This month we are bringing attention to the issue of high blood pressure (the medical term is hypertension) which can affect pets and well as people. This disease can be difficult to diagnose because just as in people the condition may not have any outwardly visible signs and cats and dogs can also suffer from ‘white coat syndrome’. Mocha, an 18.5 year old female kitty, and Maggie, a 12.5 year old Golden Retriever are our Pets of the Month. Their stories help to illustrate how hypertension is diagnosed and what you and your veterinarian can do to evaluate your pet for this condition.
Mocha’s medical history is typical of many older cats in that she developed chronic renal failure (CRF) and thyroid disease (Hyperthyroidism) in her early teenage years. Over the years the doctors at Hawthorne Hills Veterinary Hospital have helped Mocha’s owner manage the medical conditions and for the most part Mocha has done very well. As part of monitoring and managing the changes associated with both kidney disease and thyroid disease we screen patients for high blood pressure. Mocha is also typical of many of our cats who are not terribly thrilled at being seen by the veterinarian so it has been more challenging to get reliable blood pressure readings.
Mocha’s blood pressure numbers were normal until last spring when her blood pressure increased to greater than 300 mmHg and she was started on Amlodipine to alleviate the hypertension. Luckily the pills are quite small and generally easy to hide in a bite of food.
Maggie’s story is a bit different. Earlier in life she was diagnosed with an eye condition that required evaluation by one of our local veterinary ophthalmologists. Since there are several genetic eye conditions that Golden Retrievers are prone to Maggie has continued to go for regular checkups. Oftentimes the first indication that pets have hypertension is they go blind unexpectedly. It was during a recent routine evaluation that Maggie’s hypertension was discovered. She had developed changes in the retina of her eye and her blood pressure readings were increased. Maggie is a very mellow patient at her veterinary visits so there was no concern that anxiety was altering her blood pressure readings inappropriately. At 242mmHg Maggie’s blood pressure was consistent with systemic hypertension. Maggie has been started on Enalapril and Amlodipine and we will continue to monitor her closely to ensure that her blood pressure is as well controlled as possible.
You may wonder what you can do to ensure that your pet is not suffering from hypertension. Understanding a little background can help you be a proactive part of your pet’s medical care. There are two forms of hypertension:
- Primary or ‘Essential’ hypertension – we don’t really know if this occurs in pets; studies are limited and the challenges to getting accurate readings preclude diagnosing hypertension without other signs or predisposing changes
- Secondary hypertension when the blood pressure is increased because of another disease such as kidney disease, heart disease, overactive thyroid disease, diabetes mellitus, the use of certain medications, too much salt in the diet, and other metabolic diseases. This is the form of hypertension we are most worried about in our pets.
There are two measurements typically used in people that reference our blood pressure. Systolic which is the highest number measured in the artery. It equates to the pressure exerted by the heart as it pumps blood out to the vessels. The diastolic is the lowest pressure measured in between heart contractions. Changes in the heart, blood vessels, other organs, and medications can all have an effect on the blood pressure. Most often in pets we use the systolic measurement only; again because of the challenges in getting accurate readings.
The American College of Veterinary Internal Medicine has developed four categories of risk that are used by veterinarians to help when evaluating blood pressures. The higher the blood pressure, the higher the risk category and the more likely a patient is to develop damage to organs (heart, kidney, brain, or eye) as a consequence of the hypertension.
- Normal blood pressure for dogs and cats is generally considered to be between 110-150mmHg (Category I – minimal risk)
- There is a ‘gray zone’ between 150-180mmHg (Category II-III – mild to moderate risk)
- Anything consistently over 180mmHg is considered hypertensive (Category IV – severe risk)
The challenge in veterinary medicine is that many pets, just like people, can have elevated readings because they are anxious at the vet or they are just generally a little bit nervous and excited during examinations. Getting accurate readings requires proper technique with specialized equipment (most often using non-invasive Doppler ultrasound) – it is not nearly as easy as checking a person’s blood pressure where we just have to hold out our arms. Veterinary patients need to be calm, laying on their side so that the blood vessel is at the same level as the heart, they need to be comfortable with a cuff on their leg or tail, they need to be comfortable with the sound of the equipment and they need to hold still long enough so that we can get several different readings.
All these challenges make it difficult to know if the numbers we are getting at one time are ‘real’ or not. To ensure that we are not diagnosing hypertension incorrectly, veterinary specialists advise that we should have evidence to suggest that hypertension is present or that there is a predisposing disease, and then go look at the blood pressures readings to see if the values support our concern.
Hypertension is almost never an acute condition. It is an insidious chronic disease and may look like other diseases or normal aging. Here is a list of some symptoms that pets with hypertension may exhibit which you may notice at home:
- Weight Loss
- Anorexia or change in appetite
- Increased water intake or increased urination
- Dilated pupils that remain dilated, changes in the eye color, clarity, motion, or acute blindness
- Changes in mental status or behaviors; seizures, acting ‘old’
- Coughing not associated with other conditions, excessive panting
- Night yowling in older cats
As you can see, some of the symptoms could be associated with a variety of diseases so they are not diagnostic by themselves. Pets with underlying diseases that put them at higher risk for hypertension, benefit from regular and careful examinations by the veterinarian which may include checking their blood pressures. Pets age much more rapidly than people; for this reason we strongly recommend twice yearly examinations for our patients. The more we know what is ‘normal’ for your cat or dog, the more effectively we can interpret abnormal findings and initiate treatment.
At Hawthorne Hills Veterinary Hospital we prefer to collect blood pressure readings at the beginning of a visit or better yet, scheduling blood pressure evaluations as the only thing for that visit. If we can get the blood pressure done before looking in the ears, taking the temperature, trimming nails, giving vaccines, drawing blood or collecting urine – all things that can make our patients anxious or annoyed with us, we hope to minimize interference with a proper reading. For some patients, especially fractious cats and very anxious dogs, we may need to use sedative medications that do not affect the blood pressure to collect reliable readings. With time we find that many patients learn to relax when they know they won’t also be poked or prodded.
If you suspect your pet is experiencing any of these changes, don’t delay, make an appointment to have your pet examined and ask to have their blood pressure checked. Early treatment can reverse many of the changes and help your pet remain comfortable in their old age.
- Hypertension in Pets: http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=1216
- Hypertensive Retinopathy: http://www.eyecareforanimals.com/animal-eye-conditions/general/295-hypertensive-retinopathy.html
- Hyperthyroidism: http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=516
- Chronic renal failure: http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=516