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Special Senses
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kenneth A. Schafer, Oliver C. Turner, Richard A. Altschuler
The ear can be divided into three parts: the external ear, middle ear, and inner ear. The external ear consists of the pinna (auricle) and the external ear canal (external auditory meatus), which ends medially at the external surface of the tympanic membrane (ear drum). The structures of the external ear are supported by auricular cartilage, and the secretions from the sebaceous and ceruminous glands contribute to the formation of cerumen. In rodents, Zymbal’s gland is a sebaceous gland located anterior and ventral to the external ear canal. Pathologic changes of the external ear can involve the skin or specific structures of the external ear (Kelemen 1978). Inflammation of the external auditory canal is usually not an issue in toxicologic studies unless clinical signs, such as shaking of the head or ear scratching, are observed. When inflammation does occur, it is characterized by thickening of the wall of the external auditory canal from edema, and the presence of a tan or brown crusty exudate within the canal (Gad 2007). One cause can be ear mites (e.g., Psoroptes cuniculi in rabbits or Otodectes cynotis in dogs). Auricular chondritis is a spontaneous condition reported in several strains of rats that appears as nodular or diffuse thickening of the pinna by granulomatous inflammation of fibrochondrous to chondroosseous tissue (Chiu 1991; Kitagaki et al. 2003). Differential diagnoses include chondrolysis and neoplasms.
Modern Pharmacognostic Investigation of Harmal
Published in Ephraim Shmaya Lansky, Shifra Lansky, Helena Maaria Paavilainen, Harmal, 2017
Ephraim Shmaya Lansky, Shifra Lansky, Helena Maaria Paavilainen
Shang et al. (2016) on the other hand, chose a true pest, Psoroptes cuniculi, commonly known as the rabbit ear mite, causing havoc in many other domestic animals and of course generating economic losses. They employed microwave extraction of P. harmala seeds to produce an extract, fractionated it by chromatography, and found the extract and the principal components (peganine, harmine, harmaline) acaricidal against P. cuniculi (Figure 7.11).
Crotamiton
Published in M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson, Kucers’ The Use of Antibiotics, 2017
In 1946, Domenjoz described the in vitro efficacy of crotamiton in killing the rabbit ear mite Psoroptes cuniculi. Thirty minutes after immersion in 2% crotamiton, all mites were dead (Domenjoz, 1946). Years later, in vitro and clinical studies demonstrated the efficacy of crotamiton against Sarcoptes scabiei and Demodex mites. One study suggested efficacy against head lice (Karacic and Yawalkar, 1982) and another against pubic lice (Ragheb et al., 1995). As summarized in the Cochrane Database of Systematic Reviews (Strong and Johnstone, 2007), the clinical efficacy of crotamiton for the treatment of scabies is inferior to that of topical permethrin, which has largely replaced crotamiton as the primary therapy globally, with oral ivermectin also now increasingly used.
A single subcutaneous administration of a sustained-release ivermectin suspension eliminates Psoroptes cuniculi infection in a rabbit farm
Published in Drug Development and Industrial Pharmacy, 2018
Mengmeng Lu, Yunpeng Cai, Shizhuang Yang, Qiang Wan, Baoliang Pan
Rabbits are reared for fur, meat, and leather. They are also used as major laboratory animals and pets [1]. China has the biggest rabbit husbandry in the world, providing more than 40% of global rabbit meat and 90% of rabbit fur and leather. Breeding female rabbits are the cornerstones of the rabbit husbandry. The mites Psoroptes cuniculi are one of the most notorious parasites in rabbits, particularly in breeding female rabbits, primarily causing intense pruritus and forming crusts on the ears. These lesions may completely cover the external ear canal and the internal surfaces of the pinna [2]. The infestation can lead to considerable weight loss, low feed conversion rates, anorexia, meningitis, and even death if not properly treated [1]. P. cuniculi may alter the host’s immune response in laboratory rabbits, significantly interfering with the experimental settings and altering the interpretation of final results. The health status of breeding female rabbits has a strong correlation with the viability of bunnies, affecting the development of rabbit husbandry. Furthermore, P. cuniculi also threaten human health (particularly for workers in rabbit farms) due to the risk of zoonosis.