Diarrhoea in the dog

The terms that I will use in this article are defined below:

Defecation - The discharge of Faeces from the body
Dyschezia - Pain or difficulty on defecation
Haematoc - Presence of fresh blood in formed faeces
Melaena - Dark. tarry faeces containing blood
Steatorrhoea - Greasy, pale, bulky, evil smelling faeces
Tenesmus - Abdominal straining which may be associated with either urination or defecation
Diarrhoea - This can describe an increase in the percentage of fluid present in faeces, an increase in the quantity produced or an increase in the frequency with which an animal defecates. All three changes need not be present at the same time.
Dysentery - Watery diarrhoea containing fresh blood.

The normal motion of a dog varies tremendously depending upon diet, temperament, training, exercise and location, but it is considered normal for a dog to defecate between one and four times daily. The daily stool weight for a Dachshund is 70g, for a staffie 220g and for a Newfoundland about 500g. A Staffie will pass around 3 litres of fluid into its small intestine each day. The fluid is from ingested liquid and from - salivary, gastric, intestinal, pancreatic, and hepatic secretions. As 90% of this fluid is absorbed, it is obvious that anything interfering with this secretion or, equally important, with its absorbtion, will have a profound effect upon the volume excreted in the faeces and therefore, the
consistency of the faeces. Dogs will pass faeces even when they are not eating because a significant percentage of faeces are composed of dead cells from the bowel lining and from dead bacteria normally found on the bowel.

Thefour reasons why a dog develops diarrhoea are:-

1. Osmotic diarrhoea - If there is a build up of food particles in the bowel due to failure to digest or absorb food, then water is attracted via osmosis into the large bowel causing diarrhoea.
2. Secretary diarrhoea - If the lining of the bowel in inflamed then there is an outpouring of fluid into the lumen of the bowel. Some bacteria produce chemicals which also cause the secretion of fluid into the bowel .
3. Increased permeability - If the lining of the bowel becomes damaged proteins leak into the lumen of the bowel, thus attracting Osmosis.
4. Motility disorders - If food is passed too slowly through the bowel water and food particles are not absorbed resulting in osmotic diarrhoea. Diarrhoea is divided into acute and chronic. Acute diarrhoea is of sudden onset and rarely persists for longer than a few days. Most of the cases in this group would clear up without treatment. Conversely, this category also includes acute diarrhoea which can be life threatening, eg canine parvovirus. Chronic diarrhoea include the long term diarrhoea which have persisted for several weeks and recurrent cases with a history of diarrhoea interspersed with bouts of normality.

A. ACUTE DIARRHOEA
There are six main causes of acute diarrhoea:

1. DIET: This is by far the commonest cause of diarrhoea in the dog. A common cause of diarrhoea especially, in puppies, is when the dog consumes more than it can efficiently digest before it's next meal. This results in osmotic diarrhoea. The treatment is feeding small meals frequently and avoiding the last meal at night as most dogs defecate within a few hours of consuming a meal. Changing a dogs diet, especially from a complete, cereal-based diet to a canned meat diet, can cause diarrhoea for a few days. In most cases the diarrhoea will stop if the dog is continued to be fed the canned meat diet. A dogs diet should not be changed too often in case diarrhoea develops and when it is changed, it is worthwhile "weaning" gradually from one diet to another. Milk should not be given to a dog with diarrhoea because levels of the enzyme responsible for its breakdown in the bowel, Lactase, decrease with age. Raw egg white can cause diarrhoea as it contains an enzyme that impairs normal digestion. Fortunately, cooking the egg white kills the enzyme. Soya bean containsthesame enzyme.
Fresh meat diets are far more likely to cause diarrhoea than commercial diets. Offal, especially liver, kidney and heart are the most common fresh meats that cause diarrhoea. Certain diarrhoeic causing
bacteria increase in numbers when a dog is fed a rich meat diet. Feeding live yogurt because it contains lactobacilli controls their numbers This is a different bacterium, which produces a more stable environment in the bowel. Dogs on fresh meat diets that develop diarrhoea should also be fed on heaped tablespoon of fine bran per 450g of meat per day. Fibre or roughage is very important for normal bowel function and meat contains a very little fibre. In summary if you feed your dog a fresh meat diet, liver, yogurt, bran and a vitamin-mineral supplement should be added

2. BACTERIAL DIARRHOEA Bacteria can cause a severe, life threatening diarrhoea in pups, especially E Coli, Salmonella spp,
Campylobacter spp, Staphylococcus spp and Streptococcus spp.
3. VIRAL DIARRHOEA. Canine Parvovirus is the most important of life threatening diarrhoea in the dog. Rotavirus and coronavirus usually
cause a transient diarrhoea that doesn't make the dog ill.
4. HAEMORRHAGIC GASTRO-ENTERITIS. HGE. HGE is a
acute condition which presents as sudden onset vomiting and diarrhoea
rapidly progressing to dysentery which appears to be frank blood. It is
thought to be the cause of toxins produced by bacteria. The clinical picture
is very similar to canine parvovirus infection. These dogs are very ill and
require emergency treatment.
5. STRESS. Stress can cause acute diarrhoea in the dog. These dogs
tend to pass normal motions in the morning but the consistency becomes
more fluid as the day progresses.
6. PARTIAL OBSTRUCTION OF THE LOWER BOWEL.
Intussusception, is where the bowel folds in on it's self causing sudden
onset, blood stained, diarrhoea. This condition requires surgery.

TREATMENT OF ACUTE DIARRHOEA.
I . DIET. Starve the dog for 24 hours and then feed a bland diet until
diarrhoea resolves. Boiled chicken, fish and rice is very good. Prescription
diets are excellent. Examples are Hill d/d and i/d and pedigree select
protein.
2 . FLUIDS. Oral rehydration solutions significantly speed up
recovery from acute diarrhoea. Lectade is an example. Where the
diarrhoea has led to dehydration the dog will require a drip.
3 . MOTILITY MODIFIERS. An example is Lomotil and
Immodium. lpersonallyhaveneverprescribedthesedrugs.
4. ANTIBIOTICS. Oral antibiotics should not be used routinely in
the treatment of acute diarrhoea because bacteria may develop resistance,
colitis may develop, the dog may develop into a carrier state, antibiotics
may predispose to systemic infection from the gut and because they effect
the normal homeostatic balance in the bowel flora. Antibiotics are used
when the dog is ill, has blood in it's faeces or when a bacteria has been
cultured from its faeces.
5. ABSOR-BANTS. Kaolin, bismuth and charcoal are thought to be
of benefit in the treatment of acute diarrhoea.
6. STEGATOX. This is a new drug that builds up toxins in the
blood. It is excellent in canine parvovirus and HGE infections.