Adverse Drug Reactions in Dogs: Our Dogs’ History of Adverse Reactions to Medications

Unfortunately, we are no strangers to dealing with severe side effects and adverse drug reactions in dogs.

It doesn’t come as a surprise that I have a love-hate relationship with medicating your dog. Perhaps more hate than love. Yet, drugs do have their place and there are times when they can be life-saving. I medicate very conservatively; if there is an alternative option, I’ll consider it first.

Adverse Drug Reactions in Dogs: Our Dogs' History of Adverse Reactions to Medications

Drugs don’t come without side effects.

Regardless of a safety record a medication might have, be aware that your dog could be the exception and react badly.

It is my experience that veterinarians rarely volunteer this information and getting it is sometimes like pulling teeth. Be prepared and armed–grab my Veterinary Visit Checklists. Armed with the checklists, you will never leave a veterinary office without any important information.

Some side effects are more common than others. The rare adverse reactions can be quite severe. Experience has taught me to study the product sheet for any medication I give my dogs. I both ask the prescribing vet and research how common some of the serious side effects may or may not be.

Adverse reactions versus side effects

If you like to split hairs, there is a technical difference between side effects and adverse reactions. The main difference between the two is that side effects are documented while adverse reactions unforeseen events.

Adverse events are unintended pharmacologic effects that occur when a medication is administered correctly while a side effect is a secondary unwanted effect that occurs due to drug therapy.

Pharmacy Times

Do I care about the semantics? Not when documented side effects include things like seizures, kidney failure, or death I don’t. Documented or not, my dog could get hurt just the same. And, yes, if you dive into drug information sheets, you will find plenty of horrible effects listed. They might be rare but they can happen.

Side effects are a necessary evil?

Jasmine’s vet used to say that a drug with no side effects is a drug that won’t do anything else either—is useless.

To this day, drugs are imperfect in a way that they affect things other than those they target. NSAIDs, for example, inhibit enzymes involved in inflammation. However, those very same enzymes have other jobs that get inhibited in the process.

Most common side effects of any oral medications are digestive disturbances because it is the digestive system that has to process and absorb them.

Drugs are like carpet bombing—there will be casualties. The day when scientists develop medications that will do only what they are intended to is yet to come. By then, though, we might find a completely different, better way of healing.

And then there is the potential of an allergic reaction to any substance.

The need to medicate

For the time being, sooner or later your dog is likely to need drugs.

There was a time when I didn’t think twice about it. A veterinarian prescribed medication, I gave it. I figured that if there was something else I should know, they would tell me. How often does your veterinarian educate about potential side effects of the drugs they prescribed?

Common side effects

For a long time, we didn’t have any problems with meds, other than upset stomach or diarrhea.

The top common side effects of veterinary medications include:

  • vomiting and diarrhea
  • stomach ulcers
  • skin reactions
  • lumps and bumps
  • lethargy
  • weakness
  • liver or kidney damage
  • anaphylaxis

Source: petMD


Jasmine and NSAIDs

Adverse Drug Reactions in Dogs: NSAIDs

When Jasmine was prescribed NSAIDs for her arthritis, I did ask what side effects we should be watching for. “The usual,” I was told. “Vomiting, diarrhea,”

Jasmine was on it for a couple of days when she stopped eating. Except, it wasn’t all that unusual for her. She would get like that every now and then.

I didn’t get worried until she stopped drinking as well. That has never happened before. Can you guess this happened over the weekend? I had nobody to talk to about what was happening.

Fortunately, since this problem was new, I figured that it might be caused by something newly introduced – Jasmine’s meds. I went online to learn about side effects and I almost got a heart attack at what I was finding.

I have immediately stopped giving it, trying to decide whether we needed to take Jasmine to an emergency clinic or not.

Adverse Drug Reactions in Dogs: Previcox information sheet
Here is what the product sheet had to say about potential side effects:

Previcox, like other NSAIDs, may cause some side effects. Serious side effects associated with NSAID therapy in dogs can occur with or without warning, and, in rare situations, result in death.
The most common side effects associated with Previcox therapy involve the digestive tract (vomiting and decreased food consumption). Liver and kidney problems have also been reported with NSAIDs. Look for the following side effects that may indicate your dog is having a problem with Previcox:

  • Decrease or increase in appetite.
  • Vomiting.
  • Change in bowel movements (such as diarrhea, or black, tarry or bloody stools).
  • Change in behavior (such as decreased or increased activity level, incoordination, seizure, or aggression).
  • Yellowing of gums, skin, or whites of the eyes (jaundice).
  • Change in drinking habits (frequency or amount consumed).
  • Changes in urine and urination habits (frequency, color, or smell.)
  • Change in skin (redness, scabs, or scratching).
  • Unexpected weight loss.

