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  • Author or Editor: Carl L. Koehler x
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Abstract

Objective—To investigate the biomechanics of cervical vertebral motion units (VMUs) before and after a ventral slot procedure and after subsequent pin-polymethylmethacrylate (pin-PMMA) fixation and to assess the use of smooth and positive-profile threaded (PPT) pins in pin-PMMA fixation and intravertebral pin placement.

Sample Population—Cervical portions (C3 through C6 vertebrae) of 14 cadaveric canine vertebral columns.

Procedure—Flexion and extension bending moments were applied to specimens before and after creation of a ventral slot across the C4-C5 intervertebral space and after subsequent smooth or PPT pin-PMMA fixation at that site. Data for the C3-C4, C4-C5, and C5-C6 VMUs were compared among treatments and between pin types, and pin protrusion was compared between pin types.

Results—Compared with values in intact specimens, ventral slot treatment increased neutral zone range of motion (NZ-ROM) by 98% at the treated VMUs and appeared to decrease overall ROM at adjacent VMUs; pin-PMMA fixation decreased NZ-ROM by 92% at the treated VMUs and increased overall NZ-ROM by 19% to 24% at adjacent VMUs. Specimens fixed with PPT pins were 82% (flexion) and 80% (extension) stiffer than smooth–pin-fixed specimens. Overall, 41% of pins protruded into foramina; PPT pins were more likely to protrude into transverse foramina.

Conclusions and Clinical Relevance—Results indicated that fixation of a cervical VMU alters the biomechanics of adjacent VMUs and may contribute to degeneration of adjacent intervertebral disks. Use of threaded pins may lower the incidence of pin loosening and implant failure but enhances the likelihood of transverse foramina penetration. ( Am J Vet Res 2005;66:678–687)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether breed, age, sex, or reproductive status (ie, neutered versus sexually intact) was associated with the apparent increase in prevalence of calcium oxalate (CaOx) uroliths and the decrease in prevalence of magnesium ammonium phosphate (MAP) uroliths in cats over time.

Design—Case-control study.

Animals—Case cats consisted of cats with CaOx (n = 7,895) or MAP (7,334) uroliths evaluated at the Minnesota Urolith Center between 1981 and 1997. Control cats consisted of cats without urinary tract disease admitted to veterinary teaching hospitals in the United States and Canada during the same period (150,482).

Procedure—Univariate and multivariate logistic regression were performed.

Results—British Shorthair, Exotic Shorthair, Foreign Shorthair, Havana Brown, Himalayan, Persian, Ragdoll, and Scottish Fold cats had an increased risk of developing CaOx uroliths, as did male cats and neutered cats. Chartreux, domestic shorthair, Foreign Shorthair, Himalayan, Oriental Shorthair, and Ragdoll cats had an increased risk of developing MAP uroliths, as did female cats and neutered cats. Cats with CaOx uroliths were significantly older than cats with MAP uroliths.

Conclusions and Clinical Relevance—Results suggest that changes in breed, age, sex, or reproductive status did not contribute to the apparent reciprocal relationship between prevalences of CaOx and MAP uroliths in cats during a 17-year period. However, cats of particular breeds, ages, sex, and reproductive status had an increased risk of developing CaOx and MAP uroliths. (J Am Vet Med Assoc 2000;217:520–525)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine frequency of and interval until recurrence after initial ammonium urate, calcium oxalate, and struvite uroliths in cats and whether breed, age, or sex was associated with increased risk for urolith recurrence.

Design—Case-control study.

Animals—4,435 cats with recurrent uroliths.

Procedures—To identify recurrence of uroliths in cats for which uroliths were submitted for analysis at the Minnesota Urolith Center in 1998, the facility's database was searched for urolith resubmissions from the same cats between 1998 and 2003. Risk factors and differences in mean interval until recurrence were assessed.

Results—Of 221 cats with ammonium urate uroliths in 1998, 29 (13.1%) had a first and 9 (4.1%) had a second recurrence. Mean interval until recurrence was 22 and 43 months for the first and second recurrence, respectively. Of 2,393 cats with calcium oxalate uroliths in 1998, 169 (7.1%) had a first, 15 (0.6%) had a second, and 2 (0.1%) had a third recurrence. Mean interval until recurrence was 25, 38, and 48 months for the first, second, and third recurrence, respectively. Of 1,821 cats with struvite uroliths in 1998, 49 (2.7%) had a first and 3 (0.2%) had a second recurrence. Mean interval until recurrence was 29 months for first and 40 months for second recurrences.

