Diseases in pet degus: a retrospective study in 300 animals

Disseminated histiocytic sarcoma in a degu (Octodon degus)

A 7-year-and-8-month-old, male degu (Octodon degus) with anorexia, depression, and labored breathing was found to have a thoracic effusion and enlargement of the right testis on radiographic examination. Despite treatment, the animal died. At necropsy, hepatomegaly, splenomegaly, and multifocal nodules on the intestinal serosa and mesentery were observed. Histologically, the foci were densely cellular invasive neoplasms composed of sheets of round to polygonal cells, with occasional multinucleated giant cells. Immunohistochemically, the neoplastic cells were immunopositive for ionized calcium-binding adapter molecule 1, human leukocyte antigen-DR, and CD204. These findings were consistent with disseminated histiocytic sarcoma.

Rodent Pediatrics

This article reviews the development, hand-rearing, feeding, housing, and social behavior of common pet rodent species (rats, mice, hamsters, gerbils, guinea pigs, chinchillas, and degus). In addition, common gastrointestinal, respiratory, cardiovascular, dermatologic, musculoskeletal, neurologic, and ophthalmic disorders in pediatric pet rodents are reviewed. Preventative care and indications for spaying and neutering are discussed.

Rodent Dermatology

This article reviews the most common dermatologic conditions of the pet rodent population, including the prevalence, clinical signs, diagnosis, and treatment recommendations.

Comparison of the retrosplenial cortex size between the degu (Octodon degus) and the Wistar rat (Rattus norvegicus)

The degu (Octodon degus) is a rodent that normally constructs burrows for nesting and rearing. To navigate inside these burrows, degus may use idiothetic and/or sensory cues more than visual information, which is less effective in burrows. Spatial information for navigation is processed in several key brain regions including the retrosplenial cortex (RS). However, the structural characteristics of the degu RS have not been previously reported. The present study measured the sizes of the RS and constituent areas 29 and 30 in the degu, and compared these to those found in the rat, which is a terrestrial rodent. The proportion of the rostrocaudal length of the entire RS relative to that of the entire cortex was significantly larger in degus versus rats. The proportion of the rostrocaudal length of the RS at levels rostral to the splenium of the corpus callosum relative to that of the entire cortex was also significantly larger in degus versus rats. Furthermore, the ratio of the estimated volume of area 29 relative to that of area 30 was significantly larger in degus versus rats. These results show that the degu has a rostrocaudally longer rostral RS with a larger area 29 compared to the rat, which suggests that these structural features may be relevant to differences in spatial information processing between the fossorial degu and terrestrial rat.

Spontaneous intranasal tumours in degus (Octodon degus): 20 cases (2007-2020)

OBJECTIVE

The objective of this retrospective study was to describe the clinical and histopathological findings associated with intranasal tumours in degus.

MATERIALS AND METHODS

Medical records of degus diagnosed with intranasal neoplasms on histopathological examination between the years 2007 and 2020 at one hospital were included in the study.

RESULTS MEDICAL RECORDS OF DEGUS

Twenty degus (10 males and 10 females) were eligible for inclusion. Initial clinical signs included sneezing, abnormal nasal sounds, and nasal discharge, followed by anorexia and frequent nose rubbing. On radiography, 15 out of 20 animals showed space-occupying lesions in the nasal cavity. CT was performed in 16 animals and revealed various degrees of changes, including abnormal radiopacity within the nasal cavity and damaged nasal septum. Rhinostomy and excisional biopsy was performed in all 20 animals. Six out of 20 patients died during the perioperative period. Six and seven degus survived for 3 months and 1 year, respectively. One animal was lost to follow-up. In 16 cases the histological diagnosis was consistent with fibromas, while in 4 cases with osteomas.

CLINICAL SIGNIFICANCE

Intranasal neoplasms in degus are mostly benign mesenchymal tumours with various degrees of bone formation, which is unique to this animal species. This occurrence should be considered as an important differential diagnosis for upper respiratory tract disease in degus.

