Cost effect parasite treatments for use at a feral cat spay and neuter camp.


I am a vet and I work with a small animal welfare group in Athens (Greece) that spays feral cats. I wonder if you have any good suggestion for anti-parasitic treatments. I usually put a spot on of selamectin before the surgery to cure both ecto and endo parasites but it is quite expensive for large scale spaying projects. We are mainly working with feral cats that we trap, so there is no possibility to touch them after of before anesthesia. Thank you very much!

Answer Date: 
January 11, 2012

As you know selamectin is great option for treating both ecto and endo parasites but that, as you have mentioned, it is expensive.  One option is to split the large dog size spot on of Revolution (selemection) into smaller doses to use on multiple animals.  This practice is off-label, but is acceptable as long as it is done under the direction or supervision of a veterinarian.  This is an attractive option for shelters, as well as welfare groups, as it is cost-saving and may allow shelters to treat large numbers of animals with products that would otherwise be unaffordable.
The large dog size Revolution is 120 mg/mL and is 3 mL in size.  With the recommended dose of 6 mg/kg, you could treat 12 5kg cats with 0.25 mL each.  You could treat even more cats if they are smaller (for example a 3 kg cat would get 0.15 mL).  This product is labeled for cats 8 weeks of age and older but could be used on younger animals, realizing that it is off label.
Another product that would give similar coverage to Revolution is Advantage Multi (imidacloprid + moxidectin) for cats.  However, in the United States splitting doses of Advantage is actually illegal.  This is because Advantage is considered apesticide rather than a medication and, as such, is regulated by the Environmental Protection Agency (EPA) rather than the Food & Drug Administration (FDA). Unlike the FDA, the EPA does not allow for use of products in any manner other than exactly as product label describes.
Another idea is that since the ecto parasite coverage is short lived with these products, one option would be to treat endoparasites (as well as ear mites) with Ivermectin.  Ivermectin should help and although less expensive, may not be as effective as FDA-approved de-wormers.  Since it is formulated for use in cattle, doses for cats must be carefully calculated and should not be used in cats < 4 weeks old.  Ivermectin can be given SQ at 200mcg/kg – following is a helpful dosing chart.

Dose volumes are for undiluted 1% ivermectin:

                                                       Cat’s weight                 Dose SQ*                           

                                                        less than 5 lbs                 0.05 mL

                                                          5-7 lbs                           0.1 mL

                                                          8-10 lbs                         0.15mL

                                                         11-14 lbs                        0.2 mL

                                                         15-20 lbs                        0.25 mL

* Ideally treatment is repeated in Three weeks

More information on parasite control guidelines for animal shelters can be found on our  Parasite Control Guidelines for Animal Shelters information page

We hope this is helpful and thank you for taking such great cat of the feral cats in Greece!
Cynthia Karsten, DVM
Resident, Koret Shelter Medicine Program
Center for Companion Animal Health
UC Davis School of Veterinary Medicine