Case Studies of the Impacts of Cataract Surgery on Crested Penguin Welfare

Characterisation of cataracts and other ophthalmic findings in various species of captive penguins

BACKGROUND

The identification of ophthalmic diseases that affect vision and/or cause discomfort should be a priority in captive penguins to improve their overall health and quality of life.

METHODS

A routine ophthalmological examination was performed on 80 clinically normal penguins (160 eyes), and any lesions observed were recorded.

RESULTS

Ocular lesions were frequent (56% of penguins), with cataracts being the most common (48.8% of penguins). Cortical cataracts (63% of eyes) and posterior subcapsular cataracts (27.4%) were the most commonly occurring. All maturation stages were found; incipient cataracts (52.1% of eyes with cataracts) were predominant, while Morgagnian cataracts (8.2%) were the least frequent. A correlation existed between lenticular changes and increasing age. Uveitis was present in 43.8% of eyes with cataracts, and ectropion uveae was the predominant clinical sign. Other ocular findings included blepharitis (3.8% of all eyes), corneal leukoma (5.6%) and posterior lens subluxation (7.5%).

LIMITATIONS

The small number of birds of some species prevented the comparison of ophthalmic findings between species.

CONCLUSION

This study corroborates the high prevalence of ocular lesions in captive penguins. Cataracts were frequent and age related. Most cataracts were cortical, and the predominant maturation stage was incipient. Lens-induced uveitis was a common finding. Lowered intraocular pressure was related to cataract formation.

The Benefits of Increased Space and Habitat Complexity for the Welfare of Zoo-Housed King Penguins (Aptenodytes patagonicus)

Zoos and aquariums accredited by the Association of Zoos and Aquariums embrace animal welfare as a foundational principle of habitat design. Modern habitats are designed to provide animals with choices and agency over their environment, and to encourage species-appropriate behavior and space use. In 2016, the Detroit Zoological Society opened the Polk Penguin Conservation Center, a 3065.80 m² facility that features a naturalistic design. The building was designed to optimize animal welfare by incorporating various substrates, nesting sites, and a 1234 kL pool with elements of underwater complexity. The facility houses a mixed-species group of penguins that were previously housed in a smaller habitat that opened in 1968. Between 2015 and 2022, we opportunistically monitored the behavior of ten king penguins (Aptenodytes patagonicus) as they moved back and forth between the two buildings while additional modifications were made to the new habitat. We collected 695 h of behavioral observations and 10,416 h of data from flipper-mounted time-depth recorders. We found that the king penguins spent less time engaged in aggression and more time engaged in swimming and positive social behaviors in the redesigned space. They also spent less time in proximity to other species of penguins and more time alone. These behavioral trends suggest that increased space and environmental complexity had positive welfare benefits for these penguins.

Bilateral cataract surgery in a Japanese macaque (Macaca fuscata): A case report

A 7.5-year-old intact male Japanese macaque was presented for evaluation of vision loss. After a complete ophthalmic examination, the patient was diagnosed with hypermature cataract in both eyes. After the cataract surgery, it was able to locate food and walk in a straight line.

Treatment with chloroquine is retinotoxic in captive African penguins (Speniscus demersus). Attenuation and recovery of electroretinographic responses

PURPOSE

To evaluate the effect of prophylactic anti-malarial chloroquine treatment, and its cessation, on electroretinographic (ERG) responses of captive African penguins.

METHODS

A brief ERG protocol ("QuickRetCheck") was recorded under mesopic conditions with manual restraint and no sedation or pupil dilation. Birds were recorded on two separate occasions, first while being treated with a daily chloroquine dose of 10 mg/kg for 12 days (n = 15, treatment group) and second after 4 months without chloroquine treatment (n = 6, off-treatment group). Three birds were recorded on both occasions. Three other birds from the flock that died were studied histopathologically.

RESULTS

Scotopic responses were unmeasurable in either recording and therefore were not analyzed. Mean a- and b-wave amplitudes of the mixed rod-cone responses to standard (3 cd·s/m² ) and high (10 cd·s/m² ) intensity flashes were higher in the off-treatment group. No difference in implicit times was observed. Sex, age, and number of previous chloroquine treatments did not affect ERG responses. Histopathology revealed Plasmodium spp.in the lungs, liver, and brain, but not in the eyes, of the necropsied birds, and there were no signs of retinitis or retinopathy.

CONCLUSIONS

Daily chloroquine treatment was associated with attenuated ERG responses in penguins, which improve following cessation of treatment. Further work is warranted to establish a chloroquine dose that is efficacious yet has minimal adverse effects. Our results suggest that ERG responses of captive penguins undergoing ERG for any indication (such as prior to cataract surgery), must be evaluated in light of the birds' anti-malaria treatment status.