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  • Author or Editor: Gordon W. Brumbaugh x
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in Journal of the American Veterinary Medical Association

SUMMARY

Samples of pleural fluid from 20 horses with effusive pleural diseases of various causes were evaluated; samples from 19 horses were used for the study. There were differences for pH (P = 0.001) and partial pressure of oxygen (Po2 ) between arterial blood and nonseptic pleural fluid (P = 0.0491), but there were no differences for pH, Po2 , partial pressure of carbon dioxide (Pco2 ), and concentrations of bicarbonate (HCO3 -), lactate, and glucose between venous blood and nonseptic pleural fluid. Paired comparisons of venous blood and nonseptic pleural fluid from the same horse indicated no differences.

There were differences (P = 0.0001, each) for pH, Po2 , Pco2 , and concentrations of HCO3 - between arterial blood and septic pleural fluid. Differences also existed for pH (P = 0.0001), Pco2 (P = 0.0003), and concentrations of HCO3 - (P = 0.0001), lactate (P = 0.0051), and glucose (P = 0.0001) between venous blood and septic pleural fluid. Difference was not found for values of Po2 between venous blood and septic pleural fluid, although 4 samples of septic pleural fluid contained virtually no oxygen. Paired comparisons of venous blood and septic pleural fluid from the same horse revealed differences (P < 0.05) for all values, except those for Po2 .

These alterations suggested functional and physical compartmentalization that separated septic and healthy tissue. Compartmentalization and microenvironmental factors at the site of infection should be considered when developing therapeutic strategies for horses with septic pleural disease.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether a unique dihydropyridine (BAY TG 1000) would be beneficial in preventing laminitis in horses.

Animals—16 clinically normal adult horses.

Procedure—8 pairs of horses were used in a controlled double-blind study, using sex- and agematched horses randomly assigned to treatment or control groups. Horses were subjected to carbohydrate overload to induce laminitis. Treated horses were administered BAY TG 1000 (30 mg/kg, PO, q 24 h) for 3 days. Hoof wall surface temperature (HWST) and lameness were recorded at 4-hour intervals. The HWST was adjusted on the basis of time of onset of lameness and evaluated, using a repeated-measures ANOVA. Lameness 8 hours after onset and clinical status 72 hours after onset of lameness were evaluated, using Mann-Whitney procedures.

Results—Analysis revealed that BAY TG 1000 did not decrease the incidence of lameness but significantly ameliorated prodromal hypothermia, lessened the severity of lameness 8 hours after onset of lameness, and improved the clinical status of horses 72 hours after onset of lameness.

Conclusion and Clinical Relevance—Results support the conclusion that BAY TG 1000 was protective when used in prevention of laminitis. The drug decreased severity and improved clinical status (recovery) of induced lameness, which was interpreted to mean that the drug's actions were on mechanisms important but secondary to primary causal mechanisms of laminitis. Therefore, drugs that enhance digital perfusion via alteration of rheologic activity may have potential use in the prevention and management of laminitis in horses. (Am J Vet Res 2002;63:443–447)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the use of hoof wall surface temperature (HWST) as an indirect indicator of digital perfusion and to describe HWST patterns during the prodromal and acute phases of carbohydrate-induced laminitis in horses.

Animals—30 adult horses without foot abnormalities.

Procedures—Three experiments were performed. In the first, HWST was measured in 2 groups of horses acclimatized to hot (n = 6), or cold (6) environments and exposed to cold (15 C) ambient temperature. In the second experiment, HWST were measured in both forefeet of 6 horses before and after application of a tourniquet to 1 forefoot to induce vascular occlusion. In the third experiment, HWST were recorded in 12 horses before and during the prodromal and acute phases of carbohydrate-induced laminitis.

Results—Mean HWST of hot-acclimatized cold-challenged horses was significantly less than that of cold-acclimatized cold-challenged horses at all times. Transient episodes of high HWST were observed during prolonged cold-induced vasoconstriction. Hoof wall surface temperature significantly decreased during arterial occlusion and increased during reperfusion. Digital hypothermia was observed during the prodromal phase of carbohydrate-induced laminitis.

Conclusions and Clinical Relevance—Determination of HWST is a valid technique to evaluate digital perfusion under appropriate controlled conditions in horses. Digital hypothermia detected during the prodromal phase of laminitis is consistent with decreased digital vascular perfusion or metabolic activity. If administered to horses during the prodromal phase, agents that enhance digital perfusion may prevent development of laminitis. (Am J Vet Res 2001; 62:1167–1172)

Full access
in American Journal of Veterinary Research

SUMMARY

Full-thickness, circular (4-cm diameter) cutaneous wounds were created on the metacarpi and metatarsi of 6 horses. Immediately after wounding, 1 wound on each horse received a meshed, split-thickness skin graft (0.64 mm) obtained from the ventrolateral aspect of the horse's thorax by use of a pneumatic dermatome, whereas a second wound received a meshed, full-thickness skin graft obtained from the pectoral area. In addition, sections of split-thickness and full-thickness grafts were refrigerated in a solution of McCoy's 5A medium, to which equine serum (10%) and gentamicin sulfate solution (16 mg/dl) were added. Ten days after wounding, 1 granulating wound on each horse was grafted with a stored, meshed, split-thickness graft, and 1 granulating wound on each horse was grafted with a stored, meshed, full-thickness graft.

Areas of wounds were calculated from photographs taken of wounds on days 1, 5, 10, 15, 20, 25, and 30 after wounding. Time course of contraction was determined by use of a first-order mathematic model of changes in area through time.

