人绒毛膜促性腺激素对母驴促排卵效果的研究

[目的]研究人绒毛膜促性腺激素（human chorionic gonadotropin,hCG）对母驴卵泡发育、排卵率、受胎率以及血清生殖激素水平的影响。[方法]选择优势卵泡直径在30~35 mm以及大于35 mm的母驴各30头,不同优势卵泡直径的母驴群体分别设置1个500 IU/头hCG处理组（n=10）、1个1 000 IU/头hCG处理组（n=10）、1个不接受hCG处理的对照组（n=10）。采用肌肉注射方法对各组母驴进行hCG处理。每隔24 h进行1次B超检查,观察各组母驴卵泡发育情况,测量卵泡直径;记录各组发生排卵的母驴数量,计算排卵率。对各组母驴进行人工输精,输精后第18天进行孕检,记录各组受胎母驴头数,计算各组受胎率。于hCG处理后0、24、48、72 h分别测定各组母驴血清中雌二醇（estradiol,E₂）和孕酮（progesterone,PROG）水平。[结果]2个群体母驴的卵泡直径随hCG注射剂量的增加而增大;优势卵泡直径大于35 mm的母驴群体中,肌肉注射hCG的2个组在处理后24 h内均出现排卵,而对照组母驴没有排卵;优势卵泡直径不同的2个母驴群体,在hCG处理48 h后排卵母驴数和排卵率与对照组相比均有所提高,其中,hCG处理后72 h,优势卵泡直径大于35 mm的母驴群体中,1 000 IU/头 hCG处理组的排卵率达到100%。2个母驴群体中,接受hCG处理的母驴,受胎率均高于对照,并且随hCG剂量的增加,受胎率有所提高;优势卵泡直径大于35 mm的母驴群体中,1 000 IU/头 hCG处理组的受胎率达到50%。2个母驴群体中,1 000 IU/头处理组在hCG处理后24 h的血清E₂浓度均较0 h时有较大幅度的提升,在0~72 h内血清PROG浓度的总体提升幅度较大。[结论]hCG处理可提高母驴的排卵率、受胎率以及血清中E₂和PROG水平,1 000 IU/头剂量的效果更好。     

Comparison of Efficacy of Two Dose Rates of Histrelin to Human Chorionic Gonadotropin for Inducing Ovulation in Broodmares

Between February 15 and May 17, 2011, a total of 88 broodmares (10 maiden, 10 barren, and 68 foaling) maintained on pasture in southeast Texas were examined three times weekly (Tuesday, Thursday, Saturday) by transrectal palpation and ultrasonography. On Tuesday or Thursday, mares in estrus with uterine edema, a relaxed cervix, and a dominant follicle ≥34 mm in diameter were alternately assigned to treatment with the following: group (1) 2,500-unit human chorionic gonadotropin (hCG), intravenous; group (2) 1.0-mg BioRelease Histrelin (Biorelease Technologies, Lexington, KY), intramuscular; or group (3) 0.5-mg BioRelease Histrelin, intramuscular. Ovulation was confirmed by ultrasonographic examination. The percentage of mares ovulating within 2 days appeared to be similar between maiden, barren, and foaling mares, so responses for all mares were totaled for analysis. A nonsignificant trend for higher ovulation rates within 2 days was noted for both dose rates of histrelin compared with hCG treatment (31/37, 84%; 34/37, 92%; and 33/36, 92% for groups 1-3, respectively) (P = .45). Ovulatory responses appeared to improve for both products as the season progressed, yet no differences were detected between response rates to histrelin or hCG for any month (P ≥ .50). The use of 1.0- or 0.5-mg BioRelease Histrelin was found to be at least equally effective as hCG treatment for inducing ovulation within 2 days of treatment throughout the breeding season.     

Efficacy of Low‐ and High‐Dose Trilostane Treatment in Dogs (< 5 kg) with Pituitary‐Dependent Hyperadrenocorticism

Background

Trilostane is commonly used to treat pituitary‐dependent hyperadrenocorticism (PDH) in dogs. There are differing opinions regarding the dose and frequency of trilostane administration in dogs with PDH.

Objectives

To compare the efficacy of 2 trilostane protocols in the treatment of dogs with PDH.

Animals

Sixteen client‐owned dogs with PDH and a body weight <5 kg.

