William Schall

Mutation causing von Willebrand's disease in Scottish Terriers.

Von Willebrands Disease (vWD) in the Scottish Terrier breed is a serious, often fatal, hereditary bleeding disorder. Elimination of the mutated gene by selective breeding is an important goal for the health of this breed. Although the standard protein-based tests are accurate for identification of affected Scottish Terriers, they are not reliable for the identification of carriers of the mutant gene unless multiple replicate assays are performed. A simple, highly accurate test for carriers of the disease is needed so that veterinarians can counsel clients on which animals to use in their breeding programs. The complete coding region of von Willebrand factor (vWF) complementary DNA (cDNA) was sequenced from an affected animal, and a single base deletion in the codon for amino acid 85 of the prepro-vWF cDNA that leads to Scottish Terrier vWD was identified. A highly accurate polymerase chain reaction assay was developed that can distinguish homozygous normal animals from those that are homozygous affected or heterozygous. In a voluntary survey of 87 animals provided by Scottish Terrier owners, 15 were carriers and 4 were affected with vWD, 2 of which had previously been shown to have undetectable vWF. The determination of the complete canine vWF cDNA sequence should facilitate the identification of additional vWD alleles in other breeds and other species.

Cyclosporine pharmacokinetics in normal and pancreatectomized dogs.

Oral and i.v. cyclosporine (Cs) pharmacokinetics determined from radioimmunoassay (RIA) data were compared in normal and pancreatectomized dogs. An altered pharmacokinetics of Cs was observed in the pancreatectomized dogs that include: a 170% larger central compartment volume; a 34% greater total-body clearance; and lower steady-state average serum concentrations relative to the normals. Even though there were marked intersubject variations, both groups displayed a triexponential decline in Cs serum concentrations and disposition kinetics. Following 7 daily oral doses of commercial cyclosporine (CsA) (20 mg/kg) the Cs serum trough concentrations of the pancreatectomized dogs were consistently below 100 ng/ml, while those of the normal dogs were above 400 ng/ml. No alteration of CsA oral absorption was noted following pancreatectomy. This study suggests that frequent serum Cs concentration monitoring, with appropriate dosage adjustments, even in normals, is necessary to assure adequate drug levels. More significantly, the CsA dosage for pancreatectomized dogs should be several times greater to maintain serum concentrations comparable to normal dogs.

Acquisition and persistence of antimicrobial-resistant bacteria isolated from dogs and cats admitted to a veterinary teaching hospital

OBJECTIVE To assess antimicrobial resistance among bacteria isolated from dogs and cats admitted to a veterinary teaching hospital (VTH), determine the incidence of acquisition of and frequency of persistent colonization by antimicrobial-resistant organisms among these animals, and identify risk factors associated with these variables. DESIGN Prospective longitudinal study. ANIMALS 622 dogs and 92 cats admitted to a VTH and expected to stay ≥ 48 hours. PROCEDURES Samples were collected with rectal and nasal or oropharyngeal swabs at admission and discharge. Isolates of enterococci, staphylococci, and Escherichia coli were tested for antimicrobial resistance via microbroth dilution methods. A subset of isolates was analyzed with pulsed-field gel electrophoresis and multilocus sequence typing. Significant trends in proportions of organisms with antimicrobial resistance over the 3-year study period were assessed. RESULTS The proportion of staphylococci with antimicrobial resistance increased, whereas the proportion of E coli with resistance decreased, over time; resistance among enterococci was more variable. For 506 dogs with paired admission and discharge samples, multidrug-resistant (MDR) E coli was acquired by 40 (8%) and methicillin-resistant Staphylococcus aureus (MRSA) was acquired by 7 (1.4%); hospitalization for > 3 days was significantly associated with both variables. Most (5/7 isolates) acquired MRSA was of sequence type (ST) 5. CONCLUSIONS AND CLINICAL RELEVANCE Extended hospitalization was associated with increased risk of acquiring MDR E coli or MRSA, although few animals acquired MRSA. It is unclear whether associations were confounded by illness severity or use of infection control measures. Additionally, MRSA of ST5, which has been associated with small animal medicine, was the most commonly acquired MRSA in this study.

