How to Determine a Kitten’s Age
The younger a cat, the easier it is for vets to determine about when she was born. “Factors such as the cat’s size and teeth can be very useful in pinpointing an age,” says Dr. Stephen Horvath, clinical assistant professor at the College of Veterinary Medicine at Ohio State University.
First, size. “Up until cats are about 4 to 6 months old, a good rule of thumb is that they gain a pound for every month,” Horvath explains. “So a 3-pound kitten is 3-months old, a 4-pound kitten is 4 months, and so on until about 6 months of age.”
Nappier concurs, adding that this method isn’t foolproof. “If the cat is in poor health, weight is no longer a reliable age indicator.”
Then there are the cat’s teeth. A kitten’s deciduous (baby) teeth start to come in when she’s about 2 weeks old, and finish when she’s about 8 weeks old. Then, at around 4 months old, the baby teeth start to fall out and adult teeth start to erupt. A cat should have all of her adult teeth by the time she’s 6 months old. “Once that happens, it’s really hard to tell how old a cat is by its teeth,” Horvath says.