Methods

Prospective observational study. Group A (n=9; low‐dose treatment group) received 0.78 ± 0.26 mg of trilostane/kg PO every 12 h and group B (n = 7; high‐dose treatment group) 30 mg of trilostane/dog PO every 24 h. All of the dogs were reassessed at 2, 4, 8, 12, 16, and 24 weeks after the initiation of treatment.

Results

An improvement in both ACTH‐stimulated serum cortisol concentrations and clinical signs occurred more slowly in group A than in group B; however, after 20 weeks of treatment, 2/7 dog in group B had clinical signs and abnormal laboratory findings consistent with hypoadrenocorticism. At 24 weeks, an improvement in the clinical findings of all of the dogs in both groups was detected.

Conclusions and clinical importance

In dogs with PDH, twice‐daily administration of low‐dose trilostane is an effective approach to the management of PDH. In addition, our results suggest fewer potential adverse effects if trilostane is administered twice daily in the lower dose.     

Cyclooxygenase Expression and Platelet Function in Healthy Dogs Receiving Low‐Dose Aspirin

Background

Low‐dose aspirin is used to prevent thromboembolic complications in dogs, but some animals are nonresponsive to the antiplatelet effects of aspirin (“aspirin resistance”).

Hypothesis/Objectives

That low‐dose aspirin would inhibit platelet function, decrease thromboxane synthesis, and alter platelet cyclooxygenase (COX) expression.

Animals

Twenty‐four healthy dogs.

Methods

A repeated measures study. Platelet function (PFA‐100 closure time, collagen/epinephrine), platelet COX‐1 and COX‐2 expression, and urine 11‐dehydro‐thromboxane B₂ (11‐dTXB₂) were evaluated before and during aspirin administration (1 mg/kg Q24 hours PO, 10 days). Based on prolongation of closure times after aspirin administration, dogs were divided into categories according to aspirin responsiveness: responders, nonresponders, and inconsistent responders.

Results

Low‐dose aspirin increased closure times significantly (62% by Day 10, P < .001), with an equal distribution among aspirin responsiveness categories, 8 dogs per group. Platelet COX‐1 mean fluorescent intensity (MFI) increased significantly during treatment, 13% on Day 3 (range, ?29.7–136.1%) (P = .047) and 72% on Day 10 (range, ?0.37–210%) (P < .001). Platelet COX‐2 MFI increased significantly by 34% (range, ?29.2–270%) on Day 3 (P = .003) and 74% (range, ?19.7–226%) on Day 10 (P < .001). Urinary 11‐dTXB₂ concentrations significantly (P = .005, P < .001) decreased at both time points. There was no difference between aspirin responsiveness and either platelet COX expression or thromboxane production.

Conclusions and Clinical Importance

Low‐dose aspirin consistently inhibits platelet function in approximately one‐third of healthy dogs, despite decreased thromboxane synthesis and increased platelet COX expression in most dogs. COX isoform expression before treatment did not predict aspirin resistance.

     

Equine Chorionic Gonadotropin and Human Chorionic Gonadotropin Stimulation Increase the Number of Luteinized Follicles and the Progesterone Level Compared with Cabergoline Stimulation in Anoestrus Bitches

In this study, ovarian morphologies and blood progesterone concentrations following oestrous induction in bitches were examined. Fifty‐three clinically healthy anoestrus bitches received cabergoline at a daily dose of 5 μg/kg of body weight per os for 21 days (group I) or subcutaneous equine chorionic gonadotropin at a dose of 20 IU/kg of body weight for five consecutive days with an additional 500 IU s.c. per bitch of human chorionic gonadotropin on the last day of treatment (group II). Twenty bitches that spontaneously displayed oestrous signs were left untreated and served as controls (group III). The induced oestrous rates and ovulation rates in groups I and II were 60.0% vs 64.3% and 86.7% vs 83.3%, respectively. Morphological assessments of the ovarian structures after ovariohysterectomy revealed an increase in the number of luteinized follicles and cysts in group II compared with the two other groups (p < 0.001). In contrast, the numbers of corpora lutea and follicles were similar in all groups. In accordance with the above‐mentioned alteration, the progesterone concentration in the gonadotropin group (II) was increased (p < 0.001) in the periovulatory period compared with the other two groups. During the entire sampling period, the progesterone profiles in the cabergoline (I) and control (III) groups were similar and typical of normally cycling bitches. In conclusion, gonadotropin treatment is associated with an increased progesterone level during the periovulatory period that probably originates from luteinized follicles, whereas cabergoline treatment induces cycles with both physiological progesterone concentrations and ovarian morphologies.     

