ESTIMATION OF FELINE RENAL VOLUME USING COMPUTED TOMOGRAPHY AND ULTRASOUND

Renal volume estimation is an important parameter for clinical evaluation of kidneys and research applications. A time efficient, repeatable, and accurate method for volume estimation is required. The purpose of this study was to describe the accuracy of ultrasound and computed tomography (CT) for estimating feline renal volume. Standardized ultrasound and CT scans were acquired for kidneys of 12 cadaver cats, in situ. Ultrasound and CT multiplanar reconstructions were used to record renal length measurements that were then used to calculate volume using the prolate ellipsoid formula for volume estimation. In addition, CT studies were reconstructed at 1 mm, 5 mm, and 1 cm, and transferred to a workstation where the renal volume was calculated using the voxel count method (hand drawn regions of interest). The reference standard kidney volume was then determined ex vivo using water displacement with the Archimedes’ principle. Ultrasound measurement of renal length accounted for approximately 87% of the variability in renal volume for the study population. The prolate ellipsoid formula exhibited proportional bias and underestimated renal volume by a median of 18.9%. Computed tomography volume estimates using the voxel count method with hand‐traced regions of interest provided the most accurate results, with increasing accuracy for smaller voxel sizes in grossly normal kidneys (–10.1 to 0.6%). Findings from this study supported the use of CT and the voxel count method for estimating feline renal volume in future clinical and research studies.     

Understanding the effect of repeated administration of meloxicam on feline renal cortex and medulla: A lipidomics and metabolomics approach

Repeated administration of meloxicam can cause kidney damage in cats by mechanisms that remain unclear. Metabolomics and lipidomics are powerful, noninvasive approaches used to investigate tissue response to drug exposure. Thus, the objective of this study was to assess the effects of meloxicam on the feline kidney using untargeted metabolomics and lipidomics approaches. Female young‐adult purpose‐breed cats were allocated into the control (n = 4) and meloxicam (n = 4) groups. Cats in the control and meloxicam groups were treated daily with saline and meloxicam at 0.3 mg/kg subcutaneously for 17 days, respectively. Renal cortices and medullas were collected at the end of the treatment period. Random forest and metabolic pathway analyses were used to identify metabolites that discriminate meloxicam‐treated from saline‐treated cats and to identify disturbed metabolic pathways in renal tissue. Our results revealed that the repeated administration of meloxicam to cats altered the kidney metabolome and lipidome and suggest that at least 40 metabolic pathways were altered in the renal cortex and medulla. These metabolic pathways included lipid, amino acid, carbohydrate, nucleotide and energy metabolisms, and metabolism of cofactors and vitamins. This is the first study using a pharmacometabonomics approach for studying the molecular effects of meloxicam on feline kidneys.     

VALIDATION OF A NOVEL TRANSLUMBAR ULTRASOUND TECHNIQUE FOR MEASURING RENAL DIMENSIONS IN HORSES

A reliable method for obtaining renal ultrasonographic measurements in the horse is important for diagnosis and monitoring of clinical renal disease. The aims of this prospective study were to develop and validate a novel translumbar ultrasound technique for measuring renal dimensions in horses. Six Thoroughbred or Thoroughbred part bred horses were recruited. All horses were scheduled for euthanasia due to reasons unrelated to the kidneys. Two observers recorded renal length, width, and depth; and dimensions of the cortex, medulla, pyramids, and pelvis for both kidneys in each horse using novel translumbar and conventional transabdominal ultrasound methods. The same measurements were recorded from post‐mortem renal specimens. Both kidneys were consistently identified by both methods in the 15–17th intercostal spaces and paralumbar fossa. Using the translumbar technique, maximal dimensions were obtained for the left kidney in the 16th intercostal space (length 16.2 ± 2.0 cm, width 11.8 ± 0.5 cm, depth 6.4 ± 0.9 cm) and for the right kidney in the 15th intercostal space (length 16.1 ± 1.2 cm, width 13.4 ± 1.2 cm, depth 6.7 ± 0.7 cm). Renal dimensions obtained by transabdominal and translumbar projections did not differ (P > 0.05). Good correlations were found between overall renal dimensions and post‐mortem measurements for both ultrasound techniques (r² > 0.8), but were better for the translumbar method (mean r² = 0.92 cf. 0.88). Good‐to‐excellent reliability was found for all translumbar ultrasound measurements except for the renal cortex. Reproducibility was better for the larger (overall length, width, and depth) than the smaller (cortex, medulla, and pyramids) structures. Findings indicated that translumbar ultrasonography is a valid method for measuring renal dimensions in horses.     