Cardiology in Rabbits and Rodents-Common Cardiac Diseases, Therapeutic Options, and Limitations

Information about heart diseases and their treatment is still sparce for rabbits and rodents. Dilated cardiomyopathy seems to occur more frequently in rabbits, whereas in guinea pigs pericardial effusion is often diagnosed. There are still no available therapeutic studies for heart diseases in rabbits and rodents, and treatment is often extrapolated from dogs and cats. Consideration should be given to the off-label use of drugs, mostly not licensed in the species mentioned in this article.

Use of Micro-CT Imaging to Assess Ventral Mandibular Cortical Thickness and Volume in an Experimental Rodent Model With Chronic High-Phosphorus Intake

Adverse effects of high dietary phosphorus on bone health have been observed in both animal and human studies. The aim of the investigation was to examine chronic effects of high phosphorus diet on the apical mandibular cortical thickness and volume in a hystricomorph rodent (Octodon degus) using microcomputed tomography. Male degus were randomly divided into two groups fed by different mineral contents from the age of 12 weeks till the age of 17 months. The micro-CT scanning and wall thickness analysis were applied on the region of the mandible exactly under the apices of the 4th premolar tooth, first molar tooth, and second molar tooth in two animals from each group. General overview and mapping of the ventral mandibular bone thickness revealed pronounced bony mandibular protrusions in all the animals fed a high-phosphorus diet with obvious bone thinning apically to the 4th premolar and first and second molar tooth apices. Mandibular bone volume and thickness located apically to the premolar and molars were statistically significantly smaller/thinner in the group fed by a high phosphorus diet. The thinnest bone measured 0.004 mm, where the mandibular 4th premolar tooth almost perforated the mandibular cortex. Similar studies of metabolic bone disease and its influence on alveolar bone were also published in rats and mice. The influence of different environmental, infectious, or metabolic factors on the growing tooth, alveolar bone formation, and bone pathologies must be done experimentally on growing animals. In contrast, degus have continuously growing dentition, and the effect of any of the above listed factors can be studied in this animal model at any age and for longer time periods.

Sedation and Anesthesia in Rodents

Sedation and anesthesia in rodent species are complex due to their wide species variation, small size, and metabolism. This review article covers recent advances in sedation and anesthesia as well as an updated drug formulary for sedation protocols. Setup, equipment, monitoring, maintenance, and recovery are reviewed as well as species-specific anatomy.

Respiratory Diseases in Guinea Pigs, Chinchillas and Degus

The diagnosis and treatment of respiratory disease in pet guinea pigs, chinchillas, and degus still face profoundly serious challenges owing to their relatively small size, conspicuous clinical signs, difficulty for sampling, and insufficient scientific evidence to correlate signs and particular pathologies. This article is intended to summarize the available information on the relevant anatomy, physiology, and respiratory pathology in these species.

Case series: Efficacy of a formulation containing selamectin and sarolaner against naturally acquired mite infestations (Demodex sp., Ornithonyssus bacoti) in degus (Octodon degus)

Ectoparasite infestations are not common in degus. Two cases are presented here where use of Stronghold® Plus/Revolution® Plus (selamectin and sarolaner topical solution) was successfully administered to a degu (Octodon degus) for treatment of naturally-occurring mite infesations. Selamectin (Stronghold®/Revolution®) has been demonstrated to be effective against naturally-occurring mite infections in dogs and selamectin is approved for use in dogs for the treatment of sarcoptic mange (caused by Sarcoptes scabiei) at a dose of 6 mg/kg. In the first case, a 2.6-years-old female degu housed in a group with four other degus was presented with pruritic skin reactions, restlessness and hairloss. Mites morphologically similar to Demodex sp. were detected in the deep skin scrapings. All four degus were treated with Stronghold® Plus/Revolution® Plus (30 mg/kg selamectin and 5 mg/kg sarolaner) once a week for a total of six treatments. The spot-on was administered topically on the dorsal cervical region. Following treatment the degu presenting with clinical signs showed a rapid improvement with the pruritus and overall dermatitis resolving within 2 weeks of treatment. Skin scrapes and microscopic examination of epidermal debris collected from the affected degu were negative for mites from day 14 onwards. In the second case, a group of four 4-6.5-years-old female and male degus that were housed together were infested with Ornithonyssus bacoti. All animals were treated with 30 mg/kg selamectin and 5 mg/kg sarolaner in four total weekly doses. One week later no living mites were found on the patients or in their environment. The four degus improved visibly, and within three weeks of treatment the skin lesions associated with the infestation subsided. The antiparasiticides showed a satisfactory efficacy and were well tolerated (n = 9 animals treated in a total).

