There is some very good information here about the real cost of having a dog that should be consdiered before adding another dog:
Of course, purchasing a dog is just the beginning of the demands on your wallet.
"The cost of the dog is the least expensive part of owning a dog," said Stephanie Shain, director of outreach for companion animals for the Humane Society of the United States. "What you'll spend every year in caring for the dog will exceed that."
The American Pet Products Manufacturers Association estimates the average yearly cost for a dog to be more than $1,200. Some typical expenses are veterinary care, grooming, dog training, rental housing pet deposits, supplies, toys, food, treats, pet sitting and licensing.
The most expensive years of a dog's life typically are the first year and the senior years.
For a puppy, first-year veterinary care will cover an entire vaccination series, spaying or neutering, heartworm preventive, flea and tick control and deworming.
"Dogs should see a veterinarian at least once a year," said Clark Fobian, president of the Missouri Veterinary Medical Association. "During about one-third of our routine examinations, we'll discover fleas, tapeworms, ear mites and other things the owners didn't realize the pets had."
The senior years bring health concerns related to aging. Medication to treat chronic conditions such as arthritis, diabetes or congestive heart disease can quickly add up to hundreds of dollars a year.
And contrary to what some pet owners think, getting a pure-bred dog in no way ensures a healthier dog, Fobian said. The "hybrid vigor" of mutts often makes mixed breeds a more affordable choice initially and in the long run.
Some breeds are more susceptible to certain conditions or ailments; others have inherent genetic diseases that owners must treat and factor into their pet-care budget.
"Some of these conditions can be chronic and lifelong," said Merry Crimi, companion-animal veterinarian in Portland, Ore., and past president of the American Animal Hospital Association.
Cockers and Shar-peis, for example, often have skin and ear infections that must be treated with antibiotics, shampoos and antifungal drugs throughout their lives. German Shepherd dogs can develop hip, back or pelvic problems later in life, Crimi said. Surgery on both hips can cost $4,000.
I think many people end up mistakenly thinking that when they've gotten through the expense of the first year with spaying or neutering, shots, etc., they are "home free" so to speak and can safely get another dog. As this article points out, the senior years (which are from around 6 and up) can be very expensive, especially with the number of genetic ailments Maltese are prone too. You may be able to afford 2 Maltese now, but will you be able to down the road?