Oral cinacalcet administration decreases serum ionized calcium and parathyroid hormone concentrations in healthy dogs.

Cinacalcet is an oral calcimimetic that has potential to non-invasively treat primary hyperparathyroidism in dogs (Canis lupis familiaris). There is minimal data assessing its efficacy in dogs. This study aimed to determine whether a single dose of cinacalcet decreases serum ionized calcium (iCa), total calcium (tCa), and parathyroid hormone (PTH) concentrations. Twelve dogs received a median dose of 0.49 mg/kg (range 0.30-0.69 mg/kg) cinacalcet per os. Venous blood samples were collected at time 0 (before cinacalcet administration), 3, 8, and 24 h following cinacalcet administration. PTH, iCa, and tCa concentrations were measured at each time point and compared to 0 hour concentrations. A significant (50%) decrease in serum PTH occurred at 3 h with a median PTH of 4.6 pmol/L (range 2.7-10.8) at baseline and 1.65 pmol/L (range 0.5-14.7) at 3 h; p = .005. A significant, but not clinically relevant, decrease in serum iCa from a median baseline of 1.340 mmol/L (range 1.32-1.41) to a 3 h median of 1.325 mmol/L (range 1.26-1.39), p = .043, was also observed. tCa concentrations were not different. This study showed that a single dose of cinacalcet leads to transient decreases in iCa and PTH concentrations in healthy dogs.

Environmental radon, fracking wells, and lymphoma in dogs.

BACKGROUND: Multicentric lymphoma (ML) in dogs resembles non-Hodgkin lymphoma (NHL) in humans. Human NHL is associated with multiple environmental exposures, including to radon and volatile organic compounds (VOCs). HYPOTHESIS/OBJECTIVES: The objective of this study was to determine whether ML in dogs was associated with environmental radon or proximity to horizontal oil and drilling (fracking), a source of VOC pollution. METHODS: We identified dogs from the Golden Retriever Lifetime Study that developed ML (n = 52) along with matched controls (n = 104). Dog home addresses were categorized by Environmental Protection Agency radon zone and average residential radon by county, as well as by distance from fracking and associated wastewater wells. RESULTS: We found no significant differences in county level radon measurements. Individual household radon measurements were not available. There was no difference in residential proximity to active fracking wells between dogs with ML and unaffected dogs. While dogs with ML lived closer to wastewater wells (123 vs 206 km; P = .01), there was no difference in the percentage of cases vs controls that lived in close proximity (20 km) to a fracking well (11.5% for cases, 6.7% for controls; OR 1.81, 95% CI 0.55 to 5.22; P = .36), or a wastewater well (6.7% for cases, 4.4% for controls; P > .99). CONCLUSIONS AND CLINICAL IMPORTANCE: These data suggest that more proximate sources of chemical exposures need to be assessed in dogs with ML, including measurements of individual household radon and household VOC concentrations.

Urinary and household chemical exposures in pet dogs with urothelial cell carcinoma.

Urothelial cell carcinoma (UCC) has been linked to environmental chemical exposures in people, but these risk factors are not well understood in dogs with UCC. We hypothesised that household chemical exposures contribute to the risk of UCC in pet dogs. This prospective cross-sectional case-control study included 37 dogs with UCC and 37 unaffected breed-, sex-, and age-matched controls. Dog owners completed an environmental questionnaire and household samples were collected and analysed for arsenic (in tap water and room dust) and acrolein (in room air). Urine samples from UCC dogs, control dogs, and consenting owners were analysed for inorganic arsenic species, the acrolein metabolite 3-HPMA, and the phenoxy herbicide 2,4-D. Public data on chlorination byproducts (total trihalomethanes) in municipal drinking water were also compared between case and control households. Dogs with UCC were more likely to swim in a pool (15.2%) compared with control dogs (0%) (OR 1.69, 95% CI = 1.69-∞; p = .02). Dogs with UCC also had more than 4-fold higher reported municipal water concentrations of chlorination byproducts (median 28.0 ppb) compared with controls (median 6.9 ppb; p < .0001). Dust arsenic concentrations were unexpectedly lower in case households (median 0.277 ng/cm2) compared with control households (median 0.401 ng/cm2; p = .0002). Other outcomes were not significantly different between groups. These data suggest that dog owners, especially those of breeds known to be at higher risk for UCC, consider limiting access to swimming pools and installing water filtration units that remove total trihalomethanes.

