Dominique Binst

Short- and long-term follow-up of glomerular and tubular renal markers of kidney function in hyperthyroid cats after treatment with radioiodine ☆

Hyperthyroidism can mask co-existing chronic kidney disease (CKD). Previous studies showed that post-treatment renal azotemia can be predicted by pre-treatment assessment of glomerular filtration rate (GFR). We hypothesized that treatment of hyperthyroidism may have different effects on glomerular and tubular function and these changes might be predicted by additional pre-treatment variables than GFR. Serum total T4 (TT4), creatinine and blood urea nitrogen (BUN), blood pressure (BP), body weight (BW), GFR, urine specific gravity (USG), urinary protein/creatinine ratio (UPC) and retinol binding protein/creatinine ratio (uRBP/c) were evaluated before and 1, 4, 12 and 24 weeks post-treatment with radioiodine ((131)I) in 21 non-azotemic hyperthyroid cats. Cats were divided 24 weeks post-treatment into group A (normal kidney function, n=16) and group B (impaired kidney function, n=5). Serum TT4, GFR, UPC and uRBP/c decreased significantly after treatment for the complete group and group A (P<0.05), although GFR and uRBP/c did not change in group B. Serum creatinine and BW increased significantly from 1 week after treatment (P<0.05). There was no change in BUN, USG or BP. Pre-treatment serum TT4, GFR and USG differed significantly between group A and B (P<0.05). GFR at 4 weeks after treatment and maximum decrease in GFR could be partially predicted by a formula using pre-treatment GFR, serum TT4, serum creatinine, BUN and/or USG. Significant changes in kidney function occur within 4 weeks post-treatment and none thereafter. Pre-treatment measurement of GFR, USG and serum TT4 can have possible predictive value regarding the development of post-treatment renal azotemia.

Plasma clearance of exogenous creatinine, exo-iohexol, and endo-iohexol in hyperthyroid cats before and after treatment with radioiodine

BACKGROUND Glomerular filtration rate (GFR) can be measured by clearance methods of different markers showing discrepancies and different reproducibility in healthy cats. Studies comparing different methods of GFR measurement in hyperthyroid cats have not yet been performed. HYPOTHESIS Plasma clearance of exogenous creatinine (PECCT), exo-iohexol (PexICT), and endo-iohexol (PenICT) could lead to differences in GFR measurement and the need to use the same clearance method when comparing GFR before and after radioiodine treatment in hyperthyroid cats. ANIMALS Fifteen client-owned hyperthyroid cats. METHODS GFR was measured 1 day before and 1, 4, 12, and 24 weeks after treatment. Intravenous injection of iohexol was followed immediately by IV injection of creatinine. Plasma creatinine was measured by an enzymatic method. Plasma endo- and exo-iohexol were measured by high-performance liquid chromatography coupled to ultraviolet detection. RESULTS Globally, the 3 GFR methods resulted in significantly different (P < .001) GFR results. GFR results among the different methods were the same (P= .999) at all time points. All 3 techniques indicated decreasing GFR after (131)I treatment. For each GFR technique, a significant decrease in GFR was observed between time point 0 and all other time points. This decrease stabilized 4 weeks after treatment, with very little decline afterward. CONCLUSION AND CLINICAL IMPORTANCE It is mandatory to use the same GFR technique in follow-up studies. GFR testing at 4 weeks posttreatment could allow assessment of the final renal functional loss after treatment in hyperthyroid cats.

Intraobserver and interobserver agreement for results of low-field magnetic resonance imaging in dogs with and without clinical signs of disk-associated wobbler syndrome.

