I have made similar experiences - 2 out of my 4 dhs do have allergies during our very hot and dry summers ; they seem to be contact allergies , when the gras gets really dry ad prickly. I tried a whole lot of different things and for dh No1 all subsided once I found out , that she is also fairly allergic to " everything fish " - including fishoil , which I used to feed in summer , poor thing . Once I eliminated the foods she is allergic too , she doesn't show any signs of extra itchiness in summer any more . I do feed raw/homemade for the most part . I also do give homoeopathy during the summer ( Urtica and Sulfur in different potencies ) and I read in a few magazines/brochures that feeding raw , local honey in spring will help with allergies ( a bit like a nosode or vaccination , preparing the immunesystem for the onslaught) . Sometimes the dogs are just allergic to the grassmites that crawl up their legs - this will start showing in spring - a very easy " homerecipe " for this , given to me by a vet , can be to put flea/tick collars around their ankles ;they should also repell the grassmites . Which is fine for most breeds , but with dhs /sighthounds one has to be careful .
My 2nd girl has only mild allergies and also only when it is really hot and dry , once we get rain , she feels much better . She does get the homoeopathy and , currently ( as we are experiencing a drought ) 1 antihistamine/day ( vet recommended dosage for her : 2xdaily 3 pills ! ) . This is all she needs to stay happy. With her it is clearly not a grass mite allergy as she itches ay up the legs , where the seeds/heads of the dry grasses touch her - needless to say , I do stay on the paths when walkig in summer as to not encourage her to walk through the high stuff either.
One more note , the 2 are not realted , but the other 2 I have are closely related to one of each and do not show any signs of allergies ....
Verena