Potential mechanism for hyperhomocysteinemia in Greyhound dogs.

BACKGROUND: Greyhounds have been reported to have hyperhomocysteinemia (HHC), but the underlying mechanisms and clinical implications are unclear. HYPOTHESIS: Our primary aim was to assess serum concentrations of homocysteine (HCy) and related analytes in Greyhounds and to identify a likely metabolic pathway for HHC. A secondary aim was to determine whether HHC is associated with evidence of oxidative stress. ANIMALS: Healthy pet Greyhounds (n = 31) and non-sighthound control dogs (n = 15). METHODS: Analysis of serum HCy, cobalamin, folate, and methionine, and plasma cysteine, glutathione, and total 8-isoprostane concentrations. RESULTS: Homocysteine concentrations were higher in Greyhounds (median, 25.0 µmol/L) compared to controls (13.9 µmol/L; P < .0001). Cobalamin concentrations were lower in Greyhounds (median, 416 ng/L) compared to controls (644 ng/L; P = .004) and were inversely correlated with HCy (r = -0.40, P = .004). Serum concentrations of folate, which is regenerated when HCy is converted to methionine, also were inversely correlated with HCy (r = -0.47, P = .002). Serum methionine concentrations were more than 4-fold lower in Greyhounds (median, 3.2 µmol/L) compared to controls (median, 15.0 µmol/L), but this difference was not significant (P = .3). Plasma cysteine, glutathione, and 8-isoprostane concentrations did not differ significantly between groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Our findings suggest a primary defect in conversion of HCy to methionine in Greyhounds, with related impaired folate generation. Ineffective cycling by methionine synthase could lead to secondary cobalamin depletion. Notably, low serum folate and cobalamin concentrations can be observed in Greyhounds without signs of intestinal disease.

Genotoxicity from metronidazole detected in vitro, but not in vivo, in healthy dogs in a randomized clinical trial.

OBJECTIVE: To determine whether metronidazole (MTZ), at recommended therapeutic dosages in dogs, induces peripheral blood cell (PMBC) genotoxicity, using the γ-H2AX assay as a sensitive measure of DNA breaks. The secondary aim was to assess dose-dependent genotoxicity in vitro in dog and cat PBMCs exposed to increasing MTZ concentrations. ANIMALS: 12 healthy employee- and student-owned dogs and blood samples from 2 other healthy untreated dogs and 2 healthy untreated cats. PROCEDURES: Screened dogs were randomized to receive lower-dose MTZ (7.5 mg/kg, PO, q 12 h) or higher-dose MTZ (20 mg/kg, PO, q 12 h) for 7 days. Blood was drawn at baseline, after the 1 week of treatment, and after a 1-week washout, for DNA damage assessment and serum MTZ concentration measurements. For in vitro studies, PBMCs from untreated healthy dogs and cats were exposed to 0 to 500 µg/mL MTZ. RESULTS: No dogs showed a significant increase in DNA damage at these MTZ dosages for 1 week. The highest serum MTZ concentration observed 1 hour after dosing was 36 µg/mL. In vitro, MTZ led to a significant increase in DNA damage at 100 µg/mL in both canine and feline PBMCs. CLINICAL RELEVANCE: Although MTZ was not significantly genotoxic in vivo in the healthy dogs in this study, MTZ was significantly genotoxic to canine PBMCs in vitro at 3-fold higher concentrations than those documented in vivo. The safety of MTZ in clinically ill dogs, which may have impaired MTZ clearance or DNA repair, should be assessed next.

Environmental exposures and lymphoma risk: a nested case-control study using the Golden Retriever Lifetime Study cohort.

