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Summary

The third article of this 4-part series discusses drug therapy in cats by therapeutic category. Specifically, the use of drugs to control infections, pain, fever, inflammation, cancer, and selected parasites is described. In addition, the use of hormonally related drugs and selected miscellaneous drugs in cats is addressed. Drugs emphasized are those for which use in cats is frequently associated with adverse reactions or drugs for which use is limited to illnesses that tend to be unique in cats.

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in Journal of the American Veterinary Medical Association

Summary

The goal of this series of articles has been to provide a comprehensive review of the literature regarding recommended dosing regimens, therapeutic indications and contraindications, and potential side effects of drugs used in cats. In this fourth and last article, the available information regarding dosage regimens in cats has been consolidated in tabular form to facilitate an effective and rational approach to the pharmacologic prevention and treatment of a variety of feline medical disorders.

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in Journal of the American Veterinary Medical Association

Summary

In the second part of this 4-part series, drug therapy in cats is discussed by use of a systems approach. Specifically, drugs that can be used safely for treatment of disorders affecting the feline gastrointestinal, central nervous, respiratory, cardiovascular, and urogenital systems are described. Many drugs that are used in dogs can be safely used in cats according to the same or similar dosing regimens. Several drugs that have traditionally been considered inappropriate (eg, morphine derivatives, primidone) can probably also be used, if cautiously, in cats. In contrast, use of several drugs that are safely used in other species should be avoided in cats (eg, selected emetics and antiemetics, phosphate salt enemas, and selected urinary antiseptics). Cats are more sensitive than dogs to the adverse side effects of a variety of drugs (eg, aspirin, digoxin, selected antiarrhythmics), and extra precautions must be taken when these drugs are used in cats. Finally, several drugs are used for the treatment of illnesses that tend to be unique to cats (eg, taurine and calcium-channel blockers in selected feline cardiovascular disorders).

Free access
in Journal of the American Veterinary Medical Association

Summary

This is the first of a 4-part series concerning drug therapy in cats. In this article, factors that may increase the incidence of type-A adverse drug reactions in cats are discussed. Factors related to species and age differences, drug interactions, and the effects of disease are emphasized. Those that tend to be unique to cats, such as species-induced differences in drug disposition, are described in detail when sufficient information was available from the literature. General recommendations regarding drug administration are made, which will facilitate the implementation of rational drug therapy in cats, thus reducing the incidence of adverse reactions.

Free access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine pharmacokinetics of buprenorphine in dogs after IV administration.

Animals—6 healthy adult dogs.

Procedures—6 dogs received buprenorphine at 0.015 mg/kg, IV. Blood samples were collected at time 0 prior to drug administration and at 2, 5, 10, 15, 20, 30, 40, 60, 90, 120, 180, 240, 360, 540, 720, 1,080, and 1,440 minutes after drug administration. Serum buprenorphine concentrations were determined by use of double-antibody radioimmunoassay. Data were subjected to noncompartmental analysis with area under the time-concentration curve to infinity (AUC) and area under the first moment curve calculated to infinity by use of a log-linear trapezoidal model. Other kinetic variables included terminal rate constant (kel) and elimination half-life (t1/2), plasma clearance (Cl), volume of distribution at steady state (Vdss), and mean residence time (MRT). Time to maximal concentration (Tmax) and maximal serum concentration (Cmax) were measured.

Results—Median (range) values for Tmax and MRT were 2 minutes (2 to 5 minutes) and 264 minutes (199 to 600 minutes), respectively. Harmonic mean and pseudo SD for t1/2 were 270 ± 130 minutes; mean ± SD values for remaining pharmacokinetic variables were as follows: Cmax, 14 ± 2.6 ng/mL; AUC, 3,082 ± 1,047 ng•min/mL; Vdss, 1.59 ± 0.285 L/kg; Cl, 5.4 ± 1.9 mL/min/kg; and, kel, 0.0026 ± 0.0,012.

Conclusions and Clinical Relevance—Pharmacokinetic variables of buprenorphine reported here differed from those previously reported for dogs. Wide variations in individual t1/2 values suggested that dosing intervals be based on assessment of pain status rather than prescribed dosing intervals.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate a fluorescence resonance energy transfer quantitative PCR (FRET-qPCR) assay for detection of gyrA mutations conferring fluoroquinolone resistance in canine urinary Escherichia coli isolates and canine urine specimens.

SAMPLE 264 canine urinary E coli isolates and 283 clinical canine urine specimens.

PROCEDURES The E coli isolates were used to validate the FRET-qPCR assay. Urine specimens were evaluated by bacterial culture and identification, isolate enrofloxacin susceptibility testing, and FRET-qPCR assay. Sensitivity and specificity of the FRET-qPCR assay for detection of gyrA mutations in urine specimens and in E coli isolated from urine specimens were computed, with results of enrofloxacin susceptibility testing used as the reference standard.

RESULTS The validated FRET-qPCR assay discriminated between enrofloxacin-resistant and enrofloxacin-susceptible E coli isolates with an area under the receiver operating characteristic curve of 0.92. The assay accurately identified 25 of 40 urine specimens as containing enrofloxacin-resistant isolates (sensitivity, 62.5%) and 226 of 243 urine specimens as containing enrofloxacin-susceptible isolates (specificity, 93.0%). When the same assay was performed on E coli isolates recovered from these specimens, sensitivity (77.8%) and specificity (94.8%) increased. Moderate agreement was achieved between results of the FRET-qPCR assay and enrofloxacin susceptibility testing for E coli isolates recovered from urine specimens.

