Characterization of Cq3, a quantitative trait locus that controls plasma cholesterol and phospholipid levels in mice

Cq3 was identified in C57BL/6J (B6) x KK-Ay F2 mice as a quantitative trait locus (QTL) that controls plasma cholesterol and phospholipid levels, and normolipidemic B6 allele was associated with increased lipids. Cq3 was statistically significant in F2-a/a, but not in F2-Ay/a; probably because the Cq3 effect was obscured by introduction of the Ay allele, which in itself has a strong hyperlipidemic effect. Because the peak LOD score for Cq3 was identified near D3Mit102 (49.7 cM) on chromosome 3, linkage analyses with microsatellite markers located at 49.7 cM were performed in KK x RR F2, B6 x RR F2, and KK x CF1 F2. However, even a suggestive QTL was not identified in any of the three F2. By testing all pairs of marker loci, I found a significant interaction between Cq3 and the Apoa2 locus, and F2 mice with the Apoa2(KK)/Apoa2(KK); D3Mit102(B6)/D3Mit102(B6) genotype had significantly higher cholesterol levels than did F2 mice with other genotypes. The results showed that the ;round-robin' strategy was not always applicable to the search for QTL genes; probably because specific gene-to-gene interaction limited the validity of the strategy to the utmost extent.     

Quantitative trait locus analysis of plasma cholesterol levels and body weight by controlling the effects of the Apoa2 allele in mice

Colleagues and I previously performed quantitative trait locus (QTL) analysis on plasma total-cholesterol (T-CHO) levels in C57BL/6J (B6) x RR F2 mice. We identified only one significant QTL (Cq6) on chromosome 1 in a region containing the Apoa2 gene locus, a convincing candidate gene for Cq6. Because Cq6 was a highly significant QTL, we considered that the detection of other potential QTLs might be hindered. In the present study, QTL analysis was performed in B6.KK-Apoa2b N(8) x RR F2 mice [B6.KK-Apoa2b N(8) is a partial congenic strain carrying the Apoa2b allele from the KK strain, and RR also has the Apoa2b allele] by controlling of the effects of the Apoa2 allele, for identifying additional QTLs. Although no significant QTLs were identified, 2 suggestive QTLs were found on chromosomes 2 and 3 in place of the effects of the Apoa2 allele. A significant body weight QTL was identified on chromosome 3 (Bwq7, peak LOD score 5.2); its effect on body weight was not significant in previously analyzed B6 x RR F2 mice. Suggestive body weight QTL that had been identified in B6 x RR F2 mice on chromosome 4 (LOD score 3.8) was not identified in B6.KK-Apoa2b N(8) x RR F2 mice. Thus, contrary to expectation, the genetic control of body weight was also altered significantly by controlling of the effects of the Apoa2 allele. The QTL mapping strategy by controlling of the effects of a major QTL facilitated the identification of additional QTLs.     

Productivity effects of bovine mange and control with ivermectin

A randomised block design study was conducted to evaluate the effects of mange on cattle. Twenty-four Simmentaler Fleckvieh bulls were formed into eight replicates of three bulls based on Day -56 body weight (288-414 kg). Within replicates bulls were randomly allocated to groups G1: uninfested control, G2: infested control or G3: infested, treated with 0.2mg ivermectin/kg (1% ivermectin injection; IVOMEC, Merial) on Day 0. The G2 and G3 bulls were infested with Sarcoptes/Chorioptes mites on Days -56 and -49. Feed consumption was recorded daily throughout the study (Days -56 to 56). Body weights were measured and serum samples collected. Mites were counted at bi-weekly intervals from Day -14 on. The carcasses of the bulls and the leather produced from their hides were evaluated. Differences between variables were declared significant if P相似文献   

Effects of psoroptes ovis infection and its control with an ivermectin controlled-release capsule on growing sheep. 1. Evaluation of weight gain, feed consumption and carcass value

