What is Pythiosis?

Pythiosis is a disease caused by water mould named Pythium insidiosum. This disease is a problem chiefly for dogs and horses, but the fungi can infect humans and other animals such as horses, cattle and cats. When dogs are infected with Pythium insidiosum, it often affects lymph nodes and the gastrointestinal system. In other animals, skin problems are more common. Young dogs from large breeds are more prone to Pythiosis than other dogs.

Pythium insidiosum is different from the other fungi found in the genus Pythium, since Pythium insidiosum have zoospores that are chemically attracted not only to decaying plant tissue, but to animal skin, hair and decaying tissue as well.

What is the difference between Pythiosis and Phycomycosis?

Phycomycosis is a condition that can be caused by a wide range of different molds and fungi, including Pythium insidiosum. Pythiosis is the most common form of Phycomycosis; other examples of Phycomycosis types are Zygomycosis and Lagenidiosis.

Pythiosis occurrence and transmission

Pythium insidiosum mould is found in North America, South America, South-East Asia, Eastern Australia, and New Zeeland. It lives in parts of the world where the winters are mild, since it needs standing water that does not freeze to survive. In the United States, Pythium insidiosum is most commonly found in the warm Gulf States (particularly Louisiana), but have also been detected in Eastern and Midwest states.

Pythium insidiosum lives in swamps and other forms of standing water and is transmitted to dogs when they drink the water. It might also be possible for the Pythium insidiosum mould to infect the dog through wounds, and some studies indicate that wounds in the gastrointestinal tract might be is necessary to catch Pythiosis by drinking contaminated water.

Pythiosis symptoms in dogs

When Pythium insidiosum gains entry to a dog, it will start to slowly grow in the stomach and the small intestine of the animal. Eventually, big lumps consisting of granulation tissue will develop in the stomach and small intestine, and the disease can spread to nearby lymph nodes. In dogs, the most common symptoms of Pythiosis are related to the stomach, such as vomiting, diarrhoea and weight loss. The can also be noticeable mass in the abdomen. Pythiosis in dogs can make them weak and depressed. If Pythium insidiosum infects the skin of a dog, it can cause ulcerated lumps. This form of Pythiosis is very rare in dogs, but it does occur one in a while. Although uncommon, Pythiosis can also occur in the lungs and bones of dogs.   

Pythiosis treatment for dogs

The standard Pythiosis treatment for dogs will often involve surgery and is quite complicated and lengthy. Surgery must be accompanied with antifungal drugs for at least 2-3 months, such as Itraconazole and Terbinafine hydrochloride. Unfortunately, postoperative recurrence is not uncommon in dogs infected with Pythiosis. Antifungal drugs will often have only a limited effect.

When humans are infected with Pythium insidiosum more alternatives are available, and veterinarian experts and researchers might be able to benefit from the comparative success reached on the human side of the medical field in their search for more efficient Pythiosis treatments for dogs. Humans have for instance been successfully treated with Caspofungin. The problem with Caspofungin is that it is very expensive, thereby out of reach for many dog owners. In both humans and horses with Pythiosis, immunotherapy have proven successful in the past and this might be a possible Pythiosis treatment for dogs as well.

Fungal Infections in dogs: (click for more info)
Blastomycosis in dogs
Cryptococcosis in dogs
Histoplasmosis in dogs
Phycomycosis in dogs
Pythiosis in dogs
Ringworm in dogs
Sporotrichosis in dogs