INTRODUCTION

The medical management of giant pandas has advanced significantly in recent years due to cooperative programmes between Chinese and western institutions, specifically zoos and breeding centres. Key to these partnerships have been veterinarians who have become committed to understanding the diseases affecting this species. Progress has emanated from efforts such as the Biomedical Survey (see Chapter 4) and international personnel exchanges related to giant panda loans to western zoos (see Chapter 22). The result has been many opportunities for veterinarians working with giant pandas to share philosophies, tools, expertise and knowledge which, in turn, have vastly improved medical care of this species in captivity.

There are unique as well as overlapping medical issues impacting the giant panda according to age. For example, Chapter 13 has already addressed health-related topics facing neonates and juveniles. After four years of age, however, the giant panda has matured physically and sexually, leaving behind many of the diseases associated with its youth. Then, after the age of 20 years and during the period of reproductive senescence, another set of potential problems face managers and veterinarians – degenerative changes related to the geriatric condition. Because health and reproduction are improving so rapidly in the ex situ panda population, it is a given that more animals will live longer, requiring more sophisticated veterinary management to ensure well-being for up to 25 years of age or beyond.

This chapter describes the authors' medical experiences with adult and aged giant pandas living in zoos, especially in the USA.

INTRODUCTION

Historically, the breeding of giant pandas in ex situ programmes has been difficult due to behavioural incompatibility and interanimal aggression. Because some individuals fail to mate naturally, the potential loss of valuable genes is a major concern to effective genetic management (see Chapter 21). Consistently successful artificial insemination (AI) would allow incorporating genetically valuable males with behavioural or physical anomalies into the gene pool. This strategy becomes even more powerful when used in the context of a genome resource bank (GRB), an organised repository of cryopreserved biomaterials (tissue, blood, DNA and sperm) (see Chapter 7). The use of sperm cryopreservation and AI allows the movement of genes among zoos and breeding centres without needing to transfer animals, which is both stressful and costly.

‘Assisted breeding’ refers to the tools and techniques associated with helping a pair of animals propagate, from AI to embryo transfer to cloning, among others (Howard, 1999; Pukazhenthi & Wildt, 2004). With the exception of AI, there is not much need for most other assisted-breeding techniques for the giant panda. As will be demonstrated here, AI is quite adequate for dealing with most cases of infertility or with helping to maintain adequate gene diversity in the captive population. In fact, the major breeding facilities, especially the China Conservation and Research Centre for the Giant Panda (hereafter referred to as the Wolong Breeding Centre) and the Chengdu Research Base of Giant Panda Breeding, routinely use AI to increase pregnancy success.

INTRODUCTION

Among eutherians, ursids have a significant disparity between maternal weight and neonatal weight (Leitch et al., 1959). The giant panda also produces a smaller litter mass relative to maternal body mass than, for example, the American black bear (Oftedal & Gittleman, 1989; Ramsay & Dunbrack, 1996; Zhu et al., 2001). The giant panda neonate is particularly altricial (i.e. highly dependent on parental care), requiring 24-hour care during the first weeks of life. This chapter deals with the issues and intricacies associated with the newborn giant panda cub, including hand-rearing and medical management.

NEONATAL CARE AND HAND-REARING: METHODS, RESULTS AND RECOMMENDATIONS

Indications for hand-rearing

Although maternal care is always preferred for the giant panda cub, there are situations when human care-giving is mandatory. The most obvious is maternal abandonment, which usually becomes apparent within the first five to ten minutes of birth. A female that abandons her cub will typically leave it on the ground and move away, showing little or no interest. Intervention is also required when the dam holds the cub improperly (malpositioning). Such a cub can neither nurse nor rest, often moves about excessively (in an attempt to achieve proper positioning on its own) and then can fall to the ground. A third complication is the common production of two or more cubs (mean litter size is 1.7; range 1–3) (Schaller et al., 1985).

