Effects of dietary ochratoxin A (OA) and T-2 toxin, fed singly and in combination, were evaluated in growing crossbred pigs. Thirty-six barrows (3 replicates of 3 for each of 4 treatment groups, mean body weight, 18.0 kg) were fed: 0 mg of OA and 0 mg of T-2/kg of feed (control); 2.5 mg of OA/kg of feed; 8.0 mg of T-2/kg of feed; or 2.5 mg of OA plus 8.0 mg of T-2/kg of feed for 30 days. Production performance, serum biochemical, hematologic, immunologic, and pathologic evaluations were made. Body weight and body weight gain were decreased by all toxin treatments, but the combination toxin treatment reduced weight gain more than did either of the toxins administered singly and could be considered additive. Liver weight was decreased by combination treatment, whereas kidney weight was increased by OA treatment. Ochratoxin decreased serum cholesterol, inorganic phosphorus, and alkaline phosphatase values; reduced mean cell volume, hemoglobin concentration, and macrophage phagocytosis; and increased creatinine and total protein values. Consumption of T-2 toxin reduced hemoglobin and serum alkaline phosphatase values. The combination treatment decreased serum cholesterol, gamma-glutamyltransferase, alkaline phosphatase, mean cell volume, hematocrit, and hemoglobin values, as well as lymphoblastogenesis and phagocytosis, and increased serum nine concentration. We concluded that OA and T-2, singly or in combination, can affect clinical performance, serum biochemical, hematologic, and immunologic values, and organ weights of growing barrows. Although some analytes were affected more by the combination than by either toxin alone, the interactions could best be described as additive, not synergistic.

Ceftiofur sodium, a broad-spectrum cephalosporin antibiotic, was evaluated for safe use in horses. Male or female horses were allotted to groups and were given either saline solution (control), or 2.2, 6.6, or 11 mg of an aqueous solution of ceftiofur sodium/kg of body weight/d, IM, for 30 or 31 days. These dosages are expressed in terms of the ceftiofur free acid, and represent 1 to 5 times the proposed therapeutic dosage (2.2 mg/kg/d) administered for 3 times the maximal recommended duration of 10 days. Some of the horses were euthanatized and necropsied on day 31 or 32. The other horses were evaluated for an additional 30 days, and some were euthanatized and necropsied on day 60. The following types of data were collected: clinical observation; physical examination; pelleted food consumption; body weight; hematologic, serum biochemical, and urinalysis findings; organ weight; gross necropsy observations; and histopathologic findings. Ceftiofur sodium was generally well tolerated at the exaggerated doses and treatment durations used in these safety studies. Slight to mild decrease in pelleted food consumption was detected in horses given 6.6 or 11 mg of ceftiofur sodium/kg/d. Decreased food consumption began on day 2 and lasted for approximately 9 to 12 days. Generally, mild skeletal muscle irritation was detected by gross and microscopic examination of the injection sites of horses given ceftiofur sodium. Prevalence and severity of the muscle irritation tended to increase with increasing concentration of the dosing solution. Increases in serum aspartate transaminase and creatine kinase activities were detected in some of the ceftiofur-treated horses, and were attributed to mild skeletal muscle irritation at the injection sites. Slight increases in numbers of circulating neutrophils and plasma concentration of fibrinogen were detected in the blood of some ceftiofur-treated horses, and were attributed to mild inflammation at the injection sites or possibly in the large intestine because of a change in bacterial flora.

