Issue Description Pythiosis is caused by Pythium insidiosum and
occurs most commonly in dogs and horses, but is also found in cats,
cattle, and humans. The disease is typically found in young, large
breed dogs. Pythium occupies swamps in late summer and infects dogs
who drink water containing it. Pythium insidiosum is different from
other members of the genus in that human and horse hair, skin, and
decaying animal and plant tissue are chemoattractants for its
Pythiosis occurs in areas with mild winters because the organism
survives in standing water that does not reach freezing temperatures.
In the United States it is most commonly found in the Gulf states,
especially Louisiana, but has also been found in midwest and eastern
states. It is also found in southeast Asia, eastern Australia, New
Zealand, and South America.
It is suspected that pythiosis
is caused by invasion of the organism into wounds, either in the skin
or in the gastrointestinal tract. The disease grows slowly in the
stomach and small intestine, eventually forming large lumps of
granulation tissue. It can also invade surrounding lymph nodes.
Symptoms Symptoms include vomiting, diarrhea,
depression, weight loss, and a mass in the abdomen. Pythiosis of the
skin in dogs is very rare, and appears as ulcerated lumps. Primary
infection can also occur in the bones and lungs.
Treatment Traditional treatment options for Pythium
infected dogs include surgical resection of infected tissues and
antifungal medications. Overall success when using one or more of
these treatment options is only +/- 25%. Recently the USDA has
approved an Immunotherapy treatment product. This product consists of
purified proteins derived from Pythium Insidiosum. These proteins are
injected into the infected patient in an effort to elicit an immune
response which will kill the invading Pythium. In horses this
treatment is successful in greater than 90% of cases, however, in
canine cases the success rate is nearer 50%. Work continues on a new
version of this product which will demonstrate a higher success rate