title: Clinical evaluation of a novel liquid formulation of L-thyroxine for once daily treatment of dogs with hypothyroidism.
abstract: BACKGROUND
  A liquid solution of levothyroxine (L-T4) is available for treatment of canine hypothyroidism.
  
  
  OBJECTIVE
  Once daily oral administration of a liquid L-T4 solution is effective and safe for controlling hypothyroidism in dogs.
  
  
  METHODS
  Thirty-five dogs with naturally occurring hypothyroidism.
  
  
  METHODS
  Dogs received L-T4 solution PO once daily at a starting dosage of 20 microg/kg body weight (BW). The dose was adjusted every 4 weeks, based on clinical signs and peak serum total T4 (tT4) concentrations. Target peak serum tT4 and thyroid stimulating hormone (TSH) concentrations, 4-6 hours posttreatment, were 35-95 nmol/L and < 0.68 ng/mL, respectively. Dogs were followed for up to 22 weeks after establishment of the maintenance dose.
  
  
  RESULTS
  Clinical signs of hypothyroidism improved or resolved in 91% of dogs after 4 weeks of L-T4 treatment at 20 microg/kg once daily. The maintenance dose was established in 76, 94, and 100% of dogs after 4, 8, and 12 weeks of treatment, respectively. This was 20 microg L-T4/kg BW for 79% of the dogs, 30 microg/kg BW for 15%, and 10-15 microg/kg BW in the remaining 6%, once daily. Thereafter, median peak tT4 and TSH concentrations were 51 nmol/L and 0.18 ng/mL, respectively, and remained stable during the 22-week follow-up; clinical signs did not recur.
  
  
  CONCLUSIONS
  All of the hypothyroid dogs had rapid clinical and hormonal responses to supplementation with the PO-administered L-T4 solution. The starting dosage of 20 microg L-T4/kg BW once daily was suitable for 79% of dogs.
authors.affiliation: Intervet/Schering-Plough Animal Health, Beaucouzé, France.
authors.forename: G
authors.initials: G
authors.lastname: Le Traon
authors.forename: S F
authors.initials: SF
authors.lastname: Brennan
authors.forename: S
authors.initials: S
authors.lastname: Burgaud
authors.forename: S
authors.initials: S
authors.lastname: Daminet
authors.forename: K
authors.initials: K
authors.lastname: Gommeren
authors.forename: L J I
authors.initials: LJ
authors.lastname: Horspool
authors.forename: D
authors.initials: D
authors.lastname: Rosenberg
authors.forename: C T
authors.initials: CT
authors.lastname: Mooney
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004304:Dosage Forms; D004305:Dose-Response Relationship, Drug; D007037:Hypothyroidism / Q000188:drug therapy / Q000662:veterinary*; D013974:Thyroxine / Q000008:administration & dosage* / Q000627:therapeutic use*
chemical_list: D004304:Dosage Forms; D013974:Thyroxine