Points to Ponder as our Feline Friends get Older

Dr. Kari Mundschenk

Board Member, American Association of Feline Practitioners

It should come as no surprise to any of us that as our feline friends get older, their bodies go through a series of changes.  We have all seen the changes--decreased body mass in a cat which used to be so muscular, lack of jumping onto the fence, increased vocalization at night.  With aging comes a responsibility of the owner and the veterinarian to realize what is happening and make adequate adjustments to dietary needs, protocols and the environment in which the cat lives.

Kitties age disproportionately as compared to humans.  The old standby of 1 cat year is equivalent to 7 human years just doesn't work.  Kitties are born as infants and are teenagers by the age of 6 months.  By the time they are 7 years of age, they are over 40 in human years.  Just as in humans, the medical needs of kitties needs to be adjusted to the stage of life they are currently going through.  Unlike humans, kitties are commonly living to be 18-20+ years of age (>100), and this is due to their owners catching on to the changes which are occurring and working closely with a veterinarian to maintain and monitor changes.

Much of the information presented tonight will be a precursor to the coming months with each topic building on the prior discussion.  If you have not received a copy of the first talk in the entire series, I encourage you to pick one up because it will be very important to have on hand for the next few months.

As kitties age, there are categories of diseases which your veterinarian will be more inclined to determine as the most likely cause of a problem.  Of course, some kitties "don't read the book" and any disease can be seen at any age.  The following table details some of the more common findings based on a retrospective study:

Top Diagnoses in Cats by Age Category

Modified from Lund EM, Armstrong PJ, Kirk CA; Health status and population characteristics examined at private veterinary practices in the United States, JAVMA 214: 1336, 1999

As you can see, there are similarities in all ages, but in certain locales and living conditions, certain diseases may be more prevalent, i.e. heartworm disease, giardia, neoplasia (cancer).

Now we will go over each organ system and discuss the more common changes with the aging process.  REMEMBER, AGE IS NOT A DISEASE.  It is important to be aware of the changes in order to make proper adjustments to diet, anesthesia, litter boses, and home environment.

Cardiovascular:  as kitties age, there is a change in cardiac function due to decreased ventricular compliance and cardiac reserve.  These changes render the heart and vessels to be stiffer than a younger kitty.  Common changes include the development of hypertension (high blood pressure) and an increased sensitivity to both dehydration and over hydration.  Additionally, kitties are experts at hiding heart disease so any increase in oxygen demand could make the kitty more susceptible to myocardial hypoxia.  At the hospital, decreasing fear, providing supplemental and/or pre-anesthetic oxygen, keeping the kitty warm, and using/not using medications which affect oxygen levels to the heart are ways we address the needs of your kitty.

Respiratory (pulmonary) system:  as with the heart, the respiratory system becomes stiffer which increases dead space in the airways and decreases the respiratory reserve for the kitty to draw upon when needed.  These changes are addressed by providing oxygen to potentially stressed kitties (with a loose fitting mask) and addressing critical illnesses as they increase the body's demand for oxygen.

Liver Function:  the kitty liver loses mass as the kitty ages.  The liver is the site of many important functions: important to energy, blood clotting, decontamination and protein function.  Maintaining proper body condition and addressing potential "toxins" goes a long way to assisting the liver with its day to day functions.

Renal (kidney):  as kitties age, renal blood flow decreases as does glomerular filtration rate and the number of functional glomeruli.  Changes in blood tests will not be detected until there is a loss of 2/3 of functioning nephrons.  Additionally, muscle mass plays a huge role in the cat as to the production of creatinine and blood urea nitrogen.  In the hospital, we need to recognize that most kitties over the age of 10-12 have some form of renal disease.  Additionally, maintaining proper fluid balance at home and in the hospital goes a long way in decreasing the effects of toxins, insulta, ischemia and medications on the kidneys.  Also, monitoring blood pressure will assist with providing proper care prior to severe damage to the system.

Central Nervous System:  the brain changes in kitties as in humans as a result of neuronal loss, cerebral blood flow declines and the quantity of neurotransmitters is reduced.  Additionally, some kitties deposit an amyloid-beta and amyloid precursor protein in the brain which can lead to cognitive dysfunction.

Endocrine Changes:  the most common endocrine changes in the kitty are hyperthyroidism and diabetes mellitus with kitties over the age of 7 years most commonly affected.  Recent research is also looking at a general decrease in adrenal function.

Musculoskeletal:  osteoarthritis is radiographically present in >75% of cats over the age of 12 years.  Adjustments and discomfort control need to be made to encourage continued movement and make life comfortable.  Loss of muscle mass is also common and is a primary reason diets may need to be adjusted as the kitty ages.  Muscle mass is important for kidney and liver function.

Gastrointestinal:  obesity due to a lack of exercise is common in kitties.  On the flip side, many kitties suffer from inappetance and decreased gastrointestinal function commonly associated with other diseases.  It is very important for a kitty to consume regular, small meals per day in order to maintain happy cells in the intestinal tract.

Oral Disease:  the mouth is the gateway to the body.  Any inflammation in the mouth has a direct effect on the heart, liver, kidneys and joints.

Special Senses:  as kitties age, the sense of smell (needed for appetite), hearing and vision decrease warranting adjustments to the daily care.

Fortunately, there are now more pet cats than dogs in North America.  Improved nutrition, prevention of infectious disease and advances in veterinary medical care has resulted in pets living longer and healthier lives.  In North America, over the last ten years, there has been a 15% increase in the cats over 10 years of age and the proportions of the feline population aged fifteen years or older has increased from 5% to 14%.  It's a great time to be a cat!!!

How can you help your kitty as he/she ages?

• Schedule regular examinations.  It is recommended that a minimum of 1 full exam/year be done in kitties under the age of 7 years.  At 7 years and above, a minimum 2 exams/year with  more frequent monitoring in kitties with clinical disease should be performed.
  
  
• Monitor organ function:  For kitties under the age of 7 years, it is recommended that a junior wellness profile +/- viruses be run yearly.  For kitties over the age of 7 years, a full panel which includes thyroid levels, urinalysis +/- viruses is run at least yearly and follow-up testing be determined based on findings.
  
  
• Have routine fecal analysis performed.  If on year-round parasite control, yearly testing should be performed.  If not on year-round control, then monitoring fecal samples every 3 months should be included in the routine.
  
  
• Monitor blood pressure status.  We generally start blood pressure readings around the age of 6-7 but certain situations, we may start earlier.  We monitor blood pressure under anesthesia and in all cases of thyroid and renal disease.
  
  
• Monitor nutritional needs and adjust as necessary.  In some situations, a specific appointment for nutritional consultation may be needed.
  
  
• Monitor oral disease and address problems as soon as possible.  Monitoring includes oral radiographs a minimum of 1 time per year.
  
  
• Address the stressors your kitty may be experiencing.  These include peer pressure, non-routine schedules, cold/heat, other pets, stray animals outside.  Dr. Buffington at Ohio State University has shown a direct correlation between disease and stress (in both directions).
  
  
• Address behavioral changes quickly as they may indicate signs of systemic disease.
  
  
• Provide lots of love and attention.  You, the owner, are the first person who will notice the changes your kitty may have.  (Please refer to talk titled "Ten Subtle Signs of Illness Every Cat Owner Should Know".)

Please join us next month for the next in our series of lectures.  The focus will be the start of our nutritional education.