CONCLUSIONS AND CLINICAL RELEVANCE The FRET-qPCR assay was able to rapidly distinguish between enrofloxacin-resistant and enrofloxacin-susceptible E coli in canine clinical urine specimens through detection of gyrA mutations. Therefore, the assay may be useful in clinical settings to screen such specimens for enrofloxacin-resistant E coli to avoid inappropriate use of enrofloxacin and contributing to antimicrobial resistance.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To establish a dosing regimen for potassium bromide and evaluate use of bromide to treat spontaneous seizures in cats.

Design—Prospective and retrospective studies.

Animals—7 healthy adult male cats and records of 17 cats with seizures.

Procedure—Seven healthy cats were administered potassium bromide (15 mg/kg [6.8 mg/lb], PO, q 12 h) until steady-state concentrations were reached. Serum samples for pharmacokinetic analysis were obtained weekly until bromide concentrations were not detectable. Clinical data were obtained from records of 17 treated cats.

Results—In the prospective study, maximum serum bromide concentration was 1.1 ± 0.2 mg/mL at 8 weeks. Mean disappearance half-life was 1.6 ± 0.2 weeks. Steady state was achieved at a mean of 5.3 ± 1.1 weeks. No adverse effects were detected and bromide was well tolerated. In the retrospective study, administration of bromide (n = 4) or bromide and phenobarbital (3) was associated with eradication of seizures in 7 of 15 cats (serum bromide concentration range, 1.0 to 1.6 mg/mL); however, bromide administration was associated with adverse effects in 8 of 16 cats. Coughing developed in 6 of these cats, leading to euthanasia in 1 cat and discontinuation of bromide administration in 2 cats.

Conclusions and Clinical Relevance—Therapeutic concentrations of bromide are attained within 2 weeks in cats that receive 30 mg/kg/d (13.6 mg/lb/d) orally. Although somewhat effective in seizure control, the incidence of adverse effects may not warrant routine use of bromide for control of seizures in cats. (J Am Vet Med Assoc 2002;221:1131–1135)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of cephalexin and enrofloxacin on results of 4 commercially available urine glucose tests in dogs.

Animals—6 healthy adult female dogs.

Procedure—In a crossover design, cephalexin (22 and 44 mg/kg [10 and 20 mg/lb], PO, q 8 h) or enrofloxacin (5 and 10 mg/kg [2.3 and 4.5 mg/lb], PO, q 12 h) was administered to dogs for 1 day. Urine samples were tested for glucose at 0, 6, and 24 hours after drug administration. In vitro, dextrose was added to pooled glucose-negative canine urine samples containing either no antimicrobial or known concentrations of either antimicrobial; urine samples were then tested for glucose.

Results—In vivo, false-positive results were obtained by use of a tablet test in the presence of both antimicrobials and by use of a strip test in the presence of cephalexin. In vitro, false-positive results were obtained with the tablet test at the highest urine concentration of cephalexin (2,400 μg/mL) and with a strip test at the highest concentration of enrofloxacin (600 μg/mL). Enrofloxacin in urine samples containing dextrose caused the urine glucose tests to underestimate urine glucose concentration.

Conclusions and Clinical Relevance—Cephalexin and enrofloxacin at dosages used in clinical practice may result in false-positive or false-negative urine glucose results, and care should be taken when using urine as a basis for identifying or monitoring diabetic animals. (J Am Vet Med Assoc 2004;224:1455–1458)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To characterize the effects of serum separation tubes (SST) on serum drug concentrations.

Sample Population

Clinically normal dogs (clorazepate, n = 7) or dogs with epilepsy (phenobarbital, n = 7) were studied in experiment 1, and samples submitted for therapeutic drug monitoring (n = 87) were studied in ex-periment 2.

Procedure

In experiment 1, blood containing either drug was placed in 2 types of 4-ml SST (SST-A and SST-B) and in nonserum separation tubes (non-SST [control]). Samples were processed, then stored at 20 to 22 C (both drugs) or 10 C (phenobarbital only). Aliquots were collected for 96 hours. The rate constant of disappearance and the percentage decrease of each drug over time were determined for each tube. For experiment 2, paired samples were collected in non-SST and SST and submitted by mail for therapeutic drug monitoring. The SST samples were either decanted from SST prior to shipment (group 1; n = 30) or mailed in SST with serum in contact with the silica gel (group 2; n = 57). Drug concentrations and drug elimination half-life were compared between groups. For both experiments, drugs were detected in samples, using polarized immunofluorescence.

Results

For experiment 1, the rate constant of drug disappearance for both drugs was greater in the 4-ml SST-A (P <0.0001). This SST also caused the greatest percentage decrease (20% for phenobarbital and 35% for benzodiazepines) at 96 hours. Refrigeration reduced the mean decrease in phenobarbital at 96 hours to 11%. For experiment 2, phenobarbital concentration was lower for both SST, compared with non-SST (P < 0.0005). Phenobarbital had decreased a mean 6.4 ± 0.5% in group-1 and a mean 30.5 ± 11.1% in group-2 (P < 0.0005) samples.

Conclusion

The SST should be avoided when collecting serum for monitoring of either phenobarbital or benzodiazepines.

Clinical Relevance

The SST can falsely decrease serum drug concentrations and should be avoided when collecting blood for therapeutic drug monitoring. (Am J Vet Res 1996;57:1299-1303)

Free access
in American Journal of Veterinary Research