Dear Most Esteemed and Knowledgeable Kitties:
A couple of months ago, my 9-year-old male cat became quite ill. His symptoms were primarily lethargy and decreased appetite. We took him to the vet where his blood work revealed an elevated neutrophil count, but his white blood cell count was otherwise normal. The vet prescribed antibiotic prophylactically. Now my cat’s immediate symptoms are resolved, but he is left with what seem to be neurological problems including balance disturbance and pupils oddly dilated. I’m concerned that he may have mercury poisoning as I have given him tuna on a regular basis. Are there diagnostics and treatment for that? Do you have any other ideas of what may be going on with him?
~Jane
Siouxsie: Our research indicates that while an occasional tuna treat is okay, there are a number of hazards to regularly feeding tuna to your cat.
Thomas: Too much tuna can lead to vitamin E deficiency, resulting in yellow fat disease, or steatitis. Symptoms include loss of appetite, fever and hypersensitivity to touch due to inflammation and necrosis of fat under the skin.
Dahlia: Cats that eat too much tuna can develop other nutrient deficiencies, because most de-boned fish doesn’t have enough calcium, sodium, iron, copper, and is also lacking in several other vitamins.
Siouxsie: The high levels of mercury in tuna can be dangerous, too. If tuna is fed occasionally, it’s not a big deal — but if you feed him tuna every day, you could be risking mercury poisoning.
Thomas: So what are the symptoms of mercury poisoning? According to the Merck Veterinary Manual, signs of mercury poisoning in cats may include over-excitement, irritability, incoordination, convulsions, stiff hind legs, tremors and blindness.
Dahlia: Mercury poisoning is pretty rare in cats, and in people. It is usually diagnosed by a blood test or a test of the hair/fur.
Siouxsie: If a diagnostic test indicates that your cat has mercury poisoning, a therapy called chelation can be done to eliminate the mercury from his body.
Thomas: So, if your cat is suffering from mercury toxicity, it can be treated. But now we’re going to tell you about one of our favorite axioms, the Horses, Not Zebras Theory. Basically, Horses, Not Zebras says that if you hear hoofbeats outside your window (and you don’t live on the African savanna), it’s much more likely to be a herd of horses than a herd of zebras.
Dahlia: In short, the cause of your cat’s symptoms is likely to be something much more common (horses) than mercury poisoning (zebras).
Siouxsie: If your cat didn’t start showing neurological symptoms until after he began his course of antibiotics, the symptoms may be a side effect of the medicine.
Thomas: This is still a bit on the zebra-ish side, because very few antibiotics have neurological side effects, and even for those that do have known neurological side effects, the incidence of these effects is incredibly rare.
Dahlia: The fluoroquinolones are powerful antibiotics that are commonly prescribed for pets. The most widely used fluoroquinolones are enrofloxacin (Baytril®), ciprofloxacin (also known as cipro), orbifloxacin (Orbax®) and marbofloxacin (Zeniquin®).
Siouxsie: They are used to treat infections of the skin, bladder, ears, kidneys, lungs (pneumonia), and prostate gland. A liquid solution is also made in the form of ear drops to treat ear infections.
Thomas: In very rare cases, cats receiving high doses of Baytril® have developed severe, irreversible vision problems. Researchers believe this adverse reaction is unlikely at lower doses, though.
Dahlia: Mama says Thomas had to take Baytril® before, when he was a wee, sick shelter kitty, and he’s just fine! Sinéad had to take it a few times for UTIs, and she never had any neurological problems as a result.
Siouxsie: For more information about fluoroquinolone antibiotics and side effects, check out this page on noted veterinarian Dr. Eric Barchas’s website.
Thomas: This page at vetinfo.com has a list of side effects of common veterinary antibiotics used on cats.
Dahlia: Jane, you really need to get in touch with your vet and let them know that your cat is having these symptoms. Whether it’s mercury, an antibiotic reaction, or something else entirely — only your vet will be able to solve the mystery.
