Hystricomorph Anatomy

What type of dentition do guinea pigs have?

Monophyodont, heterodont

What is the dental formula for guinea pigs?

I 1/1 C0/0 PM 1/1 M 3/3

How fast do guinea pig incisors grow per year?

55-65 mm

What color are chinchilla incisors?

Yellow (due to iron)

What is unique about the occlusal surface of degu cheek teeth?

Figure of 8 appearance

What type of stomach do hystricomorph rodents have?

Simple, entirely glandular

What type of digestive system do hystricomorph rodents have?

Hindgut fermenters

What is unique about guinea pig retinal vasculature?

Paurangiotic (sparsely vascularized)

What is characteristic of chinchilla eyes?

Large globe within a shallow orbit

What is a common eye problem in degus?

Rapid onset of cataracts

What is the shape of hystricomorph rodent nares?

S-shaped, longitudinal

What is the unique feature of the guinea pig upper lip?

Divided into 2 halves (philtrum)

What gland is prominent in male guinea pigs?

Grease gland

How long can chinchilla vibrissae be?

1/3 of total body length

What is "fur slip" in chinchillas?

Defense mechanism where fur detaches easily

How many digits do guinea pigs have on their manus?

4

How many digits do chinchillas have on their manus and pes?

4 on both

What is unique about the pelvis of female guinea pigs?

Joined by fibrocartilaginous suture line

What is the primary locomotion method for chinchillas?

Hopping

How high can chinchillas jump?

Over 6 feet

What is the typical respiratory rate for guinea pigs?

40-100 breaths per minute

How many lobes does the right lung have in hystricomorph rodents?

4 (cranial, middle, caudal, accessory)

What type of uterus do hystricomorph rodents have?

Bicornuate

Where are guinea pig testes typically located?

Prescrotal sac, inguinal, or abdominal

How many pairs of mammary glands do chinchillas have?

3 (2 lateral thoracic, 1 inguinal)

What is the average litter size for degus?

5-6 pups

What type of uroliths are common in older guinea pigs?

Calcium carbonate

What is the vertebral formula for guinea pigs?

C7, T13-14, L6, S2-3, Cd4-6

How many ribs do guinea pigs typically have?

13-14

What is unique about the guinea pig skull shape compared to chinchillas?

Less domed

How many digits do guinea pigs have on their pes?

3

What is the typical heart rate range for guinea pigs?

230-380 beats per minute

What is the average gestation period for guinea pigs?

59-72 days

What is unique about guinea pig pups at birth?

Born fully furred with eyes open

How many pairs of mammary glands do guinea pigs have?

2 (inguinal)

What is the average lifespan of a pet guinea pig?

4-8 years

What is the typical body temperature range for chinchillas?

36.1-37.8°C (97-100°F)

How often do chinchillas typically urinate?

Every 30-60 minutes

What is unique about chinchilla fur density?

20,000-25,000 hairs per square cm

What is the average gestation period for chinchillas?

111 days

What is the typical lifespan of a pet chinchilla?

10-20 years

What is the average body weight of an adult degu?

170-300 grams

What is unique about degu social behavior?

Highly social, live in family groups

What is the typical gestation period for degus?

87-93 days

What is the average lifespan of a pet degu?

5-9 years

What type of diet are hystricomorph rodents adapted for?

High-fiber, low-fat

What is a common health issue in all three species related to their teeth?

Dental malocclusion