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Care, husbandry and of the African giant (Cricetomys gambianus)

R G Coopera

nia, to detect landmines and sniff out tu- ABSTRACT berculosis. Apopo was registered under The African giant rat lives up to 14 years in captivity, reaching maximum body weights of the Belgian law as a non-commercial com- approximately 2.80 kg in bucks and 1.39 kg in does. In Britain, the African giant rat is increas- pany, and started its 1st experiments in ingly becoming a popular exotic . A survey was conducted on 41 licensed pet shops in early 1998. The giant rat is not listed on the UK. The range of ages of giant rat presented for sale, single price per rat, paired prices (buck and doe) and transport costs were 4–12 weeks, £320–£370, £352.50–400.00 including CITES as rare or endangered. VAT,and £10–37.50, respectively. Ivermectin injected at 200-400 µg/kg subcutaneously once In Britain, the African giant rat is in- a week for 3 weeks will eliminate ectoparasites (and many endoparasites). Nematode creasingly becoming a popular exotic pet can also be treated with fenbendazole or piperazine. Bladder threadworms can supplied legitimately through reputable be treated with fenbendazole, protozoa with metronidazole (not in gravid does) and pet dealers. Pet shop suppliers must be cestodes with praziquantel. Treatment of with doxycycline administered licensed through the local authority (LA). 4.29–5.36 mg once a week is useful prophylactically, although for insurance of effectiveness, Current stipulations for housing small 10 mg/kg for 5 days is recommended. An identical dosage is recommended for the treat- in the UK (formerly Pet ment of rickettsia. African trypanosomosis , following diagnosis of parasites in a Act, 1951 and currently ETS no. 123, 2007) blood smear, can be treated with a variety of antiprotozoal like diminazene specify that for a single rat, 500 cm2 are diaceturate at 3.5 mg/kg for 5 days. Leishmaniasis is treated at the same dose. required in a cage with a height of 20 cm. Staphylococcosis is treated with amoxycillian trihydrate at 5 mg/kg 3 times a day for 7 days. Each additional rat requires 125 cm2 of Helminthosis is treated with broad-spectrum deworming solution. Coccidiosis is treated space to be added. Obviously this should with cotrimoxazole at 100 mg/kg daily for 3 days. Non-steroidal anti-inflammatories are ad- be trebled when housing young African ministered to combat secondary bacterial infection after viral invasion. giant . Given the housing of African Key words: African giant rat, care, Cricetomys gambianus, , husbandry. giant rats in countries with colder cli- Cooper R G Care, husbandry and diseases of the African giant rat (Cricetomys gambianus). mates, adequate measures must be taken Journal of the South African Veterinary Association (2008) 79(2): 62–66 (En.). Division of Physiol- to ensure that correct procedures are fol- ogy, Birmingham University, 704 Baker Building, Franchise Street, Perry Barr, lowed to ensure the proper care and Birmingham B42 2SU, UK. keeping of this rat. The aim of this article is to familiarise the small- veterinary practitioner with the biology, care, hus- INTRODUCTION They are easy to tame, frequently eating bandry and diseases of this of rat. The African giant rat or the Gambian out of a trainer’s hand shortly after cap- This is not an extension of popular , Cricetomys gambianus (Water- ture9. They are being trained effectively articles written by enthusiasts, but a more house 1840) (order Rodentia; family by the Belgian firm Apopo at Sokoine Uni- conjugant analysis of the factors affecting ) (Fig. 1), is the world’s largest versity of Agriculture in Morogoro, Tanza- successful and keeping of nocturnal rat and is native to tropical Africa, where it is recorded from 29 coun- tries, many thriving in urban settings1,9,10. Their ecological range extends from Sene- gal and the Gambia east across West Africa and the Congo Basin to the Indian ocean coast of East Africa13,16,32, where it is mainly used as a meat source25. It is agri- culturally important and is biologically interesting in terms of its matriarchial social structure and its value to , for example when trained to detect land- mines. Unfortunately, it is still widely persecuted by slash-and-burn and other destructive practices11. These animals live up to 14 years in captivity, reaching maxi- mum body weights of approximately 2.80 kg in bucks and 1.39 kg in does12. aDivision of , Birmingham City University, 704 Baker Building, Franchise Street, Perry Barr, Birming- ham B42 2SU, UK. E-mail: [email protected] Fig. 1: An adult female African giant rat (Cricetomys gambianus)agedc. 18 months Received: October 2007. Accepted: April 2008. (reproduced with permission from A Bickers, www.pouchedrats.co.uk).

