Detection of infectious spleen and kidney necrosis virus (ISKNV) and turbot reddish body iridovirus (TRBIV) from archival ornamental fish samples.

Although infections caused by megalocytiviruses have been reported from a wide range of finfish species for several decades, molecular characterisation of the viruses involved has been undertaken only on more recent cases. Sequence analysis of the major capsid protein and adenosine triphosphatase genes is reported here from formalin-fixed, paraffin-embedded material from 2 archival ornamental fish cases from 1986 and 1988 in conjunction with data for a range of genes from fresh frozen tissues from 5 cases obtained from 1991 through to 2010. Turbot reddish body iridovirus (TRBIV) genotype megalocytiviruses, previously not documented in ornamental fish, were detected in samples from 1986, 1988 and 1991. In contrast, megalocytiviruses from 1996 onwards, including those characterised from 2002, 2006 and 2010 in this study, were almost indistinguishable from infectious spleen and kidney necrosis virus (ISKNV). Three of the species infected with TRBIV-like megalocytiviruses from 1986 to 1991, viz. dwarf gourami Trichogaster lalius (formerly Colisa lalia), freshwater angelfish Pterophyllum scalare and oscar Astronotus ocellatus, were infected with ISKNV genotype megalocytiviruses from 2002 to 2010. The detection of a TRBIV genotype isolate in ornamental fish from 1986 represents the index case, confirmed by molecular sequence data, for the genus Megalocytivirus.

Chytridiomycosis in dwarf African frogs Hymenochirus curtipes.

Chytridiomycosis, resulting from an infection with the fungal agent Batrachochytrium dendrobatidis (Bd), has resulted in widespread population declines in both wild and captive amphibians. The dwarf African frog (DAF) Hymenochirus curtipes is native to central Africa and is commonly sold throughout North America as an aquarium pet species. Here we document fatal chytridiomycosis resulting from cutaneous Bd infections in DAF purchased directly from a pet store and from a historical lethal epizootic occurring at an aquaculture facility in central California, USA, more than 25 yr ago. Histological lesions and PCR-amplified sequence data were consistent with the etiology of Bd. The potential epidemiological relevance of this infection in DAF is discussed.

Evaluation of an extended-release formulation of ceftiofur crystalline-free acid in koi (Cyprinus carpio).

The use of an extended release ceftiofur crystalline-free acid formulation (CCFA, Excede For Swine(®) , Pfizer Animal Health) in koi was evaluated after administration of single intramuscular (i.m.) or intracoelomic (i.c.) doses. Twenty koi were divided randomly into a control group and four treatment groups (20 mg/kg i.m., 60 mg/kg i.m., 30 mg/kg i.c., and 60 mg/kg i.c.). Serum ceftiofur-free acid equivalents (CFAE) concentrations were quantified. The pharmacokinetic data were analyzed using a nonlinear mixed-effects approach. Following a CCFA injection of 60 mg/kg i.m., time durations that serum CFAE concentrations were above the target concentration of 4 µg/mL ranged from 0.4 to 2.5 weeks in 3 of 4 fish, while serum CFAE concentrations remained below 4 µg/mL for lower doses evaluated. Substantial inter-individual variations and intra-individual fluctuations of CFAE concentrations were observed for all treatment groups. Histological findings following euthanasia included aseptic granulomatous reactions, but no systemic adverse effects were detected. Given the unpredictable time vs. CFAE concentration profiles for treated koi, the authors would not recommend this product for therapeutic use in koi at this time. Further research would be necessary to correlate serum and tissue concentrations and to better establish MIC data for Aeromonas spp. isolated from naturally infected koi.

Case report: concurrent herpesviral and presumptive iridoviral infection associated with disease in cultured shortnose sturgeon, Acipenser brevirostrum (L.), from the Atlantic coast of Canada.

