Dental disease, weight issues and fleas were the most commonly diagnosed conditions for cats and dogs.
Dogs and cats most often suffer from diabetes, dental disease and much more.
Veterinarians believe a rise in canine diabetes, along with a surge in feline diabetes, are due to obesity.
The report also shows that cats aren't receiving proper medical care.
The largest pet health report ever compiled reveals a number of disturbing trends, such as a 46 percent increase in canine diabetes since 2005, and data showing that cat owners do not often seek veterinary care for their felines.
The State of Pet Health 2011 Report, recently released by Banfield Pet Hospital, comprises medical data from 2.1 million dogs and nearly 450,000 cats. The report analyzes pet health trends over the past five years, highlighting preventable and medically important diagnoses affecting cats and dogs.
It also outlines the most common diagnoses for U.S. dogs and cats in 2010. For dogs, the top five diagnoses in Banfield hospitals were dental tartar, otitis externa (an inflammation/infection of the ear), overweight, dermatitis, and fleas. For cats, the top five were dental tartar, fleas, overweight, tapeworms, and cystitis (bladder infections).
"In addition to the rising risk of preventable diseases, I am particularly concerned about the veterinary care that cats are not receiving," Jeffrey Klausner, senior vice president and chief medical officer at Banfield Pet Hospital, told Discovery News.
"In 2010, our hospitals treated nearly 1.7 million more dogs than cats," Klausner added. "Cats are just as susceptible to disease and parasites as dogs, but our numbers show that they are not getting the care they need and deserve."
Another puzzling trend is how pets in certain states appear to suffer more from particular diseases and conditions that have no apparent link to location.
For example, while there was an overall increase in feline and canine diabetes, the disease was more common in Iowa, Rhode Island, Idaho, Nevada and Delaware. Since diabetes cases also rose for people during this time, medical experts suspect that human obesity problems may be carrying over to pets.
Denise Elliott, a medical specialist in nutrition within Banfield's Medical Quality Advancement Team, informed Discovery News that, at least for felines, "the evidence clearly demonstrates that obesity from excess calories is the main driver of diabetes mellitus in cats."
"Therefore, the prevention of obesity and maintaining ideal healthy body condition is a fundamental component of keeping cats healthy," Elliott added.
The American College of Veterinary Internal Medicine is expected to announce preliminary findings concerning feline diabetes and obesity at a conference in June, with a full report scheduled for release later this year.
The most common disorder affecting both dogs and cats, however, is dental disease, affecting 78 percent of dogs and 68 percent of cats.
"Dental disease is associated with kidney and liver disease, so it is really important for pet owners to have their pet's mouth examined by a veterinarian and get regular cleanings," Klausner said.
Heartworm disease was also in the top three health risks for dogs, particularly in southern states. This potentially fatal disease was most often detected in dogs from Mississippi, Arkansas, Louisiana, Alabama, Texas and South Carolina.
Flea infestation was additionally among the top 10 diagnoses for dogs and cats.
"I think this might result partly from pet owners buying preventative medications at retail outlets and not talking with their veterinarian about which product is best for their pet, how to apply it, and how to avoid environmental contamination from fleas and flea eggs," Klausner explained.
A shift in dog breed preferences is another rising trend.
"There is a considerable increase in the popularity of smaller-breed dogs and a decrease in the popularity of larger-breed dogs," he said. "These findings are important because small- and large-breed dogs are prone to different diseases. This shift potentially affects a lot of people involved in veterinary medicine, from veterinary students to researchers."
In terms of preventing pet illnesses, veterinarians recommend twice-yearly check-ups, professional teeth cleanings at least once a year with regular at-home brushings in between, use of preventative flea and tick medications, and proper control of diet and exercise.