No abstract

Sera from dogs naturally infected with Leishmania infantum were analysed for the IgG subclass specificity of their antibody response by ELISA. Dogs infected with L. infantum produced both IgG1 and IgG2 antibodies with IgG2 being associated with asymptomatic infections and IgG1 being associated with disease (symptomatic dogs, non- or low-responsive to chemotherapy). The differential responses of IgG1 and IgG2 serum antibodies in asymptomatic and symptomatic dogs may indicate a dichotomous immune response to infection with L. infantum. To confirm this, on a broader scale, sera from dogs naturally exposed to an asymptomatic protozoan infection, Toxoplasma gondii, were also analysed as were sera from dogs exposed to the helminths, Dirofilaria immitis and Toxocara canis. Antibodies specific for T. gondii antigen detected in sera from 17 dogs were of the IgG2 subclass only. Both IgG1 and IgG2 antibodies to D. immitis and T. canis were present in the sera of naturally infected dogs but IgG1 appeared to be the predominant subclass. Furthermore, in dogs experimentally infected with T. canis, selective regulation of IgG2 and IgG1 responses was apparent since production of the two subclasses occurred at different times following infection, with IgG2 levels declining as IgG1 levels rose. Thus, the analysis of IgG subsets in parasitized dogs provides evidence of a dichotomous response to infection: IgG2 is associated with asymptomatic protozoan infections and IgG1 is associated with helminth infections and disease caused by protozoan infection.

Nutritional secondary hyperparathyroidism (NSH) was diagnosed in six cats during a three-year period, based on clinical, radiographic and laboratory findings. Clinical signs were attributable to severe osteopenia (n = 5) and hypocalcaemia (n = 4), which had resulted in spontaneous fractures of long bones, scapulae, pelvis, nasal bones, or spine, and in excitation, muscle twitching or seizures, respectively. Serum parathormone levels were markedly elevated, and 1,25(OH)2-vitamin D3 mildly elevated, whereas 25(OH)-vitamin D3 was mildly decreased compared to age-matched healthy cats. Treatment was limited to short-term parenteral calcium gluconate injections, as clinically indicated, a balanced diet and cage rest, which resulted in quick clinical recovery in four cases. The remaining two cats had to be euthanased because of progressive neurological deficits secondary to spinal fractures. At the time of writing, a multitude of commercial balanced diets is widely available and diseases secondary to dietary deficiencies have become rare. Nevertheless, NSH is still an important clinical entity, and should be considered in growing cats presenting with spontaneous fractures or seizures.

It may be concluded that the specificity of FTLV antibody found by e. g. IF or ELISA can be validated using Western blotting; the conspicuous signals at the 24k and 15k positions provide the definite proof. Although cross reactions appear to exist with e. g. the transmembrane protein of FeLV these are unidirectional and d o not affect the reliability of the methods.