Abstract
Less Is More
Two-year carcinogenicity studies in rats and mice to test the carcinogenic potential of new drugs remain controversial. Deficiencies in the carcinogenicity study model include variations caused by the use of different animal strains, different sources of animals and diets, as well as the relevance of the results to humans. This excellent review in Veterinary Pathology (“History of Chronic Toxicity and Animal Carcinogenicity Studies for Pharmaceuticals”) details the history of carcinogenicity studies from the 1950s, when contraceptive drugs were first being tested to the present day. Many have questioned the continued need for rodent carcinogenicity studies for pharmaceuticals, and the increase in testing of biologics has caused many to ponder whether carcinogenicity studies are required for biologics at all. In some cases, the available information from knock-out animals, class effects, target biology, and in vitro data may be sufficient to address carcinogenic potential without warranting additional long-term animal studies. In addition, animal rights groups continue to demand that pharmaceutical companies reduce the length of these studies, as well as their use of such large numbers of animals. Recently, the use of transgenic animals for carcinogenicity studies, with the subsequent reduction in length to 6 months, has been promoted.
Mycoplasma Alert in Black Vultures
The complete description of chronic polyarthritis in American black vultures, one of the most common vultures in the New World, reminds us that good classical pathology can provide the best guidance for etiology (“Mycoplasma corogypsi–Associated Polyarthritis and Tenosynovitis in Black Vultures”). This is especially true when considering the confounding problems that arise in natural disease of wildlife. In this report, a combination of gross pathology and histology led to a specific search of mycoplasmal agents and subsequent molecular confirmation. These findings emphasize the value of diagnostic pathology to wildlife management. This report alerts pathologists to investigate thoroughly cases of polyarthritis, which will better establish the infection significance to a species with wide-range distribution, habitat adaptability, and environmental and ecological importance.
Insight Into Canine Cartilage Lesions of the Shoulder
Shoulder joint disease is associated with activity, trauma, diet, and genetics and is frequently noted in humans, horses, dogs, and pigs. Featured in this issue is a canine all-breed, all-age survey (“Age-Associated Cartilage Degeneration of the Canine Humeral Head”), performed to evaluate whether articular cartilage degeneration or osteochondrosis dissecans, indicating faulty enchondral ossification, underlies cartilage lesions to the shoulder. This study challenged the common perception that cartilage defects in the caudal humeral head are the consequence of osteochondrosis dissecans, and it reasoned that older dogs would have more cartilage lesions than those noted in younger dogs, if lesions were due to degenerative joint disease. Every dog submitted for necropsy over the course of a year was evaluated for cartilage lesions of the humeral head. Valuable foundational data were obtained by thorough gross necropsy procedures. Declining autopsy 3 and necropsy rates 1 recorded in our teaching hospitals challenge all pathologists to consider and carefully frame hypothesis-driven investigative studies while also addressing diagnostic concerns.