Welcome to March's Case of the Month! Because of how busy things have become, we're going to have to reduce our cases to every other month for a little while. This month we look at a cat with an uncommon result of a cat fight.

 

WHAT'S IN THAT CHEST?

 

HISTORY

Copper was a mature cat (5 years old) who had developed trouble breathing. Over a period of several days, he'd progressed from breathing a little faster than usual, to breathing faster and harder than usual, to lying in one place and really fighting to breathe. He spent most of his time indoors, but frequently would sneak out for a few hours at night.

 

PHYSICAL FINDINGS

On examination, Copper was obviously having great difficulty breathing. He didn't move unless you forced him to, and always stayed in the same position, belly to the ground, with his neck stretched out. When we listened to his chest, several areas of his lungs sounded muffled. We took x-rays to evaluate his chest.

 

X-RAY RESULTS

first chest picture

Copper had an area of his chest obscured by fluid. For comparison, here's a more normal chest x-ray:

better chest

Here's a view with the fluid-filled area outlined in yellow:

fluid outlined

TREATMENT

We planned to draw a small amount of fluid off of Copper's chest to evaluate, and ended up removing about 8 ounces of fluid that looked like pus. Micoscopic examination showed no cells (which meant that it technically was not pus) or bacteria, making the fluid something called a transudate. This type of fluid has many possible origins, including damaged lymphatic ducts, heart disease, and cancer. Copper's chest had to be tapped several times over the next month to remove additional fluid.

Each time we removed fluid, we checked it under the microscope. By the fourth or fifth tapping, we were seeing a change in the fluid (it now was pus, so his condition was known as pyothorax) that suggested the presence of infection. A culture of the fluid revealed Pasteurella, a type of bacteria commonly implicated in cat fight infections. We put Copper on an appropriate antibiotic (determined by the culture results), and had to tap his chest a few more times. Eventually, almost all evidence of fluid had disappeared. The "normal" chest x-ray shown above was his chest after treatment.

DISCUSSION

When fluid appears in the chest, it can be very difficult to address. The chest itself is not easily affected by oral antibiotics, and there's no easy way to remove fluid (without inserting a needle very carefully and drawing the fluid off). Lung tissue can be scarred by long-term irritation from intrathoracic fluid, and some damage may be permanent. We'll have to keep a close eye on Copper for a while to make sure the infection is completely resolved, and to ensure he doesn't suffer any relapses. By the way, when we told Copper's owners that the type of bacteria we found was common in cat bites, they remembered him being in a bad fight with another cat just before his troubles started.

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