Abstract. Beginning in summer 1977 and continuing through four consecutive seasons, we examined lame limb joints from 106 partially fattened cattle and 28,235 pairs of occipital condyles from fully fattened cattle for osteochondrosis. Of the 106 lame cattle, nine (8.5%) had characteristic lesions, usually in their stifle joints, and of the 28,235 atlanto-occipital joints, 1063 (3.8%) had lesions on their condyles.Slices of affected articular cartilage and subjacent bone were studied radiographically and histologically. Radiographs showed subchondral defects and epiphyseal "cyst-like" lesions, and histologic sections showed disarrayed and degenerated chondrocytes. Splits occurred along osteochondral junctions or in adjacent cartilage or bone. Some bone trabeculae had been replaced by fibrous tissue that, in some areas, extended deep into epiphyses.Osteochondrosis, a degenerative change in articular and growth plate cartilage of rapidly growing animals, is characterized clinically by prolonged limb lameness, and anatomically by disarray of chondrocytes, inadequate provisional calcification of cartilage, failure of endochondral ossification, retention of cartilage, and splits in cartilage and bone [3].Beginning in summer 1977 and continuing through four consecutive seasons, we examined small samples of limb joints and large samples of atlanto-occipital joints from slaughtered cattle for arthropathies and found this disease. Materials and MethodsMost cattle were Hereford, Angus, Charolais, and their crosses. Steers predominated. Their ages at slaughter ranged from 15 to 18 months. All had been fed high concentrate rations in feedlots of eastern Colorado, western Nebraska or western Kansas. They were slaughtered at one of three companies under federal inspection. Cattle with osteochondrosis were of two categories: those with limb joint lesions and lameness, and those with atlanto-occipital joint lesions and no recognized clinical signs. Some had become lame during the fattening period and were slaughtered prematurely for recovery of value. All others had been fattened through 90 to 140 days.During each of the four seasons, a sample of at least 25 lame cattle and a sample of nearly 529

Recombinant rat growth hormone (rrGH) and recombinant mouse growth hormone (rmGH) were developed to evaluate the potential carcinogenicity of each biologically active growth hormone (GH) as assessed in the respective species. Biological activities of rrGH and rmGH were demonstrated by showing an increase in body weight gain and serum levels of insulin-like growth factor-1 (IGF-1) in hypophysectomized rats receiving daily sc injections for 6 days. With the exception of pharmacologically mediated weight gain, rrGH and rmGH had no adverse effects in 5-week oral toxicity studies and no production of anti-recombinant GH antibodies. The high doses selected for the carcinogenicity studies provided systemic exposures of GH up to approximately 10-fold over basal levels. In the 105-week mouse carcinogenicity study, daily sc injections of rmGH at 0.1, 0.2, or 0.5 mg/kg/day were well tolerated and had no effects on survival or incidence of tumors. In the 106-week rat carcinogenicity study, daily sc injections of rrGH at 0.2, 0.4, or 0.8 mg/kg/day had a favorable effect on longevity in female rats administered 0.4 or 0.8 mg/kg/day, an increased weight gain in females and males, and no increase in the incidence of tumors. The absence of carcinogenic effects of recombinant GH administered daily for 2 years to rodents was consistent with publications of clinical experience, indicating a lack of convincing evidence for an increased risk of cancer in children receiving human recombinant GH replacement therapy.

The Scientific and Regulatory Policy Committee of the Society of Toxicologic Pathology (STP) appointed a working group to address risk assessment for increases in alveolar macrophages following inhalation of pharmaceutical materials. This position paper provides recommendations for inhalation study-specific terminology and interpretation based on literature and information from marketed inhaled drugs. Based on a weight-ofthe-evidence approach, and with appropriate consideration of the physical and pharmacological characteristics of the compound, uncomplicated increases in the size or number of alveolar macrophages in nonclinical species are interpreted as nonadverse.

Abstract. Of 30,444 larynges from fattened cattle at three companies, 3,985 (13.1%) had contact ulcers or ulcer scars in the mucous membranes over the vocal processes and medial angles of the arytenoid cartilages. The incidence was higher in cattle fed during fall than in cattle fed during other seasons. We hypothesize: 1. that some feedlot cattle develop acute mucositis from mixed infections with species of Pasteurella, Haemophilus, Mycoplasma, and viruses in the nose, pharynx, and larynx; 2. that reflex coughing and swallowing accelerate the rate of larynx closure; and 3. that the closures erode the swollen membrane over the vocal processes and medial angles of the arytenoid cartilages and thus produce primary contact ulcers.Laryngeal ulcers, either unilateral or bilateral, develop in mucous membranes over the arytenoid cartilages. These lesions, apparently benign and lacking clinical manifestations, have received slight attention in science laboratories and infrequent mention in veterinary literature. In acute stages, however, they may inhibit eating, retard weight gain, and acquire infections, and thus cause economic losses to producers, packers, and consumers.Beginning in summer 1977 and continuing through four consecutive seasons, we examined larynges from fattened cattle at slaughter. This report enumerates and describes the ulcers. Materials and MethodsThis investigation was conducted at three eastern Colorado meat packing establishments: Companies 1, 2, and 3. Each company killed about 2,000 cattle per work day throughout the year. All operations were conducted under federal inspection.Most cattle were Herefords, Angus, Charolais, and their crosses. They had been fed for 90 to 140 days on high-concentrate rations in feedlots in eastern Colorado, western Nebraska. and western Kansas. Their ages at slaughter ranged from 15 to 18 months. Most carcasses were graded good or choice. Soon after arriving at a feedlot, most cattle were vaccinated against infectious bovine rhinotracheitis and leptospirosis, implanted with anabolic pellet, and 667