INTRODUCTION

The giant panda is seasonally monoestrus, experiencing a single oestrus with spontaneous ovulation in the spring (Schaller et al., 1985). Although natural breeding produces the majority of cubs in captivity (Xie & Gipps, 2001), the number of sexually competent breeding males is insufficient to create or maintain a genetically diverse population (Hu, 1990; Xie & Gipps, 2001). Inclusion of males that are behaviourally incapable of mating, but that are genetically valuable, is possible through artificial insemination (AI) (see Chapter 20). Accurate monitoring of the oestrous cycle to pinpoint the time of ovulation is critical for timed matings and, especially, AI success.

The vaginal epithelium of many mammalian species is responsive to changes in circulating oestrogen concentrations. The value of vaginal cytology in monitoring the oestrous cycle of rodents (Zylicz et al., 1967; Parakkal, 1974) and domestic carnivores (Shutte, 1967; Mills et al., 1979) is widely recognised. In routine practice, evaluating vaginal cytology in these taxa involves quantifying proportions of mature exfoliated epithelial cells, also known as superficial, cornified or keratinised cells. Increasing proportions of mature cells are correlated with the pre-oestrual rise in oestrogen as well as oestrous behaviours.

Despite the logistical difficulty of obtaining vaginal cells from most wildlife species, the oestrous cycles of several small carnivores (raccoon dog: Valtonen et al., 1977; river otter: Stenson, 1988; tayra: Poglayen-Neuwall et al., 1989; multiple ferret species: Mead et al., 1990; Williams et al., 1992; mink: Klotchkov et al., 1998; fox: Boue et al.

INTRODUCTION

The goal of the giant panda ex situ breeding programme is to produce healthy, genetically diverse and reproductively sound offspring. However, reproduction in this species has been poor, in part, due to lack of male libido or aggressive behaviours towards conspecific females. Although giant panda breeding facilities have made progress in producing more surviving young, only about 29% of captive male giant pandas have ever sired offspring (Lindburg et al., 1998), and most of these males were wild born. Of the 104 giant pandas in the ex situ population in China in 1996 (at the time of the first masterplanning meeting in China; Zheng et al., 1997; see also Chapter 2), there were 33 adult males of reproductive age (6–26 years old). Only five (15.2%) had ever mated naturally and sired young. This was the main reason for ‘male reproduction’ being a primary target of the Biomedical Survey conducted under the umbrella of the Conservation Breeding Specialist Group (CBSG) (see Chapter 2).

We had three goals, the first being to measure the presence or absence of any obvious physiological or anatomical abnormalities. The second was to learn more about species reproductive biology, specifically comparing males of different ages, successful versus unsuccessful breeders and wild-born versus captive born. Our approach also allowed a third opportunity: studies that would enhance our understanding on how better to use male gametes (sperm) to advance genetic management (see Chapter 21). In this case, our focus was on:

1. sperm morphology and acrosomal integrity;

2. testes development during the breeding season;

3. […]

INTRODUCTION

The Giant Panda Biomedical Survey sought to establish a baseline of scientific information on giant pandas living in Chinese zoos and breeding centres as a first step towards establishing a self-sustaining captive population (Zheng et al., 1997; see also Chapter 2). To produce the most information that would allow an understanding of the health and reproductive status of the extant population, we chose an interdisciplinary approach to examine as many health and reproductive traits as possible. What was crucial was the trusting relationship that developed early in the process between the Chinese and American teams which led to a thorough understanding of giant panda biology – information that not only was fascinating from a scholarly perspective but also valuable to improving ex situ management.

This chapter provides detailed methods and medical findings following the assessment of more than 60% of the living Chinese population of giant pandas (as existed in 1996 when the need for a Biomedical Survey was recognised). The results in this chapter address issues ranging from disease conditions to reproductive compromise, all of which ultimately allowed classifying each animal as to its usefulness in achieving the goal of population self-sustainability. The practices and reference values described here will also be useful to those who are interested in closely studying and managing giant pandas in the future.