Slentrol should be available “in the spring,” according to Pfizer Animal Health. The once-daily drug should cost between $1 and $2 a dose, a company spokeswoman told the Associated Press. Stephen Sundlof, director of Center of Veterinary Medicine at the FDA, called Slentrol “a welcome addition to animal therapies because dog obesity appears to be increasing.”Veterinarians generally define a dog that weighs 20 percent more than its ideal weight as obese. Surveys have found that approximately 5% of dogs in the US are obese and another 20-30% are overweight.