The behavioral husbandry program for the two giant pandas (Ailuropoda melanoleuca) housed at Ocean Park, Hong Kong has been developed since 1999, and allows veterinary procedures such as physical examination, blood collection, radiography, and ultrasonography. Since systemic hypertension and its consequences are increasingly recognized in veterinary medicine, particularly in geriatric animals, the two giant pandas (a 16-year-old male and a 24-year-old female) were trained to allow measurement of arterial blood pressure by noninvasive oscillometry.
The animals were desensitized to placing their forelimb in a metallic holder, and an oscillometric monitor (Vet/BP Plus 6500 NIBP, Heska Corporation, Waukesha, WI, USA) connected to a 15-cm wide cuff (Dura-cuf ref 2772, adult long, 23–33 cm, Critikon USA) placed around the forelimb. Blood pressure was measured twice each week over a period of 10 weeks. Systolic blood pressure, diastolic blood pressure, and mean arterial pressure in the female giant panda were on average 50–75% higher than in the male panda. Average values for the female were 241/135 mm Hg, and mean arterial pressure was 176 mm Hg. Based on comparison with the male panda housed at the same facility, with normal values of domestic species3 and anecdotal data from another geriatric panda, a tentative diagnosis of systemic hypertension was made in the female giant panda.
Results and Discussion
Primary or essential systemic hypertension is common in human beings. In domestic cats, hypertension is usually secondary to chronic renal disease and hyperthyroidism; in domestic dogs, renal glomerular and interstitial disease, hypothyroidism, diabetes mellitus and hyperadrenocorticism have been associated with secondary hypertension.2,3 The only clinical sign reported in this female possibly related to systemic hypertension is an episode of epistaxis. Ongoing evaluations do not currently demonstrate the presence of any underlying condition in this animal.
Hypertension can irreversibly damage organs with rich arteriolar supply, such as ophthalmic, renal, cardiovascular and cerebrovascular tissues. It was decided to initiate therapy, as this female giant panda presented with persistently elevated blood pressure. Amlodipine besylate, a long-acting calcium channel blocker, has been used successfully as a single agent in hypertensive domestic cats.1,2 It is also commonly used as monotherapy in the treatment of essential hypertension in human beings and is considered to have few adverse effects. Ankle edema is the most common adverse effect in human beings.1 A dose of 7.5 mg of amlodipine (Norvasc, Pfizer, West Ryde, Australia) PO (equivalent to 0.093 mg/kg bodyweight) administered as a single daily dose in this female giant panda resulted in a reduced systolic blood pressure, diastolic blood pressure and mean arterial pressure, and no adverse effects were observed. This dose may need to be reviewed as more data obtained in conscious, healthy giant pandas becomes available and allows establishment of a reference range for blood pressure values in this species.
The authors wish to thank the giant panda trainers Jason Tang, Paul Ng and Jacky Chui for their dedication and patience, which made this work possible.
1. Cooke, K.L. and P.S. Snyder. 1998. Calcium channel blockers in veterinary medicine. J. Vet. Intern. Med. 12:123–131.
2. Henik, R.A. 1997. Systemic hypertension and its management. Vet Clin North Am: Small Anim Pract. 1355–1372.
3. Stiepen, R.L. 2000. Blood pressure measurement in dogs and cats. In Practice. March: 136–145.