OBJECTIVE To determine interobserver and intraobserver agreement for results of low-field magnetic resonance imaging (MRI) in dogs with and without disk-associated wobbler syndrome (DAWS). DESIGN Validation study. ANIMALS 21 dogs with and 23 dogs without clinical signs of DAWS. PROCEDURES For each dog, MRI of the cervical vertebral column was performed. The MRI studies were presented in a randomized sequence to 4 board-certified radiologists blinded to clinical status. Observers assessed degree of disk degeneration, disk-associated and dorsal compression, alterations in intraspinal signal intensity (ISI), vertebral body abnormalities, and new bone formation and categorized each study as originating from a clinically affected or clinically normal dog. Interobserver agreement was calculated for 44 initial measurements for each observer. Intraobserver agreement was calculated for 11 replicate measurements for each observer. RESULTS There was good interobserver agreement for ratings of disk degeneration and vertebral body abnormalities and moderate interobserver agreement for ratings of disk-associated compression, dorsal compression, alterations in ISI, new bone formation, and suspected clinical status. There was very good intraobserver agreement for ratings of disk degeneration, disk-associated compression, alterations in ISI, vertebral body abnormalities, and suspected clinical status. There was good intraobserver agreement for ratings of dorsal compression and new bone formation. Two of 21 clinically affected dogs were erroneously categorized as clinically normal, and 4 of 23 clinically normal dogs were erroneously categorized as clinically affected. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that variability exists among observers with regard to results of MRI in dogs with DAWS and that MRI could lead to false-positive and false-negative assessments.

Transcranial magnetic stimulation in Doberman Pinschers with clinically relevant and clinically irrelevant spinal cord compression on magnetic resonance imaging

OBJECTIVE To evaluate the use of transcranial magnetic stimulation for differentiating between clinically relevant and clinically irrelevant cervical spinal cord compression on magnetic resonance imaging (MRI). DESIGN Validation study. ANIMALS Clinically normal Doberman Pinschers without (n = 11) and with (6) spinal cord compression on MRI and 16 Doberman Pinschers with disk-associated wobbler syndrome (DAWS). PROCEDURES After dogs were sedated, transcranial magnetic motor evoked potentials were recorded from the extensor carpi radialis muscle (ECRM) and cranial tibial muscle (CTM). Onset latencies and peak-to-peak amplitudes were measured. Magnetic resonance imaging was performed to identify spinal cord compression. RESULTS There were significant differences in ECRM and CTM onset latencies between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM and CTM onset latencies between the 2 groups of clinically normal dogs. There were significant differences in CTM peak-to-peak amplitudes between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM peak-to-peak amplitudes among groups or in CTM peak-to-peak amplitudes between the 2 groups of clinically normal dogs. There was a significant correlation between severity of spinal cord compression and ECRM onset latency, CTM onset latency, and CTM peak-to-peak amplitude. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that transcranial magnetic stimulation may be a useful diagnostic tool to differentiate between clinically relevant and clinically irrelevant spinal cord compression identified on MRI alone.

Long-term follow-up of glomerular and tubular kidney function in hyperthyroid cats after treatment with radioiodine

