A visiting feline specialist has challenged what he labelled as “the greatest of all feline myths”: namely that chronic vomiting in the cat is normal.
Gary Norsworthy, based the Alamo Feline Health Centre in Texas, says that all too frequently chronic vomiting in cats is dismissed as result of eating too quickly, anxiety, hairballs or the fact that the cat is “just a puker”.
But Norsworthy presented compelling data at the Centre for Veterinary Education’s annual Feline Medicine conference which suggests that vomiting reflects significant small bowel disease in the cat.
“The typical history of these cats is that they are lifelong vomiters, often with a recent increase in the frequency of vomiting,” Norsworthy said. “It might have been occasional for months to years, then one to three times a month, and now its daily but the cat seems well and has a good appetite.”Some cats present with concurrent weight loss or diarrhoea, but for many, chronic vomiting is the only clue that something is amiss.
“The problem is that we have cat owners and veterinarians feeding off each other and accepting that this is normal.”
But according to the new data presented by Norsworthy, vets will only find the root of the problem if they seek it out.
“You won’t find the answers on your classic minimum database,” he says. Rather, Norsworthy recommends abdominal ultrasound with multiple intestinal wall measurements in all cats presented with a history of chronic vomiting – unless of course a metabolic cause is detected.
While the textbooks suggest that an intestinal wall thickness of 3mm is normal, Norsworthy considers a wall thickness of 2.8mm or greater a justification for exploratory surgery and full thickness biopsy.
“Most small bowel disease is segmental, which means that even cats with disease will have some normal bowel wall on ultrasound which is why it is important to measure a number of sites.”
“Ultrasound allows documentation of small bowel thickening which you can show the owner,” Norsworthy said. “By taking them to ultrasound with you, it is much easier to convince clients to consent to an exploratory laparotomy on these cats when they can see the problem.”
Ultrasound alone does not yield a definitive diagnosis.
“Loss of intestinal wall layering is strongly correlated with neoplasia, however most cats with lymphoma don’t have loss of layering so we cannot use ultrasound to distinguish inflammatory bowel disease from lymphoma.”
Differential diagnoses for non-obstructive small bowel disease in the cat include inflammatory bowel disease, neoplasia (most commonly small cell lymphoma, lymphoblastic lymphoma or mast cell tumours), or food intolerance or allergy.
Norsworthy analysed data from 94 cats presented to his practice with a history of vomiting, diarrhoea and/or weight loss, plus an abnormal ultrasound, which underwent exploratory laparotomy and full thickness intestinal biopsies.
Of these, 93 had abnormalities on histopathology, with a histopathological diagnosis of lymphoma in 53 per cent of cases and inflammatory bowel disease in 44 per cent of cases. Adenocarcinoma and mast cell tumours were found in 4 per cent of cases.
The oldest cat in the case series was 18, while 51 were aged over 15 years. Thirty-three per cent of the cats taken to surgery had presented for a routine annual health check, with owners frequently reporting that vomiting was simply due to hair balls.
But Norsworthy believes that hair balls are often a symptom of underlying small bowel disease.
“When you find a hairball obstruction, assume there is disease affecting small bowel motility. The sight of a hairball [on exploratory laparotomy] can skew the diagnosis – look downstream and biopsy the intestine distal to the obstruction.”
Norsworthy argued that hairballs in cats are abnormal if they occur in short-haired cats or those that are noted to be poor groomers, and if they occur at a rate of more than twice a month.
“If the cat is taken to ultrasound and the findings are normal then I feel okay about treating this cat empirically with hairball diets and lubricants, but if the response to symptomatic treatment decreases over time I would want to re-ultrasound the small bowel. The risk is that if chronic vomiting of hair balls is due to chronic small bowel disease, symptomatic treatment masks the disease allowing it to progress.”
Norsworthy’s study group had several cats with areas of inflammatory enteritis and other areas of lymphoma. This is consistent with the belief that inflammatory bowel disease can progress to lymphoma in cats the consequences of delayed diagnosis of small bowel disease can be catastrophic.
Norsworthy said the findings of his study, which he is preparing for publication, support the need for aggressive investigation of small bowel disease. This is evidenced by an increase in the number of exploratory laparotomies he undertakes – from 33 in the last six months of 2011 to 14 in January 2012 alone.
ANNE FAWCETT