Pythiosis in Dogs: Beware of Warm, Stagnant Water

Many dogs love nothing more than a good splash in a pond or creek, especially on a hot summer day. While pet water safety is important for everyone, residents of North Carolina and other southeastern US states face a particular danger. 

Pythiosis, a variety of mold that thrives in warm, still water, can have devastating effects on your dog’s health. Though relatively uncommon, it’s aggressive, difficult to treat, and can be deadly if not caught early. Here’s what dog parents need to know about this waterborne illness and how to help protect their pets.

What Is Pythiosis

Pythiosis is caused by a microorganism called Pythium insidiosum. It acts like a fungus but is actually a type of water mold found in warm, slow-moving freshwater environments like ponds, lakes, and swamps. 

Dogs typically become infected by drinking or swimming in contaminated water, especially if they have any open cuts or wounds. Once inside the body, Pythium can cause serious infections of the skin or GI  tract.

This disease is most common in regions where temperatures stay warm for longer stretches of the year, but it can pop up anywhere conditions are right. Expectedly, Pythium infections spike in the summer. 

Symptoms of Pythium Infection

Pythiosis can present in two major forms: cutaneous (skin) or gastrointestinal. 

Cutaneous pythiosis:

• Sores or wounds that won’t heal
• Firm lumps or masses under the skin
• Ulcerated or draining lesions

Gastrointestinal pythiosis:

• Vomiting and/or diarrhea 
• Weight loss
• Blood in stool
• Abdominal pain or swelling
• Lethargy

Unfortunately, these symptoms usually take months to appear and can resemble other, more common conditions, so pythiosis can be difficult to diagnose early without specific testing.

Risk Factors

Pythiosis is most common in hunting or working dogs that spend time in or around swamps, marshes, and lakes. However, any water-loving dog is at risk of exposure. 

Pets with open cuts or sores or those prone to drinking lake water should be monitored closely while outdoors. 

Pythiosis Prognosis + Treatment

Pythiosis is aggressive and spreads quickly. If left untreated, organ failure, malnutrition, and sepsis are imminent. 

Because the symptoms of an infection can mimic other conditions, your vet will likely have to confirm pythiosis through imaging, biopsies, or specialized lab testing. Depending on how far the infection has progressed, treatment may involve the surgical removal of affected tissue, antifungal medications, or supportive care to manage symptoms. 

Only about 10% of dogs are cured through medication alone, making an early surgical intervention the most effective treatment by far.

Protect Your Dog

There’s currently no vaccine for pythiosis, so prevention comes down to awareness and avoiding risky environments. Here are a few ways to reduce your dog’s risk:

• Don’t allow your dog to wade or swim in warm, still bodies of freshwater, especially during the hottest parts of the year. 
• Bring plenty of clean water on outings so your dog isn’t tempted to drink from ponds, lakes, or swamps.
• Check your dog for open wounds and avoid water exposure until any cuts or sores are healed. 
• Follow up any outdoor swimming with a bath to remove potentially harmful microorganisms from their coat. 

If your dog is experiencing persistent gastrointestinal symptoms or skin abnormalities, don’t hesitate to contact your vet to definitively rule out pythiosis. Early detection and treatment are crucial for a better prognosis.