Inflammatory Bowel Disease (IBD) in Cats

What is inflammatory bowel disease?

Inflammatory bowel disease is a group of disorders caused by the infiltration of inflammatory cells (white blood cells) in the mucosa of the gastrointestinal tract. It can affect both the upper and lower intestinal tract.

• Colitis: Inflammation of the large intestine.
• Enteritis: Inflammation of the small intestine.
• Enterocolitis: Inflammation of the large and small intestine.
• Gastritis: Inflammation of the large and small intestine as well as the stomach.

IBD’s are classified according to the type of inflammatory cell infiltrating the gastrointestinal wall.

• Lymphocytic-plasmacytic enterocolitis: The most common form of IBD. Lymphocytes (a type of white blood cell) and plasma cells (antibody-producing cells) are the predominant types of inflammatory cells present in the mucosa of the small and large intestine.
• Eosinophilic Enterocolitis: The second most common form of IBD, eosinophils are present in the stomach, small intestine or colon,
• Granulomatous (Regional) enteritis: Macrophages in the lower small intestine and colon.

IBD is the leading cause of chronic vomiting and diarrhea in cats. It can affect cats of any age, although it occurs more often in middle-aged to older cats. Persistent inflammation results in fibrosis (formation of scar-like fibrous tissue), poor digestion and absorption may also result.

Causes

The cause of IBD is still unknown although evidence suggests that it could be the result of certain bacteria, dietary allergy or intolerance, genetic influence and parasites causing cats to produce antibodies that attack the digestive tract.

There is increased attention towards the role of gut microflora (gut microbiome). These are a group of micro-organisms that live in the gut and has many roles such as inhibiting pathogens, metabolic function, assisting the immune system, regulating the production of antibodies.

Several diseases which include digestive disorders are now being linked to gut microbiome due to an inappropriate immune response, an overgrowth of certain bacteria or reduced diversity of gut microbiome. While still in its infancy, this area of medicine is one that many researchers believe shows great promise for several medical conditions.

Symptoms

Clinical signs vary depending on the region affected and may include:

• Diarrhea (possibly outside the litter tray)
• Smelly feces
• Blood or mucus in the stool
• Lethargy
• Loss of appetite or increase in appetite
• Borborygmus (rumbling sound due to gas in the intestines)
• Vomiting
• Weight loss

Diagnosis

The veterinarian will perform a physical examination of your cat upon which may show weight loss, dehydration, thickened intestinal loops upon palpitation. He will also obtain a medical history from you.

Many other conditions may produce similar symptoms to IBD so your veterinarian will wish to rule these out. Other conditions include parasites, neoplasia, hyperthyroidism, diabetes, salmonellosis, campylobacteriosis, chronic renal failure, liver disease, chronic pancreatitis.

Diagnostic workup:

• Baseline tests: Biochemical profile, complete blood count, and urinalysis to evaluate the overall health of the cat and check kidney and liver function as well as blood sugar levels, which can indicate diabetes.
• T3 and T4 tests: These blood tests measure levels of T3 & T4 hormones, which are secreted by the thyroid gland, elevated levels occur in cats with hyperthyroidism.
• Fecal examination/fecal flotation: To look for the presence of parasitic worm eggs or giardia cysts.
• FIV and FeLV tests: To determine a secondary disease is present.
• X-rays/ultrasound: These imaging techniques don’t help diagnose IBD but are useful to rule out other medical conditions such as cancer. Ultrasound may see evidence of a thickening of the intestinal wall.
• Biopsy/histopathology: The only definitive way to diagnose IBD. Increased numbers of plasma cells, lymphocytes, eosinophils, and neutrophils are present in the intestinal wall. The types of cells present will provide a diagnosis of which type of IBD the cat has.

As pancreatitis can run concurrently with IBD, your veterinarian may also wish to run one (or more) of the following tests;

• fTLI (feline Trypsin-Like Immunoreactivity): A measure of the concentrations of trypsin-like proteins in serum.
• fPLI (feline Pancreatic Lipase Immunoreactivity): A test to measure feline pancreatic-specific lipase (an enzyme secreted by the pancreas which breaks down fat) immunoreactivity in serum. Normal levels are 2.0-6.8ug/dL, in cats with mild or resolving pancreatitis, levels may be 6.8-12ug/dL and cats with pancreatitis, over 12ug/dL.
  

Treatment

The goal of treatment is to identify and treat the cause, where possible as well as manage symptoms. Treatment requires a multimodal approach, which may include the following:

Dietary management:

• A highly digestible, low-fat diet containing a novel protein.
• Metamucil (psyllium) to add bulk to the feces.
• Probiotics to promote healthy gut bacteria.
• A high fibre diet in cats with colitis.

Medical management:

• Corticosteroids: Prednisone is the drug of choice (as well as dietary therapy) for all types of
  inflammatory bowel disease. These drugs have anti-inflammatory and immunosuppressive properties.
• Antibiotics: Metronidazole is an antibiotic with anti-inflammatory properties and can be used along with diet therapy to help manage IBD.
• Other immunosuppressive drugs: Azathioprine (brand name Imuran) is an immunosuppressive drug that can be used in combination with corticosteroids. There can be side effects; it is therefore only used as third-line therapy in refractive (unresponsive to diet and corticosteroids alone) IBD. Cats on this drug should have a CBC every week for the first month and every 2-3 weeks while the cat is on the drug.
• Sulfasalazine: This anti-inflammatory medication is the drug of choice for lymphatic-plasmacytic colitis.

Fecal microbiota transplant (FMT):

Fecal transplants are still very new and not readily available yet, but interest in this therapy is growing. It shows great promise for helping cats with digestive issues such as inflammatory bowel disease. A healthy donor with a healthy and diverse microbiome provides a stool sample. This is introduced to the host cat in several ways such as colonoscopy, endoscopy, enema or pill to restore a diverse microbiome.

References:

[1] The Cornell Book of Cats