EFFECT OF REPRODUCTIVE STATUS ON FELINE RENAL SIZE

Renal length and width dimensions were determined from survey radiography and excretory urography in 28 cats of various sex and reproductive status. Renal dimensions were expressed as a ratio to the length of the second lumbar vertebra. Renal dimensions were not significantly different when males were compared to females. However, significant differences in renal dimensions between intact and neutered cats were identified. Renal length ratios for neutered cats were: left kidney 2.22 +/- 0.14 (mean +/- standard deviation), right kidney 2.29 +/- 0.14. In intact cats, renal length ratios were: left kidney 2.60 +/- 0.19, right kidney 2.65 +/- 0.24. The mean renal length ratios for neutered cats was smaller than previously reported normal values. Thus, reproductive status should be considered when evaluating feline kidneys for alterations in size. Based on this study, normal feline renal length ratios range from 1.9 to 2.6 for neutered cats and 2.1 to 3.2 for intact cats.     

CONTRAST‐ENHANCED ULTRASOUND OF THE FELINE KIDNEY

Contrast‐enhanced ultrasound offers a noninvasive means of subjectively and quantitatively evaluating renal perfusion in cats with renal disease, or in renal transplant patients. In this study, we characterized the pattern of ultrasonographic contrast enhancement in 16 normal feline kidneys in eight cats using contrast‐enhanced power Doppler and contrast‐enhanced harmonic ultrasound techniques. Mean time to peak contrast enhancement for the whole kidney was longer using contrast‐enhanced harmonic ultrasound (16.8s, SD 4.7s) than contrast‐enhanced power Doppler ultrasound (12.2s, SD 1.8s). The time to peak enhancement for the cortex alone in contrast‐enhanced harmonic ultrasound was 13s (SD 3.2s), and for the renal medulla was 25.5s (SD 8.7s). The half time for washout of contrast agent was 39s (SD 14.5s) for contrast‐enhanced harmonic ultrasound. The pattern of contrast enhancement in these normal feline kidneys can be used as normal reference values for the evaluation of clinical patients. Contrast‐enhanced harmonic ultrasound may allow the differentiation between cortical and medullary perfusion patterns.     

Use of radiographs and computed tomography for measurement of kidney size in healthy chinchillas (Chinchilla lanigera)

BackgroundChinchillas, being small mammals, are subject to many of the urinary disorders that affect other companion animals. In cats and dogs, relationships between renal length and the presence of renal pathology have been well documented through the use of diagnostic imaging. Radiography and computed tomography (CT) are two commonly utilized diagnostic imaging modalities for assessing renal pathology. Presently, there are no published data on chinchilla kidney size and appearance using radiography or CT. This study aimed to determine healthy adult chinchilla renal size and correlate renal size to L2 body length and aortic diameter by use of radiography and CT.MethodsTwenty-eight healthy adult chinchillas with no clinical evidence of renal disease were placed under sedation for acquisition of radiographs and CT imaging. Both kidneys were measured on the radiographic views (right lateral, left lateral and ventrodorsal), when identifiable. Renal length, L2 body length and abdominal aortic diameter were measured on CT multiplanar reformatted images in specified planes and windows.ResultsIn 25% (7/28) of chinchillas, the renal length of either kidney could not be obtained on any of the three radiographic views due to superimposition of fluid and ingesta within the alimentary tract. Both the right and left kidney were identified on CT images in 100% of chinchillas (28/28). The left renal and right renal 95% confidence intervals from the dorsal plane CT images were 2.26 – 2.33 cm and 2.31 – 2.39 cm, respectively. No correlation was found between kidney length, L2 body length and diameter of the abdominal aorta on CT images.ConclusionsBased on dorsal plane CT imaging, normal chinchilla renal length is proposed to be between 2.25–2.4 cm.Clinical RelevanceRadiographic evaluation of chinchilla renal length is greatly limited due to their large fluid- and ingesta-filled colon and cecum, as is typical of animals that are hindgut fermenters. Through establishment of a normal CT reference interval for renal length and the ever-increasing clinical utility of CT, clinicians can better evaluate chinchilla renal length and identify alterations that may indicate pathologic processes.     

