Comparison of 2 Doses for ACTH Stimulation Testing in Dogs Suspected of or Treated for Hyperadrenocorticism.

BACKGROUND: Lowering the cosyntropin dose needed for ACTH stimulation would make the test more economical. OBJECTIVES: To compare the cortisol response to 1 and 5 µg/kg cosyntropin IV in dogs being screened for hyperadrenocorticism (HAC) and in dogs receiving trilostane or mitotane for pituitary-dependent HAC. ANIMALS: Healthy dogs (n = 10); client-owned dogs suspected of having HAC (n = 39) or being treated for pituitary-dependent HAC with mitotane (n = 12) or trilostane (n = 15). PROCEDURES: In this prospective study, healthy dogs had consecutive ACTH stimulation tests to ensure 2 tests could be performed in sequence. For the first test, cosyntropin (1 µg/kg IV) was administered; the second test was initiated 4 hours after the start of the first (5 µg/kg cosyntropin IV). Dogs suspected of having HAC or being treated with mitotane were tested as the healthy dogs. Dogs receiving trilostane treatment were tested on consecutive days at the same time post pill using the low dose on day 1. RESULTS: In dogs being treated with mitotane or trilostane, the 2 doses were pharmacodynamically equivalent (90% confidence interval, 85.1-108.2%; P = 0.014). However, in dogs suspected of having HAC, the doses were not pharmacodynamically equivalent (90% confidence interval, 73.2-92.8%; P = 0.37); furthermore, in 23% of the dogs, clinical interpretation of test results was different between the doses. CONCLUSIONS AND CLINICAL RELEVANCE: For dogs suspected of having HAC, 5 µg/kg cosyntropin IV is still recommended for ACTH stimulation testing. For dogs receiving mitotane or trilostane treatment, a dose of 1 µg/kg cosyntropin IV can be used.

Neonatal aerosol exposure to Bermuda grass allergen prevents subsequent induction of experimental allergic feline asthma: evidence for establishing early immunologic tolerance.

Allergic asthma is increasing in industrialized countries, especially in children. Rodent and human studies suggest an opportunity to "prevent" asthma in the perinatal period. The aims of this study were to create a more "natural" model of feline asthma by exposing offspring of asthmatic queens to Bermuda grass allergen (BGA) by inhalation only, and to investigate maternal-fetal-infant interactions in the development of asthma. Kittens from asthmatic queens were divided into four groups: maternal exposure to aerosolized BGA during the third trimester, neonatal exposure to aerosolized BGA in the first three months of life, both maternal and neonatal exposure, or saline control. Kittens failing to achieve an asthmatic phenotype based on bronchoalveolar lavage fluid (BALF) analysis by 6 months underwent traditional sensitization: adjuvanted allergen injection, intranasal allergen, and aerosol challenges. BALF was collected at 3, 4 and 6 months, and after sensitization at 8 months, and analyzed for eosinophil counts and BGA-specific IgG and IgA. Intradermal testing (IDT) was performed at 6 and 7 months. At six months none of the kittens had airway eosinophilia, BGA-specific IgG or IgA, and were non-responsive to IDT. After sensitization, kittens receiving neonatal aerosolization failed to develop airway eosinophilia as seen in the controls. Kittens exposed to BGA aerosols, either in-utero or neonatally, continued to lack IDT response. Chronic exposure to BGA aerosols failed to induce asthma in kittens, and instead tolerized the kittens to BGA. This is the first evidence that neonatal intervention could potentially "prevent" allergic asthma in cats.

Endothelin-1 concentrations in bronchoalveolar lavage fluid of cats with experimentally induced asthma.

BACKGROUND: There is a need for biomarkers for diagnosis, therapeutic monitoring, and prognosis for asthma in cats. Endothelin-1 (ET-1) is implicated in the pathogenesis of inflammatory airway diseases in other species but not the cat. OBJECTIVE: To conduct a prospective experimental study to show that experimentally asthmatic cats, but not control cats without airway inflammation, would have increased concentrations of ET in BALF. ANIMALS: Eleven healthy, adult research cats. METHODS: Prospective experimental study. Six healthy cats without airway inflammation were used as controls. Asthma was induced using Bermuda grass allergen (BGA) in 5 cats. Collection of BALF for total nucleated cell and differential counts was performed. The concentration of ET-1 in cell-free BALF samples was determined. Data were analyzed using a Mann-Whitney U-test with P < .05 considered significant. RESULTS: The median [range] BALF total cell numbers, eosinophil numbers, and eosinophil percentages were significantly higher in the cats following experimental induction of asthma (1,870 cells/µL [1,450-3,440], 711 cells/µL [356-1,686] and 38% [20-49]) compared to baseline control parameters (462 cells/µL [239-780], 18 cells/µL [18-62] and 3.5% [0-8]) (P < .01). The median [range] BALF ET concentration was also significantly higher after induction of asthma (1.393 fmol/mL[0.977-2.247]) compared to healthy control cats (0.83250 fmol/mL [0.625-1.038]) (P = .012). CONCLUSIONS AND CLINICAL IMPORTANCE: This study suggests that BAL ET-1 concentration can be used to differentiate normal cats from those with experimentally induced asthma. If the same holds true for cats with naturally developing asthma, BAL ET-1 may prove a useful diagnostic biomarker for asthma.