Dogs with HIV?

[Todd Miller - Pharmacology]

I wonder what the basis of the following observations are.  Obviously,
there is some kind of (non-specific?) cross reaction, but...

Unique Identifier
  90352614
Authors
  Strandstrom HV.  Higgins JR.  Mossie K.  Theilen GH.
Institution
  College of Veterinary Medicine, Helsinki, Finland.
Title
  Studies with canine sera that contain antibodies which recognize human
  immunodeficiency virus structural proteins.
Source
  Cancer Research.  50(17 Suppl):5628S-5630S, 1990 Sep 1.
Abstract
  In a serological survey, using the immunoblotting technique, we found that
  substantial numbers of dog sera from both normal and diseased dogs,
  including dogs with neoplasia, reacted with one or more human
  immunodeficiency virus (HIV) recombinant proteins. A total of 144 dog sera
  were tested, and 72 (50%) of them reacted with one or more HIV recombinant
  structural proteins. Ten dog sera were also tested for reactivity with
  simian immunodeficiency virus (SIV), feline immunodeficiency virus (FIV),
  and caprine arthritis encephalitis virus (CAEV). Six dog sera reacted with
  at least the major core protein of HIV, while one of the dog sera tested
  reacted with SIV core protein, and there were no reactions with the viral
  proteins of either FIV or CAEV. Cell extracts from canine peripheral blood
  lymphocytes cocultivated with human cells and an extract of human cells
  infected with HIV were immunoblotted against dog sera which previously
  tested positive or negative on HIV recombinant protein commercially
  available Western blot strips. Two lymphocyte lysates and the HIV-infected
  Hut cell lysate reacted with the Western blot strip-positive dog serum;
  however, no reactions were seen with the Western blot strip-negative dog
  serum.