Comparison of the Morphometric Features of the Left and Right Horse Kidneys: A Stereological Approach

The aims of this study were to determine the total volume of the horse kidney and volume fractions of its functional subcomponents (cortex, medulla, renal pelvis) using stereological methods and investigate any possible difference in the functional subcomponents of the right and left kidneys that may arise from differences in shape. The study was carried out on the kidneys of 5 horses of different breed and sex. The weight of the kidneys was measured by a digital scale, and kidney volume was calculated by Archimedes' principle. Total kidney volume and volume fractions of subcomponents of the right and left kidneys were estimated by the Cavalieri's principle. The weights of the right and left kidneys were 550 ± 25 g and 585 ± 23 g, respectively. The volumes of the right and left kidneys estimated using the Cavalieri method were 542 ± 46 ml and 581 ± 29 ml. The relative organ weight of the kidneys was calculated as 1:330. The densities of the right and left kidneys were determined to be 1.01 and 1.00, respectively. The mean volume fractions of the cortex, medulla and renal pelvis were determined as 55.6, 42.7 and 1.7 in both kidneys. No statistically significant difference existed between morphometric data pertaining to the right and left kidneys (P > 0.05). To determine precisely whether differences in shape cause any difference in the functional subcomponents of the right and left kidneys requires further investigation of differences in the number of microscopically functional unit of the kidney such as renal glomeruli and nephrons.     

Feline pancreatic ducts are consistently identified on CT and more likely to be dilated in the body of pancreas in cats with elevated feline pancreatic lipase immunoreactivity

Feline pancreatitis is a challenge to diagnose and no previously published study has described the CT characteristics of the pancreatic duct (PD) in cats. The current prospective analytical study was performed to identify and describe the CT characteristics of the PD in normal cats and to compare that to those cats with an elevated feline pancreatic lipase immunoreactivity (fPLI). Contrast‐enhanced CT was performed in 16 normal cats and 13 cats with an elevated fPLI. Two ACVR‐certified radiologists blinded to the fPLI status assessed whether or not the PD could be identified, contrast phase during which the PD was most conspicuous, and PD shape in the body, right and left lobes. A second‐year radiology resident blinded to the fPLI status measured maximum PD diameter and PD:parenchyma. The PD was identified in 84 of 87 pancreatic segments, which was most conspicuous in the portal phase in 28 of 29 cats. The PD shape was tubular (48/84), tapered (34/84), or beaded (2/84) with no significant difference (P = 1.0 to .1615) between groups. Mean maximal PD diameters of normal cats were 1.5‐1.7 mm, which was significantly larger in the body of the pancreas in cats with an elevated fPLI (2.4 mm, P = .0313). Mean PD:parenchyma was not significantly different between groups (P = .2001 to .949). In conclusion, the feline PD can be consistently identified on CT, for which the portal phase is preferred. Cats with an elevated fPLI are more likely to exhibit dilation of the PD in the body of the pancreas on CT.     

Corneal innervation in mesocephalic and brachycephalic dogs and cats: assessment using in vivo confocal microscopy