Siouxsie: Please keep in mind that this information is not in any way intended to be a diagnosis. Even if we were licensed vets, we’d never make a diagnosis without seeing your cat and performing diagnostic tests!
Thomas: However, we hope we’ve helped you to know what questions to ask your vet when you take your cat back to the clinic.
Dahlia: Good luck, Jane. Please let us know how things turn out.
JaneA Kelley is a punk rock cat mom and award-winning blogger. She is a regular columnist for Catster Magazine, and she and the Paws and Effect Gang share a home in the beautiful Pacific Northwest.
Interesting. I’ve never fed my cats a ton of tuna, but sometimes let them lick the leftovers in the can. I think some people assume it is natural to feel cats tuna — this is very informative!
Hi i have just discovered that a motel behind my house has dumped tons of florescent tubes in between my house and their back yard… I have had to take both my cats to the vets in the last 3 weeks because they have lost their voices and their throats are swollen, they have been treated and are doing better but one still does not have his meow back as of yet.. Do you think there is a connection to mercury poisoning? i will be contacting their vet in the morning and also calling out the city for illegal dumping. pls let me know if this is a possibility. thank you very much
My cat demands tuna and has been eating it every day for some time in addition to James Wellbeloved dry food. I have noticed that he sometimes prefers to climb the chair arm rather than jump these days and has also objected to being touched on his back legs at times. Its going to be hard to get him off the tuna habit as he is very vocal but I think I need to cut down to maybe one day a week treat and see if he becomes more agile. I went onto tuna as an alternative to prawns as they were expensive but they might be a more satisfying once a week treat.
Recently I was diagnosed with mercury poisoning, probably from my having eaten 7-8 cans of tuna per week over a period of nine months (I was exercising vigorously, but didn’t want to include red meat in my diet, so tuna seemed a good alternative…). My symptoms were quite severe. I’ve mostly recovered now (with patially numb hands and tinnitus that may never go away); but as I look back I realize that 15 years ago, my then also serious health issues were caused by excessive tuna consumption. At the time, I also regularly fed my cat tuna. Every can I ate, I shared with my cat. And my cat also developed bizarre symptoms: within the space of a few months, every one of its teeth became loose and fell out, and it produced excessive saliva. Symptoms of methyl mercury poisoning are many. If you are feeding your cat lots of tuna, then the sound of the hoofbeats is probably coming from a horse called tuna.
P.S. My own severe symptoms included seizures, heart arrhythmia, severe fatigure, fainting, irritability, hand tremors, burning red hands and feet, pain in my lower jaw and teeth, and peeling skin on my hands and finger tips. All that just from tuna! And my cat was only 2 years old when its all teeth fell out.
I would like to know after reading this article and searching for days just exactly where I can find anyone in the Boston area who can help my cat resolve what I know is mercury poisoning because of me his stupid owner…..couldnt resist giving him albacore tuna every time I ate it… not knowing the hazard behind it…. Ive called poison control ive called animal poison control ive tried angel memorial…. metro cat and even tried calling around… the only thing I was able to get done was active charcoal… IDK if that took care of it he still seems not himself?!!
Sadly, I just lost both otherwise healthy cats (12 and 9 y/o) within a period of 4 months. Symptoms were lethargy and weight loss with slight imbalance toward the end. I had been feeding them canned tuna (always mixed with canned chicken, canned cat food and pureed baby food vegetables (green beans, pumpkin or squash) for about two years. They never showed signs of pain. They both died within about 3 months of their first symptoms of weight loss. I had a mercury blood level drawn from the younger cat but the sample was drawn two weeks after stopping the feeding of canned tuna, results were inconclusive. I’m upset that I never was warned about feeding them canned tuna after routinely reporting what I was feeding them.
I started giving my cat tuna can tuna for about three months every day all day and I noticed he start getting scabs around his neck really bad do you think he has mercury poisoning