Science

Companian Animal Disease Summary

SMALL INTESTINE OVERGROWTH

When abnormally large numbers of bacteria colonise the lumen of the small intestine.  Bacteria involved include Lactobacilli and Enterobacter.

Causes:

• Gastrointestinal obstruction - Retention of intestinal contents
• Malabsorption – retained nutrients encourage bacterial growth
• Impaired production of acid by the stomach
• Deficiency of enzymes leading to a reduced digestion of nutrient, bacterial overgrowth
• Impaired local immunity – loss of normal inhibition to bacterial growth

Symptoms:

• Chronic diarrhoea
• Weight loss
• Steatorrhoea - presence of excessive fat in the faeces

Diagnosis:

In addition, the results of the following tests are useful indicators of the presence of bacterial overgrowth:

• Breath hydrogen test - increased hydrogen 1-2 hours after a meal.
• Serum cobalamin - decreased in bacterial overgrowth.
• Serum folate - increased in bacterial overgrowth.
• Trypsin-like immunoreactivity (TLI test) - normal in bacterial overgrowth. 

Treatment:

• Correctly identifying underlying primary cause if there is one
• Tetracyclines at a dose rate of 20mg/kg body weight every 8 hours for 10-14 day course - which has to be repeated if the condition recurs

Breed Occurrence:

German Shepherd, may be due to low IgA concentrations in the small intestine.  IgA is an important immunoglobulin which forms part of the local defence mechanism against infectious agents.

Colitis literally means inflammation ( "..itis") of the colon ( "col...) - The large intestine/bowel.

Causes:

• Parasites
• Infectious agents e.g. bacteria
• Toxins
• Allergic reactions
• Psychogenic - stress
• Secondary to tumours

Symptoms:

• Diarrhoea
• Vomiting - sometimes
• Increased frequency of defaecation
• Straining when passing a motion - or passing mucus
• Passing clear mucus with or without faeces. Mucus can form a clear film over the faeces.
• Passing fresh bright-red coloured blood 

Diagnosis:

• A complete medical history and thorough physical examination
• Faecal examination to evaluate for the presence of disease causing bacteria or parasites
• Urinalysis to evaluate kidney function
• Abdominal X-rays to look for tumours or enlargement of abdominal organs
• Colonoscopic examination

Treatment:

Treatment depends upon the underlying cause - which may only be diagnosed by taking tissue biopsies. Treatments include:

• Dietary management
• Anti-inflammatory drugs
• Anti-parasitic drugs
• Surgery for tumours

 

EXOCRINE PANCREATIC INSUFFICIENCY (EPI)

EPI occurs when the pancreas stops producing and secreting enough digestive enzymes to digest food in the small intestine.

Causes:

• Pancreatic disease                                                                                                   
• Recurrent inflammation of the pancreas                                                             
• Obstruction of the pancreatic duct                                                                             
  
• Inadequate concentrations of all the pancreatic enzymes in the intestine              
• Pancreatic cancer
• Congenital abnormality (an abnormality present since birth)

Symptoms:

EPI can be subclinical for many months or even years, however symptoms can include:

• Weight Loss      
• Diarrhoea                                                                                                           
• Steatorrhoea                                                                                                                          
• If the condition has been present for a long time then poor hair condition and sometimes pallor due to anaemia
• Excessive food intake
• Flatulence (gas)
• Coprophagia (eating feces)
•  Pica (eating unusual things such as dirt)
• Borborygmus (a rumbling noise caused by gas passing through the intestines)

Diagnosis:

This needs to be confirmed by laboratory tests.

• In dogs the TLI test is often used, Trypsin-Like Immunoreactivity Test                    
• Faecal analysis for fat – detects Steatorrhoea                                                             
• Xylose absorption test – to test for bacterial overgrowth

Treatment:

• Replacement of pancreatic enzymes given orally
• Oral antibiotics to treat bacterial overgrowth

H₂ - receptor inhibitors (e.g. cimetidine) are useful because they reduce gastric acid secretion, and so less pancreatic enzyme is denatured during passage through the stomach.

The following dietary management is recommended:

• Feed a highly digestible, palatable, complete ration. Avoid home made rations.
• The ideal profile is a diet that is: low in fat content, contains medium-chained fatty acids, avoid excess carbohydrate, low fibre.
• Feed multiple small meals (at least 3 times daily)

Breed Occurrence:

Exocrine pancreatic insufficiency (EPI) occurs most frequently in dogs, and rarely in cats. The German Shepherd Dog is the breed most likely to be presented with EPI.  In Finland the Rough-coated Collie is also predisposed to develop the condition.