Objective To determine the density of the canine and feline corneal neural network in healthy dogs and cats using in vivo confocal microscopy (IVCM). Animals examined A total of 16 adult dogs (9 Mesocephalic breeds, 7 Brachycephalic breeds) and 15 cats (9 Domestic Short-haired cats (DSH), 6 Persian cats) underwent IVCM. Procedure Animals were examined with a confocal corneal microscope (HRTII/RCM; Heidelberg Retina Tomograph II/Rostock Cornea Module^®, Heidelberg Engineering, Dossenheim, Germany). The investigations focused on the distribution of the corneal nerves and quantification of central subepithelial and subbasal nerve plexus. Results The corneal stromal nerve trunks, subepithelial and subbasal nerve plexus were observed. The nerve fiber density (NFD) quantified in nerve fiber length in mesocephalic dogs were 12.39 ± 5.25 mm/mm² in the subepithelial nerve plexus and 14.87 ± 3.08 mm/mm² in the subbasal nerve plexus. The NFD of the subepithelial nerve plexus in DSH cats was 15.49 ± 2.7 and 18.4 ± 3.84 mm/mm² in the subbasal nerve plexus. The subbasal NFD of DSH cats was significantly higher than in mesocephalic dogs (P = 0.037). The subepithelial NFD in brachycephalic dogs, and Persian cats were 10.34 ± 4.71 and 9.50 ± 2.3 mm/mm², respectively. The subbasal NFD measured 11.80 ± 3.73 mm/mm² in brachycephalic dogs, and 12.28 ± 4.3 mm/mm² NFD in Persian cats, respectively. The subepithelial and subbasal NFD in Persian cats were significantly lower than in DSH cats (P = 0.028, respectively, P = 0.031), in contrast to brachycephalic vs. mesocephalic dogs. Conclusion The noninvasive IVCM accurately detects corneal innervation and provides a reliable quantification of central corneal nerves.     

Felinine excretion in domestic cat breeds: a preliminary investigation

The aim of this study was to determine possible differences in felinine excretion between domesticated cat breeds. For this purpose, urine was collected from a total of 83 privately owned entire male cats from eight different breeds in the Netherlands during the period of November 2010 till November 2011. In the collected samples, free felinine and creatinine concentrations were measured. Free felinine concentrations were expressed relative to the urinary creatinine concentration to compensate for possible variations in renal output. The mean (±SD) felinine:creatinine (Fel:Cr) ratio as measured over all cats was 0.702 (±0.265). Both the Abyssinian and Sphynx breeds showed the highest Fel:Cr ratio (0.878 ± 0.162 and 0.878 ± 0.341 respectively) which significantly differed from the ratios of the British Shorthairs (0.584 ± 0.220), Birmans (0.614 ± 0.266), Norwegian Forest cats (0.566 ± 0.296) and Siberian cats (0.627 ± 0.124). The Fel:Cr ratios of the Persians (0.792 ± 0.284) and Ragdolls (0.673 ± 0.256) showed no statistical difference with either of the other breeds. A significant proportion of the observed variation between the different feline breeds could be explained by hair growth, as both hair growth and felinine production compete for available cysteine. Shorthaired and hairless cat breeds generally showed a higher Fel:Cr ratio compared to longhaired cat breeds, with the exception of Persian cats. Further research is warranted to more closely study the effect of hair growth on felinine production.     

Gene delivery to renal tubular epithelial cells using adeno-associated virus vector in domestic cats

Recombinant adeno-associated virus (rAAV) vectors provide excellent gene delivery into the kidney in several mammals. This study evaluated gene delivery into the cat kidney using an rAAV vector. First, infection and reporter gene expression using rAAV vector encoding the enhanced green fluorescent protein gene (rAAV-EGFP) was examined in vitro in epithelial crandell reese feline kidney (CRFK) cells. At 12 h after transduction, green fluorescence was detected in cells. Next, the rAAV-EGFP construct was injected into the kidneys of two anesthetized cats via the skin, similar to a renal biopsy. On 3 and 12 days after injection, green fluorescence was detected in renal tubules localized near the injected site, but not in glomeruli, blood vessels, or interstitial cells. Finally, the rAAV-EGFP construct was transduced into kidney sections cultured ex vivo. EGFP was expressed in renal tubules between the outer cortex and inner medulla regions. These results demonstrate that rAAV vectors effectively mediate gene delivery into cat renal tubules, and may prove usefulness in gene therapy for cats with renal diseases.     

