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Conundrums:
· Diagnosis: Unlikely canine nodal lymphoma, cytology alone is often insufficient for diagnosis
and histopathology is often required. IHC should
be pursued to assist in diagnosis, especially of Hodgkin’s-like lymphoma and in any equivocal cases. The histological designation ‘T cell rich
B cell lymphoma’ is used interchangeably with Hodgkin’s-like lymphoma by some pathologists, but the clinical presentation (single or regional lymph nodes, usually not disseminated disease) must be considered to diagnose Hodgkin’s-like lymphoma and choose appropriate treatment. I have seen
a case of a drug reaction in a cat with marked peripheral lymphadenopathy that was diagnosed as emerging large B cell lymphoma on H&E, however IHC showed reactive hyperplasia. The inciting
drug was discontinued with rapid resolution of lymphadenopathy.
· Treatment: In general, although data is lacking, nodal lymphoma in cats is treated as for dogs
i.e. depending on whether it is a large or small
cell variant. In the specific case of Hodgkin’s-like lymphoma, surgery is often pursued as an initial treatment, but whether or not chemotherapy should be used at all, as an adjuvant treatment, after progression, or instead of surgery is undefined.
References:
Vail DM, Withrow SJ, editors. Withrow and McEwen’s Small Animal Clinical Oncology (5th edition) W.B. Saunders, Philadelphia, 2012 is recommended as a general resource
1. Smith AL, Wilson AP, Hardie RJ, Krick EL, Schmiedt CW Perioperative complications after full-thickness gastrointestinal surgery in cats with alimentary lymphoma J Vet Surg 2011;40:849-852
2. Kiupel M, Smedley RC, Pfent C, Xie Y, Xue Y, Wise AG, DeVaul JM, Maes RK Diagnostic algorithm to differentiate lymphoma from inflammation in feline small intestinal biopsy samples Vet Pathol 2011;48:212-222
3. Nagata K, Lamb M, Goldschmidt MH, Duda L, Walton R. The usefulness of immunohistochemistry to differentiate between nasal carcinoma and lymphoma in cats: 140 cases (1986-2000) Vet Comp Oncol 2014;12:52-57
4. Taylor SS, Goodfellow MR, Browne WJ, Balding B, Murphy S, Tzannes S, Gerou-Ferriani M, Schwartz A, Dobson JM. Feline extranodal lymphoma: response to chemotherapy and survival in 110 cats. J Small Anim Pract 2009;50:584-592
5. Sfiligoi G, Theon AP, Kent MS. Response of nineteen cats with nasal lymphoma to radiation therapy and chemotherapy J Vet Radiol and Ultrasound 2007;48:388-39
6. Haney SM, Beaver L, Turrel J, Clifford CA, Klein MK, Crawford
S, Poulson JM, Azuma C. Survival analysis of 97 cats with nasal lymphoma: a multi-institutional retrospective study (1986-2006) J Vet Intern Med 2009;23:287-294
Your Singapore, the Tropical Garden City
WSV18-0272
OPHTHALMOLOGY
STATE-OF-THE-ART LECTURE FELINE HERPESVIRUS: CONTROL AND THERAPY
D. Maggs1
1Professor Ophthalmology, University of California Davis, USA.
Clinical Presentations
Feline herpesvirus is a ubiquitous virus that varies very little worldwide with respect to their clinical virulence. And yet, we see a huge range of clinical signs in cats infected with this virus. There are probably a large number of reasons for this; however principle among these is likely the host’s response to this virus. FHV-1- naïve kittens infected in the first few weeks of life against a backdrop waning maternal immunity almost inevitably get severe upper respiratory and ocular disease with high morbidity but rare mortality. By contrast, adult cats can undergo viral reactivation with viral shedding and can infect in-contact cats; all without demonstrating clinical signs themselves. These two scenarios represent just the two extremes of infection; within your clinic
you see cats with a huge diversity of clinical signs in between. For this reason, I like to consider clinical signs associated with FHV-1 under one of three broad categories: primary infection, recrudescent infections, and FHV-1-associated syndromes.
Primary Herpetic Disease
Primary ocular FHV-1 infection is characterized by blepharospasm, conjunctival hyperemia, serous ocular discharge that becomes purulent by day 5-7 of infection, mild to moderate conjunctival swelling, and often conjunctival ulcers. Corneal involvement is not reliable; however some cats develop corneal ulcers which are transiently dendritic at the very earliest phase only. These dendrites quickly coalesce to become geographic ulcers. The ocular signs are seen in association
with typical signs of upper respiratory infection. The uncomplicated clinical course is typically 10-14 days; however it is critical to realize that almost all cats become latently infected within ganglia for life. Reactivation from latency is likely in at least 50% of cats, sometimes with viral shedding.
Recrudescent FHV-1 Syndromes
Despite the frequency with which latently infected
cats undergo viral reactivation at the ganglia and viral shedding at peripheral epithelial sites, recrudescent disease occurs in a minority of these. Further, disease severity and tissue involvement can range very widely between individuals and even between episodes in the same cat. Recrudescent conjunctivitis is usually milder than in acute infections, but can become chronic and “smoldering”. Although recrudescent conjunctivitis is
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