Lymphoma is the second most common cancer affecting Golden Retrievers and is hypothesized to arise through a complex interaction of genetic and environmental factors. The aim of this nested case-control study was to investigate the association between potential environmental pollutant sources and lymphoma risk among Golden Retrievers participating in the Golden Retriever Lifetime Study. Forty-nine Golden Retrievers with non-cutaneous lymphoma and 98 Golden Retrievers without a history of cancer matched by age, sex and neuter status were selected from the Golden Retriever Lifetime Study cohort. Geographic proximity between each dog's primary residence and nine potential sources of environmental pollution was determined. In addition, the average annual ozone and airborne fine particulate matter levels for each dog's county of residence and owner-reported secondhand smoke exposure were evaluated. Environmental pollution sources of interest included chemical plants, municipal dumps, manufacturing plants, incineration plants, railroad embankment tracks, landfills, coal plants, high-voltage transmission lines, and nuclear power plants. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for each exposure of interest. Subgroup analyses were conducted to evaluate whether associations differed among 1) dogs with multicentric lymphoma, 2) dogs with B-cell lymphoma, and 3) dogs with T-cell lymphoma. No variables reached statistical significance when evaluating all cases together. However, cumulative exposure burden (household proximity to 3 or more pollution sources) approached significance within the multicentric lymphoma subgroup (OR = 2.60, 95%CI 0.99-6.86, p-value = 0.053). Patterns emerged among B- and T-cell subgroups, but none reached statistical significance. Ongoing research is warranted to discern if different environmental mechanisms may be driving B- and T-cell lymphoma immunophenotypes, consistent with previously reported regional differences in subtype prevalence.

Lymphoma is a common cancer affecting dogs, particularly Golden Retrievers. By identifying risk factors for lymphoma, work can be done to reduce harmful exposures or increase monitoring among dogs at a higher risk of disease. Using a subset of dogs from the Golden Retriever Lifetime Study, we sought to investigate whether dogs with lymphoma were more likely to live near certain environmental pollutant sources than dogs without lymphoma.Forty-nine Golden Retrievers with non-cutaneous lymphoma and 98 Golden Retrievers without a history of cancer were selected from the Golden Retriever Lifetime Study Cohort. We evaluated how close each dog lived to nine environmental pollutant sources: chemical plants, municipal dumps, manufacturing plants, incineration plants, railroad embankment tracks, landfills, coal plants, high-voltage transmission lines, and nuclear power plants. Additionally, we evaluated individual exposure to secondhand smoke, and average annual ozone and particulate matter exposure (as surrogate measures for air pollution) for each dog's county of residence.None of the exposures examined were associated with an increased lymphoma risk in this population. More research is needed, including direct biomonitoring, to determine whether specific environmental exposures are associated with lymphoma in the Golden Retriever breed.

Incidence of hepatopathies in dogs administered zonisamide orally: A retrospective study of 384 cases.

BACKGROUND: Acute hepatopathy secondary to administration of zonisamide has been reported in 2 dogs, but overall incidence of hepatopathy is unknown. OBJECTIVE: To characterize the incidence of hepatopathy in dogs administered zonisamide PO. ANIMALS: Three hundred eighty-four dogs administered zonisamide PO. METHODS: Multicenter retrospective study. Medical records were searched for dogs prescribed zonisamide PO and which had follow-up for at least 3 months (acute exposure) and >3 months (chronic exposure). Reported clinical signs, physical examination findings, and serum biochemical panels were reviewed for possible hepatotoxicosis. Serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activity and albumin concentration were documented for all available cases. RESULTS: Acute clinical hepatopathy was found in 2 of 384 treated dogs (0.52%, 95% confidence interval [CI], 0.06-1.9) after 13-16 days of zonisamide treatment. One additional dog had elevated serum ALT activity with no clinical signs. Of these 3 dogs, 2 recovered after administration of zonisamide was stopped, and 1 was euthanized because of liver failure. Of the 117 cases chronically administered zonisamide, 10 had an increase in ALP, 6 had an increase in ALT, and 1 had hypoalbuminemia. No clinical signs of liver disease were noted in dogs chronically treated with zonisamide (median, 20 months; range, 5-94 months). CONCLUSIONS AND CLINICAL IMPORTANCE: Acute, potentially life-threatening hepatopathy associated with oral administration of zonisamide to dogs is estimated to occur in less than 1% of dogs and was observed in the first 3 weeks of treatment. Subclinical abnormalities in ALT and ALP activity were noted in <10% of dogs during chronic administration of zonisamide, with no clinical signs of liver disease noted.

Plasma and urinary F2-isoprostane markers of oxidative stress are increased in cats with early (stage 1) chronic kidney disease.

