Mulenda Tshamala

Changes in sex hormone receptors during administration of progesterone to prevent estrus in the bitch.

The development of lesions and the changes in sex hormone receptors were studied in the uteri of bitches under progesterone treatment. Twelve weeks after the onset of treatment, there was atrophy of the endometrium and increased thickness of the myometrium, without cystic dilatation of endometrial glands. This was accompanied by a dramatic reduction in estrogen-alpha and progesterone receptors in all cell types of the uterine wall. By 24 weeks after the onset of treatment, however, the endometrium was thickened due to the development of cysts of endometrial glands, while the myometrium thickness had returned to normal. The estrogen-alpha and progesterone receptors in most cell types of the uterine wall were again within the normal range. These results clarify and reconcile some apparent contradictions in the literature. They show that sex hormone receptors in most cell types of the uterine wall, especially endometrial gland cells and stromal cells, escape progestin (down) regulation after prolonged exogenous administration of progesterone.

Surgical Treatment of a Canine Intranasal Meningoencephalocele

OBJECTIVE To report the clinical signs, diagnosis, and surgical treatment of an intranasal meningoencephalocele in a dog. STUDY DESIGN Case report. ANIMAL Female Border collie, 5 months old. METHODS A right intranasal meningoencephalocele was identified by computed tomography and magnetic resonance imaging. RESULTS The lesion was approached by a modified transfrontal craniotomy. Surgical closure of the defect at the level of the cribriform plate and removal of extruded brain tissue resulted in regression of lacrimation and coincided with absence of seizuring. Treatment with phenobarbital was gradually reduced and stopped at 7 months after surgery. At 28 months the dog remained free of seizures. CONCLUSION Meningoencephalocele, although rare, can cause seizures in dogs and can be treated surgically. CLINICAL RELEVANCE A transfrontal craniotomy with excision of the meningoencephalocele and closure of the defect can be an effective treatment for an intranasal meningoencephalocele in dogs.

Surgical Treatment of Disk‐Associated Wobbler Syndrome by a Distractable Vertebral Titanium Cage in Seven Dogs

OBJECTIVE To evaluate a distractable titanium cage for the treatment of disk-associated wobbler syndrome (DAWS). STUDY DESIGN Prospective study. ANIMALS Dogs (n = 7) with DAWS. METHODS After total discectomy of C5-C6 and C6-C7, the median part of the vertebral body of C6 was removed with preservation of the lateral walls and dorsal cortex. The removed cancellous bone was collected. The implant was placed in the bony defect of C6. After placement, the titanium cage was distracted and affixed by 4 screws. Finally, the implant was filled and covered with cancellous bone. Dogs had follow-up examinations at 1, 3, 6, 12, and 24 months. Six months after surgery, cervical radiographs and computed tomography (CT) were performed. RESULTS Although no intraoperative complications occurred, correct placement of the cage was technically challenging. Revision surgery was necessary in 2 dogs because of implant loosening and aggravation of vertebral tilting. All dogs improved after discharge from the hospital. In 1 dog, recurrence of clinical signs caused by articular facet proliferation at an adjacent intervertebral disk space occurred. Radiographs at 6 months demonstrated cage subsidence in 4 dogs. In all dogs, CT was suggestive for fusion of the bone graft with the vertebral body. CONCLUSIONS Although results are promising, technical adaptations will be necessary to make this specific surgical technique, designed for humans, suitable for routine use in dogs.

Effects of sedative and hypnotic drug combinations on transcranial magnetic motor evoked potential, bispectral index and ARX-derived auditory evoked potential index in dogs

Relationships between onset latency and peak-to-peak amplitude of magnetic motor evoked potentials (MMEP) after transcranial magnetic stimulation (TMS), together with the electroencephalographic parameters bispectral analysis index (BIS) and the autoregressive model with exogenous input (ARX)-derived auditory evoked potential index (AAI) were explored during different sedative and hypnotic drug combinations in six dogs. TMS was performed under sedation with acepromazine/methadone or medetomidine and after a single bolus injection of propofol or etomidate. Data for BIS and AAI were continuously collected during the periods of treatment with the hypnotic drugs. Changes in BIS and AAI during both periods were not statistically correlated with changes in onset latencies and peak-to-peak amplitudes of MMEP after TMS. Therefore, both electroencephalographic techniques are of limited use in titrating sedation and anaesthesia during TMS in the dog.

Magnetic stimulation of the radial nerve in dogs and cats with brachial plexus trauma: A report of 53 cases

Brachial plexus trauma is a common clinical entity in small animal practice and prognostic indicators are essential early in the course of the disease. Magnetic stimulation of the radial nerve and consequent recording of the magnetic motor evoked potential (MMEP) was examined in 36 dogs and 17 cats with unilateral brachial plexus trauma. Absence of deep pain perception (DPP), ipsilateral loss of panniculus reflex, partial Horners syndrome and a poor response to MMEP were related to the clinical outcome in 29 of the dogs and 13 of the cats. For all animals, a significant difference was found in MMEP between the normal and the affected limb. Absence of DPP and unilateral loss of the panniculus reflex were indicative of an unsuccessful outcome in dogs. Additionally, the inability to evoke a MMEP was associated with an unsuccessful outcome in all animals. It was concluded that magnetic stimulation of the radial nerve in dogs and cats with brachial plexus trauma may provide an additional diagnostic and prognostic tool.

