DISEASES HUMANS AND ANIMALS SHARE
You’d be amazed by the number of diseases humans and animals share. the list is surprisingly long. In alphabetical order, it begins with Allergies. Anemia. Arthritis. Asthma. And atherosclerosis. Botulism, bronchitis, cataracts, deafness, DIABETES, epilepsy, and glaucoma.
HEART DISEASE, hemophilia, hepatitis, hypertension, infertility, and influenza. Plus leukemia, lung disease, lupus, Lyme disease, malaria, and measles. Narcolepsy, nerve damage, polio, rabies, rubella, scoliosis, and skin diseases. Smallpox, tetanus, tuberculosis, ulcers, and Yellow fever.
And of course the big C. Did you know that CANCER is the most common cause of death in dogs? Today, doctors and veterinarians are working together – sharing research results and other information to find a cure for both species.
You can learn more about the diseases humans and animals share at the One Health Initiative.
DIABETES IN PEOPLE + COMPANION ANIMALS
- Diabetes mellitus refers to a group of serious metabolic disorders common in humans, dogs, and cats, in which the patient sustains a high level of blood sugar over a prolonged period because the pancreas either doesn’t produce enough insulin, or the cells of the body do not respond properly to the insulin. If untreated, in people it often leads to complications including diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS), which are potentially life-threatening, as well as cardiovascular disease, stroke, chronic kidney disease, foot ulcers, and eye damage. Common complications of diabetes in dogs include hypoglycemia, or low blood sugar that may result from incorrect insulin dosing, ketoacidosis, and cataracts. Feline patients may also suffer from hypoglycemia and ketoacidosis, in addition to pancreatitis, recurrent infection, and nerve dysfunction that affects posture and balance.
- The International Diabetes Federation estimates 415 million people were living with diabetes in 2015, or roughly 8.3% of the adult population, while the World Health Organization estimates the disease was responsible for 1.5 to five million deaths between 2012 and 2015. Veterinary researchers believe diabetes is underdiagnosed in cats and dogs, but estimate .5 to 2 percent of the feline population and .34 percent of canines suffer from the condition. The 60-day survival rate of dogs who are diagnosed with diabetes is only 50 percent.
Researchers have used animal models to study diabetes for nearly 100 years, leading to breakthroughs that have saved and improved the lives of people and animals living with the condition.
- The peptide hormone insulin, which causes diabetes either by its absence or by the failure of other cells to properly respond to it, was first discovered in research with dogs conducted in the late 19th and early 20th centuries. Its extraction from the animals’ pancreas and formulation into an injectable proved immediately effective in treating diabetes symptoms at a time when hospitals were packed with wards of children rendered comatose by diabetic ketoacidosis, which, at that time, was invariably fatal. Insulin injections are now the most common way of treating and managing type 1 diabetes mellitus in humans and pets. The version of the hormone procured from pigs was the most common variant used in dogs, cats, and people until human insulin could be produced in large quantities by recombinant DNA technologies.
- The most widely-prescribed anti-diabetic medication in the world, Metformin hydrochloride, is included in the World Health Organization’s List of Essential Medicines for its efficacy in lowering blood sugar, “bad” cholesterol, and triglyceride levels in type 2 diabetics with minimal adverse side effects. The drug has also been used effectively in the treatment of dogs with diabetes, especially those with obesity problems or resistance to insulin. It was developed in part by studies with rabbits, which demonstrated its success in lowering blood sugar.
- There is no cure for diabetes, and while it can be managed in many cases with insulin and medications like Metformin, research has identified some specific lifestyle changes that can improve and extend the lives of people and pets living with the condition. Studies with animal models—primarily mice, rats, and desert gerbils, but also cats, non-human primates, dogs, and pigs—have led to tremendous developments in the scientific and medical understanding of which diets and how much/what kind of exercise are most effective for patients with diabetes.
HEART DISEASE IN PEOPLE + COMPANION ANIMALS
- Cardiovascular disease (CVD) is an umbrella term for diseases involving the heart or blood vessels. They affect human patients, as well as cats and dogs, and in people include coronary artery diseases like angina and myocardial infarction (heart attack), as well as stroke, heart failure, cardiomyopathy, heart arrhythmia, aortic aneurysms, congenital heart disease, and others. Cats suffer most often from cardiomyopathy, a disease of the heart muscle in which the organ walls are either too thick, too thin, too stiff, or any combination of the three conditions. By contrast, the types of CVD experienced by canines usually vary by the dog’s size and breed; diseases of the heart valves (“leaky” valvular disease) prevent normal heart function most often in small dogs, while larger dogs will experience myocardial disease like dilated cardiomyopathy, where the heart’s main pumping chamber is enlarged, in some cases preventing the organ from relaxing and filling with blood as it should.
