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Biomedical subjects

A C Todd

Publications and source records attributed to A C Todd.

At least 73 records · Page 4Linked to original sources
PubMed1979

Selected clinicopathologic changes associated with experimentally induced Fascioloides magna infection in white-tailed deer.

Six white-tailed deer (Odocoileus virginianus), less than one year of age, were divided into two groups of three each and administered 50, or 500 metacercariae of ascioloides magna. All six deer became infected. Three additional deer of the same age were uninoculated controls. All deer were monitored for up to 43 weeks after inoculation to investigate changes in weight, selected hematologic values, and blood chemistry values. Although clinical disease was not evident in the infected deer, a significant reduction (p less than .01) in hemoglobin and packed cell volume was detected throughout the experiment. A significant elevation (p less than .01) in the total serum protein level was detected in both infected groups from 0 to 5 months after inoculation. Increases were present in the beta and gamma globulin fractions. No differences (p greater than .05) were detected in the serum calcium, magnesium, or phosphorus levels, or in body weights between infected and uninfected control groups.

Animals↗
PubMed1979

Observations on the pathogenic effects of Nematodirus helvetianus in dairy calves.

Six Holstein-Friesian calves 3 to 5 months old, were used in a small-scale experiment to determine the pathogenic effects of the thread-necked strongyle Nematodirus helvetianus. Two calves were kept as controls and 4 were infected, 2 with single doses of 25,000, and 2 with 50,000 N helvetianus larvae. Observations made during the 8 weeks of the experiment found that N helvetianus is capable of producing severe pathologic changes in the intestine of previously healthy calves. At 38 days after infection, the calves infected with 25,000 and 50,000 larvae gained 32.9% and 72.4% less weight respectively, than their controls. An increase in total lymphocytes was observed with no significant change in hemoglobin concentration. Adult worms were found to penetrate the intestinal mucosa with considerable destruction, including tunneling. Rectal temperatures were elevated in infected animals. The prepatent period for N helvetianus in single infection was 18 to 19 days. A spontaneous expulsion of the adult parasites was observed in 1 of the calves exposed to 50,000 larvae. Worms recovered in this animal numbered 565, whereas the number of worms recovered in another calf infected with 50,000 larvae was 21,860.

Animals↗
PubMed1979

Ovine coccidiosis: comparison of the effects of monensin and aureomycin on lambs infected with coccidia.

Lambs naturally infected with mixed species of Eimeria were fed monensin (30 mg/kg of feed) and aureomycin (10 mg/kg of feed) separately and in combination. An evaluation was made of the efficacy of the treatments in the suppression of oocyst production. Comparisons were made of the parasitic damage to the intestinal surface. Performance of the lambs was measured by weight gains and feed efficiency. Monensin given separately or in combination with aureomycin produced decreases in oocyst counts that were not significantly different from those in the lambs given only aureomycin. Body weight gains and feed efficiency were best in the aureomycin-treated group, and less so in the monensin-treated and the control groups. Animals fed the monensin-aureomycin combination had the poorest weight gains and feed efficiency. Scanning electron microscopy indicated that the groups fed monensin or aureomycin separately had morphologically normal intestinal surfaces. This was in contrast to the control group and the group fed the monensin-aureomycin combination, wherein there was disrupted intestinal surface morphology.

Animals↗
PubMed1978

Anthelmintic activities of fenbendazole against Nematodirus helvetianus in cattle: effect on egg production, embryogeny, and development of larval stages.

Calves experimentally infected with Nematodirus helvetianus were treated with a single dose of fenbendazole at the rate of 5 mg/kg of body weight. Fenbendazole was found to have an efficacy of 97.4% against adult N helvetianus. Additionally, eggs recovered 12 hours after calves were given the anthelmintic had fewer and frequently abnormal blastomeres. Fewer eggs were evident at 36 hours after treatment, and none was found at 72 hours or later. On the culturing of eggs from manure passed at 12 hours and later, almost no larval stages developed.

Animals↗
PubMed1977

Further controlled evaluations of fenbendazole as a bovine anthelmintic.

