IUCN Otter Spec. Group Bull. 37(2) 2020

ARTICLETHE SITUATION OF PET OTTERS IN JAPAN –WARNING BY VETS
Yumiko OKAMOTO1*, Naoki MAEDA2, Masakazu HIRABAYASHI3,
Natsumi ICHINOHE4
1

2

Hsinchu Zoo: 279, Kung-Yung Rd, Hsinchu City, Taiwan 300
Maeda Animal Hospital: 9-12, 2-Chome, Matsushita, Inazawa City, Aichi Prefecture, Japan 4928208
3All Pet Clinic: Aruta House, 2-4-9, Nishi Azabu, Minato-ku, Tokyo, Japan 1060031
4Tokyo University of Agriculture and Technology: 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, Japan
1838509*Corresponding author: email: yumikohaku88@gmail.com(Received 29th June 2019, accepted 22nd October 2019)
Abstract: Clinical data for 20 pet otters treated at two animal hospitals in Japan wascollected from August 2010 to May 2019. Most otters were in a critical condition or
already dead when they were brought to the hospital. All otters were identified as Asiansmall-clawed otters and kept privately at the owner’s house or otter café. Nine of theotters were considered to have been imported illegally (No.4-8 and No.13). Regarding thediseases suffered, kidney stones were seen most frequently, then pneumonia and the third
was dehydration. Most of the otters looked thin due to inadequate nutrition. An
inappropriate environment was the most common cause of diseases in pet otters, followed
by inadequate nutrition and then stress. Two otters with stress-related illness were kept in
the same otter café, where petting by people unknown to them could have caused theircondition. Although laws regarding to Asian small-clawed otters in Japan was changed inAugust 2019 according to the change of CITES rank from II to I, the monitoring on thedomestic otter market should be kept until the situation is improved. In conclusion: firstly,
owners should be aware of basic husbandry of Asian small-clawed otters before owningone, and secondly, improvement on management system of captive otters, andenforcement of such regulations is a key factor for more effective otter protection in
Japan. From the point of view of animal welfare, the current situation of pet otters inJapan has to be improved as soon as possible to prevent more tragic deaths. We hope that
this information can contribute to a better management and protection of otters.
Citation: Okamoto, Y., Maeda, N., Hirabayashi, M. and Ichinohe, N. (2020). The
Situation of Pet Otters in Japan – Warning by Vets. IUCN Otter Spec. Group Bull. 37 (2):71 - 79
Keywords: Disease, Management of wildlife, Veterinary, Wildlife law, Welfare

INTRODUCTION
As many articles report, otters are becoming one of the most popular animals inJapan these days (New York Times, 2019). However, too much popularity is causing
many serious problems such as the illegal pet trade, poaching or business use forcommercial facilities including otter cafés (McMillan, 2018, Kitade and Naruse,2018). One of the biggest reasons that Japan has become a hot spot of the otter trademust be because of the high retail price of otters: it has reached over 300 times thereported black market price in Thailand (USD 30 in Thailand compared to USD 9,000
per juvenile or more in Japan) (Kitade and Naruse, 2018).
Usually, the Asian small-clawed otter (Aonyx cinereus) is kept as an individual
pet or exhibited in otter cafés in Japan. This species was formerly listed on CITES
Appendix II before August 2019, and is not protected under the Law for theConservation of Endangered Species of Wild Fauna and Flora that regulates domestic- 71 -

