ZOOLOGY

Classification

 Class: Mammals

 Order: Rodents

 Sub-order: Hystrichognathes (Wilson et Reeder) or Caviomorphes or Hystrichomorphes

 Family: Chinchillidae

 Gender: Chinchilla

 Species: laniger x brevicauda

 Common noun: chinchilla

There are two chinchilla species in the wild. Chinchilla laniger inhabits the Andes Mountains of Chile at elevations between 3000 and 4000 meters high. They are practically extinct but a colony has settled in Tajikistan. The other wild species Chinchilla brevicauda inhabits the limits Argentina- Chile-Peru.

The commercialised and domesticated species corresponds to the crossbreeding of C. laniger X C. brevicauda.

Biotope: rocky slopes in the Andes Mountains, sparse and poor vegetation.

Historical account : bred in captivity since 1923 for its fur in the United States and then in Europe after the Second World War.

Breeds and varieties

 Standard colour: grey with a lighter ventral colour

 Mutations with most black: black velvet, charcoal, ebony

 Mutations with most white: Wilson white (silver or mosaic) , starlit, albinos.

 Mutations with most beige: brown tower, champagne, almond blossom, afro-violet, pastel, beige velvet.

 Mutations with most blue: Sapphire, Sapphire velvet

 NB: the Velvet and Wilson White animals have got a lethal gene.

Juridical status

 The genus Chinchilla in the wild belongs to the annex I (A) in the Washington Convention.

 C. laniger X C. brevicauda is considered as a domestic species since 1992 under the French Rules. Only the animals born in captivity from parents born in captivity as well can be sold.

BIOLOGICAL PARTICULARITIES

Morphological And Anatomic Features

 Adult body weight:

 Male: 400-500 grams

 Female: 450-600 grams (females are larger than males)

 Body length: 25-30 cm

 Tail length: 7-15 cm

 Corporal surface: 550 to 700 cm²

 Dental formula: 20 teeth, hypsodonte incisors (continuous growth, growth 6 cm per year) , PM and M are hypsodonte as well.

 5 fingers at the front legs, 4 at the hind legs.

 Vertebral formula: 7C 13 T 6L 4S 12 Co that is 42 vertebras

Biologic data

 Behaviour: crepuscular and nocturnal activity. Chinchillas can easily adapt to their owners' diurnal life. Excellent climber.

 Social life: colonies with 10 to 100 animals, using acoustic signals against predators attacks.

 Natural hibernation: none

 Food consumption: 30-40 grams per day

 Water consumption: 10-20 mL per day

 Respiratory rate: 45-65 /min

 Heart rate: 150 / min

 Total blood volume: 20-32 mL

 Life span: 10 years, sometimes up to 20 years.

 Body temperature: 38-39 °C

PHYSIOLOGICAL PARTICULARITIES

Physiology of reproduction

 Breeding onset

 Male: 9 months

 Female: 4-5 months

 Main breeding season: November to May , anoestrus in Summer and Autumn during 5 months

 Cycle length: 30-50 days, polyestrus

 Estrus length: 31 days average

 Spontaneous ovulation

 Gestation period: 110-120 days (average 112 days)

 At birth: open eyes, with teeth

 Weight at birth: 40-60 g

 Litter size: 1-3

 Number of gestations per year: 2

 Weaning age: 6-8 weeks, the parents and young must be separated

 Teat number: 3

 Post-partum estrus: fertile (12 hours after parturition).

Haematology

 Erythrocytes: 6-8 x 10⁶/mm³

 Hémoglobin: 8-15 g/dl

 Hématocrit: 27-54 % (average 38)

 Leucocytes: 6-15 x 10³/mm³

 Neutrophils: 40-55 %

 Eosinophiles: 0-9 %

 Basophiles: 0-11 %

 Lymphocytes: 45-60 %

 Monocytes: 0-6 %

 Blood platelets: 450-740 x 10³/mm³

Biochemistry

 Urea: 0,1-0,25 g/L

 Proteins: 38-56 g/L

 Glucose: 0,6-1,2 g/L

 ALAT: 10-35 UI

 Bilirubin: 6-12,8 mg/L

 Cholesterol: 0,4-1 g/L

Urine norms

 Colour: yellow to amber

 Turbidity: trouble

 PH: 8,5

 Proteins: traces

 Glucose, nitrates, cetons, bilirubin, sang: negative

 Urobilinogen: 1-10 mg/l

 Density: 1,045

HUSBANDRY

Feeding

 Strictly herbivorous rodent that eats 50 to 90 grams of food a day

 Dry food: 30 grams of complete food such as pellets dosed at 18-20 % of proteins, good quality hay given ad libitum

NB: avoid fresh vegetable, food for rabbits or Guinea pigs.

