Small Animal Flashcards
What sites contain Igs normally, and should therefore not be collected for immunofluorescence testing?
nasal planum of dogs and cats, footpads of dogs
What is Michel fixative?
fixative used for samples submitted for direct immunofluorescence testing. Samples can be held in this for up to 2 weeks. pH: 7.0-7.2
immunoperoxidase testing can yield false POSITIVE or false NEGATIVE results?
false positive
What are the phases of treatment as it relates to immune-mediated dermatoses?
(1) induction of remission, (2) transition, (3) maintenance, and (4) determining cure
Goal of Induction phase:
avoid bad side effects; can take days to weeks
goal of transition phase:
get to lowest effective dose, takes weeks to months
goal of maintenance phase:
maintain dose for duration of disease with monitoring to avoid adverse effects, takes 6 mos to years
goal determining cures:
stop drugs after complete remission has been maintained and observe for recurrence of disease; may take several attempts
Azathioprine is what kind of drug?
Synthetic modification of 6-mercaptopurine; antagonizes purine metabolism and interferes with DNA/RNA synthesis. metabolized in the liver to 6-mercaptopurine and other active metabolites. 6-Mercaptopurine is then metabolized by three enzyme systems. 1) Xanthine oxidase and 2) thiopurine methyltransferase (TPMT) produce inactive metabolites. Humans and possibly dogs that have absent (homozygous) or low (het- erozygous) TPMT activity are more likely to experience myelo- suppression; cats have lower levels, making them more susceptible to toxicity 3) hypoxanthine phosphoribosyltransferase
What is azathioprine metabolized to and by which enzyme system?
Metabolized to 6-mercaptopurine (and other active metabolites) -Xanthine oxidase and thiopurine methyltransferase (TPMT) produce inactive metabolites - if TMPT is low, can have more myelosuppression
what drugs do you NOT want to use with azathioprine?
allopurinol
what are potential side effects of azathioprine?
bone marrow suppression! hepatotoxicity (but rare, and usually in combo) (CEG: as long as acting normal, and bilirubin not up, ok to see some liver values change) anemia, leukopenia (lymphopenia**), demodicosis, thrombocytopenia, vomiting, hypersensitivity reactions (especially of the liver), pancreatitis (esp if also on steroids), elevated serum alkaline phosphatase concentrations, rashes, and alopecia, diarrhea (hemorrhagic) - most respond to drug reductions,
How long is the lag time for azathioprine?
There is often a lag phase, with clinical improvement occurring in 3 to 6 weeks
What are adverse effects of azathioprine in cats (and why should AZA NOT BE USED IN CATS)?
fatal leukopenia and thrombocytopenia)
what is chlorambucil?
alkylating agent derived from nitrogen mustard. Its cytotoxic effect is due to cross-linking of DNA
what are potential side effects of chlorambucil?
v/d, anorexia, alopecia and delayed hair growth after clipping have been reported, (poodles and Kerry blue terriers are reported to be at greater risk)
what’s a potential side effect of cyclophosphamide?
STERILE HEMORRHAGIC CYSTITIS (30% of dogs on it for >2 mos), bladder fibrosis, teratogenesis, infertility, alopecia and poor hair growth, nausea, GI inflammation, bone marrow suppression
what is colchicine?
alkaloid that suppresses neu- trophil chemotactic and phagocytic functions via disruption of microtubule assembly and elongation, increasing cellular cyclic adenosine monophosphate (cAMP) levels and inhibiting lysosomal degranulation -It also inhibits immunoglobulin secretion, interleukin (IL)-1 production, histamine release, and human leukocyte antigen (HLA)-DR expression. -inhibits cell division during metaphase by interfering with sol-gel formation and the mitotic spindle. **antifibrotic**
What drugs should not generally be used with colchicine?
NSAIDs - concern with concurrent use and bone marrow suppression don’t use with azathioprine or chlorambucil
What is cyclophosphamide?
nitrogen mustard alkylating agent metabolized to agents that inhibit mitosis via interferring with DNA replication and RNA transcription and replication
what cell line is most sensitive to cyclophosphamide?
lymphocytes - especially b cells suppresses antibody production
What is the MOA of mycophenolate mofetil?
=prodrug is antiproliferative agent mycophenolic acid (MPA) and specifically and reversibly inhibits inosine monophosphate dehydrogenase –> thereby inhibits purine (guanine) synthesis and prevents maturation of B and T lymphocytes -inhibits de novo synthesis of purine -suppresses T and B lymphocytes -induces lymphocyte apoptosis -induced dendritic cell maturation -decreases IL-1 expression -enhances expression of IL-1R antagonist
Mycophenolate mofetil has a synergitic effect with which other immune suppressive drug?
