Biomedical subjects

R Fayer

Publications and source records attributed to R Fayer.

At least 181 records · Page 10Linked to original sources

PubMed1976

Development of Isospora begemina in dogs and other mammals.

The life-cycle of canine Isospora bigemina was studied in dogs, cattle, cats and mice. Under experimental conditions dogs served as both definitive and intermediate hosts. Unsporulated oocysts (11 X 12 mum) were shed in the faeces and sporulated outside the host within 12 h at 30-37 degrees C and 36 to 48 h at 23 degrees C. Sporulated oocysts measured 12 X 13 mum and contained 2 sporocysts which in turn contained 4 sporozoites. Sporocysts averaged 6 X 9 mum and sporozoites averaged 2 X 6 mum. Although no stages were found microscopically in tissues or in faeces of 23 dogs orally inoculated with sporulated oocysts, the oocysts were infectious because 5 of 14 dogs that ingested tissues of dogs fed oocysts, shed oocysts. Prepatent periods were 7 to 15 days; patency was 1-3 days. No dogs became ill. In the naturally infected dog and one experimentally infected dog, schizonts were found in epithelial cells, distal to the host cell nucleus at the tips of villi throughout the small intestine. Schizonts were 5-7 mum and contained 3-12 merozoites. In the naturally infected dog, gametes were found in the same location. Male gametocytes were 6-8 mum and contained 6-12 microgametes, and female gametes were 7-8 mum. Sporulated I. bigemina oocysts from a naturally infected dog were not infectious to cattle, cats or mice. Structurally identical oocysts were shed by 2 dogs after ingesting hearts and diaphragm from naturally infected cattle; these oocysts were also not infectious to cattle. Although dogs acted as both intermediate and definitive hosts under experimentation, this is not likely to occur in nature. A canine-bovine-canine cycle would appear to be the natural mode of infection but I. bigemina was not infectious to cattle under experimental conditions.

Animals↗

PubMed1976

Abortion and other signs of disease in cows experimentally infected with Sarcocystis fusiformis from dogs.

Six five- to eight-year-old multiparous cows were given oral inoculations of sporocysts of Sarcocystis fusiformis five to six and one-half months after field breeding. All cows became ill. Clinical signs of infection included muscle tremors, hypersalivation, reduced consumption of feed, weight loss, excessive shedding of hair, elevated temperature, reduced packed cell volumes and total red blood cell counts, and abortion. One cow aborted on day 41 after inoculation, and another aborted on day 69. A moribund cow was sacrificed, and a normal fetus was found in utero. Two cows did not produce calves; in one of these cows, a fetal skeleton was found in utero at postmortem examination. One cow produced a normal healthy calf. No evidence of congenital transmission of S. fusiformis was found in histologic specimens from the fetuses or the calf. No illness or abortion was observed in any of the 25 uninoculated control cows. This paper is the first report of bovine abortion associated with experimentally induced sarcocystosis.

Abortion, Veterinary↗

PubMed1976

Possible species differences between Sarcocystis from mule deer and cattle.

In preliminary studies with Sarcocystis from bovine (Bos taurus) and mule deer (Odocoileus hemionus hemionus), a coccidia-free laboratory dog (Canis familiaris) and captive coyote (Canis latrans) were fed flesh from a local Sarcocystis-infected bovine and later flesh from an infected mule deer from Eastern Oregon. Sporocysts were passed in the feces of both canine hosts 10-15 days after ingestion of infected meat. There was a statistical difference in the size of sporocysts derived from bovine and deer. It was concluded that the Sarcocystis from bovine and mule deer probably constitute distinct species with a life cycle dependent on the respective ruminant host and a canine host.

Animals↗

PubMed1976

Effect of monensin on experimental infections of Eimeria ninakohlyakimovae in lambs.

Two nearly identical experiments were conducted to determine the effects of the coccidiostatic compound monensin on Polled Dorset lambs experimentally infected with oocysts of Eimeria ninakohlyakimovae. Prophylactic medication at a dose level of 1 mg/kg of body weight was started 2 days before inoculation and prevented diarrhea and reduced oocyst production. Therapeutic medication at a dose level of 2 mg/kg, started with the appearance of signs of infection, reduced oocyst production below that of nonmedicated controls but did not eliminate diarrhea. Weight gains of medicated lambs were less than those of noninoculated, nonmedicated controls in both experiments. Apparently monensin, at the dose levels used, reduced oocyst production but also prevented weight gains as high as those in inoculated nonmedicated controls.

