Objective--To determine whether joint lavage performed simultaneously with IV regional limb perfusion (IVRLP) reduces the effectiveness of IVRLP and to compare 2 types of tourniquets used for this procedure in horses. Animal--11 adult horses. Procedures--2 groups of 6 horses were tested by use of a pneumatic or an Esmarch tourniquet (1 horse was tested twice [once in each group]). Standing IVRLP with amikacin (500 mg) was performed for 30 minutes. Simultaneously, the metacarpophalangeal joint was lavaged with 2 L of lactated Ringer's solution and the egress fluids were collected. Samples of the distal interphalangeal joint synovial fluid and blood from the digital and jugular veins were collected at set time intervals. Amikacin concentrations in all fluids were determined via fluorescence polarization immunoassay. Results--Less amikacin was measured in the systemic circulation with the Esmarch tourniquet than with the pneumatic tourniquet. Amikacin concentrations in the synovial fluid from the distal interphalangeal joints of the Esmarch tourniquet group ranged from 45.1 to 1,968 μg/mL and in the pneumatic tourniquet group ranged from 1.7 to 92.3 μg/mL after 30 minutes of IVRLP. Total loss of amikacin in the egress fluids from the joint lavage ranged from < 1.36 to 7.72 mg for the Esmarch tourniquet group and from < 1.20 to 1.75 mg for the pneumatic tourniquet group. Conclusions and Clinical Relevance--On standing horses, IVRLP performed simultaneously with joint lavage resulted in negligible loss of amikacin in the egress lavage fluids. The Esmarch tourniquet was more effective in preventing loss of amikacin from the distal portion of the limb, easier to use, and less expensive than the pneumatic tourniquet.

Objective—To determine whether trilostane or ketotrilostane is more potent in dogs and determine the trilostane and ketotrilostane concentrations that inhibit adrenal gland cortisol, corticosterone, and aldosterone secretion by 50%. Sample—24 adrenal glands from 18 mixed-breed dogs. Procedures—Adrenal gland tissues were sliced, placed in tissue culture, and stimulated with 100 pg of ACTH/mL alone or with 5 concentrations of trilostane or ketotrilostane. Trials were performed independently 4 times. In each trial, 6 samples (1 for each time point) were collected for each of the 5 concentrations of trilostane and ketotrilostane tested as well as a single negative control samples. At the end of 0, 1, 2, 3, 5, and 7 hours, tubes were harvested and media and tissue slices were assayed for cortisol, corticosterone, aldosterone, and potassium concentrations. Data were analyzed via pharmacodynamic modeling. One adrenal slice exposed to each concentration of trilostane or ketotrilostane was submitted for histologic examination to assess tissue viability. Results—Ketotrilostane was 4.9 and 2.4 times as potent in inhibiting cortisol and corticosterone secretion, respectively, as its parent compound trilostane. For trilostane and ketotrilostane, the concentrations that inhibited secretion of cortisol or corticosterone secretion by 50% were 480 and 98.4 ng/mL, respectively, and 95.0 and 39.6 ng/mL, respectively. Conclusions and Clinical Relevance—Ketotrilostane was more potent than trilostane with respect to inhibition of cortisol and corticosterone secretion. The data should be useful in developing future studies to evaluate in vivo serum concentrations of trilostane and ketotrilostane for efficacy in the treatment of hyperadrenocorticism.

