Introduction

Chinchillas are long-lived hystricomorphic rodents, which have been domesticated just a century ago. Chinchillas are used as animal models in otological research and are becoming increasingly popular as companion animals. Chinchillas are adapted to a dry and cold climate, and in captivity relative humidity should be less than 60%, with less than 50% being ideal. Environmental temperature should be less than 24°C (75°F). While chinchillas are very tolerant to cold temperatures, high temperatures are not tolerated, and heat stroke may occur if the environmental temperature is higher than 27°C (80°F).

Chinchillas are social animals and are ideally kept in groups. Large cages with multiple levels are preferred (e.g., ferret cages) and single-level rabbit or guinea pig cages are not appropriate. A hiding box or other hiding structures should be provided, and if several animals are housed together, sufficient hiding space should be provided. A dust (sand) bath should be provided for short periods of time on a regular basis (at least once weekly). Commercial chinchilla sand should be used. Regular dust bathing is important, in order to allow chinchillas to maintain a healthy coat.¹

Chinchillas are obligate herbivores and are adapted to a natural diet low in water. Therefore, chinchillas should not receive fresh produce in significant amounts, in order to prevent GI disturbances. Chinchillas should be fed a diet consisting of high-quality grass hay and commercial chinchilla pellets. As treats, dehydrated vegetables (e.g., carrots) and other commercial herbivore rodent treats are suitable. Raisins and other food items high in sugar and phosphorus should not be fed in order to reduce the risk of development of dental disease. Fresh water should be provided in a bowl or bottle.¹

Chinchillas can be handled and restrained like most other exotic companion mammals, but care should be taken to avoid “fur slip,” which will occur if chinchillas are grasped by their fur.^1,2

Diagnostic Techniques

The diagnostic techniques used in chinchillas are the same as in other species; however, some diagnostic tests are fairly unique to chinchillas or have high diagnostic value. For blood collection the author prefers insulin syringes with 27–28-gauge needles in order to maximize the chance to obtain a diagnostic blood sample. The preferred venipuncture sites are the jugular veins, which can usually not be visualized, except in cachexic animals. Jugular venipuncture can be performed safely without anesthesia or sedation and usually provides the largest blood samples. The lateral saphenous vein may provide a blood sample up to 0.2 milliliters, but often only insufficient blood samples can be collected. Other venipuncture sites include the femoral vein and ventral tail vein.

Urinalysis is another valuable diagnostic test, which is currently underutilized in chinchillas. The normal urine coloration can vary considerably. The urine pH should be ≥8.5; proteinuria is normal in chinchillas and the most common urinary crystals are amorphous, while calcium carbonate crystals are not typical.² Urinalysis is also helpful to detect ketonuria in anorexic chinchillas and can be used to monitor response to treatment in these animals.

Diagnostic imaging (radiography, computed tomography and ultrasonography) may require sedation or anesthesia, depending on the imaging modality and individual animal.

Several anesthetic protocols have recently been evaluated in chinchillas.^3-5 Isoflurane anesthesia has the fewest post-anesthetic effects on food intake and fecal output. Dexmedetomidine-ketamine (DM, 0.015 mg/kg + 4 mg/kg IM/SC) anesthesia has comparable cardiovascular effects to isoflurane anesthesia and is considered safe and reliable. The DM protocol is used routinely by the author for a variety of procedures, including dental procedures.

Common Disorders

Ketoacidosis and hepatic lipidosis are very common in chinchillas and occur secondary to any disease condition which results in a negative energy balance, usually due to anorexia. Urine analysis is a simple and noninvasive diagnostic tool to diagnose ketoacidosis and monitor response to treatment. Routine plasma biochemistry will not aid in the diagnosis of ketoacidosis. Treatment should focus on the primary underlying cause, which led to anorexia, while providing nutritional support and fluid therapy.¹

Gastrointestinal disorders commonly diagnosed in chinchillas include constipation and tympany, while diarrhea is less common. Causes for constipation are insufficient food intake secondary to other underlying disorders, enteritis and metabolic disorders. Tympany occurs secondary to dysbacteriosis or hypomotility of the GI tract. Less commonly, rectal tissue prolapse or intestinal intussusception can occur. Soft feces or diarrhea are most common in younger animals. Common underlying causes include sudden diet changes, inappropriate amounts of fresh vegetables or fruits, endoparasites, or bacterial overgrowth due to inappropriate oral antibiotic use.

Dental disorders, including cheek teeth elongation, periodontal disease, tooth resorption and caries are common in chinchillas.^6,7 Periodontal disease and resorptive lesions are more common in middle-aged or older animals. The incisor and cheek teeth of chinchillas grow life-long (elodont), have no anatomic root (aradicular) and have a large crown (hypsodont). The labial aspects of the incisor teeth are physiologically orange in color. Four cheek teeth, which are morphologically identical, are present in each dental arcade. The occlusal surface is 0 degrees, and the clinical crown is very short. Excessive salivation (slobbers) is characteristic for chinchillas with intraoral pain or dental disease. Palpation of the ventral mandibular aspects may reveal boney irregularities, which occur secondary to apical cheek tooth elongation. Periodontal disease, tooth resorption and caries are very common in chinchillas and can be easily missed.