Animals↗

PubMed1976

Oral infection of mammals with Sarcocystis fusiformis bradyzoites from cattle and sporocysts from dogs and coyotes.

Individual sporocysts containing 4 sporozoites were shed in the feces of dogs, foxes, and raccoons after ingestion of bovine tissue infected with Sarcocystis fusiformis bradyzoites. No sporocysts were shed by cats, monkeys, swine, skunks, ferrets, rats, guinea pigs, or rabbits after ingestion of similar bovine tissue. The shedding of sporocysts by dogs that had ingested tissue from a bovine experimentally infected with sporocysts from coyotes indicated that both canids were definitive hosts for the same species of Sarcocystis. After oral inoculation wtih sporocysts from dogs previously fed infected bovine heart, a calf became infected; but sheep, swine, rats, mice, rabbits, and monkeys did not. These results show the narrow specificity of the asexual stages of this parasite for the bovine intermediate host and the wider, though still restricted, host range of the sexual stages of this parasite for coyotes, dogs, foxes, and raccoons, the definitive hosts.

Animals↗

PubMed1975

Sarcocystis fusiformis infection in the coyote (Canis latrans).

Of 150 fecal samples from coyotes from northern Utah and southern Idaho, 21 contained coccidian sporocysts. These were found singly, contained four sporozoites and a granular residuum, and averaged 16.9 x 10.9 mum in size. None of four lambs inoculated with these sporocysts showed clinical signs of disease, and no parasites were found in their tissues. One calf inoculated with 135,000 sporocysts and another inoculated with 720,000 sporocysts eventually became unable to rise from recumbency. One was killed after 43 days; the other died at 50 days. Both calves had a mild mononuclear cell infiltration into the connective tissue adjacent to vessels in the heart, other striated muscles, kidney, and liver, and a moderate lymphoid hyperplasia in the spleen and lymph nodes. Schizonts were observed in a lymph node, and young sarcocysts were observed in skeletal and cardiac muscles. Four coyotes fed bovine heart infected with Sarcocystis passed sporulated sporocysts in their feces that were indistinguishable from those in the fecal samples from Utah and Idaho.

Animals↗

PubMed1975

Experimentally induced sarcocystis infection in calves: pathology.

Calves fed sporocysts of Sarcocystis isolated from the feces of dogs and coyotes became anorectic, lost weight, and became anemic and prostrate, and died. The most severe pathologic changes occurred between 26 and 33 days after infection; schizonts were found throughout the body. Schizonts were not found after this time. Sarcocytis cysts were in skeletal and cardiac muscles between 33 and 54 days. Necropsy revealed lymphadenopathy, paleness of the mucous membranes and visceral organs, ascites, hydrothorax, hydropericardium, and serous atrophy of fat. Ecchymotic or petechial hemorrhage was in heart, brain, serosa of the alimentary tract, and urinary bladder. Microscopic changes observed in nearly all calves consisted of hemorrhage, mononuclear cell (primarily lymphocytic) infiltration and edema in heart, brain, liver, lung, kidney, and striated muscle. Necrotizing myocarditis with dystrophic calcification of the striated muscle and fat, as well as nonsuppurative inflammation of meninges and glial nodules in the brain, was observed in several calves.

Adipose Tissue↗

PubMed1975

Effect of amprolium on acute sarcocystosis in experimentally infected calves.

Twelve calves were used to determine whether treatment with amprolium affected the severity of experimental Sarcocystis fusiformis infections. In each of 2 experiments, 2 calves received an oral dose of amprolium at 100 mg/kg of body weight for 30 days, 2 calves were similarly inoculated but received no medication, and 2 calves served as uninoculated, unmedicated controls. Data from overall weight gains, packed cell volume, body temperature, postmortem and histological examinations, and serum enzyme levels indicate that amprolium reduced the severity of experimental sarcocystosis.

Amprolium↗

PubMed1975