Aging Cats by Frank Utchen, DVM

In older cats, as in older people, a variety of health problems become more common than they are in younger cats and kittens. This week’s article will point out several things to watch for in your cat as they become older.  

First, how old is your cat, really? The system of assigning 7 cat years for each 1 year on our calendar is no longer considered accurate. The best way to calculate your cat’s age in human years is as follows: the first year of their life counts for 15 human years, then second year counts for 9 human years, and every year after that counts for 4 human years. So, for example, a 16 year old kitty is: 15 + 9 + (14 more years at 4 years each) = 80 in human years. The previous system would assign your kitty an age of 16 x 7 = 112. So your old girl or old boy is a lot younger than you thought!   

Nevertheless, as cats approach and pass the age of 10, various problems start popping up more frequently than in younger cats. Three of the most important are discussed below.  

Kidney Disease

Perhaps the most common medical problem faced by cats as they age is the onset of kidney failure. The kidneys make important hormones for the body, clean the blood, and determine how much water to keep in or filter out of the body. As a cat’s kidneys begin to fail—usually due to nothing other than age—they begin producing excess urine. The litter box for these cats will often be noticeably soaked. Cats typically do not drink much water; they will begin drinking more and more to keep up with the urinary water loss. Some cats begin to lose weight, eat less, and generally slow down. Of course, older cats often enjoy a relaxed pace of living anyway, so the slowing down may not be obvious. Simple blood and urine tests will help diagnose this condition. 

If an otherwise healthy-appearing cat is determined to be in the early stages of kidney failure, usually all that is recommended is a change in diet to a particular food designed for this condition, and the use of a medication called Calcitriol that helps protect the kidneys from further damage and helps cats feel better. As cats progress with this problem other medications may be helpful. Studies show that older cats diagnosed in kidney failure live an average of 277 days (about 9 months) when fed the proper food, yet live an average of 736 days (over 2 years) when given Calcitriol as well.

Hyperthyroidism

The thyroid gland is a small gland in the neck covered by the muscles adjacent to the larynx (“voice box”). This gland makes a hormone, tetraiodothyronine — otherwise just referred to as the “thyroid hormone” or as “T4”. In simple terms, this hormone sets the speed of one’s metabolism. The more hormone produced, the higher the metabolic rate. In cats whose thyroid gland becomes hyperactive, their metabolism speeds up. Those cats often have a high heart rate, dilated pupils, eat voraciously, and actually seem unusually hyper for an older cat. Most cats with this condition experience dramatic weight loss despite eating more because their metabolism is running so fast they burn up all the calories they eat, plus some.  

However, about 25% of hyperthyroid cats feel bad from the condition and become listless and inappetant. As with kidney failure, a simple blood test can determine if a cat is hyperthyroid. This condition can be treated either with oral medication given once or twice a day at home, or by receiving an injection of radioactive iodine which returns the thyroid gland to its normal rate of hormone production. In some instances surgery on the thyroid gland is appropriate.  

Cancer

Sadly, cancer is as common in our companion animals as it is in humans. Cancer can strike any organ or body part, and when it occurs internally there are often no indications while in the early stages. A general decline in vitality may be all that is noticed, including a drop in appetite and activity level. Sometimes it is necessary to take X-rays, perform an ultrasound exam, perform endoscopy or laparoscopy (look inside with small fiberoptic scopes) or do blood tests to determine if cancer is present.

Some cancerous conditions can be effectively managed with minimal medications (e.g., bladder tumors or lymphoma—a kind of cancer of the lymph nodes and blood cells), although other types of cancer require surgery or may not be treatable in any case. The decision to treat or not treat a cat with cancer can be a difficult one, and no single answer is right for all cats and all families.   

At our practice we recommend any cat over 10 years old have a physical exam yearly, regardless of whether they are due for any immunizations and even if they never leave the house. Often, a general screening set of blood and urine tests is done to determine what a particular cat’s baseline levels are for the various tests so there is a reference point for future test results that may become abnormal.

The Feline Leukemia Virus (FeLV) and the Feline Immunodeficiency Virus (FIV) By Frank Utchen, DVM

Two of the most devastating viral diseases for cats are Feline Leukemia and Feline AIDS. Each is caused by a virus for which there is no cure once a cat contracts it. Both viruses are in the family of viruses called Retroviruses, which puts them in the same group as the Human Immunodeficiency Virus. Fortunately, repeated studies of veterinarians who routinely come in contact with these diseases, and repeated unsuccessful attempts to grow these viruses in human cell cultures has confirmed that neither virus is transmissible to humans. 

  

For cats, these viruses are both spread by bite wounds, as the virus is secreted from a cat’s body into their saliva. As opposed to HIV, the Feline Immunodeficiency Virus is not a sexually transmitted disease. Therefore, even spayed and neutered cats can contract feline AIDS without the precondition of having mated with another cat.  