Octodon degus: a natural model of multimorbidity for ageing research

Integrating the multifactorial processes co-occurring in both physiological and pathological human conditions still remains one of the main challenges in translational investigation. Moreover, the impact of age-associated disorders has increased, which underlines the urgent need to find a feasible model that could help in the development of successful therapies. In this sense, the Octodon degus has been indicated as a 'natural' model in many biomedical areas, especially in ageing. This rodent shows complex social interactions and high sensitiveness to early-stressful events, which have been used to investigate neurodevelopmental processes. Interestingly, a high genetic similarity with some key proteins implicated in human diseases, such as apolipoprotein-E, β-amyloid or insulin, has been demonstrated. On the other hand, the fact that this animal is diurnal has provided important contribution in the field of circadian biology. Concerning age-related diseases, this rodent could be a good model of multimorbidity since it naturally develops cognitive decline, neurodegenerative histopathological hallmarks, visual degeneration, type II diabetes, endocrinological and metabolic dysfunctions, neoplasias and kidneys alterations. In this review we have collected and summarized the studies performed on the Octodon degus through the years that support its use as a model for biomedical research, with a special focus on ageing.

Spontaneous Tumors and Non-Neoplastic Proliferative Lesions in Pet Degus (Octodon degus)

In recent years, degus (Octodon degus), rodents native to South America, have been becoming increasingly popular as pet animals. Data about neoplastic diseases in this species are still sparse and mainly limited to single-case reports. The aim of this study was to present neoplastic and non-neoplastic proliferative changes in 16/100 pet degus examined at the Veterinary Faculty University of Ljubljana from 2010 to 2015 and to describe the clinic-pathological features of these lesions. Twenty different lesions of the integumentary, musculoskeletal, genitourinary and gastrointestinal systems were diagnosed: amongst these were 13 malignant tumors, six benign tumors, and one non-neoplastic lesion. Cutaneous fibrosarcoma was the most common tumor (7/16 degus). It was detected more often in females (6/7 degus) and lesions were located mainly in hind limbs. The gastrointestinal tract was frequently affected, namely with two malignant neoplasms - an intestinal lymphoma and a mesenteric mesothelioma, four benign tumors - two biliary cystadenomas, an oral squamous papilloma and a hepatocellular adenoma, and a single non-neoplastic proliferative lesion. In one animal, two organic systems were involved in neoplastic lesions.

Coccygeal chordoma in a degu: case report and review of the literature

An 8-y-old, intact female degu ( Octodon degus) was presented with a slow-growing mass on the tail tip. The mass was completely removed by partial caudectomy. Histologically, the last coccygeal vertebra was replaced by a lobulated neoplasm composed of large clear polygonal cells embedded in a myxoid alcian blue-positive matrix with highly vacuolated cytoplasm (physaliferous cells) and intracytoplasmic periodic acid-Schiff-positive granules. The neoplasm exhibited the morphologic features of a "classic" chordoma of humans, which is 1 of 3 distinct chordoma subtypes. Immunohistochemistry revealed dual expression of cytokeratin AE1/AE3 and vimentin, consistent with a diagnosis of chordoma. Chordomas are uncommon slow-growing neoplasms in humans and animals, arising from notochordal remnants. Depending on their subtype and location, they can have a high local recurrence rate and metastatic risk. Chordoma should be included in the differential diagnosis of a soft tissue mass on the tail of a degu, similar to the clinical situation in ferrets.