Prevalence and antimicrobial resistance of Enterococcus spp and Staphylococcus spp isolated from surfaces in a veterinary teaching hospital

OBJECTIVE To determine the prevalence and antimicrobial resistance of enterococci and staphylococci collected from environmental surfaces at a veterinary teaching hospital (VTH). DESIGN Longitudinal study. SAMPLE Samples collected from surfaces in 5 areas (emergency and critical care, soft tissue and internal medicine, and orthopedic wards; surgery preparation and recovery rooms; and surgery office and operating rooms) of a VTH. PROCEDURES Selected surfaces were swabbed every 3 months during the 3-year study period (2007 to 2009). Isolates of enterococci and staphylococci were identified via biochemical tests, and antimicrobial susceptibility was evaluated with a microbroth dilution technique. A subset of isolates was analyzed to assess clonality by use of pulsed-field gel electrophoresis. RESULTS 430 samples were collected, and isolates of enterococci (n = 75) and staphylococci (110) were identified. Surfaces significantly associated with isolation of Enterococcus spp and Staphylococcus spp included cages and a weight scale. Fourteen Enterococcus spp isolates and 17 Staphylococcus spp isolates were resistant to ≥ 5 antimicrobials. Samples collected from the scale throughout the study suggested an overall increase in antimicrobial resistance of Enterococcus faecium over time. Clonality was detected for E faecium isolates collected from 2 different surfaces on the same day. CONCLUSIONS AND CLINICAL RELEVANCE Although not surprising, the apparent increase in antimicrobial resistance of E faecium was of concern because of the organisms ability to transmit antimicrobial resistance genes to other pathogens. Results reported here may aid in identification of critical control points to help prevent the spread of pathogens in VTHs.

Acquired Proximal Renal Tubular Dysfunction in 9 Labrador Retrievers with Copper-Associated Hepatitis (2006–2012)

BACKGROUND Copper-associated hepatitis (CAH) has been well described in Labrador Retrievers. However, the association of CAH with proximal renal tubular dysfunction in this breed has not been characterized. OBJECTIVES To report clinical features, hepatic and renal histopathologic findings, tissue copper concentrations, and outcome of Labradors with CAH and proximal renal tubular disease. ANIMALS Nine Labrador Retrievers with renal glucosuria and biopsy-confirmed CAH. METHODS Clinical, clinicopathologic, and light microscopic findings were retrospectively reviewed. Rhodanine staining or atomic emission spectroscopy was performed on all hepatic samples and available renal tissue (4 dogs) to assess copper concentrations. RESULTS Eight dogs had a history of polyuria and polydipsia, and all dogs had increased serum bilirubin concentrations. Five dogs had hyperchloremic metabolic acidosis. Three dogs with acidemia had paradoxical alkalinuria. All renal specimens had increased copper concentrations. Renal tubular vacuolization, degeneration, and regeneration were observed on light microscopy. Four dogs died within 10 days of diagnosis. One dog survived 2 months; 4 dogs survived more than 1 year. In long-term survivors, including 2 that did not undergo immediate copper chelation, resolution of renal tubular dysfunction occurred within weeks to months. CONCLUSIONS AND CLINICAL IMPORTANCE Labrador Retrievers with CAH can develop clinical and laboratory evidence of renal tubular dysfunction in association with increased renal copper concentrations. Given the rarity of renal tubular disorders, detection of renal glucosuria and increased ALT activity in a Labrador Retriever is suggestive of CAH. Although renal tubular dysfunction may indicate advanced disease, successful long-term outcome is possible with a variety of therapies.

Pharmacokinetics and relative bioavailability of D-penicillamine in fasted and nonfasted dogs.

