PHYSICAL EXAMINATION AND DIAGNOSTICS
4.1 Physical examination
Aspects of a physical examination can be performed without sedation in trained pinnipeds, including ophthalmic and oral cavity examinations and musculoskeletal palpation.
Abdominal palpation is often unrewarding, because of the size of the animals and the subcutaneous fat layer. Thoracic auscultation is less rewarding than in terrestrial animals and pinnipeds with significant pulmonary disease can have apparently normal lung sounds (van Bonn 2015).Ophthalmic examinations were performed on three female long-nosed fur seals and one female Australian fur seal at Melbourne Zoo, under trained behaviour. The examinations were performed in low-light conditions to achieve physiological pupillary dilation, as topical parasympatholytic agents do not adequately dilate pinniped pupils. The following features were present in all four animals: a tear drop-shaped pupil that dilated rapidly in a darkened environment (Plate 45.1); an obviously round, flattened area ventromedial to the axial cornea; and a hol- angiotic fundus without a non-tapetal region. The tapetum had a yellow hue in all animals and the iris was predominantly brown (Plate 45.1). Two long-nosed fur seals had specks of colour variation (white) located within the iris (Plate 45.2). There were prominent pectinate ligaments seen without magnification in all areas of the iridocorneal angle; however, these appeared slightly less prominent in the Australian fur seal (H Newman pers. comm.). The findings in these animals were similar to those described in 30 California sea-lions (Zalophus californianus) (Miller et al. 2010).
Intra-ocular pressure (IOP) measurements, using rebound tonometry, have been obtained in anaesthetised South American sea lions (Otaria byronia) and anaesthetised Peruvian fur seals (Arctocephalus australis) (Sheldon et al. 2019; Kane et al.
2021).4.2 Diagnostic imaging
A wide range of diagnostic imaging modalities is used in pinnipeds, including sonography, radiography and magnetic resonance imaging (MRI). In seals in managed care, sonography and digital radiography can be performed under trained behaviour. In addition to their use for clinical diagnosis, MRI and CT are increasingly used during forensic investigations into cases of suspected anthropogenic injury (Dennison
| Table 45.1. Thoracic radiographic anatomy of otariid seals: features of significance | |
| Thoracic radiographic features described in immature California sea-lions (Zalophus californianus) (Dennison etal. 2009) | Long-nosed fur seals (Arctocephalus forsteri) (n = 11): anatomical features noted in thoracic radiographs taken at Taronga Wildlife Hospital, Sydney, NSW |
| In the lateral view, the angle between the cardiac silhouette and the sternum is shallower than in the dog and cat | In the lateral view, the angle between the cardiac silhouette and the sternum is shallower than in the dog, but similar to the angle seen in cats >10 yr old (Fig. 45.1) |
| There is a focal, fairly symmetrical widening of the cranial mediastinum immediately cranial to the cardiac silhouette on ventrodorsal (VD) and dorsoventral (DV) views. This corresponds with the aortic bulb of the ascending aorta in pinnipeds | This feature is visible in VD/DV thoracic views; however, the structure was less distinctly visible in emaciated animals with reduced mediastinal fat (Fig. 45.2). Careful positioning will assist identification of this structure, as superimposition of scapulae may obscure it |
| The lung parenchyma has a diffuse interstitial-to- bronchointerstitial pattern, because of the presence of increased connective tissue for support of airways | This feature is visible. However, a true interstitial lung pattern can only be differentiated from artefact (an expiratory film, positional atelectasis) when careful radiographic technique is used (Fig. 45.1) |
Otariids and phocids have species-specific anatomical differences that may affect radiographic evaluation during the clinical examination. Dennison et al. (2009) described normal thoracic radiographic anatomy in immature California sea-lions and northern elephant seals (M. angustirostris) and highlighted several anatomical features of significance. Examination of thoracic radiographs from 11 long-nosed fur seals suggests that several of the features seen in immature California sealions can also be identified in long-nosed fur seals (D Tyrrellpers. comm.) (Table 45.1).
4.3 Clinical pathology
A summary of published values for haematology and biochemistry of free-ranging Australian pinnipeds and of non-published values of clinically normal, zoo-housed Australian pinnipeds can be found in Appendix 1.
Fig. 45.1. Thoracic radiograph, lateral view, sub-adult male long-nosed fur seal (Arctocephalus forsteri). The arrows mark the cranially located tracheal bifurcation. There is a normal, diffuse bronchointerstitial pattern throughout the lung fields. The angle between the cardiac silhouette and the sternum is shallower than in the dog and is similar to the angle seen in cats aged >10 yr. Image: Taronga Wildlife Hospital
McFarlane (2009) has developed baseline health data for free-ranging Weddell seals in East Antarctica, including haematology and limited biochemistry values.
5.