The prevalence of ocular lesions associated with hypertension in a population of geriatric cats in Auckland, New Zealand

Abstract

AIMS: To provide an estimate of the prevalence of ocular lesions associated with hypertension in geriatric cats in Auckland, New Zealand and to evaluate the importance of examination of the ocular fundi of cats over eight years of age.

METHODS: A total of 105 cats ≥8 years of age were examined and clinical signs recorded. Blood was collected for the laboratory measurement of the concentrations of blood urea nitrogen (BUN), glucose and creatinine in serum, urine was collected for determination of urine specific gravity (USG), and blood pressure (BP) was measured using high definition oscillometry equipment. A cat was determined to have systemic hypertension with a systolic BP ≥160 mm Hg and a diastolic BP ≥100 mm Hg. Each animal had an ocular fundic examination using a retinal camera to diagnose ocular lesions associated with hypertension, including retinopathies, choroidopathies and optic neuropathies.

RESULTS: Blood pressure was successfully recorded in 73 cats. Of these, 37 (51%) had no hypertensive ocular lesions and no underlying disease diagnosed, 24 (33%) had no hypertensive ocular lesions detected, but underlying disease such as chronic kidney disease, hyperthyroidism or diabetes mellitus was diagnosed, and 12 (16%) cats had evidence of hypertensive ocular lesions. Ten of the cats with hypertensive ocular lesions were hypertensive at the time of the first visit and two were normotensive. One additional cat had hypertensive ocular lesions, but it was not possible to obtain consistent BP readings in this animal. Chronic kidney disease was the most commonly diagnosed concurrent disease in cats with hypertensive ocular lesions (n=6). Mean systolic BP for cats with hypertensive ocular lesions (168.0 (SE 6.29) mm Hg) was higher than for those with no ocular lesions (144.7 (SE 3.11) mm Hg) or those with no lesions but with underlying disease (146.0 (SE 4.97) mm Hg) (p=0.001).

CONCLUSIONS: Ocular fundic examination of cats over eight years of age allows identification of cats with hypertensive ocular lesions, often before the owner or veterinarian is aware the cat has a problem with its vision. This may result in diagnosis of systemic hypertension allowing early treatment and resolution of lesions.

CLINICAL RELEVANCE: The current study demonstrates that ocular lesions resulting from hypertension occur frequently enough in cats in Auckland to support the recommendation for fundic examination in cats over eight years of age as part of the routine physical examination.

KEY WORDS:

• Cat
• hypertension
• fundus
• ocular lesions
• Optibrand

Acknowledgements

Thank you to Blair Crosbie of Vet Service Group who organised the lease of the Optibrand camera for me to undertake the study. I am also grateful to all the clients who allowed their cats to be included in the study.