Approximately 8 weeks after a chlorine insult associated with the city water supply, shortnose sturgeon, Acipenser brevirostrum (L.), from one group presented with small (3-4 mm) irregular foci of cutaneous pallor that involved the dorsocranial integument with progressive ulceration of the nascent lesions. Various bacterial organisms were isolated from the cutaneous lesions, but not from the internal viscera. Histologically, the nuclei of the intralesional and perilesional epidermal cells often exhibited margination of the chromatin that resulted in a homogenous, pale, amphophilic, tinctorial quality of the nucleoplasm consistent with a herpesvirus infection. In addition, rare lamellar epithelial cells were prominently enlarged due to an abundant, dense, basophilic cytoplasm characteristic of an iridovirus infection. Inoculation of cutaneous lesion and kidney, spleen, liver sample pools from affected shortnose sturgeon onto white sturgeon spleen (WSS-2) cell line induced cytopathic effect characterized by syncytia formation. Ultrastructural analysis of infected WSS-2 cells revealed viral particles with a characteristic herpesvirus morphology. Intranuclear hexagonal capsids had a diameter of 95-108 nm, and enveloped particles present in the cytoplasm of infected cells had a diameter of 176-196 nm. This is the first report of a herpesvirus and a possible iridovirus-like infection in shortnose sturgeon.

Molecular characterization of "Candidatus Parilichlamydia carangidicola," a novel Chlamydia-like epitheliocystis agent in yellowtail kingfish, Seriola lalandi (Valenciennes), and the proposal of a new family, "Candidatus Parilichlamydiaceae" fam. nov. (order Chlamydiales).

Three cohorts of farmed yellowtail kingfish (Seriola lalandi) from South Australia were examined for Chlamydia-like organisms associated with epitheliocystis. To characterize the bacteria, 38 gill samples were processed for histopathology, electron microscopy, and 16S rRNA amplification, sequencing, and phylogenetic analysis. Microscopically, the presence of membrane-enclosed cysts was observed within the gill lamellae. Also observed was hyperplasia of the epithelial cells with cytoplasmic vacuolization and fusion of the gill lamellae. Transmission electron microscopy revealed morphological features of the reticulate and intermediate bodies typical of members of the order Chlamydiales. A novel 1,393-bp 16S chlamydial rRNA sequence was amplified from gill DNA extracted from fish in all cohorts over a 3-year period that corresponded to the 16S rRNA sequence amplified directly from laser-dissected cysts. This sequence was only 87% similar to the reported "Candidatus Piscichlamydia salmonis" (AY462244) from Atlantic salmon and Arctic charr. Phylogenetic analysis of this sequence against 35 Chlamydia and Chlamydia-like bacteria revealed that this novel bacterium belongs to an undescribed family lineage in the order Chlamydiales. Based on these observations, we propose this bacterium of yellowtail kingfish be known as "Candidatus Parilichlamydia carangidicola" and that the new family be known as "Candidatus Parilichlamydiaceae."

Chromatophoromas and chromatophore hyperplasia in Pacific rockfish (Sebastes spp.).

Pacific rockfish from Cordell Bank, off central California (United States), were collected and histologically examined from 1985 to 1990. Hyperplastic and neoplastic cutaneous lesions, involving dermal chromatophores, were observed in five species; yellowtail rockfish (Sebastes flavidus), bocaccio (S. paucispinis), olive rockfish (S. serranoides), widow rockfish (S. entomelas), and chilipepper rockfish (S. goodei). Yearly prevalences were highest in S. paucispinis (29-38%). Prevalence was initially low in S. flavidus, but increased more than 3-fold from 1985 (7.5%) to 1990 (25%). The majority of lesions were black, but white, yellow, orange, red, and mixed-color variants were also seen. Lesions were found in skin, fins, lips, gingiva, tongue, urogenital papilla, conjunctiva, and cornea of the eye. Flat lesions were consistent with melanophore (black), xanthophore (yellow or orange), and erythrophore (red) hyperplasia. Neoplastic lesions included melanophoromas, amelanotic melanophoromas, xanthophoromas, erythrophoromas, and mixed chromatophoromas. Although etiology has not been determined, interest is currently focused on potential exposure to chemical and radioactive carcinogens from the Farallon Island Radioactive Waste Dump, 30 km to the south.

Exploring barriers to utilization of poison centers: a qualitative study of mothers attending an urban Women, Infants, and Children (WIC) Clinic.

OBJECTIVE: Prior research regarding poison center utilization identified risk factors for underutilization including race/ethnicity and acculturation. The purpose of this study was to understand factors contributing to underutilization of poison centers by low-income and minority mothers. METHODS: Focus groups were conducted with women attending an urban Women, Infants and Children clinic. Transcripts were analyzed for themes and key points. RESULTS: Twenty-two English-speaking mothers and 21 Spanish-speaking mothers participated in 7 groups. Participants viewed poisoning as a serious problem to which all children are susceptible. English-speaking mothers had heard of the poison center but were unaware of services provided. They preferred to use the 911 system, which was viewed as immediate medical assistance and was an easy number to remember. Women questioned the credentials of the poison center staff. Spanish-speaking mothers had limited knowledge of poison centers and were concerned about language barriers. CONCLUSIONS: To increase utilization of poison centers, educational interventions must address these specific needs and misconceptions and should be produced in Spanish and English versions.

