What she recommends is to do injections IM there can be drawbacks on doing IM but to date have not had any problems with welts. Below is a description of the 3 ways to inject.
The IM injection is performed with similar needle angle and direction, but it is in the muscular tissue along and to the side of the dorsal fin (see Drawing 2). With a muscular injection, you must keep the needle in the muscle tissue and press the plunger as you with draw the needle giving room for the fluid to enter. Because of this, the needle must be inserted deeply.
What we recommend is to inject on one side and then move to the opposite side for next injection. Start toward backside and on each rotation move up a bit for the next injection. We have found by the 3rd or 4th injection along with topical treatment you can start to see improving results.
We found that by using a 30" Smart Koi Net that we had less stress and a much easier time holding and injecting Koi. You can leave Koi submersed in water without having to remove them to inject. You can also do the topical treatment at the same time and then release back to pond or QT.
We find it best to clean the open ulcer the first 2-3 days of injections, after that we just use the ointment and denture powder only without scrubbing wound. The reason we don't after the first few days is we do not want to destroy any tissue that is regenerating over ulcer. We use hydro peroxide with a cotton swab to clean and remove any dead tissue and clean under the layer of scales around wound. After doing that we apply Debride is a medicated ointment or Panalog from your vet.
Panolog (Only available through Vet) is a formulation that contains medications with anti-puritic, anti-bacterial, anti-fungal, anti-allergic and anti-inflammatory properties.The ointment provides relief against the symptoms of variety of ear and skin infections that are perilous for dogs and cats. We also use Tricide Neo® as topical powder for anti-bacterial to the open ulcer We then use denture powder to apply over ointment or Tricide-Neo to seal it it.
Until then "Happy Ponding" from "Koiman"