Patrick R. Kircher

Growth and wear of incisor and cheek teeth in domestic rabbits (Oryctolagus cuniculus) fed diets of different abrasiveness

Although patterns of tooth wear are crucial in palaeo-reconstructions, and dental wear abnormalities are important in veterinary medicine, experimental investigations on the relationship between diet abrasiveness and tooth wear are rare. Here, we investigated the effect of four different pelleted diets of increasing abrasiveness (due to both internal [phytoliths] and external abrasives [sand]) or whole grass hay fed for 2 weeks each in random order to 16 rabbits (Oryctolagus cuniculus) on incisor and premolar growth and wear, and incisor and cheek tooth length. Wear and tooth length differed between diets, with significant effects of both internal and external abrasives. While diet abrasiveness was linked to tooth length for all tooth positions, whole forage had an additional effect on upper incisor length only. Tooth growth was strongly related to tooth wear and differed correspondingly between diets and tooth positions. At 1.4-3.2 mm/week, the growth of cheek teeth measured in this study was higher than previously reported for rabbits. Dental abnormalities were most distinct on the diet with sand. This study demonstrates that concepts of constant tooth growth in rabbits requiring consistent wear are inappropriate, and that diet form (whole vs. pelleted) does not necessarily affect cheek teeth. Irrespective of the strong effect of external abrasives, internal abrasives have the potential to induce wear and hence exert selective pressure in evolution. Detailed differences in wear effects between tooth positions allow inferences about the mastication process. Elucidating feedback mechanisms that link growth to tooth-specific wear represents a promising area of future research.

THORACIC COMPUTED TOMOGRAPHY, ANGIOGRAPHIC COMPUTED TOMOGRAPHY, AND PATHOLOGY FINDINGS IN SIX CATS EXPERIMENTALLY INFECTED WITH AELUROSTRONGYLUS ABSTRUSUS

Aelurostrongylus abstrusus infection is common in endemic areas and may cause severe respiratory clinical signs. Computed tomography (CT) is an important tool to diagnose pulmonary disease, because it allows detection of small lesions and discrimination of superimposed structures. The purpose of this study was to characterize by CT and angiographic CT the pulmonary lesions in six cats before, and 48 and 81 days after inoculation with 100 or 800 A. abstrusus infective larvae. Histological examination of the accessory lung lobe was performed to determine the microscopic, pathomorphologic correlate of the CT findings. The predominant CT lesion consisted of multiple nodules of varying size distributed throughout the lungs, severity depending on infectious dose. The histological correlate of the nodular lesions was multifocal dense granulomatous to mixed inflammatory cell infiltrates, including eosinophils distributed in the parenchyma and obliterating the alveoli. Marked, multifocal, dose-dependent thickening of the bronchi and adjacent interstitial changes blurred the margins of the outer serosal surface of the bronchi and vessels. Histologically, this was due to peribronchial mixed cell inflammation. During the course of infection some of the nodular and peribronchial changes were replaced by areas of ground-glass opacity. In addition to providing detailed depiction of pulmonary lesions resulting from an infectious cause and clearly defining lesions with respect to time and severity of infection, CT allowed quantitative assessment of bronchial thickness and lymph node size during the course of disease. Findings indicated that CT characteristics of this disease are consistent with pathologic findings.

EFFECT OF CONTRAST MEDIUM INJECTION DURATION ON PEAK ENHANCEMENT AND TIME TO PEAK ENHANCEMENT OF CANINE PULMONARY ARTERIES

