ISFM Consensus Guidelines on the Diagnosis and Management of Hypertension in Cats

Abstract

Practical relevance: Feline hypertension is a common disease in older cats that is frequently diagnosed in association with other diseases such as chronic kidney disease and hyperthyroidism (so-called secondary hypertension), although some cases of apparent primary hypertension are also reported. The clinical consequences of hypertension can be severe, related to 'target organ damage' (eye, heart and vasculature, brain and kidneys), and early diagnosis followed by appropriate therapeutic management should help reduce the morbidity associated with this condition. Clinical challenges: Despite being a common disease, routine blood pressure (BP) monitoring is generally performed infrequently, probably leading to underdiagnosis of feline hypertension in clinical practice. There is a need to: (i) ensure BP is measured as accurately as possible with a reproducible technique; (ii) identify and monitor patients at risk of developing hypertension; (iii) establish appropriate criteria for therapeutic intervention; and (iv) establish appropriate therapeutic targets. Based on current data, amlodipine besylate is the treatment of choice to manage feline hypertension and is effective in the majority of cats, but the dose needed to successfully manage hypertension varies between individuals. Some cats require long-term adjuvant therapy and, occasionally, additional therapy is necessary for emergency management of hypertensive crises. Evidence base: These Guidelines from the International Society of Feline Medicine (ISFM) are based on a comprehensive review of the currently available literature, and are aimed at providing practical recommendations to address the challenges of feline hypertension for veterinarians. There are many areas where more data is required which, in the future, will serve to confirm or modify some of the recommendations in these Guidelines.

Figure 1

Overview of some of the important mechanisms involved in the regulation of blood pressure. RAAS = renin–angiotensin–aldosterone system

Figure 2

SBP 182 mmHg. Left eye. Dorsal to the optic nerve head is substantial fresh vitreal haemorrhage. There are also some areas of retinal thinning and laterally there is retinal degeneration

Figure 3

SBP 172 mmHg. Left eye. Note the generalised tapetal retinal oedema and retinal vessel attenuation. Throughout the tapetal fundus there are areas of hyperreflectivity due to retinal thinning and hyporeflectivity because of localised retinal oedema

Figure 4

SBP 170 mmHg. Left eye. There is a large bullous retinal detachment, with several smaller foci of detachment lateral to this. Throughout the fundus are multifocal areas of pigmentary disturbance

Figure 5

SBP 195 mmHg. The right eye of this cat has vitreal haemorrhages present; the fundus was not visible

Figure 6

SBP 167 mmHg. Left eye. Note the large bullous retinal lesion associated with a blood vessel; smaller bullous lesions are also present. This eye had an intact menace response and pupillary light reflex, and was completely visual

Figure 7

Examples of (a) Doppler sphygmomanometry and (b) high-definition oscillometry (HDO) equipment

Figure 8

Positioning of the cuff for blood pressure measurement. Forelimb (a) and tail (b) for Doppler measurement; tail (c) for measurement by high-definition oscillometry

Figure 9

HDO traces recorded on a computer. (a) Good trace, providing a reliable reading. (b) Poor trace showing interference (as a result of patient movement)

Figure 10

Example of a blood pressure assessment form. This document is available to download from jfms.com as a supplementary material file

Figure 11

(a) 18-year-old, female, domestic shorthair cat with an SBP of 180 mmHg. Left eye. There is a large bullous retinal detachment medial to the optic nerve head. Also focal areas of retinal oedema lateral to the optic nerve head, with an area centrally that has coalesced to form a region of serous retinal detachment. (b) Same eye, 10 weeks after commencing amlodipine besylate treatment (current dose 1.25 mg q24h). The bullous lesion has resolved and the area of serous retinal detachment appears now as a hyporeflective, thickened area of the retina