Regional brain perfusion changes during standard and microburst vagus nerve stimulation in dogs

PURPOSE Vagus nerve stimulation (VNS) is an effective adjunctive treatment for refractory epilepsy in humans, but its mechanism of action (MOA) and optimal stimulation parameters are still unknown. Functional neuroimaging studies could provide better insight into the brain structures involved in the activity of VNS, but have not yet been described in dogs. The aim of this study was to investigate the effect of acute VNS on the regional cerebral blood flow (rCBF) in dogs using micro-SPECT (μ-SPECT). Additionally, a novel stimulation paradigm (microburst VNS) was used and compared with standard VNS. METHODS A VNS Therapy System was implanted in ten Beagle dogs. μ-SPECT was performed after sham, standard and microburst VNS in a randomized, cross-over study. Nineteen volumes of interest (VOIs) were semi-quantitatively analysed and perfusion indices (PIs) were calculated. Furthermore, a rostro-caudal gradient (R-C), an asymmetry index (AI) and a cortical-subcortical index (Co-SCo) were determined. The SPECT results after standard and microburst VNS were compared pairwise with sham stimulation. RESULTS Acute standard VNS did not cause significant rCBF alterations. Acute microburst VNS caused a significant hypoperfusion in the left frontal lobe (P=0.023) and in the right parietal lobe (P=0.035). Both stimulation paradigms did not cause changes in R-C, AI nor Co-SCo. CONCLUSIONS Microburst VNS is more potent than standard VNS to modulate the rCBF in the dog. Our results promote further research towards the antiepileptic effect of microburst VNS in dogs and humans.

Vagus Nerve Stimulator Placement in Dogs: Surgical Implantation Technique, Complications, Long‐Term Follow‐Up, and Practical Considerations

OBJECTIVE To describe a modified implantation procedure of a vagus nerve stimulation (VNS) device in dogs and to report short- and long-term complications. STUDY DESIGN Descriptive, experimental study. ANIMALS Healthy, adult Beagle dogs (n = 10). METHODS A VNS Therapy(®) System was implanted in the left cervical region of anesthetized dogs. During and within 48 hours after surgery, electrocardiography (ECG) and impedance testing of the system were performed. Dogs were monitored daily and the impedance of the system was determined regularly until VNS devices were surgically removed 3 years after implantation. RESULTS The implantation procedure was successful in all dogs without intraoperative complications. ECG monitoring and impedance tests were within normal limits during and within 48 hours after surgery. Postoperative seroma formation was common (70%). One dog developed an irreversible Horners syndrome leading to removal of the device 5 months after implantation. Another dog developed trauma-induced damage of the lead requiring surgical revision. The device could be safely removed in all dogs; however, electrodes were left in place to avoid nerve damage. At removal, the anchor tether was dislodged in 40% of dogs and the lead was twisted in 50% of dogs. CONCLUSION Implantation of a VNS Therapy(®) System is safe and feasible in dogs; however, seroma formation, twisting of the lead, and dislodgement of the anchor tether were common. Practical improvements in the technique include stable device placement, use of a compression bandage, and exercise restriction. Regular evaluation of lead impedance is important, as altered values can indicate serious complications.

The use of epostane in an attempt to reproduce cystic endometrial hyperplasia in the bitch

The aetiology and pathogenesis of spontaneous cystic endometrial hyperplasia (CEH) in the bitch is not yet completely understood. Recent research based on the expression of uterine sex hormone receptors in spontaneous cases of CEH suggested that a temporary progesterone deficiency during late oestrus-early metoestrus may be responsible for the onset of CEH development. In the present study a temporary progesterone deficiency during late oestrus–early metoestrus was experimentally created using an inhibitor of progesterone synthesis, epostane. At day 49 of metoestrus, there was a significant reduction in the size of the uterine wall, mainly due to endometrial atrophy, and there was also a significant increase in the mucus-filled uterine lumen in the bitches that had been treated with epostane compared to the control bitches. No significant differences in the expression of sex hormone receptors was observed between the two groups. As no CEH developed in the epostane-treated bitches, an additional oestrogenic stimulus may be required to stimulate endometrial proliferation. Therefore, it is suggested that deficient luteinization of the corpus luteum may be the trigger in the pathogenesis of CEH, as the secretion of varying amounts of sex steroids depends on the degree of luteinization.

Short-and-long-term outcome in 63 dogs treated conservatively or surgically for disc associated wobbler syndrome

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