Transplacental Neospora caninum infection in dogs

A Beagle bitch was inoculated SC and IM with 1.5 million Neospora caninum tachyzoites on the 35th day of gestation. Eight pups were born alive 28 days after N caninum inoculation of the bitch. Pup 1 did not breathe and died while still enclosed in fetal membranes. Pup 2 died 2 days after birth (DAB). Pups 3, 4, and 5 were euthanatized on 2, 3, and 20 DAB, respectively, because they were hypothermic and not nursing. Pups 6, 7, and 8 remained clinically normal. Indirect fluorescent N caninum serum antibody titers were: less than 50 (pups 1 and 8 at 17 DAB, and the bitch before inoculation), 50 (pups 2 and 3 on 2 DAB), 200 (pups 6 and 7 on 17 DAB), and 800 (bitch on day 17 after parturition). Neospora caninum was recovered in cultured cells inoculated with placenta and tissues from all 5 pups necropsied, and N caninum was seen in histologic sections of the heart of pup 5. Results indicate that N caninum can be transplacentally transmitted in dogs.     

Pathogenicity of minute virus of canines (MVC) for the canine fetus.

Minute Virus of Canines (MVC) was shown to cause transplacental infections with embryo resorptions, especially in dams given parenteral inoculations prior to gestational day 30. Responses to oral-nasal inocula were inconsistent. Direct exposures of embryos or fetuses to MVC via the amniotic sac, however, resulted in their deaths after an incubation period of approximately 2 weeks. Virus was prominent in fetal lung and small intestinal villi, but it could not be demonstrated in fetal or uterine tissues greater than 2 weeks after the estimated time of embryonic/fetal death. With 1 exception, dams inoculated during the last trimester of pregnancy gave birth to normal pups; some pups had developed active immune responses. The exceptional dam whelped dead or dying pups with anasarca or myocarditis. Antibody levels to MVC were generally higher in dams with infected fetuses than in bitches with normal pups at term. Failures to isolate virus, or demonstrate viral antigens in tissues by immunostaining, other than near the time of embryo/fetal death, indicate the need for more sensitive viral detection methods.     

Fenbendazole treatment of pregnant bitches to reduce prenatal and lactogenic infections of Toxocara canis and Ancylostoma caninum in pups

A granulated formulation of fenbendazole was tested in a total of 23 treated and control, pregnant, parasite-free Beagle bitches experimentally infected with Toxocara canis and Ancylostoma caninum. The drug was administered to each treated bitch once daily in canned dog food at a dosage of 50 mg/kg body weight. Each of 2 treatment regimens tested was initiated on the 40th day of pregnancy. One regimen involved daily treatment continuing through the 14th postpartum day, and it resulted in 89% fewer ascarids and 99% fewer hookworms in pups born to medicated bitches, as compared with pups born to unmedicated controls. The other regimen of treatment, which was stopped on the day of parturition, was less effective in reducing ascarid and hookworm burdens (64% and 88% reductions, respectively). Three to 5 bitches from each of the treatment and control groups were allowed to whelp a 2nd litter without further treatment or further exposure to parasite infections. Hookworm burdens in 2nd-litter pups born of bitches that had initially received fenbendazole through the 14th postpartum day were significantly lower (P < 0.01; 85% reduction), when compared with the 2nd-litter control pups. All other parasite burdens were not significantly different. It was concluded that granulated fenbendazole is effective in reducing burdens of Ancylostoma caninum and Toxocara canis in newborn pups when the bitch is treated during the last third of pregnancy, especially when treatment (50 mg/kg/day) extends from the 40th day of pregnancy through the 14th postpartum day.     

In utero infection of swine fetuses with infectious bovine rhinotracheitis virus (bovine herpesvirus-1)

