Ventilatory and Metabolic Compensation in Dogs With Acid-Base Disturbances

Ventilatory and metabolic compensation to acid-base disturbances is reviewed. The mechanisms for compensation as well as the values obtained from several studies using normal dogs and dogs with experimentally induced diseases are provided. Compensation is not the same in dogs and human beings. Dogs have a better ability to adapt to most respiratory disorders, and human beings adapt better to metabolic acidosis. In metabolic alkalosis and chronic respiratory acidosis there is no difference in compensation between these species. Ventilatory compensation for metabolic disorders in dogs is the same whether they have metabolic acidosis or metabolic alkalosis, whereas metabolic compensation in respiratory disturbances is less effective in acidosis. Values for the expected changes in PCO₂ in dogs with metabolic acidosis and metabolic alkalosis, and for bicarbonate concentration (HCO₃-) in dogs with acute and chronic respiratory alkalosis and acidosis are presented.     

Hormonal changes and follicular activity after treatment with intravaginal progesterone‐releasing devices in llamas

Plasma progesterone (P₄) concentrations and follicular activity after administration of different P₄ doses were evaluated in 33 adult female llamas treated with intravaginal devices. In Study 1, a group of llamas (n = 10) was treated with an intravaginal device (IVD) containing 160 (n = 5) or 780 mg of P₄ (n = 5). Based on the results from the first study, in Study 2, females with follicles at different stages of development were treated with the IVD containing 780 mg of P₄ (n = 21) or remain untreated (control; n = 12) to evaluate the effect of P₄ on follicular activity. In Study 1, the IVD containing 160 mg of P₄ induced follicular turnover in 60% of females while the remaining 40% of llamas developed persistent follicles. Thus, this device controlled follicular activity in llamas, although it promotes the persistence of follicles present at start of treatment. Conversely, in both studies, the IVD containing 780 mg of P₄ suppressed follicular development and hasten the emergence of a new follicular wave in all females regardless of the follicular phase at insertion. Additionally, in Study 2, this device effectively concentrated the appearance of follicles with ovulatory diameter at a definite time after treatment in comparison with control animals. In conclusion, treatment with an IVD containing 780 mg of P₄ would be considered for the control of follicular activity in llamas as it ensures the presence of a young follicle with ovulatory diameter by day 6 after the end of treatment in all females.     

Magnetic resonance spectroscopy of the canine brain at 3.0 T and 7.0 T

The purpose of this study was to evaluate the feasibility of proton magnetic resonance spectroscopy (1H MRS) to study the concentration of metabolites in the brain of dogs at 3.0 and 7.0 T. Four healthy male beagles were scanned using 3.0 T and 7.0 T human magnetic resonance imaging (MRI) units. The results obtained showed that all dogs had excellent quality spectra for a small (1 cm3) and large (8 cm3) voxel at 3.0 T, whereas only 2 dogs had high quality spectra at 7.0 T due to insufficient water suppression. 1H MRS at 3.0 T appears to be a reliable method to study metabolite concentrations in the canine brain. The development of more advanced water suppression techniques is necessary to improve the results at 7.0 T.     

Effect of lidocaine on the minimum alveolar concentration of sevoflurane in dogs

Objective  To investigate the effects of a low-dose constant rate infusion (LCRI; 50 μg kg⁻¹ minute⁻¹) and high-dose CRI (HCRI; 200 μg kg⁻¹ minute⁻¹) lidocaine on arterial blood pressure and on the minimum alveolar concentration (MAC) of sevoflurane (Sevo), in dogs.
Study design  Prospective, randomized experimental design.
Animals  Eight healthy adult spayed female dogs, weighing 16.0 ± 2.1 kg.
Methods  Each dog was anesthetized with sevoflurane in oxygen and mechanically ventilated, on three separate occasions 7 days apart. Following a 40-minute equilibration period, a 0.1-mL kg⁻¹ saline loading dose or lidocaine (2 mg kg⁻¹ intravenously) was administered over 3 minutes, followed by saline CRI or lidocaine LCRI or HCRI. The sevoflurane MAC was determined using a tail clamp. Heart rate (HR), blood pressure and plasma concentration of lidocaine were measured. All values are expressed as mean ± SD.
Results  The MAC of Sevo was 2.30 ± 0.19%. The LCRI reduced MAC by 15% to 1.95 ± 0.23% and HCRI by 37% to 1.45 ± 0.21%. Diastolic and mean pressure increased with HCRI. Lidocaine plasma concentration was 0.84 ± 0.18 for LCRI and 1.89 ± 0.37 μg mL⁻¹ for HCRI. Seventy-five percent of HCRI dogs vomited during recovery.
Conclusion and clinical relevance  Lidocaine infusions dose dependently decreased the MAC of Sevo, did not induce clinically significant changes in HR or arterial blood pressure, but vomiting was common during recovery in HCRI.     

Platelet-Rich Plasma in the Treatment of Induced Tendinopathy in Horses: Histologic Evaluation

This study was carried out to evaluate the effect of platelet-rich plasma (PRP) on the treatment of tendinopathy induced in the superficial digital flexor tendon (TFDS) of horses, by using histologic evaluation. Six healthy crossbred geldings aged 8 to 15 years (12 ± 3) were used. The TFDS tendinopathy was provoked in both forelimbs, by intratendinous administration of 2.5 mg collagenase (2.5 mg/mL), and this procedure was considered as the beginning of the experimental phase. At 12 days after induction of the tendinopathy, the animals were subjected to the following treatments: (1) in the lesion caused in the right superficial digital flexor tendon (PRP-treated group), 2.5 mL PRP activated with calcium chloride at 0.0125 mol/L at concentrations from 320,000 to 500,000 platelets/μL, were injected; (2) in the tendinopathy of the left SDFT (control group), 2.5 mL 0.9% saline solution was administrated. Thirty-six days after the treatments, a biopsy of the injured area was performed for histologic evaluation. In both groups, the histologic analysis showed an increase in the fibroblastic density, as well as the presence of neovascularization, lymphocytes, and plasmocytes infiltrate and tissue organization at variable intensity. In the PRP-treated group, the SDFT was more organized, with the collagen fibers and fibroblasts being better arranged on the tendon matrix. The numbers of the fibroblasts and blood vessels did not differ between the groups. Histologic evaluation 36 days after tendinopathy showed that injuries under a single PRP treatment present a more uniform and organized tissue repair when compared with the control group.     