Housing

 Spacious and large cage: 80x50x100 cm minimum (that is 400 cm ² on the floor) with several levels.

 Litter: a thick layer of hay, wood shavings, saw dust. Avoid cat litter which could be eaten.

 Dust bath with specific ground for their bath or for want, equal quantity of talc and thin sand. Those dust baths allow them to get rid of the excess of sebum in their skin.

 Avoid leaving the cage in a humid place or in drafts. Place a wooden nest box up on one of the sides.

 Put some large branches in the cage for exercise.

 Housing:

 Temperature: 18-20 ° C

 Lightning time: 12 hours

 Humidity: 30 to 70 %

Handling And Restraint

 Gentle manipulation to avoid being bitten

 Place a hand round the shoulders and the other hand under the croup, it can be seized as well by the tale base.

NB: avoid the end of the tail and pinching the skin (risk of shedding patches of fur or "fur slipping" due to a reflex vasoconstriction)

MAIN PATHOLOGY

Digestive diseases

Malocclusion

 To be suspected in any animal that looks hungry but will not eat; the lips and chin get wet because of excessive drooling.

 The reason is genetic (incisor or cheek teeth malocclusion) or dietary (long anorexia with lack of chewing and as a consequence lack of usury)

Gastro intestinal disorders with nutritional origin

 Pendulous abdomen: due to an excess of fresh food. The abdomen is enlarged by gastro intestinal fermentations.

 Constipation: mainly by lack of drinking, in some cases by intestinal atony in old animals or by lack of exercise. Caecal stasis.

 Enteritis: after a sudden diet change, diet too low in cellulose or too high in proteins, mouldy hay, fresh vegetables.

Bacterial enteritis

 Yersiniosis to Yersinia enterolytica. Responsible for important epizooties in French breeding in the 80's. Necropsy: generalized enterocolitis, necrose , mesenterical adenite.

 Salmonellosis to Salmonella typhimurium. Acute forms with death occurring within 24 hours , or chronic with deterioration and intermittent diarrhoea.

 Listeriosis (Listeria monocytogenes) -> zoonotic disease

 Other bacterial enteritis: Pseudomonas aeruginosa, Proteus vulgaris, Escherichia coli.

 Pseudomonas may cause sudden death, bronchopulmonary disorders, haemorrhages and abscesses.

 Iatrogenic enteritis is due to a wrong antibiotic use such as beta-lactamines that result in Clostridium development (Clostridium difficile, Clostridium perfringens) that contain toxins causing a necrosis of the intestinal epithelium. The death usually occurs within 3 to 6 days.

Parasitic enteritis

 Coccidiosis (Eimeria chinchillae): acute form with important aqueous and hemorrhagic diarrhoea. Abdominal tympanism and convulsions.

 Giardiasis (Giardia sp.): Trophozoites in small intestine, liver and caecum.

 Cryptosporidiosis

 Infestations with helminths are rare. Hymenolepis nana, larvae tapeworm infections

Prolapsed rectum

 Caused by diarrhoea , strong expulsive efforts ( constipation, parturition), any stress. It is often related to a colorectal intussusception and in some cases a volvulus of the small intestine. The prognosis is very poor and surgery is often to fail as the intestine is very thin and the animal is shocked.

Disorders due to fur swallowing

 Trichobezoars, constipation, intestinal occlusion

Respiratory Diseases

 Predisposing factors:

 Drafts, poor ventilation, wrong humidity, transports, any stress

 Etiology: Pasteurella multocida, Bordetella bronchiseptica, Klebsiella pneumoniae, Diplococcus pneumoniae, Staphylococcus sp., Streptococcus sp.

 Symptoms:

 Infection withPasteurella multocida. The acute form is mostly observed in young animals: purulent nasal discharge, tachypnea, hyperthermia, septicaemia-like evolution with congestive and hemorrhagic lesions. Otitis media and meningo encephalitis with purulent lesions. The chronic form : rhinitis and conjunctivitis, purulent otitis, cutaneous or subcutaneous abscess.

 Other bacterial affections: conjunctivitis, rhinitis, bronchopneumonia, often turns into a septicaemia, otitis media, meningitis. Necropsy: fibrino-purulent pleurisy, pericarditis.

Skin diseases

 Dermatophytosis: mostly due to Trichophyton mentagrophytes, sometimes Microsporum canis, M. gypseum.

 Alopecic lesions with scabs on the head and feet. The fur looks moth eaten.

