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In both dogs and cats, routine haematology, biochemistry and urinalysis should be performed. Most parameters are usually within normal limits, but an anaemia can often be seen. Eosinophilia and basophilia are also common, and when seen together suggests occult dirofilariasis or allergic lung disease <sup>1, 3</sup>. Eosinophilia peaks as L5 enter the pulmonary arteries and subsequently varies. An inflammatory leukogram is also possible<sup>3</sup>. Hyperglobulinemia due to antigenic stimulation is an inconsistent finding<sup>1, 3</sup>. Right-sided heart failure or immune-complex glomerulonephritis can lead to hypoalbuminaemia and, very occasionally, nephrotic syndrome<sup>1</sup>. Because of this, it is possible for urinalysis to reveal proteiunuria<sup>1, 3</sup>. Haemoglobinaemia and haemoglobinuria are associated with caval syndrome<sup>3</sup>.
In both dogs and cats, routine haematology, biochemistry and urinalysis should be performed. Most parameters are usually within normal limits, but an anaemia can often be seen. Eosinophilia and basophilia are also common, and when seen together suggests occult dirofilariasis or allergic lung disease <sup>1, 3</sup>. Eosinophilia peaks as L5 enter the pulmonary arteries and subsequently varies. An inflammatory leukogram is also possible<sup>3</sup>. Hyperglobulinemia due to antigenic stimulation is an inconsistent finding<sup>1, 3</sup>. Right-sided heart failure or immune-complex glomerulonephritis can lead to hypoalbuminaemia and, very occasionally, nephrotic syndrome<sup>1</sup>. Because of this, it is possible for urinalysis to reveal proteiunuria<sup>1, 3</sup>. Haemoglobinaemia and haemoglobinuria are associated with caval syndrome<sup>3</sup>.
There are several methods for the specific demonstration of ''Dirofilaria immitis'' in the animal. Firstly, direct microscopic examination allows rapid identification microfilariae in a drop of fresh blood as their movements can vigorously displace the surrounding red blood cells<sup>2</sup>. Despite being quick, simple and inexpensive, this test is not sufficiently sensitive to provide a definitive diagnosis, particularly when there is a low concentration of microfilariae in the bloodstream. Filtration methods therefore exist to facilitate the microscopic demonstration of microfilariae. These include the modified Knott's test, which involves haemolysis, centrifugation and staining with methylene blue before direct examination. Tests such as this are more
sensitive than merely examining a drop of blood, and the morphology of microfilariae can be clearly seen. However, cats frequently lack circulating microfilariae, and so direct micrscopic examination is of little use in this species.
microscopic examination of a drop of fresh blood
blood cells. However, although this method offers an
microfilariae in the bloodstream. Filtration methods (eg,
and staining with methylene blue) are more
sensitive and allow morphological examination of the
microfilariae. In cats, given the absence or short-term
little practical value.
Antigen tests
Antigen tests
ELISA antigen tests detect specific circulating proteins
ELISA antigen tests detect specific circulating proteins
results because of the low antigen levels in the circulating
results because of the low antigen levels in the circulating
blood.
blood.
Antibody tests are currently available for routine screening
Antibody tests are currently available for routine screening
of feline heartworm infection, either as in-house or
of feline heartworm infection, either as in-house or
in unconventional hosts. However, at present, these tests
in unconventional hosts. However, at present, these tests
are not widely available.
are not widely available.
===Pathology===
===Pathology===