Diagnosis and radioablation treatment of toxic multinodular goiter in a hemodialysis patient.

Toxic multinodular goiter is rare in hemodialysis patients. In addition, establishing the diagnosis of hyperthyroidism in the elderly patient with renal failure is difficult because abnormal thyroid function tests can erroneously be attributed to euthyroid sick syndrome. Treatment of hyperthyroidism in dialysis patients by radioiodine ablation involves careful calculation of 131I dose, determination of interval between 131I administration and its removal by hemodialysis, and minimization of radiation hazards during dialytic removal of 131I. We described the clinical presentation of an elderly dialysis patient with toxic multinodular goiter and discussed our diagnostic and therapeutic approaches. The patient's recovery after 131I ablation was complete and uneventful.

The evolution of senescence in natural populations of guppies (Poecilia reticulata): a comparative approach.

Model organisms like Drosophila melanogaster or Caenorhabditis elegans have revealed genes that influence senescence and the evolvability of senescence. We are interested instead in evaluating why and how senescence evolves in natural populations. To do so, we are taking the ecological geneticist's perspective of comparing natural populations that differ in factors that are predicted to influence the evolution of senescence and are evaluating whether senescence has evolved in the predicted fashion. We are also manipulating the environment to evaluate more directly the evolution of senescence. Guppies (Poecilia reticulata) are found in streams throughout the Northern Range mountains of Trinidad. Natural populations experience large differences in mortality rate as a consequence of the predators with which they co-occur. We have already shown, both with comparative studies and manipulations of the distribution of guppies and their predators, that the early life history evolves very rapidly in response to these differences in mortality. For example, high adult mortality rates select for individuals that develop more rapidly, produce their first litter of young at an earlier age, and devote more of their available resources to reproduction for the remainder of their lives. These changes were predicted by independently derived theory. Aspects of this same theory also predict how the late life history and senescence should evolve. Specifically, theory predicts that the populations that experience low mortality rates should also experience delayed senescence and longer life spans relative to those that experience high mortality rates. We are currently evaluating these predictions with representatives from two high-predation and two low-predation environments. Our presentation will focus on our pilot study, which evaluated life span, lifetime reproduction, and the patterns of aging in our laboratory populations. We will also report on the progress in our ongoing comparative studies of senescence in natural populations.

Evaluation of a reservoir device for metered-dose bronchodilator delivery to intubated adults. An in vitro study.

UNLABELLED: We investigated the use of a reservoir device for delivery of a MDI bronchodilator aerosol using a lung model of an intubated, mechanically ventilated adult. METHODS: Albuterol (Proventil) was delivered with a MDI using three methods. In method 1, the MDI was attached directly onto the ETT using a commercially available actuator/adapter. In method 2, the Monaghan AeroVent reservoir was placed on the inspiratory limb of the ventilator circuit just before the patient Y connector. In method 3, the AeroVent was placed between the patient Y connector and the ETT. Standardized ventilator settings with a Servo 900C were used for all three methods (VE = 9.6 L; respiratory rate = 12 breaths per minute; TI = 20 percent of 1 s). Aerosol drug delivery was measured at the distal tip of the ETT using a spectrophotometric technique. Percentage of amount delivered was calculated from measured delivery of the MDI. RESULTS: The MDI directly on the ETT delivered 7.3 percent of the total dose to the end of the ETT. The AeroVent on the inspiratory limb increased this to 32.1 percent and the AeroVent between the Y connector and the ETT delivered 29 percent. Both reservoir delivery methods delivered significantly more drug than direct placement of the MDI on the ETT (p less than 0.01) but did not differ from each other (p greater than 0.05). CONCLUSIONS: Use of the AeroVent reservoir chamber significantly increased bronchodilator delivery by aerosol with an MDI in an adult lung model of an intubated patient on ventilatory support.

Applying practical preventive skills in a preclinical preceptorship.