 Fur chewing: it appears to be a vice of chewing its own fur on the flanks and behind. Stress and poor housing conditions have been incriminated, as well as absence of dust bath.

 Ectoparasites: fleas (Xenopsylla cheopis, Ctenocephalides felis), scabies to Atricholaelaps chinchillae.

Cardio vascular diseases

 Heart diseases

 Heatstroke: when the temperature rapidly reaches 30 to 35 °C.

Ocular diseases

 Conjunctivitis: mechanic irritation (from the dust bath) or lack of ventilation, infectious (Pseudomonas aeruginosa, Chlamydia spp.), deficiency in A vitamin.

 Traumatic ulcerous keratite

 Posterior cataracte

Reproduction

 Penile hair ring: a ring of twisted hair around the penis can cause a necrosis of the penis.

 Infections in females: Pseudomonas aeruginosa, Staphylococcus aureus.

 Dystocia in females that were covered when too young or if the foetal volume is excessive.

 Gestation toxaemia: post partum or during lactation

 Mortinatality by foetal anoxia, agalactia or puerperal cannibalism

Miscellaneous diseases

 Convulsive crises: deficiency in B1 vitamin, circulatory disorders

 Calcinose by hypervitaminose A

 Deficiency in E vitamin: degenerative myopathy, sterility.

ZOONOSES

 Dermatophytosis (T. mentagrophytes, M. canis, M. gypseum)

 Lymphocytic Choriomeningitis

 Listeriosis (Listeria monocytogenes) : rapid evolution (2 to 3 days). Anorexia, diarrhoea, constipation, rectal prolepsis, nervous disorders (ataxia, convulsions, hind paralysis)

 Yersiniosis (Yersinia enterolitica, Y. pseudotuberculosis)

 Tuberculosis (Mycobacterium bovis, M. avicum)

 Pasteurellosis (Pasteurella multocida) : transmitted by bite

 Toxoplasmosis

 Cryptosporidiosis

 Hymenolipis nana

REPRODUCTIVE DISEASES

Chinchilla sexing

 Sexual dimorphism is poor at the beginning and a close examination is required.

 Male have a longer anogenital distance, about 1 cm. The penis is easily exteriorised.

 Female have a urethral penis-like orifice that can be mistaken for a penis. It is close to anus and separated from it by a thin horizontal skin fold.

Main pathology

1.  Infertility

a.  Lethal genetic crossing

i.  The Velvet and Wilson White mutants are dominant heterozygote and have a lethal gene.

ii.  Two chinchillas who have the same Velvet gene cannot easily breed.

b.  Wrong housing

c.  Genital infections

i.  Pseudomonas aeruginosa and Staphylococcus aureus can cause vaginitis, endometria, metritis, sterility or in some cases foetal mummifications.

2.  Difficult covering

a.  Penile hair rings

i.  Rings of twisted hair around the penis can prevent the male from covering or cause a permanent penis prolapsus.

b.  Vaginal membrane persistence

c.  Incompatibility of the couple with aggressiveness between the partners

d.  Vaginal or uterine prolapsus after too violent covering

3.  Dystocias

a.  Etiology: too important foetal volume, female who was covered too young, too large litter size, covering at the post partum oestrus (12 hours after parturition with ovulation 30 hours later)

b.  Treatment: Ocytocine 1 U and Calcium Gluconate 40 %: 0,5 mL

i.  If that is not enough, caesarean

4.  Post partum disorders

a.  Gestation toxaemia in females that are obese before parturition or during lactation. The treatment is illusory.

b.  Mastitis

i.  Etiology: due to trauma inflected by the suckling young teeth, too early weaning, bacterial infection.

ii.  Treatment: warm compresses, antibiotherapy (chloremphenicol, quinolones)

iii.  Prevention: polishing the teeth and nails of the neonates.

5.  Neonates mortality

a.  Foetal anorexia after difficult parturition

b.  Primitive or secondary (due to mastitis) agalactia. Artificial milking every three hours with maternised milk for domestic carnivores.

c.  Puerperal cannibalism

REFERENCES

1.  Carpentier F. Contribution à l'étude du chinchilla considéré comme animal de compagnie. Thèse Doc. Vét. E.N.V. Lyon, 1994: 121 p.

2.  Harkness J.E., Wagner J.E. The biology and Medecine of rabbits and Rodents. 4th Ed. Williams x Wilkins, Media PA, 1995: 372 p.

3.  Hillyer E., Quessenberry K. Ferrets, Rabbits and Rodents. W.B. Saunders Compagny, Philadelphie, 1997: 241-289.