OBJECTIVES: Oxidative stress contributes to chronic kidney disease (CKD) progression in humans and rodent models; F2-isoprostanes (F2-IsoPs) are established biomarkers of oxidative stress. Our primary aim was to evaluate plasma F2-IsoPs in cats with International Renal Interest Society stage 1 and 2 CKD, compared with healthy cats, and to determine whether plasma and urinary F2-IsoPs are equivalent biomarkers. The secondary aim was to assess whether consumption of a renal diet enriched in omega-3 fatty acids led to improvements in plasma and urinary F2-IsoPs. METHODS: Plasma and urinary F2-IsoPs were measured in 24 cats with stage 1 or 2 CKD, and 12 unaffected controls aged ⩾6 years. Twelve CKD cats were re-evaluated after feeding a commercial renal diet for at least 4 weeks. RESULTS: Median plasma F2-IsoPs were significantly higher in stage 1 CKD (96.2 pg/ml), early stage 2 CKD (83.2 pg/ml) and late stage 2 CKD (80.8 pg/ml) compared with healthy cats (22.8 pg/ml; P = 0.03-0.002). Median urinary F2-IsoPs were significantly higher in cats with stage 1 CKD (231.2 pg/mg) compared with healthy cats (152.5 pg/mg) or cats with late stage 2 CKD (124.8 pg/mg; P = 0.01). Plasma F2-IsoPs remained increased, while urinary F2-IsoPs fell with transition from stage 1 to stage 2 CKD. Feeding a commercial renal diet led to significant decreases in plasma F2-IsoPs in the small group of cats with stage 1 CKD (25-75% decrease) compared with cats with stage 2 CKD (20% decrease to 53% increase; P = 0.01). CONCLUSIONS AND RELEVANCE: Oxidative stress is prominent in cats with stage 1 CKD. Plasma and urinary F2-IsoPs are not interchangeable biomarkers in cats with stage 2 CKD. Placebo-controlled studies are indicated to evaluate dietary or pharmacologic doses of omega-3 fatty acids on redox stress and progression of renal dysfunction in cats with stage 1 CKD.

Biochemical, functional, and histopathologic characterization of lomustine-induced liver injury in dogs.

OBJECTIVE: To characterize the biochemical, functional, and histopathologic changes associated with lomustine-induced liver injury in dogs. ANIMALS: I0 healthy purpose-bred sexually intact female hounds. PROCEDURES: Dogs were randomly assigned to receive lomustine (approx 75 mg/m2, PO, q 21 d for 5 doses) alone (n = 5) or with prednisone (approx 1.5 mg/kg, PO, q 24 h for 12 weeks; 5). For each dog, a CBC, serum biochemical analysis, liver function testing, urinalysis, and ultrasonographic examination of the liver with acquisition of liver biopsy specimens were performed before and at predetermined times during and after lomustine administration. Results were compared between dogs that did and did not receive prednisone. RESULTS: 7 of the I0 dogs developed clinical signs of liver failure. For all dogs, serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, bile acid concentrations, and liver histologic score increased and hepatic reduced glutathione content decreased over time. Peak serum ALT (r = 0.79) and ALP (r = 0.90) activities and bile acid concentration (r = 0.68) were positively correlated with the final histologic score. Prednisone did not appear to have a protective effect on histologic score. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, liver enzyme activities, particularly ALT and ALP activities, should be closely monitored during lomustine treatment and acute increases in those activities may warrant discontinuation of lomustine to mitigate liver injury. Nonspecific ultrasonographic findings and abnormal increases in liver function tests were not detected until the onset of clinical liver failure. Glutathione depletion may have a role in lomustine-induced hepatopathy and warrants further investigation.

Genetic and environmental risk for lymphoma in boxer dogs.

BACKGROUND: Non-Hodgkin lymphoma in humans is associated with environmental chemical exposures, and risk is enhanced by genetic variants in glutathione S-transferases (GST) enzymes. OBJECTIVE: We hypothesized that boxer dogs, a breed at risk for lymphoma, would have a higher prevalence of GST variants with predicted low activity, and greater accumulated DNA damage, compared to other breeds. We also hypothesized that lymphoma in boxers would be associated with specific environmental exposures and a higher prevalence of canine GST variants. ANIMALS: Fifty-four healthy boxers and 56 age-matched nonboxer controls; 63 boxers with lymphoma and 89 unaffected boxers ≥10 years old. METHODS: We resequenced variant loci in canine GSTT1, GSTT5, GSTM1, and GSTP1 and compared endogenous DNA damage in peripheral leukocytes of boxers and nonboxers using the comet assay. We also compared GST variants and questionnaire-based environmental exposures in boxers with and without lymphoma. RESULTS: Endogenous DNA damage did not differ between boxers and nonboxers. Boxers with lymphoma were more likely to live within 10 miles of a nuclear power plant and within 2 miles of a chemical supplier or crematorium. Lymphoma risk was not modulated by known canine GST variants. CONCLUSIONS AND CLINICAL IMPORTANCE: Proximity to nuclear power plants, chemical suppliers, and crematoria were significant risk factors for lymphoma in this population of boxers. These results support the hypothesis that aggregate exposures to environmental chemicals and industrial waste may contribute to lymphoma risk in dogs.

