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Struvite stones are a common urological disease in cats that can cause significant discomfort and serious health complications. A thorough knowledge of this condition allows pet owners to take preventive measures to support their cats.
Types of urinary stones
The most common are struvite stones, calcium oxalate stones and mixed types (struvite-calcium oxalate stones). Struvite stones mainly form when the urine is alkaline (high pH value) and at the same time there are high concentrations of minerals such as phosphorus or calcium. Vegetable components in feed can increase the pH value. However, if the urine is very acidic (low pH), calcium oxalate crystals can form. Calcium oxalate stones are more commonly found in animals aged 2 years and older, while struvite stones also occur in younger animals (1–2 years).
Causes of struvite stones
Struvite stones, also known as magnesium-ammonium-phosphate stones, are caused by an excessive concentration of magnesium, ammonium and phosphate in the cat's urine. This imbalance can be caused by various factors including:
- Diet: An unbalanced or excessively alkaline diet that is rich in minerals (magnesium and phosphate) can promote the formation of struvite stones.
- Low fluid intake: Low fluid intake can lead to increased concentrations of minerals in the urine, including magnesium, ammonium and phosphate. If urine is too concentrated, the risk of struvite stone formation increases.
- Urinary tract infections: Bacterial infections of the urinary tract can lead to an alkaline pH shift, which promotes the growth of struvite stones.
- Underlying diseases: Underlying health conditions such as Feline Lower Urinary Tract Disease (FLUTD) or kidney dysfunction can increase the risk of developing struvite stones.
Symptoms of struvite stones
Urinary stones themselves do not always cause problems. However, if inflammation and infections occur as a result of mucous membrane injuries, the animals have symptoms. These are particularly well hidden from people by cats. The following signs indicate a problem and should be checked by a veterinarian. Symptoms of struvite stones can vary from cat to cat, but typical signs include:
- Frequent urination or inability to pass urine
- Pain and discomfort when urinating (dysuria)
- Blood in the urine (hematuria)
- Behavioral changes such as uncleanliness or restlessness
- From loss of appetite to signs of kidney failure in severe cases
If an animal has a massive bladder infection or the urinary tract is even blocked by the urinary stones, the signs can no longer be overlooked:
- Frequent, often unsuccessful attempts to pass urine
- Blood in the urine
- Expression of pain while using the litter box
- Fever, loss of appetite, vomiting
Since these symptoms can be signs of a life-threatening emergency, the animal needs to be taken to the vet urgently.
Diagnosis of struvite stones
Since there are different causes of bladder infections and different types of stones, each of which needs to be treated in a different way, the cause of the symptoms should definitely be determined by a veterinarian. Diagnosis of struvite stones is usually made through a thorough examination of the cat's urine. The vet will take a urine sample and examine it for the presence of crystals, particularly struvite crystals. An imaging test such as an X-ray or ultrasound may also be performed to determine the size and location of the stones in the urinary tract.
Treatment options for struvite stones
Treating struvite stones in cats may involve a variety of approaches depending on the severity of the condition. Common treatment options include:
- Hydration: Increasing fluid intake through wet food or the use of drinking fountains can help flush the urinary tract and reduce the formation of struvite stones.
- Drug therapy: In some cases, medications may be given to regulate the pH of urine or to treat infections that contribute to the formation of struvite stones.
- Surgical procedures: Larger or stubborn stones may require surgical removal to restore urine flow and prevent further complications.
- Diet management: A special diet that controls urine pH and reduces magnesium and phosphate levels can help control and prevent the growth of struvite stones. There are special complete feeds for this, but also suitable supplementary feeds.
Expert knowledge
Calcium oxalate stones usually need to be removed surgically, but struvite stones can be dissolved by acidifying the urine. This is possible, for example, by supplementing with DL-methionine. Methionine is a urinary acidifying amino acid that helps lower urine pH. In order to dissolve struvite stones and prevent new formation, the pH value should be in the acidic range of 6.2 to 6.4 (below 6.5).
In addition to sufficient water intake, herbal ingredients can support the treatment. Nettle, goldenrod or field horsetail e.g. B. stimulate urine excretion naturally without affecting the electrolyte balance. Cranberry (traditionally used for bladder infections) is said to prevent bacteria from settling in the urinary tract and promote their flushing out. The bladder mucosa is often damaged by sharp-edged crystals and stones as well as inflammation. Glucosaminoglucans (GAGs) can supplement the defective protective layer of the bladder wall. If the protective layer of the bladder is intact, germs no longer settle so easily.
Struvite stones are a serious condition in cats that require timely diagnosis and appropriate treatment. Switching to a balanced diet, controlling urine pH, and increasing fluid intake can help prevent the growth of struvite stones. If struvite stones are suspected, a veterinarian should be consulted immediately to make an accurate diagnosis and develop an appropriate treatment strategy. Regular monitoring and veterinary care are critical to ensure the welfare and long-term health of cats with struvite stones.
