Cadence the Cat: The case of the lethargic cat

Patient is a spayed female 1-year-old domestic short hair feline (cat). The owner brought the cat in because she had not been eating and was very lethargic.

What are some important questions to ask about the patient’s history?

  • When was the patient’s last regular meal?
  • Is it an indoor or outdoor cat?
  • Has it been vaccinated?
  • Is it on flea/tick preventative?

The owner explained that they had not had a chance to put any flea/tick product on the cat. It was a barn cat and sometimes hard to catch. Cadence has had several ticks on her and the owner wasn’t sure when she had eaten last. Never vaccinated.


I examine Cadence and notice that she is very icteric (yellow) around her eyes, ears and mouth. She is not moving around much, which is very strange for most cats during an exam.

Cadence’s temperature is 106.0 Fahrenheit. A cat’s temperature should be between 99.5 and 103.5. Her gums are icteric (noted earlier). Her respiratory rate was slightly increased and a few ticks were noted around her rectum. The rest of her physical exam was normal.

With these clinical signs in mind, I start thinking of differentials:

  • Parasites
  • Viral
  • Bacterial

Cytauxzoon felis


As with most of my cases that we have reviewed so far, it is always important to run some diagnostics. At this point, because I see way too many cases of this very same thing, I can pretty much tell you exactly what is wrong. But, as I tell my clients, I love it when I am proven wrong, especially in these cases because the outcome is never good.

The biggest worry I have is that this is a tick-born disease that acts very quickly and not treatable. I want to draw some blood from Cadence to test her for Cytauxzoon felis, also called Bobcat Fever. The blood is put on a slide, stained and looked at under a microscope. The pathologist is looking for what’s called piroplasms, which you can see in the picture (the small dots in the red blood cells).

Life cycle of Cytauxzoon felis.

This test usually takes about 24 hours to get back (for our clinic anyway). Because I want to rule out other causes of the pyrexia (fever), I am also going to run a few more tests:
FeLV/FIV Test: Feline Leukemia Virus and Feline Immunodeficiency Virus can also cause cats to be lethargic and run a fever.

Fecal: Most intestinal parasites are not going to cause a fever, but if Cadence has a lot of parasites this can lower her immune system and she won’t be able to fight off disease as easily.
CBC/Chemistry: A complete blood count is very important in order to determine if Cadence has an infection or not. A chemistry panel will allow us to look at her liver, kidney, protein, and electrolyte values to see if there are any clues that lead us to a different diagnosis.

These tests all came back negative, which makes me worry even more that this is C. felis.


Every veterinarian is going to have their own protocols for managing/treating various diseases. Because I am waiting on test results to come back on Cadence, I begin to provide her with supportive care.

  • Fluids to help lower her fever, but careful to not lower her fever too quickly
  • Antibiotics are started to prevent secondary infection
  • Nutritional supplement
  • Provide topical flea/tick preventative
  • Antivirals if available


Unfortunately for Cadence, her test results came back as positive for C. felis. She was progressively getting worse, and the owners opted to humanely euthanize.


C. felis is a deadly disease and currently not treatable. Although there have been a few cases out there that have survived, it is rare. Intense research is being done to discover how we can treat this in the future and possibly prevent it.

One method of prevention is to keep a good flea/tick product on your cat, especially if it is an outdoor cat. Check your cat daily for ticks and remove any and all that you can.
Keeping your cat indoors is still the best prevention.

To find out more about C. felis and it’s lifecycle,
visit this link.

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