Esophageal Dysfunction in Dogs with Idiopathic Laryngeal Paralysis: A Controlled Cohort Study

Objectives— To compare esophageal function in dogs with idiopathic laryngeal paralysis (ILP) to age and breed matched controls; to determine if dysfunction is associated with aspiration pneumonia over 1 year; and to compare clinical neurologic examination of dogs with ILP at enrollment and at 1 year. Study Design— Prospective controlled cohort study. Animals— Dogs with ILP (n=32) and 34 age and breed matched healthy dogs. Methods— Mean esophageal score was determined for each phase of 3 phase esophagrams, analyzed blindly. After unilateral cricoarytenoid laryngoplasty, dogs with ILP were reexamined (including thoracic radiography) at 1, 3, 6, and 12 months. Neurologic status was recorded at enrollment, 6 and 12 months. Results— Esophagram scores in dogs with ILP were significantly higher in each phase compared with controls, most notably with liquid (P<.0001). Dysfunction was more pronounced in the cervical and cranial thoracic esophagus. Five dogs that had aspiration pneumonia during the study had significantly higher esophagram scores than dogs that did not develop aspiration pneumonia (P<.02). Ten (31%) ILP dogs had generalized neurologic signs on enrollment and all ILP dogs developed neurologic signs by 1 year (P<.0001). Conclusions— Dogs with ILP also have esophageal dysfunction. Postoperative aspiration pneumonia is more likely in dogs with higher esophagram scores. Dogs with ILP will most likely develop generalized neuropathy over the course of 1 year. Clinical Relevance— Esophagrams and neurologic examinations should be performed on all dogs with ILP.     

Efficacy of Omeprazole versus High‐Dose Famotidine for Prevention of Exercise‐Induced Gastritis in Racing Alaskan Sled Dogs

Background: Omeprazole and famotidine both reduce severity of exercise‐induced gastritis, but administering famotidine is easier than administering omeprazole during racing competition. Hypothesis: Famotidine is more efficacious than no treatment in reducing severity of exercise‐induced gastritis; and high‐dose famotidine is more efficacious than omeprazole in reducing severity of exercise‐induced gastritis. Animals: Experiment 1: Randomized placebo‐controlled study, 36 sled dogs (3–8 years); Experiment 2: Randomized positive‐control study, 52 sled dogs (2–8 years). Methods: Experiment 1: Equal numbers of dogs randomly assigned to famotidine (20 mg q24h) or no treatment groups. Gastroscopy was performed 24 hours after the dogs ran 330 miles. Mucosal appearance was blindly scored by previously described scoring system. Experiment 2: Equal numbers of dogs randomly assigned to omeprazole (20 mg q24h) or high‐dose famotidine (40 mg q12h) groups. Gastroscopy was performed 48 hours before and 24 hours after the dogs ran 300 miles. Mucosal appearance was blindly scored by previously described scoring system. Results: Famotidine reduced the prevalence of clinically relevant, exercise‐induced gastric lesions compared with no treatment (7/16 versus 11/16, P= .031). Compared with high‐dose famotidine, omeprazole significantly decreased the severity (0.4 versus 1.2, P= .0002) and prevalence (2/23 versus 7/21, P= .049) of gastric lesions. Conclusions and Clinical Relevance: Although famotidine provides some benefit in the prevention of exercise‐induced gastric lesions, omeprazole is superior to famotidine in preventing gastritis in dogs running 300 miles. Routine administration of omeprazole is recommended to prevent stress‐associated gastric disease in exercising and racing Alaskan sled dogs.     

Pharmacokinetics of Single‐Dose Rectal Zonisamide Administration in Normal Dogs

Background

Few medications are available for parental administration to animals with seizures. Rectal administration of medications is often used if the animal cannot be administered oral medications.

Hypothesis/Objectives

To determine the pharmacokinetic differences in zonisamide when administered rectally in either of 2 vehicles and PO to dogs.

Animals

Eight healthy research dogs.

Methods

Randomized cross‐over design. Zonisamide, 10 mg/kg, was administered rectally in polyethylene glycol (PEG‐R), rectally in water (H₂O‐R), and as an oral capsule. Plasma zonisamide concentrations were measured until 72 hours after administration. Zonisamide was quantitated by HPLC and plasma concentration versus time curve data was analyzed by using noncompartmental modeling.