To evaluate the prophylactic and therapeutic effects of an ivermectin controlled-release capsule (IVM-CRC) on the productivity of growing sheep infested with Psoroptes ovis 24 male and 24 female Merino landrace lambs, 5-6 months old and weighing 21.2-35.0 kg, were used. Sixteen replicates of three animals were formed based on sex and Day 0 body weight. Within each replicate animals were randomly allocated to one of three groups: untreated control; IVM-CRC on Day 0; IVM-CRC on Day 84. For treatment an IVM-CRC for sheep weighing 20-45 kg was used which is designed to deliver ivermectin at a minimum dose of 20 microg/kg per day for 100 days. The lambs were infested with 50-60 P. ovis mites each on Days 14 and 21. Mites in skin scrapings were counted on Days 70, 84, 98, 112 and 126. Body weight and feed consumption were measured every 2 weeks from Day 0 to 126. The animals were slaughtered on Day 127 and their carcasses evaluated. The IVM-CRC treatment on Day 0 prevented the establishment of P. ovis. All untreated lambs became infested. The lambs treated with an IVM-CRC on Day 84 became mite-free from Day 112 onwards. The lambs treated on Day 0 had significantly (p<0.05) greater body weight gain from Day 0 to 84 (13.9 kg) and Day 0 to 126 (20.9 kg) than the untreated controls (9.6 and 12.8 kg, respectively) and the sheep treated on Day 84 (8.4 and 14.9 kg, respectively). Feed consumption (Days 0-126) for sheep treated with the IVM-CRC on Day 0 was higher than for sheep treated on Day 84 (p<0.05) and for the untreated controls (p<0.1). The carcasses of sheep treated with the IVM-CRC on Day 0 had significantly (p<0.05) higher warm and cold weights, carcass yield, rib eye area and back fat thickness than the untreated control group and the sheep treated with the IVM-CRC on Day 84. The sheep treated with the ivermectin CRC on either Day 0 or 84 had significantly (p<0.05) better muscle scores and lower muscle pH 1h post-slaughter than the untreated controls. There was no significant (p>0.1) difference between warm and cold carcass weights, carcass yield and rib eye area between sheep treated on Day 84 and untreated controls.     

SPF级BALB/cC57BL/6小鼠繁殖性能及生长发育的比较研究

为提高SPF级实验动物的质量,选择10周龄BALB/c C57BL/6小鼠各50只（雌雄各半）,采取雌雄1？1近亲交配繁殖,并统计其生长发育和繁殖性能指标。BALB/c小鼠1～3周龄的平均窝重及离乳后的体重增长明显大于C57BL/6小鼠（p〈0.01）。第1胎交配分娩间隔,第1和第3胎离乳育成率品系间差异均有显著性（P〈0.05及P〈0.01）。BALB/c小鼠的体格比C57BL/6小鼠大,带乳能力比C57BL/6小鼠强但产仔能力比C57BL/6小鼠弱。     

A2a基因敲除小鼠生物学特性的初步研究

为了解A2a基因敲除小鼠的生物学物性,给研究心血管疾病及神经疾病提供部分基础资料,试验采用全自动生化分析仪及血细胞分析仪分别对60日龄C57BL/6、A2a雌雄小鼠的常用血液学指标及生化指标值进行检测,并测定了各小鼠的脏器。结果:C57BL/6和A2a小鼠血液的血小板计数、红细胞分布宽度差异显著(P0.05)。C57BL/6和A2a小鼠的丙氨酸转氨酶、肌酸激酶差异显著(P0.05),乳酸脱氢酶差异极显著(P0.01),脏器系数无显著差异(P0.05)。     

Quantitative trait loci that control body weight and obesity in an F2 intercross between C57BL/6J and DDD.Cg-Ay mice

I have developed a congenic mouse strain for the A(y) allele at the agouti locus in an inbred DDD/Sgn strain, DDD.Cg-A(y). DDD.Cg-A(y) females are extremely obese and significantly heavier than B6.Cg-A(y) females. The objectives of this study were to determine the genetic basis of obesity in DDD.Cg-A(y) mice, and to determine whether or not their high body weight was due to the presence of DDD background-specific modifiers. I performed quantitative trait locus (QTL) analyses for body weight and body mass index in two types of F(2) mice [F2 A(y) (F(2) mice carrying the A(y) allele) and F(2) non-A(y) (F2 mice without the A(y) allele)] produced by crossing C57BL/6J females and DDD.Cg-A(y) males. The results of the QTL analysis of F(2) A(y) mice were very similar to those obtained for F(2) non-A(y) mice. It was unlikely that the high body weight of DDD.Cg-A(y) mice was due to the presence of specific modifiers. When both F(2) datasets were merged and analyzed, four significant body weight QTLs were identified on chromosomes 6, 9, and 17 (2 loci) and four significant obesity QTLs were identified on chromosomes 1, 6, 9, and 17. Although the presence of DDD background-specific modifiers was not confirmed, a multifactorial basis of obesity in DDD.Cg-A(y) females was thus revealed.     

