By Arnold Plotnick, MS, DVM, ACVIM
Pica – When Cats Eat Weird Things
“Tom”, an 8-month old male domestic shorthaired kitten, presented to my hospital with a complaint of lethargy and unusual ingestive behavior. According to his owners Pat Galloway and Peter Webb, the normally rambunctious kitten had become lethargic over the past two days, spending most of his time sleeping. The cat’s appetite had markedly decreased, although he was still gaining weight nicely and was a healthy 8 ½ lbs. They also reported that Tom had been seen eating his clay cat litter and licking the floor around his litter box. Physical examination revealed pale gums, and a quick in-house test confirmed that Tom was severely anemic. Additional tests showed that Tom’s bone marrow was not properly compensating for the anemia by producing more red blood cells, suggesting a primary bone marrow disorder. Tom was given a life-saving blood transfusion, and a bone marrow evaluation was performed soon afterward. Tom was diagnosed with pure red cell aplasia (PRCA), a severe form of anemia that is believed to result from an immune system disorder. High doses of immunosuppressive drugs were prescribed, and Tom’s red blood cell count increased steadily over the course of a few weeks. Meanwhile, Pat and Peter had quickly switched from clay-based to wheat-based litter, in an attempt to discourage Tom from eating his litter, as clay litter contains bentonite which can form a hard clump in the intestines, leading to obstruction. The switch worked; Tom stopped nibbling on his litter. As the anemia came under control, an attempt was made to try to reduce Tom’s medication dose. Eventually, his condition was maintained on every other day therapy, and Tom appeared healthy. Three months later, however, Tom presented to my hospital with a complaint of a gradual onset of lethargy and decreased appetite over the past week. Pat and Peter also reported an unusual new behavior: Tom had begun licking the silverware. Physical exam and blood tests revealed that Tom’s condition had relapsed. Fortunately, he responded well to another transfusion and to an increase in his medication, and Tom is now back to normal; no more anemia, and no more licking of the silverware.
“Pica” (pronounced “PIE-kuh”) is the voluntary ingestion of non-edible materials. The term comes from the Latin word “magpie”, because magpies are said to eat almost anything. Pica accounts for approximately 2.5% of abnormal behaviors in the domestic cat. The etiology of true pica is not known, although mineral deficiencies or psychological disturbances are often blamed. Tom’s case is interesting in that his pica – eating litter and licking silverware – seemed to be clearly connected to a medical disorder (his anemia). Wool-sucking is a commonly described abnormal ingestive behavior in cats. Wool-sucking, however, is a compulsive, misdirected form of nursing behavior and technically should be distinguished from true cases of pica.
“Kittens nurse fairly actively for the first seven weeks of their lives, with mom rebuffing them at the latter end of the period in order to ‘teach’ them to fend for themselves”, explains Dr. Nick Dodman, Director of the Animal Behavior Clinic at the Cummings School of Veterinary Medicine at Tufts University, and author of book The Cat Who Cried for Help. “’Comfort nursing’ (running to mom for a couple of quick sucks even when the milk bar is dry) is normal kitten behavior, even up to 6 months of age. As the kitten grows older and shifts its preference to solid food, the drive to nurse fades.” If, however, this natural progression is disrupted by abrupt early weaning while the kitten’s nursing drive is still very powerful, the kitten may displaces its nursing onto substrates that look or feel like mom. “They may begin sucking on themselves, their littermates, or certain wooly materials, especially wool itself”, says Dr. Dodman. Human infants show similar behavior when they suck their thumbs or a pacifier. In general, the younger a kitten is when it is weaned, the stronger the nursing drive, and the more persistent this non-nutritional sucking may become. Wool sucking usually fades over time as the kitten develops other interests. For those kittens whose wool sucking has apparently faded into oblivion, however, vague memories of this behavior may persist throughout life, and in moments of stress or conflict, it may resurface as a comfort behavior. In some cases, it may assume compulsive proportions. In other cats, wool sucking doesn’t resurface, possibly because serious conflict does not arise. Wool sucking is usually not a problem, “especially if the behavior remains at the ‘wool sucking only’ stage”, says Dr. Dodman. Some cats, however, progress to actually eating the non-nutritional materials, predisposing the cat to potentially serious problems such as gastrointestinal obstructions. Such was the case with Pumpkin. Many years ago, while working for a feline-exclusive veterinary practice in Baltimore, I was presented with a big 4 year-old orange male tabby. The complaint was poor appetite and vomiting of three days duration, and before I could even start my exam, Pumpkin’s owner warned me that Pumpkin had always had a penchant for plastic bags. Three years prior, Pumpkin had a plastic bag surgically removed from his stomach, and his owner was having that unmistakable feeling of déjà vu. Sure enough, x-rays revealed the presence of something odd in Pumpkin’s gastrointestinal tract, and during exploratory surgery, a sizeable chunk of a plastic grocery bag was extracted from Pumpkin’s intestine. Fortunately, Pumpkin recovered uneventfully. An attraction to plastic is a common scenario encountered by feline practitioners. Exactly why cats like plastic remains unknown, although several theories abound. Some people have speculated that cats like the coolness of the plastic, or the texture on their tongue, or perhaps the sound it makes when they lick. The most logical reason I’ve heard, however, is that cats like licking or eating plastic bags because rendered animal fat (also called “tallow”) is utilized during the manufacture of some plastic bags, and that some cats can detect the smell and enjoy the taste. Other versions of this explanation have implicated petroleum products and gelatin as the enticing ingredients. Gelatin, in fact, is used in the manufacture of many items including the emulsion used in photographs, which may explain why my own carnivorous cat, Emma, enthusiastically licked clean all of my unattended family photos one afternoon. I’ve never been able to confirm the tallow-petroleum-gelatin theory, so visitors to this website should not take this as the gospel truth. But it sure makes sense to me. Because pica can be a sign of an underlying medical problem, like Tom’s anemia, cats displaying unusual ingestive behavior should be examined by a veterinarian. Certainly, cats with unexplained gastrointestinal symptoms and a history of eating unusual objects should be examined right away, and clients should inform the veterinarian if the cat has a known tendency toward dietary indiscretion, since GI obstructions may be life-threatening. Pica might seem like charming, quirky behavior, however, because of the potential harm from eating non-nutritional material, cat owners should discourage this behavior.