Gentamicin sulfate-induced nephrotoxicosis was compared in 2 groups of horses fed different rations. Four horses were fed only alfalfa hay, and 4 other horses were fed only whole oats. Seven days after initiation of the diet, all horses were given gentamicin IV (5 mg/kg of body weight) every 12 hours for 22 days. Urinary gamma-glutamyltransferase to urinary creatinine (UGGT:UCr) ratio was calculated daily, and serum concentration of gentamicin was measured at 1 and 12 hours after drug administration. Results indicated that horses fed oats had greater renal tubular damage than did horses fed alfalfa. Mean UGGT:UCr for horses fed alfalfa was 47.1 +/- 18.8 and was 100.0 +/- 19.0 for horses fed oats (P = 0.007). The UGGT:UCr in horses fed oats was > 100 for a total of 54 days; horses fed alfalfa had UGGT:UCr > 100 for only 7 days. Two horses not given gentamicin were fed only oats and 2 were fed only alfalfa. These horses had mean UGGT:UCr of 17.6 +/- 2.2 and 30.5 +/- 3.0, respectively. Mean peak and trough concentrations of gentamicin were statistically different for horses fed oats and those fed alfalfa (peak 23.16 +/- 1.87 and 14.07 +/- 1.79 microgram/ml, respectively [P = 0.0001], and trough, 1.81 +/- 0.69 and 0.71 +/- 0.70 microgram/ml, respectively [P = 0.02701)]. Mean half-lives of gentamicin (estimated from peak and trough concentrations) for horses fed alfalfa (2.58 +/- 0.26 hours) and horses fed oats (2.88 +/- 0.27 hours) were not significantly different. Horses fed only oats had greater degree of gentamicin-induced nephrotoxicosis than did those fed only alfalfa.

The purpose of this study was to document the effect of calfhood vaccination for Mycobacterium paratuberculosis on a serologic ELISA. Fifteen calves vaccinated with a killed paratuberculosis vaccine and 5 unvaccinated control calves were tested from the first through the fifteenth month of life. Age of vaccination ranged from 5 to 40 days. Blood samples were collected prior to vaccination and periodically thereafter. Serum antibody was analyzed by use of the ELISA. All calves were Elisa-negative prior to vaccination. Thirteen of 15 vaccinated calves became ELISA-positive between 2 and 6 months after vaccination. The unvaccinated cohort remained Elisa-negative. Widespread use of vaccine may interfere with diagnosis of paratuberculosis and with control programs that are based on serologic tests that measure humoral antibody.

Pathophysiologic effects of Ostertagia ostertagi infection and their prevention by strategic anthelmintic treatments were studied in 3 groups each of 6 steer calves. Group-1 calves were noninfected controls. Group-2 calves were inoculated with 100,000 third-stage larvae on the 1st and 28th days of the experiment and grazed on pasture initially free of contamination. Group-3 calves were on a similar regimen as those in group 2, but were also treated with ivermectin 9 days after each larval inoculation. Group-2 calves had increased plasma pepsinogen and gastrin values and decreased weight gains, and total serum protein and albumin concentrations from the 2nd week of infection onward. They were anemic at 10 to 12 weeks and had lower carcass and meat quality at slaughter. Strategic anthelmintic treatments were effective in preventing these effects and calves in groups 1 and 3 had similar performances. On the basis of our findings, high pepsinogen values were related to worm burdens, whereas high gastrin concentrations were related to gastric lesions.

A technique for detection of bovine viral diarrhea virus (BVDV) from circulating blood leukocytes, using the polymerase chain reaction, is described. The published nucleotide sequences of 2 strains of BVDV and that of hog cholera virus were aligned and the information was used to design oligonucleotides coding for 2 regions of amino acid homology. The oligonucleotides were a mixed population including all possible codons for the conserved amino acids. These degenerate oligonucleotides were used in the polymerase chain reaction to detect viral RNA in cells infected in vitro, or in circulating blood leukocytes from infected animals. Virus was detected in over 60 samples from diverse isolates. The detection of BVDV by the polymerase chain reaction is a rapid, sensitive, and specific technique, which represents an improvement over existing technology.

Ten foals of various breeds were deprived of colostrum from birth to 36 hours of age, then were allotted to 2 groups. Foals of group 1 (n = 6) were given 20 g (200 ml) of purified equine IgG IV in a 10% solution, and foals of group 2 (n = 4) were given 30 g (300 ml) of the same preparation. Total administration time for each 10 g of IgG in 100 ml was approximately 10 minutes. Serum IgG concentration in foals was assessed prior to, between 24 and 48 hours, and at 7 and 14 days after IgG administration. Between 24 and 48 hours after IgG administration, mean serum IgG concentration in group-1 foals was 425 mg/dl (range, 350 to 480 mg/dl). Mean body weight for this group of foals was 50.3 kg (range, 43.3 to 54.7 kg). For group-2 foals, mean serum IgG concentration was 768 mg/dl (range, 640 to 920 mg/dl) between 24 and 48 hours after administration of IgG. Foals of this group had mean body weight of 43.2 kg (range, 36.5 to 47.5 kg). Serum IgG concentration in group-2 foals at 24 to 48 hours was significantly (P = 0.005) greater than that in group-1 foals. Mean total IgG recovery at 24 to 48 hours, calculated on the basis of 94.5 ml of plasma volume/kg of body weight, was approximately 100%. Values of IgG measured in all foals 1 and 2 weeks after administration of the IgG concentrate were equivalent to values expected after normal decay of passively acquired IgG. Mild, adverse reactions occurred in 3 of the treated (1 group-1 foal and 2 group-2 foals).