Adiponectin has been investigated widely due to its association with adiposity and the metabolic syndrome in human beings. Adiponectin circulates as low- (LMW) and high-molecular weight (HMW) multimers and the latter are the more bioactive forms. There are no reports of the relative proportion (distribution) of adiponectin multimers in feline plasma. The aim of this study was to assess the association of dietary nutrient composition, body weight gain, meal feeding, and insulin sensitivity with HMW adiponectin concentration and adiponectin multimer distribution in cats.1 EVALUATION OF FOUR DNA EXTRACTION METHODS FOR THE DETECTION OF TRITRICHOMONAS FOETUS IN FELINE STOOL SPECIMENS BY POLYMERASE CHAIN REACTION. SH Stauffer, AJ Birkenheuer, MG Levy, H Marr, JL Gookin. College of Veterinary Medicine, North Carolina State University, Raleigh, NC. Feces are increasingly recognized as practical samples for molecular diagnosis of infectious disease. Extraction of PCR-quality DNA from feces can be challenging due to co-extraction of PCR inhibitors. Accordingly, we examined the effect of four commercially-available DNA extraction methods on sensitivity of PCR for detection of Tritrichomonas foetus (TF) in naturally-infected and TF-spiked feline stool. Kits evaluated included ExtractMaster Fecal DNA Extraction Kit, Epicentre Biotechnologies (Kit A); QIAamp DNA Stool Mini Kit, Qiagen (Kit B); UltraClean Fecal DNA Kit, MoBio (Kit C); and ZR Fecal DNA Kit, Zymo Research (Kit D). In accordance with manufacturer instructions, DNA was extracted from 180mg (A,B), 50mg (C), 100 & 150mg (D) aliquots of feline feces to which was added 20ml volumes containing 0–10,000 cultured feline TF. Each kit was also used to extract DNA from the feces of each of 10 naturally infected and 10 uninfected cats. DNA was eluted in 300ml (A), 200ml (B), 50ml (C), or 100ml (D) of respective elution buffer. Endogenous PCR inhibitors in extracted DNA was examined by PCR amplification of an 876 bp gene fragment of bacterial 16S rRNA. DNA was then tested by single tube nested PCR for amplification of partial ITS1, 5.8S and ITS2 rRNA genes of TF. Kit D provided the most sensitive detection of TF DNA as expressed by both organisms per DNA extraction and organisms per PCR reaction. To account for differences in DNA concentrations between kits (i.e. fecal sample size and elution volumes), the limit of detection for each kit as expressed by the number of TF per PCR reaction was as follows: Kit B 5 250, Kit A 5 167, Kit C 5 100, Kit D (150mg fecal sample) 5 5, and Kit D (100mg fecal sample) 5 0.5. PCR performed on DNA extracted from cultured TF (no feces) or TF-spiked feces (100mg) using Kit D was positive with as few as 10 TF per extraction. Further, DNA extraction using Kit D could be completed in the shortest time of all kits tested. These studies identify the ZR Fecal DNA Kit as superior to the other kits tested for extraction of PCR-qualityDNA from feline feces. ABSTRACT #2 INVESTIGATION OF ENTEROBACTER CLOACAE INFECTIONS AT A SMALL ANIMAL VETERINARY TEACHING HOSPITAL. JS Weese. University of Guelph, Guelph, Ontario.2 INVESTIGATION OF ENTEROBACTER CLOACAE INFECTIONS AT A SMALL ANIMAL VETERINARY TEACHING HOSPITAL. JS Weese. University of Guelph, Guelph, Ontario. A wide range of pathogens can cause hospital-associated (HA) infections in small animal hospitals. Among these is Enterobacter cloacae, which is one of the most clinically relevant Enterobacter spp and a common cause of HA infection in humans. Recently, multidrug resistance has become a concern, particularly with emergence of extended-spectrum beta-lactamase and extended spectrum cephalosporinase producing strains. An infection control investigation was initiated at the Ontario Veterinary College Teaching Hospital (OVCTH) in the fall of 2007 in response to anecdotal concerns about Enterobacter cloacae infections in hospitalized animals. Enterobacter cloacae was isolated from 45/36719 animals from January 1, 2005 to October 31, 2007, for an overall incidence of 1.2/ 1000 admissions. The monthly incidence rate ranged from 0 to 4.3/ 1000 admissions. Twenty-one (47%) cases were classified as community-associated, while 17 (38%) were hospital associated. Seven (15%) were community-onset but hospital associated, with three of these associated with other veterinary hospitals. There was no increase in the incidence of overall or hospital-associated infections during the study period. The urinary tract was the most common site of infection (n511, 24%). Wound infections (excluding surgical site infections) accounted for 8 (18%) of infections, with superficial and deep surgical site infections accounting for 7 (16%) and organ/space surgical site infections accounting for another 2 cases. Urinary tract infections were most common among animals with CA infection, accounting for 8/21 (38%) cases with wound infections accounting for 4 (19%) cases. Of the 24 cases associated with the OVCTH, 17 (71%) had surgery, 15 (63%) were hospitalized in the intensive care unit, 10 (42%) had indwelling urinary catheters placed, and 20 (83%) had received antimicrobials prior to onset of infection. Risk factors for E. cloacae infection could not be determined because a noninfected control group was not evaluated. Surgical site infections accounted for 9 (38%) HA cases. Overall, only 2/11 (18%) urinary tract infections