Efficacy of two 65 % permethrin spot-on formulations against canine infestations of Ctenocephalides felis and Rhipicephalus sanguineus

The efficacy of two formulations of a topically applied 65% permethrin spot-on for dogs (Defend EXspot Treatment for Dogs, Schering-Plough Animal Health Corp.) was evaluated against experimental infestations of the cat flea, Ctenocephalides felis, and the brown dog tick, Rhipicephalus sanguineus. Thirty dogs were randomly allocated to treatment with 65 % permethrin in diethylene glycol monomethyl ether (original formulation), 65 % permethrin in propylene glycol monomethyl ether (test formulation), or to an untreated control group. Dogs assigned to treatment with a permethrin formulation received either 1 or 2 ml of the formulation in accordance with label directions on Day 0. One hundred unfed, adult cat fleas and 50 unfed, adult ticks were placed on each dog on Days -1, 5, 12, 19, 26, 33, and 40. Live fleas and ticks were counted on each dog on Days 2, 7, 14, 21, 28, 35, and 42. Treatment of dogs with either formulation of 65 % permethrin significantly (P <.05) reduced the number of live fleas and ticks from Days 2 through 42. No statistical differences were noted between the formulations regarding efficacy against C. felis or R. sanguineus.     

Influence of dietary calcium and phosphorus content in a fixed ratio on growth and development in Great Danes

OBJECTIVE: To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor 1 and parathyroid hormone concentrations, radiography, and blood chemistry analysis results. ANIMALS: 32 purebred Great Dane puppies from 4 litters. PROCEDURE: At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age. RESULTS: Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group. CONCLUSIONS AND CLINICAL RELEVANCE: Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age.     

Histamine production by Haemophilus somnus

Ten Haemophilus somnus isolates were grown on blood agar plates under a 5% CO2 atmosphere for 48 h. Harvested whole cells were washed and evaluated for the presence of histamine by ELISA. All H. somnus isolates had cell-associated histamine concentrations of between 18.5 and 200 ng/ml. In a separate study, the ability of H. somnus to secrete histamine into BHI growth medium was evaluated using H. somnus strains 8025 and 156A as well as a recent 156A respiratory isolate. Each strain or isolate was grown under various concentrations of CO2 to approximate the CO2 concentration in the bronchi. The histamine content of washed whole cells and medium supernatant were determined at various stages of incubation. Highest histamine concentrations were detected in the recent respiratory isolate; whole cells (225 ng/ml) after 120 h incubation in 15% CO2 and supernatant (1721 ng/ml) after incubation for 41 h in 25% CO2. This study indicates that different H. somnus isolates can produce and secrete histamine which may be enhanced by CO2 concentrations which approximate those in the bronchial tree. Results of this study may partially explain some of the post-vaccination reactions occasionally observed with H. somnus bacterins. Additional studies are needed to determine the actual role of H. somnus-derived histamine in the pathogenesis of bovine respiratory disease and airway hyperresponsiveness.     

THE RADIOGRAPHIC APPEARANCE OF PULMONARY HISTOPLASMOSIS IN THE CAT

A retrospective study of 18 cats with pulmonary histoplasmosis was conducted to evaluate radiographic patterns of disease and to determine age, breed, and sex distributions. All cats had active disease confirmed by biopsy/aspiration cytology (lung, bone marrow, peripheral lymph nodes, pleural fluid) or necropsy examination. Cats 3 years of age or less had the highest incidence of disease; females outnumbered males 2 to 1. Radiographically, most cats had an interstitial pattern which appeared as a fine, diffuse or linear pattern, or as a more distinct nodular pattern. An alveolar pattern was an uncommon radiographic finding. Tracheobronchial lymphadenopathy and calcified lymph nodes or pulmonary parenchymal lesions were not identified in these cats.     

Survival of larvae of Boophilus annulatus, Boophilus microplus, and Boophilus hybrids (acari: ixodidae) in different temperature and humidity regimes in the laboratory

The survival period for larvae of Boophilus annulatus (Say), Boophilus microplus (Canestrini) and hybridized Boophilus ticks was determined by exposure to various combinations of temperature (20, 25, 30 and 35°C) and relative humidity (32, 63, 75, 84 and 97% RH) in the laboratory. Results indicated that within a given temperature and RH regime, there was no difference (P > 0.05) in larval survival among the three species tested, indicating that these ticks respond similarly over a wide range of temperature and RH combinations. Larval survival in all three species was longest (P < 0.05) at 20°C and either 84 or 97% RH. With each increase in temperature at the 84 and 97% RH treatment levels, there was a corresponding significant (P < 0.05) decrease in larval survival. When the temperature reached 35°C at all humidities or when the RH was 63% or less at all temperatures, the mean larval survival period was 43 days or less in all cases and little difference (P > 0.05) was observed among the treatment regimes included. Results suggest that at a RH of 75% and more, the temperature is the determining factor in larval survival, whereas at a RH of 63% and less the RH is the determining factor in larval survival, regardless of temperature.     

Photolytic demethylation of monuron and demethylmonuron in aqueous solution

Photochemical demethylation of monuron [3-(4-chlorophenyl)-1, 1-dimethylurea] and of demethylmonuron [ 1-(4-chlorophenyl)-3-methylurea] in aqueous solution was investigated. The photoproducts identified in this study were formaldehyde, formic acid and carbon dioxide. These products indicate that demethylation occurs either by oxidation of a methyl group to hydroxymethyl which is readily cleaved to yield formaldehyde, or by further oxidation to an N-formyl group, which is slowly hydrolysed under weakly acidic conditions to yield formic acid. Samples equilibrated either with air or oxygen (> 99 % purity) gave essentially the same yield of oxidation products. Experimental evidence indicated that extensive photodegradation of formaldehyde was occurring during photolysis, causing low recoveries of formaldehyde. Consequently, with [²H₃-methyl]demethylmonuron and deuterated water, only steady state concentrations of formaldehyde could be measured in an isotopic study.     

Freezing times and temperatures required to kill cysticerci of Taenia saginata in beef

Calves were given viable Taenia saginata eggs by stomach tube and slaughtered 12, 16 or 24 weeks later. The cysticerci-infected carcasses were frozen at six different temperatures for variable lenghts of time. Meat samples were then allowed to thaw at room temperature and the cysticerci were manually isolated. Criteria of viablity of the metacestodes were scolex evagination and peristaltic movements of the bladder wall. Sixteen and especially 12-week-old cysticerci were much more susceptible to the lethal effects of freezing than were 24-week-old cysticerci. The time and temperature combinations required to ensure death of all cysticerci were 360 h at ?5°C, 216 h at ?10°C, and 144 h at ?15°C or lower.     

CERTAIN HEMATOLOGIC AND BLOOD CHEMICAL VALUES IN JUVENILE RHESUS MONKEYS (MACACA MULATTA)

Certain hematologic and clinical chemistry values of 148 rhesus monkeys were determined. Mean values, standard deviations and minimal-maximal values were determined for hemoglobin concentration and packed cell volume; total erythrocyte, total leukocyte and differential leukocyte count; cellular indices; prothrombin time; serum concentrations of glucose, urea nitrogen, uric acid, bilirubin, creatinine, sodium, potassium and chloride, and serum enzyme activities of alkaline phosphatase, glutamic pyruvic transaminase, glutamic oxalacetic transaminase, and lactic dehydrogenase. Calculations were made separately for males and females and the data were compared to published values for the species.