The pathogenesis of infectious bovine rhinotracheitis (IBR) virus (bovine herpesvirus-1) was studied in porcine fetuses after in utero inoculation. Laparotomies were performed on 8 seronegative pregnant sows at 34 to 86 days of gestation, and all fetuses in 1 uterine horn of each sow were exposed to IBR virus via inoculation into the amniotic sacs. Fetuses in the other horn served as controls. Clinical signs of infection were not observed in the sows, except for 2 sows that aborted at postinoculation days (PID) 11 and 15. Fetuses of the remaining 6 sows were collected at slaughter on PID 15 to 28. Fetuses were examined for gross abnormalities, presence of IBR virus in tissues, and the formation of neutralizing antibodies to IBR virus. Of 33 inoculated fetuses from 6 sows, 10 were mummified, 11 were hemorrhagic and/or edematous, and 12 were alive. Necrotic lesions were observed on the skin and in the liver of dead and live fetuses. Virus was recovered from 29 of 33 inoculated fetuses. Infectious bovine rhinotracheitis virus was isolated from fetal skin, liver, lungs, kidney, spleen, stomach contents, brain, amniotic fluid, and placenta. Virus was isolated from 4 of 11 fetuses recovered from 1 aborting sow. Antibodies to IBR virus were not detected in sera from the sows. However, antibodies were detected in 6 of 15 fetuses inoculated at 63 to 86 days of gestation and collected at slaughter at 86 to 112 days of gestation. The youngest fetus with detectable IBR antibody was estimated to be 74 days of gestation by measuring crown-rump length of the fetus.     

Efficacy and toxicity of tamoxifen citrate for prevention and termination of pregnancy in bitches

Five groups of bitches were given tamoxifen citrate (1 mg/kg of body weight) orally twice daily for 10 days. Drug administration commenced during late proestrus, day 4 of estrus, day 2 of diestrus, day 15 of diestrus, or day 30 of diestrus (n = 4/group). Nineteen of the bitches accepted natural mating by 1 or more of 3 stud dogs of known fertility (1 bitch did not). Twenty days after cessation of drug administration, ovarian, uterine, and hepatic specimens were obtained from each bitch in 4 of the groups. Pregnancy proceeded to natural termination in bitches of the remaining group (diestrous day 30). Pregnancy was not detected in any bitch of the proestrus, estrous, or early diestrous groups. Of 4 bitches of each of the remaining groups (diestrous day 15 and diestrous day 30), 2 aborted fetuses and/or resorbed placental remnants; the other 2 bitches in each of these groups had normal-appearing fetuses (diestrous day-15 group) or clinically normal pups (diestrous day-30 group). Of the 20 bitches given tamoxifen citrate, 5 developed endometritis with or without pyometra, and 4 of these had ovarian cysts. Although tamoxifen citrate is effective for preventing or terminating pregnancy in the bitch, the regimen used in the study reported here was associated with high frequency of pathologic changes in the reproductive tract.     

An inactivated, oil-emulsion vaccine for the prevention of porcine parvovirus-induced reproductive failure

Pig fetuses inoculated at 45 days gestation with virulent porcine parvovirus (PPV) were harvested 10 days later. Virus was extracted, inactivated with binary ethylenimine and the antigen suspension emulsified with mineral oil adjuvant. One dose of this vaccine, or two doses with a 14 day interval, stimulated high and long lasting serum antibody titres in gilts. Vaccination caused no clinical reactions and lesions at injection sites were minor. Vaccination of seronegative gilts at 40 days gestation caused no adverse effects on fetuses. Six gilts which had been vaccinated five to nine weeks before mating were challenged intravenously with live, virulent PPV at 40 days gestation. At 98 days gestation 78 out of 84 (93 per cent) fetuses were alive and normal and no evidence of PPV infection was found in the six dead (mummified) fetuses. In four unvaccinated gilts similarly challenged with PPV at 40 days gestation only five out of 51 (10 per cent) fetuses survived to 98 days gestation and the virus was detected in 41 of the 46 dead (mummified) fetuses. This vaccine appears to be safe and effective for prevention of PPV-induced fetal loss in gilts.     

Transplacental infection of porcine fetuses following experimental challenge inoculation with encephalomyocarditis virus.

Ten multiparous sows were inoculated between 46 and 50 days of gestation with a fetal swine isolate of encephalomyocarditis virus (EMCV) to investigate the ability of the virus to cause transplacental infection and fetal death. Four sows (group 1) were inoculated IM with EMCV MN-25 that had been passaged 4 times on baby hamster kidney-21 line cell monolayers. Two sows were euthanatized at postinoculation (PI) day 23, and the other 2 sows at PI day 44. An additional 6 sows (group 2) were inoculated IM with the same virus that had been passaged 5 additional times in pigs. Two sows were euthanatized at 14 days, and the remaining 4 sows at PI day 28. Clinical signs were not observed in any of the sows, whereas all sows seroconverted to EMCV. In group 1, only 2 of 50 fetuses were mummified. Virus was not recovered, although EMCV antibodies were detected in the 2 mummified fetuses. In group 2, the 2 sows that were euthanatized at PI day 14 had 26 normal fetuses and there was no evidence of fetal infection. However, in the 4 sows euthanatized at PI day 28, 20 of 48 fetuses were mummified, hemorrhagic, or edematous. Encephalomyocarditis virus was recovered from 21 of 48 fetuses. Transplacental infection and fetal deaths in pregnant sows was achieved following infection with EMCV passaged in pigs.     