Glutathione S-transferase theta genotypes and environmental exposures in the risk of canine transitional cell carcinoma.

INTRODUCTION: Transitional cell carcinoma (TCC) in humans is associated with environmental exposures and variants in glutathione S-transferase (GST) genes. Scottish Terriers have a high breed risk for TCC, but the relationship between genetic and environmental risk in dogs is not fully understood. HYPOTHESES: Scottish Terriers have a higher frequency of GST-theta variants compared to lower risk breeds. Dogs with TCC of any breed have a higher frequency of GST-theta variants along with higher environmental exposures, compared to controls. ANIMALS: One hundred and five Scottish Terriers and 68 controls from lower risk breeds; 69 dogs of various breeds with TCC, and 72 breed- and sex-matched unaffected geriatric dogs. METHODS: In this prospective case-control study, dogs were genotyped for 3 canine GST-theta variants: GSTT1 I2+28 G>A, a GSTT1 3'UTR haplotype, and GSTT5 Asp129_Gln130del. Owners of dogs with TCC and unaffected geriatric controls completed a household environmental questionnaire. RESULTS: The GSTT1 3'UTR haplotype and GSTT5 Asp129_Gln130del variants were significantly underrepresented in Scottish Terriers (minor allele frequency [MAF] = 0.000 for both), compared to dogs from lower risk breeds (MAF = 0.108 and 0.100; P ≤ .0002). Dogs with TCC did not differ from unaffected geriatric controls across the 3 investigated loci. Transitional cell carcinoma was associated with household insecticide use (odds ratio [OR] = 4.28, 95% confidence interval [CI] = 1.44-12.33, P = .02), and was negatively associated with proximity to a farm (OR = 0.49, 95% CI = 0.25-0.99, P = .04). CONCLUSIONS AND CLINICAL IMPORTANCE: Low-activity GST-theta loci are unlikely contributors to TCC risk in dogs. Increased risk is associated with household insecticide use, and possibly with less rural households.

Prospective crossover clinical trial comparing transdermal with oral phenobarbital administration in epileptic cats.

OBJECTIVES: The aim of this study was to compare serum phenobarbital concentrations, adverse events and client satisfaction during 14 weeks of transdermal vs oral phenobarbital administration to epileptic cats. METHODS: This was a prospective, fixed-order, crossover pilot study. Nine client-owned cats with presumptive or diagnosed idiopathic epilepsy were enrolled. Oral phenobarbital (PO-PB) was administered for weeks 1-14 (median starting dosage of 3.8 mg/kg [2.0-5.4 mg/kg/day] q12h); transdermal phenobarbital (TD-PB) was administered for weeks 14-28 (median starting dosage 18.8 mg/kg/day [17.6-24.0 mg/kg/day] q12h). Serum phenobarbital concentrations (S-PB) were measured at weeks 2, 14, 16 and 28. Client satisfaction questionnaires and biochemistry were evaluated at 14 and 28 weeks. RESULTS: Median S-PB concentrations during oral administration were 21 µg/ml (observed range 11-40 µg/ml) at week 2 and 22 µg/ml (8-35 µg/ml) at week 14, and at the higher TD dosage were 18 µg/ml (0-42 µg/ml) at week 16 and 17 µg/ml (7-50 µg/ml) at week 28. Phenobarbital concentrations were significantly correlated with PO dosage at week 2 (r = 0.75, P = 0.03) but not at weeks 16 and 28. Significantly more dose adjustments were needed during the TD phase (P = 0.03), but 6/9 owners (67%) still preferred TD to PO administration. Adverse effects were mild and comparable in both groups. CONCLUSIONS AND RELEVANCE: Therapeutic S-PB concentrations were achievable in some cats using TD-PB at 18 mg/kg/day q12h. Poor correlation between TD dosage and S-PB concentrations was observed and more dosage adjustments were required during TD administration. These findings necessitate close therapeutic drug monitoring if TD-PB is prescribed.

