Effects of steroids on the olfactory function of the dog.

Twenty-four (24) mature, mixed breed, healthy dogs weighing from 14.6 kg to 27.6 kg were used to study the effects of various steroids on the olfactory function of the dog using olfactory detection threshold as an index. Two odorants were used, viz; benzaldehyde and eugenol. Of the various steroids used, only dexamethasone produced classical signs of Cushing's syndrome in the dogs. However, all dogs that received either dexamethasone alone or hydrocortisone plus DOCA exhibited a significant elevation in the olfactory detection threshold for both odorants without any observable structural alteration of the olfactory tissue using light microscopy. On the other hand, neither DOCA, hydrocortisone alone, nor any of the vehicles used in the study significantly altered the olfactory function of the dogs. The results show that Cushing's syndrome can be experimentally produced in dogs using exogenous steroids and that this condition diminishes the olfactory capability of the dog without producing classical signs of the disease.

Controlled dosage titration of febantel paste in naturally parasitized cattle.

A controlled anthelmintic trial was conducted to determine the efficacy of febantel paste (45.5%) at dosages of 2.5, 5.0, 7.5, and 10.0 mg/kg in calves harboring natural gastrointestinal nematode infections. Dosages of 5.0, 7.5 and 10.0 mg of febantel/kg of body weight were greater than 96% effective in removing adults of Haemonchus contortus, Ostertagia spp, Cooperia spp, and Oesophagostomum radiatum. The 2.5 mg/kg dosage was considered suboptimal because of low efficacy against Ostertagia and Cooperia spp. Efficacies against Trichostronglylus axei, Trichuris spp, Bunostomum phlebotomum, and Stronglyloides papillosus were difficult to determine because fewer numbers of these nematodes were recovered. Efficacies of febantel paste against immature bovine parasites ranged from 83.62% to 97.72%.

Anosmia associated with canine distemper.

The sense of smell in dogs infected with canine distemper virus (CDV) was examined by use of EEG olfactometry, behavioral olfactometry, and electro-olfactography. Infection with CDV was confirmed by a direct immunofluorescence technique in 8 active cases and was suggested by clinical history compatible with canine distemper 10 to 26 weeks earlier in 6 cases. Pathologic alterations of the olfactory mucosa in 3 clinically affected dogs was examined by light microscopy. Infection with CDV was found to be associated with anosmia and lack of recorded responses on electro-olfactogram in 8 of 8 dogs with clinical signs of acute distemper from naturally acquired infections. Anosmia was found in 5 of 6 dogs that had recovered from acute distemper 10 to 26 weeks earlier. The sixth dog had hyposmia, with abnormalities on the electro-olfactogram. Histologic examination was not performed on the 6 dogs that had recovered. Histologic lesions observed at necropsy in 3 dogs that had had clinical signs of acute distemper were those of subacute purulent rhinitis and atrophy of the olfactory epithelium. Altered olfactory function could be explained by mucopurulent exudate blocking odors from olfactory receptors in the acutely affected dogs, but alteration of olfactory function in the dogs that had recovered without clinical evidence of rhinitis could not be explained.

Comparison of serologic tests for detection of antigen in canine heartworm infections.

In 30 random-source dogs, we determined sensitivity and specificity of 5 serologic tests for detection of canine heartworm antigens. Seventeen of the dogs were infected naturally with adult Dirofilaria immitis, and 4 of the infected dogs were amicrofilaremic. The ability of the serologic tests to predict whether a dog was infected or uninfected (overall test accuracy) ranged from 73 to 97%. Sensitivity was not affected by circulating D immitis microfilariae, but was markedly influenced by the number of adult D immitis present. False-positive reactions were rare and were not associated with intestinal parasites or Dipetalonema reconditum microfilariae. Modifications of some of the test procedures were necessary to maximize test accuracy and reproducibility. These modifications and other technical details might limit the usefulness of some of the tests in a veterinary practice.

