Commonly Used Medicines may Have Little Known Side Effects: Part 1
Most medicines prescribed by vets are safe. This means that they are not likely to cause serious adverse effects or toxicity.
Nonetheless, any time a pet takes a medicine there is a chance that side effects can occur, even if the side effects are not common.
Because of the risk of side effects, I try not to prescribe medications unless I have a solid reason to believe that they will help my patient. When I diagnose a condition that will resolve rapidly on its own without treatment, I prefer not to prescribe any medicine at all.
That sounds straightforward. But believe it or not, sometimes it upsets clients. Some people feel that they have wasted their time and money if they come home from the vet without some sort of medicine.
When a beloved pet is not feeling well, it is natural to want to do something about the problem. When people give medicine to their pet, they feel that they are helping their pet. However, if the medicine is not appropriate for the condition it may cause more harm than good.
Consider the following letter from a reader.
Hi, My baby Ginger just turned 8 this past
week and lately she has been coughing quite a
bit. It almost sounds croupey. She has an over-the-
counter allergy medicine that I give her and I’m
guessing she might have allergies. What do you
think I should do? (I’m planning to take her to
our vet this week, but I’d like your opinion.)
Allergies rarely cause coughing in 8-year-old dogs. Syndromes such as collapsing trachea, bronchitis, and heart disease are more likely culprits. It is unlikely that an over-the-counter allergy medicine will help much. (A trip to the vet, on the other hand, is exactly what I’d recommend.)
Over-the-counter allergy medicines (antihistamines) may cause sedation, agitation, or upset stomach. What’s more, they have been linked to some scary side effects in people. A number of studies have correlated the use of antihistamines (many of which fall into a class of medications known as anticholinergics) with cognitive decline (dementia) in elderly people. For an article that describes these effects in more detail, click here (warning: the article is somewhat technical in nature).
Some experts now recommend that people with familial histories of Alzheimer’s disease avoid over-the-counter antihistamines.
Animals do not suffer from Alzheimer’s disease per se. However, cognitive dysfunction and dementia appear to be common in elderly cats and dogs.
No link has yet been made between antihistamines and cognitive dysfunction in pets. Nonetheless, the brains and bodies of our pets are very similar to our own. In time a correlation may (or may not) be discovered.
Antihistamines have many valid uses in veterinary medicine. However, unless a pet has been diagnosed with a condition for which antihistamines are the appropriate treatment, I see no reason to give them.
You have questions. 
I agree. Many people are not aware of how harmful these meds can be. Good topic, Dr. Barchas
I don’t know if you’ve covered this before but I would also suggest a stern warning at giving pets medications meant for humans without clearing it first with their vets. I’m surprised at how often people do this.
Dogs & especially cats have different liver enzymes (cytochromes) that break down medications. Many can be toxic to pets that are perfectly safe for humans. And substances toxic to pets but not people can include herbs & various plant foods. People think nothing of feeding something like spaghetti to their pets.
Please write about medications, herbs & foods meant for people that are dangerous for their pets.
An article about the dangers of metacam in cats would be a welcome thing … I know it’s controversial. My cats all have “NO METACAM EVER” written on the front of their charts at the vet.
Allergic or hypersensitivity reactions are thought to be the most frequently occurring side effect. An estimated 3-10% of the general population are allergic to penicillin. Once an individual is allergic to one penicillin, he or she is most likely allergic to all of the penicillins. Those allergic to penicillin also have a higher incidence of allergy to the cephalosporin antibiotics.
Yeah I just recentlyheard you could use Benadryl on animals (Martha Stewart show). However I’d be hesitant to do so without knowing the proper amount for the size of the animal.
My dog got very ill to to metronitizole (Flagyl) overdose fighting giardia. He started falling down, acting like he was hallucinating and walking with a high step/prance. He’s a senior fellow and just could not tolerate the standard dose.
[...] most commonly recommended over-the-counter allergy medicine because it has a high margin of safety (although new concerns are arising about a link between Benadryl and cognitive decline in humans), and overdoses are rare. But in my experience, few pets derive much benefit from the [...]
We have two cats who have allergic rhinitis from time to time. The vet prescribed 1 mg (dropper-full) of either Benadryl or Dimetapp (children’s syrup) or half a Chlor-Trimeton tablet crushed & mixed with Nutri-Cal) for them (they each weigh around 10#). It seems to help them a lot, and outside of being sleepy (which they are most of the time anyway), I haven’t seen any bad side effects. I only give it to them if they start sneezing more than usual. Should I be concerned about giving this to them?
I have been giving my 8 yr. old Choc. Lab 2 glucosamine & chondrontin daily for his arthritic hips. Just recently started giving it to 8 yr. old male golden & 6 yr. old female golden. Spoke with my vet regarding this, and he ok’d it. Seems to be helping with any stiffness, but exercise does help as well. As we have a large fenced back yard, they do get theirs daily.
Any comments would be appreciated .
We have a old dog. Last week her ear was gving her trouble, so to the vet we went. She gave us Tri-otc 15g ointment. We used it 4 days and she can’t hear anything now. She is deff. Is this normal?
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BACKGROUND
Patches is a 14 year old male feline with a healthy history. In mid-February, 2008 he is showing some difficulty in his movements.
On February 29, 2008, he is diagnosed by Hudson Valley Animal Hospital, Valley Cottage, New York, with a chronic arthritic condition. Blood tests reveal borderline healthy kidney function. Otherwise he is in good condition.