Sixteen healthy ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocytes. Of the 16 ponies, 15 developed clinical signs of equine ehrlichial colitis. Twenty-four hours after onset of fever (rectal temperature > 38.8 degrees C), 7 ponies were treated with 25 mg of erythromycin stearate/kg of body weight and 10 mg of rifampin/kg, given orally every 12 hours for 5 days. The remaining 8 ill ponies served as nontreated controls. All ponies were observed for progression of clinical signs typical of equine ehrlichial colitis. Within 12 hours of initiation of treatment, 4 of the 7 treated ponies had rectal temperature < 38.4 C and, within 24 hours, 6 of the 7 ponies had rectal temperature < 38.3C. In contrast, all control ponies had rectal temperature > 39.2 C at 24 hours (P < 0.05). Of the 7 treated ponies, 4 no longer had signs of mental depression after the second day of treatment, and only 1 of the 7 ponies had mild signs of depression after the third day of treatment. In contrast, control ponies had high mental depression score during the observation period (P < 0.05). Feed intake improved in ponies of the treatment group, with feed intake of 4 of the 7 ponies returning to normal; the other 3 ponies were only mildly anorectic by the second day of treatment. Control ponies progressively decreased their feed intake during the observation period (P < 0.05). One control pony and 2 treated ponies developed diarrhea before the treatment/observation period began. Only 1 treated pony developed diarrhea after treatment began. Of the 8 control ponies, 7 developed diarrhea. Profound decrease in borborygmal sounds with silent periods lasting longer than 3 minutes was observed in 7 of the 8 control ponies. Only 1 of the 7 treated ponies had such profound decrease in borborygmi (P < 0.05). The decrease in borborygmal sounds progressed in the control ponies during the observation period. None of the treated ponies continued to have decreased borborygmi after treatment day 2 (P < 0.05). Of the 8 control ponies, 2 were euthanatized; all treated ponies survived. In survivors, signs lasted 8 to 17 (mean, 10) days in control ponies but only 1 to 5 (mean, 2.9) days in treated ponies.

Serum lipoprotein concentrations, routine serum biochemical values, and morphologic changes of the liver were evaluated in cats undergoing weight loss. Food was withheld from 6 obese and 6 control cats for 3 days (days 0 to 2), followed by feeding 50% of previous food intake for 26 days (days 3 to 28). Percutaneous liver biopsy specimens were obtained from all cats on days 0, 7, 14, and 28. Blood samples for serum biochemical analysis and lipoprotein profiles were obtained on days 0, 3, 7, 14, and 28. All cats lost weight throughout the study, and none developed signs of chemical illness, including those of idiopathic hepatic lipidosis syndrome. Serum total cholesterol concentrations decreased initially in all cats, but rapidly returned to normal after day 3 in obese cats, suggesting altered cholesterol metabolism during dietary restriction. Low-density lipoprotein concentrations decreased throughout the study in control cats, but were unchanged in obese cats. Examination of liver biopsy specimens from each cat revealed minimal lipid accumulation in all specimens, although some specimens contained hydropic degeneration.

The bioavailability and pharmacokinetics of ibuprofen, a nonsteroidal antiinflammatory drug, was studied in healthy Shetland ponies. Ibuprofen was administered IV, as a suspension, and as a solid solution oral paste to ponies from which food was withheld. The suspension paste was also administered to ponies that received hay and water ad libitum. Both formulations had an absolute bioavailability of about 80%. Bioavailability was not influenced by feeding.

The effect of intestinal microflora on digestible energy (DE) value and fiber digestion was studied in single-comb White Leghorn chickens fed a low-fiber diet (experiment 1) or a high-fiber diet with low or adequate metabolizable energy (ME) value (experiment 2). Fecal energy excretion was calculated from the difference between total energy excretion in urinary and fecal droppings and urinary energy excretion, which was estimated from the energy values for individual urinary nitrogenous compounds extracted with Li2CO3. When the birds were fed the low-fiber diet, no differences in growth, DE, or ME were observed between germ-free and conventional environments. Of birds fed the high-fiber diet, growth of those in the conventional environment was similar to that of the birds in the germ-free environment at the adequate ME value, whereas birds in the conventional environment grew faster than the birds in the germ-free environment at the low ME value. Changes in observed dietary ME values of the high-fiber diets, being higher in birds in the conventional environment than in birds in the germ-free environment (experiment 2), were almost entirely accounted for by those in dietary DE values, most of which was contributed by crude fiber digestion. It was concluded, therefore, that by means of fiber digestion, the intestinal microflora may benefit the host bird by supplying extra energy, which would result in growth promotion, particularly when the bird is deficient in energy.