Management of apparent luteal insufficiency in a bitch.

Serum progesterone concentration in a pregnant bitch with suspected luteal insufficiency was monitored by use of a commercially available ELISA kit, and exogenous progesterone was administered as needed to enable the bitch to deliver normal-term pups. Progesterone in oil was administered at a dosage of 2 mg/kg of body weight at 72-hour intervals. The bitch delivered 2 clinically normal male pups and 1 mummified female pup within 12 hours after the exogenous progesterone was calculated to have been metabolized.     

Transplacental infection in mice inoculated with Getah virus

Transplacental transmission was demonstrated in pregnant mice subcutaneously inoculated with Getah virus. Viremia was shown in the infected dams, and high-titered virus was detected in the placenta and later in the fetus, suggesting virus invasion of the fetus through hematogenous infection of the placenta. High-titered virus was shown in the fetal brain and muscle and in the brain of the young dying soon after birth. Intrauterine infection resulted in a reduction of the litter size, number of young born alive and survival rate to 1 week of age. These results were further corroborated by necropsy performed several days after virus inoculation. The stage of gestation at the time of virus inoculation greatly influenced these results. Dams inoculated at 12 days of gestation delivered all dead babies, whereas virus inoculation at 5 days of gestation had no effect on the number of young born alive. The dams inoculated at 8 days of gestation had reduced litter sizes and those inoculated at 16 days of gestation produced slightly fewer live babies. Gestational stage at the time of virus inoculation also influenced viral growth in fetuses and placentas. The infection rate was low in dams inoculated at 5 days of gestation, high in dams inoculated at 8 or 16 days of gestation and 100% in dams inoculated at 12 days of gestation. High-titered virus was shown in placentas and fetuses of the dams inoculated at 8, 12 or 16 days of gestation. These results suggest that Getah virus may readily cross the placental barrier through hematogenous infection of the placenta in mice.     

Experimental infection of pregnant goats with swine fever virus

Thirteen pregnant goats were inoculated intravenously with the ALD strain of virulent swine fever (SF) virus on Days 64-84 of gestation. Dams showed transient and mild viremia, and produced high serum neutralizing (SN) antibody after inoculation. Six inoculated dams were reared until parturition occurred and bore six apparently normal, one apparently normal but dead, one mummified and three edematous kids. Neutralizing antibody was demonstrated in the pre-colostral sera obtained from all normal kids, but no SF virus was isolated from any of them. The other seven dams were killed on post-inoculation days (PID) 5-61, and fetuses, placenta and amnion were tested for the virus and SN antibody. All fetuses of five dams examined within PID 40 were positive for SF virus, but negative for SN antibody. SF virus was also isolated from one of three fetuses examined on PID 61. Conversely, the other two fetuses examined on PID 61 were negative for SF virus, but positive for SN antibody. Furthermore, SF virus was isolated from the placenta and amnion of all the dams.     

Lesions in fetal pigs with transplacentally-induced toxoplasmosis

Two sows (Nos. 1, 2) were each fed 1,000 Toxoplasma gondii oocysts. Sow No. 1 was fed oocysts at 60 day of gestation and was euthanatized 49 days later. Sow No. 2 was fed oocysts at day 45 of gestation and euthanatized 62 days later. Sow No. 1 had eight dead fetuses of which one was mummified and unsuitable for histologic study. Sow No. 2 had 11 fetuses, of which four fetuses were mummified and unsuitable for histologic examination, two fetuses were dead and five were live. Lesions and Toxoplasma parasites were identified in seven fetuses from sow No. 1 and three fetuses from sow No. 2. No lesions were found in four fetuses from sow No. 2. Toxoplasma gondii was present in trophoblasts and produced areas of necrosis of the chorioallantois with focal placental separation. The predominant lesions were necrotizing placentitis, non-suppurative encephalomyelitis, and myocardial degeneration, necrosis and mineralization. Numerous tachyzoites were seen in trophoblast cells lining areolae in placenta.     