The cardiovascular effects of xylazine and detomidine in horses were studied. Six horses were Liven each of the following 5 treatments, at 1-week intervals: xylazine, 1.1 mg/kg, IV; xylazine, 2.2 mg/kg, IM; detomidine, 0.01 mg/kg, IV; detomidine, 0.02 mg/kg, IV; and detomidine, 0.04 mg/kg, IM. All treatments resulted in significantly decreased heart rate, increased incidence of atrioventricular block, and decreased cardiac output and cardiac index; cardiac output and cardiac index were lowest following IV administration of 0.02 mg of detomidine/kg. Mean arterial pressure was significantly reduced for various periods with all treatments; however, IV administration of 0.02 mg of detomidine/kg caused hypertension initially. Systemic vascular resistance was increased by all treatments. Indices of ventricular contractility and relaxation, + dP/dt and - dP/dt, were significantly depressed by all treatments. Significant changes were not detected in stroke volume or ejection fraction. The PCV was significantly reduced by all treatments. Respiratory rate was significantly decreased with all treatments, but arterial carbon dioxide tension did not change. Arterial oxygen tension was significantly decreased briefly with the 3 IV treatments only.

Axial length and corneal curvature were determined by use of A-scan ultrasonography and keratometry on both eyes of dogs of various breeds, sizes, and ages. Mean axial length was 20.43 +/- 1.48 mm; axial length was not related to age or sex, but was significantly greater (P = 0.047) in dogs of larger breeds. Mean corneal curvature was 39.94 +/- 2.61 diopters. Dogs of large breeds had significantly (P < 0.001) flatter corneas. Mild, roughly symmetric astigmatism was detected in a majority of dogs. Use of mean values in a theoretic artificial intraocular lens power equation suggests that aphakic dogs require an implant of approximately 40 diopters to achieve emmetropia.

The effects of single IV injections of sodium bicarbonate (0.5 mEq/kg of body weight, 1 mEq/kg, 2 mEq/kg, and 4 mEq/kg) on serum osmolality, serum sodium, chloride, and potassium concentrations, and venous blood gas tensions in 6 healthy cats were monitored for 180 minutes. Serum osmolality increased and remained significantly (P less than 0.05) increased for 120 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium was increased significantly (P less than 0.05) for 30 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium decreased and remained significantly (P less than 0.05) decreased for 120 minutes in cats given 1 g of 20% mannitol/kg, and serum osmolality was significantly (P less than 0.05) decreased at 30 and 60 minutes. Serum chloride decreased significantly (P less than 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and was significantly decreased for 30 minutes in cats given 2 mEq and 4 mEq of sodium bicarbonate/kg. Serum chloride decreased and remained significantly (P less than 0.05) decreased for 30 minutes in cats given 1 g of 20% mannitol/kg. Serum sodium and serum osmolality did not change significantly (P less than 0.05) in cats given 4 ml of 0.9% sodium chloride/kg. Serum potassium decreased significantly (P less than 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and for 120 minutes in cats given 2 mEq/kg or 4 mEq/kg. There was a significantly (P less than 0.05) greater decrease in serum potassium that lasted for 30 minutes after giving sodium bicarbonate at the dosage of 4 mEq/kg, compared with other dosages given. Serum potassium did not change significantly in cats given 1 g of 20% mannitol/kg, but was significantly (P less than 0.05) decreased 10 minutes following 4 ml of 0.9% sodium chloride/kg. Sodium bicarbonate infusion significantly (P less than 0.05) increased venous blood pH and plasma bicarbonate concentration in all cats. The magnitude and duration of these changes were significantly greater following administration of sodium bicarbonate at dosages of 2 mEq/kg and 4 mEq/kg. Significant (P less than 0.05) increases in PCO2 were associated only with the highest dosage of sodium bicarbonate (4 mEq/kg). Base excess increased significantly (P less than 0.05) in all cats following sodium bicarbonate infusion. There were significantly (P less than 0.05) greater increases in base excess lasting 30 minutes following administration of sodium bicarbonate at dosages of 2 mEq/kg and 4 mEq/kg. Significant (P less than 0.05) changes in venous blood pH, PCO2, or bicarbonate were not observed in cats given 4 ml of 0.9% sodium chloride/kg, or in cats given 1 g of 20% mannitol/kg. Base excess was significantly (P less than 0.05) increased for 10 minutes in cats given 1 g of 20% mannitol/kg. As expected, 4 mEq of sodium bicarbonate/kg induced the most time- and dosage-related effects. Caution should be used when administering sodium bicarbonate IV to cats at dosages greater than 2 mEq/kg, because of the potential for important acid-base and electrolyte changes.