CONTRAST VIDEOFLUOROSCOPIC ASSESSMENT OF DYSPHAGIC CATS

The diagnostic utility of contrast‐enhanced videofluoroscopic esophagography in dysphagic cats has been rarely studied relative to dogs. Current literature regarding feline dysphagia typically consists of individual case reports or small case series. This retrospective study analyzed the imaging findings in 11 cats undergoing 15 videofluoroscopic swallow studies. Hiatal hernia (n = 5), esophageal stricture (n = 3), and esophageal dysmotility (n = 7) were the most common diagnoses (some cats having more than 1 diagnosis) in dysphagic cats that underwent videofluoroscopic swallow studies. Esophageal dysmotility appeared to be associated with a higher percentage of swallows from which no peristaltic waves were generated. Oropharyngeal and cricopharyngeal causes of dysphagia were not identified in any cat and quantitative assessment of the swallowing reflex (pharyngeal constriction ratio = 0.17 ± 0.09; time to maximum pharyngeal contraction = 0.13 ± 0.02 s; time to proximal esophageal sphincter opening = 0.07 ± 0.02 s; time to proximal esophageal sphincter closed = 0.23 ± 0.05 s; time to opening of the epiglottis = 0.27 ± 0.04 s) was similar to quantitative swallowing parameters previously reported in healthy dogs. In conclusion, videofluoroscopy is a diagnostic tool that can identify esophageal abnormalities that are not readily apparent on survey radiographs. Limitations include the potential need for multiple studies, and the possibility of poor compliance in the feline patient. Results of this study are intended to help veterinarians define a prioritized differential diagnosis list for dysphagic cats.     

Effects of Dietary Salt Intake on Renal Function: A 2‐Year Study in Healthy Aged Cats

Background

Increasing salt intake to promote diuresis has been suggested in the management of feline lower urinary tract disease. However, high dietary salt intake might adversely affect blood pressure and renal function.

Objectives

The objective of this study was to assess the long‐term effects of increased salt intake on renal function in healthy aged cats.

Methods

This study was controlled, randomized, and blinded. Twenty healthy neutered cats (10.1 ± 2.4 years) were randomly allocated into 2 matched groups. One group was fed a high salt diet (3.1 g/Mcal sodium, 5.5 g/Mcal chloride) and the other a control diet of same composition except for salt content (1.0 g/Mcal sodium, 2.2 g/Mcal chloride). Clinical examination, glomerular filtration rate, blood pressure measurement, cardiac and kidney ultrasonography, and urinary and blood tests were performed before and over 24 months after diet implementation. Statistics were performed using a general linear model.

Results

Sixteen cats completed the 2 year study. The only variables affected by dietary salt intake were plasma aldosterone and urinary sodium/creatinine ratio, respectively, higher and lower in the control group all over the study period and urinary specific gravity, lower in the high salt diet group at 3 months.

Conclusions and Clinical Importance

Glomerular filtration rate (GFR), blood pressure, and other routine clinical pathological variables in healthy aged cats were not affected by dietary salt content. The results of this 2 year study do not support the suggestion that chronic increases in dietary salt intake are harmful to renal function in older cats.     

Ocular surface physiology and aqueous tear secretion in cats of diverse cephalic conformations

Objective

To describe normative ocular surface and aqueous tear testing data for cats of various cephalic conformation.

Animals studied

Fifty-three healthy adult cats (11 British Shorthair, 11 Burmese, 10 Devon Rex, 10 Scottish Fold, and 11 Sphynx).

Procedures

Blink rate, corneal tactile sensation (CTS), and Schirmer tear test with or without topical anesthesia (STT-1, STT-2) and with nasolacrimal stimulation (NL-STT1, NL-STT2) were assessed. Palpebral fissure length (PFL) and skull morphology were measured, and cephalic index (CI) and craniofacial ratio (CFR) calculated.

Results

Mean ± SD test results were as follows: blink rate (5.0 ± 2.3 blinks/min), CTS (3.2 ± 0.7 cm), STT-1 (11.2 ± 4.3 mm/min), STT-2 (6.7 ± 3.6 mm/min), NL-STT1 (13.4 ± 5.7 mm/min), NL-STT2 (13.5 ± 5.2 mm/min), and PFL (2.0 ± 0.2 cm). Corneal sensitivity did not differ significantly among breeds (p = .152) but was negatively correlated with body weight (r = −.32, p = .019). STT-1 significantly differed among breeds (p < .001) and was lowest in Sphynx cats (8.7 ± 4.3 mm/min). A positive correlation was detected between STT-1 values at 30 and 60 s (r = .98; p < .001). The nasolacrimal reflex significantly increased STT in anesthetized and unanesthetized eyes (approximately +100% and +20%, respectively; p ≤ .002). STT-1 tended to be higher in intact versus neutered cats (p = .062). Age did not impact any test result (p ≥ .085).