It is important to stop the medication and contact your veterinarian immediately if you think your dog has a medical problem or side effects while taking Previcox tablets.

Needless to say, I was freaking out.

Jasmine made it through the ordeal without any serious lasting damage. But it was an eye-opener for me, and, as it turned out, for Jasmine’s veterinarian as well.

It was the first time we had a scary reaction to meds. Suddenly, the advice to watch for the usual (vomiting or diarrhea) was not good enough. The more I was reading all kinds of horror stories posted regarding the particular NSAID Jasmine was put on, the more I was freaking out.

Precautions when giving NSAIDs

If your dog is on NSAIDs and gets ill, stop giving it immediately and see a vet.

It was Sunday, of course, all horrors happen during weekends, don’t they? The main question was whether the situation was dire enough to run Jasmine to the emergency or whether it could wait till Monday. Jasmine wasn’t getting worse and by the end of the day I was able to get her to drink some chicken broth “shake”.

Monday morning, after sending a lengthy email describing everything in detail, I was on the phone with the vet. He agreed we should bring her in, have her checked out and run blood work. Ruling out other causes, the NSAID came as the highest suspect. Particularly since things improved quickly once I stopped giving it. The vet himself used the words “an eye-opener.”

Many dogs benefit from the use of NSAIDs and have no issues.

JD had them a few times and even Cookie did. They worked well and neither JD or Cookie had any adverse effects. I accept their use as a short-term crutch when quick pain and inflammation relief is needed. I would not use them long-term. Because Jasmine could not have any NSAIDs for the rest of her life, I quickly learned about all the available alternatives. There are many great options out there. For long-term management, those are my go-to solutions.

A note on using NSAIDs safely.

There is the right way of using NSAIDs and there is the wrong way.

To lower potential adverse reactions, proper screening needs to be done. That includes a medical history and blood work to make sure that kidneys are healthy and working properly. Though that doesn’t mean thing cannot go wrong. Jasmine did have fresh blood work and everything was in order. However, I would not start my dog on NSAIDs without having blood work that is no older than a month.

Never give NSAIDs on empty stomach. They have to be given with food. Also, when Cookie was on relatively long-term course for her iliopsoas injury, we used stomach protectant as well.

Never mixed different NSAIDs. That also means aspirin and/or Tylenol. If you did give any of these to your dog prior to the vet visit, let your vet know about it.  If switching between any two different NSAIDs, allow for “wash-out” period. This is the time it takes for all the drug to be cleared from the body. A recommended wash-out period is three to seven days.

If you’re giving any other medications or supplements, make sure your veterinarian knows about it.

If you suspect your dog is having side-effects, stop the NSAIDs immediately and talk to your veterinarian.

When in doubt, ask, and ask, and ask again.

I also recommend getting the product safety sheet and reading it thoroughly. Many of the scary, serious side effects are very rare but you want to be aware should you run into them. Figuring out what is happening quickly allowed me to stop the medication and prevent further complications.

Luckily, our first experience with adverse drug reactions didn’t end up in any major disaster, just a big scare and a wake-up call. It could have, though.

It also meant that Jasmine could not have any type of NSAID, ever. That became quite a useful exercise in finding alternatives to manage her pain whether from arthritis or from injuries, surgeries and anything else under the sun.

Paired with her food allergies, which also dramatically limited our choices of supplements, it was quite a work-out in researching and finding solutions.

We also became extremely careful about any medication she would be given. I never looked at a bottle of meds the same.


Jasmine’s drug-induced hyperthermia

Adverse Drug Reactions in Dogs: Drug-Induced Hyperthermia

With all the precautions, little we realized we were in for much bigger disasters to come. And we did not expect one when we just took Jasmine for x-rays.

Her episodes of panting, pacing, and general distress were becoming worse and more frequent. Having considered and ruled out many options, it was decided to x-ray her heart and lungs to see whether the problem was there after all. What didn’t occur to us that she would come so close to not coming back home to us from that.

Hubby dropped her off at the vet and went running some errands. It was supposed to be a couple-hour deal; quick and easy.

Instead of getting a call that Jasmine was ready to be picked up to go home, he got a call that Jasmine suffered severe hyperthermia, and they were going to keep her until they can get her stabilized. What???

As Jasmine was coming from her anesthesia, she seemed in pain. This can happen from the manipulation needed to get the right images. It was only logical that her vet gave her a shot of pain med to get her comfortable. It was the pain med, Buprenorphine, that triggered her hyperthermia. Her temperature spiked. There is an antidote which they gave her to reverse it. It took quite a while to get her temperature back to normal.

That day we almost killed our dog.

Technically we didn’t do it, but we brought her in for the x-rays. And everything else happened from there. Jasmine was in very bad shape. Once stabilized enough, it was decided that she’d go home where she’d be happier and more comfortable. She looked terrible, barely able to walk at all. Could only get up with help and needed support while walking otherwise she kept stumbling and falling.

