Diagnostic Accuracy of a Point-of-Care Immunoassay for Feline Immunodeficiency Virus Antibodies, Feline Leukemia Virus Antigen, and Dirofilaria immitis Antigen.

Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are retroviral infections of cats worldwide whose clinical manifestations range from mild to severe disease. In both cases, infected cats can live a long life with proper care and should be managed to prevent infection of other cats. Dirofilaria immitis, the nematode that causes heartworm disease, can infect cats in any region where dogs are infected. Though cats are more resistant to infection, clinical diseases in the form of heartworm-associated respiratory disease can cause death. Screening for these infectious diseases enables veterinarians to manage their cases and prevent the spread to other cats. We describe the diagnostic accuracy of a point-of-care immunoassay for FIV, FeLV, and heartworm, compared to reference methods commonly available through reference laboratories to the practicing veterinarian. For FIV, we report 100% sensitivity (95% confidence limits (CL): 96.2-100%) and 97.8% specificity (95% CL: 95.4-99.4%). For FeLV, we report 100% sensitivity (95% CL: 97.7-100%) and 99.2% specificity (95% CL: 97.1-99.9%). And for heartworm, we report 90.2% sensitivity (95% CL: 76.9-97.3%) and 100% specificity (95% CL: 98.3-100%). Veterinarians may expect this performance relative to the reference methods they use for confirmatory serological testing.

Use of a Point-of-Care Progesterone Assay to Predict Onset of Parturition in the Bitch.

An assay of circulating progesterone (P4) is commonly used to estimate progress through late gestation in the bitch. Point-of-care assays provide rapid results, a major advantage over laboratory-based assays. This study aims to compare P4 levels determined by the Catalyst® Progesterone point-of-care assay with those determined by chemiluminescent immunoassay (CLIA) and to identify the expected distribution of Catalyst P4 levels at time intervals 3 days prior to the onset of parturition in pregnant bitches. Twenty-eight pregnant bitches carrying two or more fetuses were admitted to a specialist veterinary reproduction hospital 53 days after the onset of cytological diestrus or, when that date was not known, 57 days after the last mating. Vaginal speculum examinations were performed every 6 h until the onset of cervical dilatation (TCD). Serum samples were collected twice daily (08h00 and 18h00) until TCD. For most samples, fresh serum was assayed for P4 immediately using the Catalyst assay (CatP4), then frozen until assayed by CLIA (IMMULITE 2000; ImmP4). However, for some samples, CatP4 was not analyzed prior to freezing. For these data points (n = 33), CatP4 for fresh serum was estimated from CatP4 assayed on frozen-thawed serum, based on a comparison between CatP4 on fresh vs. frozen-thawed sera. In comparison to ImmP4, CatP4 levels up to and including 7 nmol/L appear to have a constant bias of -1.69 nmol/L (limits of agreement -4.91 to 1.52), while levels >7 nmol/L appear to have a proportional bias of -17.9% (limits of agreement -68.6% to 32.7%). Bootstrapped percentiles of CatP4 results spanned 0.4-9 nmol/L within 12 h of TCD, 0.9-11 nmol/L 12-24 h from TCD, and 2.2-13.5 nmol/L 24-36 h from TCD. A CatP4 >9 nmol/L indicates a bitch that is unlikely to reach TCD within 12 h. Bitches with CatP4s below 3.5 nmol/L are likely to reach TCD within 36 h and bitches with a CatP4 below 2.2 nmol/L are likely to reach TCD within 24 h. In conclusion, the Catalyst Progesterone assay provides rapid assessment of circulating P4 in the bitch, with clinical application in the monitoring of late term pregnant bitches.

feG-COOH blunts eosinophilic airway inflammation in a feline model of allergic asthma.

OBJECTIVE AND DESIGN: This study investigated if feG-COOH would decrease allergen-induced airway inflammation. MATERIALS OR SUBJECTS: Seven adult cats sensitised to Bermuda grass allergen (BGA) to induce an asthmatic phenotype. TREATMENT: Cats were randomized to receive either feG-COOH (1 mg/kg, PO) or placebo (saline 1 ml, PO) immediately prior to BGA aerosol challenge in a cross-over design. METHODS: Bronchoalveolar lavage fluid (BALF) was collected and airway inflammatory response assessed via inflammatory cell number and type; IL-4, IFN-gamma and nitric oxide metabolite concentrations. A paired t test was used to compare parameters with a P < 0.05 considered significant. RESULTS: The BALF eosinophil percentage was significantly lower in asthmatic cats treated with feG compared with placebo (placebo, 35.3 +/- 12.2%; feG, 22.4 +/- 8.6%; P = 0.002). Treatment with feG did not result in a significant change in any other parameter measured. CONCLUSIONS: These data indicate that a single dose of feG-COOH partially attenuates eosinophilic airway inflammation in experimental feline asthma.

Pharmacokinetics of cetirizine in healthy cats.