Conclusions and Clinical Relevance—These results provided insights into the frequency of urolith recurrence in cats. Because some uroliths associated with recurrent episodes probably were not submitted to our facility, our data likely represented an underestimation of the actual recurrence rate.

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in Journal of the American Veterinary Medical Association

Summary

A technique called voiding urohydropropulsion has been developed that facilitates nonsurgical removal of urocystoliths. Voiding urohydropropulsion was performed in 11 dogs and 10 cats with urocystoliths. Urocystoliths were completely removed from 15 of 21 animals (5 female dogs, 3 male dogs, 5 female cats, and 1 male cat). The number of uroliths removed from any animal varied between 1 and 983. The mean time required to complete voiding urohydropropulsion in the 15 animals from which all uroliths were completely removed was 22 minutes. In 6 animals (2 female dogs, 3 female cats, and 1 male cat), not all urocystoliths were removed. Visible hematuria was induced in all animals as a consequence of voiding urohydropropulsion. In dogs, visible hematuria resolved within 4 hours. Dysuria was not induced by this technique in dogs. In many cats, visible hematuria and dysuria persisted for 1 to 2 days. One male cat developed urethral obstruction after we failed to remove a urolith from the bladder. The urolith was returned to the urinary bladder, and subsequently removed by cystotomy. Voiding urohydropropulsion is a simple and effective method that should be considered for removal of small urocystoliths from dogs and cats before cystotomy is performed.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify dietary factors in commercially available canned foods associated with the development of calcium oxalate (CaOx) uroliths in dogs.

Animals—117 dogs with CaOx uroliths and 174 dogs without urinary tract disease.

Procedure—Case dogs were those that developed CaOx uroliths submitted to the Minnesota Urolith Center for quantitative analysis between 1990 and 1992 while fed a commercially available canned diet. Control dogs were those without urinary tract disease evaluated at the same veterinary hospital just prior to or immediately after each case dog. A content-validated multiple-choice questionnaire was mailed to each owner of case and control dogs with the permission of the primary care veterinarian. Univariate and multivariate logistic regressions for each dietary component were performed to test the hypothesis that a given factor was associated with CaOx urolith formation.

Results—Canned foods with the highest amount of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, or moisture were associated with a decreased risk of CaOx urolith formation, compared with diets with the lowest amounts. In contrast, canned diets with the highest amount of carbohydrate were associated with an increased risk of CaOx urolith formation.

Conclusions and Clinical Relevance—Feeding canned diets formulated to contain high amounts of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, and moisture and a low amount of carbohydrate may minimize the risk of CaOx urolith formation in dogs. (Am J Vet Res 2002;63:163–169)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To identify factors in dry diets associated with the occurrence of calcium oxalate (CaOx) uroliths in dogs.

Animals—600 dogs with CaOx uroliths and 898 dogs without urinary tract diseases.

Procedure—Univariate and multivariate logistic regression were performed.

Results—Compared with diets with the highest concentrations of sodium, dry diets with the lowest concentrations of sodium, phosphorus, calcium, chloride, protein, magnesium, or potassium were linearly associated with increased risk of CaOx urolith formation. Significant nonlinear associations between increased occurrence of CaOx uroliths and urine acidifying potential and low moisture content were observed. Significant nonlinear associations between decreased occurrence of CaOx uroliths and carbohydrate and fiber contents were observed. A significant association between the occurrence of CaOx uroliths and dietary fat was not observed.

Conclusions and Clinical Relevance—Results suggest that dry diets formulated to contain high concentrations of protein, calcium, phosphorus, magnesium, sodium, potassium, and chloride may minimize formation of CaOx uroliths. In addition, comparison of risk and protective factors of various diet ingredients fed to dogs with CaOx uroliths suggests that although similar findings were observed in canned and dry formulations, in general, greater risk is associated with dry formulations. However, before these hypotheses about dietary modifications are adopted by food manufacturers, they must be investigated by use of appropriately designed clinical studies of dogs with CaOx urolithiasis. (Am J Vet Res 2002;63:330–337)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To identify dietary factors associated with the increase in occurrence of calcium oxalate (CaOx) uroliths and the decrease in occurrence of magnesium ammonium phosphate (MAP) uroliths in cats.

