Blood pressure in small animal patients is important to monitor, as it is commonly overlooked until target organ damage has already occurred. The organs most commonly affected by high blood pressure include the eyes, heart, kidneys and brain. High blood pressure in dogs and cats is most often due to other systemic disease such as kidney disease, Cushing’s disease, or hyperthyroidism. It is important to include blood pressure readings during examinations, especially in patients with signs of target organ damage, animals diagnosed with the common underlying causes of systemic hypertension, and geriatric patients (over 8 years of age). Blood pressure is a product of cardiac output and systemic peripheral resistance. The relationship between the kidneys, autonomic nervous system, and endothelial intercellular messaging systems all contribute to a patient’s blood pressure.
Fortunately, there are affordable and simplistic methods of monitoring blood pressure in the small animal practice. There are two methods to measuring blood pressure in small animals:
Technique for indirect monitoring:
The room should be kept as quiet as possible, and technicians should move slowly and comfort the patient, to decrease the “white-coat effect”.
|SPECIES||WHEN TO TREAT|
|Canine||Systolic BP consistently >180mmHg
Systolic BP >160mmHg if certain clinical signs are present and/or metabolic conditions that may result in secondary hypertension such as hyperthyroidism, protein losing nephropathy, diabetes mellitus, etc.
|Feline||Systolic BP consistently >200mmHg
Systolic BP >180-200mmHg if certain clinical signs are present and/or metabolic conditions that may result in secondary hypertension such as hyperthyroidism, protein losing nephropathy, diabetes mellitus, etc.
|Table 1: Guidelines for Treatment of Hypertension in Small Animals|
Treatment options for hypertension include dietary and medicinal intervention. In some cases where caloric intake is not a concern, a low sodium diet of <0.25% sodium on a dry-matter basis (along with adequate protein) may be recommended. Weight loss is also important in keeping blood pressure levels normal. Most patients with high blood pressure will need medical treatment. In some cases, simply treating the underlying disease (ex. Hyperthyroidism) will cause the blood pressure to return to normal.
Please refer to table 2 below for medical treatment of hypertension in small animals. In addition to the interventions listed, other therapies may include hydralazine and phenoxybenzamine. Diuretics are commonly used in treatment of human hypertension, but are not used as frequently in veterinary medicine.
|Feline: 0.625-1.25mg (total dose) PO QD-BID;
Canine: 0.05-0.5mg/kg PO QD-BID
|Usually first line anti-hypertensive agent in vet med; May advocate using along with ACE inhibitors|
|ACE inhibitor||Feline: 0.5mg/kg PO QD;
Canine: 0.5mg/kg PO BID
|Usually used with other agents to control BP; Will be used to treat protein-losing nephropathy|
|Atenolol||Beta Blocker||Feline: 6.25-12.5mg/cat PO QD-BID;
Canine: 0.5-1.0mg/kg PO BID
|Usually used with other agents to control BP; May be used in cats with hyperthyroidism if persistently tachycardic. Use with caution due to negative inotropism/risk for causing heart failure.|
|Table 2: Medicinal Treatment of Hypertension in Small Animals|
Technicians should keep in mind that clinical signs in patients with hypertension often do not show until the systolic blood pressure is greater than 180mmHg, so catching lelevated blood pressure prior to actual signs is of the utmost importance. The effects of target organ damage due to uncontrolled hypertension to the heart, eyes, brain, and kidneys can be devastating and sometimes, irreversible. For hypertensive patients beginning therapy, blood pressure should be monitored weekly until in an acceptable range. Once the blood pressure is adequately controlled, it should be rechecked every 3-4 months. Bloodwork (CBC/Chem/T4/UA) should also be checked at least every 6 months.