Chapter 9. Biology and Diseases of Chinchillas Flashcards
Chinchilla taxonomy
Order Rodentia
Suborder Hystrichognatha
Family Chinchillidae
-Related to guinea pigs and degus
Two species of chinchilla
1) Short-tailed chinchilla: Chinchilla chinchilla
2) Long-tailed chinchilla: Chinchilla lanigera (most common for biomedical research)
- Most captive chinchillas descended from 11 animals captured in early 1920s
Natural habitat of chinchillas
- Native to South America, specifically dry climate of Andean mountains of Chile, Bolivia, Peru
- Live in colonies in burrow systems
- Both species critically endangered (International Union for Conservation of Nature) - illegal hunting for fur, habitat reduction
Chinchillas uses in research
- Similarities to human hearing range, anatomical size, accessible tympanic bullae = acoustic research model since 1970s
- Otitis media, cholesteatoma, therapeutic treatment of aural disease, noise and chemical-induced hearing loss, Meniere’s disease, tinnitus, perilymphatic fistulas, cochlear implants, superior canal dehiscence, tympanic membrane perforation repair, stem cell transplants, otic drug safety testing
- Upper resp tract pathogens: Haemophilus influenzae, Moraxella catarrhalis, respiratory syncytial virus
- Hypothyroidism, repair of dural tears, pathogenic biofilm mediators of Pseudomonas aeruginosa, propagation of Taenia solium taeniasis eggs and adults
Sources of chinchillas
- NOT inbred or widely available commercially
- Moulton Chinchilla Ranch in Rochester, MN (since 1966)
- Local chinchilla fur farms and pet suppliers
Chinchilla housing
- Similar to rabbits and guinea pigs - modifications may be needed as chinchillas can squeeze through small openings
- Solid bottom caging preferred; suspended metal or plastic okay if perforations no larger than 0.5 in x 0.5 in to prevent foot and leg injuries - should also have a solid floor area
- Chinchillas good at jumping and climbing - multilevel cages provide enrichment
- Items to gnaw for dental health & items to orally manipulate
- Will perch on flat-topped structure
- Line dropping pans with absorbent material
- Dry, draft free environment
Housing space for chinchillas
- No standard floor space and height requirements
- Pet trade: 1-2 ft2 (0.1-0.2 m2) per animal and 12 in (30 cm) cage height
Bedding for chinchilla housing
Wood shavings or paper-based products
-NO wood products containing aromatic hydrocarbons (pine shavings) - may affect drug metabolism, predispose to respiratory problems
Unique housing requirement for chinchillas?
Dust Baths
- Mixtures of silver sand, Fuller’s earth, diatomaceous earth, volcanic ash
- Provide for 15 min daily, or at least several times per week
- Remove baths between uses & do not share between enclosure to prevent disease transmission (ringworm)
- Overuse - eye irritation & dry skin
- Do not give to near-term females or mothers with litters - mastitis and uterine infection
Social housing of chinchillas
-Are social; should house in same-sex pairs or groups
Temperature & humidity for chinchillas
Temp: 63-77 F (17-25 C)
Humidity: 30-60%
-Very prone to heat stress - mortality at temps exceeding 90 F (32 C), particularly if humidity also high (>60%)
-Guide to sum units of humidity and temp in F: should not exceed 150
-Can be cold adapted to temps of 32 F (0 C) or lower to stimulate production of thick fur coat
Ventilation and light cycle for chinchillas
10-15 air changes per hour
12: 12 h light:dark cycle
- May need to alter for breeding
Watering for chinchillas
- Rarely drink water
- Maintain hydration by licking dew drops and eating plants
- Captive chinchillas adapt to water bottles or automatic watering systems
Handling chinchillas
- Grasp base of tail with one hand while other hand supports the body
- Never pick up by the tail alone
- Can pick up tamer animals around the thorax while supporting the hind end
Furslip in chinchillas
A protective mechanism employed to evade predators
- A patch of hair is simultaneously released from the follicles, leaving a bare area of skin
- Rough handling
Describe the chinchilla ear.
- Like humans, cochlea has 3 turns, readily accessible for microsurgery
- Large, thin-walled tympanic bullae = easy access to middle ear
- Similar range of hearing to humans
- Freely mobile conductive apparatus = malleus & incus are attached by liagments - can move independently; other rodents (mice, gerbils, hamsters) there is bony fusion btwn malleus and tympanic ring
- Round window thinner than humans - useful for ototoxic drug studies
- Age-related hearing loss similar to humans
What is the average chinchilla lifespan?
9-18 years
What is the blood supply for the brain in chinchillas?
ONLY the vertebral-basilar artery system
NO internal carotid arteries
Do chinchillas have a right coronary artery?
No
Unique lymphoid tissue features in chinchillas
- Thymus located entirely within thorax
- Have discrete nasal-associated lymphoid tissue (NALT) similar to other rodents
Describe the chinchilla GI system.