Learning primary care medicine includes learning to apply practical, preventive medicine skills during everyday encounters with patients. The authors relate their experiences with implementing a voluntary, preventive diabetic foot-care program within the Texas Statewide Family Practice Preceptorship Program (TSFPPP). They explain the background of the TSFPPP and their rationale for introducing prevention and selecting diabetic foot care as a first preventive training module. The program's structure, educational materials, and evaluations are described. Of the 158 students and 88 preceptors who were exposed to the program, the authors received evaluations from 86 preceptors and 110 students. Students documented that they had screened and provided foot-care education to 321 diabetic patients. On average, students saved their preceptors 5-10 minutes each time they examined a diabetic patient's feet or provided foot-care education. The students said that the wide variety of preceptors' practices, the time constraints placed upon the preceptors, and the preceptors' own guidelines for the voluntary preceptorship all posed challenges to completing the preventive activities. The preceptors reported that preclinical students could play an important preventive role in their practices; however, to get optimum results from a preventive module, it may be important for students and preceptors to determine which topics are introduced. Using the preceptor's suggestions, the authors are developing a smoking-cessation module.

Epitheliocystis infection in cultured white sturgeon (Acipenser transmontanus): antigenic and ultrastructural similarities of the causative agent to the chlamydiae.

A mild to moderate branchial epitheliocystis infection was diagnosed in subyearling (11 months old, 250-300 g) white sturgeon (Acipenser transmontanus) from a private culture facility with a 4-8% mortality in the population. Infected branchial epithelial cells contained the coccoid to coccobacillary epitheliocystis organisms, which appeared as cytoplasmic inclusions composed of a fine, homogeneous, dense, basophilic, granular material. The infected cells were variably enlarged with spherical to oval profiles and were randomly distributed throughout the branchial epithelium. The cytoplasmic inclusions stained positive with Macchiavello stain but negative with Brown and Brenn, periodic acid-Schiff, and Gimenez stains. Expression of chlamydial antigen was demonstrated within the cytoplasmic inclusions using a standard peroxidase-antiperoxidase immunohistochemical technique. Three stages of coordinated intracellular development were recognized by electron microscopy. The reticulate bodies were oval to spherical and 0.4-0.8 x 0.5-1.4 microns but often exhibited a pleomorphic and convoluted appearance because of variable membrane invaginations and evaginations suggestive of uneven fission and budding. Separate host cells contained intermediate bodies that were spherical to oval and 0.2-0.4 x 0.3-0.6 microns although often observed in the process of apparent uneven division. The presence of a cap or plaque composed of hexagonally arrayed fibrillar surface projections was initially recognized in this stage. A homogeneous population of 0.3-0.4 microns oval elementary bodies were observed separately in individual host cells. This developmental stage had a single, dense, compact, eccentrically located cytoplasmic condensation that occurred opposite to the location of the cap of hexagonally arrayed fibrillar surface projections. Morphologic characteristics of the epitheliocystis organism in these white sturgeon were similar to those previously described in other teleosts and expands the species catalogue of epitheliocystis infection. Furthermore, the ultrastructural similarities to the chalmydiae and the immunohistochemical detection of chlamydial antigen provides further evidence that the epitheliocystis agent is related to members of the Chlamydiales. Although the infection was considered mild to moderate and could not be definitively attributed to the mortality in this population, the potential adverse impact of epitheliocystis infection on sturgeon culture should be considered especially in intensive fish culture operations.

Replication and pathogenesis of white sturgeon iridovirus (WSIV) in experimentally infected white sturgeon Acipenser transmontanus juveniles and sturgeon cell lines.

Characteristics of the in vitro propagation of the white sturgeon iridovirus (WSIV) were examined in 6 sturgeon cell lines. One new cell line originating from gonadal tissues (WSGO) produced up to 12-fold more WSIV [approximately 22 TCID50 (50% tissue culture infective dose) cell-1], than that of a previously established reference spleen cell line (WSS-2). Infected WSGO cell cultures were examined using phase microscopy, viral infectivity assay and transmission electron microscopy (TEM). At 15 degrees C, both mature virions and infectious virus were first detected after 7 d post-infection. Capsids acquired envelopes in the cytoplasm and virions remained primarily cell-associated during the 35 d replication cycle. Cellular changes including hyper-refractility and cytoplasmic swelling with dense cytoplasmic inclusions correlated to extensive proliferation of cytoplasmic vesicles and viral assembly sites. These cytological characteristics corresponded to changes in target cells of WSIV-infected juvenile white sturgeon following bath challenge. Microscopic changes in stained tissue sections of the host epithelium were detected 4 d post-challenge, approximately 8 d prior to the onset of clinical signs. Hypertrophied Malpighian cells surrounded by a prominent pericellular cisternum characterized epithelial lesions in the skin. Similar changes to epithelial cells of the barbels, olfactory organs and esophagus were also observed. Destruction of the sensory epithelium is suggested as a cause for cessation of feeding which occurs early in the infection of white sturgeon juveniles with WSIV.