MALABSORPTION SYNDROME

Any disorder that interferes with the absorption of nutrients from the gut lumen contributes to a failure of normal absorption - and this is called malabsorption.

Causes:

• Small Intestine disease
• Inflammatory Bowel disease
• Chronic mucosal disease
• Enzyme deficiency
• Causes of villus atrophy -  histiocytic, eosinophilic, neutrophilic enteritis or lymphosarcoma

Symptoms:

• Weight loss
• Diarrhoea
• Steatorrhoea
• Increased appetitive
• Colitis

Treatment:

Specific treatment depends on the underlying cause.  However dietary management can help.

In malabsorption brush border enzymes disaccharidase concentrations are often significantly reduced (e.g. the enzymes maltase and lactase) so excess carbohydrate intake should be avoided. As these animals may have milk intolerance- milk and other lactose-containing products, such as yoghurt, should not be given.

Long term problems:

Long term problems depend upon the underlying cause (follow links above under causes). The result of chronic malabsorption is poor nutrition, and undernourished animals are more susceptible to infections and are less well able to recover from disease.

Breed Occurrence:

German Shepherd Dogs are predisposed to develop eosinophilic enteritis and small intestine bacterial overgrowth - both of which cause malabsorption.

Irish Setters have been recorded to develop Gluten-sensitive enteropathy which results in malabsorption. 

INFLAMMATORY BOWEL DISEASE (IBD)

This disorder is due to an invasion of the wall of the large bowel by certain types of body cells.  Eosinophilic Colitis is a good example. Another common cellular infiltration into the wall of the large bowel is due to lymphocytes and plasmacytes.

Causes:

Unknown, however there are several theories:

• Immune disorders
• Drugs
• Diet
• Infectious agents
• Parasites

Symptoms:

• Vomiting
• Diarrhoea
• Inappetance
• Weight loss
• Excessive gas production
• Increased gut noises
• Abdominal pain
• Blood or mucus in stools
• Increased frequency of defaecation

Treatment:

• Dietary therapy -  identify specific foods which may be irritating the animal
• Drugs – immune suppressant drugs may control the symptoms but not eradicate them permanently.

Breed Occurrence:

• Boxers
• German Shepherd
• French Bulldog

Colic is the name given to a symptom – abdominal pain.  There are a number of different types of colic:

• Gas – collection of gas in the bowel
• Obstructive – mass of food accumulates in the bowel and prohibits passage through the intestines
• Sand - accumulation of sand in the gut
• Twisted gut – a portion of the intestine becomes twisted

 Causes:

• Parasites
• Sudden changes in diet
• Insufficient water or unclean water
• Irregular feeding

Symptoms:

• Lying down more than usual
• Getting up and lying down repeatedly
• Standing stretched out
• Standing frequently as if to urinate
• Turning the head towards the flank
• Repeatedly curling the upper lip
• Pawing the ground
• Kicking at the abdomen
• Rolling

Treatment:

The points below are more prevention than treatment, the best treatment is to take the horse immediately to a veterinary surgeon who will assess the condition and the corrective actions required.  If the horse is suffering from colic then try to avoid putting it near feed and remove objects that may harm it whilst it is rolling whilst waiting for a vet.

• Establish a regular routine of feeding, turnout and exercise
• Make sure the feed is of good quality and plenty of good hay
• Ensure the horse always has access to fresh water
• Establish a regular routine of deworming
• provide access to forage for as much of the day as possible
• do not over graze pastures

There are 3 stages:

• Developmental – often completely undetectable
• Acute – occurs anywhere from 24 – 72 hours after the initial damage to the basement membrane
• Chronic – after 48 hours of lameness or after rotation and/or sinking of the coffin bone

Causes:

No exact cause known, however many theories:

• Carbohydrate overload: excess grain, lush pasture, sudden feed change
• Edotoxemia, sepsis, shock: colitis, intestinal obstruction, pleuritis, retained placenta, metritis, abortion
• Excessive unilateral weight bearing: post-fracture repair, severe lameness
• Management: black walnut bedding, cold water ingestion by overheated horse, overweight animal, unconditioned animals worked on a hard surface
• Miscellaneous: corticosteroid treatment, Cushing disease, hypothyroidism