were associated with prior placement of a urinary catheter. Nine (20%) animals died or were euthanized and E. cloacae was implicated as a causative or contributing factor in 5 (56%) of those cases. Two main antimicrobial phenotype patterns were identified. One (n525) was characterized by susceptibility to fluoroquinolones, tetracycline, and trimethoprim with variable susceptibility to cefoxitin while the other (n514) was characterized by resistance to these antimicrobials. Prior administration of antimicrobials was associated with presence of the more resistant phenotype (P50.044) but there was no association between this phenotype and origin of infection (P50.74) and no increase in the prevalence of this phenotype from 2005 to 2007 (P50.97). Infections with this phenotype were not associated with nonsurvival (P50.74). There was no evidence of a, HA outbreak or increase in prevalence, yet identification of multidrug resistant E. cloacae in both CA and HA infections is concerning and requires ongoing surveillance. ABSTRACT #3 STAPHYLOCOCCUS PSEUDINTERMEDIUS: A NEWLY RECOGNIZED PATHOGEN IN DOGS AND CATS. MC Faires, D Slavic, JS Weese. Ontario Veterinary College, Animal Health Laboratory, University of Guelph, Guelph, Ontario.3 STAPHYLOCOCCUS PSEUDINTERMEDIUS: A NEWLY RECOGNIZED PATHOGEN IN DOGS AND CATS. MC Faires, D Slavic, JS Weese. Ontario Veterinary College, Animal Health Laboratory, University of Guelph, Guelph, Ontario. Staphylococcus intermedius has typically been regarded as the predominant pathogenic Staphylococcus spp in dogs and cats, and a leading cause of skin and soft tissue infections. In 2005, a novel Staphylococcus species, Staphylococcus pseudintermedius, was identified. This organism is closely related to, but distinct from, S. intermedius. Gene-sequence based methods are required to differentiate these two species; however, these techniques are rarely performed in clinical laboratories, and as a result the prevalence and characteristics of S. pseudintermedius are poorly understood. Recent evidence suggests that S. pseudintermedius may actually be the predominant Staphylococcus spp in dogs and cats but misidentified as S. intermedius by diagnostic laboratories. The objective of this study was to use sequence based methods to identify putative S. intermedius isolates from dogs and cats and to evaluate antimicrobial resistance and virulence factors among S. pseudintermedius isolates. Isolates from dogs and cats identified as S. intermedius by conventional laboratory methods were obtained from the University of Guelph Animal Health Laboratory. Isolates were collected in a serial manner without selection. DNA was extracted, sequencing of the sodA gene was performed, and isolates were identified via sequence alignment with reference staphylococcal strains through GenBank (www.ncbi.nlm.nih.gov/blast/BLAST.cgi). Antimicrobial susceptibility testing was performed and PCR was used to identify various virulence factors and antimicrobial genes. A total of 25 isolates were obtained from 21 dogs and 2 cats. Medical records were not available for 2 of the isolates. 25/25 (100%) were identified as S. pseudintermedius Severity of infection ranged from superficial dermatitis to rapidly fatal necrotizing fasciitis with the majority of isolates from otitis externa 9/23 (39.1%) and urinary tract infections 6/23 (26.1%). Antimicrobial susceptibility was as follows: amoxicillin/clavulanate 23/23 (100%), ampicillin 7/ 23 (30.4%), cephalothin 23/23 (100%), clindamycin 18/23 (78.3%), gentamicin 23/23 (100%), tetracycline 18/23 (78.3%), and trimethoprim/sulfa 19/23 (82.6%). Not all antimicrobials were tested for all isolates, based on laboratory protocols regarding antimicrobial panel and site of infection. Inducible resistance to clindamycin was detected by D-test in 1 isolate reported as clindamycin-susceptible (5.6%). Detection of virulence factors and antimicrobial resistance genes is ongoing. This study identified S. pseudintermedius as an important pathogen in dogs and cats, and suggests that S. intermedius may not be a major concern in these species. Further studies are required to evaluate clinically relevant virulence factors to assist in understanding the pathogenesis of disease caused by S. pseudintermedius. 70

Unilateral shunt formation with thoracic aortic dissection in a whippet

A three-year-old neutered male whippet was presented with intermittent, exercise-induced paraparesis. Femoral pulses were bilaterally absent. Neurologic examination was suggestive of a thoracolumbar myelopathy. Blood pressure measurements revealed hypotension in both pelvic limbs, hypertension in the right thoracic limb and it was immeasurable in the left thoracic limb. Echocardiography was within reference limits. A clear vascular pulsation was palpable on the right ventral abdominal wall. Computed tomographic angiography revealed a dissection of the aortic wall between the left subclavian artery and the brachiocephalic trunk with subsequent thrombus formation. A shunt between the right internal thoracic, cranial and caudal epigastric arteries to preserve blood flow to the pelvic limbs was visualized. Necropsy was declined by the owner. This is the first case report describing the formation of a unilateral vascular shunt following a thoracic aortic occlusion, which presented as exercise-induced paraparesis.