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- Author or Editor: Dennis J. Chew x
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Objective—To determine whether total serum calcium (tCa) or adjusted tCa concentrations accurately predict ionized calcium (iCa) status in dogs.
Sample Population—1,633 canine serum samples.
Procedure—The tCa concentration was adjusted for total protein (TP) or albumin concentration by use of published equations. Correlations between iCa and tCa or adjusted tCa, tCa and TP, and tCa and albumin were calculated. Diagnostic discordance between tCa or adjusted tCa and iCa was determined. Diagnostic discordance in predicting iCa was also determined for 490 dogs with chronic renal failure (CRF). Sensitivity, specificity, positive and negative predictive values, and positive and negative diagnostic likelihood ratios were calculated for tCa, tCa adjusted for TP, and tCa adjusted for albumin.
Results—Diagnostic discordance was 27% when tCa concentration was used to predict iCa status. Use of adjusted tCa increased diagnostic discordance to approximately 37% for all dogs and 55% for dogs with CRF. Positive predictive value and positive diagnostic likelihood ratios were poor when tCa concentration was used to predict iCa status. The tCa concentration overestimated normocalcemia and underestimated hypocalcemia. Adjusted tCa overestimated hypercalcemia and underestimated hypocalcemia.
Conclusions and Clinical Relevance—Adjusted tCa or tCa concentrations are unacceptable for predicting iCa status in dogs. Use of adjustment equations is not recommended. Direct measurement of iCa concentration is necessary for accurate assessment of calcium status. Use of tCa or adjusted tCa concentrations to predict iCa status in dogs could cause serious mistakes in diagnosis and case management, especially in dogs with CRF. (Am J Vet Res 2005;66:1330–1336)
Objective—To determine concentrations of calcium (total [tCa], ionized [iCa], protein-bound [pCa], and complexed [cCa]) in dogs with chronic renal failure (CRF).
Animals—23 dogs with CRF.
Procedure—Serum calcium was fractionated by use of a micropartition system. Total calcium and iCa concentrations and pH were measured in unfractionated serum, and tCa concentration was measured in the ultrafiltrate. The pCa fraction was calculated by subtracting tCa of the ultrafiltrate from tCa concentration of unfractionated serum. The iCa concentration in unfractionated serum was subtracted from tCa concentration in the ultrafiltrate to determine the concentration of cCa.
Results—Concentrations of tCa, iCa, pCa, and cCa had wide ranges among dogs with CRF. Dogs with significantly low tCa concentration (7.70 ± 1.73 mg/dL) had cCa concentration (0.76 ± 0.38 mg/dL) within reference range, whereas dogs with reference range to high tCa concentration (10.85 ± 1.13 mg/dL) had significantly high cCa concentration (2.62 ± 1.04 mg/dL). There was no significant difference in iCa or pCa concentrations between groups.
Conclusions and Clinical Relevance—Concentrations of tCa, iCa, cCa, and pCa varied widely in dogs with CRF. Overall, cCa concentration was high, although subpopulations differed in cCa and tCa concentrations. Differences in tCa concentration were primarily attributable to differences in cCa fraction. (Am J Vet Res 2003;64:1181–1184)
Objective—To determine the effect of number of blood samples and sampling times on plasma clearance of technetium Tc 99m pentetate (Tc99mP) and orthoiodohippurate sodium I 131(OIH).
Animals—20 dogs and 14 cats.
Procedure—Plasma clearances of OIH and Tc99mP were calculated by use of a 2-compartment model, on the basis of a 12-point curve as a reference method. Plasma clearance was calculated by use of all possible combinations of 4 to 11 samples. Time schedule yielding the smallest difference from the reference method was considered to be optimal. Regression analysis was performed between the 12-point model and models using a reduced number of samples.
Results—SD of the difference between the 12-point clearance and the models with reduced numbers of samples increased when the number of samples decreased. The SD of the difference between 12-point clearance and 4-point clearance was 4.17 ml/min for OIH and 0.94 ml/min for Tc99mP in dogs and 0.45 ml/min for OIH and 0.11 ml/min for Tc99mP in cats. Optimal schedules were distributed logarithmically and included an early sample at 5 or 10 minutes, a late sample at 2.5, 3, 4, or 5 hours for OIH, and a late sample at 4 or 5 hours for Tc99mP.