Design—Case-control study.

Animals—173 cats with CaOx uroliths, 290 cats with MAP uroliths, and 827 cats without any urinary tract diseases.

Procedure—Univariate and multivariate logistic regression were performed.

Results—Cats fed diets low in sodium or potassium or formulated to maximize urine acidity had an increased risk of developing CaOx uroliths but a decreased risk of developing MAP uroliths. Additionally, compared with the lowest contents, diets with the highest moisture or protein contents and with moderate magnesium, phosphorus, or calcium contents were associated with decreased risk of CaOx urolith formation. In contrast, diets with moderate fat or carbohydrate contents were associated with increased risk of CaOx urolith formation. Diets with the highest magnesium, phosphorus, calcium, chloride, or fiber contents and moderate protein content were associated with increased risk of MAP urolith formation. On the other hand, diets with the highest fat content were associated with decreased risk of MAP urolith formation.

Conclusions and Clinical Relevance—Results suggest that diets formulated to contain higher protein, sodium, potassium, moisture, calcium, phosphorus, and magnesium contents and with decreased urine acidifying potential may minimize formation of CaOx uroliths in cats. Diets formulated to contain higher fat content and lower protein and potassium contents and with increased urine acidifying potential may minimize formation of MAP uroliths. (J Am Vet Med Assoc 2001;219:1228–1237)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To test the hypothesis that breed, age, sex, body condition, and environment are risk factors for development of calcium oxalate uroliths in dogs.

Design—Case-control study.

Animals—1,074 dogs that formed calcium oxalate uroliths and 1,724 control dogs that did not have uroliths.

Procedure—A validated multiple-choice questionnaire was designed to collect information from veterinarians and owners within 1 year of the date of urolith detection concerning signalment and environment of the dogs. Univariate and multivariate analyses were performed to calculate odds ratios to assess whether breed, age, sex, body condition, and environment were risk factors for calcium oxalate urolith formation.

Results—Middle-aged (8- to 12-year-old) castrated male dogs had increased risk for formation of calcium oxalate uroliths. Urolith formation was also associated with increasing age. Dogs of certain breeds, including Miniature and Standard Schnauzer, Lhasa Apso, Yorkshire Terrier, Bichon Frise, Shih Tzu, and Miniature and Toy Poodle, had increased risk for developing calcium oxalate uroliths. Overweight dogs also had increased risk.

Conclusions and Clinical Relevance—Knowledge of patient and environmental risk factors for development of calcium oxalate uroliths may facilitate development of surveillance strategies that result in earlier detection of this disease. Modification of environmental factors and body weight may minimize calcium oxalate urolith formation and recurrence. (J Am Vet Med Assoc 2000;217:515–519)

Full access
in Journal of the American Veterinary Medical Association

Objective

To test the hypothesis that breed, sex, and age of cats, and anatomic location of uroliths are risk factors for calcium oxalate and magnesium ammonium phosphate urolithiasis.

Design

Retrospective case-control study.

Sample Population

Records of 3,498 feline urolith accessions submitted between September 1982 and September 1992.

Procedure

Mineral composition of feline uroliths was quantitatively analyzed. Odds ratios and 95% confidence intervals were calculated for breed, sex, age, and urolith location as risk factors for calcium oxalate and magnesium ammonium phosphate urolith formation. The population at risk was defined as all cats for which that type of urolith had been submitted. The control population was all cats for which uroliths had been submitted, excluding cats with the type of urolith being evaluated.

Results

Burmese, Persian, and Himalayan breeds were at higher risk for developing calcium oxalate uroliths, but at reduced risk for developing magnesium ammonium phosphate uroliths. Compared with females, neutered male cats had a higher risk for developing calcium oxalate uroliths, but a reduced risk for developing magnesium ammonium phosphate uroliths. The risk for calcium oxalate urolith formation increased with age. One- to 2-year-old female cats had the highest risk for magnesium ammonium phosphate uroliths. Uroliths removed from the kidneys were more likely to be composed of calcium oxalate than of magnesium ammonium phosphate.

Clinical Implications

Breed, sex, and age of cats, and anatomic location of uroliths should be considered when evaluating risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in urolith-forming cats. (J Am Vet Med Assoc 1996; 208:547–551)

Free access
in Journal of the American Veterinary Medical Association