62 0038-2809 Tydskr.S.Afr.vet.Ver. (2008) 79(2): 62–66 a wild . Given that the source of Table 1: Notable differences between the black and giant rat. this exotic animal is from breeders in Africa, it is important that wildlife officials Name Giant Rat and veterinarians on that continent understand and appreciate the manifes- Species rattus Cricetomys gambianus tations of giant rat handling and export. Swimming Poor Moderate Literature dealing specifically with the Agility Excellent climber Excellent climber giant rat is largely lacking and therefore Length body (cm) 15–20 90–100 reasonable assumptions have been made Length (cm) 20 85 concerning the husbandry and treatment Fur Black-light brown with paler Light brown with lighter brown underside under parts, and a white tipped of the giant rat based on information tail up to 15 cm in length. available on Rattus rattus and the Sprague- Habits Nocturnal and omnivorous Nocturnal and omnivorous Dawley rat. It is hoped that this paper Nesting Arboreal Subterranean will provide the impetus to conduct Breeding 3–6 litters p.a., up to 10 pups 5 litters p.a., up to 5 pups more scientific studies of this species in Lifespan 2–3 yr 7–14 yr captivity.

MATERIALS AND METHODS the attenuation of stress in the animal Giant rats sleep during the day and it is cannot be divorced. This includes allow- preferable not to disturb them. Exposing Literature search ing them to take some solid food from them to light sources at night should be Literature was gathered from a number one’s hand, rather than presenting it in a avoided. Like the domesticated rat, they of web sites specifying imports and diseases dish. They tame very easily and are highly have an acute of hearing, and should of the African giant rat, notably the intelligent, readily participating in a not be exposed to irritating noises exceed- Department for Environment, Food and variety of activities. The rat should be ing 85 decibels4. Rural Affairs (DEFRA), UK, and the gently supported by one hand under its United Nations Environment Program- belly and the other at the base of its tail. It Breeding, lactation and weaning me (UNEP). Articles specific to the African should never be lifted by its tail or head. The gestation period for a pregnant doe giant rat were sought on PubMed, is 31 ± 4 days. The litter size is 1–5 pups Agricola and Medline web sites. Housing and bedding with a sex ratio of 1:1. Sexual maturity as As the rat is nocturnal, the cage must described at the attainment of the 1st Questionnaire survey of pet shop have a dark compartment in which it can breeding assignment is 23 weeks ± owners in the UK take refuge. It is essential that the cage is 12 days. The weight of a pup at birth var- A survey of 41 licensed pet shops in the maintained as dark and cool as possible. ies from 21 to 36 g. Does can produce up to UK that either specialised in selling rats or Giant rats like torn-up newspapers as 5 litters per year, weaning occurring be- sold a variety of mammals was conducted. bedding, and use it together with straw or tween days 26 and 35. The mortality rate Questions were devised and distributed pine needles to construct a nest into pre- and post-weaning is 2 %. There are by e-mail or letter to determine the inci- which they . Given the high no documented scientific data regarding dence of rats sold according to age, if the absorptive capacity of newspaper, the the length of the oestrus cycle, although rats are sold singly or in pairs, the price bedding should be replaced regularly due one might assume that it is comparable per rat and transport costs. to its tendency to soak up urine. Sprague- with other rat species (4–5 days). Addi- Dawley and Wistar rats kept on aspen tionally, no documented evidence exists RESULTS have greater sneezing rates and lung to describe the appearance of vaginal No peer-reviewed literature or articles than those on paper bedding, plugs of coagulated semen in the giant rat were available on some aspects of raising concerns about aspen, which is as an indication of mating. Presumably keeping the African giant