They told us that she should improve by morning. We all slept on the kitchen floor with her for moral support and also to be able to help her if she needed anything. We were all awaiting the morning when she should be feeling better.

But she wasn’t better, she was worse.

With a lot of help, she barely made it to potty and when she peed her pee was brown!

She also had bruising on her tongue and belly. We immediately took her to an emergency vet where further horror unfolded. I wrote about that already.

This little adventure fried her muscles, fried her liver and fried her platelets. It bought her a week stay in ICU in our teaching hospital and a month of recovery before she was back to normal.

What the heck happened?

It was conclusively determined that the Buprenorphine triggered all that. It was not, however, determined why. There were reports that this drug can cause hyperthermia in cats but it is unheard of in a dog. There was nothing in her history or blood work that would predict a problem with this drug. And yet it almost killed her.

This was beyond any wake-up calls. This was living in a twilight zone.

If I was being careful with meds after Jasmine’s adverse reaction to NSAIDs, I became right down paranoid after the horror caused by the Buprenorphine.

It almost killed her and cost her a week at ICU and a month of recovery.

Strangely, as a wild twist of fate, it also likely saved her life but I wouldn’t consider that a standard rule for drug adverse reactions.

Being as careful as we became and opting for non-drug solutions every time we could, we had a few years free of medication-related horrors. Jasmine’s file had two red stickers on it – no NSAIDs and no Buprenorphine.

There were a couple of occasions when I almost got talked into putting Jasmine on steroids but I persevered and we handled things without them.


Jasmines reactions to morphine

Adverse Drug Reactions in Dogs: Morphine

Everything was fine until Jasmine’s neck, which has been a ticking bomb all along, blew.

That fall, she was doing amazingly well. Vibrant, vital, full of life, she looked like she had at least two more full years in her easily. And then, without any warning, she became a train wreck. At first, I had no idea what I was looking at. All I knew was that something was very wrong.

That was the day I agreed to steroids.

If there were a time and place to use them, that was it. Jasmine was in terrible pain and needed relief fast. She got steroids as well as a shot of morphine.

She looked pretty horrible but given her diagnoses, it would have been expected. It took a couple of days for her to start feeling reasonably comfortable. Obviously, she was on strict exercise restrictions; just the fact she didn’t really care was a sign she was in a lot of pain.

Slowly, she started being able to go outside for short, easy walks. At the same time, it was determined she needed her dental done. As soon as she looked like she got over the “neck event”, it was scheduled, bearing taking high precautions to minimize neck manipulations during the procedure. Her lower front teeth, that had been slowly declining reached a point when they needed to come out. The surgery went smoothly; she returned home with medications and another shot of morphine.

Something wasn’t right, though.

She was anxious, trying to pace around, while at the same time barely able to stand. Both her wrong and back were extremely “droopy.” She needed to lay down and rest but she couldn’t/wouldn’t no matter how hard we tried.

It didn’t really look like pain from her neck. It was suspected that she wasn’t dealing with the anesthesia as well as she used to. The solution was letting it get out of her system. You can only imagine how sorry I was that I agreed to do the dental, however much it needed to have been done.

And yes, she had fresh pre-op blood work and the protocol used was the same one she never had issues with before.

In my mind, I have decided not to even put her through anesthesia again.

She bounced back in about 24 hours. She got weaned off the steroids and started enjoying longer and longer walks. Things started getting back to where they should be. We were extremely careful with her and we did have some challenges and setbacks, but overall things looked pretty good. It seemed that she was going to be okay once again.

Until April.

When Jasmine got her first-ever UTI, it wasn’t a big surprise. With any kind of mobility challenges, it can happen easily. It got treated and went away. But only to return. To do things properly, we ran a culture and found out that this time around she had a resistant strain. The choice of antibiotics to which this strain would respond to was limited to a few nasty options.

Even though the least nasty antibiotic was selected, the effects from it were severe.

Jasmine was nauseous, didn’t want to eat, and Cerenia barely made a dent in that.

I was on the phone with her vet, discussing all this, trying to see how we can help her get through this. Not five minutes after we hung up, I was on the phone again.
“Dr. Rae wants to know what has changed in last five minutes,” the receptionist asked. Yes, I realized we just talked for half an hour.
“A lot has changed,” I answered, “Jasmine got up.”

Jasmine got up and it was very obvious that her neck had another major setback. We were on our way.

Jasmine got another shot of morphine and was put on steroids once again.

What followed made it clear that it wasn’t the anesthesia but the morphine what made her so miserable after her dental.

Morphine, which was supposed to be her friend, became her enemy.

You can see here what shape she was in. This time she was not getting better but worse. On top of all that, her liver was now enlarged and painful.