Serum glucose and immunoreactive insulinconcentrations were monitored after topical administration of an insulin-containing ophthalmic solution in 20 clinically normal cats. Three ophthalmic surface-acting agents, benzalkonium chloride, dimethyl sulfoxide, and proparacaine hydrochloride, were evaluated individually for their effectiveness in enhancing absorption of topically applied insulin. The ophthalmic effects of insulin-containing ophthalmic preparations were assessed by complete ophthalmic examination before and at the conclusion of each test period. Withholding of food overnight (12 hours) preceded each topical application of insulin-containing ophthalmic solution (12.25 to 26.4 U/cat), either alone or in combination with surface-acting agents, after which blood samples were drawn serially from an indwelling IV catheter over a period of 8 hours. Baseline serum insulin concentration, after food was withheld for 12 hours, in nonstressed cats was 6.0 microunit/ml (geometric mean), and an exponentiation of the logarithmic quantity (mean +/- SD) yielded values of 1.5 to 23.0 microunit/ml. All ophthalmicsolutions tested failed to significantly lower serum glucose concentration or increase serum insulin concentration. Solutions used did not induce deleterious effect on ocular structures. Results indicate that topical administration of insulin-containing ophthalmic solution, either alone at the concentrations used or in combination with surface-acting agents, did not result in effective absorption of insulin across the conjunctival and lacrimal nasal mucosa in biologically relevent quantities. Thus, this route of insulin administration, under these specific conditions, is not an effective alternative or adjunct to SC administration of insulin for treatment of cats with insulin-dependent diabetes mellitus or severe noninsulin-dependent diabetes mellitus.

Fetal activity and mobility and changes in diameter of the allantoic fluid compartment in the uterine horns were studied in mares between days 69 and 81 of pregnancy by use of transrectal ultrasonography (n = 12) and transcervical videoendoscopy (n = 8). The insertion tube of the videoendoscope was positioned within the allantoic sac to permit viewing of the fetus and entrance to each uterine horn. Each uterine horn was divided ultrasonographically into 3 segments of equal length, and the horns were designated on the basis of side of umbilical attachment (cord vs noncord horns). The diameter of the allantoic fluid compartment in the cornual segments increased (P < 0.05) over the cranial (18.6 +/- 1.9 mm), middle (35.6 +/- 2.9 mm), and caudal (51.7 +/- 4.4 mm) segments, but differences between cord and noncord horns were not evident. Dynamic changes in diameter of the allantoic fluid compartment in cornual segments (ultrasonography) and at the entrance to each uterine horn (videoendoscopy) were detected (no significant difference between methods). During continuous videoendoscopic viewing (17 to 60 min/mare), extreme changes in allantoic fluid compartment diameter (76 to 100% of maximum to 0 to 25% of maximum or vice-versa) occurred an equivalent of 2.6 times/h/horn entrance; changes had an average duration of 3.4 minutes. A change from 100% (maximal diameter) to 0% (no visible lumen) or vice-versa occurred an equivalent of 1.3 times/h/horn entrance. Sometimes the uterine wall was so closely constricted around the fetal-amniotic unit that no intervening allantoic fluid was ultrasonographically detectable, whereas at other times, the uterus in the same location was widely dilated. Results indicated that extensive allantoic fluid shifts were associated with frequent diameter changes in various segments of the uterus. On the basis of 30-second activity trials every 10 minutes, the fetus was active 27% and was quiet 73% of the time (combined ultrasonographic and videoendoscopic data). Activity sometimes involved only movements of extremities, head, or mouth, whereas at other times, a sudden burst of intense whole-body activity was observed. The vigorous whole-body movements buoyed the fetus into the allantoic fluid, and movements of the extremities often caused the fetus to push away from the allantoic wall, resulting in marked changes in location, recumbency, and presentation (direction faced by fetus). Several instances were observed during videoendoscopic examination, in which the fetal-amniotic unit appeared to be forced through a constricted horn entrance into the allantoic fluid compartment at the dilated uterine body. On the basis of continuous videoendoscopic viewing, the fetus changed locations among the major portions of the uterus (body and each horn), on average, 5.0 times/h. Changes in recumbency and presentation occurred, on average, 10.5 and 5.0 times/h, respectively. The frequency of type of recumbency decreased (P < 0.005) as follows: lateral, 23 of 39 (59%); dorsal, 15 of 39 (38%); and ventral, 1 of 39 (3%). Frequency of cranial, caudal, and transverse presentation was not different between cord and noncord horn. Caudal presentation was more common (P < 0.005) when the fetus was in a uterine horn (47/70, 67%) than when it was in the uterine body (15/50, 30%; combined ultrasonographic and videoendoscopic data). Transverse presentation was more common (P < 0.005) when the fetus was in the uterine body (14/50, 28%) than when it was in a horn (4/70, 6%). Results indicated that the early stage equine fetus (days 69 to 81) is extremely mobile within the allantoic fluid, with frequent (several times per hour) changes in location, recumbency, and presentation.