What are Xanthine Urinary Tract Stones?
Xanthine urinary tract stones can lead to xanthinuria when in the urine, also known as xanthine oxidase deficiency, a genetic disorder of xanthine accumulation. Xanthine related stones can also lead to Hyperxanthinuria when xanthine is present in the blood, interfering with serum uric acid.
If you find your cat crying or meowing while using the litter box, and making constant trips to urinate, she could have xanthine uroliths, or urinary tract stones. Uroliths can occur during the natural process of converting byproducts into uric acid. A variety of stones have been identified in felines and, depending on the mineral involved, a cat can develop a cysteine bladder stone, calcium phosphate stone, urate stone, calcium oxalate stone, struvite and, of course, xanthine. Each stone forms for a different reason, but in the case of xanthine urinary tract stones, the purine, xanthine, cannot be converted into uric acid with the required enzyme, xanthine oxidase.
Symptoms of Xanthine Urinary Tract Stones in Cats
Uroliths can be large or small, smooth or rough in texture. Therefore uroliths can cause a great deal of discomfort for your act. Small stones can obstruct the urinary flow and irritate the mucosal surface, whereas rough stone tear the inside of the urinary system, causing bleeding. The symptoms noted in the case of xanthine urinary tract stones in cats include the following:
- Hematuria: blood present in the urine
- Polyuria: frequent urination
- Vocalizing while urination
- Straining to urinate with or without the passing of urine
Hereditary Xanthine Urinary Tract Stones
There is no feline breed predisposition for xanthine urinary stones known to the veterinary world, but stones that have occurred naturally with no underlying cause are likely due to a congenital disposition.
Acquired/drug related Xanthine Urinary Tract Stones
High protein diets and taking the drug allopurinol can result in Xanthine urinary tract stones.
Causes of Xanthine Urinary Tract Stones in Cats
Xanthine urinary tract stone in cats are caused by the feline’s inability to convert the by-product of purine metabolism into uric acid by the xanthine oxidase enzyme. The inability to complete xanthine oxidases can be caused by the following:
- Hereditary predisposition
- A high protein diet
- The drug allopurinol
- Infrequent or incomplete urination
- Highly concentrated urine
- Imbalanced urine pH
Diagnosis of Xanthine Urinary Tract Stones in Cats
Diagnosis of Xanthine urinary tract stones in cats will begin with a review of your cat’s medical history and a discussion with the pet owner. Questions that your veterinarian might ask you to help diagnose the situation include:
- How often your cat goes to the litter box
- What happens when she/he goes to the litter box? Is there urine present? Does she strain to urinate or cry?
- What is your cat’s current diet?
- What medications is he/she currently taking?
After comparing notes, the veterinarian will proceed to conduct a physical examination, as some stones may be felt by palpating the feline’s bladder. Palpating, in this case, is the act of finding the bladder from the outside and using the sense of feel to identify something abnormal. Additional diagnostic work following the historical background and physical exam might include:
- Visual aids such as an ultrasound, X-ray, ultrasonography or urethrocystoscopy to detect location, size, number and the presence of a stone.
- A urinalysis that will show the presence of xanthine crystals in the sediment.
- Complete blood cell count
- Blood chemistry panel
- Urine culture to detect bacterial infection
Treatment of Xanthine Urinary Tract Stones in Cats
If the xanthine urinary tract stones in your cat are small enough, your veterinarian might recommend retrograde urohydropulsion. Retrograde urohydropulsion is a technique used to gently propel the stones from the urethra through use of a catheter and sterile fluid.
If the xanthine urinary stones are too large to be passed through the urethra, a surgical procedure called a perineal urethrostomy may need to be done. A perineal urethrostomy surgery is the creation of an opening between the skin and urethra, removing the stones manually.
The veterinarian may switch your cat to a low protein diet and change medications, if he or she believes these to be the cause of the developed stones. Increased water intake is usually advised to encourage urination and prevent the xanthine mineral from molding together.
Recovery of Xanthine Urinary Tract Stones in Cats
Your cat will recover within a day or two after the xanthine urinary tract stones have been removed. Pain medication and an antibiotic may be sent home with you if your cat has undergone a perineal urethrostomy surgery. Any prescribed medication should be given to your cat as directed and the entire treatment should be completed.
Xanthine urinary tract stones often reoccur in cats, so your veterinarian will likely schedule follow-up appointments on a monthly basis for your cat. The veterinarian may alter your feline’s diet, water intake and any prescribed medication she/he may be taking to accommodate the most recent examination.