Our goal was to investigate the effect of contrast medium injection duration on pulmonary artery peak enhancement and time to peak enhancement. Fourteen dogs were allocated into one of seven predefined weight categories, each category contained two dogs. Dogs in each weight category were assigned to group A or B. Animals in each group received a different contrast medium injection protocol. In group A, a fixed injection rate of 5 ml/s was used. In group B, the contrast injection rate was calculated as follows: flow rate= contrast volume/scan duration + 10s. Time to peak enhancement and peak enhancement of the main left and right pulmonary arteries were measured on single-level, dynamic CT images for a fixed time of 30s. Rank correlation (Spearmans) coefficients between injection duration and time to peak enhancement and between body weight and peak enhancement were calculated. For group A, there was a significant negative correlation between peak enhancement and weight (r = -0.94; P = 0.005), while for group B, there was no significant correlation (r = -0.64 and P = 0.18). There was a significant correlation between time to peak enhancement and injection duration in both groups (group A: r = 0.99; P = 0.006 and group B: r = 0.85; P = 0.02). In conclusion, injection duration is a key feature in a CT angiography injection protocol. A protocol with an injection duration adjusted to the scan duration seems to be particularly suitable for veterinary applications where a population with great weight variability is studied.

Congenital hypothyroidism in a kitten resulting in decreased IGF-I concentration and abnormal liver function tests

A 7-month-old male kitten was presented with chronic constipation and retarded growth. Clinical examination revealed disproportional dwarfism with mild skeletal abnormalities and a palpable thyroid gland. The presumptive diagnosis of congenital hypothyroidism was confirmed by low serum total thyroxine (tT4) concentration prior to and after the administration of thyroid stimulation hormone (TSH), increased endogenous TSH concentration and abnormal thyroid scintigraphic scan. The kitten had abnormal liver function tests and decreased insulin-like growth factor 1 (IGF-1) concentration, both of which returned to normal in correspondence with an improvement of the clinical signs after 6 weeks of thyroxine therapy. Congenital hypothyroidism is a rare disease that may present with considerable variation in clinical manifestation. In cases in which clinical signs are ambiguous, disorders such as portosystemic shunt and hyposomatotropism have to be taken into account as differential diagnosis. As hypothyroidism may be associated with abnormal liver function tests and low IGF-1 concentrations, test results have to be interpreted carefully.

MAGNETIC RESONANCE IMAGING FEATURES OF SINONASAL DISORDERS IN HORSES

Diseases of paranasal sinuses and nasal passages in horses can be a diagnostic challenge because of the complex anatomy of the head and limitations of many diagnostic modalities. Our hypothesis was that magnetic resonance (MR) imaging would provide excellent anatomical detail and soft tissue resolution, and would be accurate in the diagnosis of diseases of the paranasal sinuses and nasal passages in horses. Fourteen horses were imaged. Inclusion criteria were lesions located to the sinuses or nasal passages that underwent MR imaging and subsequent surgical intervention and/or histopathologic examination. A low field, 0.3 tesla open magnet was used. Sequences in the standard protocol were fast spin echo T2 sagittal and transverse, spin echo T1 transverse, short-tau inversion recovery (STIR) dorsal, gradient echo 3D T1 MPR dorsal (plain and contrast enhanced), spin echo T1 fatsat (contrast enhanced). Mean scan time to complete the examination was 53 min (range 39-99 min). Lesions identified were primary or secondary sinusitis (six horses), paranasal sinus cyst (four horses), progressive ethmoid hematoma (two horses), and neoplasia (two horses). The most useful sequences were fast spin echo T2 transverse and sagittal, STIR dorsal and FE3D MPR (survey and contrast enhanced). Fluid accumulation, mucosal thickening, presence of encapsulated contents, bone deformation, and thickening were common findings observed in MR imaging. In selected horses, magnetic resonance imaging is a useful tool in diagnosing lesions of the paranasal sinuses and nasal passages.

Feasibility and safety of endoscopic ultrasound-guided fine needle aspiration of the pancreas in dogs