Objective—To determine ocular tissue drug concentrations after topical ocular administration of 0.3% ciprofloxacin and 0.5% moxifloxacin in ophthalmologically normal horses. Animals—24 ophthalmologically normal adult horses. Procedures—0.3% ciprofloxacin and 0.5% moxifloxacin solutions (0.1 mL) were applied to the ventral conjunctival fornix of 1 eye in each horse as follows: group 1 (n = 8) at 0, 2, 4, and 6 hours; group 2 (8) at 0, 2, 4, 6, and 10 hours; and group 3 (8) at 0, 2, 4, 6, 10, and 14 hours. Tears, cornea, and aqueous humor (AH) were collected at 8, 14, and 18 hours for groups 1, 2, and 3, respectively. Drug concentrations were determined via high-performance liquid chromatography. Results—Median (25th to 75th percentile) concentrations of ciprofloxacin for groups 1, 2, and 3 in tears (μg/mL) were 53.7 (25.5 to 88.8), 48.5 (19.7 to 74.7), and 24.4 (15.4 to 67.1), respectively; in corneal tissue (μg/g) were 0.95 (0.60 to 1.02), 0.37 (0.32 to 0.47), and 0.48 (0.34 to 0.95), respectively; and in AH were lower than the limit of quantification in all groups. Concentrations of moxifloxacin for groups 1, 2, and 3 in tears (μg/mL) were 188.7 (44.5 to 669.2), 107.4 (41.7 to 296.5), and 178.1 (70.1 to 400.6), respectively; in corneal tissue (μg/g) were 1.84 (1.44 to 2.11), 0.78 (0.55 to 0.98), and 0.77 (0.65 to 0.97), respectively; and in AH (μg/mL) were 0.06 (0.04 to 0.08), 0.03 (0.02 to 0.05), and 0.02 (0.01 to 0.04), respectively. Corneal moxifloxacin concentrations were significantly higher in group 1 than groups 2 and 3. Conclusions and Clinical Relevance—After topical ocular administration, fluoroquinolones can reach therapeutic concentrations in tears and corneal tissue of horses, even when there is an intact epithelium.

Objective—To evaluate the ability of 2-D time-of-flight (ToF) magnetic resonance angiography (MRA) to depict intracranial vasculature and compare results obtained with 3.0- and 7.0-T scanners in dogs. Animals—5 healthy Beagles. Procedures—2-D ToF-MRA of the intracranial vasculature was obtained for each dog by use of a 3.0-T and a 7.0-T scanner. Quantitative assessment of the images was obtained by documentation of the visibility of major arteries comprising the cerebral arterial circle and their branches and recording the number of vessels visualized in the dorsal third of the brain. Qualitative assessment was established by evaluation of overall image quality and image artifacts. Results—Use of 3.0- and 7.0-T scanners allowed visualization of the larger vessels of the cerebral arterial circle. Use of a 7.0-T scanner was superior to use of a 3.0-T scanner in depiction of the first- and second-order arterial branches. Maximum-intensity projection images had a larger number of vessels when obtained by use of a 7.0-T scanner than with a 3.0-T scanner. Overall, image quality and artifacts were similar with both scanners. Conclusions and Clinical Relevance—Visualization of the major intracranial arteries was comparable with 3.0- and 7.0-T scanners; the 7.0-T scanner was superior for visualizing smaller vessels. Results indicated that ToF-MRA is an easily performed imaging technique that can be included as part of a standard magnetic resonance imaging examination and should be included in the imaging protocol of dogs suspected of having cerebrovascular disease.

Objective—To compare the bone temperature and final hole dimensions associated with sequential overdrilling (SO) and single 6.2-mm drill bit (S6.2DB) methods used to create transcortical holes in the third metacarpal bones (MCIIIs) of horse cadavers. Sample—60 MCIIIs from 30 horse cadavers. Procedures—In phase 1, hole diameter, tap insertion torque, peak bone temperature, and postdrilling bit temperature for 6.2-mm-diameter holes drilled in the lateral or medial cortical region of 12 MCIIIs via each of three 2-bit SO methods with a single pilot hole (diameter, 3.2, 4.5, or 5.5 mm) and the S6.2DB method were compared. In phase 2, 6.2-mm-diameter transcortical holes were drilled via a 2-bit SO method (selected from phase 1), a 4-bit SO method, or a S6.2DB method at 1 of 3 locations in 48 MCIIIs; peak bone temperature during drilling, drill bit temperature immediately following drilling, and total drilling time were recorded for comparison. Results—Hole diameter or tap insertion torque did not differ among phase 1 groups. Mean ± SD maximum bone temperature increases at the cis and trans cortices were significantly less for the 4-bit SO method (3.64 ± 2.01°C and 8.58 ± 3.82°C, respectively), compared with the S6.2DB method (12.00 ± 7.07°C and 13.19 ± 7.41°C, respectively). Mean drilling time was significantly longer (142.9 ± 37.8 seconds) for the 4-bit SO method, compared with the S6.2DB method (49.7 ± 24.3 seconds). Conclusions and Clinical Relevance—Compared with a S6.2DB method, use of a 4-bit SO method to drill transcortical holes in cadaveric equine MCIIIs resulted in smaller bone temperature increases without affecting hole accuracy.