He is given Metacam injection 0.3 mg/kg by Dr. Bridget Puzio at Hudson Valley Animal Hospital. Then oral Metacam 0.8 ml is given once daily for two days followed by 0.2 ml once daily every other day for two weeks. Never mentioned to the client at any time is the possible adverse reactions from the Metacam injection nor the FDA non-approval of oral usage in felines(see below for label warning).
Patches returns to the Hudson Valley Animal Hospital on July 25 after some of the arthritis symptoms returned. The other veterinarian, Derek A. Gadino, gives Patches a second injection of Metacam. Owner is not told of the possible adverse effects of the injection, nor told that a second injection is contraindicated on the Metacan label. In addition no blood testing is done to properly evaluate Patches’ current condition. Owner is not told of the reason or need for a physical exam or blood test; owner is not told the name of the drug injected in either visit; and the owner is never advised of the high risks of a follow-on Metacam injection.
Patches begins losing weight in mid-August with unusual sluggishness and increased vomiting, two weeks after the second injection.. He is barely eating, and on September 4 is brought to the Vet at the Barn and seen by Gloria Binkowski,VMD. She exams him , gives a blood test and reports that he has serious liver and kidney deterioration. After giving antibiotics and supplements to get Patches to eat, Dr. Binkowsi reports no improvement. Dr. Binkowski recommends Patches be given an ultrasound scan for a more specific diagnosis.
The scan done on September 10 shows major failure in liver, gall bladder, kidney, stomach, pancreas, peritoneum and lymph nodes. His ultrasound is done by Dr. Atkins at the Valley Cottage Animal Hospital and she states that he has chronic renal disease, pancreatitis, and cholangiohepatitis with dehydration and jaundice.. It is recommended that aggressive medical management be instituted with IV fluids, liver aspirate and e-tube.
On September 12, Patches is admitted to the Valley Cottage Animal Hospital. After two days of hospitalization, he is in organ failure, and is euthanized on September 15.
FROM THE METACAM LABELS AND INSERTS
“Additional doses of meloxicam in cats are contraindicated, as no safe dosage for repeated NSAID administration has been established. “. In black label, the insert states, ” Do not administer a second dose of meloxicam. Do not follow meloxicam with any other NSAID.” But, a second dose was administered, despite the warning. Also, in the Metacam Oral Suspension label, which is used exclusively for canines, there is an additional bold letter warning for felines, ” Do not use in cats.” However, the oral suspension was used and no warning given by Dr. Puzio for the off-label use.
” When administering any NSAID, appropriate laboratory testing to establish hematological and serum biochemical baseline data is recommended prior to use in dogs and cats. All cats should undergo a thorough history and physical examination before administering meloxicam. Do not repeat dose in cats.” No blood test nor exam was administered before his second Metacam injection.
“Foreign Experience: Repeated use in cats has been associated with acute renal failure and death. ” This severe warning, stated in black label, was ignored with the second injection.
“Information for cat owners. Meloxicam, like other NSAIDs, is not free from adverse reactions. Owners should be advised of the potential for adverse reactions and be informed of the clinical signs associated with NSAID intolerance…Cat owners should be advised when their pet has received a meloxicam injection.” In fact this narrow margin of safety with oral Metacam is reflected in the FDA’s Adverse Drug Experience for June 9, 2006 where the agency reported that in 320 felines, 105 suffered kidney failure, 48 died and 35 cats had to euthanized.. Despite these statistics and warnings, neither Dr.Puzio or Dr. Gadino ever mentioned that Metacam was used on Patches nor the significant health risk to him.
I am outraged by the the loss of my pet! I cannot believe I lost my cat because of this incompetence. I want to save other animals from this fate.
Addendum
By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com Date Published: 11/1/2004 10:46:00 AM
Date Reviewed/Revised: 11/12/2007
Side Effects
The side effects of concern are the same with all NSAIDs: stomach ulceration, loss of kidney function, and inappropriate bleeding. These are dependent on the dose of medication used and on risk factors of the host (for example: an aged pet may not efficiently clear a dose of medication from its body leading to stronger and longer activity of the drug). There is also a particular idiosyncratic reaction for NSAIDs that has received a great deal of press. An idiosyncratic reaction is one that is neither dose-dependent nor predictable by any apparent host factor; it simply happens out of the blue. This particular idiosyncratic reaction is a liver toxicity that is rare enough that it did not show up in any of the initial 400 carprofen test subjects, nor in the U.K., and was not recognized until carprofen was used in over a million dogs in the U.S. after its release as the first NSAID. This reaction is reviewed below. While originally it was carprofen use that led to the recognition of this reaction, it is now felt that all veterinary NSAIDs have potential to cause this reaction.
The most common side effects of meloxicam are nausea, appetite loss, vomiting or diarrhea. If any of the above are noted, meloxicam should be discontinued and the pet brought in for a liver enzyme and renal parameter blood test. In most cases, the reaction is minor and resolves with symptomatic relief, but it is important to rule out whether or not the patient has more than just a routine upset stomach.
If a patient has borderline kidney function, NSAIDs should not be used as they reduce blood flow through the kidneys(my underline). It is also important that NSAIDS not be given to dehydrated patients because of this potential side effect. This is particularly true in cats.
The hepatopathy side effect (usually occurs within the first 3 weeks of use).
[...] happens in veterinary medicine, as well. As I mentioned in my first and second articles on the little-known side effects of common medications, practicing clinicians [...]