BACKGROUND Endoscopic ultrasound (EUS)-guided fine needle aspiration (EUS-FNA) has proven a useful and safe diagnostic tool for assessing pancreatic disease in human medicine. No information about pancreatic EUS-FNA is available in dogs. OBJECTIVES To assess the feasibility and safety of pancreatic EUS-FNA in healthy dogs. ANIMALS Thirteen beagles with a median body weight of 13.4 kg. METHODS Experimental study. An ultrasound endoscope (insertion tube outer diameter 11.8 mm) was used, and FNA was carried out with 19 G needles. The optimal puncture site was chosen with the aid of Doppler imaging. Complete clinicopathologic assessments including pain scoring and pancreas-specific lipase measurements were obtained before EUS as well as on day 1 and day 2 after EUS-FNA. RESULTS The pancreatic body was identified in all dogs, the left lobe was clearly identified in 9/13 and appeared indistinctly marginated in 4/13 dogs, and the distal third of the right lobe could not be identified in 7/13 dogs. EUS-FNA was carried out in 12/13 dogs. Cellularity of smears was adequate for evaluation in 8/12 cases, in which samples were obtained transgastrically (n = 4) or transduodenally (n = 4). All dogs recovered uneventfully and no clinical and laboratory abnormalities occurred during the 48 hour monitoring period after the procedure. CONCLUSION AND CLINICAL IMPORTANCE Although the healthy canine pancreas is difficult to visualize in its entirety with EUS, pancreatic EUS-FNA with a 19 G needle is feasible in medium-sized dogs and can be considered a safe procedure. Its diagnostic usefulness should be evaluated in dogs with pancreatic disease.

The Advanced Locking Plate System (ALPS): a retrospective evaluation in 71 small animal patients.

Objective To evaluate use of the Advanced Locking Plate System (ALPS) in dogs and cats and report outcome. Study Design Retrospective case series. Animals Dogs (n = 29) and cats (n = 42). Methods The medical records (April 2007–April 2010) of dogs and cats treated with ALPS were reviewed evaluated. Data retrieved included signalment, indication for surgery, complications, and outcome. Results ALPS was used for 54 fractures, 12 tarsal or carpal ligament injuries and in 6 cases, to prevent or treat fractures during total hip replacement. Complications needing revision surgery occurred in 4 cases (5.5%): fixation failure was identified in 3 (2 fracture-fixations, 1 pancarpal arthrodesis), and a fracture occurred through a screw hole. The most common complication after tarsal arthrodesis was suture dehiscence. All cases had healed by study end. Conclusions ALPS offers a reliable alternative for fracture treatment and some other orthopedic conditions in small animals.OBJECTIVE To evaluate use of the Advanced Locking Plate System (ALPS) in dogs and cats and report outcome. STUDY DESIGN Retrospective case series. ANIMALS Dogs (n = 29) and cats (n = 42). METHODS The medical records (April 2007-April 2010) of dogs and cats treated with ALPS were reviewed evaluated. Data retrieved included signalment, indication for surgery, complications, and outcome. RESULTS ALPS was used for 54 fractures, 12 tarsal or carpal ligament injuries and in 6 cases, to prevent or treat fractures during total hip replacement. Complications needing revision surgery occurred in 4 cases (5.5%): fixation failure was identified in 3 (2 fracture-fixations, 1 pancarpal arthrodesis), and a fracture occurred through a screw hole. The most common complication after tarsal arthrodesis was suture dehiscence. All cases had healed by study end. CONCLUSIONS ALPS offers a reliable alternative for fracture treatment and some other orthopedic conditions in small animals.

Urinary and plasma catecholamines and metanephrines in dogs with pheochromocytoma, hypercortisolism, nonadrenal disease and in healthy dogs.

Background Diagnosis of pheochromocytoma (PC) is based on a combination of clinical suspicion, finding an adrenal mass, increased plasma, and urine concentrations of catecholamine metabolites and is finally confirmed with histopathology. In human medicine, it is controversial whether biochemically testing plasma is superior to testing urine. Objectives To measure urinary and plasma catecholamines and metanephrines in healthy dogs, dogs with PC, hypercortisolism (HC), and nonadrenal diseases (NAD) and to determine the test with the best diagnostic performance for dogs with PC. Animals Seven PC dogs, 10 dogs with HC, 14 dogs with NAD, 10 healthy dogs. Methods Prospective diagnostic clinical study. Urine and heparin plasma samples were collected and stored at −80°C before analysis using high‐pressure liquid chromatography (HPLC) coupled to electrochemical detection or tandem mass spectrometry were performed. Urinary variables were expressed as ratios to urinary creatinine concentration. Results Dogs with PC had significantly higher urinary normetanephrine and metanephrine : creatinine ratios and significantly higher plasma‐total and free normetanephrine and plasma‐free metanephrine concentrations compared to the 3 other groups. There were no overlapping results of urinary normetanephrine concentrations between PC and all other groups, and only one PC dog with a plasma normetanephrine concentration in the range of the dogs with HC and NAD disease. Performances of total and free plasma variables were similar. Overlap of epinephrine and norepinephrine results between the groups was large with both urine and plasma. Conclusion and clinical importance Measurement of normetanephrine is the preferred biochemical test for PC and urine was superior to plasma.

