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this is that the prevalence of FIV in a low risk population approaches the expected frequency of false positives. So for each positive test result obtained in cats at low risk, there is a higher chance that the result is a false positive. Maternally-derived FIV antibodies may result
in positive serology in uninfected kittens. A positive serology results in a cat under 6 months of age can be confirmed with qPCR. Alternatively, serology can be repeated after 6 months of age. Negative serology in kittens is reliable. Where prior vaccination with Fel-O-Vax FIV is confirmed or cannot be ruled out, Anigen Rapid FIV/FeLV or Witness FeLV/FIV are useful screening
tests. A positive result using one of these kits can be confirmed with the other kit or with qPCR depending on availability and finances.
References
1. Levy JK, Crawford PC, Tucker SJ. Performance of 4 point-of-care screening tests for feline leukemia virus and feline immunodeficiency virus. J Vet Intern Med. 2017;31(2):521-6.
2. Westman ME, Malik R, Hall E, Harris M, Norris JM. The protective rate of the feline immunodeficiency virus vaccine: An Australian field study. Vaccine. 2016;34(39):4752-8.
3. Westman ME, Malik R, Hall E, Sheehy PA, Norris JM. Determining the feline immunodeficiency virus (FIV) status of FIV-vaccinated cats using point-of-care antibody kits. Comp Immunol Microbiol Infect Dis. 2015;42:43-52.
4. Crawford C. Does a Diva Test Exist for Differentiating FIV Infection From FIV Vaccination? J Vet Intern Med. 2016;30(4):1475-6.
5. Westman ME, Malik R, Hall E, Harris M, Hosie MJ, Norris JM. Duration of antibody response following vaccination against feline immunodeficiency virus. Journal of Feline Medicine and Surgery. 2016;0(0):1098612X16673292.
6. Lappin M. Detection of feline immunodeficiency virus antibodies in serum of vaccinated cats using a commercially available kit. Journal of veterinary internal medicine / American College of Veterinary Internal Medicine. 2015;29(4):1207.
WSV18-0092
ONCOLOGY
CURRENT TREATMENT OPTIONS FOR MAST CELL TUMORS IN DOGS AND CATS
C. Cannon1, S. Ryan1
1University of Melbourne, U-Vet Animal Hospital, Melbourne, Australia
CURRENT TREATMENT OPTIONS FOR MAST CELL TUMOURS IN DOGS AND CATS
Claire Cannon BVSc (hons) DACVIM (Oncology) MANZCVS
Stewart Ryan BVSc (hons) MS DACVS MANZCVS University of Melbourne U-Vet Animal Hospital claire.cannon@unimelb.edu.au stewart.ryan@unimelb.edu.au
Learning objectives: Understand the perioperative management, staging and surgical oncology principles for cutaneous MCT in dogs and cats, and the indications for adjunctive radiation therapy or chemotherapy in conjunction with surgery. Understand treatment options for non-resectable MCTs.
Canine cutaneous MCTs: Diagnosis:
· Cytology is usually diagnostic, and finding of suspected high grade MCT on cytology is highly predictive for histologic high grade.
Your Singapore, the Tropical Garden City
  7. Morton JM, McCoy RJ, Kann RKC, Gardner IA, Meers J. Validation of real-time polymerase chain reaction tests for diagnosing feline immunodeficiency virus infection in domestic cats using Bayesian latent class models. Prev Vet Med. 2011.
8. Pinches MDG, Diesel G, Helps CR, Tasker S, Egan K, Gruffydd-Jones TJ. An update on FIV and FeLV test performance using a Bayesian statistical approach. Veterinary Clinical Pathology. 2007;36(2):141-7.
9. Diehl LJ, Mathiasondubard CK, Onell LL, Hoover EA. Longitudinal assessment of feline immunodeficiency virus kinetics in plasma by use of a quantitative competitive reverse-transcriptase PCR. J Virol. 1995;69(4):2328-32.
· In my practice, complete staging involves evaluation of local/draining lymph nodes, abdominal ultrasound with liver and spleen cytology, and bone marrow evaluation. Bone marrow is typically reserved
for cases with CBC abnormalities because it is uncommon (< 5%).
· Lymph node (LN) evaluation is always recommended because low-grade MCT may metastasise. MCTs affecting the muzzle and perioral tissues may be more likely to metastasise. LN mapping is ideal to identify the ‘sentinel’ node. Diagnosis of metastasis from both cytology and histology can be challenging, but criteria have been recently published that may assist (1, 2). Good outcomes can be achieved with aggressive treatment in low grade, stage 2 MCT so identifying metastatic LN prior to surgery is important. Abdominal ultrasound and liver and spleen cytology is recommended in cases of known or suspected high grade tumours or when grade is unknown and local therapy is likely to be radical.
· Histology: The 2-tier histologic grading scheme (low/ high grade) has better inter-pathologist agreement than the 3-tier scheme, however combining the two may give additional information. Mitotic index (per 10 high power fields) is i prognostic, though the most useful value is not fully determined. The significance of additional prognostic factors (Ki67, AgNORs, c-kit staining pattern and mutation) is, in my opinion, not fully determined in terms of effect on prognosis.
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