rat. Suggestions relatively inert compared with other wood the giant rat has post-partum oestrus as were therefore made based on the experi- beddings, but nevertheless more harmful seen in Rattus rattus, but unfortunately ence and expertise of the author and some than paper7. Cage-cleaning rates have there are no specific studies detailing this. personally published information of a little effect on rats’ sociability7. Indeed, the Cooper suggested a matriarchal interac- popular nature. A comparison between introduction of fresh bedding encourages tion in rat colonies numbering up to 35, Rattus rattus and the giant rat is given in exploratory activity and nest building commonly found in old termite mounds Table 1. by the giant rat, and is likely to have bene- or in with several bolt-holes9. ficial cardiovascular and behavioural The author observed that in the event of Handling effects. The giant rat is more hygienic the dominant female being killed, the In the wild the giant rat is commonly than the domesticated rat, as it prefers to sister rats successfully take over the care captured from a branch in a tree up which urinate and defaecate in one corner of its of the young and at least 1 will come into it has scampered to avoid . The rat is cage. However, because of the inevitabil- oestrus. Although there is no scientific evi- usually captured by placing a sack over its ity of faeces entering the drinking and dence to prove this, it is assumed that the body, and interestingly, it usually does food containers, it is recommended that sister does respond to the feeding cries of not resist. The rat is then allowed to move these be provided from elevated plat- the pups. There may be a pheromone- around in a basin or cage and readily takes forms and/or drinking bottles. Regular mediated mechanism as seen in mice, i.e. bread to eat, usually out of its captor’s disinfection of cages will maintain a the Whitten-Bruce effect. It has been sug- hands. Indeed, recently acquired giant healthy colony. gested that the sequestration of sister rats from a pet shop may be nervous, and Temperature and relative humidity re- does into adjoining chambers of the col- a good way to encourage them to get used quirements closely match those for the ony results in anoestrus in the majority. to their new owner is to hand-feed them. domesticated rat, with a range of 20–25 °C Additionally, pheromones released from The association with food reception and (68–77 °F) and 50–55 %, respectively8. the bereaved buck may prevent implanta-

0038-2809 Jl S.Afr.vet.Ass. (2008) 79(2): 62–66 63 tion of fertilised ova in the sister rats, Table 2: Nutrient composition of meal dead skin and wax. Injection with 1 but still stimulate lactation. In captivity, suitable for feeding an African giant rat. release% Ivomec® (ivermectin) (Aceta however, their interaction is unusual and Pharma GmbH, Hamburg, ) at a Nutrient Percentage sometimes a buck and doe will fight. dose of 200–400 µg/kg subcutaneously Commonly it is the buck that becomes once a week for 3 weeks will eliminate Crude protein Min. 20 aggressive and bites the doe. This is ectoparasites (and many endoparasites). Carbohydrate Max. 60 unexplained and may be due to the high Studies have shown no adverse effects of Crude fibre Max. 5 sociability trait in giant rats, making them ivermectin on pregnant rats29. Topical liq- Fat Min. 5 more vulnerable to anhedonia elicited by uid applications dropped on the back of and trace elements 0.2 chronic stress in conditions of single the neck may be useful and include Xeno housing34. In some cases they will simply release450 (Genitrix Ltd., Billingshurst, not mate. If mating takes place success- bedding and floor covering should be UK), the active ingredient being iver- fully within 3 weeks, however, the doe changed at regular intervals to reduce mectin. It therefore acts as an endectocide should be isolated from the buck until cage contamination. Compared with the for the control of mites, roundworms and parturition. Pups are born naked, blind albino rat, the giant rat has less malodor- lice. Nematode