RNA expression profiling in sulfamethoxazole-treated patients with a range of in vitro lymphocyte cytotoxicity phenotypes.

The lymphocyte toxicity assay (LTA) is a proposed surrogate marker of sulfonamide antibiotic hypersensitivity. In the LTA, peripheral blood mononuclear cells (PBMCs) undergo apoptosis more readily in hypersensitive versus tolerant patients when exposed to drug-hydroxylamine metabolites in vitro. The purpose of this study was to identify key gene transcripts associated with increased cytotoxicity from sulfamethoxazole-hydroxylamine in human PBMCs in the LTA. The LTA was performed on PBMCs of 10 patients hypersensitive to trimethoprim-sulfamethoxazole (HS) and 10 drug-tolerant controls (TOL), using two cytotoxicity assays: YO-PRO (n = 20) and MTT (n = 12). mRNA expression profiles of PBMCs, enriched for CD8+ T cells, were compared between HS and TOL patients. Transcript expression was interrogated for correlation with % cytotoxicity from YO-PRO and MTT assays. Correlated transcripts of interest were validated by qPCR. LTA results were not significantly different between HS and TOL patients, and no transcripts were found to be differentially expressed between the two groups. 96 transcripts were correlated with cytotoxicity by YO-PRO (r = ±.63-.75, FDR 0.188). Transcripts were selected for validation based on mechanistic plausibility and three were significantly over-expressed by qPCR in high cytotoxicity patients: multi-specific organic anion transporter C (ABCC5), mitoferrin-1 (SLC25A37), and Porimin (TMEM123). These data identify novel transcripts that could contribute to sulfonamide-hydroxylamine induced cytotoxicity. These include SLC25A37, encoding a mitochondrial iron transporter, ABCC5, encoding an arylamine drug transporter, and TMEM123, encoding a transmembrane protein that mediates cell death.

Evaluation of potential serum biomarkers of hepatic fibrosis and necroinflammatory activity in dogs with liver disease.

BACKGROUND: Serum interleukin 6 (IL-6), chemokine ligand 2 (CCL2), C-reactive protein (CRP), and the ratio of aspartate transaminase to alanine transaminase (AST:ALT) have been correlated with fibrosis and necroinflammatory activity in humans with various hepatopathies. HYPOTHESIS/OBJECTIVES: To determine whether increases in serum IL-6, CCL2, CRP, or AST:ALT were associated with moderate to severe fibrosis or necroinflammatory activity in dogs with various hepatopathies. ANIMALS: Forty-four client-owned dogs with clinical evidence of liver disease and 10 healthy purpose-bred dogs, all undergoing liver biopsies by laparoscopy or laparotomy. METHODS: Measurement of serum IL-6, CCL2, CRP, AST, and ALT before scheduled liver biopsy and evaluation of liver histopathology using the METAVIR scoring system used in human medicine, blinded to clinical presentation. RESULTS: Median serum IL-6 was approximately twice as high in dogs with high fibrosis scores (15.5 pg/mL; range, 1.4 to 235 pg/mL) compared to dogs with low fibrosis scores (7.6 pg/mL; range, 1.4 to 148.1 pg/mL), with marginal significance (P = .05). Median serum CCL2 was significantly higher in dogs with active necroinflammation (444 pg/mL; range, 144 to 896 pg/mL) compared to dogs without detectable necroinflammation (326 pg/mL; range, 59 to 1692 pg/mL; P = .008), but with considerable overlap between groups. Neither serum CRP nor AST:ALT ratios were significantly different based on fibrosis or necroinflammatory scores. CONCLUSIONS AND CLINICAL IMPORTANCE: Because of substantial variability among dogs, single measurements of IL-6 and CCL2 have limited diagnostic utility for identifying fibrosis or necroinflammation, respectively, in dogs with various chronic liver diseases. The value of these biomarkers should be explored further in monitoring response to treatment in individual dogs with chronic hepatopathies.

Hepatic expression profiles in retroviral infection: relevance to drug hypersensitivity risk.

