Tuesday, February 8, 2011

326. pug with recurrent infected struvite stones - case report for vet students and owners

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Case study: Infection-induced struvite uroliths in the dog
Pug, Male, 2 and half years. Bladder stones removed by Vet 1 around one year ago. Dog was on Hill's SD on one month, CD for 3 months. The complaint was dysuria (straining to pee) for the past few days.

"Why?" the lady who had kept 3 pugs to an old age, had no urinary stone problems. The black pug lived up to 18 years of age. (3 pugs were fed home-cooked food by the mother but this 4th pug was given dry dog food as her mother had passed away.

However, she anticipated no problem after bladder stone removal by Vet 1. "Why did the vet not advise follow-up? I stopped giving the Hills' Prescription diet as my dog was showing allergy and feed home-cooked rice and meat." Her father asked me at another visit: "Is it because the vet (Vet 1) had not completely removed all urinary stones?" Residual stones could cause a recurrence but stones do recur even after complete stone removal.

urethral obstruction - used smaller catheter. pug drinks little. toapayohvets, singaporeA real case will interest the vet student as it can be sleep-inducing to read through the several hundreds of pages of urinary stones in dogs in various text books and the internet. The following case will help to explain to students the approach to one approach to the medical treatment of struvite uroliths in the dogs at Toa Payoh Vets.

There are 3 scenarios mentioned in the above website.
1. Medical dissolution of struvite uroliths in dogs
2. Prevention of infection-induced struvite uroliths
3. Prevention of sterile struvite uroliths in dogs

This pug has 1 and 2 and so the medical treatment (as contrasted to surgical treatment) is discussed below.
On 26.1.11, the pug strained to pass urine.
Urine Test results from lab:
Urine: amber & turbid
pH= 8.0 (5-8)
SG = 1.010 (1.005 - 1.030)
Bilirubin ++
Blood ++++
Casts Nil
Bacteria ++ Crystals
triple phosphate +,
calcium oxalate occasional, amorphous phosphate ++
Calcium oxalate crystalluria. Collect fresh urine and analyse within 30 minutes. If persistent and in breeds (Bichon Frise, Miniature Schnauzer, Yorkshire Terrier, Shih Tzu, Lhasa Apso), discontinue diets that promote formation of acidic urine and consult recommendations for Calcium oxalate prevention. Struvite crystalluria is insignificant if the dog has negative urine cultures. However this pug had bacteria in the urine. Struvite is also known as triple-phosphate, ammonium phosphate and urease stones and are invariably associated with urinary tract infections in people and dogs with alkaline urine (pH > 7.2).
Blood Test results from the lab:
% Absolute
WBC normal range. Biochemistry normal Neutrophils 71%
Lymphocytes 18%
Monocytes 9%
Eosinophils 0.2%
Basophils 1.8% 11.50
No obvious urinary stones seen in the kidney, bladder or os penis. The alkaline pH, bacteria in the urine and struvite crystals indicated a recurrence of the urinary stone formation with urinary tract infection. The Owner wants medical (conservative) treatment. Acidifying tablets* (1 tablet 1 x/day for 10 days), canned CD diet and trimethoprim antibiotics were prescribed.
*1 tablet/5 kg twice a day is recommended by manufacturer. The pug is 9.5 kg and would be getting 2 tablets 2x/day in theory.

Feb 7, 2011. Owner is in her 30s and has good medical knowledge as she works in the medical profession. She probably does internet research on urinary stones in the dogs. She e-mailed to me the follow dipstick result I had asked her to do at home.
Feb 7, 2011

Greetings Dr Sing

Happy New Year to you, your family and your folks at Toa Payoh Vets! I had done a urine dipstix for XXX and results are as follows:
Leukocytes: Neg
Nitrate: Neg
Urobilinogen: 0.2 Protein: Neg
pH: 5.0-6.0
Blood: Neg Ketone: Neg
Bilirubin: Neg
Glucose: Neg

He's so much better with his urination though at times, his post void can be slightly delayed (meaning he puts his leg down quite some time even when there seems to be no more urine).

As I will be leaving for overseas for a week on Wed morning, do you need me to bring XXX over tomorrow?

Thanks and regards

The urine was not alkaline as on the first day of consultation. pH was 8.0 then. Dipstick results are not reliable but is easy for the owner to do. I advised a review of dog, urine bacterial culture and test 3-4 weeks after the first visit and get a urine test done (via catherisation since it is difficult for the owner to collect a mid-stream urine into the urine collection container! The pug would stop peeing when she tried to collect urine.)