Development of bovine and porcine embryonic teratomas in athymic mice.

Inner cell masses (ICM) and embryonic discs from bovine and porcine blastocysts of various ages were transplanted under the kidney capsule of athymic (nude) mice to evaluate growth of teratocarcinomas containing both differentiated tissues and undifferentiated stem cells. Inner cell masses were isolated immunosurgically from Day 8, Day 9 and Day 10 porcine blastocysts and from Day 8, Day 10 and Day 12 bovine blastocysts. Embryonic discs were mechanically dissected from Day 11 and Day 12 porcine embryos and from Day 14 bovine embryos. Day 6 egg cylinders were dissected from BALB/C embryos and from hybrid embryos of a cross between BALB/C and an outbred strain of mouse. Two to four ICM, embryonic discs or egg cylinders were transplanted under the kidney capsule of each athymic host. After 8 weeks, graft hosts were killed and their tumors removed, fixed and prepared for histological and immunohistochemical examination. Embryonic teratomas developed at high frequency from murine egg cylinders and from Day 11 and Day 12 porcine and Day 14 bovine embryos. Tumors were observed only infrequently from younger bovine and porcine blastocysts. Murine embryonic tumors were composed of numerous differentiated cell types of ectodermal, mesodermal and endodermal origins, but representation of the three embryonic germ layers was somewhat more restricted in bovine and porcine embryonic tumors. No undifferentiated stem cells were detected in tumors of any of the three species. These results demonstrate that teratomas will develop from bovine and porcine embryos when grafted to an immunocompromised host, but the presence of undifferentiated teratocarcinoma stem cells from these species has yet to be achieved.

Hysterectomy: beliefs and attitudes expressed by African-American women.

OBJECTIVE: Racial/ethnic differences in the rates of hysterectomy have been noted historically. The aim of this study was to explore the beliefs and attitudes of African-American women regarding hysterectomy recommended for non-life threatening conditions. METHODS: Women, aged 30-65 years, were recruited from public health clinics and community agencies for participation in focus groups guided by a semi-structured questionnaire. Transcripts were analyzed both manually and using NUD*IST software. RESULTS: Thirty-eight women participated in six focus groups. Hysterectomy had been recommended for 15% of the women. Four categories and 11 themes emerged from the sessions. Categories included: definitions of hysterectomy and medical indications; resources consulted in the decision-making process; outcomes of hysterectomy; and interactions with the health care community. CONCLUSION: It is important to assess a patient's perceptions and preferences regarding treatment options. The women in this study advocated the delay or avoidance of surgery, or the use of alternative methods of treatment in lieu of hysterectomy for non-cancerous conditions. Physicians who recommend hysterectomy should consider the attitudes, beliefs, and knowledge of patients.

Factors associated with residents' attitudes toward dying patients.

BACKGROUND AND OBJECTIVES: Management of the dying patient often elicits anxiety in physicians. This study identified the association of physicians' personal fear of death, tolerance of uncertainty, and attachment style with physician attitudes toward dying patients. METHODS: Four psychological scales were distributed to family practice residents located in Texas, Missouri, and Maine. The scales were "Death Anxiety," "Death Attitudes," "Physicians' Reactions to Uncertainty," and "Experiences in Close Relationships." The scores from the measures and demographic data were used to determine which factors were associated with physician attitudes toward caring for terminally ill patients. RESULTS: Completed surveys were received from 157 residents. Younger residents (< 30 years) reported more stress from uncertainty and were more uncomfortable with the care of dying patients. Residents who reported higher death anxiety were also more uncomfortable with caring for dying patients. In a multivariate analysis, uncertainty, death anxiety, and age predicted 26% of the total outcome variance of the death attitudes score. CONCLUSIONS: Physician tolerance of uncertainty plays a significant role in physician attitudes toward the dying patient. Our findings suggest that decreasing physicians' stress from uncertainty by educating them in the management of the dying patient may improve their attitude toward death and may better prepare them to provide end-of-life care.