Results

Mean maximum plasma zonisamide concentrations (μg/mL) were significantly higher after oral administration (11.56 ± 4.04) compared to H₂O‐R (5.00 ± 1.83) (P = .004). Disappearance half‐life (hours) and mean time to maximum concentration (hours) were not significantly different between methods of administration. Mean relative bioavailability of PEG‐R (85 ± 69%) was significantly higher than that of H₂O‐R (53 ± 37%) (P = .039). Dogs tolerated all dosing forms with no evidence of adverse effects.

Conclusions and Clinical Importance

The vehicle in which zonisamide is dissolved influences rectal bioavailability, with PEG preferred to H₂O‐R. Because of the prolonged time to maximum concentration, rectal administration of zonisamide should not be used to treat status epilepticus in dogs. A dose higher than what was used in this study might be necessary, if currently recommended minimum therapeutic concentrations (10 μg/mL) are to be achieved with a single‐dose administration.     

Phase I Dose Escalation of Single‐Agent Vinblastine in Dogs

Background: Vinblastine (VBL) is commonly used in dogs at a dosage of 2.0 mg/m². The minimal toxicity observed at this dosage indicates that higher dosages might be well tolerated. Hypothesis: The maximum tolerated dosage (MTD) for a single VBL treatment is higher than the previously published dosage of 2.0 mg/m². Animals: Twenty‐three dogs with lymphoma or cutaneous mast cell tumors. Methods: Dogs received 1 single‐agent VBL treatment IV. The starting dosage was 3.0 mg/m², and dosages were increased in increments of 0.5 mg/m² in cohorts of 3 dogs. Hematologic toxicity was assessed with weekly CBCs. Gastrointestinal toxicity was assessed from medical histories from owners. Once the MTD was determined, additional dogs were treated with VBL at that dosage. Dogs whose cancers responded to VBL continued to receive treatments q2–3 weeks. Results: VBL dosages ranged from 3.0 to 4.0 mg/m². Neutropenia was the dose‐limiting toxicity, with the nadir identified 7 days after treatment and resolving by 14 days after treatment. The MTD was 3.5 mg/m². Sixteen dogs were treated at this dosage, and 3 experienced severe toxicity characterized by asymptomatic grade 4 neutropenia, febrile grade 4 neutropenia, and death. Gastrointestinal toxicity was mild and self‐limiting. Preliminary evidence of antitumor activity was identified in 2 of 12 dogs with lymphoma treated at the MTD. Conclusions and Clinical Importance: In dogs, single‐agent VBL is well tolerated at a dosage of 3.5 mg/m² IV. At this dosage, the minimum safe treatment interval is q2 weeks, and adjunct treatment with prophylactic antibiotics should be considered.     

Effects of Prolonged Exposure to Low‐Dose Fumonisin B1 in Pigs

From the point of view of human exposure, fumonisins (FB₁, FB₂, FB₃, FB₄), a relatively recently (1988) discovered and identified group of mycotoxins, represent one of the five most important mycotoxin groups causing human disease. In an earlier experiment studying the effects of relatively low doses (10, 20 and 40 p.p.m.) of FB₁ in weaned piglets, it was established that the 4‐week feeding of 10 p.p.m. (mg/kg feed) FB₁ produced mild pulmonary oedema. This suggested the importance of studies with even lower doses of the toxin to determine the tolerable limits. The objective of this experiment was therefore to study the effects of prolonged (8‐week) exposure to still lower concentrations (0, 1, 5 and 10 mg/kg feed) of FB₁. The 8‐week feeding of FB₁ in low concentrations (1–10 p.p.m.) did not cause clinical signs and significant performance impairment in pigs, but rendered irreversible the chronic changes that had already developed in the animals in a dose‐dependent manner. Dissection revealed pathological alterations of the lungs in one of the animals given 1 p.p.m. (n=4), in two animals exposed to 5 p.p.m. (n=5), and in three animals given 10 p.p.m. (n=4). In all three treatment groups, proliferation of the connective tissue fibres, primarily of those around the lymphatic vessels, in the subpleural and interlobular connective tissue of the lungs, extending to the peribronchial and peribronchiolar areas, was seen. The results of this experiment call attention to the risk of prolonged low‐dose toxin exposure, which has very important public health implications.     