HIV-infected patients show a markedly increased risk of delayed hypersensitivity (HS) reactions to potentiated sulfonamide antibiotics (trimethoprim/sulfamethoxazole or TMP/SMX). Some studies have suggested altered SMX biotransformation in HIV infection, but hepatic biotransformation pathways have not been evaluated directly. Systemic lupus erythematosus (SLE) is another chronic inflammatory disease with a higher incidence of sulfonamide HS, but it is unclear whether retroviral infection and SLE share risk factors for drug HS. We hypothesized that retroviral infection would lead to dysregulation of hepatic pathways of SMX biotransformation, as well as pathway alterations in common with SLE that could contribute to drug HS risk. We characterized hepatic expression profiles and enzymatic activities in an SIV-infected macaque model of retroviral infection, and found no evidence for dysregulation of sulfonamide drug biotransformation pathways. Specifically, NAT1,NAT2,CYP2C8,CYP2C9,CYB5R3,MARC1/2, and glutathione-related genes (GCLC,GCLM,GSS,GSTM1, and GSTP1) were not differentially expressed in drug naïve SIVmac239-infected male macaques compared to age-matched controls, and activities for SMX N-acetylation and SMX hydroxylamine reduction were not different. However, multiple genes that are reportedly over-expressed in SLE patients were also up-regulated in retroviral infection, to include enhanced immunoproteasomal processing and presentation of antigens as well as up-regulation of gene clusters that may be permissive to autoimmunity. These findings support the hypothesis that pathways downstream from drug biotransformation may be primarily important in drug HS risk in HIV infection.

Immunogenicity of trimethoprim/sulfamethoxazole in a macaque model of HIV infection.

BACKGROUND: Sulfonamide hypersensitivity has a high incidence in HIV infection and correlates with low CD4+ counts, but the mechanisms are not understood. The aims of this study were to determine whether trimethoprim/sulfamethoxazole (TMP/SMX) led to SMX adduct formation, immunogenicity, or signs of drug hypersensitivity in SIV-infected rhesus macaques, and whether differences in antioxidants, pro-inflammatory mediators, or SMX disposition were predictive of drug immunogenicity. METHODS: Nine macaques chronically infected with SIVmac239 and 7 non-infected controls were studied. Baseline blood ascorbate, glutathione, IFN-γ, LPS, sCD14, and cytochrome b5 reductase measurements were obtained, macaques were dosed with TMP/SMX (120mg/kg/day p.o. for 14days), and SMX metabolites, lymph node drug adducts, drug-responsive T cells, and anti-SMX antibodies were measured. RESULTS: Four of 9 of SIV-positive (44%), and 3 of 7 SIV negative (43%) macaques had drug-responsive T cells or antibodies to SMX. Two macaques developed facial or truncal rash; these animals had the highest levels of lymph node drug adducts. Antioxidants, pro-inflammatory mediators, and SMX metabolites were not predictive of drug immunogenicity; however, the Mamu DRB1*0401/0406/0411 genotype was significantly over-represented in immune responders. CONCLUSIONS: Unlike other animal models, macaques develop an immune response, and possible rash, in response to therapeutic dosages of TMP/SMX. Studying more animals with CD4+ counts <200cells/µl, along with moderately restricted ascorbate intake to match deficiencies seen in humans, may better model the risk of SMX hypersensitivity in HIV-infection. In addition, the role of Mamu-DRB1 genotype in modeling drug hypersensitivity in retroviral infection deserves further study.

Genome-Wide Association Study in Immunocompetent Patients with Delayed Hypersensitivity to Sulfonamide Antimicrobials.

BACKGROUND: Hypersensitivity (HS) reactions to sulfonamide antibiotics occur uncommonly, but with potentially severe clinical manifestations. A familial predisposition to sulfonamide HS is suspected, but robust predictive genetic risk factors have yet to be identified. Strongly linked genetic polymorphisms have been used clinically as screening tests for other HS reactions prior to administration of high-risk drugs. OBJECTIVE: The purpose of this study was to evaluate for genetic risk of sulfonamide HS in the immunocompetent population using genome-wide association. METHODS: Ninety-one patients with symptoms after trimethoprim-sulfamethoxazole (TMP-SMX) attributable to "probable" drug HS based on medical record review and the Naranjo Adverse Drug Reaction Probability Scale, and 184 age- and sex-matched patients who tolerated a therapeutic course of TMP-SMX, were included in a genome-wide association study using both common and rare variant techniques. Additionally, two subgroups of HS patients with a more refined clinical phenotype (fever and rash; or fever, rash and eosinophilia) were evaluated separately. RESULTS: For the full dataset, no single nucleotide polymorphisms were suggestive of or reached genome-wide significance in the common variant analysis, nor was any genetic locus significant in the rare variant analysis. A single, possible gene locus association (COL12A1) was identified in the rare variant analysis for patients with both fever and rash, but the sample size was very small in this subgroup (n = 16), and this may be a false positive finding. No other significant associations were found for the subgroups. CONCLUSIONS: No convincing genetic risk factors for sulfonamide HS were identified in this population. These negative findings may be due to challenges in accurately confirming the phenotype in exanthematous drug eruptions, or to unidentified gene-environment interactions influencing sulfonamide HS.