- Together, heart disease in humans represents the leading cause of death in the world. It’s nearly as common in canines, affecting an estimated 7.8 million dogs in the United States. Though cats are less often diagnosed with CVD, cardiomyopathy can portend a poor prognosis in felines, especially when detected early in the cat’s life. Meanwhile, only 50 percent of dogs diagnosed with symptoms of congestive heart failure due to mitral valve insufficiency will survive longer than six-12 months.
Animal research has led to breakthroughs in the treatment of CVD in people and companion animals, leading to a decrease in mortality rates and a multipronged approach to reducing patient risk.
- The discovery of cholesterol compounds, and the resulting medical knowledge about their role in CVDs including heart attack, stroke, peripheral vascular disease, atherosclerosis, and coronary artery disease, provided the first clues about how to reduce patient risk. The link was first reported in the early 20th century by a Russian scientist who fed purified cholesterol to rabbits and found it had caused vascular damage. Building on this early work, researchers determined the pattern of cholesterol carriers, lipoproteins, was key to gauging CVD risk. Clinical trials conducted in the 1970s and 1980s revealed another culprit—a genetic basis that prevented some people from successfully removing a pro-heart disease form of cholesterol, LDL, from their blood. So, with the knowledge that high levels of cholesterol in the bloodstream are a causative factor for heart disease (the “lipid hypothesis”), and provided that scientists understand some people are, genetically speaking, more vulnerable to CVDs than others, what can be done to reduce their risk?
- “In both man and animals, the most obvious factor that affects the blood lipids is diet.” Research on mitigating CVD risk and lowering blood cholesterol levels has hinged on both studies with animal models and human clinical trials. This work has produced dietary recommendations for patients with risk factors associated with heart disease, and for people, generally. While acquired heart disease in pets is not preventable, and cannot be reversed, research points to low-sodium diets as a means of slowing its progression—by reducing fluid build-up from the enlarged heart.
- Blood pressure medication, statins, niacin, fibrates, CETP Inhibitors, ACE Inhibitors, diuretics, vasodilators, and positive inotropes…the first five pharmaceutical interventions are prescribed to reduce CVD risk, prevent the disease’s progression, reduce the risk of death, and lower blood cholesterol levels in people. The latter four can reduce fluid buildup, decrease pressure on the heart, treat hypertension (high blood pressure), and improve congestive heart failure outcomes in cats and dogs. Each medication, indispensable in the effort to reduce CVD fatalities in people and their pets, was developed and tested by research with animal models.
CANCER IN PEOPLE + COMPANION ANIMALS
- Cancer refers to a group of more than 100 diseases characterized by abnormal cellular growth. They can produce malignant tumors that promote blood vessel constriction and invade tissues—thereby interfering with the biological functions necessary to live. In people, dogs, and cats, many factors can increase the risk of developing cancer, but it’s most common in older patients. The most common forms of cancer in people are: breast cancer, prostate cancer, lung/bronchial cancer, colorectal cancer, uterine cancer, bladder cancer, skin cancer, thyroid cancer, kidney/renal cancer, and non-Hodgkin’s lymphoma (cancer that starts in white blood cells called lymphocytes). Canines often suffer from lymphoma (tumor of the lymph nodes), breast cancer, osteosarcomas (bone cancer), and soft tissue sarcomas (which can develop in fat, muscle, blood vessels, and deep skin tissues). Their feline counterparts are less prone to osteosarcomas, but are susceptible to other cancers that commonly affect dogs, in addition to abdominal tumors and skin cancer. The disease’s progression in humans and animals follows a similar path, which has enabled researchers to develop nearly identical treatment options for two and four-legged patients.
- Even despite significant medical advances in early diagnosis and treatment, cancer remains the second leading cause of death (behind cardiovascular disease, or CVD) in people around the world. The Centers for Disease Control and Prevention (CDC) reports nearly 600,000 fatalities from cancer in the United States last year. In companion animals, it’s deadly, too: the disease accounts for approximately 32 percent of deaths in cats older than 10. And in dogs, cancer is as common as it is in men. It’s the number one killer of man’s best friend.