OBJECTIVE: To develop a high-performance liquid chromatography (HPLC) assay for cetirizine in feline plasma and determine the pharmacokinetics of cetirizine in healthy cats after oral administration of a single dose (5 mg) of cetirizine dihydrochloride. ANIMALS: 9 healthy cats. PROCEDURES: Heparinized blood samples were collected prior to and 0.5, 1, 2, 4, 6, 8, 10, and 24 hours after oral administration of 5 mg of cetirizine dihydrochloride to each cat (dosage range, 0.6 to 1.4 mg/kg). Plasma was harvested and analyzed by reverse-phase HPLC. Plasma concentrations of cetirizine were analyzed with a compartmental pharmacokinetic model. Protein binding was measured by ultrafiltration with a microcentrifugation system. RESULTS: No adverse effects were detected after drug administration in the cats. Mean +/- SD terminal half-life was 10.06 +/- 4.05 hours, and mean peak plasma concentration was 3.30 +/- 1.55 microg/mL. Mean volume of distribution and clearance (per fraction absorbed) were 0.24 +/- 0.09 L/kg and 0.30 +/- 0.09 mL/kg/min, respectively. Mean plasma concentrations were approximately 2.0 microg/mL or higher for 10 hours and were maintained at > 0.72 microg/mL for 24 hours. Protein binding was approximately 88%. CONCLUSIONS AND CLINICAL RELEVANCE: A single dose of cetirizine dihydrochloride (approx 1 mg/kg, which corresponded to approximately 0.87 mg of cetirizine base/kg) was administered orally to cats. It was tolerated well and maintained plasma concentrations higher than those considered effective in humans for 24 hours after dosing. The half-life of cetirizine in cats is compatible with once-daily dosing, and the extent of protein binding is high.

Adjuvanted rush immunotherapy using CpG oligodeoxynucleotides in experimental feline allergic asthma.

Allergic asthma is driven by relative overexpression of Th2 cell-derived cytokines in response to aeroallergens. In independent studies, both allergen-specific rush immunotherapy (RIT) and CpG oligodeoxynucleotides (ODN) showed promise in blunting eosinophilic inflammation in a model of feline allergic asthma. We hypothesized that RIT using allergen and CpG ODN would work synergistically to dampen the asthmatic phenotype in experimentally asthmatic cats. Twelve cats with asthma induced using Bermuda grass allergen (BGA) were studied. Of these, six were administered adjuvanted BGA RIT using CpG ODN #2142; six were administered placebo (saline) RIT and later crossed over to adjuvanted RIT. Over 2 days, subcutaneous CpG ODN (0.5ng/kg) with BGA (increasing doses every 2h from 20 to 200microg) was administered. Adverse events were recorded and compared with historical controls. Percentage of eosinophils in bronchoalveolar lavage fluid (BALF), % peripheral CD4+CD25+ T regulatory cells (Tregs), lymphocyte proliferation in response to ConA, and cytokine concentrations in BALF were measured over 2 months. Group mean BALF % eosinophils for the adjuvanted RIT cats were significantly lower at week 1 and month 1 (p=0.03 for both), and marginally significantly lower at month 2 (p=0.09) compared with placebo RIT cats. By the end of the study, 8/12 treated cats had BALF % eosinophils within the reference range for healthy cats. Adjuvanted RIT, but not placebo RIT, cats had significant decreases in the ConA stimulation index over time (p=0.05). BALF IL-4 concentrations were significantly higher at week 1 in adjuvanted RIT cats compared with baseline and month 2, and also with placebo RIT cats at week 1. No significant differences were detected between treatments or over time for IL-10 or IFN-gamma concentrations in BALF or for %Tregs cells in peripheral blood. Adjuvanted RIT using CpG ODN in experimental feline asthma dampens eosinophilic airway inflammation. Adverse effects associated with adjuvanted RIT were less severe compared with a historical, non-adjuvanted RIT protocol. The exact mechanism(s) by which adjuvanted RIT alters the aberrant allergic immune response were not elucidated in this study.

Effects of cyproheptadine and cetirizine on eosinophilic airway inflammation in cats with experimentally induced asthma.

OBJECTIVE: To determine whether oral administration of cyproheptadine or cetirizine blocks the action of serotonin and histamine, respectively, and results in diminished eosinophilic airway inflammation in cats with experimentally induced asthma. ANIMALS: 9 cats in which asthma was experimentally induced through exposure to Bermuda grass allergen (BGA) during a 3-month period. PROCEDURES: Cats were randomized to receive monotherapy with each of 3 treatments for 1 week: placebo (flour in a gelatin capsule, PO, q 12 h), cyproheptadine (8 mg, PO, q 12 h), or cetirizine (5 mg, PO, q 12 h). A 1-week washout period was allowed to elapse between treatments. Prior to and following each 1-week treatment period, blood and bronchoalveolar lavage fluid (BALF) samples were collected. The percentage of eosinophils in BALF was evaluated to determine treatment efficacy. Serum and BALF BGA-specific immunoglobulin contents and plasma and BALF histamine concentrations were determined via ELISAs. Plasma and BALF serotonin concentrations were measured by use of a fluorometric method. RESULTS: The mean +/- SD percentage of eosinophils in BALF did not differ significantly among treatment groups (placebo, 40 +/- 22%; cyproheptadine, 27 +/- 16%; and cetirizine, 31 +/- 20%). Among the treatment groups, BGA-specific immunoglobulin content and histamine and serotonin concentrations were not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: In cats with experimentally induced asthma, cyproheptadine and cetirizine were not effective in decreasing airway eosinophilic inflammation or in altering several other measured immunologic variables. Neither cyproheptadine nor cetirizine can be advocated as monotherapy for cats with allergen-induced asthma.