Small Animal Dermatology, 3rd edition

792 APPENDIX B DRUG FORMULARY

Drug name (trade orother names)

Pharmacology andindications

Adverse effects andprecautions

Dosing information andcomments

Formulations

Dosage (unlessotherwise indicated,dose is the same fordogs and cat)

Methimazole(Tapazole)

Antithyroid drug. Used fortreating hyperthyroidism,primarily in cats. Action isto serve as substrate forthyroid peroxidase anddecrease incorporation ofiodide into tyrosinemolecules.

In people, it has causedagranulocytosis andleukopenia. In cats,lupus-like reactions arepossible, such as vasculitisand bone marrowchanges. Well tolerated indogs.

Use in cats is based onexperimental studies inhyperthyroid cats.Methimazole has, for themost part, replacedpropylthiouracil for use incats. Adjust maintenancedose by monitoring T

4

levels. Twice-daily dosingin cats shown to be moreeffective than once-dailydosing.

5 and 10 mg tablets. Cat: 2.5 mg per cat q12h

po

×

7–14 days, then

5–10 mg per cat po q12h,and monitor T

4

concentrations.

Methocarbamol(Robaxin-V)

Skeletal muscle relaxant.Depresses polysynapticreflexes. Used fortreatment of skeletalmuscle spasms.

Causes some depressionand sedation of the CNS.

Results of clinical studiesin animals have not beenreported. Use in animals(and doses) based onexperience in people oranecdotal experience inanimals.

500, 750 mgtablets; 100 mg/mLinjection.

44 mg/kg q8h po on thefirst day, then22–44 mg/kg q8h po.