Rate constants of contraction for fresh or granulating wounds receiving full-thickness grafts did not differ signficantly from those for fresh or granulating wounds receiving split-thickness grafts. Rate constants of contraction for grafted fresh wounds, however, were significantly less than those of grafted granulating wounds, regardless of whether a split-thickness or full-thickness graft was applied.

Free access
in American Journal of Veterinary Research

SUMMARY

Full-thickness, circular, cutaneous wounds (5 cm in diameter) were created on the distal portion of the forelimbs of 6 horses. One wound on each horse was treated with 6 full-thickness punch grafts that were obtained from the horse's neck with a 6-mm skin biopsy punch and inserted in the graft sites on day 14 after wounding. The wound on the contralateral limb was not grafted. A combination of ticarcillin disodium and clavulanate potassium was applied to the wounds when bandages were changed to control bacterial infection. Areas of each wound were measured on days 1, 7, 9, 11, 13 through 15, 17 through 22, 24, 26, 29, and 32 after wounding. Three distinguishable phases of healing were observed (expansion, contraction, and epithelialization), and the time course of each phase was evaluated, using formulas of first-order processes. Rate constants of each phase were not significantly (P < 0.05) affected by punch grafts.

Free access
in American Journal of Veterinary Research

Summary

Six Jersey cows were implanted with 8 pairs of bipolar electrodes: 1 in the jejunum, 1 in the ileum, 3 in the cecum, and 3 in the proximal loop of the ascending colon (plac). Myoelectric activity was recorded at 2- to 3-day intervals, 3 times for 8 hours or 4 times for 6 hours, using a computer-based oscillograph and data-acquisition program.

Mean (± sd) duration of the migrating myoelectric complex (mmc) in the ileum was 84.52 ± 4.87 minutes. Phases I and II of the mmc lasted significantly (P < 0.05) longer than phase III. Two types (A and B) of cyclic activity were found in the cecum and plac. Cyclic activity type A was observed predominantly in the cecum, and type B was observed exclusively in the plac. Phase III of the mmc in the ileum was accompanied by hyperactivity type A at the level of the ileocecocolic junction in 60.90 ± 12.65% of the mmc. Twenty-seven types of orally and aborally propagated spike sequences, involving the cecum and plac, were found. They were most frequent when an mmc phase III was observed in the ileum, and least frequent when an mmc phase I was observed in the ileum (P < 0.05). All electrode sites of the cecum and plac served as pacemaker areas. Propagated and nonpropagated spikes were found at all electrode sites of the cecum and plac. Although propagated spikes lasted significantly (P < 0.05) longer than nonpropagated spikes, a clear distinction on the basis of duration could not be defined between the 2 spike types because broad overlapping of duration existed. Duration of cecocolic spiking activity per electrode (expressed as percentage of time) was significantly (P < 0.05) greater during mmc phase III in the ileum than during mmc phase I.

It can be concluded that myoelectric activity of the cecum is well coordinated with the ileum and the plac. Phases of reduced and increased myoelectric activity in the cecum and plac are simultaneous with phases I and III of the mmc in the ileum.

Free access
in American Journal of Veterinary Research

Summary

Opsonized Rhodococcus equi activated the respiratory burst of resident alveolar macrophages (am) from adult horses in a logarithmic-linear, mass-related manner. The effect of R equi was not significantly different from that of equal masses of opsonized zymosan A. Therefore, R equi does not appear to attenuate the respiratory burst of equine am. The stimulatory effect of R equi was not reflected by increased production of superoxide anion (O2 -), but increased activity of the hexose monophosphate shunt was observed. These results suggest a similarity between the respiratory burst of am from horses and that of am from rabbits. We concluded that resident am from adult horses do not produce O2 - concurrently with an increase in activity of the hexose monophosphate shunt when stimulated with either opsonized zymosan A or opsonized R equi. This suggests that O2 - is not an important component of the antibacterial defenses of equine am. Whether equine am are incapable of producing O2 - or require different stimuli to produce it was not determined.

Free access
in American Journal of Veterinary Research

Abstract

Objectives—To compare limb-load distribution between horses with and without acute or chronic laminitis.

Animals—10 horses with carbohydrate-induced acute laminitis, 20 horses with naturally occurring chronic laminitis, and 20 horses without foot abnormalities (controls).

Procedures—Limb-load distribution was determined, using a custom-designed system that allowed simultaneous quantification of the mean percentage of body weight voluntarily placed on each limb (ie, mean limb load) and the SD of the mean load over a 5- minute period (ie, load distribution profile [LDP]). Load distribution profile was used as an index of frequency of load redistribution.

Results—Mean loads on fore- and hind limbs in control horses were 58 and 42%, respectively, and loads were equally and normally distributed between left and right limbs. In addition, forelimb LDP was greater, compared with hind limbs, and was affected by head and neck movement. In comparison, limb-load distribution in horses with chronic laminitis was characterized by an increase in the preferential loading of a forelimb, a decrease in total forelimb load, and an increase in LDP that was correlated with severity of lameness. In horses with carbohydrate-induced acute laminitis, mean limb loads after onset of lameness were not different from those prior to lameness; however, LDP was significantly decreased after onset of lameness.

Conclusion and Clinical Relevance—Quantification of limb-load distribution may be an applicable screening method for detecting acute laminitis, grading severity of lameness, and monitoring rehabilitation of horses with chronic laminitis. (Am J Vet Res 2001; 62:1393–1398)

Full access
in American Journal of Veterinary Research