Field efficacy of injectable and pour-on moxidectin in cattle naturally infested with Psoroptes ovis (Acarina: Psoroptidae).

Field efficacy of moxidectin, a macrocyclic lactone endectocide, was evaluated in cattle naturally infested with Psoroptes ovis. Three groups of six animals were used based on parasitological and clinical status. Group 1 animals received one subcutaneous injection of injectable moxidectin at 0.2 mg kg-1 body weight; Group 2 animals received topically one dose of 0.5 mg kg-1 body weight of pour-on moxidectin; Group 3 individuals remained untreated as controls. Efficacy was assessed by (a) taking skin samples from each animal on Days -4, 14, 28, 42 and 56 post-treatment (PT) and observing numbers of viable mite stages and species and (b) clinical examination of animals on Days 14, 28, 42 and 56 with the percentage of affected body surface calculated for each animal on Days -4, 28 and 56. Both formulations gave 100% efficacy as no live mites were found in Groups 1 or 2, 14, 28 and 56 days after treatment. Clinical indices showed a sharp decrease in the affected body surface area from a mean of 5.48% and 6.1% on Day -4 in Groups 1 and 2, respectively, to 0% in both groups on Days 28 and 56 PT. All untreated animals remained positive until Day 28. The clinical condition of the controls worsened rapidly during the experiment (mean clinical index: 2.87% and 13.05% on Days -4 and 28, respectively) and they were given an emergency treatment on Day 28. No side-effects were observed with either formulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Parasites as stressors: plasma cortisol responses of goats infected with the stomach worm Haemonchus contortus to exogenous corticotropin (ACTH)

Ten male, juvenile pigmy goats of similar age and weight were allocated randomly to two groups. Goats in one group were each inoculated with 20,000 infective larvae of Haemonchus contortus. The other group served as uninfected controls. Goats were housed together, and precautions were taken to avoid the creation of differential, between group, stressogenic circumstances. Body weights, nematode egg production, hematocrits, and clinical signs were monitored over a 61-day period following inoculation of larvae. On Days 59 and 61, adrenal response tests (ART) were conducted by measuring the levels of plasma cortisol before and 2 h after administration of porcine ACTH at the rate of 0.35 I.U. kg-1 body weight on Day 59 and 2.2 I.U. kg-1 on Day 61. Although the infections did not reduce body weights, they were 'heavy' on the basis of egg production, and led to significant reductions in packed erythrocyte volumes. There was no significant difference between the groups of goats in the responses to ART, indicating that the infections did not produce sufficient stress to reduce the ability of the adrenal cortex to respond to exogenous ACTH.     

Efficacy and safety of 3 versus 5 days of meloxicam as an analgesic for feline onychectomy and sterilization

Three- or 5-day courses of meloxicam [0.2 mg/kg body weight (BW) subcutaneously pre- or postoperatively on Day 1 followed by 0.05 mg/kg BW, PO per day thereafter] were assessed for analgesic efficacy and safety in 50 client-owned cats undergoing onychectomy and sterilization. Primary outcome parameters were analgesia score, gait/lameness score, and need for rescue analgesia assessed at times 0, 1, 4, 7, 24, 28, 35, 48, 52, 57 hours and on Day 5. Packed cell volume/total solids and serum biochemistry were assessed at time 0 and Days 3 and 5. There were no differences in efficacy and safety parameters regardless of the treatment protocol employed and no cat required rescue analgesia. The patients that received meloxicam preoperatively had statistically better gait/lameness scores than those that received meloxicam postoperatively, supporting the principle of preemptive analgesia.     