IUCN Otter Spec. Group Bull. 37(2) 2020

trade of animals in Japan (McMillan, 2018). In addition to the unregulated trade, there
is no domestic registration system or husbandry guidelines for pet otters in Japan,
which makes it much easier to keep this species in captivity than in countries withsuch systems. To change this situation, the Japanese government declared on August
2019 that the Asian small-clawed otter will be designated as an ”International
Endangered Species of Wild Fauna and Flora” under the domestic law and domestic
otter trade would have been restricted from November 2019 according to theinternational decision that the CITES Appendix rank of this species was changed fromII to Ⅰ.
It must be admitted that otters are very attractive animals, and extremely
photogenic. In Japan, whilst buying an otter was easy, it is difficult for people to keep
one correctly in private properties because otters need a large space, a semi-aquatic
environment and a variety of foods, up to 20% of their body weight per day (Heap etal., 2008). In addition, the faeces have a strong smell, and the animal has sharp teeth
and powerful jaw muscles, capable of cracking crustacean shells. The Asian smallclawed otter is also highly social, and requires either others of its species in a stablegroup, or intensive interaction with its owner. In short, it is completely unsuitable forprivate ownership in urban environments, and require specialized, and expensive
conditions on more rural properties.
However, little information on how to keep pet otters correctly, and on the
medical conditions they experience is available in Japan, and the demand for petotters has kept growing through the influence of social media (New York Times,2019). To reveal the truth and discourage the inappropriate private keeping of otters, asurvey on pet otters treated at animal hospitals in Japan was conducted and ispresented in this report.
APPROACH
Clinical data on privately owned otters was collected at two animal hospitals in
Nagoya and Tokyo, Japan from August 2010 to May 2019. In addition to basic
information about the treated otters (age, sex, body weight and disease), the estimatedcause of disease and other features have been recorded. However, age is only basedon the owner’s information.
RESULTS AND DISCUSSION
In total, 20 cases of pet otter treatment were recorded and most of the otterswere in a critical condition or already dead when they were brought to hospital (Table
1). All otters were identified as Asian small-clawed otters and had been kept privately
at the owner’s house or at an otter café.
Many serious diseases were observed, such as kidney stones (Figure 1),
dehydration and pneumonia (Figure 2), bite injuries (Figure 3), dental problems(Figure 4) and alopecia (Figure 5). In decreasing order of frequency, kidney stones
were observed most often, then pneumonia, and third was dehydration (Figure 6).
Most otters looked skinny and one 4-month old otter (No. 14) was especiallyemaciated, weighted only 450g. Based on studbook database, this is almost the same
body weight as a 50-day old otter. In addition to that, there was no food left in thestomachs of two dead otters (No. 2 and 3), and the gallbladder of No. 3 was evenenlarged due to chronic hunger. The average age at death of these otters was only 1
year and 7 months, which is much shorter than the normal 10-15 year life span in
captivity (Perdue et al., 2013).

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IUCN Otter Spec. Group Bull. 37(2) 2020

Table 1. Data on otters treated at two animal hospitals in Japan from August 2010 to May 2019.

Figure 1. A female otter (No.1) which was fed only cat foods and human biscuits, died due to renal
failure probably because of the high salt level in its diet. On the x-ray quite a lot kidney stones could be
seen.

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IUCN Otter Spec. Group Bull. 37(2) 2020

Figure 2. An otter cub (No. 4) which died because of dehydration and pneumonia, which occurred
during importation.

Figure 3. A female otter (No. 12) seriously injured due to a bite by a male otter companion.

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IUCN Otter Spec. Group Bull. 37(2) 2020

Figure 4. A male otter (No. 16) kept in the otter café had serious dental problems, including clear
evidence of caries.

Figure 5. A female otter (No. 17) had alopecia which might have occurred directly because of thestress of petting by strangers at the otter café, but can also be caused by malnutrition.

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IUCN Otter Spec. Group Bull. 37(2) 2020

Figure 6. Diseases of treated or dead otters observed during this survey.

Figure 7. Main causes of diseases and injuries in otters observed during this survey.