Myoelectric activity of the ileum, cecum, and right ventral colon (RVC) was studied in 4 mature ponies. Eight Ag-AgCl bipolar recording electrodes were sutured to the seromuscular layer of the ileum (2 electrodes), cecum (4 electrodes), and RVC (2 electrodes). Myoelectric activity was studied beginning 10 days after surgery. Eight, 60-minute recording sessions were performed in each pony during the interdigestive period, which was the period 3 to 7 hours after the morning feeding. On separate days, food was withheld for 24 hours, and 90-minute recordings were obtained during the nonfeeding period. Ponies were then fed a normal ration, and recordings were continued to obtain data for the digestive (feeding) period. All phases of the migrating myoelectric complex were seen at both ileal electrodes during the interdigestive period, including the periods of no spiking activity (phase 1), irregular spiking activity (phase 2), and regular spiking activity (phase 3). Phase 2 occupied 77% of the total recording time, and the mean duration of phases 1, 2, and 3 was 3.4 +/- 0.2, 12.8 +/- 1.2, and 6.7 +/- 0.7 min, respectively. Frequency of ileal slow waves was 11.8 +/- 0.1/min, and spike burst conduction velocity was 4.7 +/- 0.3 cm/s. A complete migrating myoelectric complex was seen in 11 of 32 tracings (34%) and had a mean duration of 24.2 +/- 2.6 min. The ileal migrating action potential complex, most often seen in phase 2, had a frequency of 4.8 +/- 0.5 spike bursts/h and a conduction velocity of 13.6 +/- 0.4 cm/s. The migrating action potential complex was detected directly before retrograde cecal myoelectric activity 73% of the time, indicating possible myoelectric coupling of the ileum and cecum. Motility patterns recognized in the cecum included: pattern I, spike bursts beginning at the apex and conducted to the cranial base; pattern II, spike bursts beginning at the caudal base and conducted to the apex; pattern III, spike bursts beginning at the cranial base and conducted to the apex; and pattern IV, termed the progressive pattern, beginning at the cecal apex, conducted through the cecal base and cecocolic orifice and into the RVC. The progressive pattern was detected at a frequency of 34.2 +/- 1.8 spike bursts/h and was often preceded by (71%), followed by (64%), or preceded and followed by (51%) pattern I or II. This recurring sequence of cecal myoelectric events was termed the cecal myoelectric complex. In the RVC, 2 patterns of myoelectric activity were seen: aborally directed propulsive spike bursts (3.6 +/- 0.6 spike bursts/h) and orally directed retropulsive spike bursts (7.2 +/- 1.2 spike bursts/h), confirming that propulsion and retropulsion exist in the RVC. Nonfeeding caused a significant decrease in the frequency of ileal migrating action potential complex (P = 0.008), cecal pattern III (P = 0.003), and the progressive motility pattern (P = 0.003). Nonfeeding caused a significant decrease (P less than or equal to 0.009) in the appearance of the cecal myoelectric complex. Feeding caused a significant increase (P = 0.003) in the mean frequency of the progressive pattern compared with the nonfeeding period, but this was significantly less than during the interdigestive period (P = 0.003).