Otitis externa is uncommon in chinchillas and if present usually developed secondary to otitis media and perforation of the tympanic membrane. Therefore, diagnostic imaging of the skull should be performed in all chinchillas diagnosed with otitis externa. Otitis media is usually bacterial in origin, and Pseudomonas aeruginosa is commonly isolated. Sterile sampling of the middle ear for cytology and bacterial cultures can be performed by a percutaneous technique developed for chinchillas. The bulla is accessed in sterile fashion through its dorsal wall. This technique is performed under general anesthesia and is well tolerated.⁶

Ocular disorders are common in chinchillas. Epiphora (wet eye), conjunctivitis and corneal trauma and keratitis are commonly diagnosed. The large and exposed cornea and the only rudimentarily developed third eyelids may predispose chinchillas to corneal trauma. Pseudomonas aeruginosa is the most common isolate from chinchillas with conjunctivitis.⁸ Therefore, empiric topical antibiotic treatment, pending bacterial culture and sensitivity results, should include gentamicin- or polymyxin B-containing ophthalmic formulations.

Female reproductive tract diseases are not common in pet chinchillas. Endometritis and pyometra are the most common disorders. In breeding females, fetal retention and mummification may be seen. Neoplasia of the reproductive tract in chinchillas is uncommon.

Male reproductive tract diseases are limited to the penis and prepuce. Fur rings, balanoposthitis, preputial abscesses, paraphimosis, and phimosis are diagnosed.⁹

Urolithiasis in chinchillas is uncommon and affects predominately males. In all reported cases the calculi were composed predominately of calcium carbonate.¹⁰ Hematuria is the most common clinical sign and a single or several calculi can be found in the bladder and/or urethra.¹⁰ Urethral calculi carry a worse prognosis compared to cystic calculi. The rate of recurrence of urolithiasis in chinchillas following surgery has been reported to be 50%.¹⁰

Cardiac disease is uncommon in chinchillas, while the presence of innocent (syn. physiologic) heart murmur is somewhat common. Echocardiography is recommended for evaluation of chinchillas with heart murmurs grade III/VI or higher or in animals with clinical signs likely associated with cardiac disease.¹¹ Vertebral heart size (VHS) reference intervals using radiographs or computed tomorgraphy have been published in chinchillas. The radiographic VHS reference interval in chinchillas is 7.5–10.2.¹²

References

1.  Mans C, Donnelly TM. Disease problems of chinchillas In: Quesenberry KE,Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. St. Louis, MO: Elsevier Saunders; 2012:311–325.

2.  Doss GA, Mans C, Houseright RA, et al. Urinalysis in chinchillas (Chinchilla lanigera). J Am Vet Med Assoc. 2016;248:901–907.

3.  Fox L, Snyder LB, Mans C. Comparison of dexmedetomidine-ketamine with isoflurane for anesthesia of chinchillas (Chinchilla lanigera). J Am Assoc Lab Anim Sci. 2016;55:312–316.

4.  Parkinson L, Mans C. Anesthetic and postanesthetic effects of alfaxalone-butorphanol compared with dexmedetomidine-ketamine in chinchillas (Chinchilla lanigera). J Am Assoc Lab Anim Sci. 2017;56:290–295.

5.  Doss GA, Mans C, Stepien RL. Echocardiographic effects of dexmedetomidine-ketamine in chinchillas (Chinchilla lanigera). Lab Anim. 2017;51:89–92.

6.  Mans C, Donnelly TM. Update on diseases of chinchillas. Vet Clin North Am Exot Anim Pract. 2013;16:383–406.

7.  Mans C, Jekl V. Anatomy and disorders of the oral cavity of chinchillas and degus. Vet Clin North Am Exot Anim Pract. 2016;19:843–869.

8.  Ozawa S, Mans C, Szabo Z, et al. Epidemiology of bacterial conjunctivitis in chinchillas (Chinchilla lanigera): 49 cases (2005 to 2015). J Small Anim Pract. 2017;58:238–245.

9.  Martel-Arquette A, Mans C. Management of phimosis and balanoposthitis in a pet chinchilla (Chinchilla lanigera). J Exot Pet Med. 2016;25:60–64.

10.  Martel-Arquette A, Mans C. Urolithiasis in chinchillas: 15 cases (2007 to 2011). J Small Anim Pract. 2016;57:260–264.

11.  Pignon C, Sanchez-Migallon Guzman D, et al. Evaluation of heart murmurs in chinchillas (Chinchilla lanigera): 59 cases (1996–2009). J Am Vet Med Assoc. 2012;241:1344–1347.

12.  Doss G, Mans C, Hoey S, et al. Vertebral heart size in chinchillas (Chinchilla lanigera) using radiography and computed tomography. J Small Anim Pract. 2017;58:714–719.