Use of Equine Chorionic Gonadotropin to Control Reproduction of the Dairy Cow: A Review

Equine chorionic gonadotropin (eCG) is a member of the glycoprotein family of hormones along with LH, FSH and thyroid‐stimulating hormone. In non‐equid species, eCG shows high LH‐ and FSH‐like activities and has a high affinity for both FSH and LH receptors in the ovaries. On the granulosa and thecal cells of the follicle, eCG has long‐lasting LH‐ and FSH‐like effects that stimulate oestradiol and progesterone secretion. Thus, eCG administration in dairy cattle results in fewer atretic follicles, the recruitment of more small follicles showing an elevated growth rate, the sustained growth of medium and large follicles and improved development of the dominant and pre‐ovulatory follicle. In consequence, the quality of the ensuing CL is improved, and thereby progesterone secretion increased. Based on these characteristics, eCG treatment is utilized in veterinary medicine to control the reproductive activity of the cow by i) improving reproductive performance during early post‐partum stages; ii) increasing ovulation and pregnancy rates in non‐cyclic cows; iii) improving the conception rate in cows showing delayed ovulation; and finally, iv) eCG is currently included in protocols for fixed‐time artificial insemination since after inducing the synchrony of ovulation using a progesterone‐releasing device, eCG has beneficial effects on embryo development and survival. The above effects are not always observed in cyclic animals, but they are evident in animals in which LH secretion and ovarian activity are reduced or compromised, for instance, during the early post‐partum period, under seasonal heat stress, in anoestrus animals or in animals with a low body condition score.     

人绒毛膜促性腺激素(HCG)对杂交黄牛、水牛受胎率的影响

近年来,广西象州县的多个牛人工授精品改点的受胎率,黄牛为33%～51%,水牛为35%～55%,母牛的受胎率仍有较大的提升空间。该试验利用HCG能够促进母牛卵泡发育和排卵这一特性,在母牛发情时肌肉注射HCG后进行输精,并观察其对母牛受胎率的影响,以及是否能够提高牛人工授精的效果。试验结果表明,使用HCG能够明显提高牛人工授精的受胎率,同时也提高了工作效率。     

Effect of Weaning to Oestrus Interval and Equine Chorionic Gonadotropin on Vaginal Electrical Impedance During Peri‐oestrus in Sows

The influence of weaning to oestrus interval, its interaction with parity and equine chorionic gonadotropin (eCG) on changes of vaginal impedance in sows after weaning was examined. The impedance measurements were carried out by a four‐terminal method. Sows were monitored for oestrus via exposure to a sexually mature boar. The interval from weaning to oestrus was longer in primiparous than multiparous sows (p < 0.01). A significant negative correlation was found between the interval from weaning to oestrus and parity. Repeated measures analysis showed that the interval from weaning to oestrus and parity and their interactions had a significant effect on the vaginal impedance in peri‐oestrus. The vaginal impedance during pro‐oestrus gradually decreased in all groups of sows with the weaning to oestrus interval from 4 to 8 days (p < 0.05). In the subsequent period, the vaginal impedance increased and was significantly lower from 1 to 3 days after oestrus onset in sows with the weaning to oestrus interval 7–8 days than 4–6 days. Similarly, the vaginal impedance during pro‐oestrus gradually decreased in all groups of sows with parity 1–5 (p < 0.01). In the next period, the vaginal impedance increased and was significantly lower from 2–3 days after oestrus onset in sows of parity 1 than parity 2–5. Repeated measures analysis showed that eCG treatment had a significant effect on the vaginal impedance in peri‐oestrus. Sows treated with eCG displayed the decrease and increase of vaginal impedance due to oestrus onset earlier than untreated sows. The results indicate that the weaning to oestrus interval, its interaction with parity and eCG markedly affect the vaginal impedance in sows during peri‐oestrus.     

Efficacy and Toxicity of Doxorubicin/Cyclophosphamide Maintenance Therapy in Dogs with Multicentric Lymphosarcoma

Doxorubicin/cyclophosphamide were evaluated as maintenance drugs for dogs with multicentric lymphosarcoma (n = 28). Median remission time of all dogs was 173 days. Remission duration was shorter, however, in dogs with stage IV/V disease, in dogs with pretreatment hypoalbuminemia, and in dogs that had received glucocorticoids before initiation of chemotherapy (P less than 0.04). Nineteen dogs were evaluable for toxicity. Dose-limiting gastrointestinal toxicosis was observed in three dogs, neutropenia was observed in three dogs, and cardiomyopathy was observed in three dogs. The doxorubicin/cyclophosphamide protocol described in this report is safe and effective in treating canine multicentric lymphosarcoma. Clinical stage, pretreatment steroid therapy, and hypoalbuminemia are prognostic factors for response to this protocol.