The effect of meal size and frequency on plasma volume, plasma aldosterone concentration and urinary Na and K clearances was determined in ponies. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen, ie, 12 equal portions fed at 2-hour intervals, or as single large feedings, ie, half the ration fed every 12 hours at 0800 and 2000 hours. Only the effect of the single morning feeding was studied, using the latter regimen. Serial measurements of plasma volume were made by use of an indicator-dilution technique and indocyanine green (0.15 mg/kg of body weight, IV) that allowed repeated determinations at 2-hour intervals. Ingestion of the single large meal caused a 15% decrease in plasma volume by the end of a 1-hour feeding period. Feeding hypovolemia was confirmed by a coincident increase in plasma protein concentration (12%) and, in separate experiments, by analysis of postfeeding changes in the elimination of Evans blue dye. Plasma aldosterone concentration was significantly (P < 0.05) increased from 2 to 5 hours after feeding. Urinary Na clearance decreased in response to feeding and remained lower than the prefeeding value until 9 hours after feeding. Urinary K clearance increased from prefeeding and reached a peak value between 5 and 7 hours after feeding. Creatinine clearance was unaffected. In contrast, the aforementioned variables were unchanged during the multiple regimen. Results indicate that ingestion of a large concentrate meal by ponies causes periprandial hypovolemia, activation of the renin-angiotensin-aldosterone system, and a subsequent antinaturesis-kaluresis that lasts for several hours.

Growth indices were examined in 24 identically managed tanks, each containing 120 diploid juvenile rainbow trout (initial mean body weight, 9.3 g), during a 12-week study to examine tank effects associated with tank location in a multi-user research facility. Growth indices included mean body weight, feed intake, feed conversion index, and specific growth rate. The null hypothesis that tank effect had no effect on growth over the 12-week period was rejected (P = 0.038), and mean weight in individual tanks differed by as much as 18.7%. During the study, it was determined that the proximity of tanks to common-use walkways in the facility could affect growth indices. This was indicated by significant differences in the mean fish weights among blocks of tanks served by different header tanks after 4 (P = 0.001) and 8 (P = 0.024) weeks. The block containing tanks of fish with the highest mean weight was nearest to the 2 common-use walkways in the facility. Fish in this block of tanks, compared with those in other blocks, had significantly greater feed intake but no significant differences in conversion efficiency. Compensatory growth, a well known growth attribute in fishes, diminished the difference in mean weight between these blocks of tanks by the end of the study. Comparison of paired tanks within header tank blocks indicated that fish in those located nearest to walkways had higher feeding rates over the 12-week period (P = 0.048), but less efficient teed conversion (P = 0.040) than did fish in matched tanks located farthest from walkways. However, there were no differences in mean weight of fish. Results of this trial document the risks involved in identifying fish in a tank as the experimental unit when treatments are administered to the tank of fish, the latter being the true experimental unit.

Desoxycorticosterone pivalate was administered IM to juvenile Beagles at 0, 2.2, 6.6, or 11 mg/kg of body weight daily over a consecutive 3-day period every 28 days (equivalent to a cumulative monthly dosage of 0, 6.6, 19.8, or 33 mg/kg) for 6 months. Polyuria, polydipsia, and decreases in serum potassium and BUN concentrations were detected while the dogs were being treated. Transient increases in serum sodium concentrations also were detected. The treated males had significant decreases in body weight gain, resulting in an 18% decrease in body weight in the 11-mg/kg dosage group, compared with the controls. The weights of the adrenal glands, epididymides, and testes also were lower in the treated males. Organ weights for the 2.2, 6.6, and 11-mg/kg dosage groups were: 86, 79, and 69%, respectively, of the controls (adrenal glands); 80, 70, and 68%, respectively, of the controls (epididymides); and, 79, 75, and 67%, respectively, of the controls (testes). When normalized to body weight, these decreases in organ weight were still dosage-dependent, but the differences were less remarkable. In contrast, the relative weight (to body weight) of the kidneys (males and females) and of the thyroid and parathyroid glands (males) were higher dosage-dependently. All of the treatment-related effects, other than organ and body weight changes, appeared to be reversible following the cessation of treatment. On the basis of these results, it was concluded that treatment with desoxycorticosterone pivalate could be tolerated, even when given at dosages 15-fold the therapeutic dosage of 2.2 mg/kg every 25 days.