Conclusions

Normative data described here serve as a baseline for future studies assessing ocular surface disease in multiple feline breeds. Unlike dogs, brachycephalic cats did not have lower CTS or STT-1 than non-brachycephalic cats.     

Mensuration of the rabbit pituitary gland from computed tomography

The aim of this retrospective reference interval observational study was to determine the mensuration of the pituitary gland (hypophysis cerebri) by analyzing CT studies in rabbits without clinical evidence of pituitary disease or central neurologic signs. Though diseases of the rabbit pituitary gland are uncommon, the pituitary gland is essential in regulation of the rabbit's endocrine system, as in other species. Currently, there are minimal published studies that detail the rabbit head anatomy on cross‐sectional imaging, and even less specifically examining the pituitary gland. The pituitary gland was measured by one observer at a single time point from transverse and reconstructed sagittal CT images in a soft‐tissue algorithm in 62 rabbits for a total of 66 rabbit head CT studies. The rabbits ranged from 0.84 to 14 years in age (mean ± SD: 5.46 ± 3.05 years) and 0.92 to 4.95 kg in weight (2.21 ± 0.83 kg). Linear pituitary measurements were performed using electronic calipers. The mean ± SD pituitary height was 4.22 ± 0.57 mm, width was 4.48 ± 0.71 mm, and length was 6.02 ± 0.70 mm. The pituitary gland height‐to‐brain area ratio was 1.10 ± 0.16 mm^?1, which is much higher than the values reported in normal dogs and cats. The age, weight, and sex of the rabbits were not found to have a significant impact on pituitary gland mensuration. These measurements could be useful as a reference range for future rabbit head CT studies and to rule out pituitary enlargement or disease when evaluating rabbit pituitary glands.     

MULTIDETECTOR‐ROW COMPUTED TOMOGRAPHIC CHARACTERISTICS OF PRESUMED PREURETERAL VENA CAVA IN CATS

Preureteral vena cava (circumcaval ureter, retrocaval ureter) occurs in a third of the feline population and has been associated with ureteral strictures in humans. The aim of this retrospective cross‐sectional study was to describe the contrast‐enhanced multidetector row computed tomographic (MDCT) characteristics of presumed preureteral vena cava in a group of cats. Medical records from two institutions located in different continents were searched from 2010–2013 for cases with complete contrast‐enhanced MDCT examinations of the abdomen (i.e. included the entire course of the ureters and prerenal and renal segments of the caudal vena cava) and a diagnosis of preureteral caudal vena cava. For cases meeting inclusion criteria, CT scan data were retrieved and characteristics of the preureteral caudal vena cava were recorded. Presence of concomitant renal or ureteral diseases was also recorded. A total of 272 cats had contrast‐enhanced abdominal CT scans during the study period and of these, 68 cats (22.43 ± 4.96%) had a diagnosis of presumed preureteral vena cava. In all affected cats, a “reverse‐J ureter” was observed, i.e. a ureter running medially at the level of L4–5, passing dorsally to the caudal vena cava and then exiting ventrally between the caudal vena cava and aorta returning to its normal position. Having a preureteral vena cava resulted in an increased risk for concurrent urinary signs (OR = 3.00; CI: 95%; 1.28–6.99; P = 0.01). Findings supported the use of contrast‐enhanced MDCT for characterizing morphology of preureteral vena cava and its relation with ureters in cats.     