Supernumerary ectopic penis in a bull.

A 1-month-old Beefmaster bull was admitted for removal of a congenital ectopic penis and sheath from the right paralumbar fossa. Gross and histologic evaluation of the excised tissue revealed a normal sheath containing a penis that terminated at a prostate gland, medial to the wing of the right ilium. Rectal palpation of the bull 14 months later disclosed no association between the excised ectopic tissue and the normal genital tract.

Efficacy of fenbendazole-medicated feed blocks against gastrointestinal nematode infections in calves.

An anthelmintic trial was conducted to determine the efficacy of fenbendazole (FBZ) incorporated into two types of feed blocks given daily for 3 or 10 days to calves naturally parasitized with gastrointestinal nematodes. Each treated calf consumed 5 mg of FBZ/kg of body weight. The FBZ was greater than 99% effective in removing adults of Haemonchus contortus, Ostertagia ostertagi, O lyrata, Cooperia punctata, C pectinata, C onchophora, Trichostrongylus axei, Bunostomum phlebotomum, and Oesophagostomum radiatum. Fenbendazole was also greater than 99% effective against immature nematodes recovered from the small intestine, which were thought to be mainly Cooperia spp. Efficacy was similar for FBZ in each of the two types of feed block carriers and for the 3- and 10-day regimens. Calves readily consumed feed blocks containing FBZ and did not have adverse reactions to FBZ.

Dermal cellular responses of helminth-free and Ostertagia ostertagi-infected calves to intradermal injections of soluble extracts from O. ostertagi L3 larvae.

Twelve calves were raised helminth-free until 9 weeks of age when six were orally inoculated with 100,000 Ostertagia ostertagi infective stage larvae (L3). Three uninfected and three experimentally infected calves received intradermal injections of sterile saline and soluble larval extract (SLE) from O. ostertagi L3 with a protein concentration ranging from 1 to 200 micrograms ml-1. Biopsies were performed 48 h post-injection. A kinetic study was performed on the remaining six calves, three infected and three uninfected, using a 100 micrograms ml-1 concentration of SLE and taking biopsies 1, 4, 8, 12, 24, and 72 h post-injection at both the saline and SLE-injected sites. All calves had an immediate wheal and increase in skin thickness at the SLE-injected sites. The numbers of eosinophils infiltrating SLE-injected sites as compared to saline-injected sites were significant in both uninfected and infected calves, but the infected calves had significant numbers to a wider range of SLE concentrations and had significantly higher numbers than uninfected calves in the kinetic study. Infected calves also had significant numbers of basophils in the dose response study at concentrations of 5 and 100 micrograms ml-1 SLE. Neutrophil infiltration was similar in both groups and was significant at SLE-injected sites early in the kinetic study. Detectable mast cells were decreased in SLE-injected sites of infected animals and perivascular accumulation of mononuclear and some polymorphonuclear cells was observed in the deep dermis of infected animals.

Evaluation of three formulations of fenbendazole (10% suspension, 0.5% pellets, and 20% premix) against nematode infections in cattle.

Anthelmintic efficacies of 3 formulations of fenbendazole were evaluated in cattle naturally parasitized with nematodes: a 10% oral suspension, 0.5% pellets as a top dressing on feed, and a 20% premix. All formulations of fenbendazole were greater than 99% effective in removing adults of Haemonchus contortus, Ostertagia spp, Cooperia spp, and Oesophagostomum radiatum. Fenbendazole was greater than 96% effective in removing adults of Strongyloides papillosus and greater than 85% effective in the removal of Trichuris sp. Fenbendazole was greater than 96% effective against immature nematodes, which were thought to be primarily Cooperia spp. Adverse reactions were not observed in calves treated with the 3 formulations of fenbendazole.

Technique for percutaneous pulmonary arterial catheterization in conscious dogs.