infections can also be and deaf. ous urine and its habit of urinating in one treated with fenbendazole or piperazine. corner ensures less cage contamination. Bladder threadworms can be treated with Food Ammonia build-up is significantly re- fenbendazole, protozoa with metronida- Natural food habits indicate a prefer- duced if absorbent bedding is used under zole (not in gravid does) and cestodes ence for vegetable items (especially grass, solid tray inserts. It is important to avoid with praziquantel, niclosamide or grains and tubers); oil-palm nuts and wire-bottomed cages for adult rats in thiabendazole. Fenbendazole-medicated kernels; insects (especially ants, crickets, order to minimise foot injuries, abscesses chow remains an effective and practical etc.) and other invertebrates. When feed- or discomfort due to pressure experi- method to eliminate pinworm infections ing the rats commercial pig rations, enced on the feet. It is probably reason- in mice and rats18. Studies using rats that growth performance improved when the able to assume that studies of caging type were naturally infested with Syphacia protein level was raised from 10 to 13 %2. on foot lesions in other species of muris and kept in forced-air, individually At research centres, giant rats can be rat would have similar manifestations in ventilated cages showed that ivermectin successfully fed on tubers (sweet potatoes the giant rat. For instance, notable abnor- given orally at a dose of 2 mg/kg for or cassava), fruits of all varieties, stale malities of the plantar surface of the hind 3 treatments at 7- or 9-day intervals re- bread, amaranth, peanuts and rabbit foot, including ulcers or nodular swell- sulted in eradication19. Paired ivermectin pellets. ings, were common after 1 year in heavier treatments given at 7- or 9-day intervals Dog meal is a useful carbohydrate and Sprague-Dawley rats housed on wire were ineffective in eliminating parasites19. bulk feed (Table 2). Peanut butter is a flooring compared with polycarbonate Abscesses may occur more frequently favourite, and when mixed into the meal cages28. The microenvironment of poly- when cages have sharp areas and unhy- provides a stimulus for its consumption. carbonate cages housing Sprague- gienic conditions. The African giant rat Sometimes cooked chicken can be given, Dawley rats showed that contact bedding has been linked, along with 2 other but not ad libitum as there is a tendency was useful in controlling ammonia gener- imported African species, to the spread of to hoard it in bedding material. ation and that a raised floor walk insert monkey pox in the USA21, the reduced significantly the aerosolization Democratic Republic of Congo20 and Cage requirements of bedding particles that could be in- possibly the Caribbean10, although there Galvanised metal should be avoided for gested or inhaled by the rats31. have been no substantiated reports in the cages, as gnawing may result in the inges- The reduction in ammonia is important, UK. Other diseases/infections associated tion of zinc. Indeed, chronic exposure to as the fumes exacerbate respiratory with the giant rat should be noted, as they zinc has been shown to increase levels of problems, particularly from mycoplasma could potentially be transmissible to , a factor implicated in infections6. A well-ventilated room is owners, especially if they were caught, seizures33. Chronic zinc exposure in an important to blow away these fumes. It is tamed and reared from the wild. These African giant rat resulted in lethargy, vital to use uncontaminated bedding, to include: cestode infestations25, nema- withdrawal, soft, mucus-impregnated avoid exposing the rats to diseases, todes14, serovar infection26, faeces and diarrhoea, foot twitching and particularly mites and tapeworms. Over- trypanosomiasis17, rickettsia24, Leishmania icterus12. Indications of moderate zinc crowding should be avoided, with a maxi- tropica23, Potiskum virus27, Ife virus15, toxicosis following ingestion and stress- mum housing density of 3–4 adults/m2. coagulase-positive Staphylococci1, helminth