Looking back at previous columns, I realized that I have spent a much larger percentage of space on dogs than on cats. This hasn’t been intentional as I like cats (and currently own two of them myself and many others previously). It just seems that there is less information and research out there pertaining to cats. Maybe that’s just part of their mystique, but it also creates problems for veterinarians as there are some unique physiological differences between cats and other pets and there are fewer drugs available that are approved for use in cats. There is a saying in veterinary medicine that “cats are not small dogs” and this is very true. This week we will look at some fascinating things in the cat world.
Anatomically, there are some interesting quirks of cats. They only have 30 teeth (compared to 42 in dogs and 32 in people). But as anyone who has tried to pill a cat can attest, they know how to use those teeth very effectively! They also have a clavicle (collarbone) which dogs lack. Cats can also retract their claws voluntarily while dogs cannot. One of the biggest things about cats is that they can purr and they have managed to keep the exact way they do this a secret from scientists all these years. Basically, they can cause a very short vibration of the vocal chords and this happens both during inspiration and expiration, hence the sound is continuous.
Cats are obligate carnivores. This means they have evolved to eat meat and little else. Because of this, a cat’s liver lacks certain metabolic pathways that are unnecessary on a prey-based diet. This is the reason that many medications that are fine for humans and other animals can be toxic to cats. Aspirin and many other non-steroidal anti-inflammatories are a classic example of this. Cats also require certain amino acids in their diet that are not essential to other animals. Taurine is the most notable of these. A lack of taurine leads to dilative cardiomyopathy causing heart failure and retinal degeneration causing blindness. Because it is now required to add this to all commercial cat foods, the cases of these diseases has dramatically decreased. A cat’s liver also handles lack of eating differently. People and dogs can go for long periods of time without food without a long-term effect. Cats, however, will start to mobilize fat to their liver and this results in a disease called hepatic lipidosis. This is very serious and these cats need immediate nutrition, usually via a surgically implanted tube, often for weeks.
Some other diseases are specific to cats as well. Cats can become hyperthyroid (have an overactive thyroid) while dogs become hypothyroid (underactive thyroid). People can get either. Cats can get hypertrophic cardiomyopathy, which is a very thickened heart wall. This is very rare in dogs.
Cats have some unique behaviors. Unlike dogs, where a simple praise/correction technique is usually quite effective, cats will resent any form of punishment, particularly if it seen as coming from the owner. With litter box issues, especially, if the cat is punished for going outside the box, the problem will get worse and not better. Cats also do not tend towards being in structured social groups like dogs, although they certainly can live together in harmony. Many cats prefer to be “only children” and don’t necessarily need another cat around to be happy.
Many medications that are available for dogs are not labeled for cats. In many cases, they have been tested on cats but bringing a product to market is very expensive (to the tune of millions of dollars) and the drug companies often do the required studies on dogs only. So as veterinarians, we often have to go “extra-label”. If we didn’t, there would very little we could offer our feline patients. Rest assured, we do this with an intimate knowledge of the medications and how effective and safe they are for cats. We care about our kitty patients and strive to keep them healthy and happy.