Structure-based stabilization of insulin as a therapeutic protein assembly via enhanced aromatic-aromatic interactions

Key contributions to protein structure and stability are provided by weakly polar interactions, which arise from asymmetric electronic distributions within amino acids and peptide bonds. Of particular interest are aromatic side chains whose directional π-systems commonly stabilize protein interiors and interfaces. Here, we consider aromatic-aromatic interactions within a model protein assembly: the dimer interface of insulin. Semi-classical simulations of aromatic-aromatic interactions at this interface suggested that substitution of residue TyrB26 by Trp would preserve native structure while enhancing dimerization (and hence hexamer stability). The crystal structure of a [TrpB26]insulin analog (determined as a T3Rf3 zinc hexamer at a resolution of 2.25 Å) was observed to be essentially identical to that of WT insulin. Remarkably and yet in general accordance with theoretical expectations, spectroscopic studies demonstrated a 150-fold increase in the in vitro lifetime of the variant hexamer, a critical pharmacokinetic parameter influencing design of long-acting formulations. Functional studies in diabetic rats indeed revealed prolonged action following subcutaneous injection. The potency of the TrpB26-modified analog was equal to or greater than an unmodified control. Thus, exploiting a general quantum-chemical feature of protein structure and stability, our results exemplify a mechanism-based approach to the optimization of a therapeutic protein assembly.

Evidence-Based Advances in Rodent Medicine

The number of exotic companion pet rodents seen in veterinary practices is growing very rapidly. According to the American Veterinary Medical Association's surveys, more than 2,093,000 pet rodents were kept in US households in 2007 and in 2012 it was more than 2,349,000 animals. This article summarizes the most important evidence-based knowledge in exotic pet rodents (diagnostics of the hyperadrenocorticism in guinea pigs, pituitary tumors in rats, urolithiasis in guinea pigs, use of itopride as prokinetics, use of deslorelin acetate in rodents, cause of dental disease, and prevention of mammary gland tumors in rats).

OBSTETRICAL AND POSTPARTUM COMPLICATIONS IN LESSER MADAGASCAR HEDGEHOG TENRECS (ECHINOPS TELFAIRI): FOUR CASES

Currently, little is known about diseases and health concerns in tenrecs, family Tenrecidae. During the past 10 yr of breeding lesser Madagascar hedgehog tenrecs ( Echinops telfairi ) at a single zoological institution, a diverse range of obstetric and postpartum complications have been observed: pyometra, metritis, retained fetal membranes, retained fetus, perinatal mortality, and maternal neglect with subsequent successful hand-rearing of neonates. Treatment of these problems is complicated in tenrecs because of their small size and secretive behavior. Some of the cases reported in this article had successful resolution by ovariohysterectomy or cesarean section. The four cases described in this report overall help to disseminate options and outcomes for the diagnosis, treatment, and management of obstetric and postpartum complications in this small, secretive, nondomestic species.

ExNOTic: Should We Be Keeping Exotic Pets?

There has been a recent trend towards keeping non-traditional companion animals, also known as exotic pets. These pets include parrots, reptiles, amphibians and rabbits, as well as small species of rodent such as degus and guinea pigs. Many of these exotic pet species are not domesticated, and often have special requirements in captivity, which many owners do not have the facilities or knowledge to provide. Keeping animals in settings to which they are poorly adapted is a threat to their welfare. Additionally, owner satisfaction with the animal may be poor due to a misalignment of expectations, which further impacts on welfare, as it may lead to repeated rehoming or neglect. We investigate a range of commonly kept exotic species in terms of their suitability as companion animals from the point of view of animal welfare and owner satisfaction, and make recommendations on the suitability of various species as pets.

Reproductive Medicine in Guinea Pigs, Chinchillas and Degus

Guinea pigs, chinchillas, and degus are hystricomorph rodents originating from South America. They are commonly presented as exotic pets in veterinary practice. Reviewing the anatomy and physiology of their reproductive tract helps to offer better client education about preventive medicine and helps to act faster in emergency situations. Choosing the right anesthetic protocol helps to prevent complications. This article should aid as a guideline on the most common reproductive problems of these 3 species and help in making decisions regarding the best treatment options.

Rodent Oncology: Diseases, Diagnostics, and Therapeutics

Cancer incidence in rodent species varies dramatically from a common occurrence in mice and rats to just a limited number of documented cases in chinchillas and degus. This article summarizes common tumors, both benign and malignant, that have been reported to occur in rodents. Outlined are clinical signs, diagnostics, and treatments that have been described for rodents presenting with specific neoplasms.

