IBD’s Cause: ‘The Million-Dollar Question’

Indy, a 2-year-old German Shepherd Dog, was having another bout of diarrhea. She’s had it since she contracted Clostridium perfringens, an intestinal bacterial
infection, as a puppy. In fact, said owner Karen Holowinski of Denver, Cob., “She gets these bad episodes of diarrhea every other month.”

Indy might not simply have a Clostridial infection, however. Its recurrence could be a sign of a more serious condition called inflammatory bowel disease,
which is not to be confused with the human condition, irritable bowel syndrome. IBD is a disease in which the digestive tract has an immune reaction
to normal bacteria in it and becomes inflamed. The afflicted dog may suffer chronic diarrhea, vomiting and weight loss. The disorder may be treated
but not cured.

“Inflammatory bowel disease is thought to represent an overreaction to the presence of normal bacteria in the intestine,” said Michael Stone, DVM, clinical
assistant professor at the Cummings School of Veterinary Medicine at Tufts University. “Recurrent, waxing and waning clinical signs are considered
IBD’s hallmark.”

Serious Consequences

The mean age for dogs developing IBD is 6 years, but those younger than 2 years of age have been diagnosed. If untreated, IBD can have serious consequences.
In Soft Coated Wheaten Terriers, for example, it’s a precursor for protein-losing enteropathy and protein-losing nephropathy, diseases that cause significant
protein losses in dogs. Other breeds prone to proteinlosing enteropathy include Basenjis, Shar-Peis, Norwegian Lundehunds and Yorkshire Terriers.

The cause of IBD? “That’s the million-dollar question,” said Cohn Burrows, DVM, BVetmed, Ph.D., MRCVS, at the University of Florida College of Veterinary
Medicine in Gainesville.

In an IBD-susceptible patient, the immune response of the intestine goes into overdrive. Dr. Burrows, a specialist in internal medicine and chair of Small
Animal Veterinary Medicine, offers his students a comparison, telling them it’s as though five years ago a dog who was a patient bit him in the arm.
“Then three years ago, I got stuck with a nail on the same arm. If you look at the scar tissue under the microscope, you’ll see the scar, but you won’t
he able to tell what caused it – the dog bite or the nail. It looks the same. That’s how IBD is.

 

“About 30 percent of dogs have either diarrhea or vomiting alone,” Dr. Burrows said. “It may involve the stomach, small intestine or colon. There may be
inflammation in one or all three.”

Some types of intestinal disease, such as lymphocytic-plasmacytic enterocolitis, have a genetic predisposition. Soft Coated Wheaten Terriers, Basenjis,
Lundehunds, German Shepherd Dogs and, in the United Kingdom, Golden Retrievers may be predisposed.

Veterinarians identify the type of IBD through an intestinal biopsy, ‘which may he performed through surgery or an endoscopic examination. One classification
for inflammatory bowel disease uses the predominant cell type involved. Among them:

  • Eosinophilic gastroenteritis an infiltration of white blood cells in the stomach or intestine. It’s seen predominantly in Rottweilers.
  • Histiocytic ulcerative colitis – a severe form of IBD seen only in Boxers. The inflammatory cells, or histiocytes, infiltrate the intestinal wall.
    Recent studies have demonstrated that this form responds to antibiotics.
  • Eosinophilic enterocolitis thought to be associated with food allergies or parasite infection.
  • Granulomatous enteritis – a very uncommon form of disease in dogs, similar to Crohn’s disease in humans.
  • Neutrophilic and lymphoplasmacytic enterocolitis – the most common forms of disease and unfortunately, of undetermined cause.

“Treatment for IBD involves accurately excluding all possible causes for inflammation of the intestine and toning down the immune system,” said Dr. Stone,
a specialist in internal medicine. “To exclude known causes of intestinal inflammation, many veterinarians consider these the minimum steps: blood
work, fecal analysis, de-worming and dietary trials with novel – never before ingested – ingredients. To tone down the immune system, prednisone and
other drugs may be used.”

Veterinarians may prescribe immunosuppressants and antibiotics to reduce bacteria in the intestines.


Food Intolerance

Most veterinarians opt for a bland diet that won’t aggravate IBD. “The best diet for IBD isn’t known,” said Dr. Stone. “If a patient responds to a change
of diet, then he doesn’t have IBD. He has more accurately food intolerance. I tend to use a bland diet initially for patients with true IBD along with
drug therapy. If food intolerance hasn’t been excluded, I’ll frequently start with a novel ingredient diet before reaching for drugs. The best novel
ingredient diet depends upon which diets have been previously fed to that patient, so an accurate dietary history is essential.”

Novel ingredients include fish, venison and kangaroo for a protein source and potatoes, barley or other grains for carbohydrates. Dr. Burrows recommends
going with a single novel protein source or switching to a prescription allergy diet available from many pet food manufacturers through veterinarians.

Because the cause of IBD hasn’t been determined, it’s impossible to suggest ways to prevent it. In some cases, IBD may simply be genetic. Preventing your
dog from scavenging is helpful but not always practical. You can store trash behind a cupboard or closet at home, but if your dog is a vacuum cleaner
while walking outdoors, he may pick up food wrappers – or worse – and swallow them before you can stop him.

Although IBD can’t be cured, the encouraging news is that, with proper diagnosis and treatment, this chronic illness can be successfully managed in most
cases.

Holowinski took her dog, Indy, to the veterinarian who put her on two antibiotics and a novel protein diet. After eight weeks, the veterinarian will evaluate
her to decide if more testing is needed.

 

 

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