Diarrhoea is an increase in the frequency of defecation and or the lowering of faecal consistency.
Diarrhoea that lasts less than 7 days that has an abrupt onset is very common in cats and dogs.
Diarrhoea has many possible causes that disrupt the normal function of the intestinal wall in both
the small and large intestine. Diarrhoea develops usually as a result of four main processes affecting
digestion and absorption:
- Osmosis which is where foods that are not properly digested sit in the gut, ferment and
draw water into the bowel leading to watery stools. This is common with sudden changes in
diet, overconsumption of food and ingestion of spoiled foods.
- Secretory diarrhoea where the cells lining the gut are irritated and secrete large volumes of fluid into the bowel leading to watery bowel contents. An example of this would be infection with Salmonella bacteria.
- Increased permeability of the intestine is where water and other substances (e.g.
electrolytes) can move more freely across the bowel wall due to damage to the intestinal
lining. Excessive inflammation will cause this sort of change (e.g. hookworm infection,
- Increased motility where bowel movements are increased moving the gut contents through
quicker. As they move through at a faster rate, there is not enough time for water to be
absorbed well, resulting in a watery stool. This often occurs secondary to many disorders
that cause diarrhoea.
Kennel Management of Diarrhoea
Diarrhoea in dogs has many causes! The number of dogs affected in a kennel and the age of those
showing signs is usually a good clue as to the cause for the diarrhoea. If predominantly young dogs
are experiencing diarrhoea, it is likely due to an infectious agent (e.g. a virus, bacteria or parasite).
Sometimes infections can occur with multiple infectious agents!
This is because younger animals
have an immature immune system, may have experienced poor weaning practices or may not be up
to date with vaccination. Diarrhoea affecting all the dogs in the kennels, especially where adult
animals are also involved, is more likely to be due to inadequate sanitation practices in the kennels,
stress or diet related (e.g. over-consumption of food or a sudden change in diet).
Viral infections are more common in young, unvaccinated puppies than adult dogs.
rotavirus and parvovirus are the three main causes of viral diarrhoea in kennels.
Rotavirus can occur in dogs at any age but is more common in puppies less than 12 weeks old.
The virus is usually self-limiting and resolves within 5-7 days. Coronavirus also commonly occurs in
puppies but they are usually over 10 weeks of age. The diarrhoea can last up to 12 days with soft
stools persisting for a few weeks. These two viral infections destroy the cells of the intestinal lining
reducing the ability of the gut to absorb nutrients and water. Because of the local destruction they
cause, they can promote secondary infection with bacteria, parasites and even Parvovirus..
Canine parvovirusis more common in puppies (aged 6 weeks to 6 months) and unvaccinated adult
dogs. Assuming that puppies receive adequate colostrum from the bitch, this should provide
protection against parvovirus in the first few weeks of life. Parvovirus infection can be prevented
with a modified live vaccination with the first booster given as early as 6 weeks of age.
The virus causes diarrhoea by damaging the cells in the intestine responsible for producing and
maintaining a normal intestinal lining. As no new lining is produced, there is a loss of ability to
absorb nutrients and water, and the lining may shed. This viral infection is severe and puppies
present with vomiting, depression, fever, dehydration and foul smelling bloody diarrhoea.
the extensive damage it causes to the intestinal lining and its direct effect on suppressing the
immune system, these dogs can very quickly become septic and die. Treatment requires
hospitalisation, intravenous fluid therapy and various medications to treat secondary bacterial
infection and nausea.
Parvovirus is highly contagious and so affected animals should be isolated. The virus itself is very
hardy, resistance to most detergents, lasting in the environment 6-12 months.
Campylobacter, Salmonella, Clostridia and E. coli are among the bacterial agents most commonly involved in diarrhoea in kennels. They have several common characteristics:
- These bacteria are naturally present in the intestinal flora of dogs, but are not pathogenic as long
as the balance of the intestinal flora is maintained and the animal possesses its full immune
capacities. For example, a large number of epidemiological studies conducted in various countries on
hundreds of healthy dogs living in kennels have shown that the shedding of campylobacter was
regularly observed in more than 30% of animals, peaking around week 8. This healthy carriage rate is
43% in Australia, 32% in Switzerland, 26% in Spain, 37% in the USA, 29% in Sweden and 29% in
Contaminated food that is slowly defrosted at ambient temperature (poultry, pork, beef, cow’s milk,
carcasses and abattoir waste), faecal matter from infected animals or contaminated water are all
possible sources of infection.
The ability of this group of bacteria to cause diarrhoea in mainly young puppies or adults usually
occurs secondary to other conditions such as stress, concurrent disease (e.g. parvovirus infection)or
unhygienic conditions. Sudden dietary changes can cause disturbances in the gut flora leading to
overgrowth and infection by certain types of bacteria.
Some of these bacteria are zoonotic; meaning they can be transmitted to humans. Any dog
presenting with diarrhoea, especially where bacterial causes are suspected, should be isolated and
any humans in contact with the affected dogs should use personal protective equipment.
A large number of parasites can cause diarrhoea in a kennels environment, especially in young dogs..
Protozoan infections (e.g. Coccidiosis and Giardiasis)and nematode infections (e.g. roundworms,
hookworms and whipworms) are the parasitic diseases most often responsible for diarrhoea in a
Giardia is a chronic intestinal infection with a protozoa. Infection is common in dogs and cats and is
transmissible to humans. Transmission is usually from contamination of the environment with faeces
from affected animals. The cysts that are shed into the environment are very hardy persisting in
environments of high humidity and overcrowded kennels. The diarrhoea is chronic and intermittent,
with foul smelling watery stools often with mucus. Treatment of affected animals and the
environment using quarternary ammonium compounds is important to prevent re-infection and
spread to other animals.
Coccidiosis, although not as common as Giardia, is caused by small protozoan organisms (e.g.
Isospora) that infect puppies typically during weaning stress. They often cause severe diarrhoea,
weight loss and dehydration. Sanitation is very important in kennels to prevent spread, specifically
around ensuring faecal contamination of food and water sources is prevented.
Round worm infection, toxocariasis, is common in puppies. These worms are usually transmitted to
the puppies in utero via the placenta or through the mammary gland when feeding from the bitch.
The larvae can migrate to the lungs, liver and into the bloodstream from the gut. The larvae are
passed in the faeces of the pups and are easily transmitted in a kennel environment between dogs.
Young puppies affected don’t grow well and lose condition rapidly. They may also appear potbellied
and have diarrhoea with mucus visible. Treatment and prevention of roundworms is based on an
appropriate parasiticide protocol for all dogs in the kennel environment.
Roundworms are zoonotic and infections in humans can cause serious disease such as blindness due
to larval migrans.
Whipworms and hookworms are also responsible for mild gastroenteritis in young puppies and adult
dogs but are usually prevented with adequate anthelmintic treatment protocols.
Diarrhoea caused by Diet
The overconsumption of food overloads the gut and speeds up movement of gut contents.
Undigested food ferments leading to undesirable changes in the intestinal flora and large volumes of
fluid moving into the bowel, causing diarrhoea. Managing competition at feeding time to ensure no
one dog consumes a large quantity of food is important.
Low food digestibility
Food of low quality, too rich in fermentable fibre, say, is likely to draw large volumes of fluid into the
bowel and cause diarrhoea.
Transitions between diets
Dogs do not need variety in their diet and sudden dietary changes should be avoided. Where diet
must be changed, a gradual transition is recommended to avoid gastrointestinal upsets. Gradually
reducing the amount of old food and increasing the amount of new food is advised over a period of
7-10 days. A sudden change may cause significant disturbances to the intestinal flora causing