Thanks to animal research, a menu of treatment options is available to patients based on the type, grade, and location of their—or their pets’—disease. And many will survive.
- The development in the 1970s of computed topography (CAT scans—first used to capture images of porcine tissue), magnetic resonance imaging (MRI scans), and positron emission topography (PET scans) facilitated the surgical removal of cancerous tumors. The gradual development of less invasive surgeries over the years was made possible by animal models, and now, both human and animal cancer patients benefit from the procedures.
- Chemotherapy, arguably the most well-known, and one of the most common treatments for many times of cancer in humans and pets, was developed by research with animals. Promising results of mouse studies, in which an engineered compound of nitrogen mustard demonstrated success in halting the animals’ lymphomas, paved the way for modern cancer chemotherapy. The toxicity of the compounds, recommended dose, and the identifiable stages of cancer progression in which this therapy is most successful were all determinations made through research with animal models.
- In radiation therapy, ionized radiation is applied to tumors, causing cellular death in cancerous tissue. It’s often a curative therapy, but it can also be used in conjunction with chemotherapy in the treatment of most cancer types in human, canine, and feline patients. Radiation therapy first demonstrated its potential for use in cancer treatment by studies with animals.
- A major focus of the scientific and medical research communities in recent years has been the promise of a relatively-new treatment called immunotherapy. It works by using the patient’s immune system to target and attack cancer cells. The first successful study, in 1984, showed that by blocking a protein receptor called CTLA-4, T cells in the immune systems of mice could destroy cancerous tumors. The treatment has been adapted for use in both human and animal patients—and may represent a new frontier of cancer research, potentially curbing the lethality of this devastating disease.
LYME DISEASE IN PEOPLE + COMPANION ANIMALS
- Lyme disease, which can affect people, dogs, and—less commonly—cats, belongs to a category of diseases called vector-borne illnesses. They are so characterized by their path of transmission from host animals that live in the wild to the vector, in this case, the back-legged “deer tick,” to humans or pets. If people infected with Lyme disease are not treated, resulting symptoms can include loss of the ability to move one or both sides of the face, joint pains, severe headaches, and heart palpitations. With treatment, about 10 to 20 percent of patients experience joint pains, memory problems, and fatigue for at least six months. Meanwhile, clinical symptoms in dogs often include loss of appetite, generalized pain, the appearance that they’re “walking on eggshells,” and painful lameness (limping).
- The Centers for Disease Control and Prevention (CDC) reports a steady increase in reported Lyme disease cases in the United States since the mid-1990s, with nearly 300,000 confirmed cases in 2015. It’s difficult to ascertain the number of dogs who are infected, but it’s more common in canines than in people—and its incidence in the former can be used as part of a surveillance system to track and monitor Lyme disease risk for all affected populations.
Virtually all that’s known about Lyme disease, including how best to treat it, is known through research with animals—which has also shown promise in unlocking ecological solutions that could successfully curb the rate of infection.
- Because Lyme disease infection in humans and dogs mirrors the progression of infection in mice, the antibiotic treatment regimen used for human and canine patients was first tested in mouse models. And antibiotics, which are used to treat and prevent a variety of bacterial infections in people and animals, were first developed in studies with mice, rabbits, and other laboratory animals.
- Because Lyme disease can be difficult to diagnose, researchers have proposed ecological interventions that could potentially interfere with the bacteria’s life cycle. One of these methods would involve the creation of strains of mice that would be born immune to Lyme. If enough are released into the wild, they would mate with wild white-footed mice—the disease’s natural host—and eventually, the entire population could become resistant. This proposed solution, which would involve changes to the ecosystem, is far from ready for implementation and would require additional studies with laboratory animals to ensure it’s safe and effective.
- A second ecological approach would mimic the interventions used to reduce the incidence of diseases like rabies: the vaccination of wild animals. By inoculating the host, the thought is, researchers could curb the rate of infection among populations of people and companion animals who encounter either the host or the vector. Animal research has played a crucial role in the development of this approach, research that has strengthened the likelihood of a USDA approval to deploy the vaccine in the field (to populations of white-footed mice).