Conclusions and Clinical Relevance—Plasma clearances of OIH and Tc99mP can be accurately calculated in dogs and cats by use of a single-injection 2-compartment pharmacologic model with a reduced number of blood samples, resulting in an acceptable margin of error. (Am J Vet Res 2000;61:280–285)
Objective—To determine efficacy of a protocol for managing urethral obstruction (UO) in male cats without urethral catheterization.
Animals—15 male cats with UO in which conventional treatment had been declined.
Procedures—Laboratory testing and abdominal radiography were performed, and cats with severe metabolic derangements or urinary calculi were excluded. Treatment included administration of acepromazine (0.25 mg, IM, or 2.5 mg, PO, q 8 h), buprenorphine (0.075 mg, PO, q 8 h), and medetomidine (0.1 mg, IM, q 24 h) and decompressive cystocentesis and SC administration of fluids as needed. Cats were placed in a quiet, dark environment to minimize stress. Treatment success was defined as spontaneous urination within 72 hours and subsequent discharge from the hospital.
Results—Treatment was successful in 11 of the 15 cats. In the remaining 4 cats, treatment was considered to have failed because of development of uroabdomen (n = 3) or hemoabdomen (1). Cats in which treatment failed had significantly higher serum creatinine concentrations than did cats in which treatment was successful. Necropsy was performed on 3 cats in which treatment had failed. All 3 had severe inflammatory disease of the urinary bladder, but none had evidence of bladder rupture.
Conclusions and Clinical Relevance—Results suggested that in male cats, a combination of pharmacological treatment, decompressive cystocentesis, and a low-stress environment may allow for resolution of UO without the need for urethral catheterization. This low-cost protocol could serve as an alternative to euthanasia when financial constraints prevent more extensive treatment.
Objective—To clone and sequence the cDNA for feline preproparathyroid hormone (preproPTH) and to compare that sequence with other known parathyroid hormone (PTH) sequences.
Sample Population—Parathyroid glands from 1 healthy cat.
Procedure—A cDNA library was constructed in λ phage from feline parathyroid gland mRNA and screened with a radiolabeled canine PTH probe. Positive clones were sequenced, and nucleic acid and deduced amino acid sequences were analyzed and compared with known preproPTH and PTH sequences.
Result—Screening of approximately 2 X 105 recombinant plaques revealed 3 that hybridized with the canine PTH probe; 2 clones comprised the complete sequence for feline preproPTH. Feline preproPTH cDNA consisted of a 63-base pair (bp) 5'-untranslated region (UTR), a 348-bp coding region, and a 326-bp 3'-UTR. The coding region encoded a 115-amino acid peptide. Mature feline PTH consisted of 84 amino acids. Amino acid sequence analysis revealed that feline PTH was > 83% identical to canine, bovine, swine, equine, human, and macaque PTH and 69, 71, and 44% identical to mouse, rat, and chicken PTH, respectively. Within the region responsible for hormonal activity (amino acids 1 to 34), feline PTH was > 79% identical to other mammalian PTH sequences and 64% identical to the chicken sequence.
Conclusions and Clinical Relevance—The amino acid sequence of PTH is conserved among mammalian species. Knowledge of the cDNA sequence for feline PTH may be useful to investigate disturbances of calcium metabolism and alterations in PTH expression in cats. (Am J Vet Res 2002;63:194–197)
Objective—To evaluate calcium balance and parathyroid gland function in healthy horses and horses with enterocolitis and compare results of an immunochemiluminometric assay (ICMA) with those of an immunoradiometric assay (IRMA) for determination of serum intact parathyroid hormone (PTH) concentrations in horses.
Animals—64 horses with enterocolitis and 62 healthy horses.
