It started out as a routine visit. Lili, a 14-year-old Labrador retriever, was taking prescription NSAIDs for arthritis. NSAID is an acronym for non-steroidal anti-inflammatory drug, i.e., medication that does not contain steroids (like cortisone) but reduces inflammation, and, hence, pain. This common group includes drugs like ibuprofen (for people, not for pets), and such veterinary medications as Rimadyl, Deramaxx, and Metacam, to name a few. These drugs can make a huge difference in the day-to-day quality of life for elderly animals, but those getting frequent NSAIDs should have blood work monitored every six months or so to make sure kidneys and liver are functioning well. That’s why Lili came to see me. Just routine … but when the tests were completed, there was evidence of mild kidney dysfunction. “Lili is in Stage II chronic renal failure,” I told her owners. “We need more information. Can you bring a urine sample?”
Chronic kidney disease (CKD) is defined as irreversible, progressive loss of kidney function persisting for at least three months. Now I didn’t know if Lili’s problem is “chronic,” but based on her age and history, this was the most likely possibility. She wasn’t acting sick, and there was no indication of acute illness. CKD is classified in stages I to IV based on laboratory findings. There are many possible underlying causes. Occasionally finding the etiology is relatively straightforward, such as in the case of a bacterial infection called pyelonephritis, which can be diagnosed with a simple urine culture. But more often than not, it’s not that easy. Definitive diagnosis can be expensive, and sometimes invasive, as with kidney biopsies. Owners may be understandably reluctant to put elderly animals through such procedures. Even with extensive diagnostics, we are often unable to determine a specific etiology other than “age-related” or “idiopathic” kidney failure. In these cases, treatment focuses on preventing and treating complications resulting from the decreased kidney function, trying to slow the progression, and providing supportive care.
Lili’s urine had a normal specific gravity, which was surprising. This indicated her kidneys were functioning appropriately to concentrate the urine. Most dogs with CKD are unable to maintain this ability, and their urine will be excessively dilute. There was no evidence of inflammation or infection such as red or white blood cells. The one abnormal finding was that she had glucose, i.e., sugar, in her urine. Technically called glucosuria, this is most commonly seen in diabetic animals, but we had checked Lili’s blood sugar previously and it had been normal, ruling out diabetes. What else could result in sugar in her urine? Well, the first thing (and I’ve seen it happen) is if the owner collected the specimen in a container that was contaminated with something sweet … like an old jelly jar. We had the owner bring a second sample in a different, immaculately clean container. Lili still had glucosuria. If it wasn’t jelly; then might it be Fanconi syndrome?
Fanconi syndrome is a complex disease in which the tubules in the kidneys malfunction and start “leaking” molecules that normally would not pass into the urine. Things like amino acid, proteins, potassium, sodium, calcium, magnesium, and bicarbonate. Classic Fanconi syndrome is a genetic disease that occurs primarily in basenjis. Somewhere between 10 and 30 percent of all basenjis are affected. But Lili isn’t a basenji. Depending on what source you read, Fanconi syndrome has also been reported in Norwegian elkhounds, schnauzers, border terriers, and Shetland sheepdogs, as well as reports of single cases in one Yorkshire terrier, one Labrador retriever, one cocker spaniel, one dachshund, one whippet, and one mixed-breed dog. In other words, unless you’re a basenji, it’s rare.
But there is another form called “acquired” Fanconi syndrome, more precisely dubbed “Fanconi-like syndrome” (FLS). FLS can be caused by cancer, toxins, drugs, and other kidney diseases. Clinical signs can vary, but may include increased drinking and urination, weight loss, poor hair coat, dehydration, and muscle weakness. In retrospect, Lili’s owner concurred that she was drinking and urinating excessively. Definitive diagnosis is made by putting together various pieces of a complex puzzle of laboratory abnormalities that involve testing both blood and urine, and often requiring sending specimens to a special lab at the School of Veterinary Medicine at the University of Pennsylvania that screens for amino acids in the urine.
As I pondered the possibility of FLS, I asked an odd question: “Has Lili had any chicken jerky treats from China?” Over the past decade, the Food and Drug Administration (FDA) has been investigating reports of illnesses associated with eating chicken or duck jerky treats from China. As of 2010, reports included more than 5,000 dogs, 25 cats, three people, and more than a thousand canine deaths. Symptoms reported ranged from gastrointestinal illness to kidney disease to convulsions, but the most surprising thing was the unusually high number of Fanconi-like syndrome cases.
Lili had eaten beef chew treats from China and some “chicken-flavored” ones, but none that contained actual chicken. If her owners opt to pursue this, first we will send urine and blood samples to UPenn to confirm or rule out FLS. If it’s not FLS, it might be another rare condition called primary renal glucosuria. If, however, FLS is confirmed, we could send the suspect chews to the FDA for testing. In either case, treatment consists primarily of supportive care. Many dogs with FLS got better when the owners stopped feeding the chicken jerky, and the dogs received supplemental veterinary care.
Lili is currently feeling fine. We stopped the NSAIDs, due to her compromised kidney function. “Don’t feed her any more of those treats,” I advised, just in case they were implicated. If you are ever suspicious that a treat or pet product has made your animal ill, save the original packaging and contact your veterinarian right away. For now, I have those chews safely stowed in my desk, while I wait to hear back from Lili’s family and the FDA.