CsA
What are some side effects of mycophenolate mofetil?
bone marrow suppression, nausea, vomiting, diarrhea, increased incidence of infections -GI side effects more common when drug is given as sodium enteric-coated tablet
MOA of tetracycline/niacinamide for immune-mediated or inflammatory disease treatment?
unknown
properties of tetracycline?
-suppression of in vitro lymphocyte blastogenic transformation and antibody formation -inhibits matrix metalloproteinases** -inhibits prostaglandin synthesis
properties of Niacinamide?
-block antigen IgE-induced histamine release in vivo and in vitro -prevents mast cell degranulation -photoprotectants from inducing immunologic damage -cytoprotectant that blocks inflammatory cell activation and apoptosis -inhibits phosphodiesterase -decreases protease release -ANTIOXIDANT -ALSO AVAILABLE TOPICALLY
which has a longer half-life: doxycycline or tetracycline?
doxycycline - can use lower dose and longer interval between doses (tetracycline TID)
what does “panepidermal pustular pemphigus” refer to?
cases that have acantholysios, neutrophilic and eosinophilic infiltrate throughout the epidermis (i.e. PVeg and PEryth)
What are primary targets in PF?
Desmocollin 1 and Desmoglein 1
what are primary targets in PV?
Desmoglein 3 (deeper, mucosal involvement)
what are the primary targets in paraneoplastic pemphigus?
plakin famaily antigens: envoplakin and periplakin
what subclasses of immunoglobulin deposits are seen in pemphigus?
IgG2 and IgG4 -intraepidermal Ig deposits are not specific for pemphigus and may be found in 20% of other dermatoses
indirect immunofluorescence is most reliable on which types of tissue for PF and PV?
PF: neonatal mouse skin PV: canine gingival mucosa
What are three possible immunopathogenic pathways proposed for mechanism by which autoantigens exert their effects?
1) antibodies act by steric hindrance 2) antibody binding triggers intracellular signaling events leading to aberrant phosphorylation of Dsg3 and depleted desmosome formation. protein kinases are modulated by protein kinase inhibitors here. 3) intercellular cohesion is dependent on cholinergic mechanisms with Acetylcholine receptor playing a role in controlling phosphorylation of adhesion molecules: –atropine and muscarinic Ach antagonists decrease Dsg phosphorylation –> abnormal desmosome formation
T/F: urokinase plasminogen activator (uPA) plays a pivotal role in acantholysis.
F
what are some drugs that have been involved with drug-induced pemphigus?
PF: cimetidine, itraconazole or Lime sulfur, amitraz/metaflumizone (Promeris) - promeris may have triggered it vs induced PV: polymyxin-B
What breeds are overrepresented in cases of PF?
akitas, chow chows also: cockers, dachshunds, labrador retrievers, english bulldogs
What is the inciting cause of PF?
usually idiopathic, but possible drug-induced or drug-triggered, a subset may develop subsequent to chronic skin disease (allergies), possibly UV light can exacerbate?
which body sites are predisposed to PF lesions?
head, face, ears - often bilaterally symmetric nasal depigmentation later in disease footpads too
which disease shows nasal depigmentation 1st: DLE or PF?
DLE; usually a later event in PF
What is the target antigen for Acquired junctional epidermolysis bulls (AJEB)?
Target antigen: laminin 332 histo: may be acellular Features: ears, oral cavity, pads, nasal or perinasal Collagen IV location: 100% bottom of blisters Salt split IF deposition: both or bottom
What is the target antigen for Bullous Pemphigoid (BP)?
Target antigen: Collagen XVII Histo: eosinophils intact or degranulated; sub epidermal cleft and vesicle formation Features: haired skin usually affected, occasional mucosal lesions likely - SPARES PAW PADS Collagen IV location: both Salt split IF deposition: top IgG and IgM are most commonly detected, with some C3
What is the target antigen for Bullous Systemic Lupus Erythematosus type I (BSLE-I)
Target antigen: Collagen VII Histo: Neutros and histiocytes Collagen IV location: suspected like EBA (mostly above) Salt split deposition: bottom
What is the target antigen for Epidermolysis Bullosa acquisitor (EBA)?
Target antigen: Collagen VII Histo: neutrophils +/- Eos, sub epidermal micro abscesses Features: concave pinnae, oral cavity, pads and friction sites, multifocal-generalized Collagen IV location: 43% above, 29% below, 29% both Salt split deposition: bottom
What is the target antigen for Linear IgA Disease?
Target antigen: Shed collagen XVII Histo: mild to no inflammation Features: one case report only Collagen IV location: below Salt split deposition: top
What is the target antigen for Mixed AISBD?
Target antigen: Laminin 332 and collagen VII Histo: cellular vesicles, dermal neuts and eos Features: affects haired skin and mucosal sites, 2/3 erythematous base to vesicles Collagen IV location: 100% below Salt split deposition: bottom