A proximal genomic region of mouse chromosome 10 contains quantitative trait loci affecting fatness

Body weight and fatness are quantitative traits of agricultural and medical importance. In previous genome‐wide quantitative trait locus (QTL) analyses, two QTLs for body weight and weight gain at an early postnatal growth period were discovered on mouse chromosome 10 from a gene pool of wild subspecies mice, Mus musculus castaneus. In this study, we developed a congenic strain with an approximately 63‐Mb wild‐derived genomic region on which the two growth QTLs could be located, by recurrent backcrossing to the common inbred strain C57BL/6J. We compared body weights at 1–10 weeks of age, body weight gains at 1–3, 3–6 and 6–10 weeks, internal organ weights and body lengths between the congenic strain developed and C57BL/6J. Unfortunately, no effects of the two growth QTLs on body weights and weight gains were confirmed. However, at least two new QTLs affecting fatness traits were discovered within the introgressed congenic region. The wild‐derived allele at one QTL increased body mass index, whereas at another one it decreased white fat pad weight and adiposity index. Thus, the congenic mouse strain developed here is a useful model animal for understanding the genetic and molecular basis of fat deposition in livestock as well as humans.     

Toltrazuril and sulphonamide treatment against naturally Isospora suis infected suckling piglets: Is there an actual profit?

A study was carried out to assess the efficacy and the economic profit of prophylactic treatment against Isopsora suis with toltrazuril or with a sulfamethazine/trimethoprim combination in piglets from an intensive pig farm. Thirty-one litters were included in study. Eight litters were treated once with toltrazuril (20 mg/kg b.w.) at 3 days of age (Toltra group); 8 litters were treated with the sulphonamide combination (sodium sulfamethazine 35 mg and trimethoprim 7 mg/kg b.w.) for 3 consecutive days starting at 3 days of age (Sulfa group), and 15 litters were untreated (control group). Counts of oocyst per gram on pooled feces sampled from each litter were carried out on Days 7, 14, 21 and 28 and diarrhea was registered daily from pooled samples. Piglets were weighed on Days 1, 7 and 28 and mean weight gain (WG) and daily weight gain (DWG) were evaluated. The economic profit of treatment was evaluated comparing the WG of piglets of each treatment group from the day of birth to Day 28. On Days 14, 21 and 28, toltrazuril showed a better efficacy in controlling fecal oocyst output, diarrhea and weight gain compared with sulphamidic treatment (P < 0.001). The budgeting analysis showed a return of economic benefit of € 0.915 per toltrazuril-treated piglets and an additional cost of € 1.155 per sulphonamide-treated piglets.     

Eprinomectin pour-on for control of Boophilus microplus (Canestrini) ticks (Acari: Ixodidae) on cattle

The efficacy of a commercial pour-on formulation of eprinomectin, a macrocyclic lactone, against experimental infestations of Boophilus microplus (Canestrini) ticks was evaluated in two trials involving 27 Bos taurus calves. The first trial was designed to evaluate the effects of a single treatment at a dose of 0.5 mg/kg of body weight against standard size B. microplus females (4.5-8.0 mm long). A significant reduction in tick numbers (P<0.05, Wilcoxon test) was observed between treated calves as compared to untreated ones from Day 3 (44% efficacy) after treatment to the end of the trial on Day 28 (96.9%), with a peak efficacy of 97.1% on Day 21. In the second trial the effect of eprinomectin on standard size tick numbers, engorgement weight and fertility of female ticks from calves with a single treatment dose of 1 mg/kg on Day 0 and calves treated twice at a dose of 0.5 mg/kg on Days 0 and 4 was evaluated. An efficacy >93% was obtained from Day 2 to Day 28 after treatment in calves treated twice at 0.5 mg/kg, and to the end of the trial (Day 35) in calves treated once with 1 mg/kg. The 1mg/kg treatment provided >98% residual efficacy for at least 7 days. During the first part of the second trial the efficacy of eprinomectin resulted from a dramatic adverse effect on engorgement weight and fertility of female ticks, with 100% control on Day 5 (dosage of 1 mg/kg) and on Days 6 and 7 (two doses of 0.5 mg/kg). Following Day 7, most of the effect was due to reduction in the number of standard size female ticks.     