CONTRAST PARANASAL SINUSOGRAPHY FOR EVALUATION OF DISEASE OF THE PARANASAL SINUSES OF FIVE HORSES

Positive-contrast paranasal sinusography was employed to evaluate 5 horses with disease of the paranasal sinuses. Diseases of the paranasal sinuses of these horses were progressive ethmoidal hematoma, bacterial sinusitis secondary to dental disease, and neoplasia. Positive-contrast sinusography allowed more complete evaluation of disease of the paranasal sinus of the horse than did survey radiographs.     

Ultrasonographic and Endocrine Characterization of Follicular Waves in Llamas with a Special Reference to the Overlapping Phenomenon During Successive Waves

Ovarian follicular growth in non‐mated llamas occurs in successive waves that generally superimpose their origin on the regression of the preceding wave (overlapping), originating prolonged sexual receptivity in the species. The aim of this study was to perform an ultrasonographic and endocrine characterization of individual and successive waves in non‐mated llamas with a special interest on the overlapping phenomenon. Twelve llamas were examined daily by transrectal ultrasonography for at least two consecutive waves. In six females, blood samples were collected daily at the end of each examination. The development of the largest follicle (F) showed a wavelike pattern with a mean duration of 25 days. All waves evaluated were partially overlapped on the preceding wave and emerged at a mean interval of 15.8 ± 0.5 days. This interwave interval determines a mean overlapping degree of 32% of the wave length. Similarly, mean plasma oestradiol‐17β (E₂) concentrations followed a wavelike pattern. However, E₂ concentrations started to decline before the structural regression of the F was observed. Mean basal E₂ concentrations remain higher than 10.9 ± 0.6 pmol/l. In conclusion, follicular activity in non‐mated llamas is characterized by continuous emergence of successive waves that always overlap the preceding wave with variable degrees. E₂ production during the follicular wave is shorter in duration than the morphological development of the F. Finally, the overlapping phenomenon maintains increased plasma E₂ concentrations persistently and this could explain the prolonged periods of sexual receptivity registered in llamas.     

Heavy metals in horse blood, serum, and feed in Minas Gerais, Brazil

Pollution is a subject of worldwide concern and discussion and various areas of science are seeking to integrate their knowledge in an attempt to improve understanding of the harmful effects of modern human activities. Thus, the objective of the current study was to assess the potential for using the horse as a bio-indicator of environmental pollution. Blood and serum samples from 120 horses from locations with different degrees of urbanization and industrialization and the feeds used for these animals were analyzed to determine their heavy metal (Cd, Pb, Ni, Cu, and Zn) content. The data obtained were compared. The results did not show increases in heavy metal concentration in the blood and serum of the horses with the intensification of urbanization and industrialization around the farms. Only Cd, as determined in the blood of the animals, showed a certain potential for using horses as bio-indicators of environmental pollution. The data for sex, age, and chemical composition of the foodstuffs supplied to the animals were not determinants in explaining the variation in the concentrations of heavy metals observed.     

Determination of sulfonylurea herbicides in water and food samples using sol-gel glass-based immunoaffinity extraction and liquid chromatography-ultraviolet/diode array detection or liquid chromatography-tandem mass spectrometry

Immunoaffinity supports (IAS) were prepared using broad specific polyclonal anti-sulfonylurea (SU) antibodies immobilized in sol-gel glass. Two different kinds of supports were applied, crushed sol-gel monoliths and sol-gel-coated highly porous silica particles. Both were used for the quantitative enrichment of SUs in natural water and food samples followed by high-performance liquid chromatography-ultraviolet/diode array detection (HPLC-UV/DAD) and tandem mass spectrometry (LC-MS/MS), respectively. Loading, washing, and elution conditions of IAS were optimized. The capacity of supports was determined for 30 SUs and compared with the cross-reactivity pattern of the direct competitive enzyme-linked immunosorbent assay. The capacities correlated well with the affinity to individual SU compounds. Even analytes to which the polyclonal antibodies showed only a lower cross-reactivity could be enriched to a certain degree, if a sufficient capacity of IAS was provided. The IAS could be reused at least 10 times without a loss of effectiveness. Recovery of 16 selected SUs extracted from spiked water and food samples was dependent on the affinity of both immobilized antibodies to single compounds and matrix interferences. In water, 13 SUs showed recoveries higher than 80% when immunoaffinity extraction was used in combination with LC-UV/DAD. On the basis of the enrichment of 200 mL of aqueous sample, corresponding limit of detection (LOD) values ranged between 20 and 100 ng/L. The recoveries of 10 SUs, which were extracted from 10 g of potato spiked at a 10 microg/kg level, were higher than 75%. For grain samples, recoveries were at the same order for at least five SU herbicides. The LOD of LC-MS/MS measurements was about 1 order of magnitude higher, i.e., gave LODs between 1.1 and 6.9 microg/kg of food sample, depending on the compound and extraction procedure. These LODs provide evidence that the main advantage of the prepared IAS is their high selectivity for group specific recognition of SUs as compared to other nonspecific solid phase extraction materials.