Transient cold agglutinins associated with Mycoplasma cynos pneumonia in a dog.

This report details a case of reversible cold agglutinins in a dog with Mycoplasma cynos pneumonia. An 11-month-old female spayed Rhodesian Ridgeback was presented for lethargy and cough. Thoracic radiographs revealed an alveolar pattern present bilaterally in the cranioventral lung lobes. Septic neutrophilic inflammation with suspected Mycoplasma sp. organisms was noted on cytologic examination of a trans-tracheal wash, and the dog was treated empirically with IV ampicillin/sulbactam and enrofloxacin pending culture results. Red blood cell agglutination was noted unexpectedly on several blood film reviews during hospitalization; however, the dog never developed clinical or laboratory evidence of hemolysis. Cold agglutinins were demonstrated based on the results of a saline dilution and cold agglutinin test that showed agglutination at 4°C but not at room temperature (21°C) or 37°C. Based on a positive culture for M cynos, the dog was treated for 8 weeks with oral enrofloxacin. After clinical and radiographic resolution of the pneumonia, repeated saline dilution and cold agglutinin tests of peripheral blood were negative at all temperatures. Reversible, asymptomatic cold agglutinins are common in human patients with mycoplasma pneumonia, but this is the first reported case in a dog.

Report from the National Institute of Allergy and Infectious Diseases workshop on drug allergy.

Allergic reactions to drugs are a serious public health concern. In 2013, the Division of Allergy, Immunology, and Transplantation of the National Institute of Allergy and Infectious Diseases sponsored a workshop on drug allergy. International experts in the field of drug allergy with backgrounds in allergy, immunology, infectious diseases, dermatology, clinical pharmacology, and pharmacogenomics discussed the current state of drug allergy research. These experts were joined by representatives from several National Institutes of Health institutes and the US Food and Drug Administration. The participants identified important advances that make new research directions feasible and made suggestions for research priorities and for development of infrastructure to advance our knowledge of the mechanisms, diagnosis, management, and prevention of drug allergy. The workshop summary and recommendations are presented herein.

Therapeutic serum phenobarbital concentrations obtained using chronic transdermal administration of phenobarbital in healthy cats.

Seizures are a common cause of neurologic disease, and phenobarbital (PB) is the most commonly used antiepileptic drug. Chronic oral dosing can be challenging for cat owners, leading to poor compliance. The purpose of this study was to determine if the transdermal administration of PB could achieve serum PB concentrations of between 15 and 45 µg/ml in healthy cats. Nineteen healthy cats were enrolled in three groups. Transdermal PB in pluronic lecithin organogel (PLO) was applied to the pinnae for 14 days at a dosage of 3 mg/kg q12h in group 1 (n = 6 cats) and 9 mg/kg q12h in group 2 (n = 7 cats). Transdermal PB in Lipoderm Activemax was similarly applied at 9 mg/kg q12h for 14 days in group 3 (n = 6 cats). Steady-state serum PB concentrations were measured at trough, and at 2, 4 and 6 h after the morning dose on day 15. In group 1, median concentrations ranged from 6.0-7.5 µg/ml throughout the day (observed range 0-11 µg/ml). Group 2 median concentrations were 26.0 µg/ml (observed range 18.0-37.0 µg/ml). For group 3, median concentrations ranged from 15.0-17.0 µg/ml throughout the day (range 5-29 µg/ml). Side effects were mild. One cat was withdrawn from group 2 owing to ataxia and sedation. These results show therapeutic serum PB concentrations can be achieved in cats following chronic transdermal administration of PB in PLO at a dosage of 9 mg/kg q12h. More individual variation was noted using Lipoderm Activemax. Transdermal administration may be an alternative for cats that are difficult to medicate orally.