- All teeth open-rooted, grow continuously
- Soft palate is continuous with base of tongue, contains palatal ostium - connects oropharynx to rest of pharnyx
- Large intestine 1.5x longer than small intestine
- Coprophagic - cecal pellts taken directly from anus, masticated, swallowed; typically only ingest pellets produced during daytime - higher nitrogen content than night pellets
- Unable to vomit
Urine concentrating ability of chinchillas
Relatively large renal medulla allows conservation of water; highly concentrated urine
Life cycle values for chinchillas
- Breeding onset male: 7-9 mth
- Breeding onset female: 4-5 mth
- Cycle length: 20-60 d
- Gestation: 105-120 d (avg 112)
- Postpartum estrus is fertile
- Birth weight: 30-60 g
- Litter size: 1-6 (2-3 most common)
- Weaning age: 6-8 wk
- Breeding life: up to 10 yr
Normal physiologic values for chinchillas
- Adult body weight: 400-600 g (females can be bigger than males)
- Body temp: 37-38 C (98.6-100.4 F)
- Pulse: 200-350 bpm
- Resp: 45-80/min
- Life span: 9-18 yr
- Food consumption: 30-40 g/day; 5.5g/100g/day
- Water consumption: 10-20 ml/day; 8-9ml/100g/day
Chinchilla chromosome number
Diploid number - 64
Chinchilla diet
- Monogastric hind gut fermenters
- High-fiber, low-energy diet with 16-20% protein, 2.5-5.5% fat, 15-23% fiber
- Low protein diet may result in unthriftiness and dry, weak fur
- Pelleted ration; supplement with free-choice grass hay or other high fiber substance
How do chinchillas prefer to eat?
Sit upright on haunches and hold food in forepaws when eating
-Commercial chinchilla pellets longer than G pig pellets to facilitate this behavior
Appropriate treats for chinchillas
- Small amounts of washed, dark green leafy veggies
- Avoid high starch or sugar = GI upset
- Avoid mixed rations = chinchillas will pick out only what they like
How should food be offered to chinchillas?
Suspended food hopper or J-feeder will prevent waster and feed contamination
T/F: Chinchillas eat most of their feed during the dark phase
True. Chinchillas are nocturnal.
Chinchillas behavior
- Social animals - house in same sex pairs or small groups; huddling and mutual grooming occur
- Provide solid running wheels to minimize foot and leg injuries
- Require safe items for gnawing
- Not very vocal, but normal vocalizations include soft high-pitched grunts, angry barks, warning whistles
- Can be territorial and spray urine at an intruder
- Like guinea pigs, do not adjust readily to environmental changes
- Nocturnal, but can adapt to diurnal lifestyle in captivity
Aggression in chinchillas
- Female may be aggressive when in estrus or post-partum, esp towards males
- Intact males may fight
Sexing chinchillas
Anogenital distance
- Females have prominent urethral papilla (can confuse with penis)
- Males can retract testicles into abdomen
Estrous cycle in chinchillas
- In Northern hemisphere, seasonally polyestrus from Nov-May
- Estrous cycle lasts 20-60 days (avg 35)
- Estrus last 12-48 hr: opening of vaginal closure membrane, vaginal reddening and discharge
- Waxy vaginal plug normal at onset of estrus
- Female monogamous in wild; can use harem scheme in captivity w/ 1 M for every 4-6 F
Caging system for harem breeding in chinchillas
- Females fitted with flat metal disc around neck so they cannot leave their own cage
- Tunnel system connecting cages allows male to move freely between cages
- Interested males make a cooing, chuckling noise & both sexes rub chins on the floor
Signs of receptivity in females chinchillas
- Lordosis and lateral deviation of tail
- Following mating, female may become aggressive towards male - growling, chattering teeth, spraying urine
- Mating may occur several times during night; loss of some fur from female normal during this time
- Ejaculatory plug present for several hours
Gestation in chinchillas
- 105-120 days
- At about 60 days, mammary tissue enlarges
- Female weight gain of 25-30g/mth initially, with more rapid increase in last month
Parturition in chinchillas
- Females near parturition become inactive and anorectic; perineal area, mouth and nose become wet with amniotic fluid to signal start of parturition
- Parturition generally at night or early morning
- Labor lasts 1-2 hours or less; generally all kits born within a 4 hr period
- Female will use teeth to pull kits from birth canal
- Dystocia uncommon, but consider C-section if more than 4 hr of unproductive labor
Postpartum estrus in chinchillas
~12 hr after parturition and lasts for 2 days after which the vaginal closure membrane reforms
Chinchillas kits
- Avg litter size of 2-3
- Dams do not normally build a nest but nest boxes may reduce mortality
- Birth weight: 30-60 g; kits <25 g unlikely to survive
- Newborns fully furred with complete set of teeth and able to walk within 1 hr
- Eyes open within 24 hr of birth
- Weaning between 6-8 weeks
- Begin to eat small amounts of solid food in first week of life
- Orphans can be fostered onto female with a small litter of approximate small age, or with a litter ready to be weaned - introduce orphans a few hrs after older pups removed
Assisted breeding techniquesin chinchillas
Electroejaculation, AI, cryopreservation of sperm
Infectious agents that chinchillas are susceptible to for model purposes
Respiratory syncytial virus Adenovirus Influenza A Vesicular stomatitis virus Moraxella catarrhalis Haemophilus influenzae Streptococcus pneumoniae Pseudomonas aeruginosa Chlaymydia trachomatis
