Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that you have been waiting for a response, but your requested expert isn't online which delayed your question coming up on the list for all to answer. I would like to help if you are still interested in an opinion. I understand that you are concerned about a rash Sawdust has on his belly and inner rear legs
Do your pup's lesions look like the ones in the links below?
This sounds very much like a surface pyoderma or skin infection. It may be secondary to an allergy or a surface wound that became infected. Certainly flea allergy could cause these types of lesions too.
If he isn't on any type of flea and tick control he should be this time of year. Frontline Plus, Advantix or the new Seresto flea and tick collar are excellent. Don't use over the counter products, especially Hartz or Sargents, as most are ineffective if not toxic
Other possible causes would be a fungal infection or, a demodex or sarcoptic mite infection.
I would recommend placing an Elizabethan collar to prevent licking
the area so he cannot further traumatize his skin.
You can also shave the involved area if there is a lot of hair in the area as that will allow it to dry out better.
In case this is an allergy related skin problem to relieve the itchy skin you can give:
1)Benadryl (diphenhydramine only don't use the combination products with acetaminophen or decongestants as they can be toxic to dogs) at 1mg to 2mg per pound of body weight or one 25mg capsule per 15-25 pounds of body weight orally every 8 hours. Dogs take a significantly higerh dose per pound of body weight than people do, so although this is a very high dose for a person, it isn't for a dog.
OR 2)Claritin (loratidine) at 5mg per 25 pound dog once or twice daily.
OR 3)Hydroxyzine at 1mg per pound orally every 8 hours.
OR 4) Chlorpheniramine at 4mg to 8mg per dog once or twice daily.
OR 5) Zyrtec (Cetirizine hydrochloride) at 1/2 mg per pound of body weight orally every 24 hours. That would be one 10mg tablet per 20 pounds of body weight. Make sure it is NOT the formulation with a decongestant (such as Zyrtec-D) because dogs cannot tolerate decongestants.
Some dogs do better on one antihistamine rather than another. You'll have to see which one works. Give whichever one you pick a week trial and if it isn't working try another. Be aware antihistamines can cause sleepiness or hyperactivity in some dogs. These side effects do wear off with repeated use.
Omega-3 fatty acids are fish oil products. 3V by DVM or Derm Caps ES are good brand name products. I recommend a dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give him 20mg of EPA per pound of body weight per day. For example a 70 pound dog could take 1400mg of EPA per day.
Use a solution mix of Betadine solution and warm water, made to look like weak tea, and clean the affected areas twice daily. This is an antibacterial and will dry the lesions out to allow them to heal. It does stain horribly though so you probably want to do this outside. Betadine solution is available over the counter at the drug store, if in doubt ask the pharmacist for help.
If he is no better in 4 to 5 days then he really must see a veterinarian for an examination, some diagnostic skin scrapings and probably some oral antibiotics.
Please let me know if you have any further questions.