Objective—To describe pharmacokinetics of multidose
oral administration of tacrolimus in healthy cats
and evaluate the efficacy of tacrolimus in the prevention
of allograft rejection in cats with renal transplants.
Animals—6 healthy research cats.
Procedure—Cats received tacrolimus (0.375 mg/kg,
PO, q 12 h) for 14 days. Blood tacrolimus concentrations
were measured by a high performance liquid
chromatography-mass spectrometry assay. Each cat
received an immunogenically mismatched renal allograft
and native kidney nephrectomy. Tacrolimus
dosage was modified to maintain a target blood concentration
of 5 to 10 ng/mL. Cats were euthanatized
if plasma creatinine concentration exceeded 7 mg/dL,
body weight loss exceeded 20%, or on day 50 after
surgery. Kaplan-Meier survival curves were plotted for
6 cats treated with tacrolimus and for 8 cats with
renal transplants that did not receive immunosuppressive
Results—Mean (± SD) values of elimination half-life,
time to maximum concentration, maximum blood concentration,
and area under the concentration versus
time curve from the last dose of tacrolimus to 12 hours
later were 20.5 ± 9.8 hours, 0.77 ± 0.37 hours, 27.5 ±
31.8 ng/mL, and 161 ± 168 hours × ng/mL, respectively.
Tacrolimus treated cats survived longer (median, 44
days; range, 24 to 52 days) than untreated cats (median,
23 days; range, 8 to 34 days). On histologic evaluation,
3 cats had evidence of acute-active rejection, 1 cat
had necrotizing vasculitis, and 2 cats euthanatized at
study termination had normal appearing allografts.
Conclusions and Clinical Relevance—Tacrolimus
may be an effective immunosuppressive agent for
renal transplantation in cats. (Am J Vet Res 2003;64:926–934)
Objective—To determine whether histopathologic
changes are detectable in grossly normal medial
menisci from dogs with rupture of the cranial cruciate
Sample Population—40 medial menisci from dogs
with rupture of the CCL and 20 medial menisci from
control dogs without stifle joint disease.
Procedure—Data evaluated included age, duration of
clinical signs, and whether rupture of the CCL was
complete or incomplete. Three groups (n = 20/group)
were also compared on the basis of 5 histologic criteria;
group-1 menisci appeared grossly normal and
were obtained from dogs with naturally occurring rupture
of the CCL, group-2 menisci were grossly abnormal
and were also obtained from dogs with naturally
occurring CCL ruptures, and group-3 menisci were
collected at postmortem from dogs without stifle
joint disease that were of similar age and weight as
dogs in groups 1 and 2.
Results—Group-2 menisci were significantly different
from group-1 and -3 menisci in all histologic criteria.
Group-1 menisci were significantly different from control
menisci in only 1 of the 5 histologic criteria (cartilage
differentiation). Dogs that were ≥ 3 years old had
significantly more surface cellularity than did dogs
that were < 3 years old. A significant difference was
not detected between groups 1 and 2 with regard to
completeness of rupture.
Conclusions and Clinical Relevance—Histologic
changes in meniscal cartilage correlate with gross
appearance of the cartilage at time of surgery for rupture
of the CCL. On the basis of minimal histologic
changes, routine removal of grossly normal menisci
does not appear to be warranted. (J Am Vet Med