Anatomy and Disorders of the Oral Cavity of Chinchillas and Degus

Dental disease is among the most common causes for chinchillas and degus to present to veterinarians. Most animals with dental disease present with weight loss, reduced food intake/anorexia, and drooling. Degus commonly present with dyspnea. Dental disease has been primarily referred to as elongation and malocclusion of the cheek teeth. Periodontal disease, caries, and tooth resorption are common diseases in chinchillas, but are missed frequently during routine intraoral examination, even performed under general anesthesia. A diagnostic evaluation, including endoscopy-guided intraoral examination and diagnostic imaging of the skull, is necessary to detect oral disorders and to perform the appropriate therapy.

Temporal variation in Trypanosoma cruzi lineages from the native rodent Octodon degus in semiarid Chile

Chagas disease is a zoonosis caused by the protozoan parasite Trypanosoma cruzi and transmitted by triatomine insects to several mammalian species acting as reservoir hosts. In the present study, we assess T. cruzi-prevalence and DTU composition of the endemic rodent Octodon degus from a hyper-endemic area of Chagas disease in Chile. Parasite detection is performed by PCR assays on blood samples of individuals captured in the austral summers of 2010-2013. The infection level in rodents differed in the summers of these four years between 18% and 70%. Overall, infected O. degus showed similar T. cruzi-DTU composition (TcI, TcII, TcV and TcVI lineages) among years, corresponding to single and mixed infection, but the relative importance of each DTU changed among years. In 2013, we detected that only three out of the four T. cruzi-DTU found in O. degus were present in the endemic triatomine Mepria spinolai. We suggest that O. degus, an abundant long-lived rodent, is an important native reservoir of T. cruzi in the wild transmission cycle of Chagas disease and it is able to maintain all the T. cruzi-DTUs described in semiarid Chile.

Behavioral dermatopathies in small mammals

Several skin conditions seen in small mammals are thought to have a behavioral cause but their epidemiology and pathogenesis are poorly understood. A significant amount of research exists on barbering in mice that suggests it is an impulse control disorder and may represent a good animal model for trichotillomania in humans. Stress seems to play a complex role in the development and maintenance of some behavioral dermatopathies, but genetics and experiences, especially during development, also likely play a role. Pain or discomfort may underlie the development of many of these problems.

Common dental disorders of the degu (Octodon degus)

Dental disease is prevalent in the captive degu (Octodon degus), yet little has been documented on the variety of disorders in this species. In this internet-based study, dental cases presented over a 7-year period were collated, analyzed, and grouped. Of the 137 total cases, the most common dental disorder of the degu was found to be molar malocclusion (42.3 %). Other disorders documented included enamel decoloration (13.1%), molar elodontoma (8.0%), enamel hypoplasia (6.6%), incisor tooth fracture (6.6%), incisor malocclusion (3.6%), oral abscess (2.2%), and impacted molar teeth (0.7%). Details of each condition, pathogenesis, and clinical signs are described. Age was found not to be a significant predictor of dental disease in the degu.

Effect of high phosphorus diet on tooth microstructure of rodent incisors

Enamel hypoplasia and disruption of dentinogenesis are the most common abnormalities of development and mineralization of human teeth. Several reports are available in the literature on the influence of dietary calcium on the formation of human and rodent tooth; however, the information about the influence of dietary phosphorus on the tooth formation is scarce. The aim of the present investigation was to examine the chronic effect of high phosphorus diet and improper dietary calcium to phosphorus ratio on the mandibular incisor microstructure in a hystricomorph rodent--Octodon degu--using macroscopic observation, histopathological examination, transmission and scanning electron microscopy. The present study shows that enamel and dentin development is disturbed under high phosphorus diet and improper calcium to phosphorus ratio. Disturbed mineral metabolism resulted in enamel depigmentation, enamel hypoplasia, enamel pitting and altered dentin morphology. The results suggest that more attention should be focused on dietary phosphorus content when facing altered tooth structure in young patients with deciduous or permanent dentition. Furthermore, we showed that degus can be used as an experimental animal model for the study of the developmental teeth disturbances.