In vivo proton magnetic resonance spectroscopy for the evaluation of hepatic encephalopathy in dogs

OBJECTIVE To investigate clinical use of proton magnetic resonance spectroscopy ((1)H MRS) and to compare metabolic brain bioprofiles of dogs with and without hepatic encephalopathy. ANIMALS 6 dogs with hepatic encephalopathy and 12 control dogs. PROCEDURES Conventional MRI and single-voxel (1)H MRS were performed with a 3-T magnet. Images for routine MRI planes and sequences were obtained. Single-voxel (1)H MRS was performed with a point-resolved sequence with a short echo time (35 milliseconds) and voxel of interest placement at the level of the basal ganglia. Metabolites of interest included the glutamine-glutamate complex (sum quantification of glutamate and glutamine), myoinositol, N-acetyl aspartate, total choline, and creatine. Data were analyzed with postprocessing fitting algorithm software, and metabolite concentration relative to water and ratios with creatine as the reference metabolite were calculated. RESULTS Compared with control dogs, dogs with hepatic encephalopathy had specific changes, which included significantly higher concentration relative to water of the glutamine-glutamate complex and significantly lower concentration of myoinositol. Choline and N-acetyl aspartate concentrations were also slightly lower in dogs with hepatic encephalopathy than in control dogs. No differences in creatine concentration were detected between groups. CONCLUSIONS AND CLINICAL RELEVANCE (1)H MRS aided in the diagnosis of hepatic encephalopathy in dogs, and findings supported the assumption that ammonia is a neurotoxin that manifests via glutamine-glutamate complex derangements. Use of (1)H MRS may provide clinically relevant information in patients with subclinical hepatic encephalopathy, equivocal results of bile acids tests, and equivocal ammonia concentrations or may be helpful in monitoring efficacy of medical management.

Regional metabolite concentrations in the brain of healthy dogs measured by use of short echo time, single voxel proton magnetic resonance spectroscopy at 3.0 Tesla

OBJECTIVE To investigate regional differences of relative metabolite concentrations in the brain of healthy dogs with short echo time, single voxel proton magnetic resonance spectroscopy ((1)H MRS) at 3.0 T. ANIMALS 10 Beagles. PROCEDURES Short echo time, single voxel (1)H MRS was performed at the level of the right and left basal ganglia, right and left thalamus, right and left parietal lobes, occipital lobe, and cerebellum. Data were analyzed with an automated fitting method (linear combination model). Metabolite concentrations relative to water content were obtained, including N-acetyl aspartate, total choline, creatine, myoinositol, the sum of glutamine and glutamate (glutamine-glutamate complex), and glutathione. Metabolite ratios with creatine as the reference metabolite were calculated. Concentration differences between right and left hemispheres and sexes were evaluated with a Wilcoxon signed rank test and among various regions of the brain with an independent t test and 1-way ANOVA. RESULTS No significant differences were detected between sexes and right and left hemispheres. All metabolites, except the glutamine-glutamate complex and glutathione, had regional concentrations that differed significantly. The creatine concentration was highest in the basal ganglia and cerebellum and lowest in the parietal lobes. The N-acetyl aspartate concentration was highest in the parietal lobes and lowest in the cerebellum. Total choline concentration was highest in the basal ganglia and lowest in the occipital lobe. CONCLUSIONS AND CLINICAL RELEVANCE Metabolite concentrations differed among brain parenchymal regions in healthy dogs. This study may provide reference values for clinical and research studies involving (1)H MRS performed at 3.0 T.