Exophthalmos in ageing rats with Harderian gland disease

Abstract

SummaryExophthalmos was found in aged rats in several longevity studies. Four cases were due to malignant Harderian gland neoplasia whilst others were associated with severe Harderian gland inflammation, less severe inflammation being found in rats without exophthalmos. Keywords: Rats; Harderian gland; Exophthalmos; Corona virus infections; NeoplasmsDuring routine physical examinations of rats in several longevity studies, cases of exophthalmos associated with Harderian gland neoplasia and inflammation were detected. Because both exophthalmos and spontaneous Harderian gland neoplasms appear to be rare in rats (Squire et al., 1978; Altman & Goodman, 1979; Taradach & Greaves, 1984), we examined the Harderian gland of all rats in the colony which developed exophthalmos over a 2 year period. Materials and methodsThe animals in this study were out bred Wistar rats bred at the University of Sydney Animal House, Castle Hill. Rats were housed in stainless steel cages in an air-conditioned room at 27 ± 0·5°C, 50%-75% relative humidity, and were exposed to artificial fluorescent light for 12 h per day. They had free access to tap water and were fed a commercial rat food (Doust & Rabbidge, Sydney, Australia) of composition 53% carbohydrate, 20% protein, 3·2% fat, 3·5% fibre, 1·37% calcium, 0·98% phosphorus and 0·25% sodium, with a calorific value of 12·5 kJ/g.The rats were part of several longevity studies (Everitt, Wyndham & Barnard, 1983;Wyndham, Everitt & Everitt, 1983). Male rats either were hypophysectomized by an intra-aural technique and given 0·5 mg cortisone acetate (Roussel Pharmaceuticals, Sydney, Australia) per 100 g of bodyweight by subcutaneous injection once per week or were sham operated. Some sham-operated rats were given the same amount of food as that consumed by the hypophysectomized rats, which was about 40% of the ad libitum intake of intact rats. A group of intact, non-sham-operated female rats given food ad libitum were also observed. All rats were given individual physical examinations at monthly intervals. Details of the number of rats in each group and the age range in which exophthalmos was detected and the Harderian glands examined are given in Table 1.Affected rats were killed with ether and the contents of the orbit were removed and fixed in 10% buffered formol saline. Sections for histopathology were cut longitudinally through the eyeball and attached Harderian gland and were stained with haematoxylin and eosin (H&E).

Dacryops in a red‐eared slider (Chrysemys scripta elegans): case report

“…The PAS stain revealed seromucoid secretion in the ducts which is reported for the lacrimal gland as opposed to the serous Harderian gland function 21 . Also, we could not identify porphyrin crystals in any section: these are described as characteristic contents of the Harderian gland in rodents 22,23 . The histologic diagnosis of interstitial dacryoadenitis was made.…”

“…The latter is located inferior and anterior to the globe within the orbit 21 . Abnormalities of the Harderian gland may cause exophthalmos 22,23 . Upon histopathologic examination the cystic tissue was determined to derive from the lacrimal gland.…”

Harderian Gland Neoplasms in Captive, Wild-caught Beechey Ground Squirrels (Spermophilus beecheyi)

“…[6][7][8][9][10] The biologic behavior of these tumors varies by species. In mice, Harderian gland adenomas are common in the B6C3F1 strain, with a 4.7% incidence in control males and a 3.3% incidence in control females reported in NTP carcinogenicity studies; carcinomas were reported at a rate of 0.7% in both males and females in the same study.…”

“…1 The function of the gland is poorly understood; while lubrication of the nictitans and cornea is considered to represent the primary purpose of the gland, other proposed roles of the gland and its secretions in mammals include photoprotective effects of the porphyrins, 1 social signaling through pheromones, 2,3 thermoregulation through contribution to pelage lipids, 1,4 and coordination with the pineal-retinal axis through synthesis of serotonin and melatonin. 1,5 Neoplasms of the Harderian gland have been described in several rodent species, including the mouse, 6 rat, 7,8 hamster, 9 and vole; 10 and a single case report in the ground squirrel. 11 Neoplasms may arise spontaneously or as a result of exposure to a variety of chemical carcinogens.…”

Ocular disorders of pet mice and rats

“…A less common cause was orbital neoplasia, such as poorly differentiated adenocarcinoma, solid carcinomas, and poorly differentiated sarcoma (Fig. 2) [25].…”