Experimental infection of dogs with Brucella abortus: effect of exposure dose on serologic responses and comparison of culture methods

Two studies of experimentally induced Brucella abortus infections in dogs are reported. Twenty dogs in experiment 1 were fed approximately 4.8 X 10(10) colony forming units of B. abortus strain 2308 (BA 2308), and 11 dogs in experiment 2 were fed approximately 3.4 X 10(14) BA 2308. Serum samples from each infected dog and noninfected control were tested on the day of infection and at weekly and biweekly intervals post-infection (PI) for antibodies to B. abortus. The standard tube agglutination (STA) and rivanol (RIV) mean log-titers of the infected dogs in the 2 experiments were compared statistically on the day of infection and on PI days 7, 14, 21, 35, 42 and 49. The STA and RIV titers of the infected dogs in experiment 2 were significantly higher than were those of the dogs in experiment 1. Brucella abortus was isolated from 29 infected dogs in experiments 1 and 2 including 10 dogs, which were seronegative when cultured.

Further characterization of the biology of Hammondia heydorni

Hammondia heydorni oocysts, recovered from the diarrheic feces of a dog suffering from corticosteroid toxicosis, were sporulated and characterized morphometrically. Sporulated H. heydorni oocysts were administered to three dogs, five goats, a calf and three guinea pigs, and tissues from these inoculated animals fed to coccidia-free dogs to determine species susceptibility to H. heydorni. Morphometric characteristics of H. heydorni oocysts were similar to previous descriptions. Oocysts were not excreted in the feces of dogs inoculated with oocysts. Dogs fed tissues from goats killed 14, 28 or 42 days after inoculation (d.a.i.) with oocysts excreted H. heydorni oocysts in their feces after consuming goat tissues. Dogs fed tissues from a calf killed at 28 d.a.i., and from goats killed 21 and 56 d.a.i., did not excrete oocysts in their feces. Developmental stages of H. heydorni were not observed in histologic sections of tissues from any of the animals.

Experimental infection of dogs with Brucella abortus

Thirteen female dogs, which included eight principals that were fed approximately 4.4 X 10(10) colony forming units (cfu) of Brucella abortus strain 2308 and five sentinels that were housed with the principals, were examined for serologic responses, blood culture, tissue distribution of the organisms and pathologic lesions. Serum samples from each dog were tested on the day of exposure and on post exposure days 5, 7, 10, 14, 21, 28, 35, 42 and 49 for antibodies to B. abortus, using the brucellosis card (BC), standard tube agglutination (STA), 2-mercaptoethanol (ME) and rivanol (RIV) tests. Antibodies were detected in the principals by day 5 and increased through day 21. The STA test was the first to become positive, followed by the BC, ME and RIV tests. After 28 days, the serologic titers receded. From day 14 through day 42, all principals had greater than or equal to 1:50 STA titers. On day 49, seven principals had greater than or equal to 1:50 STA titers and one had a 1:25 STA titer. The sentinels were negative for all tests, except sentinel number 9 which had STA titers ranging from 1:25 to 1:50 on day 14 through day 35. Blood cultures that were obtained from each principal at intervals from one hour after exposure through 49 days were negative. Brucella abortus was isolated from various lymph nodes of the eight principals and from sentinel number 9, which was apparently infected by ingesting brucellae contaminated feces from the principals. Microscopic lesions were not observed in the culture-positive tissues examined.

Levamisole toxicosis in a dog

A single oral dose of levamisole hydrochloride given at the rate of 12 mg/kg was believed responsible for bradycardia, tachypnea, hypothermia, cerebrocortical depression, and diarrhea in a dog. Supportive treatment and symptomatic treatment for the bradycardia were required for 4 days. In addition to these previously reported abnormalities associated with levamisole toxicosis, cerebrocortical depression and multiple foci of irritation were characterized by electroencephalography.

Photoinduced buphthalmic avian eyes: II. Continuous darkness

Chickens raised from 2 to 14 weeks of age in continuous darkness (OL:24D) developed shallow anterior chambers and buphthalmos (megaloglobus). Chickens raised in continuous darkness developed ocular changes similar to that reported in chickens raised in continuous fluorescent and incandescent light and in dim light. Corneal diameters and axial globe lengths were an inconsistent means of documenting ocular enlargement. Iridocorneal angles were narrowed on scanning electron microscopy (SEM). Intraocular pressure (IOP) was not different from control chickens. The chicken is proposed as a model to study ocular development, the effects of lid suture on infants, axial myopia, preglaucomatous changes, and possibly pharmacologic effects of antiglaucoma preparations.

Experimental infection of gray foxes (Urocyon cinereoargenteus) with Brucella abortus

Ten gray foxes, eight principals that were fed approximately 4.4 X 10(10) colony forming units of Brucella abortus strain 2308 and two controls, were examined for serologic responses and tissue distribution of the organisms. Blood sera from each fox were tested on the day of exposure and at seven weekly intervals for antibodies to B. abortus, using the brucellosis card, standard tube agglutination, 2-mercaptoethanol and rivanol tests. Control foxes were serologically negative for all tests throughout the study and the principals were negative prior to exposure. On days 14, 21 and 28, the eight principals had positive card reactions and greater than or equal to 1:100 tube agglutination titers. After 28 days, the titers receded; and by day 49, three principals had negative card reactions and one of these was negative for all tests. Brucella abortus was isolated from one or more lymph nodes from seven of eight principals including the one which was seronegative. The bacterium was not isolated from lungs, livers, spleens, kidneys, uteri or testicles.