IIRC, it's 15mg per cat (from memory).

(Checking). No, apparently it's 45mg:
http://www.revolution4dogs.com/PAHimages/compliance_pdfs/US_EN_RV_compliance.pdf

Concentrations of selamectin are greater in the large dog doses so
obviously you'll need to take that into a/c when splitting the dose.

Steve.

You have 38 pounds of cat to treat at a minimum of 2.7 mg per pound
so you need the size containing at least 103 mg of drug. That's going
to be the red box.  Give the 15 pound cat .35 ml, the 9 pounder .25
and the smaller cats .2 ml.  

Actual figures:

 minimum dose 2.7 mg per lb / 120mg per ml x 15 lb cat = .34 ml
 minimum dose 2.7 mg per lb / 120mg per ml x  9 lb cat = .20 ml
 minimum dose 2.7 mg per lb / 120mg per ml x  7 lb cat = .16 ml  
   
Weight(lb) Package  mg per tube   Potency(mg/mL)  volume (mL)
          color  

20.1-40    Red       120 mg           120           1.0
40.1-85    Teal      240 mg           120           2.0
85.1-130   Plum      120+240 mg       120           3.0



Revolution™ -- U.S. Prescribing Information

              Topical Parasiticide For Dogs and Cats

         
DESCRIPTION:
Revolution (selamectin) Topical Parasiticide is available as a
colorless to yellow,ready to use solution in single dose tubes for
topical(dermal) treatment of dogs and cats six weeks of age and
older. The content of each tube is formulated to provide a minimum of
2.7 mg/lb (6 mg/kg) of body weight of selamectin. The chemical
composition of selamectin is (5Z,25S)-25-cyclohexyl-
4'-O-de(2,6-dideoxy-3-O-methyl-a-L-arabino-hexopyranosyl)-5-demethoxy-
25-de(1-methylpropyl)-22,23-dihydro-5-hydroxyiminoavermectin A1a.

INDICATIONS:
Revolution kills adult fleas and prevents flea eggs from hatching for
one month and is indicated for the prevention and control of flea
infestations (Ctenocephalides felis), prevention of heartworm
disease caused by Dirofilaria immitis, and the treatment and control
of ear mite(Otodectes cynotis) infestations in dogs and cats.
Revolution also is indicated for the treatment and control of
sarcoptic mange (Sarcoptes scabiei) and for the control of tick
(Dermacentor variabilis) infestations in dogs, and the treatment of
intestinal hookworm (Ancylostoma tubaeforme) and roundworm
(Toxocara cati) infections in cats. Revolution is recommended for use
in dogs and cats six weeks of age and older.


DOSAGE:
The recommended minimum dose is 2.7 mg selamectin per pound (6 mg/kg)
of body weight.

BarB