Vet360 Vet360 Vol 05 Issue 03 - Page 18

FELINE MEDICINE High blood pressure Amlodipine is the most effective drug for high blood pressure in cats. But don’t use it unless there’s direct evidence of target organ damage, says Dr. St. Denis. Clinicians should also be certain the cat is hypertensive, following recommendations from the International Society of Feline Medicine (ISFM) guidelines for managing hypertension. She starts with 0.625 mg every 24 hours and reassesses in three to five days, and if blood pressure is higher than 160 mm Hg, she increases the dosage by 0.5 mg/kg/day. She maxes out amlodipine dosages at 2.5 mg/cat. Monitor blood pressure every three to four months. If amlodipine is not controlling blood pressure, first check adherence with the client. If everything checks out and you’ve maxed out your amlodipine dosage, Dr. St. Denis recommends adding in telmisartan (Semintra), a new angiotensin receptor blocker from Boehringer Ingelheim. Anecdotally, Dr. St. Denis finds it is a nice adjunct to amlodipine administration in uncontrolled hypertensive cases. What to do about phosphorus and calcium concentrations Therapeutic kidney diets are the first line of defense against abnormal calcium and phosphorus concentrations. If you find that phosphorus is still vet360 Issue 03 | JULY 2018 | 18 increasing or unacceptably high even if a cat is on a therapeutic diet, then a phosphate binder, such as aluminum hydroxide, is in order, Dr. St. Denis says. She advises avoiding any aluminum hydroxide products that contain calcium, splitting the daily dose, and giving with food because phosphate binders bind to phosphate in food. Renal secondary hyperparathyroidism is due to deficiency of calcitriol, which causes calcium dysregulation and increased ionized blood calcium in the bloodstream. If you notice hypercalcemia, it’s important to measure parathyroid hormone (PTH) and ionized calcium concentrations. If the PTH is normal or low, then hypercalcaemia is not due to renal secondary hyperparathyroidism. If you elect to prescribe calcitriol to manage calcium concentrations, Dr. St. Denis says to give twice weekly, ensure that phosphorus concentrations are less than 6 mg/dl in the blood, and monitor regularly. Check ionized calcium and PTH concentrations every four to six weeks until they normalize, then check them every three to six months, depending on what your client is willing to do. Reference available online