Evaluation of the efficacy of fipronil formulations in the treatment and control of biting lice,Trichodectes canis (De Geer, 1778) on dogs

The efficacy of FRONTLINE SPRAY (0.25% (w/v) fipronil), FRONTLINE SPOT-ON FOR DOGS (10% (w/v) fipronil) and FRONTLINE PLUS FOR DOGS (10% (w/v) fipronil and 9% (S)-methoprene) against the biting louse Trichodectes canis on dogs was confirmed under laboratory conditions. A field study evaluated the efficacy of a single topical application of FRONTLINE SPRAY and FRONTLINE SPOT-ON against the parasite on dogs. A total of 48 dogs of mixed breeds, both sexes, aged 2 months-7 years and weighing 1.8-37.0kg were used. The animals were either experimentally (laboratory study) or naturally (field study) infested with lice. Dogs were housed individually in order to prevent contact between animals. In the laboratory study, animals were allocated based on pre-treatment louse counts from 38 hair coat-partings per animal. Dogs were randomly assigned to the four treatment groups: (1) untreated control; (2) FRONTLINE SPRAY, at 6ml/kg; (3) FRONTLINE SPOT-ON as per label and (4) FRONTLINE PLUS as per label. Dogs in treatment groups 2-4 were treated twice topically on Days 0 and 28. The number of live lice in the 38 hair coat-partings per animal were counted on Days 2, 7 and weekly to Day 63. In addition, a whole body comb count was performed on Day 63. No live T. canis were found on dogs treated with FRONTLINE formulations at any post-treatment examination. The difference from controls was significant (P<0.01) for each product at each examination. Based on the whole body comb count at Day 63, the efficacy of each product was determined to be 100%. In the field study, dogs were allocated in strict order of presentation. Dogs were randomly allocated to one of the three treatment groups: (1) BOLFO collar (propoxur); (2) FRONTLINE SPRAY, at 6ml/kg and (3) FRONTLINE SPOT-ON as per label. Dogs were treated once topically on Day 0. The number of live lice was determined by whole body searches on Days 0 (pre-treatment), 2, 28 and 42. Louse counts of dogs treated with either FRONTLINE SPRAY, or FRONTLINE SPOT-ON were not different than those of dogs receiving the propoxur collar. The efficacy was determined to be >98% on Day 2 and, 100% on Days 28 and 42 in all treatment groups. The results of these studies demonstrate that fipronil in topical formulations is effective for treatment and control of biting lice (T. canis) infestations on dogs.     

The effect of a temporal change in ingestion rates of fluorine (F) in soil on the concentration of F in serum and bone of young sheep

AIM: To determine the changes in concentrations of fluorine (F) in serum and bone of young sheep given a high intake of F, as F in soil, followed by a low intake of F, to simulate the varying intakes experienced by grazing sheep. METHODS: Sixty autumn-born, weaned, mixed-sex lambs were randomly divided into two groups (n=30). One group (Control) was fed a low-F (12 mg/kg dry matter; DM) lucerne/ grain diet for 345 days, while the other group (High soil-F) was fed a high-F (224 mg/kg DM) lucerne/grain diet containing 10% soil for 94 days and then a low-F diet for a further 251 days. Blood samples were collected on Days 1, 32, 94, 108, 153, 214, 280 and 345, to determine concentrations of F in serum. Groups of five or six animals from each group were killed on Days 1, 94, 153, 214, 280 and 345, to collect radii and humeri for determination of F content. The sheep were weighed at about 6-8-weekly intervals. RESULTS: Initial liveweight of the sheep was 22.1 (standard error (SE) 1.12) kg and the mean liveweight gains were 270 (SE 22.1) and 170 (SE 12.4) g/day from Days 1 to 94 and 95 to 330, respectively. The mean initial (Day 1) concentration of F in serum was 0.03 (SE 0.005) mg/L, and this changed very little for animals on the low-F diet. In sheep on the high soil-F diet, the concentration of F in serum reached 0.38 (SE 0.021) mg/L at Day 94 but after being placed on the low-F diet concentrations decreased to 0.04 (SE 0.006) mg/L after 14 days (Day 108) and then remained at about this low level for the remainder of the duration of the study. The mean concentrations of F in the humerus and radius of the lambs at Day 1 were 161 (SE 19.4) and 159 (SE 20.4) mg/kg DM, respectively, which increased to 2,784 (SE 80.6) and 1,805 (SE 51.5) mg/kg DM, respectively, at Day 94 in lambs fed the high soil-F diet, then decreased to 1,075 (SE 58.1) and 1,064 (SE 61.6) mg/kg DM at Day 153, and then progressively increased to 1,669 (SE 57.7) and 1,312 (SE 30.8) mg/kg DM at Day 345. CONCLUSIONS: The ingestion of F in soil by sheep markedly increased their concentrations of F in serum and bone, but when the soil was removed and they were fed a low-F diet, concentrations of F in serum decreased to baseline levels within 14 days while concentrations in the bone only decreased to 60-70% of the peak concentration, indicating that some of the F in bone was remobilised.     