Objective—To compare secretory responses to prostaglandin (PG) E2 in mucosa obtained from the proximal and distal portions of the colon of dogs. Sample—Colonic mucosa from cadavers of 18 clinically normal adult dogs. Procedures—Short-circuit current (ISC) and maximum change in ISC (ΔIsc) in response to administration of 1μM PGE2 were measured across mucosa obtained from the proximal and distal portions of the colon. Responses were evaluated in mucosa (n = 6 dogs) incubated in Ussing chambers with or without 1 mM amiloride or without chloride in the Ringer's bathing solution. Responses were also evaluated in mucosa (n = 9 dogs) incubated with or without pretreatment with 1 μM indomethacin, with or without amiloride in the subsequent bathing solution. Histologic changes in mucosa from 3 dogs were assessed over time. Results—ISC and ΔISC were significantly reduced when chloride was removed from, but not when amiloride was added to, the bathing solution and were significantly reduced after pretreatment with indomethacin. The ΔISC was significantly greater in mucosa from the distal portion of the colon than in the proximal portion of the colon. Histologic changes after incubation for 3 hours were minimal. Conclusions and Clinical Relevance—ISC and ΔISC resulted from electrogenic chloride secretion. Chloride secretion was reduced when release of PGs was prevented by indomethacin and was induced by administration of PGE2. Chloride secretion in response to PGE2 was greater in mucosa from the distal portion of the colon than in mucosa from the proximal portion of the colon.

The interaction of Bordetella bronchiseptica, toxigenic Pasteurella multocida serotype D, and the mycotoxin fumonisin B1 (FB1) was studied. On day 0 of the experiment, 28 artificially reared 3-day-old piglets were divided into 4 groups (n = 7 each): a control group (A), a group fed FB1 toxin (B), a group infected with the 2 pathogens (C), and a group infected with the 2 pathogens and fed FB1 toxin (D). The B. bronchiseptica infection [with 106 colony-forming units (CFU)/mL] was performed on day 4 and the P. multocida infection (with 108 CFU/mL) on day 16. From day 16 a Fusarium verticillioides fungal culture (dietary FB1 toxin content 10 mg/kg) was mixed into the feed of groups B and D. In groups C and D, clinical signs including mild serous nasal discharge, sneezing, panting, and hoarseness appeared from day 4, and then from day 16 some piglets had coughing and dyspnea as well. Computed tomography (CT) performed on day 16 demonstrated lung lesions attributable to colonization by B. bronchiseptica in the infected groups. By day 25 the number of piglets exhibiting lesions had increased, and the lesions appeared as well-circumscribed, focal changes characterized by a strong density increase in the affected areas of the lungs. The gross pathological findings confirmed the results obtained by CT. These results indicate that, when combined with dual infection by B. bronchiseptica and P. multocida, dietary exposure of pigs to FB1 toxin raises the risk of pneumonia and increases the extent and severity of the pathological changes.