associated glucosuria have been re- Cage design should ensure the sequestra- infections22 and coccidia35. Treatment of ported12. Aluminium cages should also be tion of sleeping, feeding and play quarters. leptospirosis infection involves the use of avoided, especially for young rats that It is convenient to supply water in a drink- drugs like doxycycline, penicillin, ampi- are susceptible to aluminium-induced ing spout and feed in a food bowl. A mini- cillin and amoxicillin. Doxycycline is changes in the metabolism of essential mum cage height of 1 metre and total administered orally at 2.14 mg every 12 h nutrients30. It is recommended that cheap floor area of 2 × 1.5 m2 will accommodate for 7 days. Doxycycline administered but strong wood from pallets be used and, this large species. Some owners construct 4.29–5.36 mg once a week is useful pro- if necessary, nailed double-length and arunof10×15m2 into which the rat can phylactically, although to ensure effec- strengthened with windows covered with be released for exercise and play. tiveness, 10 mg/kg for 5 days is recom- chicken wire. Some cages made of poly- mended (R. Cooper, Veterinary Clinic, propylene have been used, but they are Diseases and treatment Bulawayo, Zimbabwe, pers. comm., not always suitable, especially in climates Giant rats are naturally infested with 2008). An identical dosage is recom- with high relative humidity, as condensa- Hemimerus talpoides and may have ticks. mended for the treatment of rickettsia. tion easily forms inside them. Dried pine The former is harmless and non-trans- African trypanosomosis infection, follow- needles or grass and sawdust used as missible to other species, serving to eat ing diagnosis of parasites in a blood

64 0038-2809 Tydskr.S.Afr.vet.Ver. (2008) 79(2): 62–66 smear, can be treated with diminazene respectively. In England, Wales and Scot- 5. Björnsson M J, Velschow S, Stoltze K, diaceturate at 3.5 mg/kg for 5 days. Leish- land, there were 26, 10 and 5 respondents Havemose-Poulsen A, Schou S, Holmstrup P 2003 The influence of diet consistence, maniasis treatment is dispensed at the respectively. The county of Oxfordshire drinking water and bedding on perio- same dose. Staphylococcosis is treated had the greatest return rate of question- dontal disease in Sprague-Dawley rats. with amoxycillian trihydrate at 5 mg/kg naires (56 %). Positive respondents either Journal of Periodontal Research 38: 543– 3 times a day for 7 days. Helminthosis is sold or ordered giant rats. Some pet shops 550mm treated with deworming drugs. Cocci- acted as middlemen by ordering the rats 6. Broderson J R, Lindsey J R, Crawford J E diosis is treated with cotrimoxazole at on behalf of private breeders. Rats were 1976 The role of environmental ammonia in respiratory mycoplasmosis of rats. Ameri- 100 mg/kg daily for 3 days. Non-steroidal principally ordered from breeders in can Journal of Pathology 85: 115–130 anti-inflammatories are useful supportive Africa or in Europe. The range of ages of 7. Burn C C, Peters A, Day M J, Mason G J 2006 medications for secondary bacterial infec- giant rats presented for sale, price per sin- Long-term effects of cage-cleaning fre- tion as a consequence of viral infection. gle rat, prices per pair (buck and doe) and quency and bedding type on No evidence of periodontal disease exists transport costs were 4–12 weeks, £320– , welfare, and handleability: a cross- laboratory study. Laboratory Animals 40: in the giant rat, unlike in the Sprague- £370, £352.50–400.00 (including VAT), 353–370 Dawley rat, in which a finely milled diet, a and £10–37.50, respectively. Most shops 8. Canadian Council on Animal Care 1980 wire mesh floor and tap water, instead of were reluctant to indicate the percentage Guide to the care and use of experimental a regular diet, bedding and acidic water, of sales of giant rats for profit and confi- animals Vol. 1. Canadian Council on Animal attenuates its incidence5. dentiality reasons, although some said Care, Ottawa, Ontario that they sold 5–10 giant rats per year. 9. Cooper R G 2000 Giant rats in Zimbabwe. Rat & Gazette 6: 26 Legislation on the import of rats into 10. Cooper R G 2006 The possibility of naturali- the UK DISCUSSION sation of the African giant rat (Cricetomys Directive 2003/459/EC (Art. 2) prohibits The African giant rat is an extremely gambianus, Waterhouse, 1840) in the Carib- the import of non-domestic species of interesting and entertaining exotic pet and bean. Living World, The Journal of the Trinidad and Tobago Field Naturalists’ Club: 54–55 originating in 3rd-world countries lives for a longer time that the domestic rat. of sub-Saharan Africa (including Criceto- 11. Cooper R G 2008 Animal welfare. In: It is highly intelligent and friendly and its Cooper J E, Cooper M E Introduction to veter- mys gambianus) under Commission Deci- care is relatively easy although it does inary and comparative forensic medicine. sion of 20/06/2003 for protection against require a higher protein intake than the Blackwell Publishing, London: 81 monkey pox virus. Pet rodents can be domesticated rat. It is assisting mine- 12. Cooper R G, Erlwanger K H 2007 Hyper- imported from Europe without undergo- clearing in former war-torn countries and zincaemia in a pet African giant rat (Criceto- ing quarantine under Reg. 998/2003 Art. 7, mys gambianus, Waterhouse,1840). Journal of greatly reducing costs for the detection of the South African Veterinary Association 78: assuming there are no CITES or DWA im- diseases like . Although it has 163–165 plications. Rats should ideally be treated the potential to act as a vehicle in spread- 13. Coryndon S C, Gentry A W, Harris J M, against parasites in the country of origin. ing disease, strict quarantine and veteri- Hooijer D A, Maglio V J, Howell F C 1972 According to the Department for Envi- nary inspection of animals obtained Mammalian remains from the Isimila pre- historic site, Tanzania. Nature 237: 292 ronment, Food and Rural Affairs legally will eliminate the vast majority of (DEFRA), UK, rats can be imported under 14. Diouf M, Durette-Desset M C 2002 Two such infections. Further investigations new species of Nippostrongylinae (Nema- the Balai Directive 92/65/EEC and on bedding material, food and social toda, Trichostrongylina) parasites of Crice- Passport from EU countries to the UK. interaction in captivity of this species are tomys gambianus and niloticus The Balai Directive applies when rats are warranted. The small animal veterinarian (Muridae) from Senegal. Parassitologia 44: collected from the breeder and were born needs to be prepared to treat a giant rat 97–101 and kept in captivity at the breeder’s 15. Ezeifeka G O, Umoh J U, Ezeokoli C D, and should not necessarily make assump- Ezealor A U 1987 Prevalence of Ife virus premises, and PETS Passport allows an tions that regimens are the same as infection in wild rodents and birds from individual to transport up to 5 rats in and those for the domestic rat or the . Zaria, Nigeria. Journal of Wildlife Diseases 23: out of the UK, with no legal requirements 663–665 for quarantine. Movement between Euro- ACKNOWLEDGEMENTS 16. Halcrow J G 1958 The giant rat of East pean Union (EU) countries or into the EU Veterinarians Dr J Horrocks in the UK Africa. Nature 181: 649–650 from Andorra, Iceland, Liechtenstein, 17. Herder S, Simo G, Nkinin S, Njiokou F 2002 and Dr R Cooper in Zimbabwe provided Identification of trypanosomes in wild Monaco, Norway, San Marino, Switzer- advice on diseases and treatment. animals from southern Cameroon using land and the Vaticanare not subject to any the polymerase chain reaction (PCR). Para- requirements with regard to . When REFERENCES site 9: 345–349 imported into the UK directly from any 1. Adegoke G O, Ojo M O, Adetosoye A I 1985 18. Hill W A, Randolph M M, Lokey S J, Hayes non-EU country, pets must be licensed Serological characteristics of coagulase- E, Boyd K L, Mandrell T D 2006 Efficacy and positive staphylococci isolated from man safety of topical selamectin to eradicate into quarantine for 6 months. On 15 June and animals. 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66 0038-2809 Tydskr.S.Afr.vet.Ver. (2008) 79(2): 62–66