Those were her last days. Between the steroids, nasty antibiotic and the morphine, her body was unable to cope any longer.

Regardless of how Jasmine’s last days played out, she needed those meds. They were supposed to help her. There was no way of knowing what was going to follow. I was concerned about the steroids, but there was no doubt she needed them. I was extremely concerned about the nasty antibiotics, but the one we used was the most gentle of the available bunch. The morphine was perhaps the last straw, but she was in extreme pain …

Did I become more cautious?

I couldn’t get more conservative with medicating my dogs because I have been extremely conservative already.

Every time I might need to medicate my dog I consider other options first. If drugs are deemed unnecessary, the vet(s) and I discuss whether or not there are more than one option to choose from and which would be least likely to cause problems. Then I read the product sheet carefully to see what I might expect.

Wherever I can, I opt for a non-drug solution.

But sometimes that is either the best or the only option.


Cookie’s adverse reaction to Advantix

Cookie's Adverse Reaction to Advantix

Cookie is a hunter at heart. She’s a bush dog. She will go where no man has ever gone. One time she came back from the farm with three ticks on her face.

Jasmine was a hiker and was always content exploring the world mostly walking on trails. JD was a follower and would just go whether everybody else did. Cookie, however, has to go where the critters are, which rarely involves paths or trails.

With ticks slowly taking over the world and Lyme disease and other tick-borne disease becoming a bigger and bigger concern, we had to consider how we were going to protect Cookie.

After a lot of discussion and deliberation considering efficacy and safety, we have chosen Canine Advantix.

At the time it was the best and most effective option. Plus it’s supposed to also work against mosquitoes, biting flies and lice.

It is applied topically. The first time Cookie was a little bit upset as if it was making her itchy. Her reaction was mild, and we figured it might have been the sensation of the drops on her skin. It didn’t last long. The next time, though, she was acting as if attacked by fire ants. She was obviously miserable, and it wasn’t getting better but worse.

We quickly washed it off with dish soap, then all of her with her shampoo and rinsed and rinsed. Shortly after we got it off her, she calmed down.

I talked to the vet, and she said that sometimes it might make the skin feel numb.

Interestingly, the product label is pretty vague about that. The side effects listed are skin irritation such as redness, scratching, or other signs of discomfort. It also states that vomiting or diarrhea have been reported, and if those or other side effects such as lethargy occur to consult a veterinarian.

There was no redness or visible irritation of the skin, but there was no question we weren’t going to use it again.

Not a really big deal as far as drug reactions are concerned, I suppose, though Cookie would not agree.

What would happen if we didn’t know what to do or did nothing?

With any of these things, it is always a question of lesser of the evil.

But sometimes that can be really hard to determine.

Like most of you, every time my dog requires anesthesia, I’m concerned. Not because of Jasmine’s dramatic reaction to the Buprenorphine; that is so rare it is really unheard of. And not because of the events towards the end; who knows what crazy factors were at play.

JD’s reaction to anesthesia

Adverse Drug Reactions in Dogs:: JD's Anesthesia Effects

There is always some risk with anesthesia.

Anesthesia protocols have come a long way and became much safer. Proper monitoring during and post-anesthesia are also crucial, but our vets do all this thoroughly.

Issues can always crop up, though, whether with anesthesia or with sedation.

JD, for example, seems to take anesthesia quite hard. He never had what you’d call a true adverse reaction, but he had a very hard time coming out of the effects the last two times. I tried to discuss that after the first time but it didn’t look anybody revised his protocol.

While is generally accepted that small and/or brachycephalic dogs are the ones most likely to have a hard time with going under, as it turns out, large dogs can have some issues as well. For reasons having to do with their metabolic rate, the biggest challenge with large and giant breeds is the dosage. As it seems, pound-per-pound, they require a lower dose than small breeds.

I think that’s what was behind JD having a hard time getting over his anesthesia.

It seems that calculating the right dose can be quite tricky. There are other breed considerations. It is important to make sure your veterinarian understands what is the best protocol for your particular breed.

Cookie's Adverse Reaction to Sedation

Cookies adverse reaction to sedation

Cookie, on the other hand, had a major reaction to sedation.

While there might have been other factors at play, I insisted that Cookie’s protocol was carefully reconsidered. The next time, with a different protocol, Cookie had no issues at all.

There is never a problem until there is.

When it comes to medications for your dog, it is important to be mindful of potential adverse effects. It can be one pill or one dose that causes trouble. But it can be a medication your dog was on for a long time and handling it well. Just because there was never a problem before, it doesn’t mean bad things can’t happen.

Always review the product sheet for any medication you’re about to give your dog.

Learn what you might expect and be ready. If all goes well, you can sigh with relief. But if something should happen, you’d be prepared.

Categories: Adverse reactionsConditionsReal-life Stories

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Jana Rade

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience.

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