In terms of the causes of these diseases, an inappropriate captive environment,such as low temperatures, no access to water for exercise, or incompatible breeding
partner were the most frequent causes (58%). Secondly, many diseases such as kidneystones and hematochezia (blood in stool) occurred due to inadequate nutrition.
Especially, from the 20 animals, 5 have been cubs under 3 months of age. It isquestionable if these cubs got an adequate milk replacement because they still would
have needed normally their lactating mothers. Weaning time in this species is witharound 80 days / 3 months. But also in older otters, some owners even simply did notgive large enough amounts of food to their otters. Sometimes on purpose, to makeotters have less strong-smelled faeces. Thirdly, symptoms of mental problems werealso observed, for example; the self-mutilation injury and alopecia. Two otters withthese stress-related symptoms were all kept in the same otter café and it is believed by- 76 -

IUCN Otter Spec. Group Bull. 37(2) 2020the veterinarian that petting by unknown people for long hours caused huge stress forthe animals.
The Asian small-clawed otter normally lives 10-15 years and up to 20 years in
captivity (Perdue et al., 2013). However, the average age of otters at death observed inthis study was only 1 year and 7 months, which is very short- they have barely
achieved maturity. To determine exactly how inappropriate feeding affected the ottersin this study is difficult, because it is known that Asian small-clawed otters often
develop kidney stones (urolithiasis/nephrolithiasis) in captivity even under good
husbandry conditions and even in young age (Petrini et al., 1999, Bochmann et al.,2017). However, while wild otters forage for a wide variety of foods items including
fish, crustaceans, crabs, snails, mollusks, frogs or small birds (Heap et al., 2008),
these pet otters were normally only fed on cat foods or human foods with high saltcontent. It is recommended to feed otters in captivity a diet similar (around 60%) to
their wild one and avoid foods containing red meat proteins and salt in highconcentration as in cat foods, dog biscuits and kibbles (Jason Palmer, pers. comm).
Hence, it is estimated that the wrong feeding have caused serious nutritional problems
in these otters.
Otters and the Law in JapanLaw enforcement is very important as an effective tool to protect wildlife.
Japanese laws regarding to Asian small-clawed otters are listed here.
Import; in Japan, the international wildlife trade is normally regulated by the Foreign
Exchange and Foreign Trade Act and Customs Law. Under these laws, people
currently cannot import the Asian small-clawed otters from the wild except withacademic purpose or individuals bred in captivity or got properly before August 2019.
Among the 20 cases observed in this study, nine otters were thought to have been
imported illegally because their owners faced criminally charges later (No. 4-8 andNo. 13).
Domestic trade; As mentioned above, domestic trade of CITES Appendix I species istightly controlled under the Law for the Conservation of Endangered Species of Wild
Fauna and Flora. Because of the CITES rank upgrade from II to I of the Asian smallclawed otter and this species was designated as an ”International Endangered Speciesof Wild Fauna and Flora” under this domestic law on August 2019. The domestic
otter trade would have been restricted and people have to obtain the registration form
when trading from November 2019. However, the trade is still possible under thissituation; 1) individuals born under parents with registration 2) individuals obtained in
the domestic market before the law regulation changes 3) individuals imported under
the permission of Customs Law.
Private keeping; all pet animals including otters should be kept well with a suitableenvironment under the Act on Welfare and Management of Animals. Also, people
have to register the pet otter on CITES I under the Law for the Conservation ofEndangered Species of Wild Fauna and Flora from November 2019. Although it
seems to be the best solution to control the pet otter market, however, there is anotherrisk that all otters in Japan including poached individuals will be registered as proper
imported or captive bred individuals.
For the better captive management and prevention of tragedies occurring with
pet otters in this country, the monitoring should be kept even after the laws on ottersin Japan were improved in 2019.

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IUCN Otter Spec. Group Bull. 37(2) 2020

