Diarrhea resolves with Cephalexin.

Dear Dr. Marie,

I’ve been in the throes of a medical mystery with my beloved dog, Cori. Any intuitions or thoughts would be more than appreciated.

About four years ago Cori, my 65-pound white terrier mix, then 6 years old, came down with a fungal skin infection that produced pustules chiefly along her stomach. At first my veterinarian recommended just a medicated shampoo, Sebezole, twice a week, for a month. The blisters could not be maintained without the shampoo and eventually began enlarging – sometimes the size of a walnut. Cephalexin, 500 mg, twice a day, was prescribed.

For a year and a half we struggled with a regimen of Cephalaxin, on and off, Sebezole baths twice a week and eventually some sort of injection that was expensive and used just twice. Eventually the blisters healed!

However she began showing bouts of watery diarrhea that would last weeks and could not be controlled without metronidazole. She had no fever, no loss of appetite and no vomiting. Additionally we tested for parasites and did two rounds of Panacur to make sure.

Metronidazole became a life saver. After about every 9 pills (1 and 1/2 twice a day, 3 days), her digestive system would stabilize for a week to two weeks. After about two years of this she began straining to urinate multiple times throughout every walk. Blood work showed only mild liver dysfunction and no UTI. The veterinarian believed her stomach was slightly tenser than it should be. The long-term use of metronidazole was suspected as the culprit and I was told there was no alternative.

After some persistence and experimenting I discovered a certain high quality probiotic that worked wonders for about two months before the relentless diarrhea returned. Pepto-Bismol, to coat the stomach, doesn’t really help at all. Loperamide only helps moderately, and appears to produce some discomfort for her every time – after taking it, she will often refuse to eat for a day or two, when otherwise her appetite is excellent. And the benefits of the Loperamide appear to diminish over time.

I struggled with this routine of probiotic, Loperamide and Pepto until the skin infection returned recently. It was a very mild outbreak and Cephalexin cleared it completely.

But to my surprise, the Cephalexin completely fixed her digestive issues too. While on the 14 day prescription, every stool sample was completely normal. After finishing the prescription about a week ago, the severe diarrhea returned today.

Is there some connection the veterinarians I’ve consulted don’t understand? Could there be a bacterial infection in the intestines that somehow responds to the Cephalexin? My veterinarian said I could try another round of the Cephalexin to see if the results return or even last – does this make sense? If the long-term Cephalexin from those years ago simply irreparably damaged the balance of the flora in the colon and intestines, why would using the Cephalexin now produce completely normal stools for a short period of time?

I’ve consulted everyone I can on a local scope.

Thank you for taking the time to read about us.

Kind regards,

Richard and Cori