Induction of protective immunity to Dictyocaulus viviparus in calves while under treatment with endectocides

Three groups of five parasite-naive calves were used. The treatments were: (a) Group 1 calves were weighed on Day 0 and injected with doramectin at 200 microg/kg. From Day 1 to 19 they were dosed orally with 2000 infective larvae of Dictyocaulus viviparus. On Day 28 they were again injected with doramectin, and infected with D. viviparus larvae from Days 33 to 41. They were then left untreated until Day 81 when they were infected with 20 infective larvae of D. viviparus per kg body weight. They were killed on Day 110 and lungworms were counted; (b) Group 2 calves were immunised with oral lungworm vaccine on Days 0 and 28, and infected and slaughtered as Group 1 on Days 81 and 110, respectively; (c) Group 3 calves acted as infection controls. Blood samples were taken at Days 0, 21, 49, 77 and 110 for antibody tests to D. viviparus. At autopsy there were no significant differences between the number of lungworms from Groups 1 and 2 (Means 17.4 and 31.3, respectively); Group 1 had significantly less value than Group 3 (Mean 228) (p < 0.05). Increased antibody titres to the larval sheath of the infective larvae were observed from Groups 1 and 2, showing that the larvae in Group 1 had penetrated the intestine before being killed by the circulating anthelmintic. This experiment shows that if calves are exposed to infective larvae while under systemic endectocide cover, an immune reaction is stimulated.     

Efficacy of two 65% permethrin spot-on formulations against induced infestations of Ctenocephalides felis (Insecta: Siphonaptera) and Amblyomma americanum (Acari: Ixodidae) on beagles

The efficacy of two formulations of a topically applied 65% permethrin spot-on (Defend Exspot Treatment for Dogs, Schering-Plough Animal Health) was evaluated against experimental infestations of the cat flea Ctenocephalides felis and the lone star tick Amblyomma americanum in dogs. Eighteen dogs were randomly assigned to treatment with 65% permethrin in either diethylene glycol monomethyl ether (DGME; original formulation) or propylene glycol monomethyl ether (PGME) or to be untreated as a control. Treated dogs received either 1 (body weight < 15 kg) or 2 ml (body weight > or =15 kg) of the assigned formulation on Day 0. One hundred unfed, adult C. felis were placed on each dog on Days -6, -1, 4, 11, 18, 25, and 32. Fifty unfed, adult ticks were placed on each dog on Days -1, 3, 9, 16, 23, and 30. Live fleas and ticks were counted and removed on Days 3, 7, 14, 21, and 28. Treatment of dogs with the 65% permethrin in DGME reduced flea numbers by 90.4% to 99.9% from Days 3 through 21 (P < or =.05) and by 48.2% 28 days after treatment. Treatment of dogs with 65% permethrin in PGME reduced flea numbers by 93.7% to 99.7% from Days 3 through 28 and by 78.4% 35 days after treatment (P < or =.05). Treatment with 65% permethrin in DGME reduced tick numbers by 90% or more only on Day 7, whereas treatment with 65% permethrin in PGME reduced the number of live ticks by 90%or more on Days 7 and 14 and approached 90%(87.9%) on Day 21. Efficacy against fleas and ticks for the PGME formulation was significantly better (P < or =.05) than for the DGME formulation on Day 28. Findings in this study indicate that both the DGME and PGME formulations of 65% permethrin performed well in reducing numbers of live C. felis and A. americanum on laboratory beagles; however, the PGME formulation was effective approximately 1 to 2 weeks longer than the DGME formulation.     