A technique was developed to allow percutaneous placement and exchange of pulmonary arterial catheters in conscious dogs. Seven dogs were catheterized weekly for 5 weeks, using a 10-gauge over-the-needle cannula. A No. 7 F flow-directed catheter was passed through the cannula to measure right heart and pulmonary arterial pressures and to calculate cardiac output. The flow-directed catheter was removed and replaced with an arteriographic catheter, and a pulmonary arteriogram was performed. Placement in alternate jugular or saphenous veins each week resulted in successful catheterizations in all dogs evaluated.

Effect of human leukocyte A interferon on prevention of infectious bovine rhinotracheitis virus infection of cattle.

Human leukocyte A interferon was evaluated for its ability to prevent infectious bovine rhinotracheitis virus-induced respiratory tract disease in cattle. Weanling calves were treated daily for 1 week with 50 X 10(6) U of interferon, intranasally (by nebulization) and IM, and inoculated with infectious bovine rhinotracheitis virus on the first day of treatment. Respiratory tract disease was less severe in treated as compared with nontreated calves which were given only infectious bovine rhinotracheitis virus, and infection in the treated calves occurred later than in the untreated calves. Viral shedding and appearance of viral neutralizing antibodies occurred later in treated calves than in calves given only virus. Because several calves in a treatment group were housed together, whether the late appearance of infection in some interferon-treated calves was due to emergence of suppressed virus or to horizontal transmission from calves shedding virus could not be determined. One calf in the interferon-treated group developed antibody to human interferon and a few treated calves had transient elevation of hepatic enzymes. Interferon-treated calves developed a high temperature which subsided on termination of treatment. Production of disease was considerably dependent on the amount of virus and interferon given, since calves given 300 times more virus and approximately half as much interferon showed no evidence of protection against infection.

Experimentally induced Cooperia oncophora infection in calves: lymphocyte blastogenic and delayed hypersensitivity responses.

Lymphocytic responses in peripheral blood and visceral lymph to Cooperia oncophora antigen and skin tests were determined in 35 Holstein male calves that were inoculated orally with single or multiple doses of C oncophora infective larvae. Several calves were vaccinated or given immune serum before larvae were inoculated. Antigen-specific in vitro blastogenesis of blood and lymph lymphocytes and delayed-type hypersensitivity reactions were observed in several inoculated, vaccinated, and/or passively immunized calves. Most calves that had delayed skin reactions also had in vitro lymphocyte responses to C oncophora antigen. The lymphocyte and skin responses were inconsistent and variable in time of onset--the earliest lymphocyte response occurring 7 days after calves were inoculated. A cellular immune response was induced by both dermal vaccination and oral inoculation; however, passive immunization by IV administration of immune serum simultaneously with inoculation did not have an apparent effect on the cellular response, as measured by the lymphocyte blastogenesis test or dermal testing. Although cellular immune responses were observed in several calves infected with C oncophora, there was no apparent relationship between the specific responses and number of nematodes establishing infection in calves after either single- or multiple-dose oral inoculations.

Monensin toxicosis in broiler chickens.

Chickens treated at seven weeks of age with 150, 200, or 250 mg of crystalline monensin sodium/kg body weight had signs of toxicosis, including extreme weakness, anorexia, paralysis and death. Gross lesions included emaciation, generalized congestion, myocardial enlargement and pallor, and hydropericardium. Samples of ventricular myocardium, superficial pectoralis (white fibers), anterior latissimus dorsi (intermediate fibers), and sartorius muscles (mixed red, intermediate, and white fibers) were examined by light microscope. Intermyofibrillar vacuolation, histochemically positive for neutral fat, was severe in the myocardium and red muscle fibers and moderate in the intermediate muscle fibers. Myofiber necrosis was limited to the red muscle fibers. Mitochondrial degeneration was apparent in myocardial sections from several chickens. Interstitial infiltration by macrophages and heterophils was common in the myocardium and aerobic skeletal muscle.