How would you manage the urocystoliths in this puppy?
The objectives of management of infection-induced uroliths in immature or mature dogs include:
- relief of obstruction to urine outflow when necessary.
- elimination of existing uroliths
- eradication or control of urinary tract infection.
- and prevention of recurrence of UTI and uroliths.
Surgery has been the traditional approach for management of all types of uroliths in young dogs. However, we have successfully
used a combination of a calculolytic diet (Prescription Diet Canine s/d, Hill's Pet Nutrition) and antimicrobial drugs to
dissolve infection-induced uroliths in several immature dogs. One example was a 9-week-old male mixed-breed dog with a vesicourachal
diverticulum, urethral stricture, Staphylococcus intermedius urinary tract infection and multiple struvite urocystoliths.
Photo 1: Uroliths caught in an aquarium fish net placed in a stream of urine during voiding.
In that dog, the urocystoliths dissolved within nine days of initiation of calculolytic diet and antimicrobial (amoxicillin
and clavulanic acid) treatment; the diet was discontinued on day 10. A slight reduction in serum albumin concentration (from
approx. 3.2 to 2.7 g/dl) was observed during the 10-day interval of dietary treatment. The serum albumin concentration returned
to reference values soon after the pup resumed eating a normal growth diet. The vesicourachal diverticulum and urethral stricture
spontaneously resolved over the next few months.
When considering modified diets designed for use in adult dogs to treat young growing dogs, expected benefits must be evaluated
in light of potential risks. Because it is not formulated to meet the nutrient requirements of growing dogs, we do not recommend
feeding the canine calculolytic diet to immature dogs for more than a few weeks! If the calculolytic diet is used, we recommend
serially monitoring body weight, serum albumin concentration and PCV for evidence of protein/calorie malnutrition. If substantial
reductions in these parameters are observed, appropriate adjustments in dietary management should be made. If dietary therapy
is associated with sufficient reduction in the size of urolith urocystoliths so that they could pass through a distended urethra,
they may be removed by voiding urohydropropulsion.
How would you prevent urolith recurrence in this pup?
With appropriate medical and/or surgical therapy to eliminate the uroliths, the short-term prognosis for this puppy is good.
Eradication and/or control of UTI caused by urease-producing bacteria are the most important factors in preventing recurrence
of struvite uroliths in this patient. This type of stone cannot recur in the absence of infection with urease-producing microbes.
By eliminating the infection, the puppy can be fed a balanced diet designed for growth. However, if the UTI persists or recurs
following therapy, further evaluation of the puppy with the goal of identifying and correcting factors that predispose to
infection should be recommended.
What about the association of the Shih Tzu breed and calcium oxalate uroliths? When considering prognoses, it is important
to keep the significance of risk factors in perspective. When used in a qualitative (rather than a quantitative) way, the
significance of risk factors should not be assigned an "all-or-none" or "always-or-never" interpretation.
In many situations, specific risk factors only contribute a limited role to the development of urolithiasis. Furthermore,
identification of one event in a chain of etiological events is not the same as identifying the entire etiological chain.
Other than stating that the Shih Tzu breed has been identified as a risk factor for calcium oxalate uroliths, it would not
be reasonable to forecast that this puppy is likely to develop calcium oxalate uroliths. In this context, the observations
that calcium oxalate uroliths tend to be associated with advancing age and gender (higher risk in males) are relevant.