fluid production. When stitched, there would be no problem."

I said: "This is a very old cat. Healing of the wound will be slow. To stitch up the torn flank muscles, I would need to cut a bigger skin incision to reach deep into the muscles layer near the belly. If the big wound does not heal, the cat would be in trouble. If this is a young cat, it will be OK."

I observe that the cat could walk normally and so I would not advocate stitching of the irregular torn flank muscles. In old cats and dogs, it is best not to create big skin incisions. About 1000 ml of normal saline were squirted into the big space between the skin and the left flank muscles. A big suction tube pulled out yellowish fat and dead cells. I used scissors to snip off jagged muscle edges.

After the suction was completed, I checked the cat half an hour later. The cat was on an IV drip of normal saline. She was shivering. "Take the rectal temperature," I said to my intern Teresa. She put the thermometer in the rectum and showed me 33.5 deg C. This was low and worrying. Her normal temperature should be 38.5. This old cat had not taken anaesthesia and flushing well. Thomas blew hot air onto the cat using the hair dryer and rubbed her with a towel. "Give 20 ml of glucose," I said. This was given. The cat was wrapped with a towel. 2 hours later, her temperature was 36 deg. She growled as she did not like temperature taking. By the next morning, her temperature was normal. What was the cause of this hypothermia? "Irrigation of the flank with normal saline," Thomas said. This was plausible. I would think it was more the after effects of Zoletil as well.

24 hours after the flushing, there was no more weeping wound. The flesh looked pink. I masked the cat and gave isoflurane gas and she did not struggle. Stitching was done using horizontal mattress sutures, walk-in-sutures onto the muscle before stitching the skin and 2 appositional sutures using 3/0 absorbable. The cat woke up fast and had no shivering. She ate and went home one day later.

Isoflurane gas would be the choice anaesthesia in old dogs and cats. However, this cat was not very happy with her puncture wounds being poked around. As I did not want to stress her, I did not give her isoflurane gas direct during the first anaesthesia. Zoletil was sufficient for flushing of the flank. The process took a long time as I wanted to be thorough. Next time, flank irrigation could be shortened to 5 minutes instead of 15 minutes after debridement for old cats as they develop hypothermia easily.

In the usual cat bite wound cases, antibiotics and cleaning of the wounds would be sufficient treatment. In this case, the muscles were torn and infected deep below the skin. That was why the two puncture wounds produced a sero-sanguinous fluid daily and would not close. My vet assistant poured antibiotic powder onto the wounds as is the usual practice. The powder would just lodge deeper into the lower abdominal subcutaneous tissue and the wound just would weep again. The only effective treatment was to flush out the dead tissues rather than pour antibiotic powder so that the wounds would heal within 14 days.

Veterinary Performance counts in private practice. If the vet gives the owner a bottle of antibiotic powder and medication expecting the wound to heal, the owner would be much disappointed as such wounds would never heal. The owner would have wasted much time in putting powder clogging up the internal loose cavities of subcutaneous tissue destroyed by the bacteria toxins. In the end, the cat still needed surgery and the owner ends up paying much more.

This was not the simple case of cat bite wounds and the costs would be much higher as it involved two anaesthesias and surgeries. However, the clinical outcome was excellent. And that is what the owner wants - her cat's problems resolved in the fastest time.

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