Changes in luteinizing hormone (LH) secretion after 17beta-estradiol (E2) injection were evaluated during sexual maturation in 10 prepubertal Nelore heifers. Heifers were divided into 2 groups: intact (I) and ovariectomized (OVX). 17beta-estradiol (2 micrograms/kg) was administered to both groups at 10, 13, and 17 mo of age. Only at 10 mo of age was there a greater mean LH concentration in OVX heifers (1.33 +/- 0.29 ng/mL) compared with the I group (0.57 +/- 0.15 ng/mL). At 13 and 17 mo of age there was no significant difference between the 2 groups in any of the evaluated variables (number of peaks, total peak area, greatest peak area, and time to greatest peak occurrence). This suggests a decrease in negative E2 feedback associated with an increase in positive feedback to LH secretion during sexual maturation, and these were likely the key factors that determined the time of first ovulation in Nelore heifers.

Little work has been conducted on the helminth parasites of artiodactylids in the northern and western parts of the Limpopo province, which is considerably drier than the rest of the province. The aim of this study was to determine the kinds and numbers of helminth that occur in different wildlife hosts in the area as well as whether any zoonotic helminths were present. Ten impalas (Aepyceros melampus), eight kudus (Tragelaphus strepsiceros), four blue wildebeest (Connochaetes taurinus), two black wildebeest (Connochaetes gnou), three gemsbok (Oryx gazella), one nyala (Tragelaphus angasii), one bushbuck (Tragelaphus scriptus), one waterbuck (Kobus ellipsiprymnus), six warthogs (Phacochoerus aethiopicus) and a single bushpig (Potamochoerus porcus) were sampled from various localities in the semi-arid northern and western areas of the Limpopo province. New host–parasite associations included Trichostrongylus deflexus from blue wildebeest, Agriostomum gorgonis from black wildebeest, Stilesia globipunctata from the waterbuck and Fasciola hepatica in a kudu. The mean helminth burden, including extra-gastrointestinal helminths, was 592 in impalas, 407 in kudus and blue wildebeest, 588 in black wildebeest, 184 in gemsbok, and 2150 in the waterbuck. Excluding Probstmayria vivipara, the mean helminth burden in warthogs was 2228 and the total nematode burden in the bushpig was 80. The total burdens and species richness of the helminths in this study were consistently low when compared with similar studies on the same species in areas with higher rainfall. This has practical implications when animals are translocated to areas with higher rainfall and higher prevalence of helminths.

Despite a large number of studies on tick biology, there is limited information on long- term changes in tick populations. This study thus aimed to assess the long-term population dynamics of questing ixodid ticks in two landscape zones of the Kruger National Park (KNP). Questing ixodid ticks were collected in the KNP from August 1988 to March 2002 by monthly dragging of the vegetation in three habitats (grassland, woodland and gully) at two sites (Nhlowa Road and Skukuza). Findings pertaining to total tick numbers and Amblyomma hebraeum and Rhipicephalus decoloratus specifically are presented here. Fourteen tick species were collected, as well as four others that could be identified only to generic level. More ticks (211 569 vs 125 810) were collected at Nhlowa Road than at Skukuza. Larvae were the most commonly collected stage of all the major tick species. A. hebraeum was the most commonly collected tick (63.6%) at Nhlowa Road, whereas R. decoloratus accounted for 15.3% of the ticks collected there. At Skukuza, 31.6% and 27.1% of the collected ticks were R. decoloratus and A. hebraeum respectively. Most A. hebraeum larvae were collected in summer and the fewest in winter and early spring, mostly in woodland and least often in grassland habitats. Most R. decoloratus larvae were collected in spring and the fewest in autumn and winter, and were more frequently collected in woodland and grassland than in gullies. The largest collections of most tick species were made during the early 1990s, while numbers were lowest in the mid-1990s after a drought during 1991 and 1992 and then increased towards the late 1990s, followed by a final decrease. The changes in tick numbers over time probably reflect differences in their host communities at the two sites and the effect of climatic conditions on both hosts and free-living ticks. The population dynamics of questing ticks reflect a complex interaction between ticks, their hosts and the environment.