On Feb 8, 2011, the lady owner came for acidurin tablets for another 20 days and said that since the dog does not have much difficulty in urination, the trimethoprim tablets must be effective and therefore there is no need for a urine antibiotic-sensistivity test.

1. Treatment: Control urinary tract infections. Select antibiotics based on urine bacterial culture and susceptibility results. Culture urine during therapy to verify effectiveness of antibiotics.

With additional recurrent infections, antibiotics for 4 weeks, then 1/2 daily doses for 9-12 months, 4-weekly urine cultures.

2. Acidify urine: medication
3. Diet which promotes acidic urine. These have reduced protein, phosphorus and magnesium.
4. Monitoring: Urine culture and urinalysis in 1 month and 3-monthly.

5. X-ray: Every 6 months or sooner if the patient has recurrent urinary tract infection symptoms*.

*excessive vulval licking, urinating in the house, pollakiuria, haematuria etc.

*identify and eradicate anatomic abnormalities (vaginourethrocystoscopy, contrast vaaginourethrocystography and ultrasonography) and functional (urine cortisol to creatinine ratio, serum biochemical and thyroid profiles and neurological exam) risk factors for recurrent infections.

Note 1: struvite crystalluria is insignificant if the dog has negative urine cultures. However this case has bacteria in the urine.

Note 2: Calcium oxalate crystalluria. Collect fresh urine and analyse within 30 minutes. If persistent and in breeds (Bichon Frise, Miniature Schnauzer, Yorkshire Terrier, Shih Tzu, Lhasa Apso), discontinue diets that promote formation of acidic urine and consult recommendations for Calcium oxalate prevention.

An American veterinary school (webpage not available to the members of the public) that does urolith analysis for Hills' samples, recorded that medical dissolution of struvite uroliths with Hills' s/d canine was 100% effective after 3-6 weeks for sterile struvite uroliths and 8-12 weeks with effective antibiotics for infection-induced struvite uroliths. It seems that this institution favours medical treatment (i.e. no surgery to remove stones).

Immature dogs should not be given low protein s/d for a long term. However, a short-term use with antibiotics has rapidly dissolved infection-induced struvite uroliths in 9-12 days without adverse events.

Owner/patient compliance when feeding s/d is easily determined with a urine SG (mean = 1.008+/-0.003) and pH (mean =6.2+/-0.7). If no urine sample, serum urea nitrogen is a reliable marker (mean 3.5+/- 2.4 mg/dl). The s/d diet is high in fat and high fat is a risk factor for pancreatitis.

Female Miniature Schnauzers and others with hyperadrenocortisicism risk pancreatitiis and UTI that includes urease-producing uropathogens. Respond by discontinuing s/d diet, maintain hydration if vomiting/pancreatitis occur. Consider alternative that also acidify urine eg. canned w/d Canine) to correct both diseases. 26% of canine nephroliths are composed of struvite. They can be dissolved medically as in bladder stones but this takes a much longer time due to reduced kidney function, reduced urine production and reduced nephrolith dwell time in therapeutically undersaturated urine.

Approaches to treatment. Medical or surgical treatment? For large stones and urethral obstruction, I advise surgery to remove all the stones after antibiotic treatment. Stones do recur even after complete stone removal in some cases. Many Singapore owners do not comply with medical treatment and the follow-up reviews (urine tests 3-monthly, X-rays 6 monthly). I presume it is due to economics and lack of time. Surgery should be done only after effective antibiotic treatment rather than immediately.

In this case, the pug drinks little but drinks more after going outdoors for exercise. "Try adding some ice-cubes to the water," I said to the lady who loves pugs only. Regular urine monitoring will be needed for the next 6 months and no dry dog food or dog treats and biscuits must be given. The lady owner was satisfied with the outcome that the pug was no longer taking a long time to pee.

Urine-marking in male dogs may or may not lead to urinary tract infections as the male dog with-holds urine to have sufficient amount to mark the territory. The alpha male dog pees until the last drop and even tries to pee when there is no more urine in the bladder. Neutering the dog may help prevent urinary tract infection. The lady owner was not keen on neutering.
Old Golden Retriever passes smelly urine with blood. A gigantic bladder stone. toapayohvets singaporeStones submitted for analysis in one female golden retriever by Toa Payoh Vets showed magnesium ammonium phosphate (struvite) 95% in the stone and 100% in the shell with zero in the nidus and surface. Calcium phosphate carbonate was 5% inside the stone. More case studies, goto: urinary tract problems in dogs and cats

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