BACKGROUND D-Penicillamine is the most commonly used copper-chelating agent in the treatment of copper-associated hepatitis in dogs. Response to therapy can be variable, and there is a lack of pharmacokinetic information available for dogs. Coadministering the drug with food to alleviate vomiting has been recommended for dogs, which contradicts recommendations for drug administration to humans. HYPOTHESIS Coadministration of d-penicillamine with food decreases relative bioavailability and maximum plasma drug concentrations (C(max)) in dogs. ANIMALS Nine purpose-bred dogs with a median body weight of 17.0 kg. METHODS Dogs received D-penicillamine (12.5 mg/kg PO) fasted and with food in a randomized, crossover design. Blood samples were collected before and 0.25, 0.5, 1, 2, 3, 4, 8, 12, and 24 hours after dosing. Total d-penicillamine concentrations were measured using liquid chromatography coupled with tandem quadrupole mass spectrometry. Pharmacokinetic parameters were calculated for each dog. RESULTS Two fasted dogs (22%) vomited after receiving d-penicillamine. Mean C(max) ± standard deviation (SD) was 8.7 ± 3.1 μg/mL (fasted) and 1.9 ± 1.6 μg/mL (fed). Mean area under the plasma concentration curve ± SD was 16.9 ± 5.9 μg/mL·h (fasted) and 4.9 ± 3.4 μg/mL·h (fed). There were significant reductions in relative bioavailability and C(max) in fed dogs (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE Coadministration of d-penicillamine with food significantly decreases plasma drug concentrations in dogs. Decreased drug exposure could result in decreased copper chelation efficacy, prolonged therapy, additional cost, and greater disease morbidity. Administration of d-penicillamine with food cannot be categorically recommended without additional studies.

Pharmacologic evaluation of ammonium tetrathiomolybdate after intravenous and oral administration to healthy dogs

OBJECTIVE To evaluate pharmacokinetics of ammonium tetrathiomolybdate (TTM) after IV and oral administration to dogs and effects of TTM administration on trace mineral concentrations. ANIMALS 8 adult Beagles and Beagle crossbreds (4 sexually intact males and 4 sexually intact females). PROCEDURES Dogs received TTM (1 mg/kg) IV and orally in a randomized crossover study. Serum molybdenum and copper concentrations were measured via inductively coupled plasma mass spectrometry in samples obtained 0 to 72 hours after administration. Pharmacokinetics was determined via noncompartmental analysis. RESULTS For IV administration, mean ± SD terminal elimination rate constant, maximum concentration, area under the curve, and half-life were 0.03 ± 0.01 hours(-1), 4.9 ± 0.6 μg/mL, 30.7 ± 5.4 μg/mL•h, and 27.7 ± 6.8 hours, respectively. For oral administration, mean ± SD terminal elimination rate constant, time to maximum concentration, maximum concentration, area under the curve, and half-life were 0.03 ± 0.01 hours(-1), 3.0 ± 3.5 hours, 0.2 ± 0.4 μg/mL, 6.5 ± 8.0 μg/mL•h, and 26.8 ± 8.0 hours, respectively. Oral bioavailability was 21 ± 22%. Serum copper concentrations increased significantly after IV and oral administration. Emesis occurred after IV (2 dogs) and oral administration (3 dogs). CONCLUSIONS AND CLINICAL RELEVANCE Pharmacokinetics for TTM after a single IV and oral administration was determined for clinically normal dogs. Absorption of TTM after oral administration was variable. Increased serum copper concentrations suggested that TTM mobilized tissue copper. Further studies will be needed to evaluate the potential therapeutic use of TTM in copper-associated chronic hepatitis of dogs.

Caudal vena cava kinking in dogs with ascites.

A 9-year-old dog with spontaneous ascites was found to have hepatic vein distension and a tortuous vena cava on abdominal ultrasound. In right lateral recumbency, the caudal vena cava crossed the diaphragm and became kinked before entering into the right atrium. Following this observation, we performed an experimental study in a normal dog to determine whether kinking of the caudal vena cava could be the result and not the cause of ascites. Ascites was induced using warm saline injected through a needle inserted into the abdominal cavity. Venograms were collected from different body positions, under four conditions: before and after a total of one, two and 3 liters of saline had been injected. Caudal vena cava kinking was observed in the experimental dog after 2 liters of fluid had been injected. Vena cava obstruction may cause ascites, but we found that sometimes caudal vena cava kinking can be the result and not the cause of the peritoneal effusion.