Real-time ultrasound pregnancy diagnosis in the bitch

A portable real-time ultrasound scanner was used for pregnancy diagnosis in eight bitches. Pregnancy was detected in seven; one bitch was not pregnant. The period between the 28th and 35th days of gestation seemed to be the most suitable time for counting the foetuses. Details of the foetal bodies were clearly visible after the 40th day of pregnancy. Most of the foetuses were detected. Real-time ultrasound can be used for the diagnosis of canine pregnancy as a safe, rapid and easy method, although some inaccuracy in foetal count exists.     

Pathogenesis of in utero infection: experimental infection of eight- and ten-week-old porcine fetuses with porcine parvovirus.

Selected numbers of fetuses in each of 4 pregnant gilts were exposed to a porcine parvovirus by injecting the virus into the allantoic fluid at gestation day 56 or 70. The fetuses were examined on postexposure day 7 or 14. When pregnancy was terminated, 2 of 15 exposed fetuses were dead. Several fetuses tested at post-exposure day 14 had hemagglutination-inhibiting antibodies to porcine parvovirus. Virus was detected most frequently and in highest concentration in the parenchymatous organs of thorax and abdomen of fetuses exposed on gestation day 56. A small amount of antigen was in neurons and capillary endothelium of cerebral and cerebellar cortexes.     

Partial abortion associated with genital Escherichia coli infection in a bitch

A five-and-a-half weeks pregnant Airedale terrier with a genital haemorrhage was presented. It had a history of oestrous irregularities. It was found to be anaemic and Escherichia coli was isolated from vaginal swabs. Oestradiol and progesterone levels were normal. Two fetuses were aborted on day 41 of gestation. Antibiotic treatment was given. The haemorrhage ceased but on day 61 an abnormal vaginal discharge was seen. A caesarean operation was performed from which resulted three dead and two live fetuses, which died within two days. E coli was isolated from the uterine content, although the bitch was still receiving antibiotics; it was also still anaemic. It is probable that the haemorrhage was caused by an endotoxin produced by the E coli. The anaemia in the bitch did not improve the chances of fetal survival.     

Postural Influence on Systemic Blood Pressure in Large Full-term Pregnant Bitches during General Anesthesia

Effects of positioning on systemic blood pressure were evaluated in six full-term pregnant golden retriever bitches during general anesthesia. Two positions (dorsal and left lateral recumbency) were examined. Anesthesia was induced with thiamylal sodium and maintained with halothane in oxygen. Direct arterial blood pressures were recorded from the bitches in each position. Effects of positioning for each bitch during general anesthesia were reexamined after the bitch weaned its pups; thus, each bitch served as its own control. Maternal posture had no significant effect (p greater than 0.05) on systemic blood pressure. Pregnancy had no significant effect (p greater than 0.05) on systemic blood pressure. Supine hypotension did not occur in anesthetized large, full-term pregnant bitches. Dorsal recumbency was an acceptable position for cesarean sections performed with the patient under general anesthesia.     

The intra-uterine position of canine foetuses and their sequence of expulsion at birth

In 14 bitches, laparotomy was performed between the 45th day and 54th day of gestation. In total, 89 foetuses were marked individually by means of transuterine injections of a radiopaque substance. After expulsion, each pup was provided with a colour code. By radiographs one day after birth, all pups of a litter could be identified by the radiopaque markings. In this way the order and presentation at birth of each pup could be compared with the uterine position and presentation at laparotomy. When after expulsion of a pup, one or more were left in each uterine horn, the next pup was produced by the contralateral horn in 43 cases (78·2%) and by the ipsilateral horn in 12 cases (21·8%). One horn was never observed to be completely empty before the other horn started expelling pups. In six of eight bitches in which each two uterine horns did not contain an equal number of foetuses, the first pup was born from the horn containing most pups. The presentation at birth has been observed in 73 pups. For five of these (6·9%), the presentation differed from the one observed at laparotomy; in all five cases the original posterior presentation had changed into an anterior one.     

Effects of prostaglandin F2 alpha-analogue administration on luteal function, implantation of embryos and maintenance of pregnancy in bitches