These viral diseases have the same biological behavior in cats as HIV does in humans. Initially, there is no indication that a cat has become infected. Any cat with a bite wound from another cat may have been exposed to either virus. In the case of the Leukemia virus, some cats will mount an immune response and fight off the virus immediately after exposure. However, the majority will not do so and will remain carriers of this deadly pathogen. Cats that are exposed to the Feline Immunodeficiency Virus always become carriers for life.  

Most studies indicate that approximately 40% of cats exposed to FeLV will fight off the virus, but the remaining 60% will remain infected and die within 3 years. A small percentage will live longer. With FIV, the average time to the onset of disease after a cat contracts the virus is much longer—approximately 10 years.  With either virus the primary problem that develops is the same: the immune system begins to fail, with consequences for a cat similar to those for people whose HIV infection has progressed to the clinical disease of AIDS. Eventually, almost all cats with either virus succumb to secondary bacterial infections and other diseases. In some cases, cats with the Leukemia Virus will in fact develop the cancer of leukemia (hence the moniker).  

Research into possible treatments for these diseases has largely been unsuccessful. There are reports that indicate the use of Interferon as an oral medication given daily can help maintain a cat’s immune function and thereby delay the onset of secondary infections. This has not been documented by controlled studies.  

The use of anti-viral drugs such as AZT used to treat AIDS has been documented to be helpful, but is expensive and impractical for routine use in cats. At present, it is considered that there is no cure for either of these diseases.  

There is an effective immunization against the Feline Leukemia Virus, although none exists for FIV. (An immunization against FIV has been developed and marketed by one pharmaceutical company, although the American Veterinary Medical Association, the American Association of Feline Practitioners and most veterinarians and veterinary immunologists recommend against its use due to lack of data indicating efficacy).

Once it is known that a cat is a carrier of either virus, that cat should be kept indoors thereafter to prevent it from interacting with other cats outdoors. This eliminates the risk of transmitting the virus(es) to unknown cats outdoors, and helps reduce the risk of secondary infections to the known carrier.   If a cat is confirmed as a carrier of the Feline Leukemia Virus and is to be kept indoors, all other cats in the house should be immunized against that virus. 

If a cat is confirmed as a carrier of FIV, there are no protective medical steps than can be taken to reduce the risk of transmission to other cats in the household, apart from isolating the cats from each other. Although FIV can only be transmitted through a bite wound contaminated by saliva, it has been postulated that there is about a 5% chance each year that a cat will contract FIV from another cat even without a bite wound. Whether this is because there are unknown incidents of biting, or transmission occurs through other contact with a carrier cat’s saliva, is not known.  

Veterinarians generally recommend all new kittens and cats have a blood test done to determine their status for these infections. Only cats that go outdoors are at risk for contracting these infections, so at our practice we do not recommend that indoor cats be immunized against the Leukemia Virus. If a cat is to go outdoors also, it should be immunized against the Leukemia Virus by receiving a series of two injections about three weeks apart, followed by a booster shot a year later, and then a booster every 3  years after that. Again, there are not preventive measures that can be taken to avoid FIV infection if a cat goes outdoors and encounters other cats. By testing your kitten for these infections we can begin to control the spread of these deadly viruses, and guarantee your kitten and other cats you may already have, all have as healthy a life as possible.

Dr. Utchen graduated from the University of Illinois College of Veterinary Medicine in 1986. In 1989 he and Dr. DeLano co-founded Norris Canyon Veterinary Medical Center in San Ramon, which in the year 2000 became Bishop Ranch Veterinary Center. His special interests are Orthopedic and Soft Tissue Surgery, Internal Medicine, Emergency/Critical Care, Dentistry, and Anesthesiology/Pain Management. He lives in San Ramon with his wife and 2 daughters and their two Cavalier King Charles Spaniels, Tori and Gus. 

Snail Bait Awareness by Frank Utchen, DVM

There are two main types of snail baits, and one is considered relatively safe for dogs. Look for the active ingredient and use the kind that contains 1% iron phosphate. This is relatively safe for dogs, because there is actually very little iron in the compound, and what there is, is poorly digested and absorbed by dogs, so most of it passes through them without incident. That being said, iron phosphate can still be toxic to dogs if they ingest enough of it: a 40 lb dog would have to consume about 3 lbs of this bait to receive a lethal dose of iron, although vomiting and diarrhea can occur with as little as about 1/10 of that amount.

Certain brands of snail bait contain an active ingredient called metaldehyde. Metaldehyde causes muscle tremors that progress to convulsions. Dogs can easily die from this poison. Each spring when the snails come out, we see numerous dogs at our practice that have ingested metaldehyde that require emergency treatment, including iv fluids, injections of anti-seizure medication, and a one or two-day hospital stay. Keep all potential poisons well out of reach of dogs. Pet-safe alternatives to snail baits with metaldehyde include Sluggo Slug and Snail Bait, handpicking, and copper barriers.