Biology and pathophysiology of Toxocara vitulorum infections in a rabbit model

Ten female New Zealand rabbits were infected via stomach intubation with eggs of Toxocara vitulorum at a dosage of 10 embryonated eggs per gram of body weight on Days 0, 35 and 72. Ten or 4% of the administered parasites passed in the feces during the 3 days following the first or second infection, but 32% after the third infection. Many larvae were passed in the third infection, but not in the first or second. Tissue parasite yields were 4.1% on Day 5, 2% on Day 15, 0.8% on Day 30, 0.1% on Day 65 and 0.06% on Day 101. Five hundred and ninety-three larvae were recovered from liver, 243 from lungs and 0 from muscles on Day 5; 282 from liver, 138 from lungs and 21 from muscles on Day 15; 151 from liver, 21 from lungs and 50 from muscles on Day 30; 0 from liver, 26 from lungs and 15 from muscles on Day 65; 0 from liver, 0 from lungs and 9 from muscles on Day 101. No larvae were found in other tissues. The size of the muscle larvae at 30, 65 and 101 days indicated that the parasites did not develop beyond the infective stage and suggested that they were probably hypobiotic organisms. Erythrocytes, packed cell volume and monocytes decreased, but eosinophils and basophils increased, after each infection. Serum enzyme levels indicated that liver damage occured only after the first infection, but muscle injury occurred after each infection and was increasingly more precocious after each infection.     

Relationship between estrous behavior in pregnant mares and the presence of a female conceptus

Unsolicited reports of estrous behavior in mares thought to be pregnant were received from owners or caretakers of Arabian mares. Estrous behavior was confirmed and mares were examined for pregnancy. Gender of the conceptus was determined at foaling in 11 mares in which estrous behavior was confirmed while an apparently viable, ultrasonically normal-appearing conceptus was present. In 9 mares in which the day of ovulation was known (Day 0), the estrous behavior occurred on Day 12, 13 or 14 (5 mares), Day 18 or 20 (2 mares), Day 40 (1 mare) and Day 60 (1 mare). In another study, 55 pony mares were observed for estrous behavior every 3 days for 20 minutes during Days 11 to 40. Estrous behavior was observed in 1 mare (2%) on Day 24. Combined for the 2 studies, the incidence of a female conceptus (12/12) was greater (P<0.01) than the incidence of a male conceptus (0/12) in mares that exhibited estrous behavior.     

Immunity to Toxocara vitulorum repeated infections in a rabbit model.

Eleven rabbits were infected with 10 embryonated eggs of Toxocara vitulorum per g body weight on Days 0, 35 and 72. Embryonated eggs and larvae were enumerated in feces on Days 1-3 after each infection. Two rabbits were killed and larvae were enumerated in small intestine, liver, lungs, skeletal muscles, heart, kidney, brain, eye, uterus, and mammary glands on Days 5, 15, 30, 65 and 101. Serum was obtained on Days 0, 5, 15, 30, 42, 50, 65, 78, 86 and 101 to perform enzyme-linked immunosorbent assays (ELISAs) and Western blots against an extract of embryonated eggs. Between 4 and 10% of the administered parasites, almost all embryonated eggs, were found in the feces after the first or second infection, but 32% (27% of them larvae) after the third. Yields of tissue parasites were 4.1% of the administered dose on Day 5, 2% on Day 15, and 0.8% on Day 30 of the first infection, 0.1% on Day 30 of the second infection, and 0.06% on Day 30 of the third. Larvae were found only in liver, lungs and muscle, including heart. Larva content declined steadily in liver and lungs from Day 5 to 30 of the first infection, was absent in the liver at Day 30 of the second, and in both organs at Day 30 of the third. Muscle larva content increased from Day 15 to 30 of the first infection, and persisted throughout the third infection. Production of IgM antibody was minimal, IgG and the sum of IgMGA antibodies increased slightly or moderately after the first and second infections, but dramatically after the third. Western blots revealed the first antigens (12) by Day 15 of the first infection. Their total number increased with time and number of infections, but some antigens disappeared, whereas new antigens appeared in the course of the observations. Four antigens (32,500-41,000 mol.wt.) may be related to protection. Comparison of the Western blot patterns of two rabbits showed differences in the antigens, recognizable for each rabbit.