The present experiment was carried out to clarify the effect of administration of the prostaglandin F2 alpha (PGF2 alpha)-analogue on the luteal function and the maintenance of pregnancy in bitches. Fifty-one bitches received a single inoculation of PGF2 alpha-analogue by intramuscular injection. The effect of this agent was observed by monitoring progesterone (P) levels and the state of the uterus by laparotomy, the occurrence of abortion, and the state of parturition. As a result, when bitches were administered with 100-400 micrograms at the beginning of the luteal phase, the decrease in the P level was temporary. In bitches inoculated with 100-800 micrograms of PGF2 alpha-analogue at the functional luteal stage, the P level began to decrease as early as on the following day after injection. In those treated with 100-200 micrograms of PGF2 alpha-analogue at 10-15 days of pregnancy, pregnancy was maintained in 3 of 5 bitches that had received the treatment at day 10, while in the remaining two, all embryos died after implantation. In those that had received the same treatment at day 15, only 2 of 7 maintained pregnancy. Pregnancy was interrupted in eight bitches treated with doses of 100-200 micrograms at days 25-45. In four bitches treated with doses of 100-200 micrograms at day 55, premature birth was induced after 30-44 hr. In conclusion, regression of the corpus luteum, abortion, and premature birth were induced in bitches treated with 100-200 micrograms at each stage, except the beginning of the luteal phase and of the pregnancy.     

Experimental in utero inoculation of late-term swine fetuses with porcine circovirus type 2.

All 37 fetuses of 3 laparotomized pregnant sows at 86, 92, and 93 days of gestation were inoculated intramuscularly through the uterine wall with porcine circovirus type 2 (PCV-2). The sows were allowed to farrow, and blood and tissue samples were collected from their piglets before and after suckling colostrum. Thirteen fetuses from 2 sows at 90 and 103 days of gestation were used as controls. Of the 37 PCV-2 inoculated fetuses, 24 were grossly normal and 13 were mummified, stillborn, or weak-born at farrowing. Infection with PCV-2 was demonstrated in various tissues of grossly normal and abnormal fetuses by virus isolation, polymerase chain reaction, and immunohistochemical methods. Antibodies specific to PCV-2 were also detected from the sera or thoracic fluids of abnormal fetuses and unsuckled normal pigs. No evidence of PCV-2 infection was found in any control fetuses. The present results confirm previous findings that PCV-2 can infect late-term swine fetuses and may cause reproductive abnormalities.     

Concentrations of progesterone and luteinizing hormone in the serum of diestrous bitches before and after hysterectomy

Blood was collected from 6 adult bitches (3 pregnant and 3 nonpregnant) daily for 59 days after the onset of diestrus, and serum progesterone concentrations were determined. The bitches were hysterectomized at various times during diestrus [diestrus day (DD) 5, 15, or 25] to determine whether the uterus has a role in maintaining luteal function in the pregnant or nonpregnant bitch. Concentrations of serum luteinizing hormone (LH) were also measured to determine whether LH concentrations decrease when luteal function abates (experiment 1). All 6 bitches in experiment 1 had progesterone concentrations greater than 1.0 ng/ml during the 2-month period, indicating that neither the pregnant nor nonpregnant uterus was necessary for maintaining luteal function in the bitch. Concentrations of LH appeared to increase in the serum of 5 of the 6 bitches when progesterone concentrations were declining, indicating that cessation of luteal function does not appear to result from a lack of LH. Blood was collected from the 6 bitches used in experiment 1 twice weekly during the 2nd diestrus after hysterectomy (experiment 2) to determine whether alterations in luteal function that might be observed during experiment 1 were due to some aspect of the surgical procedure, rather than to absence of a uterus. Progesterone concentrations in the serum were lower (P less than 0.05) during the 10 days after surgery in the 2 bitches hysterectomized on DD 5 than in the 4 bitches remaining intact during this period (experiment 1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Observations on transplacental infection with bluetongue virus in sheep

Twenty-four ewes were inoculated with 1 of 2 strains of bluetongue virus type 4 at 40, 60, or 80 days of gestation. Two ewes aborted, 2 ewes died, and 1 was killed during the experiment, but their fetuses were recovered. At term, 2 mummified fetuses, 4 dead lambs, and 17 clinically healthy lambs were produced by 12 sheep, and the remaining 7 sheep were barren. Porencephaly and cerebellar dysgenesis were found in term lambs born to sheep inoculated at 40 and 60 days of gestation. Radiographic examination of 12 fetuses showed developmental ages far less than their chronologic age; 8 fetuses had skeletal growth-retardation lines, which were also observed in the dead lambs. A systemic lymphoreticular hyperplasia was observed in the dead lambs and in all lambs at 12 weeks of age; in 4 of the latter, granulomatous reactions were present in the liver and kidney. Lungs of the full-term lambs were reduced in weight and showed poor alveolar development and mononuclear cell infiltration, which persisted in the 12-week-old lambs. It was concluded that bluetongue virus is capable of causing not only gross abnormalities of the CNS, but also generalized growth retardation and fetal lymphoreticular hyperplasia.