January 22, 2014
A study of 100 cats with a history of chronic vomiting, weight loss, chronic diarrhea or a combination was recently accepted for publication by the Journal of the American Veterinary Medical Association.1 The authors, whom I led, concluded that chronic small bowel disease likely is the cause of these clinical signs in hundreds of thousands of cats.
Chronic vomiting, present in 73 percent of the cases, is so common that many veterinarians and cat owners have made excuses for it.
The top four reported to me over the years are:
* He eats too fast;
* She has a sensitive stomach;
* It’s just hairballs; and
* “He’s just a puker,” to quote one of my clients.
Consequently, the typical approach has been the use of diets for “sensitive stomachs,” diets for hairballs, hypoallergenic diets, medications for hairballs and antiemetics (metoclopramide, ondansetron, maropitant, famotidine, etc.).
Often there is improvement in clinical signs, but rarely are they completely relieved. In addition, the improvement often diminishes over time.
My two clinical associates and two pathologists teamed with me to better understand the cause of chronic small bowel disease in cats.
One hundred cats with the aforementioned clinical signs were examined by abdominal ultrasound. The small bowel wall thickness was measured in several places; if one or more measurements were 0.28 cm or greater, surgery was performed. At surgery, at least three full-thickness biopsies were collected from the small bowel using a 6 mm biopsy punch so all layers of the bowel wall could be examined.
In addition, the liver (wedge) and pancreas (4 mm biopsy punch) were biopsied. Histopathology and immunohistochemical staining were performed on all samples, and PCR for Antigen Receptor Rearrangement (PARR) was performed on samples deemed to be “ambiguous.” “Ambiguous” was defined as a cellular composition that had characteristics of both inflammatory disease and small cell lymphoma, the two most common diagnoses.
In the paper, we use the term “chronic enteritis” instead of “inflammatory bowel disease.”
IBD is one of several causes of chronic enteritis and requires more testing to rule out other known causes before the term IBD is justified. However, ultimately IBD, as a diagnosis of exclusion, is correct in a high percentage of cases.
The final diagnoses of the 100 cats are shown in Table 1. It is notable that the incidences of chronic enteritis and neoplasia are almost equal. It also is notable that the cats with lymphoma were slightly older than those with enteritis.
There is growing evidence that some cats with chronic enteritis transition into lymphoma. This should motivate the practitioner to be aggressive in getting biopsies of these cats so the disease can be diagnosed at the more treatable stage.
| Symposium set at WVC
Gary Norsworthy, DVM, Dipl. ABVP, and J. Scot Estep, DVM, Dipl. ACVP, will present a symposium on small bowel disease at the 2014 Western Veterinary Conference in Las Vegas in February. The emphasis will be on diagnosis, but therapy also will be included.
Pathologists will be especially interested in Dr. Estep’s findings and how they affect appropriate diagnostics.
The presence of vomiting alone and vomiting with weight loss are the basis for my theory that small bowel thickening causes hypomotility. Hair and food move through the bowel at subnormal speed. When more hair or food is ingested, the full bowel results in reflux vomiting. As the bowel wall thickens further, nutrients are not absorbed properly, resulting in weight loss and compensatory polyphagia, well recognized clinical signs of cats with intestinal lymphoma.
Another notable finding in this study is that vomiting of hairballs is really not as normal as we have thought. The vomitus of many of the cats contained hair or hairballs more than 50 percent of the time.
I hypothesize that formation and vomiting of hairballs are due primarily to hypomotility of the small bowel. Instead of moving aborally at the normal speed, hair moves slowly, resulting in hairball formation.
I am convinced that the vomiting of hairballs is a sign of chronic small bowel disease if it occurs twice a month or more in any cat; or if it occurs once every two months or more in shorthaired cats; or if it occurs in cats that are not fastidious groomers, i.e., presented with many mats in their hair coats or with heavy dandruff.
About 25 percent of the cats in the study were presented for an annual examination. I begin my annual examinations with the client completing a history form that asks about several clinical signs. Vomiting is the most commonly reported clinical sign and is often accepted by the client as insignificant based on one or more of the excuses listed above.
Thus, one of the best ways to find chronic small bowel disease, and many other diseases, is to perform an annual examination that includes proper history taking. This must include proactively asking about chronic vomiting; otherwise, clients will often not report it.
Some veterinarians use endoscopy to obtain gastric and small bowel biopsy samples. However, surgical biopsy has two distinct advantages. First, 76 percent of the cats in the study had segmental disease as evidenced by both normal and abnormal ultrasound findings and proved by visual evaluation of the tissues at the time of surgery. Many cats had disease that was limited to areas not accessible to the endoscopic biopsy forceps.
| TABLE 1
Final diagnoses of 100 cats with clinical signs of chronic small bowel disease.
• Lymphoma (46)
• Small cell (39)
• Lymphoblastic (7)
• Mast cell disease (3)
• Adenocarcinoma (1)
Second, endoscopic biopsies generally only contain mucosal tissue. Pathologists prefer to examine all of the layers, especially in ambiguous cases. The therapeutic significance of this will be shown in a subsequent paper in which we will show the difference in therapeutic response and prognosis in cats with villus and mucosal lymphoma vs. those with lymphoma that infiltrates deeper into the bowel wall.
The findings of this study should motivate the practitioner to be much more proactive in working up cats with signs of chronic vomiting, diarrhea and weight loss or a combination of these signs.
Chronic small bowel disease is very common and can cause all of these signs.
It is time to quit accepting our timeworn excuses and treating these cats symptomatically. Get a diagnosis so you can treat these cats appropriately and potentially prevent the transition from IBD to lymphoma.
Dr. Norsworthy, Dipl. ABVP, operates Alamo Feline Health Center in San Antonio. He is a member of the Veterinary Practice News editorial advisory board.
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