Procedures—Blood and urine samples were collected for determination of serum total calcium, ionized calcium (Ca2+) and magnesium (Mg2+), phosphorus, BUN, total protein, creatinine, albumin, and PTH concentrations, venous blood gases, and fractional urinary clearance of calcium (FCa) and phosphorus (FP). Serum concentrations of PTH were measured in 40 horses by use of both the IRMA and ICMA.
Results—Most (48/64; 75%) horses with enterocolitis had decreased serum total calcium, Ca2+, and Mg2+ concentrations and increased phosphorus concentrations, compared with healthy horses. Serum PTH concentration was increased in most (36/51; 70.6%) horses with hypocalcemia. In addition, FCa was significantly decreased and FP significantly increased in horses with enterocolitis, compared with healthy horses. Results of ICMA were in agreement with results of IRMA.
Conclusions and Clinical Relevance—Enterocolitis in horses is often associated with hypocalcemia; 79.7% of affected horses had ionized hypocalcemia. Because FCa was low, it is unlikely that renal calcium loss was the cause of hypocalcemia. Serum PTH concentrations varied in horses with enterocolitis and concomitant hypocalcemia. However, we believe low PTH concentration in some hypocalcemic horses may be the result of impaired parathyroid gland function. ( Am J Vet Res 2001;62:938–947)
Objective—To evaluate transurethral cystoscopy and excretory urography for diagnosis of ectopic ureter in female dogs and identify concurrent urogenital abnormalities.
Animals—25 female dogs.
Procedure—Medical records of female dogs that underwent transurethral cystoscopy, excretory urography, and ventral cystotomy were reviewed for signalment, history, physical examination findings, results of bacteriologic culture of urine, and surgical findings. Videotapes of transurethral cystoscopy and radiographic studies were reviewed systematically without knowledge of surgical findings.
Results—Ectopic ureters were diagnosed in 24 of 25 (96%) of the dogs, bilaterally in 22 of 24 (91.6%) dogs. Cystoscopic evaluation yielded a correct diagnosis in all dogs when results of ventral cystotomy were used as the diagnostic standard. Cystoscopic evaluation identified a terminal ureteral opening for all ureters. Urethral fenestrations, troughs, striping, and tenting were identified. Abnormalities of the vestibule were identified in all examinations available for review (24/25). The paramesonephric septal remnant and its association with ectopic ureters were identified and characterized by cystoscopy. Radiographic findings were discordant with surgical findings and correctly identified 36 of 46 (78.2%) ectopic ureters and 2 of 4 normal ureters. Hydroureter and renal abnormalities were associated with distal urethral ectopic ureters on radiographic evaluations.
Conclusions and Clinical Relevance—Transurethral cystoscopy was accurate and minimally invasive for identification and classification of ectopic ureters in dogs. Contrast radiography had limitations in diagnosis of ectopic ureters. Cystoscopic findings and associated vaginal and vestibular abnormalities support abnormal embryologic development in the pathogenesis of ectopic ureters. (J Am Vet Med Assoc 2003;223:475–481)
Case Description—A 6-month-old female domestic shorthair cat was admitted for evaluation of intermittent clinical signs of hematuria and inappropriate urination for the past 2 months.
Clinical Findings—Transabdominal ultrasonography revealed a multilayered mass in the urinary bladder apex consistent with full-thickness invagination of the bladder wall.
Treatment and Outcome—Exploratory surgery was performed, and partial inversion of the urinary bladder was confirmed. The invaginated bladder apex was manually reduced, and partial cystectomy was performed to remove the invaginated section of bladder wall. Histologic findings were consistent with vascular congestion and edema secondary to partial invagination. Bacterial culture of a section of the bladder mucosa demonstrated concurrent bacterial urinary tract infection. Clinical signs resolved following surgical resection of the bladder apex and antimicrobial treatment for the concurrent urinary tract infection.
Clinical Relevance—Partial invagination of the urinary bladder should be considered in the differential diagnosis for cats with clinical signs of hematuria, stranguria, and inappropriate urination. A diagnosis may be made on the basis of detection of invaginated tissue in the bladder apex during abdominal ultrasonography.