• Severe lameness, reluctance to move, or even recumbency
• Typical stance to try to get weight off the toes: front feet out in front if only the forelimbs are involved; all four legs in under the body if all limbs are involved; pointing with a leg if only one limb is involved
• Pain to pressure or percussion over the toe area
• Systemic changes; anorexia, anxiety, increased respiration and pulse rates are often seen

Chronic:

• Rings in hoof wall that become wider as they are followed from toe to heel
• Bruised soles or "stone bruises"
• Widened white line, commonly called "seedy toe," with occurrence of seromas (blood pockets) and/or abscesses
• Dropped soles or flat feet
• Thick, "cresty" neck
• Dished hooves, which are the result of unequal rates of hoof growth (The heels grow at a faster rate than the rest of the hoof, resulting in an "Aladdin-slipper" appearance.)

Treatment:

• Diagnosing and treating the primary problem (Laminitis is often due to a systemic or general problem elsewhere in the horse's body.)
• Dietary restrictions
• Treating with mineral oil, via a nasogastric tube, to purge the horse's digestive tract, especially if the horse has overeaten
• Administering fluids if the horse is ill or dehydrated
• Administering other drugs, such as antibiotics to fight infection; anti-endotoxins to reduce bacterial toxicity; anticoagulants and vasodilators to reduce blood pressure while improving blood flow to the feet (Corticosteroids are contraindicated in laminitis, as they can actually cause laminitis or exacerbate existing cases.)
• Stabling the horse on soft ground, such as in sand or shavings (not black walnut), and encouraging the horse to lie down to reduce pressure on the weakened laminae
• Opening and draining any abscesses which may develop

GASTRIC ULCERS

Excess acid in the stomach can eat through the protective lining and damage the stomach, causing ulcers.

Causes:

• Feeding management practices
• Physical stress
• Diet

Any horse with serious illness is also at risk from developing ulcers.

Symptoms:

Ulcers can go unnoticed for sometime due to the fact that there are no obvious physical signs.  However there are a few factors that could indicate the presence of gastric ulcers:

Adult horses:

• Poor performance
• Colic
• Poor appetite
• Attitude changes
• Poor body condition

Foals:

• Intermittent diarrhoea
• Intermittent colic
• Rough hair coat
• Poor growth

Treatment:

• Plenty of access to fresh hay, water and feed
• Where possible provide as much pasture turnout as possible
• Inhibiting gastric acid secretion or neutralizing the acid produced
• Antacids to neutralise stomach acid

DIETARY FIBRE

This is a term used to describe a group of compounds which are found in foodstuffs.  There are two types of fibres:

• Soluble, e.g. pectin, guar gum
• Insoluble, e.g. cellulose

These are readily available as supplements, as constituents in raw ingredients and incorporated in "special diets" developed to be used in the management of animals with known disease profiles.

These groups of compounds are mainly complex carbohydrates. Generally, they are also not digested by enzymes secreted by other single-stomached animals such as the cat and dog. However, it is inaccurate to regard dietary fibres as being inert because they have various effects on the body, and although not digested in the small intestine, they are metabolised by bacteria in the large intestine. The resulting substances of this process (mainly short-chained fatty acids such as acetic, propionic and butyric acids) acidify the colonic contents resulting in water retention and faecal bulking.

In ruminants (cattle, sheep, goats) dietary fibre is fermented by ciliates, protozoa, yeasts and fungi activity as well as bacteria in the rumen making them available for absorption in the small intestine.

Rations high in dietary fibre produce the following effects:

On the intestine

• Increased small intestine wall thickness (mucosa)
• Increased small intestine weight
• Changes in the villi:
• Increased number of neutrophils
• Increase mitosis (cell division rate)
• Increased number of crypt cells
• Blunting and disarray of villi (soluble fibre)

• Thinning of colon wall
  

On intestinal contents

• Alter the transit time of food through the intestinal tract. Increased secretion of enzymes
• Altered pH of intestinal contents (chyme)
• Increased viscosity of chyme
• Reduced digestion of nutrients
• Reduced absorption  of nutrients
• Slows the absorption rate of nutrients e.g. glucose
• Increased colonic fermentation

On faecal production

• More faecal waste material
• Faecal bulking due to retention of water
• The faecal stool is softer and easier to pass
• More gas production (due to increased fermentation)
• Increased number of neutrophils