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fungal organism itself, concentration of fungal elements Molecular Testing
VetBooks.ir in the sample, sample integrity, culture requirements diagnosis of fungal diseases in tissues or body fluids in
Molecular testing is less commonly employed for the
of the fungal agent, and expertise of the laboratory
veterinary medicine as it is for bacterial, viral, and proto-
performing the culture.
Obtaining and submitting the appropriate sample zoal diseases. Molecular techniques are the same as
for culture and providing the laboratory with detailed reported for other infectious diseases and include con-
history and clinical diagnosis are essential for a success- ventional, nested, and real‐time PCR and sequencing.
ful culture. Samples of urine, exudates, and body cavity Common target genes are the 18S or 5.8S ribosomal gene
fluids can be submitted in sterile serum collection tubes. or internal transcribed spacer (ITS) regions of ribosomal
Up to 10 mL of fluid is recommended. Samples of fresh DNA. Fungal identification based on DNA sequencing is
tissue from a lesion can be submitted in a sterile con- not always definitive because results depend on whether
tainer for culture. or not the DNA of the fungus in question has been previ-
Identification of fungal agents in cultures is time‐ ously sequenced and submitted to the genomic data-
consuming. The culture has to grow and form charac- bases. Therefore, fungal identification based on DNA
teristic fruiting bodies, conidia, or arthrospores to sequencing should include at least two DNA regions for
allow morphologic identification of the fungus. comparison.
Microscopic morphology of fungal reproductive struc- In contrast, PCR‐based methods are commonly used
tures is the most useful criterion for identification. It is to confirm identification of fungi culture in diagnostic
strongly advised that fungal culture (other than for der- laboratories. Commercial chemiluminescent‐labeled
matophytosis) is performed in a reference diagnostic DNA probes are available for some fungal agents such as
laboratory. Blastomyces, Coccidioides, and Histoplasma.

Further Reading

Goldstein RE. Canine leptospirosis. Vet Clin North Am detection and differentiation of wild‐type and vaccine
Small Anim Pract 2010; 40: 1091–101. strains of canine distemper virus. Virol J 2010; 7: 86.
Schulz BS, Strauch C, Mueller RS, Eichhorn W, Hartmann Solano‐Gallego L, Baneth G. Diagnosis of protozoal and
K. Comparison of the prevalence of enteric viruses in arthropod‐borne diseases. In: Villiers E, Ristic J,
healthy dogs and those with acute haemorrhagic Blackwood L, eds. BSAVA Manual of Canine and Feline
diarrhoea by electron microscopy. J Small Anim Pract Clinical Pathology. Gloucester, UK: BSAVA, 2016.
2008; 49: 84–8. Solano‐Gallego L, Koutinas A, Miro G, et al. Directions for
Si W, Zhou S, Wang Z, Cui SJ. A multiplex reverse the diagnosis, clinical staging, treatment and prevention
transcription‐nested polymerase chain reaction for of canine leishmaniosis. Vet Parasitol 2009; 165: 1–18.