Common Medication, Uncommon Side Effect: Emma’s Story

We’ve all seen those commercials—you know the ones. A woman joyfully frolicking through a sunlit field, praising a medication that changed her life. Everything looks perfect. But then, at the end, a voice speeds through a list of potential side effects like an auctioneer on a caffeine binge. My personal favorite? “Do not take [medication] if you are allergic to [medication].” Well, duh!

But here’s the thing—sometimes, the unexpected happens. And last week, I met a little Maltese named Emma who reminded me just how important it is to look beyond the obvious.

Emma’s Mysterious Decline

Emma, a 12-year-old spayed Maltese, had been diagnosed with kennel cough and prescribed Doxycycline—pretty standard treatment. At first, everything seemed fine. Her cough improved, but a few days in, her appetite took a nosedive. Concerned, her owner called her family veterinarian, who suggested that antibiotics sometimes cause mild stomach upset. They prescribed Ondansetron (Zofran) to help with nausea. But Emma still wouldn’t eat.

Ten days after starting the medication, Emma arrived at EVS Pet Urgent Care for lethargy and continued inappetence. Her physical exam? Mostly unremarkable. She was bright, alert, and responsive. No fever. Just an occasional dry, hacking cough when she got excited.

Digging Deeper

Something wasn’t adding up. We ran a full diagnostic workup, including:

✔ Complete Blood Count (CBC): Mild dehydration.

✔ Comprehensive Chemistry Panel (CHEM): Shockingly high liver enzymes—so high we had to dilute her sample three times just to get a reading.

✔ Radiographs: No masses or signs of cancer. A slight narrowing of her trachea, but nothing definitive.

At this point, I had to be honest with myself—my biggest worry was cancer. Emma was 12, after all. But as I always remind myself: age is not a disease.

Yet something still felt off. Cancer in the liver typically causes gradual decline—weight loss, vomiting, diarrhea, and jaundice. Emma had none of that. Her owner kept insisting, “She was perfectly normal before the antibiotics.”

The Power of a Good History

My dad, a physician, always told me, “99% of a diagnosis is in the history.” He was right.

Could it be the Doxycycline? At first, it seemed absurd—Doxycycline is used all the time, even in babies! But then, that fast-talking commercial voice popped into my head again: “Do not take Doxycycline if you are allergic to Doxycycline.”

A quick search later, and there it was:

📌 According to the National Library of Medicine, “Doxycycline… has been linked to rare instances of acute cholestatic liver injury.”

📌 A veterinary article confirmed: “Doxycycline occasionally causes increased ALT and even icterus… It is very important to recognize the possibility.”

Emma’s case fit the pattern.

The Road to Recovery

To rule out other causes, further diagnostics were performed including an abdominal ultrasound. Everything else came back normal. With supportive care, Emma made a full recovery.

Trust Your Gut

The lesson here? Pet parents, trust your instincts. You know your pets better than anyone. If something feels wrong, speak up. Advocate for them.

And to my fellow veterinarians—never stop questioning. Medicine isn’t about always having the right answer; it’s about being willing to find it.

Emma’s story is proof: even the most common medications can have uncommon side effects. And sometimes, the best diagnosis comes from simply listening.