CONCLUSIONS
While the critical threat to the illegal otter, and the increasing commercial use ofotters in cafés in Japan have been becoming clear in recent years, the actual welfare
state of the owned otters was almost unknown due to the lack of a registration ormonitoring system by the government. In this paper, we reveal the first sight of theinappropriate management and poor welfare state of privately kept pet otters in Japan.
RECOMMENDATIONSFirstly, information about basic husbandry of Asian small-clawed otters should
be prepared and disseminated to would-be owners so that they can have easily accessto these information before they buy a pet otter. Probably husbandry guidelines,
which exist already in other countries, could be translated and set on otter pages in theinternet so that they would be available for everyone who is interested. However, it
should be recommended sharply, otters not to use as pets in normal households or as
petting animals. The survey showed that many otters are, through ignorance of theirneeds, kept in poor environments with inadequate nutrition, causing the tragic deathsof many animals. The information collected in just two animal hospitals is the tip of
the iceberg and further investigation is necessary. Especially the findings of very
young animals (1-2 months old) show, that there is absolutely no knowledge about
nutrition, because juveniles in this age are still dependent on their mothers. They willbe nursed at least until 80 days. So as recently as an age of nearly 3 month they startto eat solid food.
Secondly, the enforcement of management system on captive otters is a key
factor for the more effective protection of otters in Japan. Although registration on
captive otters will be started from November 2019 according to the changes ofdomestic laws, however, there is another risk that all otters in Japan including
poached individuals can be registered as proper imported or captive bred individuals.
To prevent this situation, the application for registration should be strictly examinedby the Japanese government. Also, inspection of the captive environment andhusbandry regime for a proposed pet otter could prevent the casual acquisition of ananimal with complex needs, and lead to a decline in popularity of otter keeping andthe demand for them as pets. Regarding to the international otter trade, it is stillconcerned that otters could be imported under the CITES regulation exception that;
Article VII of CITES states that species listed in Appendix I that are bred in captivity
for commercial purposes are treated as Appendix II. In addition to otters, many otherexotic species are currently kept privately as pets (McMillan, 2018), so the wholelegal system regarding to wildlife keeping should therefore be reconsidered and themonitoring should be kept on the international and domestic otter trade until thesituation is completely improved.
From the point of view of animal welfare, the current situation of pet otters has
to be improved as soon as possible to prevent more tragic deaths. We hope that the
information we present here can contribute for better management and protection ofotters.
Acknowledgement - We wish to thank all the people who cooperated with us, and Kaori Fujita and
Sakura who gave us professional veterinary advices. We also would like to show our appreciation to
Jan Reed-Smith, Meredith Knott and Sarah Duncan who shared otter information for this study.

REFERENCES
Bochmann, M., Steinlechner, S., Hesse, A., Dietz, H.H., Weber, H. (2017). Urolithiasis in free-rangi
ng and captive otters (Lutra lutra and Aonyx cinerea) in Europe. J. Zoo. Wildl. Med. 48, 725-73
1.

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Heap, C.J, Wright, L., Andrews L. (2008). Summary of Husbandry Guidelines for Asian Smallclawed Otters in Captivity. IUCN/SSC Otter Specialist Group, Otters in Captivity Task Force.
Kitade, T., Naruse, Y. (2018). OTTER ALERT, A rapid assessment of illegal trade and booming
demand in Japan. TRAFFIC, Japan.
McMillan, E.S. (2018). TOO CUTE! THE RISE OF OTTER CAFÉS IN JAPAN. IOSF. 4. pp. 23-28.
New York Times. (2019). These Otters Are Popular Pets in Asia. That May Be Their Undoing. (https://www.nytimes.com/2019/04/22/science/asia-otters-pets-japan.html) Downloaded on June 18th, 2019.
Perdue, B.M, Snyder, R.J., Maple, T.L. (2013). Cognitive Research in Asian Small-Clawed Otters.
Int. j. comp. psychol. 26. pp. 105-113.
Petrini, K.R, Lulich, J.P, Treschel, L., Nachreiner, R.F. (1999). Evaluation of urinary and serum
metabolites in Asian small-clawed otters (Aonyx cinerea) with calcium oxalate urolithiasis. J.
Zoo. Wildl. Med. 30, 54-63.

