ABOUT CATS

HISTORY AND DOMESTICATION

The modern-day housecat is a relatively new species that started to become domesticated about 10,000 years ago. The dog, in comparison, has been living in close association with humans almost three times longer, having become domesticated around 30,000 years ago.

Housecats (Felis catus) are believed to have evolved from the Middle Eastern Wildcat (Felis sylvestris). It is now commonly believed that the cat actually domesticated itself, finding a ready source of food (rodents) around the early agricultural settlements.

Early farmers, who began to store grain after harvests, likely saw the utility of having these astute hunters around to control the vermin population and, thus, a beautiful symbiotic relationship was born. The more friendly and tame felines were encouraged by farmers to hang around the settlements, and, through the process of natural selection, cats became more comfortable with humans, eventually finding their way into people’s homes and hearts.

Recent studies of the genetic composition of the modern-day housecat and its wildcat ancestor show that housecats have changed very little during the process of domestication. Perhaps this is so because humans used cats for their natural talent in rodent control and did not apply artificial selection pressure (or selective breeding) to change the genetics of the housecat. It was not until the 19th century that cat fanciers began selecting cats for particular traits, which has led to the 70 or so breeds of domestic cat that we have today.

BEHAVIOR

Given that their genes have changed little from their wildcat ancestors, it is no wonder the domestic cat has retained most of the behaviors and mannerisms of its close wild relatives. Today’s housecat has kept so much of its natural instincts and abilities that it can survive in the wild and hunt for its own food. Indeed, domestic cats signal and communicate with tail movements, postures, ear movements, etc., in almost identical ways to wildcats. Their ability to stalk, hunt, and take down prey also closely mimics their wildcat ancestors.

Like their wild counterparts, cats are primarily solitary hunters and are not pack animals. They are also both predators and prey. The cat’s close genetic link with its forbearers can explain its reaction to pain and injury as well. Just like wildcats, when injured or in pain, a domestic cat is not likely to vocalize and draw attention to itself, but instead seeks a place to hide and stay quiet to avoid attracting unwanted attention from predators.

COMMON FELINE MUSCULOSKELETAL (MS) DISORDERS

Musculoskeletal (MS) disorders are conditions that affect the bones, joints, tendons, ligaments, and muscles of the cat. Primary diseases of the bone in cats are rare. However, joint disorders are fairly common. The most common musculoskeletal disorder in cats is, by far, degenerative joint disease (DJD), also known as osteoarthritis or feline arthritis. One of the first studies into how common DJD is in cats was performed at NC State more than 15 years ago, and this study found that 90% of cats over 12 years of age had evidence of arthritis on x-rays (1). A more recent study by Lascelles and the team at NC State found that just over 90% of all cats have radiographic evidence of degenerative joint disease somewhere in the body (2). Other musculoskeletal disorders seen in cats include dysplasia of the hip, elbow, or shoulder; knee (patella) luxation; cruciate ligament disease; and tendon contracture.

DJD involves deterioration of all the components of the joint. This deterioration (of cartilage and the underlying supporting bone) results in inflammation and pain. In cats, the pain is most common in the hips, knees, hocks (ankles), lower back, and elbows. The condition is chronic and, with time, the pain may be so debilitating as to lead to a poor quality of life for the cat. Importantly, with time, pain that is not controlled can lead to changes in the pain-sensing system, resulting in a neuropathic type of pain in these cats.

DIAGNOSING MUSCULOSKELETAL DISEASE AND PAIN

Like their wild ancestors, domestic cats are very good at hiding their pain. This, coupled with their typical lack of cooperation during a physical and orthopedic exam, can make diagnosing the pain and finding its source very difficult, even for the most experienced veterinarians. X-rays (radiography) and MRIs are tools that can help diagnose a musculoskeletal condition; however, the source of the pain must first be localized. Therefore, a thorough history, including the owner’s assessment of changes in the cat’s behavior and activities, is essential for a diagnosis of musculoskeletal disorders and pain in the cat.

Changes in the cat’s daily habits that might indicate the cat is in pain include hiding, decreased grooming or excessive licking of a painful area, increased aggression when handled or agitation toward another pet, and avoidance of using the litter box (house-soiling). In addition, the cat’s mobility and activity level may be affected by the musculoskeletal condition and associated pain. Caregivers, therefore, may see a decrease in the cat’s willingness to jump up or down on obstacles, difficulty going up or down stairs, stiffness, less activity, an increase in time spent sleeping, and reluctance to play.

1. Hardje E M, Roe S C, Martin F R Radiographic evidence of degenerative joint disease in geriatric cats: 100 cases 1994-1997; J Am Vet Med Assoc 2002; 220; 628-32
2. Lascelles BDX, Thomson Sumrell A, Henry III JB, Brown J, Simpson W, Wheeler S, Hansen BD, Robertson I, Zamprogno H, Freire M, Pease A. Cross-sectional study evaluating the prevalence of radiographic degenerative joint disease in domesticated cats. Veterinary Surgery 2010;39: 535-44.