Unknown Cause of Fever and High White Blood Cell Count

My dog has been sick for the last 2 weeks (Almost 3 weeks), in and out of the vet. No one knows what is wrong with him. He has been having a low grade fever to a high fever these past 2 weeks. His wbc was normal in the beginning and last week it went up to 50,000. He's on a bunch of different antibiotics and now it's up to 71,000. Any idea what would be causing this?

Hello - high white blood cells can suggest that inflammation is going on somewhere in the body.   They can also indicate infection somewhere in the body, or cancer, such as lymphoma.  There are also some conditions called auto-immune diseases, whereby animals seem to mount a white blood cell response to their own body.  Pancreatitis may be a strong possibility, at any age - it is an inflammation of the pancreas that frequently causes sickness.  Pyometra (a womb inflammation / infection) presents like this commonly in females.   Because most of these problems would not be solved using antibiotics (and because of antibiotic resistance), it is usually recommended that antibiotics are given only when specific signs or types of infection are known to be present.  Good questions for your vet in order to understand this case better, may be:  what are the possible causes of this presentation?  Which causes are likely?  How can you start ruling things out?  Meanwhile, what treatments might help?  Wishing you the best of luck with this case and please do let us know how this patient gets on.   Pyrexia (high temperature) can be caused by pain or stress as well as by infection.

Wishing you and your boy all the best and we hope that some of this information is helpful.