RESUMELA SITUATION DES LOUTRES, COMME ANIMAL DE COMPAGNIE, AU JAPON – UNE
MISE EN GARDE DES VÉTÉRINAIRES
Des données cliniques concernant 20 loutres, animaux de compagnie, soignées dans deux hôpitauxvétérinaires au Japon ont été recueillies d'août 2010 et mai 2019. La plupart des loutres étaient dans unétat critique ou étaient déjà mortes lorsqu'elles ont été transférées à l'hôpital. Toutes les loutres ont été
identifiées comme étant des loutres cendrées gardées par un propriétaire privé ou dans un « Café àloutres ». Neuf de ces loutres ont été considérées comme importées illégalement (n ° 4 à 8 et n ° 13).
En ce qui concerne les maladies dont elles souffrent : les calculs rénaux sont les plus fréquents, vientensuite la pneumonie et en troisième lieu la déshydratation. La plupart des loutres semblaient maigresde par une nutrition inadaptée. La cause la plus fréquente des maladies chez les loutres de compagnieétait liée à un environnement inapproprié, suivi d'une nutrition inadaptée et ensuite le stress. Deux
loutres souffrant de maladie liée au stress ont été placées dans le même «Café à loutres», où descaresses de personnes inconnues auraient pu être la cause de leur stress. Bien que les lois concernant les
loutres asiatiques au Japon aient été modifiées en août 2019 en fonction du passage de l’annexe II àl’annexe I de la CITES, la surveillance du commerce de la loutre comme animal de compagnie sur lemarché intérieur devrait être maintenue jusqu’à ce que la situation se soit améliorée. En conclusion :premièrement, les propriétaires doivent être informés des règles de base de l’élevage des loutres
cendrées avant d’en acquérir une, et deuxièmement, l’amélioration du système de gestion des loutres
captives et un renforcement de la régulation sont un facteur clé pour une protection plus efficace desloutres au Japon. Au point de vue du bien-être des animaux, la situation actuelle des loutres au Japon,
comme animal de compagnie, doit être améliorée dès que possible pour éviter des mortalités plus
tragiques. Nous espérons que ces informations pourront contribuer à une meilleure gestion et protection
des loutres.

RESUMENLA SITUACIÓN DE LAS NUTRIAS COMO MASCOTAS EN JAPÓN – UNA ADVERTENCIA
DE LOS VETERINARIOSColectamos datos clínicos de 20 nutrias-mascotas en dos hospitales animales en Japón, de Agosto 2010a Mayo 2019. La mayoría de las nutrias estaban en condición crítica o ya muertas cuando fueron
ingresadas al hospital. Todas las nutrias fueron identificadas como Nutrias Asiáticas de Uñas Pequeñas,
y mantenidas en cautiverio en forma privada en una casa o en un “café de nutrias”. Nueve de las nutrias
se supone que fueron importadas ilegalmente (No. 4-8 y No. 13). En cuanto a las enfermedades, lo más
frecuente que vimos fueron piedras en los riñones, luego neumonía, y la tercera deshidratación. La
mayoría de las nutrias estaban muy flacas, debido a nutrición inadecuada. La causa más común de lasenfermedades en nutrias-mascotas fue su ambiente inadecuado, seguido por nutrición inadecuada yluego stress. Dos nutrias con enfermedad relacionada con el stress estaban en el mismo café de nutrias,
y las caricias por gente desconocida podría haber causado su condición. Aunque en Agosto de 2019 fue
modificada la legislación relacionada con las nutrias asiáticas de uñas pequeñas (pasaron del Apéndice
II de CITES al I), el monitoreo del mercado de nutrias domésticas debería ser mantenido hasta que
mejore la situación. En conclusión: en primer lugar, los dueños deberían tener conocimientos en
cuidados básicos de nutrias asiáticas de uñas pequeñas antes de tener una, y en segundo lugar, elmejoramiento en el sistema de manejo de nutrias en cautiverio, y la fiscalización de esas regulaciones,
es un actor clave para la protección más efectiva de las nutrias en Japón. Desde el punto de vista delbienestar animal, la actual situación de las nutrias-mascotas en Japón tiene que mejorar lo más pronto
posible para prevenir más muertes trágicas. Esperamos que esta información pueda contribuir a un
mejor manejo y protección de las nutrias.

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