Fungal Infection of the Lower Urinary Tract in Dogs

Fungal infections of the lower urinary tract in dogs are generally caused by an overgrowth of Candida fungal yeasts. Although candida yeasts are normally present in the body as well as on the skin circumstances can promote overgrowth of these organisms and disrupt the natural functioning of the body. When this occurs in the lower urinary tract it causes an infection which can become progressively more uncomfortable for your canine companion.

A lower urinary tract infection caused by an overgrowth of a fungal yeast in the Candida genus. Fungal infections of the lower urinary tract often are asymptomatic, and may be uncovered when diagnosing another issue or during regular veterinary check-ups.

Dogs with either fungal or bacterial urinary tract infections may show no outward symptoms. When symptoms do present, owners may see any or all of the following signs:

• Cloudy or foul-smelling urine
• Hematuria (blood in urine)
• Inappropriate urination in housetrained dogs
• Lethargy
• Loss of appetite
• Nausea
• Pain or straining during urination
• Tenderness or pain in the bladder area

These symptoms may also indicate a more serious condition, Crystalluria, and should be evaluated by a veterinarian. If palpable tightness in the abdomen or inability to urinate is present, the symptoms should be treated as an emergency.

Types 

Most fungal infections in the lower urinary tract in dogs are caused by a species of fungal yeast in the Candida genus. This is the same genus of yeast that is the culprit in the majority of cases of thrush, yeast infections of the skin, and vaginal infections in both canines and humans. It is extremely rare for a fungal infection of the lower urinary tract to be caused by any other yeasts or fungi.

The fungal yeasts responsible for almost all lower urinary tract infections are in the genus Candida. These yeasts are normally present in the body as well as on the skin, however, many circumstances can promote overgrowth in these organisms which can cause disruptions in the proper functioning of the compromised system. In the case of an overgrowth of Candida in the lower urinary tract (the urethra, prostate and bladder) symptoms will mirror those of a bacterial infection. Conditions that may contribute the overgrowth of Candida yeasts can include, but are not limited to:

• Antibiotic use 
• Corticosteroid use
• Diabetes
• Dietary imbalance
• Urinary catheter
• Weakened immune response due to a congenital disorder, or acquired disease or disorder

In order to make a diagnosis your veterinarian will ask for a full history of the animal, as well as a general physical exam, taking particular note of any abdominal swelling or pain. A urinalysis will be required and a complete blood count and biochemistry profile may also be ordered to rule out any more serious or underlying conditions. The preferred method for urine collection in canines is cystocentesis, which involves inserting a sterile needle through the abdomen and into the urinary bladder to extract a clean sample. Your veterinarian will then examine the overall appearance of the sample as well as it’s other physical properties. A culture will usually be ordered at that point to determine if there is indeed an infection and whether it is bacterial or fungal in nature. In some circumstances, an x-ray or ultrasound of the abdomen may be warranted to rule out sediment in the bladder, enlarged prostate, or structural concerns with the kidneys, bladder, or urethra. 

Fungal infections of the lower urinary tract often are asymptomatic, and may be uncovered when diagnosing another issue or during regular veterinary check-ups.

Once an infection of the lower urinary tract is uncovered it can take a day or two for culture results to be relayed to your veterinarian. As the majority of lower urinary tract infections are bacterial in nature your veterinarian may opt to start your dog on a broad spectrum antibiotic while they wait for the results. Treatment or management of any underlying triggers (such as diabetes or the use of corticosteroids) will be initiated as soon as feasible, often before the results from the culture have been made available. Sometimes treating the underlying cause is enough to resolve the problem, but in many cases additional steps will need to take place. Once the results of the culture are obtained your veterinarian may have you cease antibiotic treatment and begin antifungal treatment instead. The most common antifungal medication used to treat Candida infestations is Fluconazole, although other antifungals in the same family have been successfully utilized as well. Probiotics may be recommended by your veterinarian as well to rebalance the microflora in the recovering digestive system.

During the recovery period it is best to have a comfortable and quiet space available for your companion to recuperate with plenty of access to food and water if they need it. Your pet may be asymptomatic during all or part of their treatment, and do not need to have their activity restricted unless other signs of distress are noted. Infections by the Candida fungus are zoonotic and can be transmitted to humans. The very young, the very old and those with compromised immune responses should avoid contact with the infective yeast to be prevent transmission.  Antifungal treatments often take several weeks to completely clear up an infection and your veterinarian may request that you bring your pet in for further urine testing and cultures both during treatment and after. Although some dogs may require lifelong treatments to manage outbreaks the overall prognosis for yeast infections caused by the Candida fungus is generally quite good.