The efficacy of fenbendazole (methyl-5-(phenythio)-2-benzimidazole-carbamate) in cattle parasitized by the lungworm Dictyocaulus viviparus and in other cattle parasitized by Haemonchus, Ostertagia, Trichostrongylus, Cooperia, and Oesophagostomum was investigated in 3 controlled critical experiments. A single treatment with 5.0 mg/kg of body weight administered in the feed or in a 10% suspension exceeded 99% efficacy against these helminths. Dosages of 1, 0.5, 0.35, and 0.25 mg/kg of body weight administered for 5 days to individual calves in their feed were 99% efficacious against all helminths, except Haemonchus. The 1.0 mg/kg dose removed 99.5% of the Haemonchus, and the other 3 dosages had efficacies of 91.0, 93.7, and 95.6%, respectively. The small daily dosages were not evaluated against Dictyocaulus.

Animal Feed↗
PubMed1977

Fascioloides magna in white-tailed deer (Odocoileus virginianus): observations on the pairing tendency.

Fascioloides magna (Bassi 1875) was recovered from 227 of 312 (73%) white-tailed deer (Odocoileus virginianus) in southern Texas between 1971 and 1975. Deer from age classes more than 1 year old had infection rates of from 64 to 84%. Few dead flukes were found. Flukes occurred exclusively in the livers of infected animals and were paired in 256 of 301 (85%) fibrous hepatic capsules. The prevalence of immature flukes with an average of one immature per infected liver was similar in all age classes, suggesting a relationship between fluke pairing and maturation.

Age Factors↗
PubMed1977

Anticoccidial activity of eight compounds in domestic mink.

Eight compounds were tested for anticoccidial activity in 44 domestic mink (Mustela vision). A treatment group consisted of 4 mink exposed to 2 inoculumns of sporulated oocysts on day 0 and day 22 of the experiments. Each inoculum contained 2,000 Isospora laidlawi, 2,000 Eimeria vision, and 2,000 Eimeria sp. One compound was administered to each treatment group; a control of 4 juvenile mink and a control group of 4 adult mink were designated. All treatments were given each day for 30 days after the initial exposure, except lincomycin which was administered for 14 days. In juvenile mink (3 to 4 months old), amprolium at dose level of 0.012% and sulfaquinoxaline at dose level of 0.024% in the water inhibited almost all of the oocyst production when compared with that of the control group. Lincomycin injected at dose level of 5 mg/day/mink was ineffective in suppressing oocyst production. In adult mink (2 to 4 years) monensin sodium at dose level of 0.012% a commercial antiobiotic-sulfonamide mixture at dose level of 0.49%, and lasalocid solium at dose level of 0.01% in the feed inhibited almost 100% oocyst production. Lasalocid sodium at dose level of 0.10% in the feed was lethal to 3 to 4 mink. Sulfamethazine at dose level of 0.014% and sulfathiazole at 0.014% in the feed had limited anticoccidial activities.

Amprolium↗
PubMed1976

Effects of six fasciolicides against Fascioloides magna In white-tailed deer.

Thirty-three white-tailed deer (Odocoileus virginianus) of various ages, both sexes, and in good physical condition were captured for anthelmintic evaluation of six compounds against the large American liver fluke, Fascioloides magna. Based on fluke mortality, hexachlorophene administered at the rate of 12 to 26 mg/kg of body weight was lethal to 5 of 10 mature flukes in seven deer. Nitroxynil at 11 to 24 mg/kg inhibited egg production, but did not kill mature flukes in eight deer. Rafoxanide at 12 to 25 mg/kg killed 6 of 8 (75%) immature flukes in eight deer, but was not effective against 17 mature flukes. Clioxanide at 16 to 38 mg/kg, diamphenethide at 255 to 280 mg/kg, and hexachloroethane at 463 to 629 mg/kg were not effective against F. magna in four, two and four deer, respectively. There was no indication that treatment with fasciolicides at the higher dose rates was more efficacious than at the lower dose rates. Detection of fluke eggs in the feces was a reliable method for diagnosing the presence of mature F. magna in deer prior to treatment, but was not reliable for measuring fasciolicidal activity of all compounds tested.

Animals↗