Vesiculobullous cutaneous lymphatic reflux.

Although lymphedema is a fairly common condition, cutaneous vesicles and bullae due to reflux of lymphatic fluid are rare. We describe a patient with adenocarcinoma of the cervix treated by radiation in whom acute secondary lymphedema with overlying clear vesicles and bullae developed. Histopathologic examination revealed a subepidermal vesicle communicating directly with a dermal lymphatic vessel. Vesicles occur only in lymphedema of acute onset. Vesiculobullous cutaneous lymphatic reflux should be recognized as a rare complication of lymphedema and included in the differential diagnosis of cutaneous blistering disease.

Efficacy of bolus intravenous iron dextran treatment in peritoneal dialysis patients receiving recombinant human erythropoietin.

The efficient use of recombinant human erythropoietin (rHuEPO) requires adequate body stores of iron. In peritoneal dialysis (PD) patients, iron replacement is most commonly administered orally. In this study, we prospectively followed 7 stable PD patients following bolus intravenous infusion of 1 g iron dextran in an outpatient setting. At 12 weeks, significant (p < 0.05) increments in mean hematocrit from 29.13% to 34.85%, transferrin saturation from 10.15% to 29.33%, serum iron from 27.38 to 67.00 micrograms/dL, and serum ferritin from 150.30 to 331.40 ng/mL were observed. Post-treatment, there was less requirement of rHuEPO, and at six months there was a 26% reduction in the mean weekly subcutaneous rHuEPO dose. At 12 weeks, serum albumin increased significantly from 3.50 to 3.76 g/dL (p < 0.05). There was no abnormality in any of the measured liver function tests. No patient developed an adverse or allergic reaction. We concluded that bolus intravenous infusion of iron dextran is an effective and well-tolerated method of repleting iron stores, and will allow a more efficient and economic use of rHuEPO in PD patients.

Effects of protein, lipid, or carbohydrate supplementation on hepatic lipid accumulation during rapid weight loss in obese cats.

Effects of restricted tube-feeding (25% of energy requirements) of protein, lipid, or carbohydrates on body weight loss; hematologic and clinical chemical variables; plasma lipid and amino acid concentrations; nitrogen balance; and hepatic histologic features and lipid concentrations were compared with values in voluntary-fasting cats (control, CON). Twelve obese cats (6.1 +/- 0.1 kg, > 40% above optimal body weight) were randomly assigned to 4 matched treatment groups (n = 3)--protein (PRO), lipid (LIP), carbohydrate (CHO), and CON--and were offered a low-palatability diet for 4 weeks. Cats of the PRO, LIP, and CHO groups were also tube-fed isocaloric amounts (88 kcal of metabolizable energy) of a casein-soybean protein mixture, corn oil, or a dextrin-dextrose mixture, respectively, during the 4 weeks. All cats fasted, rather than eat the low-palatability purified diet. Cats of the PRO group lost weight at a lower rate (P < 0.05) than did cats of other groups. After 4 weeks of fasting, serum alkaline phosphatase activities were higher than reference values in all cats of the CON and LIP groups and in 2 cats of the CHO group. At that time, 1 cat of the LIP group had lethargy, hepatomegaly, and hyperbilirubinemia. Total hepatic lipid and triglyceride concentrations increased in all groups during the study, but the increase was significantly (P < 0.05) less in cats of the PRO group, compared with those of the CON and LIP groups, and those of the CHO group, compared with those of the LIP group.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum concentrations of gentamicin in cats.

Twenty-one adult cats, allotted into 2 groups, were given gentamicin sulfate at dosages of either 5.0 mg/kg of body weight or 2.5 mg/kg as a single IM injection. During a 24-hour period, serum concentrations of gentamicin were measured serially, using a fluorescence immunoassay. The mean peak serum concentration of gentamicin in cats given 5.0 mg/kg was 23.1 micrograms/ml at postinjection hour (PIH) 0.5; thereafter, the mean serum concentration steadily decreased to 2.0 micrograms/ml at PIH 24. The mean peak serum concentration for cats administered 2.5 mg/kg was 9.1 micrograms/ml at PIH 0.5; thereafter, the mean serum concentration steadily decreased to 1.3 micrograms/ml at PIH 12. Serum therapeutic concentrations, without exceeding toxic concentrations, were attained at the 2.5 mg/kg dosage.