Emerging diseases and solutions: Innovations in feline practice



Gary D. Norsworthy, DVM, DABVP
I have been a veterinarian for 31 years. Although progress in feline medicine was steady during the first 10 years of my career, the last decade has been like a snowball rolling down a hill. Technological advances have revolutionized much of what we do. Digital imaging systems—including radiography, ultrasonography, and magnetic resonance imaging—are used in private practices or, at the minimum, are readily obtainable. Laser surgery units make some of the most difficult surgical procedures relatively easy. However, there are less spectacular advances that merit attention. In this article, I'll discuss some of the innovations that I've found most useful in my feline practice.

Diagnosing diarrhea Diarrhea is one of the most common and frustrating conditions that I see. It's challenging because it can have so many causes. Many of the causal diseases, such as giardiasis, are not easily iagnosed. Practitioners consider giardiasis common based on how often drugs are used to treat the disease, but giardiasis cannot be confirmed easily. Several test modalities are available, but it's often necessary to repeat those tests several times before a positive result occurs in an infected cat. Recently, an in-house test was introduced that detects Giardia-soluble antigen (SNAP Giardia—IDEXX). This antigen is found consistently in the stool of infected dogs and cats. Tests that detect antigens are much more sensitive than fecal examination tests for Giardia cysts, which are found only sporadically. The SNAP Giardia test is also specific for Giardia. I routinely use the Giardia antigen test on cats with diarrhea. It can also be used as part of a routine screening profile for outdoor cats. The zoonotic implications of this disease make its detection even more important.


Figure 1. An Endo-Sof subcutaneous catheter implanted in a patient. (Photos Dr. Gary Norsworthy)
Diagnosing and treating renal diseases Chronic renal disease is one of the most common causes of death in senior cats. Although renal failure may be detected easily, it's not easy to treat; treatment is often unsuccessful when the clinical signs include anorexia, dehydration, and lethargy, and when the serum creatinine concentration is greater than 7.0 mg/dl. Renal insufficiency is the stage of chronic renal disease that precedes failure, often by many months.1 Cats with renal insufficiency have mildly elevated creatinine values, but may be asymptomatic or have very mild signs (mild polyuria and polydipsia, decreased appetite, and gradual weight loss). These cats have lost more than 75% of their renal function, but they can remain relatively healthy as long as appropriate measures are taken.As the disease progresses to renal failure, it's accompanied by marked polyuria and polydipsia, anorexia, marked weight loss, dehydration, and lethargy.

Screening senior cats for evidence of renal insufficiency is a rewarding undertaking. Common laboratory tests, such as creatinine and BUN concentrations and urine specific gravity, can help diagnose the condition. Treatment includes a renal disease diet, potassium supplementation, and benazepril administration. Renal diets contain reduced protein and phosphorus levels and are nonacidifying. Potassium gluconate supplementation (2 to 4 mEq/day) can improve renal function in many cats because cellular potassium depletion results in decreased appetite, body weight, and activity level. It can also decrease the glomerular filtration rate (GFR).2


Figure 2. Systemic blood pressure can be determined with Doppler or oscillometric units using a peripheral vein.
The ACE inhibitor benazepril has been shown to slow the progression of renal disease and extend the lives of these patients.3 The dosage is 2.5 mg/cat once a day for cats weighing up to 5 kg. Cats weighing 5 kg or more are given 5 mg/cat once a day. I begin treatment with this drug as soon as renal insufficiency is diagnosed.