Prevalence of the polycystic kidney disease and renal and urinary bladder ultrasonographic abnormalities in Persian and Exotic Shorthair cats in Italy

The ultrasonographic findings of kidneys, liver and urinary bladder of 288 Persian and 44 Exotic Shorthair clinically normal cats that underwent screening for polycystic kidney disease (PKD) between July 2003 and December 2005 were reviewed. Cats were divided into two groups, one including cats aged <9 months (group 1) and one cats aged >/=9 months (group 2). Cats were classified as PKD-positive when at least one renal cyst was found. One hundred and thirty-six cats (41.0%) had more than one cyst in at least one kidney. The prevalence of PKD was similar in both groups. Eight PKD-positive cats had cystic livers (5.9%). Other renal abnormalities included a pelvic calculus and a medullary rim sign (MRS). The difference in prevalence of an MRS in group 2 compared to group 1 and the difference between PKD-positive and -negative cats in group 2 were not significant. There was no difference in mean kidney length between PKD-positive and -negative cats in group 2. Urinary bladder anomalies were principally represented by urinary sediment, with prevalence significantly higher in group 2. No difference was detected in group 2 between PKD-positive and -negative cats. In conclusion feline PKD is common in Italy. The ultrasonographic findings of MRS and urinary bladder sediment did not correlate with feline PKD. Urinary bladder sediment is common in Persians and Exotic Shorthairs and more likely in adults.     

Feline platelet counting with prostaglandin E1 on the Sysmex XT‐2000iV

Background: The large size of many feline platelets and the high frequency of platelet aggregation often results in falsely low platelet counts in this species. A combination of optical platelet counting to detect even large platelets and the use of prostaglandin E1 (PGE1) to inhibit platelet clumping may increase the accuracy of feline platelet counting. Objective: The objective of this study was to compare platelet counts in feline whole blood samples with and without the addition of PGE1 and using different analytical methods in a clinical setting. Methods: Platelet counts were determined in 10 feline patients in a referral veterinary hospital using 2 sample types (EDTA, EDTA with PGE1) and 2 methods of analysis (optical counting [PLT‐O] and impedance counting [PLT‐I]) on the Sysmex XT 2000 iV analyzer. Results: All PGE1–PLT‐O samples had platelet counts of >200 × 10⁹/L. Mean platelet count using PGE1–PLT‐O (410,256±178 × 10⁹/L) was significantly higher (P<.03) compared with PGE1–PLT‐I (256±113 × 10⁹/L), EDTA–PLT‐O (238±107 × 10⁹/L), and EDTA–PLT‐I (142±84 × 10⁹/L) methods. Depending on the method, platelet counts in 2 to 7 of 10 cats were <200 × 10⁹/L when PGE1‐PLT‐O was not used. A slightly increased platelet count in response to treatment of a feline patient with thrombocytopenia would have been missed without use of PGE1–PLT‐O. Conclusions: Using PLT‐O analysis on EDTA samples containing PGE1 provides higher, and therefore likely more accurate, feline platelet counts in a clinical setting.     

Oral,subcutaneous, and intravenous pharmacokinetics of ondansetron in healthy cats

Ondansetron is a 5‐HT₃ receptor antagonist that is an effective anti‐emetic in cats. The purpose of this study was to evaluate the pharmacokinetics of ondansetron in healthy cats. Six cats with normal complete blood count, serum biochemistry, and urinalysis received 2 mg oral (mean 0.43 mg/kg), subcutaneous (mean 0.4 mg/kg), and intravenous (mean 0.4 mg/kg) ondansetron in a cross‐over manner with a 5‐day wash out. Serum was collected prior to, and at 0.25, 0.5, 1, 2, 4, 8, 12, 18, and 24 h after administration of ondansetron. Ondansetron concentrations were measured using liquid chromatography coupled to tandem mass spectrometry. Noncompartmental pharmacokinetic modeling and dose interval modeling were performed. Repeated measures anova was used to compare parameters between administration routes. Bioavailability of ondansetron was 32% (oral) and 75% (subcutaneous). Calculated elimination half‐life of ondansetron was 1.84 ± 0.58 h (intravenous), 1.18 ± 0.27 h (oral) and 3.17 ± 0.53 h (subcutaneous). The calculated elimination half‐life of subcutaneous ondansetron was significantly longer (P < 0.05) than oral or intravenous administration. Subcutaneous administration of ondansetron to healthy cats is more bioavailable and results in a more prolonged exposure than oral administration. This information will aid management of emesis in feline patients.